Application Study For Chrome Plating On Ring Grooves Surface Of Piston Crown

Under the condition of high temperature, high pressure, corrosion and friction, working life of piston crown (which used for low speed marine diesel engine) ring groove will be influenced easily. Chrome plating technique can plate a chrome layer with high hardness on the groove surface rapidly and it will improve resistance character of groove surface. Hence, this technique is used widely in the piston crown ring groove treatment.In the aspects of manufacturing and reconditioning of piston crown, rotating chrome plating is operating in DMI (Dalian) for the treatment ring groove surface. Quality problem sometime happened during the production. The reason was located in the aspects of metal impurities. Dirt of old piston crown was brought to the plating solution in process of reconditioning. The metal impurities circulated to the plating solution for the new piston crown. Plating porosity was found on the chrome layer and re-plating needs to be carried.I used the Cr6+-plating technique with Constant Potentiometer to select the Chromium plating solution from four solutions with best-quality by comparing their plating layer. Then made the single factor experiment to detect the contents of each factor for best-quality solution, the result is:CrO3:220-270g/L, H2SO4:1.92g/L, CrO3/H2SO4=130:1. Detected the contents of the impurities which have bad affects to the plating solution and the plating layer with regard to the best-quality solution, therefore the contents of the impurities can be monitored, malfunction of the plating can be avoided in production. The contents of these impurities should be maintained in the range as following: Independent plating circulation of plating solution was carried in DMI (Dalian) now. We modified the plating device and intensive attention was paid to impurities. The productivity was improved and quality problem decreased.