Rhodium Plating

the application of a thin layer (0.1–25 micrometers) of rhodium to the surface of metal articles in order to increase reflectivity, refractoriness, and resistance to corrosion, to ensure constant electrical conductivity upon contact, and to impart protective and decorative properties. The coating is applied by electroplating from sulfate (with additions of selenic acid), phosphate, aminochloride, and perchlorate electrolytes. The process is carried out with anodes made from thin sheets of metallic platinum or platinized titanium, and a water-soluble rhodium trichloride is used to prepare the electrolyte. Coatings up to 1 micrometer in thickness are applied, for example, to protect silver from tarnishing, to impart a decorative finish to articles, and to produce insoluble anodes. Thicker coatings are applied to ensure high chemical stability and resistance to wear.