JP4159719B2

JP4159719B2 - Method of manufacturing contact material for power vacuum circuit breaker

Info

Publication number: JP4159719B2
Application number: JP2000047979A
Authority: JP
Inventors: 功奥富; 貴史草野; 敦史山本
Original assignee: Toshiba Corp
Current assignee: Toshiba Corp
Priority date: 2000-02-24
Filing date: 2000-02-24
Publication date: 2008-10-01
Anticipated expiration: 2020-02-24
Also published as: JP2001236864A

Description

【０００１】
【発明の属する技術分野】
この発明は、すぐれた遮断特性と再点弧抑制特性とを備えた真空バルブ等からなる電力用真空遮断器の接点材料の製造方法に関する。
【０００２】
【従来の技術】
真空中でのアーク拡散性を利用して、高真空中で電流遮断を行わせる真空バルブの接点は、対向する固定、可動の２つの接点から構成されている。
【０００３】
真空遮断器には、大電流断性能、耐電圧性能、耐溶着性能の基本的３要件の他に再点弧現象の発生の抑制が重要な要件となっている。
【０００４】
しかしながら、これらの要件の中には相反するものがある関係上、単一の金属種によって総ての要件を満足させることは不可能である。この為実用されている多くの接点材料に於いては、不足する性能を相互に補るような２種以上の元素を組合せることによって、例えば大電流用、高耐圧用などのように特定の用途に合った接点材料の選択採用が行われ、それなりに優れた特性を持つ真空バルブが開発されているが、さらに強まる要求を充分満足する真空バルブは未だ得られていないのが実情である。
【０００５】
例えば、大電流遮断性を目的とした接点として、Ｃｒを５０ｗｔ％程度含有させたＣｕ−Ｃｒ合金（特公昭４５−３５１０１号）が知られている。この合金は、Ｃｒ自体がＣｕと略同等の蒸気圧特性を保持しかつ強力なガスのゲッタ作用を示す等の効果で高電圧大電流断性を実現し、高耐圧特性と大容量遮断とを両立させ得る接点として多用されている。
【０００６】
この合金は、活性度の高いＣｒを使用していることから、原料粉の選択、不純物の混入、雰囲気の管理などに十分に配慮しながら接点素材を製造（焼結工程など）したり、接点素材から接点片へと加工に配慮しながら接点製品としている。
【０００７】
しかし再点弧の発生が引金となって遮断性能を低下させる場合が見られ、その改善が望まれている。
【０００８】
【発明が解決しようとする課題】
ＣｕＣｒ接点は、両者の高温度での蒸気圧特性が近似していることなどが主因となって、電流遮断後でも接点表面は比較的平滑な損傷特性を示し、安定した電気特性（安定した接触抵抗特性、優れた遮断特性、再点弧抑制など）を発揮している。しかし近年では一層の大電流遮断やより高電圧が印加される可能性のある回路への適応が日常的に行われる結果、接点として加工した新品時の表面状態、電流遮断後の接点表面の損傷状態などによっては、再点弧の誘発が見られるようになってきた。すなわち加工時の表面状態や、電流遮断によって異常的に損傷・消耗した接点表面では、次の定常電流の開閉時の接触抵抗の異常上昇や温度の異常上昇を引起こす原因となったり、耐電圧不良を示し、再点弧発生の一因となっている。
【０００９】
研究によれば、ＣｕＣｒ合金の再点弧特性と遮断特性は、合金中のＣｒ量の変動、Ｃｒ粒子の粒度分布、Ｃｒ粒子の偏析の程度、合金中に存在する空孔の程度などに依存することが判明した。また、ＣｕＣｒ合金の再点弧特性と遮断特性は、合金中のＣｕ相の特に遮断前と遮断後との表面状態の変化状況にも依存することが判明した。
【００１０】
しかしその最適化を進めているにも拘らず、上述した近年の適応状況では、まだばらつきが見られ、両特性を兼備した真空バルブが必要となって来た。
【００１１】
この発明は、このような点に鑑み為されたもので、その目的は、ＣｕＣｒ合金の再点弧特性を安定化させ電流遮断特性の優れた電力用真空遮断器の接点材料の製造方法を提供することにある。
【００１２】
【課題を解決するための手段】
上記発明の目的を達成する為に、請求項１に記載の本発明は、Ｃｕ又はＣｕを主成分とするＣｕ合金で構成されるＣｕ相より成る導電性成分と、Ｃｒより成る耐弧性成分とで構成された１０〜９０重量％Ｃｕを含有するＣｕ−Ｃｒ合金からなる電力用真空遮断器の接点材料の製造方法に於いて、先ず、前記Ｃｕ−Ｃｒ合金をＣｕ相の持つ融解温度の直下温度の１０３０℃〜１０８０℃に加熱し、これを常温にまで冷却したときの、前記Ｃｕ−Ｃｒ合金中のＣｒ粒子のマイクロビッカース硬さ値Ｈｒを求めておき、次いで、粒径が０．１〜１５０μｍのＣｒ粉と粒径が４４〜６２μｍのＣｕ粉とを所定比率で混合して所定値で加圧後、所定温度で焼結、若しくは所定量の前記Ｃｒ粉を所定値で加圧し、８００〜１４００℃で焼結後、１１００〜１４００℃でＣｕ塊を溶浸し、常温にまで所定速度で冷却したときの、前記Ｃｕ−Ｃｒ合金中のＣｒ粒子のマイクロビッカース硬さ値をＨｓとしたとき、［Ｈｓ／Ｈｒ］比が１．０〜１．６の範囲になるように、前記加圧時の圧力、前記焼結時の温度および前記冷却時の速度の１つ以上を調整したことを特徴とする電力用真空遮断器の接点材料の製造方法である。
【００１３】
ここで、上記接点材料製造時（焼結工程後若しくは焼結・溶浸工程後）のＣｒ粒子の硬度値Ｈｓは、原料Ｃｒの内容や焼結、溶浸時に選択した熱処理条件や接点材料加工時の残存歪みの程度などが互いに関連し合って決定され、例えばＨｓのビッカース硬さは２００近傍の値を示す。
【００１４】
ところで、この接点材料を真空バルブとして組み込み実際に稼働させると、定常電流開閉時や事故電流遮断時にアーク熱を受け、接点面は次第に変化（軟化）し最後には一定の硬度値Ｈ_Bを示す様になり、その間に最初のビッカース硬さ２００近傍の硬度値Ｈｓから大きく低下する。実際に真空バルブを稼働させた後最後に一定となった時の硬度値Ｈ_Bと、上記Ｃｕ相の融解温度の直下温度Ｔ１に加熱した後、常温にまで冷却した時のＣｒ粒子の硬度値Ｈｒとを対比すると、両者（Ｈ_B、Ｈｒ）はほぼ近似の硬度値を示していることが判った。
【００１５】
ところでＨ_Bの測定には真空バルブを製造すること、実際に電流の遮断や開閉の作業を要することなどで経済的、時間的負担が大きく不利の為、Ｈ_BとＨｒとがほぼ近似した値となる前記性質を利用して、ＨｒによってＨ_Bを代用すること、すなわち測定の困難なＨ_Bに代わって、測定の容易なＨｒによって、定常電流開閉時や事故電流遮断時の接点面の軟化の状況をおきかえることが可能であり有益である。
【００１６】
また上記接点材料製造時のＣｒ粒子の硬度値Ｈｓが大で、常温にまで冷却した時の硬度値Ｈｒとの差が大きい程（すなわち［Ｈｓ／Ｈｒ］比が大）、再点弧の発生頻度が大の傾向になることも判った。[Ｈｓ／Ｈｒ]比として１．６を越えた接点を選択すると、Ｃｕ−Ｃｒ合金中のＣｒ粒子とＣｕ相との硬度の差が大となり、接点の機械的仕上げ加工に際し硬さの差によって安定した加工表面状態が得られず、目標とする低再点弧化に対して好ましくない。
【００１８】
ここで、Ｃｕ相の持つ融解温度の直下温度Ｔ１より低い温度（ｌ０３０℃より低い温度）で熱処理した時のＣｒの硬さ値と、電流遮断・開閉経過後のＣｒの硬さ値Ｈ_Bとが一致しない。その為、Ｔ１より低い温度で熱処理した時のＣｒの硬さ値を使用すると、[Ｈｓ／Ｈｒ]比と再点弧発生頻度との間の関係は、十分には対応が取れず製品の管理が出来なくなる。
【００２６】
また、Ｃｕ−Ｃｒ合金中のＣｕ相の量が１０重量％未満では、電流遮断特性が大幅に低下する。Ｃｕ相の量が９０重量％を越えると、１．６以下の［Ｈｓ／Ｈｒ］比を確保することが困難となり、再点弧発生頻度が増大する。
【００３５】
また、請求項２に記載の本発明は、Ｃｕ又はＣｕを主成分とするＣｕ合金で構成されるＣｕ相より成る導電性成分と、Ｃｒより成る耐弧性成分とで構成された１０〜９０重量％Ｃｕを含有するＣｕ−Ｃｒ合金からなる電力用真空遮断器の接点材料の製造方法に於いて、先ず、前記Ｃｕ−Ｃｒ合金をＣｕ相の持つ融解温度の直下温度の１０３０℃〜１０８０℃に加熱し、これを常温にまで冷却したときの、前記Ｃｕ−Ｃｒ合金中のＣｕ相のマイクロビッカース硬さ値Ｈｏを求めておき、次いで、粒径が０．１〜１５０μｍのＣｒ粉と粒径が４４〜６２μｍのＣｕ粉とを所定比率で混合して所定値で加圧後、所定温度で焼結、若しくは所定量の前記Ｃｒ粉を所定値で加圧し、８００〜１４００℃で焼結後、１１００〜１４００℃でＣｕ塊を溶浸し、常温にまで所定速度で冷却したときの、前記Ｃｕ−Ｃｒ合金中のＣｕ相のマイクロビッカース硬さ値をＨｍとしたとき、［Ｈｍ／Ｈｏ］比が１．０〜２．０の範囲になるように、前記加圧時の圧力、前記焼結時の温度および前記冷却時の速度の１つ以上を調整したことを特徴とする電力用真空遮断器の接点材料の製造方法である。
【００３６】
ここで、上記接点材料製造時（焼結工程後若しくは焼結・溶浸工程後）のＣｕ相の硬度値Ｈｍは、焼結、溶浸時に選択した熱処理条件（例えば冷却速度など）や接点加工時の残存歪みの程度などが互いに関連し合って決定され、Ｈｍのビッカース硬さは１００近傍の値である。
【００３７】
ところで、この接点材料を真空バルブとして組み込み実際に稼働させると、定常電流の開閉時や事故電流の遮断時のアーク熱により、接点面は次第に変化（軟化）し、最後には一定の硬度値Ｈｂを示すようになり、その間に初期のビッカース硬さ１００近傍の硬度値Ｈｍから大きく変化（低下）する。実際に真空バルブを稼働させて最後に一定となった時の硬度値Ｈｂと、上記Ｃｕ相の融解温度の直下温度Ｔ１に加熱した後、常温にまで冷却した時のＣｕ相の硬度値Ｈｏとを対比すると、両者（Ｈｂ、Ｈｏ）は、ほぼ近似の硬度値を示していることが判った。
【００３８】
ところでＨｂの測定には，真空バルブを製造しなければならないこと、実際の電流の遮断や開閉作業をしなければならないことなどで経済的、時間的負担が大きく不利の為、ＨｂとＨｏとがほぼ近似した値となる前記性質を利用して、ＨｏによってＨｂを代用すること、すなわち測定の困難なＨｂに代わって、測定の容易なＨｏによって、定常電流開閉時や事故電流遮断時の接点面の軟化の状況をおきかえることが可能であり有益である。
【００３９】
また上記接点材料の焼結・溶浸後のＣｕ相の硬度値Ｈｍが大で、常温にまで冷却した時のＣｕ相の硬度値Ｈｏとの差（すなわちＨｍ／Ｈｏ］比）が大きい程、再点弧の発生頻度が大の傾向になることも判った。[Ｈｍ／Ｈｏ］比として２．０を越えた接点を選択すると、Ｃｕ−Ｃｒ合金中のＣｕ相とＣｒ粒子との硬度の差が大となり、接点の機械的仕上げ加工に際し硬さの差によって安定した加工表面状態が得られず、目標とする低再点弧化に対して好ましくない。
【００４１】
ここで、Ｃｕ相の持つ融解温度の直下温度Ｔ１より低い温度（１０３０℃より低い温度）で熱処理した時のＣｕ相の硬さ値と、電流遮断・開閉経過後のＣｕ相の硬さ値Ｈｂとが一致しない。その為、Ｔ１より低い温度で熱処理した時のＣｕ相の硬さ値を使用すると、[Ｈｍ／Ｈｏ]比と再点弧発生頻度との間の関係は、十分には対応が取れず製品の品質管理が出来なくなる。
【００４９】
また、Ｃｕ−Ｃｒ合金中のＣｕ相の量が１０重量％未満では、電流遮断特性が大幅に低下する。Ｃｕ相の量が９０重量％を越えると、接点表面の消耗が大となり再点弧発生頻度が増大する。
【００５８】
【発明の実施の形態】
以下、本発明の実施形態について詳細に説明する。
【００５９】
Ｃｕ−Ｃｒ接点の材料状態と再点弧発生について、発明者らの観察では、遮断前後の材料特性と、再点弧のバラツキ発生との間の関連性について、以下の様な知見を得た。
▲１▼Ｃｕ−Ｃｒ接点は、研磨、研削や切削手段によって仕上げ加工するのが一般である。しかしＣｕ−Ｃｒの諸内容（製造条件や加工条件など）を一定としても、なお再点弧の発生にバラツキが見られる。発明者らの観察の結果、接点表面にはＣｒ粒子の脱落、Ｃｕ相部分の脱落、流れ（ＣｕがＣｒ粒子上にまでかぶる）や剥離、Ｃｒ粒子端部の欠け、引っかき状の傷など種々存在していた。その一因として接点面上の特にミクロ領域での加工性の差異、すなわち再点弧発生のバラツキとミクロ領域での硬度の均一度の違いとの間に相関性を認めた。この傾向は、接点素材の製造ロット間で、および１枚の接点のミクロ領域中でも観察された。
▲２▼更に、定常電流開閉動作や事故電流遮断動作の経過によって、次第に再点弧発生頻度は、ほぼ一定値に安定してゆく場合が認められた。この状況はアーク熱を受け接点面が次第に変化（軟化）し最後には一定の硬度値となる現象を示していると考えられる。
【００６０】
そこで、実際の真空バルブに対して、事故電流遮断動作を多数回与えてほぼ一定値となった接点のＣｒ粒子の硬度値Ｈ_B、及びＣｕ相の硬度値Ｈｂを測定した。その接点のＣｕ相部分の融解温度の直下温度を選択し、その温度で十分加熱した後、常温にまで冷却した時の、同接点中のＣｒ粒子の硬度値Ｈｒ及びＣｕ相の硬度値Ｈｏとそれぞれ対比すると、両者は、それぞれ、ほぼ近似の値（Ｈ_B＝Ｈｒ、Ｈｂ＝Ｈｏ）を示していることが判った。
▲３▼更に、Ｃｒ粒子の硬度値については、焼結工程後若しくは焼結・溶浸工程後の、Ｃｕ−Ｃｒ合金中のＣｒ粒子の硬度値（マイクロビッカース硬さ値）をＨｓとして、Ｃｕ−Ｃｒ合金中のＣｕ相の融解温度の直下温度に加熱し、これを常温にまで冷却した時の、Ｃｕ−Ｃｒ合金中のＣｒ粒子の硬度値（マイクロビッカース硬さ値）をＨｒとした時、Ｈｓが大で、Ｈｒとの差が大きい程（すなわち［Ｈｓ／Ｈｒ］比が大の程）、再点弧の発生頻度が大の傾向にあることを認めた。［Ｈｓ／Ｈｒ］比として１．６を越えた接点を選択すると、Ｃｕ−Ｃｒ合金中のＣｒ粒子とＣｕ相との硬度の差が大となり、接点の機械的仕上げ加工の際に好ましい加工表面状態が得られず、目標とする低再点弧化に対して好ましくない。これに対して、［Ｈｓ／Ｈｒ］比として１．６以下好ましくは１．３以下の接点を選択すると、Ｃｒ粒子とＣｕ相との硬度の差が小となり、接点の機械的仕上げ加工に際し、好ましい加工表面状態が得られ、常に一定の安定した表面状態を得て、アークの停滞、集中が低減化される結果、接点面の局部的異常蒸発現象の阻止や表面荒れの軽減化などによって、低再点弧化の利益と共に遮断特性の向上に寄与する。
【００６１】
また、Ｃｕ相の硬度値についても、焼結工程後若しくは焼結・溶浸工程直後の、Ｃｕ−Ｃｒ合金中のＣｕ相の硬度値（マイクロビッカース硬さ値）をＨｍとして、Ｃｕ−Ｃｒ合金中のＣｕ相の融解温度の直下温度に加熱し、これを常温にまで冷却した時の、Ｃｕ−Ｃｒ合金中のＣｕ相の硬度値（マイクロビッカース硬さ値）をＨｏとした時、Ｈｍが大で、Ｈｏとの差が大きい程（すなわち［Ｈｍ／Ｈｏ］比が大の程）、再点弧の発生頻度が大の傾向にあることを認めた。［Ｈｍ／Ｈｏ］比として２．０を越えた接点を選択すると、Ｃｒ粒子とＣｕ相との硬度の差が大となり、接点の機械的仕上げ加工の際に好ましい加工表面状態が得られず、目標とする低再点弧化に対して好ましくない。これに対して、[Ｈｍ／Ｈｏ]比として２．０以下好ましくは１．３以下の接点を選択すると、Ｃｒ粒子とＣｕ相との硬度の差が小となり、接点の機械的仕上げ加工に際し、好ましい加工表面状態が得られ、常に一定の安定した表面状態を得て、アークの停滞、集中が低減化される結果、接点面のＣｕ相部分の局部的な異常蒸発現象を阻止、表面荒れの軽減化などによって、低再点弧化の利益と共に遮断特性の向上に寄与する。
