摘要
采用不同偏压参数(0、-50、-100、-200、-300V)电弧离子镀(AIP)沉积铝涂层.通过扫描电子显微镜(SEM)和能谱仪(EDS)对不同参数下镀铝涂层的表面及截面特征进行分析;采用开路电位(OCP)、电化学阻抗谱(EIS)和电化学极化(EI)等电化学测试及中性盐雾实验对不同参数下的镀铝涂层防护性进行研究.结果表明:随着偏压的增大,镀铝涂层孔隙及粗糙度表现出先减小后增大的趋势.各偏压参数下的镀铝涂层试样的OCP稳定在-0.72～-0.77 V之间,电荷转移电阻在(1.50～2.98)× 104 Ω·cm2之间,自腐蚀电流密度在(1.18～5.49)× 10-6 A·cm-2之间,耐蚀性明显优于45#碳钢.经336 h盐雾实验后,各偏压参数下的镀铝涂层试样仍具有一定的防护性能,镀层及铁铝扩散层对于铁基体表现为阴极保护机制,其中偏压-200 V的镀铝涂层防护性能更优.因此,当靶电流55A、Ar压力1.0 Pa、偏压-200 V时,AIP所制备铝涂层结构致密,与基体结合良好,具有优异的防护性能.
Abstract
Al-coating is considered to be an ideal protective coating for steels.Multi-arc ion plating Al-coating is of significance for improving steel corrosion resistance,because multi-arc ion plating has ad-vantages,such as non-toxicity,non-pollution,low-energy consumption,and easy operation etc.In this pa-per,multi-arc ion plated Al-coatings on 45# carbon steel were prepared by setting different bias parame-ters(0,-50,-100,-200,-300 V).Their surface and cross-section morphologies were characterized by scanning electron microscope(SEM)and energy-dispersive X-ray spectroscopy(EDS).The protective properties of the coatings prepared by different bias parameters were studied by electrochemical means,such as open circuit potential(OCP)measurement,electrochemical impedance spectroscopy(EIS),elec-trochemical polarization(El)measurement and neutral salt spray test.The results showed that the num-ber of pores and roughness of the Al-coatings decrease first then increase with the increasing bias voltag-es.Correspondingly,their OCPs,charge transfer resistances and free-corrosion current densities were stable between-0.72～-0.77 V,(1.50～2.98)×104 Ω·cm2,and(1.18～5.49)·10-6 A·cm-2,respectively.It is worthy noted that the corrosion resistance of the Al-coatings was obviously better than that of the bare 45# carbon steel.Being subjected to neutral salt spray test for 336 h,the Al-coatings still exhibit protec-tive performance to certain extent because of cathodic protection mechanism,especially the Al-coating prepared by-200 V had excellent protective properties.In conclusion,the Al-coating,which was pre-pared by the following process parameters i.e.,target current 55 A,Ar gas pressure 1.0 Pa,and bias volt-age-200 V,is compact with better adhesive to the substrate thus exhibits the best protective perfor-mance.
维普
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