【発明の詳細な説明】[Detailed description of the invention]
本発明は電気接点材料、特に、耐溶着性に優れ
無害な電気接点用焼結材料に関する。
従来、中負荷領域の電気接点材料として汎用さ
れているAgCdO系焼結材料は、優れた接点性能
を有しているが、有害なCdを原料とするためそ
の製造工程および使用中にCdを含有する粉塵と
なつて公害を発生する恐れがあり、しかもAg含
有量が多い為コストが高いという欠点もあつた。
他方、Cdを含有しない無害な電気接点材料とし
てAgNi系焼結材料が実用化されているが、この
AgNi系焼結材料はAgCdO系のものに比べ耐溶着
性において劣るという問題があつた。
本発明は、従来のAgNi系焼結材料の欠点であ
る耐溶着性を向上させると共に、AgCdO系電気
接点材料と同等以上の接点性能を有する安価な電
気接点材料を提供することを目的とするものであ
る。
本発明の要旨は、Ni10〜30％、In1.7〜５％、
残部実質的にAgおよび不可避的不純物からなる
電気接点用焼結材料にある。
本発明に係る電気接点用焼結材料の成分組成を
前記のように限定した理由について説明すると、
Niは耐消耗性を向上させるために添加されるが、
Niが10％未満ではその効果が得られず、また30
％を越えると接触抵抗が増大するので、10〜30％
とした。また、Inは接触抵抗を安定させ、かつア
ークを減少させるために添加されるもので、その
添加量が1.7％未満ではその添加効果が十分に達
成されず、５％を越えると接触抵抗が増大し耐溶
着性が悪くなるので1.7〜５％とした。
前記成分組成の本発明に係る電気接点用焼結材
料は、従来のAgNi系焼結材料に比べ耐溶着性が
大幅に改善され、AgCdO系焼結材料とほぼ同等
の耐溶着性を示す。また、接触抵抗および耐消耗
性に関しては、AgNi系のものとほぼ同等であ
り、AgCdO系のものに比べて若干劣るが実用上
問題となる程度の差ではない。しかも、本発明に
係る電気接点用焼結材料は、AgCdO系焼結材料
に比べAg含有量を低減できるので安価に製造す
ることができ、有害なCdを含有しないので公害
発生の原因となることがない。
前記電気接点用焼結材料は、原料としてAg，
NiおよびInの各微粉末を用い、これらを所定比
で配合し、加圧成形後、不活性ガス雰囲気中700
〜800℃で１〜20時間焼結する方法により製造さ
れる。なお、一般に、InなどがAg中に固溶する
と、純Agに比べて若干抵抗が増大するが、電気
接点材料として特に問題となることはない。ま
た、焼結後、得られた焼結体にサイジング、コイ
ニングなどの再加工を施すのが好ましい。
原料粉末としては、通常、0.1〜103μ、好まし
くは0.5〜20μのものが使用できるが、これらは市
販のものをそのまま使用すればよい。
以下、本発明の実施例について説明する。
実施例
原料粉末をAg粉末（平均粒径：1.08μ）70重量
％、Ni粉末（平均粒径：2.2μ）25重量％、In粉末
（平均粒径：5μ）５重量％の割合で配合してボー
ルミルにて均一に混合し、その混合粉末を4t／cm2
の圧力下で直径20mm、長さ30mmに成形し、得られ
た成形体に不活性ガス雰囲気中750℃で２時間加
熱して焼結させ電気接点用焼結体を得た。この焼
結体を700〜800℃に加熱し、押出機を用いて直径
６mmの棒状体に成形した後、伸線ヘツダーにて加
工して得た接点をリレーに組み込み、試供品とし
た。
比較例 １
原料としてAgとCdOとの粉末を用い、実施例
と同様にしてAg−12％CdOからなる焼結体を得
て接点となし、これをリレーに組み込み試供品と
した。
比較例 ２
原料として実施例で用いたAgおよびNiの粉末
を用い、これらをAg70％、Ni30％の重量比で混
合し、実施例と同様にしてAgNi系焼結体を得て
接点となし、これをリレーに組み込み供試品とし
た。
前記実施例および比較例で得たリレーについ
て、下記の条件で接触抵抗、耐消耗性および溶着
特性を測定した。それらの結果を表に示す。な
お、耐消耗性については35万回開閉動作させた
時、接点の接触力が５ｇ以下になつたリレーの個
数で表わしてある。
［試験条件］
試供品：リレー（2C）各５個
電圧：AC100V
電流：7A
負荷：抵抗負荷
接触力：初期20〜30ｇ
開閉頻度：30回／分
The present invention relates to an electrical contact material, and in particular to a harmless sintered material for electrical contacts that has excellent welding resistance. Conventionally, AgCdO-based sintered materials, which have been widely used as electrical contact materials in the medium load range, have excellent contact performance, but because they are made from harmful Cd, they contain Cd during the manufacturing process and during use. There is a risk that it will turn into dust and cause pollution, and it also has the disadvantage of being expensive due to the high Ag content.