▲４▼このような接点に外部磁界（例えば縦磁界）を与えると、遮断により発生したアークは、接点面上に一様に拡がり移動拡散し、電流遮断特性を向上させることが出来る。観察によれば、一定値以上の電流値を遮断すると、アークは予測出来ない一点もしくは複数点の場所で停滞する傾向を示すが、〔Ｈｓ／Ｈｒ］比が１．６以下の接点の方が、１．６を越えた接点よりもその程度は低く優れている傾向にあり、また［Ｈｍ／Ｈｏ］比が２．０以下の接点の方が、２．０を越えた接点よりもその程度は低く優れている傾向にある。最終的には接点の一部分を異常融解させ遮断限界に至る。また異常融解によって瞬時的爆発的な蒸発によって発生した金属蒸気は、開極過程にあった真空遮断器の絶縁回復性を著しく阻害し、遮断限界の一層の劣化を招く。さらに異常融解は、巨大な融滴を作り接点面の荒れを招き耐電圧特性の低下、再点弧発生率の増加、材料の異常な消耗をも招く。これらの現象の一因となるアークが、接点面上のどこで停滞するかは全く予測出来ない以上、発生したアークが停滞させることなく移動拡散できるような表面条件と移動拡散を促進させる手段とを接点に与えることが望ましい。本発明では、その望ましい条件として、Ｃｕ−Ｃｒ合金中のＣｒ粒子に関する［Ｈｓ／Ｈｒ］比、またはＣｕ−Ｃｒ合金中のＣｕ相に関する［Ｈｍ／Ｈｏ］比が重要となる。
【００６２】
［１］［Ｈｓ／Ｈｒ］比を調整する実施例
上述のように、ＣｕＣｒ合金の接点特性の安定化には、合金中のＣｒ量の変動、Ｃｒ粒子の粒度、粒度分布、Ｃｒの偏析の程度、合金中に存在する空孔の程度などに依存することを認めたが、特に再点弧特性のより一層の安定化には、上記に加えてＣｕＣｒ合金中のＣｒ粒子の挙動が極めて重要であることが判った。すなわち真空バルブの再点弧の発生頻度は、遮断前後の合金中のＣｒの硬度の変化について注目する必要があることが判った。
【００６３】
そこで、まずＣｕ−Ｃｒ合金中のＣｒ粒子に関する［Ｈｓ／Ｈｒ］比を調整して接点材料を製造する実施例及び比較例について説明する。なお、実施例及び比較例の試作の条件を図１及び図２に、またこれらの実施例及び比較例の評価結果を図３及び図４に示す。
【００６４】
（遮断特性の評価）
表面粗さを５μｍに仕上げたフラット接点と、同じ表面粗さを持つ曲率半径１００Ｒの凸状接点とを対向させ、両接点を、開閉機構を持つ真空度１０^-3Ｐａ．以下に排気した着脱可能な真空遮断実験装置に取り付け、荷重４０ｋｇ、７．２ｋＶ−２０ｋＡ〜３１．５ｋＡで投入・遮断を１０回操り返し、溶着や再点弧の発生が軽微の時を「合格」とし、投入・遮断を１０回繰り返し、溶着や再点弧の発生多発の時を「不合格」とした。
【００６５】
（再点弧特性の評価）
６ｋＶ×５００Ａの回路を１０００回遮断させた時の再点弧発生頻度を６台の真空バルブについて測定した。発生率（×１０^-3（％））が０．３以下を評価Ｓ、０．３〜１の範囲を評価Ａ、１〜３の範囲を評価Ｂ、３〜１０の範囲を評価Ｃ、１０〜１００の範囲を評価Ｙ、１００以上を評価Ｚとした。
【００６６】
（硬さの測定）
Ｃｕ相部分、Ｃｒ粒子を個別にマイクロビッカース硬度計を用いて荷重１０〜２５ｇｒ．にて測定した。
【００６７】
（［Ｈｓ／Ｈｒ］比の調整）
接点は固相焼結法、固相・溶浸法のいずれでも製造は可能であるが、ここではＣｒスケルトンを製造し、その空隙にＣｕを溶浸させる方法で製造した例について示す。粒子直径が４４〜６２μｍの範囲にあるＣｕ粉（全Ｃｕ粉中に９５〜９９％占める）を用意した。粒子直径が０．１〜１５０μｍの範囲にあるＣｒ粉（全Ｃｒ粉中に９５〜９９％占める）の中から、これと近似した粒子直径を持つＣｕを用意した。
【００６８】
焼結工程後若しくは焼結・溶浸工程後の、前記Ｃｕ−Ｃｒ合金中のＣｒ粒子の硬度値（マイクロビッカース硬さ値）をＨｓ、該Ｃｕ−Ｃｒ合金中のＣｕ相の持つ融解温度の直下温度に加熱し、これを常温にまで冷却した時の、Ｃｕ−Ｃｒ合金中のＣｒ粒子の硬度値（マイクロビッカース硬さ値）をＨｒとした時の［Ｈｓ／Ｈｒ］比は、次のようにして調整した。
▲１▼Ｃｒ粉を成形する時にＣｒ粉に与える加圧力を、０〜８トン／ｃｍ²（Ｃｒを容器にいれそのまま焼結した時を加圧力０とする）の範囲で調整する。例えば同比率を大とする時には、高加圧力値を選択する。
▲２▼Ｃｒスケルトンを製造する時の焼結温度を、８００〜１４００℃の範囲で調整する。例えば同比率を大とする時には、この温度範囲の中から低めの温度を選択する。
▲３▼Ｃｒスケルトン中にＣｕを溶浸する時の温度を、１１００〜１４００℃の範囲で調整する。例えば同比率を大とする時には、溶浸温度は低目を選択する。
▲４▼溶浸後の常温にまで冷却する時の冷却速度を、０．１〜１０℃／分の範囲に調整する。例えば同比率を大とする時には、小さい冷却速度を選択する。
▲５▼焼結、焼結・溶浸後の接点に対して、再加熱処理を追加し、その温度を、５００〜１０７０℃の範囲で調整する。例えば同比率を大とする時には、例えば低めの６５０〜７５０℃での再加熱処理温度を選択する。
▲６▼焼結、焼結・溶浸後の接点に対して、再加圧処理を追加し、再加圧力を４〜１０トン／ｃｍ²の範囲で調整する。例えば同比率を大とする時には、再加圧処理前の相対密度が大となるよう、高めの再加圧力を選択する。
▲７▼［Ｈｓ／Ｈｒ］比を更に微調整する際には、Ｃｕ相に対してはＣｒ，Ｔｉ，Ｖ，Ｂ，Ｎｂ，Ｔａより選ばれた１つを適宜量添加する。
▲８▼Ｃｒ粒子に対してＴｉ，Ｖ，Ｎｂ，Ｔａより選ばれた１つ、または第１の補助成分としてのＡｌ，Ｓｉの少なくとも一方を適宜量添加することによって、前記比率の微調整は可能である。
【００６９】
これら▲１▼▲２▼▲３▼▲４▼▲５▼▲６▼▲７▼▲８▼などを適宜組合わせることによって［Ｈｓ／Ｈｒ］比を調整した接点を得た。
【００７０】
（実施例１〜３、比較例１〜２）
上述のように用意したＣｕ粉とＣｒ粉とを用いて、固相・溶浸法によって所定の［Ｈｓ／Ｈｒ］比を有する７５％Ｃｕ−残部Ｃｒ合金を製造した（実施例１〜３、比較例１〜２）。［Ｈｓ／Ｈｒ］比を調整する為に、接点製造に際しては上記▲１▼〜▲８▼の適宜選択又は組み合わせによって、１．０〜１．６（実施例１〜３）、１．９〜２．３（比較例１〜２）の［Ｈｓ／Ｈｒ］比を有する接点を選出した。
【００７１】
これらの接点を評価用真空パルプに搭載し、前記所定条件で再点弧発生頻度（×１０^-3％で示した数値）と遮断特性とを測定した。［Ｈｓ／Ｈｒ］比＝１．０の場合では、６台のバルブを評価したところ、再点弧発生頻度は、評価（Ｓ〜Ａ）を示し良好な特性を発揮した。遮断特性は、３１．５ｋＡの１０回遮断に成功し遮断特性も「合格」である。評価前の接点加工表面の観察によれば、Ｃｒ粒子部分、Ｃｕ相部分の区別なくほぼ均一に切削研磨された状況が見られ、極めて安定した接点表面状態を示し、Ｃｒ粒子の脱落、研磨傷などによる表面荒れは見られていない。評価後の接点の最表面層の顕微鏡的観察でも、最表面層領域からのＣｒ粒子の脱落もなかった（実施例１）。
【００７２】
また、［Ｈｓ／Ｈｒ］比＝１．３の場合では、再点弧発生頻度は、評価（Ａ〜Ｂ）を示し良好な特性を発揮した。遮断特性は、２４ｋＡの１０回遮断に成功し遮断特性も「合格」である。Ｃｒ粒子部分、Ｃｕ相部分の区別なくほぼ均一に切削研磨された状況が見られ、極めて安定した接点表面の加工状態を示し、Ｃｒ粒子の脱落、研磨傷などによる表面荒れは見られていない（実施例２）。
【００７３】
更に、［Ｈｓ／Ｈｒ］比＝１．６の場合でも、再点弧発生頻度は、評価（Ｃ）を示し良好な特性を発揮した。遮断特性は、２０ｋＡの１０回遮断に成功し遮断特性も「合格」である。Ｃｒ粒子部分、Ｃｕ相部分の区別なくほぼ均一に切削研磨された状況が見られ、Ｃｒ粒子の脱落、研磨傷などによる表面荒れはなく、極めて安定した接点表面状態を示している（実施例３）。
【００７４】
これに対して、［Ｈｓ／Ｈｒ］比＝１．９の場合では、再点弧発生頻度は、評価（Ｃ〜Ｙ）を示し再点弧特性に大幅な劣化が見られると共に大きなバラツキも示し好ましくない。遮断特性も、２０ｋＡの遮断テストに於いて多数の遮断不能を示し「不合格」である。遮断前の加工表面にはＣｒ粒子の脱落跡が観察されている。遮断後の接点面には局所的な荒れが存在している（比較例１）。
【００７５】
また、［Ｈｓ／Ｈｒ］比＝２．３の場合では、再点弧発生頻度は、評価（Ｚ）を示し再点弧特性に大幅な劣化が見られる。遮断特性も、２０ｋＡの遮断テストに於いて多数の遮断不能を示し「不合格」である。加工面の静耐圧値に大きなバラツキが見られている（比較例２）。
【００７６】
以上から、再点弧特性と遮断特性との両立に対して、［Ｈｓ／Ｈｒ］比の管理が極めて重要であると共に、同比率を１．０〜１．６の範囲を選択する時に目的を達する。
【００７７】
（実施例４〜６、比較例３〜４）
前記実施例では、Ｃｕ−Ｃｒ合金中のＣｕの量を７５％に一定とした時の、［Ｈｓ／Ｈｒ］比を変動させた場合の再点弧特性と遮断特性に及ぼす効果を示したが、本発明技術はＣｕ量７５％に限ることなく、Ｃｕの量が９０〜１０％（実施例４〜６）に於いても効果を発揮する。
【００７８】
すなわち、［Ｈｓ／Ｈｒ］比＝１．４に一定とした時、Ｃｕ量が９０％の場合では、再点弧発生頻度は、評価（Ｃ）を示し良好な特性を発揮した。遮断特性も、２０ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例４）。
【００７９】
Ｃｕ量が５０％の場合でも、再点弧発生頻度は、評価（Ｂ〜Ｃ）を示し良好な特性を発揮した。遮断特性も、２４ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例５）。
【００８０】
Ｃｕ量が１０％の場合でも、再点弧発生頻度は、評価（Ａ〜Ｂ）を示し良好な特性を発揮した。遮断特性も、２０ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例６）。
【００８１】
これに対して、Ｃｕ量が９５％の場合では、再点弧発生頻度は、評価（Ｃ〜Ｙ）を示し、再点弧特性に大福な劣化が見られると共に大きなバラツキも示し好ましくない。但し遮断特性は、２０ｋＡの遮断に成功し遮断特性では「合格」であったが、総合的には目的達成に対して好ましくない（比較例３）。
【００８２】
一方、Ｃｕ量が５％の場合では、再点弧発生頻度は、評価（Ｙ〜Ｚ）を示し再点弧特性に大福な劣化が見られる共に大きなバラツキも示し好ましくない。遮断特性も、２０ｋＡの遮断テストに於いて多数の遮断不能を示し「不合格」である。遮断特性が著しく低下していると共に遮断テスト中の温度上昇特性、遮断テスト後の接触抵抗特性共に低下が顕著に示された（比較例４）。
【００８３】
（実施例７〜１２）
前記実施例１〜６では、Ｃｕ−Ｃｒ合金中のＣｕ相中には、０．０１％のＣｒ成分を含有したＣｕを使用した例についてその効果を示したが、本発明技術はＣｕ相中の成分は、０．０１％のＣｒに限ることなく効果を発揮する。
【００８４】
すなわち、Ｃｕ−Ｃｒ合金中のＣｕの量を７５％に一定とした時、Ｃｕ相中に、０．２％のＣｒ成分を含有した７５％Ｃｕ接点では、再点弧発生頻度は、評価（Ｓ〜Ａ）を示し極めて良好な特性を発揮した。遮断特性も、３１．５ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例７）。
【００８５】
Ｃｕ相中に、０．５％のＴｉを含有させた接点では、再点弧発生頻度は、評価（Ｂ〜Ｃ）を示し良好な特性を発揮した。遮断特性も、２０ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例８）。
【００８６】
Ｃｕ相中に、１．０％のＶを含有させた接点では、再点弧発生頻度は、評価（Ｂ〜Ｃ）を示し良好な特性を発揮した。遮断特性も、２０ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例９）。
【００８７】
Ｃｕ相中に、１．０％のＢを含有させた接点では、再点弧発生頻度は、評価（Ｂ〜Ｃ）を示し良好な特性を発揮した。遮断特性も、２０ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例１０）。
【００８８】
Ｃｕ相中に、１０％のＮｂを含有させた接点では、再点弧発生頻度は、評価（Ｂ）を示し良好な特性を発揮した。遮断特性も、２４ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例１０）。
【００８９】
Ｃｕ相中に、２０％のＴａを含有させた接点では、再点弧発生頻度は、評価（Ｂ）を示し良好な特性を発揮した。遮断特性も、２４ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例１２）。
【００９０】
（実施例１３〜１６）
Ｃｕ−Ｃｒ合金中のＣｒ粒子中の成分として、Ｔｉ，Ｖ，Ｎｂ，Ｔａを含有したＣｒを使用した場合には、再点弧特性、遮断特性の安定化に有益である。
【００９１】
すなわち、Ｃｒ粒子中１．０％のＴｉを含有させた接点では、再点弧発生頻度は、評価（Ｓ〜Ａ）を示し極めて良好な特性を発揮した。遮断特性も、３１．５ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例１３）。
【００９２】
Ｃｒ粒子中２．０％のＶを含有させた接点では、再点弧発生頻度は、評価（Ｂ）を示し良好な特性を発揮した。遮断特性も、２４ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例１４）。
【００９３】
Ｃｒ粒子中２５％のＮｂを含有させた接点では、再点弧発生頻度は、評価（Ａ〜Ｂ）を示し良好な特性を発揮した。遮断特性も、２４ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例１５）。
【００９４】
Ｃｒ粒子中５０％のＴａを含有させた接点では、再点弧発生頻度は、評価（Ｂ）を示し良好な特性を発揮した。遮断特性も、２４ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例１６）。
【００９５】
（実施例１７〜１８、比較例５）
前記実施例１〜１６では、０．１〜１５０μｍの平均粒子直径を有するＣｒ粒子が全Ｃｒ粒子の９５％（容積％）以上を占める例についてその効果を示したが、本発明技術では全Ｃｒ粒子中に占める０．１〜１５０μｍの平均粒子直径を有するＣｒ粒子は９５％以上の場合に限ることなく効果を発揮する。
【００９６】
すなわち、全Ｃｒ粒子中に占める平均粒子直径０．１〜１５０μｍのＣｒの比率が８５％（容積％）のＣｒを使用した接点では、再点弧発生頻度は、評価（Ｂ）を示し良好な特性を発揮した。遮断特性も、２４ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例１７）。
【００９７】
全Ｃｒ粒子中に占める平均粒子直径０．１〜１５０μｍのＣｒの比率が７５％（容積％）のＣｒを使用した接点では、再点弧発生頻度は、評価（Ｂ〜Ｃ）を示し良好な特性を発揮した。遮断特性も、２０ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例１８）。
【００９８】
これに対して、全Ｃｒ粒子中に占める平均粒子直径０．１〜１５０μｍのＣｒの比率必５０％（容積％）のＣｒを使用した接点では、再点弧発生頻度は、評価（Ｂ〜Ｚ）を示し再点弧特性に大幅な劣化が見られると共に大きなバラツキも示し好ましくない。遮断特性も、２０ｋＡの遮断に成功と２０ｋＡの遮断に失敗とが存在しバラツキが大で遮断特性は「不合格」である（比較例５）。
【００９９】
（実施例１９〜２３、比較例６）
Ｃｕ−Ｃｒ合金中のＣｒ粒子中の第１の補助成分として、１．０％以下のＡｌ，Ｓｉを含有したＣｒを使用した場合には、再点弧特性、遮断特性の安定化に有益である。
【０１００】
すなわち、Ｃｒ粒子中に１．０％のＡｌを含有させた接点では、再点弧発生頻度は、評価（Ａ〜Ｂ）を示し良好な特性を発揮した。遮断特性も、２４ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例１９）。
【０１０１】
Ｃｒ粒子中に０．１％のＡｌを含有させた接点では、再点弧発生頻度は、評価（Ｓ〜Ａ）を示し良好な特性を発揮した。遮断特性も、３１．５ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例２０）。
【０１０２】
Ｃｒ粒子中に０．０１％のＡｌを含有させた接点では、再点弧発生頻度は、評価（Ｓ〜Ａ）を示し極めて良好な特性を発揮した。遮断特性も、３１．５ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例２１）。
【０１０３】
