Cavitation Erosion Behavior of Ni-Al Intermetallic Coatings
C. H. Yeh
- 2003年第9卷 
采用3种原子百分比Ni52Al48,Ni60Al40及Ni70Al30成分的靶材以阴极电弧放电离子被覆技术制备不同组成的Ni＿Al薄膜于AISI1045中碳钢基材表面上,并观察镀膜微结构与成分随靶材成分的变化,评估应用Ni＿Al于抗坑蚀功能方面的可行性.研究结果显示:使用上述3种靶材所获致的镀膜组成依次为Ni62Al38,Ni63Al37及Ni69Al31,镀膜镍含量随靶材镍含量增加而增加.3种镀膜的相组成均以Ni3Al为主,从富镍Ni70Al30靶材所得的镀膜尚含有部分镍相.镀膜具有极强的附着性并反映在镀膜的抗坑蚀性上.在纯水中,所有的Ni＿Al镀膜试片均能提高中碳钢基材的抗坑蚀性,约达10倍.在3.5wt%盐水与3.5wt%盐酸中亦分别有两倍以上的效果.而在这3种测试环境中,3种镀膜试片的坑蚀损失差别均不明显,无法判断镀膜组成对抗坑蚀性的影响.从动电位极化曲线可以看出,镀膜试片均能大幅提高基材在盐酸与盐水溶液中的抗蚀性,然而因坑蚀破坏而形成的孔洞会由于孔蚀而导致腐蚀加剧,造成镀膜试片在腐蚀溶液中之抗坑蚀效果低于电化学量测时所预期的保护效果.A cathodic arc plasma ion plating process was demonstrated to deposit Ni_Al film on AISI 1045 carbon steel to evaluate the cavitation protection. Three target materials with Ni52Al48, Ni60Al40, and Ni70Al30 compositions were used to reveal the microstructural of coatings. Experimental results show that the nickel content in these deposits increased with the nickel content of the target material. The major phase of deposited film was Ni3Al regardless of the target materials. All of the as_deposited films presented very strong adhesion and reflects their cavitation erosion behavior in fresh water. All coatings increased the cavitation erosion resistance of the bare substrate 10 fold. These coatings also enhanced the cavitation resistance 2_fold or greater in 3.5 wt.% NaCl and 3_fold in 3.5 wt.% HCl electrolyte. The potentiodynamic polarization data of coated specimens in these two electrolytes indicated that the coated specimens exhibited higher corrosion potential and lower corrosion current density than the bare substrate material. It is believed that the cavitation erosion induced pitting corrosion into the substrate accelerated the mass loss rate of the substrate.