【発明の詳細な説明】[Detailed description of the invention]
（産業上の利用分野）
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、筆記用具、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。
（従来技術とその問題点）
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、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が出にくく、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
上機械的強さにも優れているが、鋳造時に鋳型と
反応する為、細かい模様が現われず、不鮮明にな
り、しかも酸素濃度を抑制できないため鋳巣が生
じるという欠点があつた。
（発明の目的）
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、加工性は勿論のこと機械的強さ、鋳造
性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。
（発明の構成）
本発明による装飾品用白金合金は、白金84〜96
重量％、クロム１〜10重量％、マンガン１〜15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、クロ
ムを添加した理由は、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１〜10重量％としたのは１
重量％未満では機械的強さ及び鋳造性の向上が低
く、10重量％を超えると加工性が著しく低下する
からである。
またマンガンは白金と金属間化合物を作り、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重量％未満では機械的強さの改善が
殆んどなく、15重量％を超えると加工性が悪くな
るからである。
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。
（実施例及び従来例）
下表の左欄に示す成分組成の実施例１〜６の装
飾品用白金合金と比較例１，２及び従来例１〜６
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、及び、加工性につい
て、夫々焼なまし後に測定したところ、下表の右
欄に示すような結果を得た。
(Industrial Application Field) The present invention is applicable to 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. (Prior art and its problems) Conventionally, platinum has been used as a material for decorative items such as those mentioned above.
Palladium (5-15% by weight) alloys are often used, and platinum-palladium-copper alloys are also used. However, although the former platinum-palladium (5-15% by weight) alloy has excellent workability and castability, its mechanical strength and especially its hardness are low, so it is easily scratched and stamped during polishing, and its luster is poor. They are difficult to remove and are easily scratched when used as a finished product, and rings with jewels have the disadvantage that the part that holds the jewels loosens and the jewels fall off. The latter platinum-palladium-copper alloy has excellent workability and mechanical strength like the platinum-palladium alloy, but because it reacts with the mold during casting, fine patterns do not appear. The problem was that it became unclear and that cavities were formed because the oxygen concentration could not be suppressed. (Object of the Invention) The present invention was made in order to eliminate the above-mentioned drawbacks, and aims to provide a platinum alloy for ornaments that is excellent in not only workability but also mechanical strength and castability. be. (Structure of the Invention) The platinum alloy for ornaments according to the present invention has platinum 84 to 96
% by weight, 1 to 10% by weight of chromium, and 1 to 15% by weight of manganese. The reason why chromium is added to the platinum alloy for ornaments according to the present invention is that it satisfies the conditions of not reacting with the mold during casting, suppressing oxygen concentration during casting, and improving mechanical strength and castability. Therefore, the amount added was set at 1 to 10% by weight.
This is because if it is less than 10% by weight, improvements in mechanical strength and castability will be low, and if it exceeds 10% by weight, workability will be significantly reduced. In addition, manganese forms an intermetallic compound with platinum and hardens to further improve mechanical strength. If the amount added is less than 1% by weight, there is almost no improvement in mechanical strength, and 15% by weight This is because if it exceeds this, workability will deteriorate. 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. (Examples and Conventional Examples) Platinum alloys for ornaments of Examples 1 to 6, Comparative Examples 1 and 2, and Conventional Examples 1 to 6 having the component compositions shown in the left column of the table below.
The hardness of the platinum alloy for ornaments, the reproduction of fine patterns in the mold, the degree of occurrence of cavities, and the workability were measured after annealing, and the results shown in the right column of the table below were obtained. Ta.
【表】
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
模様の再現度合も極めて優れていることが判る。
（発明の効果）
以上詳記した通り本発明の装飾品用白金合金
は、加工性、機械的強さ、鋳造性が極めて優れて
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] As is clear from the above table, the platinum alloy for ornaments according to the present invention has superior hardness after annealing compared to conventional platinum alloys for ornaments, and reproduces the fine patterns of the mold when cast. It can be seen that the quality is also extremely good. (Effects of the Invention) As detailed above, the platinum alloy for ornaments of the present invention has extremely excellent workability, mechanical strength, and castability, so it can be used as a substitute for conventional platinum alloys for ornaments. It can be said to be a revolutionary thing.