Ｃｒ粒子中に０．００１％のＡｌを含有させた接点では、再点弧発生頻度は、評価（Ｓ〜Ａ）を示し極めて良好な特性を発揮した。遮断特性も、３１．５ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例２２）。
【０１０４】
Ｃｒ粒子中に０．０１％のＳｉを含有させた接点では、再点弧発生頻度は、評価（Ｓ〜Ａ）を示し極めて良好な特性を発揮した。遮断特性も、３１．５ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例２３）。
【０１０５】
これに対して、Ｃｒ粒子中に１．５％のＡｌを含有させた接点では、再点弧発生頻度は、評価（Ｙ〜Ｚ）を示し好ましくない。遮断特性も、３１．５ｋＡの遮断テストに於いて１０回中８回再点弧発生したバルブがあり「不合格」である（比較例６）。
【０１０６】
（実施例２４〜２９、比較例７〜８）
第２の補助成分として、１．０％以下のＢｉ，Ｓｂを含有したＣｕ−Ｃｒ合金を使用した場合には、再点弧特性、遮断特性の安定化に有益である。また他の第２の補助成分として、５．０％以下のＴｅ，Ｓｅ，Ｐｂを含有したＣｕ−Ｃｒ合金を使用した場合にも、再点弧特性、遮断特性の安定化に有益である。
【０１０７】
すなわち、Ｃｕ−Ｃｒ合金中の第２の補助成分として、０．１％のＢｉを含有させた接点では、再点弧発生頻度は、評価（Ｂ）を示し良好な特性を発揮した。遮断特性も、２４ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例２４）。
【０１０８】
Ｃｕ−Ｃｒ合金中の第２の補助成分として１．０％のＢｉを含有させた接点では、再点弧発生頻度は、評価（Ｂ〜Ｃ）を示し良好な特性を発揮した。遮断特性も、２０ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例２５）。
【０１０９】
Ｃｕ−Ｃｒ合金中の第２の補助成分として、０．２％のＳｂを含有させた接点では、再点弧発生頻度は、評価（Ｂ〜Ｃ）を示し良好な特性を発揮した。遮断特性も、２０ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例２６）。
【０１１０】
Ｃｕ−Ｃｒ合金中の第２の補助成分として、２．５％のＴｅを含有させた接点では、再点弧発生頻度は、評価（Ｂ〜Ｃ）を示し良好な特性を発揮した。遮断特性も、２０ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例２７）。
【０１１１】
Ｃｕ−Ｃｒ合金中の第２の補助成分として、５．０％のＴｅを含有させた接点では、再点弧発生頻度は、評価（Ｃ）を示し良好な特性を発揮した。遮断特性も、２０ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例２８）。
【０１１２】
Ｃｕ−Ｃｒ合金中の第２の補助成分として、２．５％のＳｅを含有させた接点では、再点弧発生頻度は、評価（Ｂ〜Ｃ）を示し良好な特性を発揮した。遮断特性も、２０ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例２９）。
【０１１３】
また、第２の補助成分として、０．２％のＰｂを含有させた接点でも同等の再点弧発生頻度および遮断特性を発揮し「合格」である。
【０１１４】
Ｃｕ−Ｃｒ合金中の第２の補助成分として、３．０％のＢｉを含有させた接点では、再点弧発生頻度は、評価（Ｙ〜Ｚ）を示し再点弧特性に大幅な劣化が見られ好ましくない。遮断特性も、２０ｋＡ以下の遮断で再点弧が多発し遮断特性は「不合格」である（比較例７）。遮断テスト後の接点表面には著しい荒れが見られる。接触抵抗にもバラツキが見られた。
【０１１５】
Ｃｕ−Ｃｒ合金中の第２の補助成分として、８．０％のＴｅを含有させた接点では、再点弧発生頻度は、評価（Ｙ〜Ｚ）を示し再点弧特性に大福な劣化が見られると共に大きなバラツキも示し好ましくない。遮断特性も、２０ｋＡの遮断に成功と２０ｋＡの遮断に失敗とが存在しバラツキが大で遮断特性は「不合格」である（比較例８）。遮断テスト後の接点表面には著しい荒れが見られる。接触抵抗にもバラツキが見られた。
【０１１６】
（その他の実施例）
焼結工程後若しくは焼結・溶浸工程後のＣｕ−Ｃｒを、非酸化性雰囲気中で、Ｃｕ−Ｃｒ合金中のＣｕ相の融解温度以下の温度またはＣｕ相の融解温度以上の温度で加熱し、これを常温にまで冷却することとし、この場合も焼結工程後若しくは焼結・溶浸工程後の、Ｃｕ−Ｃｒ合金中のＣｒ粒子の硬度値（マイクロビッカース硬さ値）をＨｓ、非酸化性雰囲気中で、Ｃｕ−Ｃｒ合金中のＣｕ相の融解温度以下の温度またはＣｕ相の融解温度以上の温度で加熱し、これを常温にまで冷却した時の、Ｃｕ−Ｃｒ合金中のＣｒ粒子の硬度値（マイクロビッカース硬さ値）をＨｒとした時の［Ｈｓ／Ｈｒ］比を、１．０〜１．６の範囲に調整することとしてもよい。
【０１１７】
このように、Ｃｕ−Ｃｒ接点材料の製造雰囲気として、非酸化性雰囲気を選択することにより、特に再点弧発生頻度の低減化を図ることができる。
【０１１８】
［２］［Ｈｍ／Ｈｏ］比を調整する実施例
また、上述のように、ＣｕＣｒ合金の接点特性の安定化には、合金中のＣｕ相の状態（表面荒れ、空孔の程度）、Ｃｕ相の大きさ（粒度、粒度分布析の程度）などに依存することを認めたが、特に再点弧特性のより一層の安定化には、上記に加えてＣｕ−Ｃｒ合金中のＣｕ相の挙動が極めて重要であることが判った。すなわち真空バルブの再点弧の発生頻度は、遮断前後の合金中のＣｕの硬度の変化について注目する必要があることが判った。
【０１１９】
そこで、Ｃｕ−Ｃｒ合金中のＣｕ相に関する［Ｈｍ／Ｈｏ］比を調整して接点材料を製造する実施例及び比較例について説明する。なお、実施例及び比較例の試作の条件を図５及び図６に、またこれらの実施例及び比較例の評価結果を図７及び図８に示す。
【０１２０】
（遮断特性の評価）
この［Ｈｍ／Ｈｏ］比を調整する実施例の場合も、［Ｈｓ／Ｈｒ］比を調整する実施例の場合と同様に、表面粗さを５μmに仕上げたフラット接点と、同じ表面粗さを持つ曲率半径１００Ｒの凸状接点とを対向させ、両接点を開閉機構を持つ真空度１０^-3Ｐａ．以下に排気した着脱可能な真空遮断実験装置に取り付け、荷重４０ｋｇ、７．２ｋＶ−２０ｋＡ〜３１．５ｋＡで投入・遮断を１０回繰り返し、溶着や再点弧の発生が軽徴の時を「合格」とした。投入・遮断を１０回繰り返し、再点弧や溶着の発生多発の時を「不合格」とした。
【０１２１】
（再点弧特性の評価）
６ｋＶ×５００Ａの回路を１０００回遮断させた時の再点弧発生頻度を６台の真空バルブについて測定した。発生率（×１０^-3（％））が０．３以下を評価Ｓ、０．３から〜１の範囲を評価Ａ、１〜３の範囲を評価Ｂ、３〜１０の範囲を評価Ｃ、１０〜１００の範囲を評価Ｙ、１００以上を評価Ｚとした。
【０１２２】
（硬さの測定）
Ｃｕ相部分を、マイクロビッカース硬度計を用いて荷重１０〜２５ｇｒ．にて測定した。
【０１２３】
（［Ｈｍ／Ｈｏ］の調整）
接点は固相焼結法、焼結・溶浸法のいずれでも製造は可能である。焼結工程後若しくは焼結・溶浸工程後のＣｕ−Ｃｒ合金中のＣｕ相の硬度値（マイクロビッカース硬さ値）をＨｍ、Ｃｕ−Ｃｒ合金中のＣｕ相の持つ融解温度の直下温度に加熱し、これを常温にまで冷却した時の、Ｃｕ−Ｃｒ合金中のＣｕ相の硬度値（マイクロビッカース硬さ値）をＨｏとした時の所定の［Ｈｍ／Ｈｏ］比を持つ接点は、次のようにして調整した。
（１）前者の固相焼結法を採用した製造では、粒子直径が０．１〜１５０μｍの範囲にあるＣｒ粉（全Ｃｒ粉中に９５〜９９％占める）を用意し、これと近似した粒子直径を持つＣｕとして、４４〜６２μｍの範囲にあるＣｕ粉（全Ｃｕ粉中に９５〜９９％占める）を用意する。所定比率のＣｕとＣｒとを混合、成型した後、例えば１０３０℃で固相焼結してＣｕ−Ｃｒ合金を製造する。なおＣｕ−Ｃｒ合金中のＣｕ量が５〜９５％の総ての範囲の合金に対して採用可能であるが、主としてＣｕ量が６０〜９５％、５〜４５％の範囲の合金に対して適用した。
【０１２４】
Ａ）Ｃｕ−Ｃｒ混合粉を成形する時に混合粉に与える加圧力を、０〜８トン／ｃｍ²（Ｃｒを容器に入れそのまま焼結した時を加圧力０とする）の範囲で［Ｈｍ／Ｈｏ］比を小さく調整する。
【０１２５】
Ｂ）固相焼結後の常温にまで冷却する時の冷却速度を、０．１〜１０℃／分の範囲に調整する。例えば冷却速度をより小さく選択すると、Ｃｕ相の硬度値Ｈｍは小となり、［Ｈｍ／Ｈｏ］比率を小とするのに有益である。
【０１２６】
Ｃ）固相焼結後の接点に対して、再加圧力が４〜１０トン／ｃｍ²の範囲の再加圧処理を追加し、[Ｈｍ／Ｈｏ］比を小さく調整する。
【０１２７】
Ｄ）［Ｈｍ／Ｈｏ］比を更に微調整する際には、Ｃｕ相に対してはＣｒ，Ｔｉ，Ｖ，Ｂ，Ｎｂ，Ｔａより選ばれた１つを適宜量添加することによって、または第１の補助成分としてのＡｌ，Ｓｉの少なくとも一方を適宜量添加することによって、前記比率の微調整は可能である。これらＡ）Ｂ）Ｃ）Ｄ）などを適宜組合わせることによって［Ｈｍ／Ｈｏ］比を調整した接点を得た。
（２）後者の溶浸法を採用した製造では、粒子直径が０．１〜１５０μｍの範囲にあるＣｒ粉（全Ｃｒ粉中に９５〜９９％占める）を用意する。溶浸用のＣｕ塊を用意する。このＣｒを用いて例えば１２００℃でＣｒスケルトンを製造した後、その空隙にＣｕを溶浸させＣｕ−Ｃｒ合金を製造する。なおＣｕ−Ｃｒ合金中のＣｕ量が４５〜６０％の範囲の合金に対して適用した。
▲１▼Ｃｒ粉を成形する時にＣｒ粉に与える加圧力を、０〜８トン／ｃｍ²（Ｃｒを容器にいれそのまま焼結した時を加圧力０とする）の範囲で調整する。例えば同比率を大とする時には、高加圧力値を選択する。
▲２▼Ｃｒスケルトン中にＣｕを溶浸する時の温度を、１１００〜１４００℃の範囲で調整する。
▲３▼溶浸後の常温にまで冷却する時の冷却速度を、０．１〜１０℃／分の範囲に調整する。例えば冷却速度をより小さく選択すると、Ｃｕ相の硬度Ｈｍは小となり、［Ｈｍ／Ｈｏ］比を小とするのに有益である。
▲４▼溶浸後の接点に対して、再加熱処理を追加し、その温度を、５００〜１０７０℃の範囲、実質的には６５０〜７５０℃での再加熱処理温度を選択し、［Ｈｍ／Ｈｏ］比を小さく謂整する。
▲５▼溶浸後の接点に対して、再加圧力が４〜１０トン／ｃｍ²の範囲の再加圧処理を追加し、［Ｈｍ／Ｈｏ］比を小さく調整する。
▲６▼［Ｈｍ／Ｈｏ］比を更に微調整する際には、Ｃｕ相に対してはＣｒ，Ｔｉ，Ｖ，Ｂ，Ｎｂ，Ｔａより選ばれた１つを適宜量添加することによって、または第１の補助成分としてのＡｌ，Ｓｉの少なくとも一方を適宜量添加することによって、前記比率の微調整は可能である。これら▲１▼▲２▼▲３▼▲４▼▲５▼▲６▼などを適宜組合わせることによって［Ｈｍ／Ｈｏ］比を調整した接点を得た。
【０１２８】
（実施例３０〜３２、比較例９〜１０）
上述のように用意したＣｕ粉とＣｒ粉とを用いて、固相焼結法によって所定の［Ｈｍ／Ｈｏ］比を有する７５％Ｃｕ−残部Ｃｒ合金を製造した（実施例３０〜３２、比較例９〜１０）。
【０１２９】
[Ｈｍ／Ｈｏ］比を調整する為に、接点製造に際しては上記Ａ）Ｂ）Ｃ）Ｄ）の適宜選択又は組み合わせによって、１．０〜２．０（実施例３０〜３２）、２．６〜３．０（比較例９〜１０）の［Ｈｍ／Ｈｏ］比を有する接点を選出した。
【０１３０】
これらの接点を評価用真空バルブに搭載し、前記所定条件で再点弧発生頻度（×１０^-3％で示した数値）と遮断特性とを測定した。［Ｈｍ／Ｈｏ］比＝１．０の場合では、６台のバルブを評価したところ、再点弧発生頻度は、評価（Ｓ）を示し極めて良好な特性を発揮した。遮断特性も、２４．ｋＡの１０回遮断に成功し遮断特性も「合格」である。評価前の接点加工表面の観察によれば、Ｃｕ相部分は完全に均一に切削研磨された状況が見られ、極めて安定した接点表面状態を示し、Ｃｕ相の脱落、研磨傷などによる表面荒れは見られていない。評価後の接点の最表面層の顕微鏡的観察でも、最表面層領域からのＣｕ相の脱落はなかった（実施例３０）。なお［Ｈｍ／Ｈｏ］比が１．０未満の合金でも特性的には同等の良好な性能を発揮する。
【０１３１】
また、［Ｈｍ／Ｈｏ］比＝１．３とした場合では、再点弧発生頻度は、評価（Ａ〜Ｂ）を示し良好な特性を発揮した。遮断特性も２４ｋＡの１０回遮断に成功し「合格」である。Ｃｕ相部分はほぼ均一に切削研磨された状況が見られ、極めて安定した接点表面の加工状態を示し、Ｃｕ相の脱落、研磨傷などによる表面荒れは見られていない。評価後の接点の最表面層の顕微鏡的観察でも、最表面層領域からのＣｕ相の脱落はなかった（実施例３１）。
【０１３２】
更に、［Ｈｍ／Ｈｏ］比＝２．０とした場合でも、再点弧発生頻度は、評価（Ｃ）を示し良好な特性を発揮した。遮断特性も２０ｋＡの１０回遮断に成功し遮断特性も「合格」である。Ｃｕ相部分はほぼ均一に切削研磨された状況が見られ、Ｃｕ相の脱落、研磨傷などによる表面荒れはなく、極めて安定した接点表面状態を示している（実施例３２）。
【０１３３】
これに対して、［Ｈｍ／Ｈｏ］比＝２．６の場合では、再点弧発生頻度は、評価（Ｙ〜Ｚ）を示し再点弧特性に大幅な劣化が見られると共に大きなバラツキも示し好ましくない。遮断特性も、２０ｋＡの遮断テストに於いて多数の遮断不能を示し「不合格」である。遮断前の加工表面にはＣｕ相の脱落跡が観察されている。遮断後の接点面には局所的な荒れが存在している（比較例９）。
【０１３４】
また、［Ｈｍ／Ｈｏ］比＝３．０の場合でも、再点弧発生頻度は、評価（Ｚ）を示し再点弧特性に大幅な劣化が見られる。遮断特性も、２０ｋＡの遮断テストに於いて多数の遮断不能を示し「不合格」である。加工面の静耐圧値に大きなバラツキが見られている（比較例１０）。
【０１３５】
以上から、再点弧特性と遮断特性との両立に対して、［Ｈｍ／Ｈｏ］比の管理が極めて重要であると共に、［Ｈｍ／Ｈｏ］比を２．０以下の範囲を選択する時に目的を達する。
【０１３６】
（実施例３３〜３５、比較例１１〜１２）
前記実施例では、Ｃｕ−Ｃｒ合金中のＣｕの量を７５％に一定とした時の、［Ｈｍ／Ｈｏ］比を変動させた場合の、［Ｈｍ／Ｈｏ］比が再点弧特性と遮断特性に及ぼす効果を示したが、本発明技術ではＣｕ量は７５％に限ることなく、Ｃｕの量が９０〜１０％（実施例３３〜３５）に於いても効果を発揮する。
【０１３７】
すなわち、［Ｈｍ／Ｈｏ］比＝１．２〜１．４に一定とした時，Ｃｕ量が９０％の場合では、再点弧発生頻度は、評価（Ｂ〜Ｃ）を示し良好な特性を発揮した。遮断特性も、２４ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例３３）。最表面層の顕微鏡的観察では、加工面からのＣｕ相の脱落や加工傷も無く、評価後の接点面からもＣｕ相の脱落はなかった。
【０１３８】
Ｃｕ量が６０％の場合でも、再点弧発生頻度は、評価（Ｂ）を示し良好な特性を発揮した。遮断特性も、２０ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例３４）。
【０１３９】
Ｃｕ量が１０％の場合でも、再点弧発生頻度は、評価（Ａ〜Ｂ）を示し良好な特性を発揮した。遮断特性も、２０ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例３５）。最表面層の顕微鏡的観察では、加工面からのＣｕ相の脱落や加工傷も無く、評価後の接点面からのＣｕ相の脱落もなかった。
【０１４０】
これに対して、Ｃｕ量が９５％の場合では、再点弧発生頻度は、評価（Ｃ〜Ｙ）を示し再点弧特性に大幅な劣化が見られると共に大幅なバラツキも示し好ましくない。但し遮断特性は、２０ｋＡの遮断に成功し遮断特性では「合格」であったが、一部に溶着の発生が見られ総合的には目的達成に対して好ましくない（比較例１１）。
【０１４１】
一方、Ｃｕ量が５％の場合では、再点弧発生頻度は、評価（Ｙ〜Ｚ）を示し再点弧特性に大幅な劣化が見られる共に大福なバラツキも示し好ましくない。遮断特性も、２０ｋＡの遮断テストに於いて多数の遮断不能を示し「不合格」である。遮断特性の著しく低下していると共に遮断テスト中の温度上昇特性、遮断テスト後の接触抵抗特性の安定性に乏しい（比較例１２）。最表面層の顕微鏡的観察では、加工面上には著しい加工傷が見られた。この加工傷が原因となって静耐圧値が低下している。また加工時の機械的衝撃によってＣｕ相部分の一部に脱落が見られた。遮断評価後の接点面からもＣｕ相の脱落が認められた。
