Study On Chromium Plating With Pulse Current Electroplating Process

Aiming at the deficiencies of direct current chromium plating technology on 30CrMnSiA alloy steel, 1Cr11Ni2W2MoVA and 15-5PH(0Cr15Ni5Cu3Nb)stainless steel used on aeroseal components for undercarriage, this paper mainly studied the process of chromium plating with pulse current based on the standard bath.The process of pulse current electroplating have many parameters, set temperature at 60±1℃, quadrate pulse wave and 120 minutes for electroplating provisionally. According to the experience set the pulse process parameters with pulse frequency at 50-200 T/Min, duty cycle at 40-60%, current density at 40-80A/dm2. Ameliorated pulse process parameters with the orthogonal experiment, studied effect of pulse frequency, duty cycle and current density for the electrodeposited coating's appearance and properties. As a result current density is the most mainly factor affect appearance and property of the electroplating coating. The amounts of crack and porosity increased when current density raise, so did thickness and hardness, they turned thicker and stronger. It will improved photometric brightness, bonding strength, hardness and reduced emerge of the chromium-tumour, chromium-prick, the amounts of crack and porosity when the frequency and duty cycle on the properly range. We had best photometric brightness, hardness electroplating coating, chromium-tumout and chromium-prick was so slight, the amounts of crack and porosity get down to the valley bottom when the pulse frequency at 50 T/Min, duty cycle at 60%. Synthesize the data analysis of the orthogonal experiment and the result of coating's appearance and property tests, educed pulse process parameters after optimization as: current density at 40-60 A/dm2, pulse frequency at 50 T/Min, duty cycle at 60%.Aiming at the deficiencies of the electroplating temperature range on the orthogonal experiment, changed temperature for electroplating experiment on the base of optimization pulse process parameters, temperature parameters range as 50℃, 55℃, 60℃. Study the pulse electroplating coating's appearance and property with the direct current plating on the same current density, temperature and electroplating time. As a result pulse electroplating coating have great advantage to the direct current plating on the coating's appearance, brightness, smooth. No chromium-tumout or chromium-prick on the electroplating coating. No burning or miss-electroplating neither. Pulse electroplating coating have more powerful hardness and bonding strength than direct current plating, the amounts of crack and porosity are lower than direct current plating.In study with the different of coating's appearance and property on pulse electroplating coating or direct current plating in temperature-change experiment. Educed optimization pulse process parameters for 30CrMnSiA alloy steel, 1Cr11Ni2W2MoVA and 15-5PH(0Cr15Ni5Cu3Nb)stainless steel. As follows: with standard electroplating bath, current density at 50-70 A/dm2, pulse frequency at 50 T/Min, duty cycle at 60%, temperature at 55-60℃, electroplating time is madding for need. This pulse process parameters is the same with these three materials hereinbefore with good stability, and beautiful appearance, excellent properties for use.