超声波对电沉积Ni-Al_2O_3复合镀层耐蚀性的影响

Effect of Ultrasonic on Corrosion Resistance of Electrodeposited Ni-Al_2O_3 Composite Coatings

用超声-电沉积方式制备Ni-Al_2O_3复合镀层,用扫描电子显微镜(SEM)观察镀层腐蚀前后的表面形貌,用X-射线衍射仪(XRD)分析镀层的相组成,用电化学方法测试镀层在中性及酸性腐蚀介质中的极化曲线(Tafel)及循环伏安曲线(CV),分析超声波对镀层耐蚀性的影响.结果表明,适当的超声波作用使Al_2O_3粒子均匀分散在复合镀层中,使镀层表面平整致密,降低孔隙率,并细化基质金属Ni的晶粒,提高镀层的耐蚀性;在3.5 mass%NaCl溶液中,超声-电沉积复合镀层耐均匀腐蚀及点腐蚀能力都优于单独电沉积复合镀层;在10 mass%H_2SO_4介质中,超声-电沉积复合镀层的维钝电流小,耐蚀性优于单独电沉积复合镀层.

Ni-Al_2O_3 composite coatings were prepared by ultrasonic electrodeposition in this paper.The surface morphologies before and after corrosion and the microstructure of the coatings were characterized by means of scanning electron microscopy（SEM） and X-ray diffraction（XRD）. The Tafel curves and cyclic voltammetry curves of composite coatings were measured by electrochemical workstation,and then the effect of ultrasound on the corrosion resistance of Ni-Al_2O_3 composite coatings was analyzed.The results show that,with proper ultrasonic effect,the distribution of Al_2O_3 in the coatings is reformed,the surface becomes compacter and smoother,the porosity is decreased and the nickel crystalline is also fined,the corrosion resistance of coatings is improved.In 3.5 mass%NaCl solution,the resistance to general corrosion and pitting corrosion of ultrasonic electrodeposited Ni-Al_2O_3 composite coatings were better than that of the electrodeposited ones in 10 mass%H_2SO_4,the ultrasonic-electrodeposited composite coating exhibits smaller passivation current and better corrosion resistance.