微量铟和锡对银合金抗变色及耐烧损性能的影响

Effect of Trace Indium and Tin on Anti-tarnishing and Buring Resistance of Silver Alloy

针对饰品用斯特林银合金易发生硫化及氧化等变色现象,研究了添加微量In、Sn后合金的耐烧损、抗变色等性能。结果表明,添加0.375%的In代替Cu,可增加银合金的抗硫化变色和抗汗液腐蚀能力,但当In含量较低时反而会对抗汗液腐蚀能力造成不利影响;Sn元素对银合金的抗变色性能影响并不明显;补口合金中添加的In与Sn对925银合金中Zn的耐烧损性能影响规律及机理较为复杂;熔化次数较少、时间较短时In效果优于Sn,但Sn对Zn的保护时间较长;In与Sn含量降至一定程度都会加速Zn的烧损,而Zn对提高银合金抗变色能力上有着重要作用。可根据银合金需要重熔次数、熔化时间、服役环境来确定银合金中添加In、Sn、Zn的含量,达到所需效果。

The anti-tarnish and burning resistance properties of 925Ag alloy are investigated by manipulating trace indium and tin contents, makes progress in solving the problem of 925Ag alloy tarnishing caused by sulphurization and oxidation. The results indicates that 0.375 wt% of In enhances the anti-sulphurization and anti-perspiration properties while extremely low content of In affectes those two properties adversely, and the effects of solely addition of Sn on those two properties are not obvious. Trace In and Sn＆#39;s mechanisms and effects of protecting Zn within the 925Ag alloy is intricate. When melting time is short, In protects Zn more effectively than Sn, though Sn prolongs the protection time for Zn. When the content of In and Sn drop to a certain level, burning of Zn will be accelerated. Zn plays an important role in improving the anti-discoloration of silver alloy, so the content of In, Sn, Zn were determined according to re-melting times, melting duration time and service environment of the silver alloy to achieve the desired results.