【０１４２】
以上から、Ｃｕ−Ｃｒ合金中のＣｕ相に関する［Ｈｍ／Ｈｏ］比を所定量に管理する本発明技術は、Ｃｕ−Ｃｒ合金中のＣｕ相の量が９０〜１０％の時にその効果を発揮する。
【０１４３】
（実施例３６〜４１）
前記実施例３０〜３５では、Ｃｕ−Ｃｒ合金中のＣｕ相中に存在する成分については、注目していなかったが、Ｃｕ−Ｃｒ合金中のＣｕ相に関する［Ｈｍ／Ｈｏ］比を管理する本発明技術は、Ｃｕ相中への所定量のＣｒ，Ｔｉ，Ｂ，Ｖ，Ｎｂ，Ｔａを含有したＣｕを使用したＣｕ（Ｃｒ，Ｔｉ，Ｂ，Ｖ，Ｎｂ，Ｔａのいずれか１つ）−Ｃｒ合金に対しても、再点弧特性、遮断特性が安定化する。
【０１４４】
すなわち、Ｃｕ−Ｃｒ合金中のＣｕの量を７５％に一定とした時、Ｃｕ相中に、０．１％のＣｒ成分を含有した７５％Ｃｕ接点では、再点弧発生頻度は、評価（Ａ）を示し良好な特性を発揮した。遮断特性も、２４．ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例３６）。
【０１４５】
Ｃｕ相中に、０．３％のＴｉを含有させた接点では、再点弧発生頻度は、評価（Ａ〜Ｂ）を示し良好な特性を発揮した。遮断特性も、２０ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例３７）。
【０１４６】
Ｃｕ相中に、０．５％のＢを含有させた接点では、再点弧発生頻度は、評価（Ａ〜Ｂ）を示し良好な特性を発揮した。遮断特性も、２４ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例３８）。
【０１４７】
Ｃｕ相中に、１．５％のＶを含有させた接点では、再点弧発生頻度は、評価（Ｂ）を示し良好な特性を発揮した。遮断特性も、２０ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例３９）。
【０１４８】
Ｃｕ相中に、１０％のＮｂを含有させた接点では、再点弧発生頻度は、評価（Ｂ〜Ｃ）を示し良好な特性を発揮した。遮断特性も、２４ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例４０）。
【０１４９】
Ｃｕ相中に、２０％のＴａを含有させた接点では、再点弧発生頻度は、評価（Ｂ〜Ｃ）を示し良好な特性を発揮した。遮断特性も、２４ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例４１）。
【０１５０】
実施例３６〜４１で示したように、Ｃｕ相中への所定量のＣｒ，Ｔｉ，Ｂ，Ｖ，Ｎｂ，Ｔａの添加は、Ｃｕ相の脱落を抑制し再点弧特性の安定化に寄与する。
【０１５１】
以上から、Ｃｕ−Ｃｒ合金中のＣｕ相に関する［Ｈｍ／Ｈｏ］比を所定量に管理する本発明技術は、Ｃｕ相中に所定量のＣｒ，Ｔｉ，Ｂ，Ｖ，Ｎｂ，Ｔａのいずれか１つを含有したＣｕを採用したＣｕ−Ｃｒ合金に対しても有効に発揮される。
【０１５２】
（実施例４２〜４５）
Ｃｕ−Ｃｒ合金中のＣｕ相に関する［Ｈｍ／Ｈｏ］比を管理する本発明技術は、Ｃｒ粒子中に所定量のＴｉ，Ｖ，Ｎｂ，Ｔａを含有したＣｒを使用したＣｕ−Ｃｒ（Ｔｉ，Ｖ，Ｎｂ，Ｔａのいずれか１つ）合金に対しても、再点弧特性、遮断特性が安定化する。
【０１５３】
すなわち、［Ｈｍ／Ｈｏ］比を１．２〜１．４に一定とした上で、Ｃｒ粒子中に０．５％のＴｉを含有させた接点では、再点弧発生頻度は、評価（Ａ〜Ｂ）を示し良好な特性を発揮した。遮断特性も、２４．ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例４２）。
【０１５４】
Ｃｒ粒子中に２．０％のＶを含有させた接点では、再点弧発生頻度は、評価（Ｂ）を示し良好な特性を発揮した。遮断特性も、２０ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例４３）。
【０１５５】
Ｃｒ粒子中に２５％のＮｂを含有させた接点では、再点弧発生頻度は、評価（Ｂ）を示し良好な特性を発揮した。遮断特性も、２４ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例４４）。
【０１５６】
Ｃｒ粒子中に５０％のＴａを含有させた接点では、再点弧発生頻度は、評価（Ｂ）を示し良好な特性を発揮した。遮断特性も、２４ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例４５）。
【０１５７】
Ｃｒ粒子中での所定量のＴｉ，Ｖ，Ｎｂ，Ｔａの存在効果は、Ｃｕ相とＣｒ粒子との界面に作用し合金全体としての耐消耗性や耐電圧特性を改善し、［Ｈｍ／Ｈｏ］比を所定量に管理する本発明技術との相乗的効果によって、再点弧発生頻度のバラツキ幅を圧縮し接点特性の安定化に寄与している。
【０１５８】
以上から、Ｃｕ−Ｃｒ合金中のＣｕ相に関する［Ｈｍ／Ｈｏ］比を所定量に管理する本発明技術は、Ｃｒ粒子中に所定量のＴｉ，Ｖ，Ｎｂ，Ｔａを含有したＣｒを採用したＣｕ−Ｃｒ（Ｔｉ，Ｖ，Ｎｂ，Ｔａのいずれか１つ）合金に対しても有効に発揮される。
【０１５９】
（実施例４６〜４７、比較例１３）
前記実施例３０〜４５では、０．１〜１５０μｍの平均粒子直径を有するＣｒ粒子が、全Ｃｒ粒子の９５％（容積％）以上（０．９５〜０．９９）を占める例についてその効果を示したが、本発明技術では、全Ｃｒ粒子中に占める０．１〜１５０μｍの平均粒子直径を有するＣｒ粒子は、９５％（容積％）以上のＣｕ−Ｃｒ合金の場合に限ることなく適応が可能である。
【０１６０】
すなわち、全Ｃｒ粒子中に占める平均粒子直径が、０．１〜１５０μｍのＣｒの比率が８５％（容積％）のＣｒを使用したＣｕ−Ｃｒ接点では、再点弧発生頻度は、評価（Ｂ）を示し良好な特性を発揮した。遮断特性も、２０ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例４６）。
【０１６１】
全Ｃｒ粒子中に占める平均粒子直径が、０．１〜１５０μｍのＣｒの比率が７５％（容積％）のＣｒを使用した接点では、再点弧発生頻度は、評価（Ｂ〜Ｃ）を示し良好な特性を発揮した。遮断特性も、２０ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例４７）。
【０１６２】
これに対して、全Ｃｒ粒子中に占める平均粒子直径が、０．１〜１５０μｍのＣｒの比率が５０％（容積％）のＣｒを使用した接点では、再点弧発生頻度は、評価（Ｃ〜Ｚ）を示し再点弧特性に大幅な劣化が見られると共に大幅なバラツキも示し好ましくない。遮断特性も、評価したバルブのうちの１本のみ２０ｋＡの遮断に成功しているが、他の５本の総てのバルブでは２０ｋＡの遮断不能多発し、バラツキが大で遮断特性は「不合格」である（比較例１３）。
【０１６３】
以上から、Ｃｕ−Ｃｒ合金中のＣｕ相に関する［Ｈｍ／Ｈｏ］比を所定量に管理する本発明技術は、全Ｃｒ粒子中に占める平均粒子直径の比率が７５％（容積％）以上のＣｒ粒子を採用したＣｕ−Ｃｒ合金に於いて有効に発揮される。
【０１６４】
（実施例４８〜５２、比較例１４）
Ｃｕ−Ｃｒ合金中のＣｒ粒子中の第１の補助成分として、１．０％以下のＡｌ，Ｓｉを含有したＣｒを使用した場合には、再点弧特性、遮断特性の安定化に有益である。
【０１６５】
すなわち、Ｃｒ粒子中に１．０％のＡｌを含有させた接点では、再点弧発生頻度は、評価（Ｃ）を示し良好な特性を発揮した。遮断特性も、２０ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例４８）。
【０１６６】
Ｃｒ粒子中に０．１％のＡｌを含有させた接点では、再点弧発生頻度は、評価（Ｂ）を示し良好な特性を発揮した。遮断特性も、２０ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例４９）。
【０１６７】
Ｃｒ粒子中に０．０１％のＡｌを含有させた接点では、再点弧発生頻度は、評価（Ｓ〜Ａ）を示し極めて良好な特性を発揮した。遮断特性も、３１．５ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例５０）。
【０１６８】
Ｃｒ粒子中に０．００１％のＡｌを含有させた接点では、再点弧発生頻度は、評価（Ａ）を示し極めて良好な特性を発揮した。遮断特性も、２０ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例５１）。
【０１６９】
Ｃｒ粒子中に０．０１％のＳｉを含有させた接点では、再点弧発生頻度は、評価（Ｓ〜Ａ）を示し極めて良好な特性を発揮した。遮断特性も、３１．５ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例５２）。
【０１７０】
いずれもＣｕ相の脱落や剥離がなく安定した接点面となっている。
【０１７１】
これに対して、Ｃｕ−Ｃｒ合金中のＣｒ粒子中の第１の補助成分として、１．５％のＡｌを含有したＣｒを使用した場合には、再点弧発生頻度は、評価（Ｚ）を示し再点弧特性に大幅な劣化が見られ好ましくない。遮断特性も、１０回の２４ｋＡ遮断中に８回、２０ｋＡ遮断中に２回の再点弧発生を記録し、遮断不能が多発し遮断特性は「不合格」である（比較例１４）。加工直後の接点面にはすでにＣｕ相の脱落が見られ、これが最初の再点弧発生の引き金となっている。
【０１７２】
以上から、Ｃｕ−Ｃｒ合金中のＣｕ相に関する［Ｈｍ／Ｈｏ］比を所定量に管理する本発明技術は、Ｃｒ粒子中の第１の補助成分として、１．０％以下のＡｌ，Ｓｉを含有したＣｒ粒子を採用したＣｕ−Ｃｒ合金に対しても適用が可能である。
【０１７３】
（実施例５３〜５８、比較例１５〜１６）
第２の補助成分として、１．０％以下のＢｉ，Ｓｂを含有したＣｕ−Ｃｒ合金を使用した場合には、再点粉特性、遮断特性の安定化に有益である。また他の第２の補助成分として、５．０％以下のＴｅ，Ｓｅ，Ｐｂを含有したＣｕ−Ｃｒ合金を使用した場合にも、再点弧特性、遮断特性の安定化に有益である。
【０１７４】
すなわち、Ｃｕ−Ｃｒ合金中の第２の補助成分として、０．１％のＢｉを含有させた接点では、再点弧発生頻度は、評価（Ｂ）を示し良好な特性を発揮した。遮断特性も、２４ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例５３）。
【０１７５】
Ｃｕ−Ｃｒ合金中の第２の補助成分として１．０％のＢｉを含有させた接点では、再点弧発生頻度は、評価（Ｂ〜Ｃ）を示し良好な特性を発揮した。遮断特性も、２０ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例５４）。
【０１７６】
Ｃｕ−Ｃｒ合金中の第２の補助成分として、０．２％のＳｂを含有させた接点では、再点弧発生頻度は、評価（Ｂ〜Ｃ）を示し良好な特性を発揮した。遮断特性も、２０ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例５５）。
【０１７７】
Ｃｕ−Ｃｒ合金中の第２の補助成分として、２．５％のＴｅを含有させた接点では、再点弧発生頻度は、評価（Ｂ〜Ｃ）を示し良好な特性を発揮した。遮断特性も、２０ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例５６）。
【０１７８】
Ｃｕ−Ｃｒ合金中の第２の補助成分として、５．０％のＴｅを含有させた接点では、再点弧発生頻度は、評価（Ｃ）を示し良好な特性を発揮した。遮断特性も、２０ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例５７）。
【０１７９】
Ｃｕ−Ｃｒ合金中の第２の補助成分として、２．５％のＳｅを含有させた接点では、再点弧発生頻度は、評価（Ｃ）を示し良好な特性を発揮した。遮断特性も、２０ｋＡの１０回遮断に成功し遮断特性も「合格」である（実施例５８）。
【０１８０】
また、Ｃｕ−Ｃｒ合金中の第２の補助成分として、０．２％のＰｂを含有させた接点でも同等の再点弧発生頻度および遮断特性を発揮し「合格」である。
【０１８１】
いずれもＣｕ相の脱落や剥離がなく安定した接点面となっている。
【０１８２】
これに対して、Ｃｕ−Ｃｒ合金中の第２の補助成分として、３．０％のＢｉを含有させた接点では、再点弧発生頻度は、評価（Ｙ〜Ｚ）を示し再点弧特性に大幅な劣化が見られ好ましくない。遮断特性も、２０ｋＡ以下の遮断で再点弧が多発し遮断特性は「不合格」である（比較例１５）。遮断テスト後の接点表面には著しい荒れが見られる。接触抵抗にもバラツキが見られた。
【０１８３】
Ｃｕ−Ｃｒ合金中の第２の補助成分として、８．０％のＴｅを含有させた接点では、再点弧発生頻度は、評価（Ｚ）を示し再点弧特性に大幅な劣化が見られれ好ましくない。遮断特性も、２０ｋＡの遮断に成功と２０ｋＡの遮断失敗が多発し遮断特性は「不合格」である（比較例１６）。遮断テスト後の接点表面には著しい荒れが見られる。接触抵抗にもバラツキが見られた。
【０１８４】
以上から、Ｃｕ−Ｃｒ合金中のＣｕ相に関する［Ｈｍ／Ｈｏ］比を所定量に管理する本発明技術は、Ｃｒ粒子中の第２の補助成分として、１．０％以下のＢｉ，Ｓｂを含有したＣｕ−Ｃｒ合金、または他の第２の補助成分として、５．０％以下のＴｅ，Ｓｅ，Ｐｂを含有したＣｕ−Ｃｒ合金に対しても適用が可能である。
【０１８５】
（その他の実施例）
焼結工程後若しくは焼結・溶浸工程後のＣｕ−Ｃｒを、非酸化性雰囲気中で、Ｃｕ−Ｃｒ合金中のＣｕ相の融解温度以下の温度またはＣｕ相の融解温度以上の温度で加熱し、これを常温にまで冷却することとし、この場合も焼結工程後若しくは焼結・溶浸工程後の、Ｃｕ−Ｃｒ合金中のＣｕ相の硬度値（マイクロビッカース硬さ値）をＨｍ、非酸化性雰囲気中で、Ｃｕ−Ｃｒ合金中のＣｕ相の融解温度以下の温度またはＣｕ相の融解温度以上の温度で加熱し、これを常温にまで冷却した時の、Ｃｕ−Ｃｒ合金中のＣｕ相の硬度値（マイクロビッカース硬さ値）をＨｏとした時の［Ｈｍ／Ｈｏ］比を、１．０〜２．０の範囲に調整することとしてもよい。
【０１８６】
このように、Ｃｕ−Ｃｒ接点材料の製造雰囲気として、非酸化性雰囲気を選択することにより、特に再点弧発生頻度の低減化を図ることができる。
【０１８７】
【発明の効果】
以上説明したように、本発明によれば、ＣｕＣｒ合金の再点弧特性を安定化させ電流遮断特性の優れた電力用真空遮断器の接点材料の製造方法を提供することができるので、その工業的価値は大である。
【図面の簡単な説明】
【図１】本発明に係る電力用真空遮断器の接点材料の実施例１〜１６及び比較例１〜４の評価条件を示す表図。
【図２】本発明に係る電力用真空遮断器の接点材料の実施例１７〜２９及び比較例５〜８の評価条件を示す表図。
【図３】本発明に係る電力用真空遮断器の接点材料の実施例１〜１６及び比較例１〜４の評価結果を示す表図。
【図４】本発明に係る電力用真空遮断器の接点材料の実施例１７〜２９及び比較例５〜８の評価結果を示す表図。
【図５】本発明に係る電力用真空遮断器の接点材料の実施例３０〜４５及び比較例９〜１２の評価条件を示す表図。
【図６】本発明に係る電力用真空遮断器の接点材料の実施例４６〜５８及び比較例１３〜１６の評価条件を示す表図。
【図７】本発明に係る電力用真空遮断器の接点材料の実施例３０〜４５及び比較例９〜１２の評価結果を示す表図。
【図８】本発明に係る電力用真空遮断器の接点材料の実施例４６〜５８及び比較例１３〜１６の評価結果を示す表図。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a contact material for a power vacuum circuit breaker comprising a vacuum valve or the like having excellent interruption characteristics and re-ignition suppression characteristics. Manufacturing method About.