On the other hand, AgNi-based sintered materials have been put into practical use as harmless electrical contact materials that do not contain Cd.
AgNi-based sintered materials have a problem in that they have inferior adhesion resistance compared to AgCdO-based materials. The purpose of the present invention is to improve the welding resistance, which is a drawback of conventional AgNi-based sintered materials, and to provide an inexpensive electrical contact material that has contact performance equivalent to or better than that of AgCdO-based electrical contact materials. It is. The gist of the present invention is that Ni10-30%, In1.7-5%,
The remainder consists of a sintered material for electrical contacts consisting essentially of Ag and unavoidable impurities. The reason why the composition of the sintered material for electrical contacts according to the present invention is limited as described above is as follows.
Ni is added to improve wear resistance, but
If Ni is less than 10%, this effect cannot be obtained, and if Ni is less than 10%,
If it exceeds 10% to 30%, the contact resistance will increase.
And so. In addition, In is added to stabilize the contact resistance and reduce arcing, and if the amount added is less than 1.7%, the added effect will not be fully achieved, and if it exceeds 5%, the contact resistance will increase. However, since the welding resistance deteriorates, the content was set at 1.7 to 5%. The sintered material for electrical contacts according to the present invention having the above-mentioned composition has greatly improved adhesion resistance compared to conventional AgNi-based sintered materials, and exhibits adhesion resistance almost equivalent to that of AgCdO-based sintered materials. In addition, in terms of contact resistance and wear resistance, they are almost the same as those of AgNi-based materials, and are slightly inferior to AgCdO-based materials, but the difference is not to the extent that it poses a practical problem. Furthermore, the sintered material for electrical contacts according to the present invention can be manufactured at a lower cost because it has a lower Ag content than AgCdO-based sintered materials, and does not contain harmful Cd, which can cause pollution. There is no. The sintered material for electrical contacts uses Ag,
Using fine powders of Ni and In, these were mixed in a predetermined ratio, and after pressure molding, 700°C in an inert gas atmosphere
Manufactured by sintering at ~800°C for 1 to 20 hours. Generally, when In or the like is dissolved in Ag, the resistance increases slightly compared to pure Ag, but this does not pose any particular problem as an electrical contact material. Moreover, after sintering, it is preferable to subject the obtained sintered body to reprocessing such as sizing and coining. As the raw material powder, powders of 0.1 to 10 3 μm, preferably 0.5 to 20 μm can be used, and commercially available powders may be used as they are. Examples of the present invention will be described below. Example Raw material powders were blended at a ratio of 70% by weight of Ag powder (average particle size: 1.08μ), 25% by weight of Ni powder (average particle size: 2.2μ), and 5% by weight of In powder (average particle size: 5μ). The mixed powder was mixed uniformly in a ball mill at 4t/ cm2.
The resulting molded body was heated and sintered at 750° C. for 2 hours in an inert gas atmosphere to obtain a sintered body for electrical contacts. This sintered body was heated to 700 to 800°C, formed into a rod-shaped body with a diameter of 6 mm using an extruder, and then processed using a wire drawing header.The resulting contacts were assembled into a relay and used as a sample. Comparative Example 1 Using powders of Ag and CdO as raw materials, a sintered body of Ag-12% CdO was obtained in the same manner as in the example and used as a contact, and this was incorporated into a relay to make a sample. Comparative Example 2 Using the Ag and Ni powders used in the examples as raw materials, they were mixed at a weight ratio of 70% Ag and 30% Ni, and in the same manner as in the examples, an AgNi-based sintered body was obtained and used as a contact, This was assembled into a relay and used as a sample. Contact resistance, wear resistance, and welding characteristics of the relays obtained in the Examples and Comparative Examples were measured under the following conditions. The results are shown in the table. In addition, wear resistance is expressed as the number of relays whose contact force was 5 g or less after 350,000 opening and closing operations. [Test conditions] Sample: 5 relays (2C) each Voltage: AC100V Current: 7A Load: Resistive load Contact force: Initial 20-30g Opening/closing frequency: 30 times/min
【表】
表１に示す結果から明らかなように、本発明に
係る電気接点材料は、比較例２のものに比べ耐溶
着性が大幅に改善され、比較例１のものと同等の
特性を示している。また、接触抵抗や耐消耗性に
ついては、比較例１のものに比べてわずかに劣る
ものの、実用上あまり問題とならない程度の差で
あることがわかる。[Table] As is clear from the results shown in Table 1, the electrical contact material according to the present invention has significantly improved adhesion resistance compared to that of Comparative Example 2, and exhibits the same characteristics as that of Comparative Example 1. ing. In addition, it can be seen that although the contact resistance and wear resistance are slightly inferior to those of Comparative Example 1, the differences are such that they do not pose much of a problem in practice.