Electrolytic Passivation of Nitinol Shape Memory Alloy in Different Electrolytes  

作　　者：SU Xiang-dong WANG Tian-min HAO Wei-chang HE Li 

机构地区：[1]Center of Materials Physics and Chemistry, Beijing University of Astronautics and Aeronautics, Beijing 100083, China [2]Guizhou Academy of Science, Guiyang 55000, China

出　　处：《Chinese Journal of Aeronautics》2006年第B12期113-118,共6页中国航空学报（英文版）

基　　金：Local Governmental Foundation of Guizhou province (2142005)

摘　　要：The corrosion behavior of the nitinol alloy was studied in various corrosion media of different Cl^- ion concentrations. The results demonstrate that the Cl^- ion concentration has significant influences on the corrosion behavior of the nitinol alloy. In order to enhance the corrosion resistance, protective films were generated on the surface of the nitinol alloy by means of the electrochemical passivation method, for which five different electrolytic solutions were investigated. The surface analysis indicates full growth of all samples passivated in the different electrolytic solutions with layers, however, showing different morphological features. Without any defects like micro-cracks and pores, the surface of the samples passivated in the molybdate solution turns out smoother and denser than those passivated in other solutions. It is shown that the electro-chemical passivation will reduce Ni content but increase Ti content in the surface, reaching the Mole ratio of Ti：Ni = 9.01：1 on the outermost surface. Potentiodynamic polarization test demonstrates that the samples electrochemically passivated in the molybdate solution present a significant increase in breakdown potential due to titanium enrichment on the outermost surface.The corrosion behavior of the nitinol alloy was studied in various corrosion media of different Cl^- ion concentrations. The results demonstrate that the Cl^- ion concentration has significant influences on the corrosion behavior of the nitinol alloy. In order to enhance the corrosion resistance, protective films were generated on the surface of the nitinol alloy by means of the electrochemical passivation method, for which five different electrolytic solutions were investigated. The surface analysis indicates full growth of all samples passivated in the different electrolytic solutions with layers, however, showing different morphological features. Without any defects like micro-cracks and pores, the surface of the samples passivated in the molybdate solution turns out smoother and denser than those passivated in other solutions. It is shown that the electro-chemical passivation will reduce Ni content but increase Ti content in the surface, reaching the Mole ratio of Ti：Ni = 9.01：1 on the outermost surface. Potentiodynamic polarization test demonstrates that the samples electrochemically passivated in the molybdate solution present a significant increase in breakdown potential due to titanium enrichment on the outermost surface.

关 键 词：NiTi alloy Cl^- ion corrosion electrolytic passivation TiO2 coating 

分 类 号：TG174.41[金属学及工艺—金属表面处理] TG178[金属学及工艺—金属学]