CHROMIUM DEPOSITION FROM DILUTED SULFATE-SOLUTIONS

A sulfate solution with a low content of Cr(III) is developed for obta ining plastic chromium coatings at a current efficiency of 30-35%. The solution allows one to obtain thick (>100 mu m) coatings without crac ks, possesses a high throwing power, and permits a high-volume current density. The proposed composition of the solution (g/l) and operating conditions are as follows: Cr-2(SO4)(3) . 6H(2)O-25; Na2SO4-100; H3BO 3-35-40; malonic or oxalic acid-7-10; sulfur-containing surface-active agent 0.08-0.10; pH 2.2-4.2; and current density-2-6 A/dm(2).