热处理对低压冷喷涂铜铝复合涂层耐腐蚀性能的影响

Effects of Heat-Treatment on Corrosion Resistance of Cu-Al Composite Coating Prepared by Low Pressure Cold Spraying

通过低压冷喷涂技术在45号钢基体表面制备了铜铝复合涂层,然后在不同温度对涂层进行了热处理。采用静态压痕法和扫描电镜(SEM)表征热处理前后涂层的显微硬度和微观形貌;采用腐蚀浸泡试验、铜加速乙酸盐雾(CASS)试验研究热处理前后涂层的耐腐蚀性能。结果表明:当热处理温度为450℃时,铜铝复合涂层内铜、铝元素发生了明显的扩散现象,涂层具有良好的力学性能和耐腐蚀性能,其空隙率和腐蚀速率分别为0.44%和0.55g/(m^(2)·h),耐腐蚀等级达六级标准。热处理可降低铜铝复合涂层内部孔隙率,涂层致密的组织结构与涂层表面的腐蚀产物对腐蚀介质起到良好的阻挡作用,从而为基体提供长久有效的防护。

Cu-Al composite coatings were prepared on the surface of 45 steel substrate by low pressure cold spraying,and then the coatings were heat-treated at different temperatures.Static indentation method and scanning electron microscopy(SEM)were used to characterize the micro-hardness and micro-morphology of the coating before and after heat-treatment.The corrosion resistance of the coating before and after heat-treatment was studied by corrosion immersion test and copper accelerated acetate spray test(CASS).The results show that when the heattreatment temperature was 450℃,the elements of copper and aluminum in coatings were obviously diffused,and the coating had good mechanical properties and corrosion resistance,whose porosity and corrosion rate were 0.44% and 0.55 g/(m^(2)·h),respectively,and corrosion resistance reached the sixth grade standard.Heat-treatment can reduce the internal porosity of the coating,and the dense structure of the coating and the corrosion products on the surface of the coating can well block corrosive media,thereby providing long-term effective protection for the substrate.