目的 通过优化电解液配方和电参数输出模式，得到改性微弧氧化新工艺，制备出综合性能优良的SiO2-Al2O3复合陶瓷涂层。方法 采用碱性硅酸盐体系电解液为诱发起弧剂，加入80~150 mL/L的碱性硅溶胶溶液和60~80 g/L蔗糖等成分为辅助添加剂，同时在电参数中加入负电参数，在7A55铝合金基体表面完成了SiO2-Al2O3复合陶瓷涂层的制备。采用SEM和EDS等测试方法分析了复合陶瓷的微观形貌和组成元素，并与制备单一Al2O3陶瓷涂层的微弧氧化工艺进行对比，分析新工艺的成膜机理。结果 改性新工艺能够在7A55铝合金基体表面制备出SiO2-Al2O3复合陶瓷涂层，厚度达到100 μm以上，其制备效率相比微弧氧化制备单一Al2O3陶瓷涂层提高了2~3倍。复合陶瓷涂层由表及里，Al2O3含量增加，SiO2含量减少，表面呈致密的球形颗粒状，没有单一Al2O3陶瓷涂层的微裂纹和大量烧蚀孔洞。新工艺除了微区放电形成微区等离子弧烧结，得到Al2O3陶瓷涂层外，还有SiO2的吸附沉积，为吸附与烧结综合作用过程。结论 加入含纳米SiO2的碱性硅溶胶等成分改性电解液，有利于改善陶瓷涂层结构，提高致密性。

The work aims to obtain the modified micro-arc oxidation process by optimizing the electrolyte formula and electrical parameter output mode to prepare SiO2 and Al2O3 composite ceramic coating with excellent comprehensive properties. Alkaline silicate electrolyte was used as the arc initiator and 80~150 mL/L alkaline silica sol solution and 60~80 g/L sucrose were used as auxiliary additives to prepare SiO2 and Al2O3 composite ceramic coatings on 7A55 aluminum alloy by adding negative electrical parameters. Microstructure and elements of the composite coating were studied by test methods like SEM and EDS. The mechanism of membrane formation by new process was studied by comparing the micro-arc oxidation process used to prepare single Al2O3 ceramic coating. SiO2 and Al2O3 composite ceramic coating with thickness over 100 μm could be prepared on 7A55 aluminum alloy by modified process and the preparation efficiency was increased by 2~3 times when compared with the micro-arc oxidation process used to prepare single Al2O3 ceramic coating. The content of SiO2 and Al2O3 in the composite coating respectively decreased and increased from the coating surface to the inner side. The composite ceramic coating showed a compact surface in the form of spherical particles without cracks or micro pores which existed in the single Al2O3 ceramic costing prepared by MAO. In addition to forming micro-area plasma arc sintering by micro-area discharge to obtain Al2O3 ceramic coating, the new process also had SiO2 adsorption deposition, which was a comprehensive process of adsorption and sintering. Adding alkaline silica sol containing nano-SiO2 to modify electrolyte is beneficial to improving the structure and compactness of ceramic coating.