ABSTRACT

A stripping solution with ferric ions and hydrogen peroxide oxidants, and sodium chloride complex agent is suggested for use with 18 K yellow and red gold alloys. After stripping for 5 min, stripping properties such as passivation layer elimination, weight loss, microstructure, Lab colour index, and elemental content change were analysed. The stripping process led to the usual passivation layer of metal sulphides being eliminated. Weight loss occurred in the alloy during the initial 1 min of stripping, and after this the weight loss slowed down. Stripping rate was similar to the traditional cyanide process. Microstructure examination showed the passivation layer’s uneven surface was removed and the alloy’s lustre was enhanced after 3 min stripping. However, the lustre was decreased after 5 min stripping due to excessive surface etching. For red colour, the colour became yellowish as stripping time increased by formation of a 0.6 μm-thick Au-rich zone. The results suggest that the proposed halide stripping could replace the conventional cyanide process.

摘要

建议将含铁离子和过氧化氢氧化剂以及氯化钠络合剂的剥离溶液用于18 K黄金和红金合金。剥离5分钟后，分析剥离性能，例如钝化层消除，重量损失，微观结构，实验室色指数和元素含量变化。汽提过程导致消除了通常的金属硫化物钝化层。在剥离的最初1分钟内，合金发生了重量损失，此后重量损失减慢了。汽提速率类似于传统的氰化物工艺。显微组织检查表明，剥离3分钟后，钝化层的不平整表面被去除，合金的光泽得到增强。但是，剥离5分钟后，由于过度的表面蚀刻，光泽降低了。对于红色，由于形成0.6μm厚的富金区，剥离时间增加，颜色变为淡黄色。结果表明，所提出的卤化物汽提可以代替常规的氰化物工艺。