Study on Improvement of Mechanical Properties after Heat Treatment of Hard Chromium Electrodeposits with Additives

The addition of cyclo propane carbonyl (cpc) to chromium electroplating bath resulted in a chromium deposit which had greatly improved mechanical properties compared to conventional chromium deposits in condition of heat treatment at high temperature. The as-deposited layers had a Vicker`s hardness of about 1170, which is comparable to that of conventional chromium plating deposits. With annealing, the hardness goes through a maximum of 1650 at . Generally speaking, the hardness of conventional plating decreases monotonically with heat treatment. X-ray diffraction show that annealing up to above causes formation and growth of chromium crystallites and that chromium carbides form at above temperature.