汽车冷轧钢板化学镀Ni-W-P合金镀层的耐蚀性能研究

以提高汽车冷轧钢板的耐蚀性能为目的开展研究。在冷轧钢板表面制备了化学镀Ni-WP合金镀层,研究了镀液组成和工艺参数对镀层耐蚀性能的影响。结果表明,在镀液组成为30 g/L硫酸镍、20 g/L次亚磷酸钠、40 g/L钨酸钠、60 g/L柠檬酸钠、12 g/L乳酸以及20 g/L硫酸铵,工艺参数为施镀温度88℃、镀液pH值8.5的条件下,所得镀层(优化后镀层)的腐蚀速率最小,约为0.035 mg/(cm^2·h),是冷轧钢板腐蚀速率的1/3,腐蚀电位相比冷轧钢板正移约300 mV,腐蚀电流密度降低了一个数量级。优化后镀层相对于冷轧钢板属于阴极性镀层,能有效提高冷轧钢板的耐蚀性能。

Corrosion Resistance Research of Electroless Ni-W-P Alloy Coatings Prepared on Automobile Cold-Roll Steel Plate

The research was conducted aiming to improve the corrosion resistance of automobile coldroll steel plate. Electroless Ni-W-P alloy coatings were prepared on cold-roll steel plate and the influences of plating bath composition and process parameters on the corrosion resistance of the coatings were studied. The results showed that the optimal plating bath composition and process parameters were determined as follows:nickel sulfate 30 g/L,sodium hypophosphite 20 g/L,sodium tungstate 40 g/L,sodium citrate 60 g/L,lactic acid 12 g/L,ammonium sulfate 20 g/L,plating temperature 88 ℃ and plating bath pH value 8.5. Corrosion rate of the coatings prepared under the optimal conditions was about 0.035 mg/(cm^2·h)(minimum value),which was about one third of that of cold-roll steel plat. Compared with coldroll steel plate,the corrosion potential of the optimized coatings moved to the positive direction by 300 mV,and the corrosion current density decreased by an order of magnitude. The optimized coating belongs to cathodic coating in comparison with cold-roll steel plate,and it can effectively improve the corrosion resistance of cold-roll steel plate.