镁合金表面电弧喷涂金属耐蚀涂层性能研究

PERFORMANCE OF ELECTRIC ARC SPRAYED COATINGS ON MAGNESIUM ALLOY

采用电弧喷涂方法,在AZ91D镁合金表面制备了NiCrAl、Al金属耐蚀涂层.利用扫描电镜分析、熱震实验、盐水浸泡实验、极化曲线等手段研究了涂层的结合强度和耐蚀性能.结果表明:金属涂层与基体结合紧密,孔隙率为9.68%,在350℃反复热震30次涂层表面未出现裂纹、翘起、脱落现象;NiCrAl、Al金属涂层在3.65%NaCl+5%H2SO4水溶液腐蚀介质中均表现出良好的钝化现象,其钝化区间分别为-0.3 V^0.6 V和0.2 V^0.7 V,Al涂层的工作电流为0.38 A,而NiCrAl涂层的工作电流仅为0.043 A.

Coatings of NiCrA1 and aluminum were prepared on the surface of AZ91D magnesium alloy by electric arc spraying. The surface and cross-sectional morphology the coatings were observed by SEM, the bond strength and the corrosion performance of the coatings were also examined. The results showed that the coating possessed a good bonding to the substrate and the porosity of the coating was 9.68 %. The flaws such as crack, tilting and spall off didn＇t occur after 30 cycles of thermal-shock from 350℃ to ambient temperature. The anodic polarization curves indicated that the coatings of NiCrA1 and aluminum metal all exhibited well passivation behavior in a 3.65% NaC1 ＋ 5% H2SO4 aqueous solution. The passivation intervals were - 0. 3 - 0. 6 V and 0. 2 - 0.7 V, correspondingly the corrosion currents were 0. 38 A and 0. 043 A respectively for the coatings of aluminum and NiCrA1.