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镀银使用的极板,除起电导体外,表面上还不断地发生溶解,以补偿镀液中银离子在阴极上的消耗,保持槽液成份的稳定。为使被镀零件得到高质量的镀层,最好选用99.99％的特号银作阳极。但由于特号银难于买到,而且价格昂贵,一般均采用99.95％的一号银压延板作阳极。一号银阳极板一般都要进行热处理,由于一号银中含有0.05％的金、铜、铁、锑、铋、碳和硫等杂质,其中铅、铜等重金属杂质,引起电镀过程中阳极氧化发黑,生成钝化膜。不仅降低了电镀电流效率,阻碍了阳极溶解,造成零件镀层厚度达不到技术要求;更严重的是伴随钝化膜剥落的同时,阳极微粒脱落进入镀液中,随着杂质的迁移,沉淀在被镀零件表面上,造成镀层粗糙,并有一颗颗明显的粒子。为解决电镀过程中银阳极氧化发黑问题,当提高镀银槽液
Silver plates used in the plate, in addition to the conductor from the outside, the surface still continue to dissolve in order to compensate for silver ion plating bath on the cathode consumption, to maintain the stability of bath components. In order to be plated parts get high-quality coating, it is best to use 99.99% of the special silver as the anode. However, because of the special silver is difficult to buy, but also expensive, generally using 99.95% of the first silver plate as the anode. Since the first silver plate contains 0.05% of gold, copper, iron, antimony, bismuth, carbon and sulfur impurities such as lead and copper, heavy metals such as lead and copper are caused to cause anodic oxidation in the electroplating process Black, generate passive film. Not only reduces the plating current efficiency, hinders the anode dissolution, resulting in parts coating thickness less than the technical requirements; more serious is accompanied by the exfoliation of the film at the same time, the anode particles fall into the bath, with the migration of impurities, precipitation Placed parts surface, resulting in rough coating, and a clear particles. In order to solve the blackening problem of silver anodizing in the electroplating process, when increasing the silver plating bath,