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采用SHS反应火焰喷涂技术,把Al-TiO2-B2O3铝热反应剂引入喷涂材料中,采用机械球磨和聚乙烯醇(PVA)造粒制成喷涂复合粉末,在镁合金AZ31B表面制备Al2O3基复相陶瓷涂层。利用XRD和SEM分析了喷涂复合粉末和复合陶瓷涂层的组成及形貌,并对涂层的热震性能、致密性、显微硬度和耐磨性进行测试。结果表明:复合粉末经12 h球磨后发生铝热反应,粉末呈球形及少量片状,造粒后形成相互包覆的球形结构。涂层中生成TiB2、MgAl2O4等新相。该复合涂层熔化较充分,涂层与基体结合紧密,界面处Mg元素有扩散。复合涂层热震次数可达45次,清漆封孔后,孔隙率为0%,致密性很好,最大显微硬度值达1224 HV0.1,耐磨性比镁合金基体提高8倍以上。涂层热震性能、致密性、显微硬度和耐磨性明显优于普通热喷涂陶瓷涂层。
The Al-TiO2-B2O3 thermite reagent was introduced into the sprayed material by SHS reactive flame spray technique. Sprayed composite powder was prepared by mechanical ball milling and polyvinyl alcohol (PVA) granulation. The Al2O3 complex phase was prepared on the surface of AZ31B magnesium alloy Ceramic coating. The composition and morphology of sprayed composite powders and composite ceramic coatings were analyzed by XRD and SEM. The thermal shock resistance, compactness, microhardness and wear resistance of the coatings were tested. The results showed that the composite powders were subjected to the aluminothermic reaction after being ball milled for 12 hours. The powders were spherical and with a few flakes. After the powders were pelletized, spherical structures were formed. The coating produces TiB2, MgAl2O4 and other new phases. The composite coating melts more fully, and the coating is tightly combined with the substrate, and the Mg element in the interface is diffused. The number of thermal shocks of the composite coating can reach 45 times, the porosity is 0% after the varnish is sealed, the compactness is very good, the maximum microhardness value reaches 1224 HV0.1, and the wear resistance is more than 8 times higher than that of the magnesium alloy substrate. The thermal shock resistance, compactness, microhardness and wear resistance of the coating are obviously better than the ordinary thermal sprayed ceramic coating.