[0002]
[Prior art]
The contact of the vacuum valve that cuts off the current in high vacuum using the arc diffusibility in vacuum is composed of two fixed and movable contacts facing each other.
[0003]
In addition to the three basic requirements of large current interruption performance, withstand voltage performance, and resistance to welding, suppression of the occurrence of a re-ignition phenomenon is an important requirement for a vacuum circuit breaker.
[0004]
However, because some of these requirements are contradictory, it is impossible to satisfy all the requirements with a single metal species. For this reason, in many contact materials that are in practical use, a combination of two or more elements that complement each other in deficient performance can be used for specific purposes such as for high currents and high withstand voltages. Selection of contact materials suitable for the application has been carried out, and vacuum valves having excellent characteristics have been developed. However, in reality, a vacuum valve that sufficiently satisfies the increasing demand has not yet been obtained.
[0005]
For example, a Cu—Cr alloy (Japanese Patent Publication No. 45-35101) containing about 50 wt% of Cr is known as a contact for the purpose of interrupting a large current. This alloy realizes high voltage and large current interruption due to the effect that Cr itself retains vapor pressure characteristics substantially the same as Cu and exhibits a powerful gas getter action. It is often used as a contact that can be compatible.
[0006]
Since this alloy uses highly active Cr, contact materials can be manufactured (sintering process, etc.) while paying sufficient attention to the selection of raw material powder, mixing of impurities, atmosphere control, etc. It is a contact product while considering processing from the material to the contact piece.
[0007]
However, there are cases where the occurrence of re-ignition triggers and lowers the breaking performance, and the improvement is desired.
[0008]
[Problems to be solved by the invention]
CuCr contacts have relatively smooth damage characteristics even after current interruption, mainly due to the closeness of their vapor pressure characteristics at high temperatures, and stable electrical characteristics (stable contact) Resistant characteristics, excellent interruption characteristics, re-ignition suppression, etc.) However, in recent years, as a result of routine adaptation to circuits where higher current interruption and higher voltage may be applied, the surface condition of a new article processed as a contact, damage to the contact surface after current interruption Depending on the situation, re-ignition has been triggered. In other words, on the contact surface that is abnormally damaged or consumed due to current interruption during processing, it may cause abnormal increase in contact resistance or abnormal temperature during the next steady-state current switching or withstand voltage. It shows a defect and contributes to the occurrence of re-ignition.
[0009]
According to research, the re-ignition characteristics and interruption characteristics of CuCr alloys depend on the variation of Cr content in the alloy, the particle size distribution of Cr particles, the degree of segregation of Cr particles, the degree of vacancies present in the alloy, etc. Turned out to be. It has also been found that the re-ignition characteristics and the breaking characteristics of the CuCr alloy depend on the change of the surface state of the Cu phase in the alloy, particularly before and after breaking.
[0010]
However, despite the progress of optimization, the above-mentioned recent adaptation situation still shows variations, and a vacuum valve having both characteristics has become necessary.
[0011]
The present invention has been made in view of the above points, and its object is to stabilize the re-ignition characteristic of the CuCr alloy and to provide a contact material for a power vacuum circuit breaker having excellent current interruption characteristics. Manufacturing method Is to provide.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, the present invention according to claim 1 is a conductive component comprising a Cu phase composed of Cu or a Cu alloy containing Cu as a main component; From Cr The contact material of the vacuum circuit breaker for electric power which consists of Cu-Cr alloy containing 10 to 90 weight% Cu comprised by the arc-resistant component which consists of In the manufacturing method, first, the Cu—Cr alloy is heated to 1030 ° C. to 1080 ° C., which is just below the melting temperature of the Cu phase, and is cooled to room temperature. The Cr Vickers hardness value Hr of the Cr particles is obtained, and then Cr powder having a particle size of 0.1 to 150 μm and Cu powder having a particle size of 44 to 62 μm are mixed at a predetermined ratio and added at a predetermined value. After pressing, sintering at a predetermined temperature or pressurizing a predetermined amount of the Cr powder at a predetermined value, sintering at 800-1400 ° C., infiltrating the Cu lump at 1100-1400 ° C., and cooling to room temperature at a predetermined rate When the micro Vickers hardness value of Cr particles in the Cu—Cr alloy is Hs, the [Hs / Hr] ratio is in the range of 1.0 to 1.6 at the time of pressurization. Pressure, temperature during sintering and speed during cooling Adjusted one or more of Contact materials for vacuum circuit breakers for electric power Manufacturing method It is.
[0013]
Here, the hardness value Hs of the Cr particles at the time of manufacturing the contact material (after the sintering process or after the sintering / infiltration process) is the content of the raw material Cr, the heat treatment conditions selected at the time of sintering and infiltration, and the contact material processing. The degree of residual distortion at the time is determined in relation to each other. For example, the Vickers hardness of Hs shows a value in the vicinity of 200.
[0014]
By the way, when this contact material is incorporated as a vacuum valve and actually operated, the contact surface gradually changes (softens) at the time of steady current switching or when an accident current is interrupted, and finally a constant hardness value H _B In the meantime, the hardness value Hs near the first Vickers hardness of 200 is greatly reduced. Hardness value H when it finally becomes constant after actually operating the vacuum valve _B And the hardness value Hr of the Cr particles when heated to a temperature T1 immediately below the melting temperature of the Cu phase and then cooled to room temperature, _B , Hr) was found to show an approximate hardness value.
[0015]
By the way H _B This measurement is disadvantageous because it is economically expensive and time-consuming due to the fact that a vacuum valve is manufactured to measure the current, and that the current must be cut off and opened / closed. _B And Hr by using the above property that approximates Hr and Hr. _B Substituting for H, which is difficult to measure _B Instead of this, it is advantageous that Hr, which is easy to measure, can change the state of softening of the contact surface at the time of steady-state current switching or accident current interruption.
[0016]
Further, as the hardness value Hs of the Cr particles at the time of manufacturing the contact material is larger and the difference from the hardness value Hr when cooled to room temperature is larger (that is, the [Hs / Hr] ratio is larger), re-ignition occurs. It was also found that the frequency tends to be large. When a contact with a [Hs / Hr] ratio exceeding 1.6 is selected, the difference in hardness between the Cr particles in the Cu-Cr alloy and the Cu phase becomes large, and due to the difference in hardness during mechanical finishing of the contact A stable machined surface state cannot be obtained, which is undesirable for the targeted low reignition.
[0018]
Here, the hardness value of Cr when heat-treated at a temperature lower than the temperature T1 immediately below the melting temperature of the Cu phase (a temperature lower than 1030 ° C.) and the hardness value H of Cr after the current interruption / opening / closing operation are performed. _B Does not match. Therefore, if the hardness value of Cr when heat-treated at a temperature lower than T1 is used, the relationship between the [Hs / Hr] ratio and the re-ignition occurrence frequency cannot be sufficiently dealt with, and product management Cannot be done.
[0026]
Also The amount of Cu phase in the Cu-Cr alloy is 10 weight If it is less than%, the current interruption characteristic will be significantly reduced. The amount of Cu phase is 90 weight If it exceeds%, it will be difficult to ensure a [Hs / Hr] ratio of 1.6 or less, and the frequency of re-ignition will increase.
[0035]
The present invention according to claim 2 is a conductive component comprising a Cu phase composed of Cu or a Cu alloy containing Cu as a main component, From Cr The contact material of the vacuum circuit breaker for electric power made of a Cu-Cr alloy containing 10 to 90 wt% Cu composed of an arc resistant component consisting of In the production method, first, the Cu—Cr alloy is heated to 1030 ° C. to 1080 ° C., which is just below the melting temperature of the Cu phase, and cooled to room temperature. The Cu-phase micro Vickers hardness value Ho is obtained, and then Cr powder having a particle size of 0.1 to 150 μm and Cu powder having a particle size of 44 to 62 μm are mixed at a predetermined ratio and pressed at a predetermined value. Then, sintering at a predetermined temperature, or pressurizing a predetermined amount of the Cr powder at a predetermined value, sintering at 800 to 1400 ° C., infiltrating a Cu lump at 1100 to 1400 ° C., and cooling to room temperature at a predetermined speed. When the micro Vickers hardness value of the Cu phase in the Cu-Cr alloy is Hm, the [Hm / Ho] ratio is in the range of 1.0 to 2.0. One of pressure, temperature during sintering and speed during cooling Adjusted the above Contact materials for vacuum circuit breakers for electric power Manufacturing method It is.
[0036]
Here, the hardness value Hm of the Cu phase at the time of manufacturing the contact material (after the sintering process or after the sintering / infiltration process) depends on the heat treatment conditions (such as cooling rate) selected at the time of sintering and infiltration and contact processing. The degree of residual strain at the time is determined in relation to each other, and the Vickers hardness of Hm is a value in the vicinity of 100.
[0037]
By the way, when this contact material is incorporated as a vacuum valve and actually operated, the contact surface gradually changes (softens) due to arc heat at the time of opening and closing of the steady current and interruption of the accident current, and finally, the constant hardness value Hb In the meantime, the hardness value Hm near the initial Vickers hardness of 100 changes (decreases) significantly. The hardness value Hb when the vacuum valve is actually operated and finally becomes constant, and the hardness value Ho of the Cu phase when heated to the normal temperature T1 immediately below the melting temperature of the Cu phase and then cooled to room temperature. Was compared, it was found that both (Hb, Ho) showed almost similar hardness values.
[0038]
By the way, in measuring Hb, Hb and Ho are disadvantageous because of the disadvantages of economic and time burden due to the fact that a vacuum valve must be manufactured and the actual current must be cut off or opened and closed. Utilizing the above property that is an approximate value, it replaces Hb with Ho, that is, the contact surface at the time of steady-state current switching or fault current interruption by Ho that is easy to measure instead of Hb that is difficult to measure It is possible and beneficial to change the softening situation.
[0039]
In addition, the hardness value Hm of the Cu phase after sintering and infiltration of the contact material is large, and the difference between the hardness value Ho of the Cu phase when cooled to room temperature (that is, the Hm / Ho ratio) is larger. It was also found that the frequency of re-ignition tends to be large. When a contact with a [Hm / Ho] ratio exceeding 2.0 is selected, the difference in hardness between the Cu phase and the Cr particles in the Cu-Cr alloy becomes large, and due to the difference in hardness during mechanical finishing of the contact A stable machined surface state cannot be obtained, which is undesirable for the targeted low reignition.
[0041]
Here, the hardness value of the Cu phase when heat-treated at a temperature lower than the temperature T1 immediately below the melting temperature of the Cu phase (a temperature lower than 1030 ° C.), and the hardness value Hb of the Cu phase after the current interruption / opening / closing operation Does not match. Therefore, if the hardness value of the Cu phase when heat-treated at a temperature lower than T1 is used, the relationship between the [Hm / Ho] ratio and the re-ignition occurrence frequency cannot be sufficiently dealt with. Quality control becomes impossible.
[0049]
Also The amount of Cu phase in the Cu-Cr alloy is 10 weight If it is less than%, the current interruption characteristic will be significantly reduced. The amount of Cu phase is 90 weight If it exceeds 50%, the contact surface wears up and the frequency of re-ignition increases.
[0058]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail.
[0059]
Regarding the material state of Cu-Cr contacts and the occurrence of reignition, the inventors have observed the following knowledge regarding the relationship between the material characteristics before and after interruption and the occurrence of variations in reignition. .
{Circle around (1)} Cu—Cr contacts are generally finished by polishing, grinding or cutting means. However, even if the contents of Cu—Cr (manufacturing conditions, processing conditions, etc.) are constant, there is still variation in the occurrence of re-ignition. As a result of the observations by the inventors, Cr particles fall off the contact surface, Cu phase part falls, flow (Cu covers the Cr particles) and peeling, Cr particle edge chipping, scratches, and other various kinds Existed. One of the reasons was a correlation between the difference in workability on the contact surface, especially in the micro region, that is, the variation in re-ignition and the difference in hardness uniformity in the micro region. This trend was observed between production lots of contact materials and even in the micro-region of a single contact.
(2) Furthermore, it was recognized that the frequency of re-ignition gradually stabilizes to a substantially constant value as the steady current switching operation and the accident current interruption operation progress. This situation is considered to indicate a phenomenon in which the contact surface gradually changes (softens) due to arc heat and finally reaches a certain hardness value.
[0060]
Therefore, the hardness value H of the Cr particles at the contact point, which has become an almost constant value by applying the fault current interruption operation many times to the actual vacuum valve. _B The hardness value Hb of the Cu phase was measured. The temperature immediately below the melting temperature of the Cu phase portion of the contact is selected, and after sufficiently heating at that temperature, the hardness value Hr of the Cr particles in the contact and the hardness value Ho of the Cu phase when cooled to room temperature In contrast, the two values are almost approximate values (H _B = Hr, Hb = Ho).
(3) Further, regarding the hardness value of the Cr particles, the hardness value (micro Vickers hardness value) of the Cr particles in the Cu-Cr alloy after the sintering process or after the sintering / infiltration process is defined as Cu. -When the hardness value (micro Vickers hardness value) of the Cr particles in the Cu-Cr alloy is Hr when heated to a temperature just below the melting temperature of the Cu phase in the Cr alloy and cooled to room temperature. It was recognized that the higher the difference between Hs and Hr (that is, the greater the [Hs / Hr] ratio), the greater the frequency of re-ignition. When a contact having a [Hs / Hr] ratio exceeding 1.6 is selected, the difference in hardness between the Cr particles in the Cu-Cr alloy and the Cu phase becomes large, and a preferable processing surface is obtained when the contact is mechanically finished. The state is not obtained, which is not preferable for the target low reignition. On the other hand, when a contact having a [Hs / Hr] ratio of 1.6 or less, preferably 1.3 or less is selected, the difference in hardness between the Cr particles and the Cu phase becomes small. As a result of obtaining a preferable processed surface state, always obtaining a constant and stable surface state, and reducing the stagnation and concentration of the arc, the local abnormal evaporation phenomenon on the contact surface and the reduction of surface roughness, etc. It contributes to the improvement of the breaking characteristics with the benefit of low reignition.
[0061]
Further, regarding the hardness value of the Cu phase, the Cu phase hardness value (micro Vickers hardness value) in the Cu—Cr alloy immediately after the sintering process or immediately after the sintering / infiltration process is defined as Hm. When the hardness value (micro Vickers hardness value) of the Cu phase in the Cu-Cr alloy when heated to a temperature just below the melting temperature of the Cu phase inside and cooled to room temperature is Ho, Hm is It was found that the greater the difference from Ho (ie, the higher the [Hm / Ho] ratio), the greater the frequency of re-ignition. If a contact with a [Hm / Ho] ratio exceeding 2.0 is selected, the difference in hardness between the Cr particles and the Cu phase becomes large, and a preferable processed surface state cannot be obtained during mechanical finishing of the contact. It is not preferable for the target low reignition. On the other hand, when a contact having a [Hm / Ho] ratio of 2.0 or less, preferably 1.3 or less is selected, the difference in hardness between the Cr particles and the Cu phase is small, and the mechanical finishing of the contact is performed. A preferable machined surface state is obtained, and a constant and stable surface state is always obtained. As a result, arc stagnation and concentration are reduced. As a result, local abnormal evaporation of the Cu phase portion of the contact surface is prevented, and surface roughness is prevented. Mitigation will contribute to the improvement of the breaking characteristics as well as the benefits of low reignition.
{Circle around (4)} When an external magnetic field (for example, a longitudinal magnetic field) is applied to such a contact, the arc generated by interruption spreads and spreads uniformly on the contact surface, and the current interruption characteristics can be improved. According to observation, when the current value above a certain value is interrupted, the arc tends to stagnate at one or more places where it cannot be predicted, but the contact with an [Hs / Hr] ratio of 1.6 or less. , The degree tends to be lower than that of the contact exceeding 1.6, and the contact whose [Hm / Ho] ratio is 2.0 or less is more than that of the contact exceeding 2.0. Tend to be low and excellent. Eventually, a part of the contact is abnormally melted to reach the breaking limit. In addition, the metal vapor generated by instantaneous explosive evaporation due to abnormal melting remarkably hinders the insulation recoverability of the vacuum circuit breaker that was in the process of opening, leading to further deterioration of the breaking limit. Furthermore, abnormal melting creates huge droplets and causes contact surface roughness, leading to a decrease in withstand voltage characteristics, an increase in the rate of re-ignition, and abnormal consumption of materials. Since it is impossible to predict where the arc that contributes to these phenomena will stagnate on the contact surface, surface conditions that allow the generated arc to move and diffuse without stagnation and means to promote movement diffusion It is desirable to give to the contact. In the present invention, as a desirable condition, the [Hs / Hr] ratio relating to Cr particles in the Cu—Cr alloy or the [Hm / Ho] ratio relating to the Cu phase in the Cu—Cr alloy is important.
