A PROCESS OF ELECTRO PLATINGCHROMIUM FROM AN AQUEOUS SOLUTION OF CHROMIUM(III)-THIOCYANATE COMPLEXES

摘要

pThe Cr concn. is 0.03M and is sufficiently weak to give a deposit whose colour is at least as bright as that of vapour deposited Cr. Bright Cr coatings can be formed (without the attendant problems of using Cr6+ baths) for decorative applications, and thick, coherent, smooth coatings can be formed for structural and mechanical applications. The ratio of the molar concns. of Cr/thiocyanate is pref. 1 : 2-4. The soln. pref. also contains an amino-acid (pref. aspartic acid) as buffer, in a molar concn. 1.25 times that of Cr. The bath temp. for a bright coating is pref. 40-60 degrees C, the brightest coloured coatings being formed using a current density 50 mA/cm2. The Cr concn. is pref. =0.02M. The pH of the bath is pref. 3.8 - 4.5./p[DE2944142A1]