Aq. acid bath for electrolytic coating of rhodium - contains rhodium ions e.g. in sulphate form, poly:carboxylic acid and orthophosphate gps. (BR 11.12.79)

摘要

Bath contains 0.1-30 (0.1-0.9)g/l Rh ions e.g. in sulphate form; 0.1-20 (0.1-5.0)g/l polycarboxylic acid contg. >=1 amino gp. e.g. glutamic acid; and 10-100 (40-60) g/l orthophosphate gps. The bath has a pH of 0.1-2.0 (0.5-1.5). The concn. of orthophosphate ion is pref. greater than that of sulphate ion in the bath. An electrolytic deposit of Rh on an article having at least one conducting surface can be obtd. by immersing the object in this aq. bath and passing a current between an insol. anode and the article. A bright electrolytic deposit of Rh can be obtd. using a coating bath with lower Rh content (typically 0.5 g/l) than that used (about 2 g/l) in conventional baths.