[0062]
[1] Example of adjusting [Hs / Hr] ratio
As described above, the stabilization of the contact characteristics of the CuCr alloy depends on the variation of the Cr amount in the alloy, the particle size of the Cr particles, the particle size distribution, the degree of Cr segregation, the degree of vacancies present in the alloy, etc. However, in addition to the above, it has been found that the behavior of Cr particles in the CuCr alloy is extremely important in order to further stabilize the re-ignition characteristics. In other words, it was found that the frequency of re-ignition of the vacuum valve requires attention to the change in the hardness of Cr in the alloy before and after the interruption.
[0063]
Therefore, first, examples and comparative examples for producing contact materials by adjusting the [Hs / Hr] ratio for Cr particles in the Cu—Cr alloy will be described. In addition, the conditions of the trial manufacture of an Example and a comparative example are shown in FIG.1 and FIG.2, and the evaluation result of these Examples and a comparative example is shown in FIG.3 and FIG.4.
[0064]
(Evaluation of blocking characteristics)
A flat contact with a surface roughness of 5 μm and a convex contact with the same surface roughness and a curvature radius of 100R are opposed to each other, and both contacts have a degree of vacuum of 10 having an opening / closing mechanism. ^-3 Pa. Attach it to the detachable vacuum breaker experimental device which is evacuated below, and turn on and off 10 times with load 40kg, 7.2kV-20kA ~ 31.5kA, and "pass" when the occurrence of welding and re-ignition is slight The operation was repeated 10 times, and the occurrence of frequent welding and re-ignition was defined as “failed”.
[0065]
(Evaluation of re-ignition characteristics)
The frequency of re-ignition when the 6 kV × 500 A circuit was interrupted 1000 times was measured for six vacuum valves. Incidence (× 10 ^-3 (%)) Is 0.3 or less evaluation S, the range of 0.3-1 is evaluated A, the range of 1-3 is evaluated B, the range of 3-10 is evaluated C, the range of 10-100 is evaluated Y , 100 or more was evaluated as Z.
[0066]
(Measurement of hardness)
The Cu phase portion and Cr particles were individually loaded using a micro Vickers hardness tester with a load of 10 to 25 gr. Measured with
[0067]
(Adjustment of [Hs / Hr] ratio)
The contacts can be manufactured by either solid-phase sintering or solid-phase / infiltration methods. Here, an example is shown in which a Cr skeleton is manufactured and Cu is infiltrated into the voids. A Cu powder having a particle diameter in the range of 44 to 62 μm (95 to 99% of the total Cu powder) was prepared. Cu having a particle diameter approximate to this was prepared from Cr powder having a particle diameter in the range of 0.1 to 150 μm (occupying 95 to 99% in the total Cr powder).
[0068]
The hardness value (micro Vickers hardness value) of Cr particles in the Cu-Cr alloy after the sintering process or after the sintering / infiltration process is Hs, and the melting temperature of the Cu phase in the Cu-Cr alloy is [Hs / Hr] ratio when the hardness value (micro Vickers hardness value) of the Cr particles in the Cu-Cr alloy is Hr when heated to just below the temperature and cooled to room temperature is as follows: It adjusted as follows.
(1) The pressure applied to the Cr powder when forming the Cr powder is 0 to 8 tons / cm. ² Adjustment is made within the range of (the pressure is 0 when Cr is put in a container and sintered as it is). For example, when the ratio is increased, a high pressure value is selected.
{Circle around (2)} The sintering temperature at the time of producing the Cr skeleton is adjusted in the range of 800 to 1400 ° C. For example, when the ratio is increased, a lower temperature is selected from this temperature range.
(3) The temperature at which Cu is infiltrated into the Cr skeleton is adjusted in the range of 1100 to 1400 ° C. For example, when the ratio is increased, a lower infiltration temperature is selected.
(4) Adjust the cooling rate when cooling to room temperature after infiltration to the range of 0.1 to 10 ° C./min. For example, when the ratio is increased, a small cooling rate is selected.
(5) A reheating treatment is added to the contact after sintering, sintering and infiltration, and the temperature is adjusted in the range of 500 to 1070 ° C. For example, when increasing the ratio, for example, a lower reheating temperature at 650 to 750 ° C. is selected.
(6) Re-pressurization treatment is added to the contacts after sintering, sintering and infiltration, and the re-pressing pressure is 4 to 10 tons / cm. ² Adjust within the range. For example, when the ratio is increased, a higher repressing pressure is selected so that the relative density before the repressurizing process is increased.
(7) When the [Hs / Hr] ratio is further finely adjusted, an appropriate amount of one selected from Cr, Ti, V, B, Nb, and Ta is added to the Cu phase.
(8) The ratio can be finely adjusted by adding an appropriate amount of at least one of Ti, V, Nb, and Ta, or Al or Si as the first auxiliary component, to the Cr particles. Is possible.
[0069]
By appropriately combining these (1), (2), (3), (4), (5), (6), (7), (8), etc., a contact having an adjusted [Hs / Hr] ratio was obtained.
[0070]
(Examples 1-3, Comparative Examples 1-2)
Using the Cu powder and Cr powder prepared as described above, a 75% Cu-residual Cr alloy having a predetermined [Hs / Hr] ratio was manufactured by a solid phase / infiltration method (Examples 1 to 3, Comparative Examples 1-2). In order to adjust the [Hs / Hr] ratio, when manufacturing the contacts, 1.0 to 1.6 (Examples 1 to 3), 1.9 to Contacts having a [Hs / Hr] ratio of 2.3 (Comparative Examples 1 and 2) were selected.
[0071]
These contacts are mounted on the evaluation vacuum pulp, and the re-ignition occurrence frequency (× 10 ^-3 (Numerical value expressed in%) and blocking characteristics were measured. In the case of the [Hs / Hr] ratio = 1.0, when six valves were evaluated, the re-ignition occurrence frequency showed evaluation (S to A) and exhibited good characteristics. As for the interruption characteristic, the interruption of 10 times of 31.5 kA was successful and the interruption characteristic was also “pass”. According to the observation of the contact processed surface before the evaluation, the state of being cut and polished almost uniformly without distinction between the Cr particle portion and the Cu phase portion was observed, showing an extremely stable contact surface state, and the removal of the Cr particles and the polishing scratches. No surface roughness due to the above has been observed. Even in the microscopic observation of the outermost surface layer of the contact after the evaluation, the Cr particles did not fall off from the outermost surface layer region (Example 1).
[0072]
Further, in the case of [Hs / Hr] ratio = 1.3, the re-ignition occurrence frequency showed evaluation (A to B) and exhibited good characteristics. The interruption characteristics are 10 interruptions at 24 kA, and the interruption characteristic is “pass”. The state of being cut and polished almost uniformly with no distinction between the Cr particle portion and the Cu phase portion is seen, showing a very stable contact surface processing state, and no surface roughness due to Cr particle dropping, polishing scratches, etc. is seen ( Example 2).
[0073]
Furthermore, even when the [Hs / Hr] ratio = 1.6, the re-ignition occurrence frequency showed evaluation (C) and exhibited good characteristics. The interruption characteristics are 10 interruptions at 20 kA, and the interruption characteristic is “pass”. A state of being cut and polished almost uniformly with no distinction between the Cr particle portion and the Cu phase portion was observed, and there was no surface roughness due to the drop of Cr particles, polishing scratches, etc., indicating an extremely stable contact surface state (Example 3) ).
[0074]
On the other hand, in the case of [Hs / Hr] ratio = 1.9, the re-ignition occurrence frequency shows evaluation (C to Y), and the re-ignition characteristic is greatly deteriorated and also shows a large variation. It is not preferable. The interruption characteristics are “failed” indicating a large number of interruptions in the interruption test of 20 kA. Dropped traces of Cr particles are observed on the processed surface before blocking. Local roughness exists on the contact surface after the interruption (Comparative Example 1).
[0075]
Further, in the case of the [Hs / Hr] ratio = 2.3, the re-ignition occurrence frequency shows the evaluation (Z), and the re-ignition characteristic is greatly deteriorated. The interruption characteristics are “failed” indicating a large number of interruptions in the interruption test of 20 kA. A large variation is observed in the static pressure resistance value of the processed surface (Comparative Example 2).
[0076]
From the above, the management of the [Hs / Hr] ratio is extremely important for coexistence of the re-ignition characteristic and the interruption characteristic, and the purpose is to select the same ratio in the range of 1.0 to 1.6. Reach.
[0077]
(Examples 4-6, Comparative Examples 3-4)
In the above example, the effect on the re-ignition characteristic and the interruption characteristic when the ratio of [Hs / Hr] was changed when the amount of Cu in the Cu-Cr alloy was fixed to 75% was shown. The technique of the present invention is not limited to the Cu content of 75%, but is effective even when the Cu content is 90 to 10% (Examples 4 to 6).
[0078]
That is, when the [Hs / Hr] ratio is constant at 1.4, when the Cu content is 90%, the re-ignition occurrence frequency shows the evaluation (C) and exhibits good characteristics. As for the interruption characteristic, the interruption was successful 10 times at 20 kA, and the interruption characteristic was “pass” (Example 4).
[0079]
Even when the amount of Cu was 50%, the re-ignition occurrence frequency showed evaluation (B to C) and exhibited good characteristics. As for the interruption characteristic, the interruption was successful 10 times at 24 kA, and the interruption characteristic was “pass” (Example 5).
[0080]
Even when the amount of Cu was 10%, the re-ignition occurrence frequency showed evaluation (AB) and exhibited good characteristics. As for the interruption characteristic, the interruption was successful 10 times at 20 kA, and the interruption characteristic was “pass” (Example 6).
[0081]
On the other hand, when the amount of Cu is 95%, the re-ignition occurrence frequency shows an evaluation (C to Y), and re-ignition characteristics are greatly deteriorated and large variation is not preferable. However, although the interruption characteristic succeeded in interruption of 20 kA and was "pass" in the interruption characteristic, it is not preferable for the achievement of the object comprehensively (Comparative Example 3).
[0082]
On the other hand, when the amount of Cu is 5%, the re-ignition occurrence frequency shows an evaluation (Y to Z), and the re-ignition characteristic is greatly deteriorated and also shows a large variation. The interruption characteristics are “failed” indicating a large number of interruptions in the interruption test of 20 kA. The interruption characteristics were significantly reduced and the temperature rise characteristics during the interruption test and the contact resistance characteristics after the interruption test were markedly reduced (Comparative Example 4).
[0083]
(Examples 7 to 12)
In Examples 1-6, the Cu phase in the Cu-Cr alloy showed its effect for an example in which Cu containing 0.01% Cr component was used. This component exhibits an effect without being limited to 0.01% Cr.
[0084]
That is, when the amount of Cu in the Cu-Cr alloy is constant at 75%, the re-ignition occurrence frequency is evaluated at a 75% Cu contact containing 0.2% Cr component in the Cu phase ( S to A) and very good characteristics were exhibited. As for the interruption characteristic, the interruption of 10 times at 31.5 kA was successful, and the interruption characteristic was “pass” (Example 7).
[0085]
In the contact containing 0.5% Ti in the Cu phase, the re-ignition occurrence frequency showed evaluation (B to C) and exhibited good characteristics. As for the interruption characteristic, the interruption was successful 10 times at 20 kA, and the interruption characteristic was “pass” (Example 8).
[0086]
In the contact containing 1.0% V in the Cu phase, the re-ignition occurrence frequency showed evaluation (B to C) and exhibited good characteristics. As for the interruption characteristic, the interruption was successful 10 times at 20 kA, and the interruption characteristic was “pass” (Example 9).
[0087]
In the contact containing 1.0% B in the Cu phase, the re-ignition occurrence frequency showed evaluation (B to C) and exhibited good characteristics. As for the interruption characteristic, the interruption was successful 10 times at 20 kA, and the interruption characteristic was “pass” (Example 10).
[0088]
In the contact containing 10% Nb in the Cu phase, the re-ignition occurrence frequency showed evaluation (B) and exhibited good characteristics. As for the interruption characteristic, the interruption was successful 10 times at 24 kA and the interruption characteristic was “pass” (Example 10).
[0089]
In the contact containing 20% Ta in the Cu phase, the re-ignition occurrence frequency showed evaluation (B) and exhibited good characteristics. As for the interruption characteristic, the interruption was successful 10 times at 24 kA and the interruption characteristic was “pass” (Example 12).
[0090]
(Examples 13 to 16)
When Cr containing Ti, V, Nb, and Ta is used as a component in the Cr particles in the Cu-Cr alloy, it is useful for stabilizing the re-ignition characteristic and the interruption characteristic.
[0091]
That is, in the contact containing 1.0% Ti in the Cr particles, the re-ignition occurrence frequency showed evaluation (S to A) and exhibited very good characteristics. As for the cutoff characteristic, the cutoff of 10 times of 31.5 kA was successful, and the cutoff characteristic was “pass” (Example 13).
[0092]
In the contact containing 2.0% V in the Cr particles, the re-ignition occurrence frequency showed evaluation (B) and exhibited good characteristics. As for the blocking characteristics, the blocking was successful 10 times at 24 kA, and the blocking characteristics were “pass” (Example 14).
[0093]
In the contact containing 25% Nb in the Cr particles, the re-ignition occurrence frequency showed evaluation (A to B) and exhibited good characteristics. As for the cutoff characteristic, the cutoff was successful 10 times at 24 kA, and the cutoff characteristic was “pass” (Example 15).
[0094]
In the contact containing 50% Ta in the Cr particles, the re-ignition occurrence frequency showed evaluation (B) and exhibited good characteristics. As for the blocking characteristics, the blocking was successful 10 times at 24 kA, and the blocking characteristics were “pass” (Example 16).
[0095]
(Examples 17 to 18, Comparative Example 5)
In Examples 1 to 16, the effect was shown for an example in which Cr particles having an average particle diameter of 0.1 to 150 μm accounted for 95% (volume%) or more of the total Cr particles. The Cr particles having an average particle diameter of 0.1 to 150 μm in the particles exhibit an effect without being limited to 95% or more.
[0096]
That is, in the contact using Cr having a ratio of Cr having an average particle diameter of 0.1 to 150 μm occupying in all Cr particles and having 85% (volume%), the re-ignition occurrence frequency shows a favorable evaluation (B). Demonstrated the characteristics. As for the interruption characteristic, the interruption was successful 10 times at 24 kA and the interruption characteristic was “pass” (Example 17).
[0097]
For contacts using Cr with a ratio of 75% (volume%) of Cr having an average particle diameter of 0.1 to 150 μm occupying in all Cr particles, the re-ignition occurrence frequency shows evaluation (B to C) and is good Demonstrated the characteristics. As for the interruption characteristic, the interruption was successful 10 times at 20 kA, and the interruption characteristic was “pass” (Example 18).
[0098]
On the other hand, the re-ignition occurrence frequency is evaluated (B to Z) in a contact using Cr with a ratio of Cr having an average particle diameter of 0.1 to 150 μm in all Cr particles and a requisite 50% (volume%) Cr. ) And re-ignition characteristics are significantly deteriorated and large variation is also undesirable. As for the blocking characteristics, there are a success in blocking 20 kA and a failure in blocking 20 kA, the variation is large, and the blocking characteristic is “fail” (Comparative Example 5).
[0099]
(Examples 19 to 23, Comparative Example 6)
When Cr containing 1.0% or less of Al and Si is used as the first auxiliary component in the Cr particles in the Cu-Cr alloy, it is beneficial for stabilizing the re-ignition characteristic and the interruption characteristic. is there.
[0100]
That is, at the contact where 1.0% Al was contained in the Cr particles, the re-ignition occurrence frequency showed evaluation (A to B) and exhibited good characteristics. As for the blocking characteristic, the blocking was successful 10 times at 24 kA, and the blocking characteristic was “pass” (Example 19).
[0101]
In the contact where 0.1% Al was contained in the Cr particles, the re-ignition occurrence frequency showed evaluation (S to A) and exhibited good characteristics. The interruption characteristic was also successfully interrupted 10 times at 31.5 kA, and the interruption characteristic was “pass” (Example 20).
[0102]
In the contact where 0.01% Al was contained in the Cr particles, the re-ignition occurrence frequency showed evaluation (S to A) and exhibited very good characteristics. The interruption characteristic was also successfully interrupted 10 times at 31.5 kA, and the interruption characteristic was “pass” (Example 21).
[0103]
In the contact where 0.001% Al was contained in the Cr particles, the re-ignition occurrence frequency showed evaluation (SA) and exhibited very good characteristics. The interruption characteristic was also successfully interrupted 10 times at 31.5 kA, and the interruption characteristic was “pass” (Example 22).
[0104]
In the contact where 0.01% Si was contained in the Cr particles, the re-ignition occurrence frequency showed evaluation (SA) and exhibited extremely good characteristics. The interruption characteristics were also successfully interrupted 10 times at 31.5 kA, and the interruption characteristics were “pass” (Example 23).
[0105]
On the other hand, in the contact in which 1.5% Al is contained in the Cr particles, the re-ignition occurrence frequency shows an evaluation (Y to Z), which is not preferable. The shut-off characteristics were “failed” because there was a valve that re-ignited 8 times out of 10 in the shut-off test of 31.5 kA (Comparative Example 6).
[0106]
(Examples 24-29, Comparative Examples 7-8)
When a Cu—Cr alloy containing 1.0% or less of Bi and Sb is used as the second auxiliary component, it is beneficial for stabilizing the re-ignition characteristic and the interruption characteristic. Further, when a Cu—Cr alloy containing 5.0% or less of Te, Se, Pb is used as another second auxiliary component, it is useful for stabilizing the re-ignition characteristic and the interruption characteristic.
