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采用脉冲电镀法在Q235钢表面制备Ni-Cr-Mo合金镀层。利用扫描电镜(SEM)、辉光放电光谱仪(GDS)、Tafel曲线和电化学阻抗谱(EIS)考察了施镀时间对镀层表面形貌、形成过程、镀层厚度、元素含量和耐蚀性的影响。结果表明:镀层由粒状结构形核、长大并逐层叠加形成;镀层的形成存在一个孕育期,孕育期后一定时间内镀层增厚较为困难,施镀时间继续增大,镀层可顺利增厚。随施镀时间的增大,镀层镍含量增大,铬含量减小,钼含量减小。在3.5%NaCl溶液中,镀层耐蚀性先增强后减弱。施镀时间为50 min时制备的镀层具有最大的自腐蚀电位(-0.355 V)、最小的腐蚀电流密度(0.006μA·cm~(-2))和最大的电荷转移电阻(26544Ω·cm~2),耐蚀性最好。
Preparation of Ni-Cr-Mo alloy coating on Q235 steel by pulse plating. The effect of plating time on the surface morphology, formation process, coating thickness, element content and corrosion resistance of coating was investigated by scanning electron microscope (SEM), glow discharge spectrometer (GDS), Tafel curve and electrochemical impedance spectroscopy (EIS) . The results show that the coatings are formed by granular structure nucleation, growth and layer by layer. The formation of coating has a period of incubation. It is difficult to thicken the coating within a certain period of time after the incubation period. The plating time continues to increase, and the coating thickness can be smoothly increased . With the increase of plating time, the content of nickel increases, the content of chromium decreases and the content of molybdenum decreases. In 3.5% NaCl solution, the corrosion resistance of the coating first increases and then decreases. The coating prepared at 50 min had the highest corrosion potential (-0.355 V), the lowest corrosion current density (0.006 μA · cm -2) and the maximum charge transfer resistance (26544 Ω · cm -2 ), The best corrosion resistance.