Exploration of the Feasibility to Conduct High-Speed Chromium Electrodeposition in Trivalent Chromium Sulfate Solution

With a view to the replacement of hexavalent chromium plating by trivalenl chromium plating as a clean technology,the effects of current density,plating time,and type of substrate materials on the plating rate of high-speed trivalent chromium electroplating in a sulfate bath were investigated.Results show that compact and amorphous Cr coating can be prepared on Cu,Ni,and mild car-bon steel substrates by high-speed trivalent chromium electropla-ting in sulfate bath,and the plating rate on copper is much higher than that on mild steel and nickel.Namely,the average plating rate on Cu substrate at a current density of 10 A/dm is as much as 2.50 μm/min,and the thickness of the Cr coating after plating for 10 s is as much as 0.40 μm.However,the plating rate on mild steel and nickel is only 0.50 μm/min,and the resulting Cr coating plated under the same conditions is only about 0.10 μm thick.Moreover,the current efficiency of trivalent chromium plating is closely related to electric current density,and it is as high as over 25.0% on copper substrate at a current density of 10～12 A/dm2.