Abstract
Bath composition and plating conditions of black chromium plating bath containing hydrogen silicofluoride were given in the previous report (Part 1). The addition of hydrogen silicofluoride to this bath was intended to give higher blackness and evenness in coloration but these effects were not com- plete in the results.
Then, effects of further addition agents to the above bath were studied and found that the addition of nitric and formic ions among acid radicals and barium ion among metallic ions was most effective for color in platings; and no other agents were effective.
Bath composition and plating conditions for giving the most even and black coloration were as follows:
Cr2O3……300g/l
H2SiF6……1g/l
Addition agents……3-5g/l
Bath temperature……above 10°C
Dk……30-50amp./dm2