[0107]
That is, in the contact containing 0.1% Bi as the second auxiliary component in the Cu-Cr alloy, the re-ignition occurrence frequency showed evaluation (B) and exhibited good characteristics. The blocking characteristics were also successfully blocked 10 times at 24 kA, and the blocking characteristics were “pass” (Example 24).
[0108]
In the contact containing 1.0% Bi as the second auxiliary component in the Cu—Cr alloy, the re-ignition occurrence frequency showed evaluation (B to C) and exhibited good characteristics. As for the cutoff characteristic, the cutoff of 10 times at 20 kA was successful, and the cutoff characteristic was “pass” (Example 25).
[0109]
In the contact containing 0.2% Sb as the second auxiliary component in the Cu-Cr alloy, the re-ignition occurrence frequency showed evaluation (B to C) and exhibited good characteristics. As for the cutoff characteristic, the cutoff was successful 10 times at 20 kA, and the cutoff characteristic was “pass” (Example 26).
[0110]
In the contact containing 2.5% Te as the second auxiliary component in the Cu-Cr alloy, the re-ignition occurrence frequency showed evaluation (B to C) and exhibited good characteristics. As for the interruption characteristic, the interruption was successful 10 times at 20 kA, and the interruption characteristic was “pass” (Example 27).
[0111]
In the contact containing 5.0% Te as the second auxiliary component in the Cu-Cr alloy, the re-ignition occurrence frequency showed evaluation (C) and exhibited good characteristics. As for the cutoff characteristic, the cutoff was successful 10 times at 20 kA, and the cutoff characteristic was “pass” (Example 28).
[0112]
In the contact containing 2.5% Se as the second auxiliary component in the Cu-Cr alloy, the re-ignition occurrence frequency showed evaluation (B to C) and exhibited good characteristics. As for the blocking characteristic, the blocking was successful 10 times at 20 kA, and the blocking characteristic was “pass” (Example 29).
[0113]
Further, even a contact containing 0.2% Pb as the second auxiliary component exhibits the same re-ignition occurrence frequency and interruption characteristics and is “pass”.
[0114]
In the contact containing 3.0% Bi as the second auxiliary component in the Cu-Cr alloy, the re-ignition occurrence frequency shows evaluation (Y to Z), and the re-ignition characteristic is greatly deteriorated. It is not preferable to be seen. As for the interruption characteristics, re-ignition frequently occurs at interruptions of 20 kA or less, and the interruption characteristics are “fail” (Comparative Example 7). Significant roughness is observed on the contact surface after the interruption test. There was also a variation in contact resistance.
[0115]
In the contact containing 8.0% Te as the second auxiliary component in the Cu-Cr alloy, the re-ignition occurrence frequency indicates evaluation (Y to Z), and the re-ignition characteristic is greatly deteriorated. In addition to being seen, large variation is also undesirable. As for the blocking characteristics, there are a success in blocking 20 kA and a failure in blocking 20 kA, the variation is large, and the blocking characteristic is “fail” (Comparative Example 8). Significant roughness is observed on the contact surface after the interruption test. There was also a variation in contact resistance.
[0116]
(Other examples)
Heat Cu-Cr after the sintering process or after the sintering / infiltration process in a non-oxidizing atmosphere at a temperature below the melting temperature of the Cu phase in the Cu-Cr alloy or above the melting temperature of the Cu phase. In this case, the hardness value (micro Vickers hardness value) of the Cr particles in the Cu-Cr alloy after the sintering process or after the sintering / infiltration process is Hs, In a non-oxidizing atmosphere, heating at a temperature below the melting temperature of the Cu phase in the Cu-Cr alloy or a temperature above the melting temperature of the Cu phase, and cooling this to room temperature, It is good also as adjusting [Hs / Hr] ratio in the range of 1.0-1.6 when the hardness value (micro Vickers hardness value) of Cr particle | grains is set to Hr.
[0117]
Thus, by selecting a non-oxidizing atmosphere as the manufacturing atmosphere of the Cu—Cr contact material, it is possible to particularly reduce the frequency of re-ignition.
[0118]
[2] Example of adjusting [Hm / Ho] ratio
Further, as described above, for stabilizing the contact characteristics of the CuCr alloy, the state of the Cu phase in the alloy (surface roughness, degree of vacancies), the size of the Cu phase (grain size, degree of particle size distribution analysis), etc. In addition to the above, it has been found that the behavior of the Cu phase in the Cu—Cr alloy is extremely important for further stabilization of the re-ignition characteristics. That is, it has been found that the frequency of re-ignition of the vacuum valve needs to pay attention to the change in hardness of Cu in the alloy before and after the interruption.
[0119]
Then, the Example and comparative example which adjust the [Hm / Ho] ratio regarding the Cu phase in a Cu-Cr alloy and manufacture a contact material are demonstrated. In addition, the conditions of the trial manufacture of an Example and a comparative example are shown in FIG.5 and FIG.6, and the evaluation result of these Examples and a comparative example is shown in FIG.7 and FIG.8.
[0120]
(Evaluation of blocking characteristics)
In the case of the embodiment for adjusting the [Hm / Ho] ratio, the same surface roughness as that of the flat contact having a surface roughness of 5 μm is obtained, as in the case of the embodiment for adjusting the [Hs / Hr] ratio. The degree of vacuum is 10 with an open / close mechanism that faces the convex contact with a radius of curvature of 100R. ^-3 Pa. Attach it to the evacuated and removable vacuum shut-off experimental device below, and repeat loading and shut-off 10 times with a load of 40 kg, 7.2 kV-20 kA to 31.5 kA. " The charging / shut-off was repeated 10 times, and the occurrence of re-ignition or welding frequently was defined as “fail”.
[0121]
(Evaluation of re-ignition characteristics)
The frequency of re-ignition when the 6 kV × 500 A circuit was interrupted 1000 times was measured for six vacuum valves. Incidence (× 10 ^-3 (%)) Is 0.3 or less evaluation S, the range from 0.3 to 1 is evaluated A, the range from 1 to 3 is evaluated B, the range from 3 to 10 is evaluated C, the range from 10 to 100 is evaluated Y and 100 or more were evaluated as Z.
[0122]
(Measurement of hardness)
The Cu phase portion was loaded with a load of 10 to 25 gr. Using a micro Vickers hardness tester. Measured with
[0123]
([Hm / Ho] adjustment)
The contacts can be manufactured by either solid phase sintering or sintering / infiltration. The hardness value (micro Vickers hardness value) of the Cu phase in the Cu-Cr alloy after the sintering process or after the sintering / infiltration process is set to a temperature just below the melting temperature of the Cu phase in the Hm, Cu-Cr alloy. The contact having a predetermined [Hm / Ho] ratio when the hardness value (micro Vickers hardness value) of the Cu phase in the Cu-Cr alloy when heated and cooled to room temperature is Ho, Adjustments were made as follows.
(1) In the production using the former solid-phase sintering method, Cr powder having a particle diameter in the range of 0.1 to 150 μm (95 to 99% of all Cr powder) was prepared and approximated to this. As Cu having a particle diameter, Cu powder in the range of 44 to 62 μm (95 to 99% of the total Cu powder) is prepared. After mixing and molding a predetermined ratio of Cu and Cr, for example, solid-phase sintering is performed at 1030 ° C. to produce a Cu—Cr alloy. In addition, although it can employ | adopt with respect to the alloy of the whole range whose Cu amount in a Cu-Cr alloy is 5-95%, it is mainly with respect to the alloy whose range of Cu is 60-95% and 5-45%. Applied.
[0124]
A) The pressure applied to the mixed powder when forming the Cu-Cr mixed powder is 0 to 8 tons / cm. ² The [Hm / Ho] ratio is adjusted to be small within the range of (the pressure is 0 when Cr is put in a container and sintered as it is).
[0125]
B) The cooling rate when cooling to room temperature after solid phase sintering is adjusted to a range of 0.1 to 10 ° C./min. For example, if the cooling rate is selected to be smaller, the hardness value Hm of the Cu phase becomes smaller, which is beneficial for reducing the [Hm / Ho] ratio.
[0126]
C) Re-pressing force of 4 to 10 tons / cm with respect to the contact after solid-phase sintering ² The re-pressurization process in the range of is added, and the [Hm / Ho] ratio is adjusted to be small.
[0127]
D) When the [Hm / Ho] ratio is further finely adjusted, an appropriate amount of one selected from Cr, Ti, V, B, Nb, Ta is added to the Cu phase, or The ratio can be finely adjusted by adding an appropriate amount of at least one of Al and Si as one auxiliary component. A contact having an adjusted [Hm / Ho] ratio was obtained by appropriately combining A), B), C) and D).
(2) In the production employing the latter infiltration method, Cr powder having a particle diameter in the range of 0.1 to 150 μm (occupying 95 to 99% in the total Cr powder) is prepared. A Cu lump for infiltration is prepared. For example, a Cr skeleton is produced at 1200 ° C. using this Cr, and then Cu is infiltrated into the gap to produce a Cu—Cr alloy. In addition, it applied to the alloy whose Cu amount in a Cu-Cr alloy is 45 to 60% of range.
(1) The pressure applied to the Cr powder when forming the Cr powder is 0 to 8 tons / cm. ² Adjustment is made within the range of (the pressure is 0 when Cr is put in a container and sintered as it is). For example, when the ratio is increased, a high pressure value is selected.
(2) The temperature at which Cu is infiltrated into the Cr skeleton is adjusted in the range of 1100 to 1400 ° C.
(3) The cooling rate when cooling to room temperature after infiltration is adjusted to a range of 0.1 to 10 ° C./min. For example, if the cooling rate is selected to be smaller, the hardness Hm of the Cu phase becomes smaller, which is beneficial for reducing the [Hm / Ho] ratio.
(4) A reheating treatment is added to the contact after infiltration, and a reheating treatment temperature in the range of 500 to 1070 ° C., substantially 650 to 750 ° C. is selected, and [Hm / Ho] ratio is made small and so-called.
(5) The re-pressing force is 4 to 10 tons / cm against the contact after infiltration. ² The re-pressurization process in the range of is added, and the [Hm / Ho] ratio is adjusted to be small.
(6) When the [Hm / Ho] ratio is further finely adjusted, an appropriate amount of one selected from Cr, Ti, V, B, Nb and Ta is added to the Cu phase, or The ratio can be finely adjusted by adding an appropriate amount of at least one of Al and Si as the first auxiliary component. By appropriately combining these (1), (2), (3), (4), (5), and (6), a contact having an adjusted [Hm / Ho] ratio was obtained.
[0128]
(Examples 30 to 32, Comparative Examples 9 to 10)
Using the Cu powder and Cr powder prepared as described above, a 75% Cu-residual Cr alloy having a predetermined [Hm / Ho] ratio was manufactured by solid-phase sintering (Examples 30 to 32, comparison) Examples 9-10).
[0129]
In order to adjust the [Hm / Ho] ratio, 1.0 to 2.0 (Examples 30 to 32), 2.6 by appropriately selecting or combining the above A), B), C) and D) when manufacturing contacts. Contacts having a [Hm / Ho] ratio of ˜3.0 (Comparative Examples 9 to 10) were selected.
[0130]
These contacts are mounted on an evaluation vacuum valve, and the re-ignition frequency (× 10 ^-3 (Numerical value expressed in%) and blocking characteristics were measured. In the case of the [Hm / Ho] ratio = 1.0, when six valves were evaluated, the re-ignition occurrence frequency showed evaluation (S) and exhibited extremely good characteristics. The interruption characteristic is also 24. The kA is successfully cut off 10 times, and the cut-off characteristics are also “pass”. According to the observation of the contact processed surface before evaluation, the Cu phase portion was found to be completely evenly polished and polished, showing an extremely stable contact surface state, and surface roughness due to Cu phase dropping, polishing scratches, etc. Not seen. Even in the microscopic observation of the outermost surface layer of the contact after evaluation, the Cu phase did not fall off from the outermost surface layer region (Example 30). In addition, even an alloy having a [Hm / Ho] ratio of less than 1.0 exhibits excellent performance equivalent in characteristics.
[0131]
When [Hm / Ho] ratio = 1.3, the re-ignition occurrence frequency showed evaluation (A to B) and exhibited good characteristics. The interruption characteristic was “passed” after successful interruption at 24 kA 10 times. The Cu phase portion was found to be cut and polished almost uniformly, showing a very stable contact surface processing state, and no surface roughness due to loss of Cu phase, polishing scratches, etc. was observed. Even in the microscopic observation of the outermost surface layer of the contact after the evaluation, the Cu phase did not fall off from the outermost surface layer region (Example 31).
[0132]
Furthermore, even when the [Hm / Ho] ratio was 2.0, the re-ignition occurrence frequency showed evaluation (C) and exhibited good characteristics. The blocking characteristic was also successfully blocked 10 times at 20 kA, and the blocking characteristic was “pass”. The Cu phase portion was found to have been cut and polished almost uniformly, and there was no surface roughness due to dropout of the Cu phase, polishing scratches, etc., indicating a very stable contact surface state (Example 32).
[0133]
On the other hand, in the case of the [Hm / Ho] ratio = 2.6, the re-ignition occurrence frequency indicates evaluation (Y to Z), and the re-ignition characteristic is significantly deteriorated and also shows a large variation. It is not preferable. The interruption characteristics are “failed” indicating a large number of interruptions in the interruption test of 20 kA. Cu phase drop-out traces are observed on the processed surface before blocking. Local roughness exists on the contact surface after the interruption (Comparative Example 9).
[0134]
Further, even when the [Hm / Ho] ratio = 3.0, the re-ignition occurrence frequency shows the evaluation (Z), and the re-ignition characteristics are significantly deteriorated. The interruption characteristics are “failed” indicating a large number of interruptions in the interruption test of 20 kA. A large variation is observed in the static pressure resistance value of the processed surface (Comparative Example 10).
[0135]
From the above, the management of the [Hm / Ho] ratio is extremely important for coexistence of the re-ignition characteristic and the interruption characteristic, and the purpose is to select a range of the [Hm / Ho] ratio of 2.0 or less. Reach.
[0136]
(Examples 33-35, Comparative Examples 11-12)
In the above embodiment, when the amount of Cu in the Cu—Cr alloy is constant at 75%, the [Hm / Ho] ratio is changed when the [Hm / Ho] ratio is changed. Although the effect on the characteristics has been shown, the present invention technique is not limited to the Cu content of 75%, and the effect is exhibited even when the Cu content is 90 to 10% (Examples 33 to 35).
[0137]
That is, when the [Hm / Ho] ratio is constant at 1.2 to 1.4, when the amount of Cu is 90%, the re-ignition occurrence frequency shows evaluation (B to C) and has good characteristics. Demonstrated. As for the blocking characteristics, the blocking was successful 10 times at 24 kA, and the blocking characteristics were “pass” (Example 33). In the microscopic observation of the outermost surface layer, there was no Cu phase dropping off from the processed surface and no processing flaws, and there was no Cu phase falling off from the contact surface after evaluation.
[0138]
Even when the amount of Cu was 60%, the re-ignition occurrence frequency showed evaluation (B) and exhibited good characteristics. As for the cutoff characteristic, the cutoff was successful 10 times at 20 kA, and the cutoff characteristic was “pass” (Example 34).
[0139]
Even when the amount of Cu was 10%, the re-ignition occurrence frequency showed evaluation (AB) and exhibited good characteristics. As for the cutoff characteristic, the cutoff was successful 10 times at 20 kA, and the cutoff characteristic was “pass” (Example 35). In the microscopic observation of the outermost surface layer, there was no loss of Cu phase from the processed surface and no processing scratches, and there was no loss of Cu phase from the contact surface after evaluation.
[0140]
On the other hand, when the amount of Cu is 95%, the re-ignition occurrence frequency shows an evaluation (C to Y), and the re-ignition characteristic is greatly deteriorated and also shows a large variation, which is not preferable. However, the blocking characteristic was successful in blocking 20 kA and was “passed” in the blocking characteristic, but the occurrence of welding was observed in part, which is not preferable for achieving the object comprehensively (Comparative Example 11).
[0141]
On the other hand, when the amount of Cu is 5%, the re-ignition occurrence frequency shows an evaluation (Y to Z), and the re-ignition characteristic is greatly deteriorated, and a large variation is unfavorable. The interruption characteristics are “failed” indicating a large number of interruptions in the interruption test of 20 kA. The breaking characteristics are remarkably lowered and the temperature rise characteristics during the breaking test and the stability of the contact resistance characteristics after the breaking test are poor (Comparative Example 12). In the microscopic observation of the outermost surface layer, remarkable processing flaws were observed on the processed surface. Due to this processing flaw, the static pressure resistance value is lowered. Further, a part of the Cu phase part was dropped due to mechanical impact during processing. The Cu phase was also removed from the contact surface after the interruption evaluation.
[0142]
From the above, the present invention technique for managing the [Hm / Ho] ratio for the Cu phase in the Cu—Cr alloy to a predetermined amount exhibits its effect when the amount of the Cu phase in the Cu—Cr alloy is 90 to 10%. To do.
[0143]
(Examples 36 to 41)
In Examples 30 to 35, attention was not paid to the components present in the Cu phase in the Cu—Cr alloy, but the [Hm / Ho] ratio for the Cu phase in the Cu—Cr alloy is managed. Inventive technology is Cu using Cu containing a predetermined amount of Cr, Ti, B, V, Nb, Ta in Cu phase (any one of Cr, Ti, B, V, Nb, Ta) − The re-ignition characteristic and the interruption characteristic are also stabilized for the Cr alloy.
[0144]
That is, when the amount of Cu in the Cu-Cr alloy is constant at 75%, the re-ignition occurrence frequency is evaluated at a 75% Cu contact containing 0.1% Cr component in the Cu phase ( A) and good characteristics were exhibited. The interruption characteristic is also 24. The kA was successfully cut off 10 times and the cut-off characteristic was “pass” (Example 36).
