【発明の詳細な説明】[Detailed description of the invention]
本発明は、指輪、ネツクレス、ブローチ、ネク
タイピン、カフスボタン、時計枠、時計バンド、
ライター、筆記具、眼鏡枠、イヤリング等の材料
として使用する白金合金の改良に関するものであ
る。
従来、上述の如き装飾品の材料としては白金−
パラジウム（５〜15重量％）合金が多用され、そ
の他白金−パラジウム−銅合金が使用されてい
る。然し乍ら前者の白金−パラジウム（５〜15重
量％）合金は加工性、耐汗性、耐変性、鋳造性に
優れているが、機械的強さ特に硬さが低い為研摩
中にすり傷、押傷が付き易く且つ光沢出にくく、
また完成品として使用している場合も傷が付き易
く、また宝石付指輪の場合、宝石を止めている部
分がゆるんで宝石が脱落するという欠点があつ
た。
また後者の白金−パラジウム−銅合金は、前記
白金−パラジウム合金と同様加工性に優れ、その
上機械的強さに幾分優れていて白金−パラジウム
合金の改良品が、鋳造時に鋳型と反応する為、細
かい模様が現れず、不鮮明になり、しかも酸素濃
度を抑制できない為鋳巣が生じたり、大気焼鈍後
に変色したりするという欠点があつた。
本発明は上記欠点を解消せんが為になされたも
のであり、耐汗性、耐変色性、加工性は勿論のこ
と機械的強さ、鋳造性などに優れた装飾品用白金
合金を提供せんとするものである。
本発明による装飾品用白金合金は、白金85〜94
重量％、パラジウム５〜11重量％、コバルト0.08
〜0.7重量％及びジルコニウム、チタン、タング
ステンの少なくとも１種総量で1.5〜４重量％よ
り成るものである。
本発明による装飾品用白金合金に於いて、コバ
ルトを添加した理由は、装飾品用材料としての加
工性を損なわないこと、鋳造時に鋳型と反応しな
いこと及び鋳造時に酸素濃度を抑制できることの
条件を満たし、機械的強さ及び鋳造性を向上させ
る為であり、その添加量を0.08〜0.7重量％とし
たのは、0.08重量％未満では機械的強さ及び鋳造
性の向上がほとんど見られず低い0.7重量％を超
えると大気中で焼鈍した場合、変色したり、耐汗
性が低下するおそれがあるからである。
またジルコニウム、チタン、タングステンの少
なくとも１種を添加したのは、これらの諸元素は
白金やパラジウムと金属間化合物を作り、耐汗性
を阻害せず硬化して一層機械的強さを向上させる
為であり、その添加量が1.5重量％未満では機械
的強さがやや弱い。また４重量％を超えると加工
性がやや悪くなるからである。
また、本発明の装飾品用白金合金に於けるパラ
ジウム含有量は、機械的強さ、価格、耐蝕性、鋳
造性等の点から５〜11重量％が好ましい。
以下本発明による装飾品用白金合金の効果を明
瞭ならしめる為に実施例及び従来例について述べ
る。
下表の左欄に示す成分組成の実施例No.１〜９の
装飾品用白金合金と従来例のNo.10、No.11の装飾品
用白金合金の硬さ、鋳型の細かい模様の再現度、
巣の発生度合い、大気焼鈍後の変色度合、及び耐
汗性について、夫々大気中900℃で１時間焼なま
し後測定したところ、下表の右欄に示すような結
果を得た。
The present invention includes rings, necklaces, brooches, tie pins, cufflinks, watch frames, watch bands,
This invention relates to the improvement of platinum alloys used as materials for lighters, writing utensils, eyeglass frames, earrings, etc. Conventionally, platinum has been used as a material for decorative items such as those mentioned above.
