METHOD OF PRODUCING CHROMIUM COATINGS HARDENED BY HEATING Russian patent published in 2000 - IPC

FIELD: production of carbon-containing chromium coatings by electrochemical methods. SUBSTANCE: method involves production of carbon-containing chromium coatings whose hardness rises after their heat treatment. For deposition of coatings electrolytes are used at temperature less than 15 C with the following weight ratios of components: sulfuric acid-chromic anhydride from 1:50 to 1:20; trivalent chromium-chromic anhydride from 1:40 to 1: 12; formic acid-trivalent chromium at least 3:1; and formic acid-chromic anhydride not more 1: 2. Raw deposits are subjected to heat treatment at temperature not more than 500 C. The invention ensures increased stability of bath operation, increased current efficiency up to 50-60% and microhardness of coatings up to 2000 kg/sq.mm. EFFECT: higher efficiency. 3 ex