采用三价铬硫酸盐体系在普通碳素钢基体上电镀Fe-Ni-Cr合金镀层,通过浸泡失重法研究不同工艺条件下制备的镀层在3.5%NaCl溶液中的耐蚀性能,并用电化学分析方法研究了镀层试样的耐蚀机理.结果表明,最佳电镀Fe-Ni-Cr合金工艺为:主盐浓度FeSO_4·7H_2O 15 g/L、NiSO_4·6H_2O 8 g/L、Cr(SO_4)_3·6H_2O 200g/L;络合剂柠檬酸浓度70 g/L;电流密度为4 A/dm~2,电镀温度为55℃.该工艺制备的Fe-Ni-Cr合金镀层在3.5%NaCl溶液中的腐蚀速率为73.2 mg·m.h,耐蚀性比基体提高23.3%.
The Fe-Ni-Cr alloy coating on carbon steel was electrodeposited on mild steel No.20 with trivalent chromium sulfate salt containing electrolyte,and the corrosion resistance in 3.5%NaCl solution of coatings deposited with different processes was investigated by means of potentiodynamical polarization and electrochemical impedance spectroscopy(EIS) measurements. The experimental results showed that the optimal deposition parameters were as following: FeSO_4·7H_2O 15 g/L,NiSO_4·6H_2O 8 g/L,Cr_2(SO_4)_3-6H_2O 200g/L,C_6H_8O·7H_2O 70g/L,current density 4 A/dm~2,temperature 55℃.The corrosion rate of the coating in 3.5%NaCl solution was 73.2 mg·m~(-2)·h~(-1),which was 23.3%lower than that of base material.