Abstract
The paper reports work on the study of the effects of temperature, current density and time on thickness of nickel, copper and hard chromium coatings produced by a multiple electroplating process. Within the ranges of the experimental temperature and current density for all of the nickel, copper and chromium electroplatings, a maximum in the coating thickness as a function of temperature or current density exists. The optimized plating conditions to obtain the thickest coatings are at 2.5 A/dm 2 and 49 °C for nickel, 0.8 A/dm 2 and 20 °C for hydroxyl ethydene diphosphate (HEDP) copper, 2.6 A/dm 2 and 30 °C for acid copper and 29 A/dm 2 and 54 °C for hard chromium. Under the optimized conditions, a sound adhesion between any plated materials over the aluminum base is achieved, and a bright, uniform and flawless chromium coating is obtained with a microhardness of HV1029. The hard chromium coating layer has a higher anti-pitting property in 3.5 wt.% sodium chloride solution than that of a 0.1% C–13% Cr stainless steel.
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