Fe-20Cr溅射纳米涂层的腐蚀电化学性能研究

利用电化学方法与表面分析技术，考察了平面磁控溅射Fe—20Cr纳米涂层的腐蚀电化学性能及耐蚀机制．研究表明，尽管溅射纳米涂层钝化膜的溶解速度高于铸态合金，但其钝化趋势较强，即使在含有0．5mo1／L NaCl的H2SO4溶液中仍能自钝化，而此时铸态合金的钝化趋势非常微弱；纳米涂层的耐点蚀能力也远优于铸态合金；晶粒细化以及铬元素分布均匀性是决定溅射纳米涂层耐点蚀能力的关键因素．

STUDY ON THE ELECTROCHEMICAL CORROSION BEHAVIOR OF SPUTTERED Fe - 20Cr NANOCRYSTALLINE COATING

The electrochemical corrosion behavior of Fe-20Cr sputtered coating has been investigated by electrochemical measurement and surface analysis techniques such as SEM,STM and EPMA.The sputtered coating with nanometer grains showed the higher corrosion rate in acid solution with and without Cl - even through a passive film formed on this coating automatically.On the other hand,the corrosion rate of Fe-20Cr cast alloy was lower and a passive film only formed when anodic potential was positive enough.The further research realized that nanocrystallization,content and distribution of Cr in substrate and passive film were the main factors that affected the corrosion resistance of these materials.The sputter coating with smaller grain had a more amount of grain boundary where the amount of active atoms was more than that of the other area.This resulted in the higher corrosion rate of the sputter coating.The homogenous distribution of Cr element in the sputter coating make it easy to form a passive film on its surface.The lower concentration of Cr in the passive film of sputter coating results the higher diffusion limited current density on the passive film.