Palladium (5 to 15% by weight) alloys are often used, and platinum-palladium-copper alloys are also used. However, although the former platinum-palladium (5 to 15% by weight) alloy has excellent workability, sweat resistance, deterioration resistance, and castability, it has low mechanical strength, especially hardness, and is prone to scratches and pressure during polishing. Easily scratched and hard to shine,
Furthermore, when used as a finished product, it is easily scratched, and in the case of rings with jewels, the part that holds the jewels loosens, causing the jewels to fall off. In addition, the latter platinum-palladium-copper alloy has excellent workability similar to the platinum-palladium alloy described above, and also has somewhat superior mechanical strength, and improved platinum-palladium alloys react with the mold during casting. As a result, fine patterns do not appear and become unclear, and furthermore, since the oxygen concentration cannot be suppressed, cavities occur and discoloration occurs after atmospheric annealing. The present invention was made in order to eliminate the above-mentioned drawbacks, and provides a platinum alloy for ornaments that is excellent in sweat resistance, discoloration resistance, workability, mechanical strength, castability, etc. That is. The platinum alloy for ornaments according to the present invention has platinum 85 to 94
wt%, palladium 5-11 wt%, cobalt 0.08
~0.7% by weight, and the total amount of at least one of zirconium, titanium, and tungsten is 1.5 to 4% by weight. The reason why cobalt is added to the platinum alloy for ornaments according to the present invention is to satisfy the following conditions: it does not impair workability as a material for ornaments, it does not react with the mold during casting, and it suppresses oxygen concentration during casting. This is to improve mechanical strength and castability, and the reason why the amount added is 0.08 to 0.7% by weight is that if it is less than 0.08% by weight, there will be little improvement in mechanical strength and castability, which is low. This is because if the content exceeds 0.7% by weight, there is a risk of discoloration or decreased sweat resistance when annealing is performed in the air. In addition, at least one of zirconium, titanium, and tungsten was added because these elements form intermetallic compounds with platinum and palladium, harden without impairing sweat resistance, and further improve mechanical strength. If the amount added is less than 1.5% by weight, the mechanical strength is somewhat weak. Moreover, if the content exceeds 4% by weight, processability will deteriorate somewhat. Further, the palladium content in the platinum alloy for ornaments of the present invention is preferably 5 to 11% by weight from the viewpoints of mechanical strength, cost, corrosion resistance, castability, etc. Examples and conventional examples will be described below in order to clarify the effects of the platinum alloy for ornaments according to the present invention. Reproduction of the hardness and fine pattern of the mold of the platinum alloys for ornaments of Example Nos. 1 to 9 and the platinum alloys for ornaments of conventional examples No. 10 and No. 11 with the composition shown in the left column of the table below. Every time,
The degree of formation of cavities, the degree of discoloration after atmospheric annealing, and the sweat resistance were each measured after annealing at 900°C in the atmosphere for 1 hour, and the results shown in the right column of the table below were obtained.
【表】
なお人工汗の試験はNH4Cl15.5ｇ／、
NaCl20ｇ／、醋酸2.5ｇ／、尿素５ｇ／、
乳酸15ｇ／、PH4.7の液組成で液温40℃、240時
間浸漬後判定した。
上記表で明らかなように本発明による装飾品用
白金合金は、従来の装飾品用白金合金に比し焼な
まし後の硬さが優れ、鋳造した際の鋳型の細かい
模様の再現度合や鋳巣の発生度も極めて優れてい
ることが判る。また耐汗性や耐変色性もついても
従来の白金−パラジウム合金と何等そん色がない
ことが判る。
以上詳記した通り本発明の装飾品用白金合金
は、従来の装飾品用白金合金の特性を害すること
なく、さらに加工性、機械強さ、鋳造性を向上さ
せているので、従来の装飾品用白金合金にとつて
代わることのできる画期的なものと言える。[Table] The artificial sweat test was conducted using NH 4 Cl15.5g/,
NaCl 20g/, acetic acid 2.5g/, urea 5g/,
Judgment was made after immersion for 240 hours at a liquid temperature of 40°C with a liquid composition of lactic acid 15g/PH4.7. As is clear from the table above, the platinum alloy for ornaments according to the present invention has superior hardness after annealing compared to conventional platinum alloys for ornaments, and has excellent reproduction of fine patterns in molds when cast. It can be seen that the incidence of nest formation is also extremely high. It can also be seen that even in terms of sweat resistance and discoloration resistance, it is no different from conventional platinum-palladium alloys. As detailed above, the platinum alloy for ornaments of the present invention has improved workability, mechanical strength, and castability without impairing the properties of conventional platinum alloys for ornaments. It can be said to be an epoch-making product that can replace platinum alloys.