[0145]
In the contact containing 0.3% Ti in the Cu phase, the re-ignition occurrence frequency showed evaluation (A to B) and exhibited good characteristics. As for the cutoff characteristic, the cutoff was successful 10 times at 20 kA, and the cutoff characteristic was “pass” (Example 37).
[0146]
In the contact containing 0.5% B in the Cu phase, the re-ignition occurrence frequency showed evaluation (A to B) and exhibited good characteristics. As for the cutoff characteristic, the cutoff was successful 10 times at 24 kA, and the cutoff characteristic was “pass” (Example 38).
[0147]
In the contact containing 1.5% V in the Cu phase, the re-ignition occurrence frequency showed evaluation (B) and exhibited good characteristics. As for the blocking characteristic, the blocking was successful 10 times at 20 kA, and the blocking characteristic was “pass” (Example 39).
[0148]
In the contact containing 10% Nb in the Cu phase, the re-ignition occurrence frequency showed evaluation (B to C) and exhibited good characteristics. As for the blocking characteristics, the blocking was successful 10 times at 24 kA, and the blocking characteristics were also “pass” (Example 40).
[0149]
In the contact containing 20% Ta in the Cu phase, the re-ignition occurrence frequency showed evaluation (B to C) and exhibited good characteristics. As for the cutoff characteristic, the cutoff was successful 10 times at 24 kA, and the cutoff characteristic was “pass” (Example 41).
[0150]
As shown in Examples 36 to 41, addition of a predetermined amount of Cr, Ti, B, V, Nb, and Ta into the Cu phase suppresses the Cu phase from dropping and contributes to stabilization of the re-ignition characteristics. To do.
[0151]
From the above, the technology of the present invention for managing the [Hm / Ho] ratio related to the Cu phase in the Cu—Cr alloy to a predetermined amount is any one of the predetermined amount of Cr, Ti, B, V, Nb, Ta in the Cu phase. This is also effective for Cu-Cr alloys employing Cu containing one.
[0152]
(Examples 42 to 45)
The technology of the present invention for managing the [Hm / Ho] ratio related to the Cu phase in the Cu—Cr alloy uses Cu—Cr (Ti, Ti) using Cr containing a predetermined amount of Ti, V, Nb, Ta in the Cr particles. Any one of V, Nb, and Ta) also stabilizes the re-ignition characteristic and the interruption characteristic.
[0153]
That is, the re-ignition occurrence frequency is evaluated (A) at a contact having a [Hm / Ho] ratio constant at 1.2 to 1.4 and containing 0.5% Ti in the Cr particles. ~ B) and good characteristics were exhibited. The interruption characteristic is also 24. The kA was successfully cut off 10 times, and the cut-off characteristic was “pass” (Example 42).
[0154]
In the contact where 2.0% V was contained in the Cr particles, the re-ignition occurrence frequency showed evaluation (B) and exhibited good characteristics. As for the cutoff characteristic, the cutoff was successful 10 times at 20 kA, and the cutoff characteristic was “pass” (Example 43).
[0155]
In the contact containing 25% Nb in the Cr particles, the re-ignition occurrence frequency showed evaluation (B) and exhibited good characteristics. The interruption characteristic was also successfully interrupted 10 times at 24 kA and the interruption characteristic was “pass” (Example 44).
[0156]
In the contact containing 50% Ta in the Cr particles, the re-ignition occurrence frequency showed evaluation (B) and exhibited good characteristics. As for the blocking characteristics, the blocking was successful 10 times at 24 kA, and the blocking characteristics were also “pass” (Example 45).
[0157]
The presence effect of a predetermined amount of Ti, V, Nb, and Ta in the Cr particles acts on the interface between the Cu phase and the Cr particles to improve the wear resistance and withstand voltage characteristics of the entire alloy, and [Hm / Ho ] By synergistic effects with the present invention technology that manages the ratio to a predetermined amount, the variation width of the re-ignition occurrence frequency is compressed, contributing to stabilization of the contact characteristics.
[0158]
From the above, the present technology for managing the [Hm / Ho] ratio related to the Cu phase in the Cu—Cr alloy to a predetermined amount employs Cr containing a predetermined amount of Ti, V, Nb, Ta in the Cr particles. This is also effective for Cu—Cr (any one of Ti, V, Nb, Ta) alloys.
[0159]
(Examples 46 to 47, Comparative Example 13)
In Examples 30 to 45, the effect is obtained in the case where Cr particles having an average particle diameter of 0.1 to 150 μm occupy 95% (volume%) or more (0.95 to 0.99) of all Cr particles. As shown, in the technology of the present invention, Cr particles having an average particle diameter of 0.1 to 150 μm occupying in all Cr particles are not limited to the case of 95% (volume%) or more of Cu—Cr alloy. Is possible.
[0160]
That is, in the case of Cu-Cr contacts using Cr having an average particle diameter of 0.1 to 150 μm and a ratio of Cr of 85% (volume%) in all Cr particles, the re-ignition occurrence frequency is evaluated (B ) And exhibited good characteristics. As for the blocking characteristics, the blocking was successful 10 times at 20 kA, and the blocking characteristics were also “pass” (Example 46).
[0161]
For contacts using Cr with an average particle diameter of 0.1 to 150 μm and a ratio of Cr of 75% (volume%) in the total Cr particles, the frequency of re-ignition indicates evaluation (B to C). Good characteristics were demonstrated. As for the cutoff characteristic, the cutoff was successful 10 times at 20 kA, and the cutoff characteristic was “pass” (Example 47).
[0162]
On the other hand, the re-ignition occurrence frequency is evaluated (C) at the contact using Cr having an average particle diameter of 0.1 to 150 μm in all Cr particles and a ratio of Cr of 50% (volume%). ~ Z), re-ignition characteristics are significantly deteriorated and a large variation is also undesirable. Also, only one of the evaluated valves has succeeded in blocking 20 kA, but all the other five valves are not able to block 20 kA frequently. (Comparative Example 13).
[0163]
From the above, the technology of the present invention for managing the [Hm / Ho] ratio related to the Cu phase in the Cu—Cr alloy to a predetermined amount has a ratio of the average particle diameter in the total Cr particles of 75% (volume%) or more. It is effectively exhibited in Cu-Cr alloy using particles.
[0164]
(Examples 48 to 52, Comparative Example 14)
When Cr containing 1.0% or less of Al and Si is used as the first auxiliary component in the Cr particles in the Cu-Cr alloy, it is beneficial for stabilizing the re-ignition characteristic and the interruption characteristic. is there.
[0165]
That is, in the contact where 1.0% Al was contained in the Cr particles, the re-ignition occurrence frequency showed evaluation (C) and exhibited good characteristics. As for the cutoff characteristic, the cutoff was successful 10 times at 20 kA, and the cutoff characteristic was “pass” (Example 48).
[0166]
In the contact where 0.1% Al was contained in the Cr particles, the re-ignition occurrence frequency showed evaluation (B) and exhibited good characteristics. As for the cutoff characteristic, the cutoff of 10 times at 20 kA was successful, and the cutoff characteristic was “pass” (Example 49).
[0167]
In the contact where 0.01% Al was contained in the Cr particles, the re-ignition occurrence frequency showed evaluation (S to A) and exhibited very good characteristics. The interruption characteristics were also successfully interrupted 10 times at 31.5 kA, and the interruption characteristics were “pass” (Example 50).
[0168]
In the contact containing 0.001% Al in the Cr particles, the re-ignition occurrence frequency showed evaluation (A) and exhibited very good characteristics. As for the cutoff characteristic, the cutoff was successful 10 times at 20 kA, and the cutoff characteristic was “pass” (Example 51).
[0169]
In the contact where 0.01% Si was contained in the Cr particles, the re-ignition occurrence frequency showed evaluation (SA) and exhibited extremely good characteristics. The interruption characteristics were also successfully interrupted 10 times at 31.5 kA, and the interruption characteristics were “pass” (Example 52).
[0170]
In both cases, there is no Cu phase dropout or peeling, and the contact surface is stable.
[0171]
On the other hand, when Cr containing 1.5% Al is used as the first auxiliary component in the Cr particles in the Cu-Cr alloy, the re-ignition occurrence frequency is evaluated (Z). The re-ignition characteristics are greatly deteriorated, which is not preferable. As for the interruption characteristics, the occurrence of re-ignition was recorded 8 times during 10 interruptions of 24 kA and 2 times during the interruption of 20 kA, and the interruption characteristics frequently occurred and the interruption characteristics were “fail” (Comparative Example 14). The Cu phase has already dropped out on the contact surface immediately after processing, and this is the trigger for the first re-ignition.
[0172]
From the above, the technology of the present invention for managing the [Hm / Ho] ratio related to the Cu phase in the Cu—Cr alloy to a predetermined amount includes 1.0% or less of Al and Si as the first auxiliary component in the Cr particles. The present invention can also be applied to a Cu-Cr alloy employing the contained Cr particles.
[0173]
(Examples 53 to 58, Comparative Examples 15 to 16)
When a Cu—Cr alloy containing 1.0% or less of Bi and Sb is used as the second auxiliary component, it is beneficial for stabilizing the re-spotting characteristics and the barrier characteristics. Further, when a Cu—Cr alloy containing 5.0% or less of Te, Se, Pb is used as another second auxiliary component, it is useful for stabilizing the re-ignition characteristic and the interruption characteristic.
[0174]
That is, in the contact containing 0.1% Bi as the second auxiliary component in the Cu-Cr alloy, the re-ignition occurrence frequency showed evaluation (B) and exhibited good characteristics. As for the cutoff characteristic, the cutoff was successful 10 times at 24 kA, and the cutoff characteristic was “pass” (Example 53).
[0175]
In the contact containing 1.0% Bi as the second auxiliary component in the Cu—Cr alloy, the re-ignition occurrence frequency showed evaluation (B to C) and exhibited good characteristics. As for the cutoff characteristic, the cutoff was successful 10 times at 20 kA, and the cutoff characteristic was “pass” (Example 54).
[0176]
In the contact containing 0.2% Sb as the second auxiliary component in the Cu-Cr alloy, the re-ignition occurrence frequency showed evaluation (B to C) and exhibited good characteristics. As for the cutoff characteristic, the cutoff was successful 10 times at 20 kA, and the cutoff characteristic was “pass” (Example 55).
[0177]
In the contact containing 2.5% Te as the second auxiliary component in the Cu-Cr alloy, the re-ignition occurrence frequency showed evaluation (B to C) and exhibited good characteristics. As for the cutoff characteristic, the cutoff was successful 10 times at 20 kA, and the cutoff characteristic was “pass” (Example 56).
[0178]
In the contact containing 5.0% Te as the second auxiliary component in the Cu-Cr alloy, the re-ignition occurrence frequency showed evaluation (C) and exhibited good characteristics. As for the blocking characteristic, the blocking was successful 10 times at 20 kA, and the blocking characteristic was “pass” (Example 57).
[0179]
In the contact containing 2.5% Se as the second auxiliary component in the Cu-Cr alloy, the re-ignition occurrence frequency showed evaluation (C) and exhibited good characteristics. As for the blocking characteristics, the blocking was successful 10 times at 20 kA, and the blocking characteristics were “pass” (Example 58).
[0180]
In addition, even a contact containing 0.2% Pb as the second auxiliary component in the Cu—Cr alloy exhibits the same re-ignition occurrence frequency and interruption characteristics and is “pass”.
[0181]
In both cases, there is no Cu phase dropout or peeling, and the contact surface is stable.
[0182]
On the other hand, in the contact containing 3.0% Bi as the second auxiliary component in the Cu-Cr alloy, the re-ignition occurrence frequency indicates evaluation (Y to Z) and the re-ignition characteristic. However, it is not preferable because of significant deterioration. As for the interruption characteristic, re-ignition frequently occurs at interruption of 20 kA or less, and the interruption characteristic is “fail” (Comparative Example 15). Significant roughness is observed on the contact surface after the interruption test. There was also a variation in contact resistance.
[0183]
In the contact containing 8.0% Te as the second auxiliary component in the Cu-Cr alloy, the re-ignition occurrence frequency shows the evaluation (Z), and the re-ignition characteristic is greatly deteriorated. It is not preferable. As for the interruption characteristics, the success of the interruption of 20 kA and the failure of interruption of 20 kA occur frequently, and the interruption characteristic is “fail” (Comparative Example 16). Significant roughness is observed on the contact surface after the interruption test. There was also a variation in contact resistance.
[0184]
From the above, the technology of the present invention for managing the [Hm / Ho] ratio related to the Cu phase in the Cu—Cr alloy to a predetermined amount has Bi and Sb of 1.0% or less as the second auxiliary component in the Cr particles. The present invention can also be applied to Cu-Cr alloys containing Cu or Cr containing 5.0% or less of Te, Se, Pb as other second auxiliary components.
[0185]
(Other examples)
Heat Cu-Cr after the sintering process or after the sintering / infiltration process in a non-oxidizing atmosphere at a temperature below the melting temperature of the Cu phase in the Cu-Cr alloy or above the melting temperature of the Cu phase. In this case, the hardness value (micro Vickers hardness value) of the Cu phase in the Cu—Cr alloy after the sintering process or after the sintering / infiltration process is Hm, In a non-oxidizing atmosphere, heating at a temperature below the melting temperature of the Cu phase in the Cu-Cr alloy or a temperature above the melting temperature of the Cu phase, and cooling this to room temperature, The [Hm / Ho] ratio when the hardness value of the Cu phase (micro Vickers hardness value) is Ho may be adjusted to a range of 1.0 to 2.0.
[0186]
Thus, by selecting a non-oxidizing atmosphere as the manufacturing atmosphere of the Cu—Cr contact material, it is possible to particularly reduce the frequency of re-ignition.
[0187]
【The invention's effect】
As described above, according to the present invention, the contact material for the vacuum circuit breaker for electric power that stabilizes the re-ignition characteristic of the CuCr alloy and has excellent current interruption characteristics. Manufacturing method Therefore, its industrial value is great.
[Brief description of the drawings]
FIG. 1 is a table showing evaluation conditions of Examples 1 to 16 and Comparative Examples 1 to 4 of contact materials of a power circuit breaker according to the present invention.
FIG. 2 is a table showing the evaluation conditions of Examples 17 to 29 and Comparative Examples 5 to 8 of the contact material of the power vacuum circuit breaker according to the present invention.
FIG. 3 is a table showing evaluation results of Examples 1 to 16 and Comparative Examples 1 to 4 of contact materials of the power vacuum circuit breaker according to the present invention.
FIG. 4 is a table showing the evaluation results of Examples 17 to 29 and Comparative Examples 5 to 8 of the contact material of the power vacuum circuit breaker according to the present invention.
FIG. 5 is a table showing the evaluation conditions of Examples 30 to 45 and Comparative Examples 9 to 12 of contact materials for a power vacuum circuit breaker according to the present invention.
FIG. 6 is a table showing the evaluation conditions of Examples 46 to 58 and Comparative Examples 13 to 16 of the contact material of the power vacuum circuit breaker according to the present invention.
FIG. 7 is a table showing evaluation results of Examples 30 to 45 and Comparative Examples 9 to 12 of contact materials of the power vacuum circuit breaker according to the present invention.
FIG. 8 is a table showing the evaluation results of Examples 46 to 58 and Comparative Examples 13 to 16 of contact materials of the power vacuum circuit breaker according to the present invention.

Claims

A conductive component consisting comprised Cu phase Cu alloy mainly containing Cu or Cu, consisting Cu-Cr alloy containing 10 to 90 wt% Cu, which is constituted by the arc-proof component consisting of Cr In the manufacturing method of the contact material of the vacuum circuit breaker for electric power ,
First, the micro-Vickers hardness of the Cr particles in the Cu-Cr alloy when the Cu-Cr alloy is heated to 1030 ° C to 1080 ° C, which is just below the melting temperature of the Cu phase, and cooled to room temperature. Find the value Hr,
Next, Cr powder having a particle size of 0.1 to 150 μm and Cu powder having a particle size of 44 to 62 μm are mixed at a predetermined ratio and pressed at a predetermined value, and then sintered at a predetermined temperature, or a predetermined amount of the Cr Pressurize the powder at a predetermined value, sinter at 800 to 1400 ° C., infiltrate the Cu lump at 1100 to 1400 ° C., and cool at a predetermined speed to room temperature. When the Vickers hardness value is Hs,
One or more of the pressure during the pressurization, the temperature during the sintering, and the speed during the cooling are adjusted so that the [Hs / Hr] ratio is in the range of 1.0 to 1.6. The manufacturing method of the contact material of the vacuum circuit breaker for electric power.

A conductive component consisting comprised Cu phase Cu alloy mainly containing Cu or Cu, consisting Cu-Cr alloy containing 10 to 90 wt% Cu, which is constituted by the arc-proof component consisting of Cr In the manufacturing method of the contact material of the vacuum circuit breaker for electric power ,
First, when the Cu—Cr alloy is heated to 1030 ° C. to 1080 ° C., which is just below the melting temperature of the Cu phase, and cooled to room temperature, the micro Vickers hardness of the Cu phase in the Cu—Cr alloy is reduced. Find the value Ho,
Next, Cr powder having a particle size of 0.1 to 150 μm and Cu powder having a particle size of 44 to 62 μm are mixed at a predetermined ratio and pressed at a predetermined value, and then sintered at a predetermined temperature, or a predetermined amount of the Cr After pressing the powder at a predetermined value, sintering at 800 to 1400 ° C., infiltrating the Cu lump at 1100 to 1400 ° C., and then cooling to room temperature at a predetermined speed, the Cu phase micro in the Cu—Cr alloy When the Vickers hardness value is Hm,
One or more of the pressure during the pressurization, the temperature during the sintering, and the speed during the cooling are adjusted so that the [Hm / Ho] ratio is in the range of 1.0 to 2.0. The manufacturing method of the contact material of the vacuum circuit breaker for electric power.