Coloring mechanism and new coloring technic of Cu alloys

研究了在含有硫酸铜和人工孔雀石的溶液中形成的铜合金着色层的着色机理、微观结构和腐蚀效应。这种上色技术被用于日本传统的金属工艺。对高贵的着色技术也进行了研究。铜合金着色层的基本结构是晶态和非晶态Cu20的混合态，认为非晶态Cu20是由S和氯从溶液中扩散到合金表面形成的。对于Shakudou，Cu-4%Au合金，Au非常细小的晶体分布在Cu20基体层中，平均直径为5 nm。对于黄铜，铜-30%锌合金，观察到锌物种优先在溶液中溶解。因此，氧化层Cu20中的锌含量很低。对于鲜市铜-25%银合金，铜的物种易被氧化，并引入晶态和非晶态的Cu20。然而，银物种变成了细小的金属颗粒。部分残留的Ag物种分布在Cu2O层中，形成Ag2S。入射光主要被分布在Cu2O层和Cu2O层中的金属微晶吸收，基质金属反射入射光。上色是由于这些复合现象造成的。通过着色处理，电流-电压特性阈值向高压侧移动。这意味着着色层的形成增加了耐腐蚀性。通过热氧化等手段获得了开发新着色工艺的一些基础数据。

Coloring mechanism, fine structure, and corrosion effect of coloring layers of copper alloys formed in a solution containing copper sulphate and artificial malachite have been investigated. This coloring technic is used in a traditional Japanese metal-craft. Noble coloring technic has also been investigated. The basic structure of coloring layer of Cu alloys is a mixed state of crystalline and amorphous Cu_20. It is thought that the amorphous Cu_20 is formed by diffusion of S and Cl from the solution to the alloy surface. For shakudou, Cu-4%Au alloy, Au very fine crystals distribute in the Cu_20 matrix layer and the average diameter is 5 nm. For brass, Cu-30%Zn alloy, it is observed that Zn species dissolves preferentially in the solution. Therefore, Zn concentration in the oxide layer Cu_20 is very low. For shibuichi, Cu-25% Ag alloy, Cu species is oxidized easily and the crystalline and amorphous Cu_20 are introduced. However, Ag species becomes fine metal particles. A part of residual Ag species distributed in Cu_2O layer makes Ag_2S. The incident light is absorbed mainly by metal fine crystals distributed in the Cu_2O layer and the Cu_2O layer, and the matrix metal reflects the light. Coloring is due to these composite phenomena. The threshold of currnet-voltage characteristic shifts to the direction of the high voltage side by coloring treatment. This means that the corrosion resistance increases by the coloring layer formation. Some basic data to develop new coloring technic are obtained by thermal oxidation and others.