[目的]探究电解液中有无氟化物和磷酸钠浓度的变化对钛合金微弧氧化膜层结构和性能的影响，考察膜层在硝酸与氢氟酸介质中的耐蚀性差异及腐蚀特点。[方法]基于含氟添加剂和不含氟添加剂的两组磷酸盐电解液，在TC4钛合金表面制备微弧氧化膜层。采用涡流测厚仪、扫描电子显微镜(SEM)、激光共聚焦显微镜(LSCM)、X射线衍射仪(XRD)、X射线光电子能谱仪(XPS)和电子探针(EPMA)分析了膜层的厚度、粗糙度、微观形貌、物相种类、元素组成及其分布，利用点滴腐蚀实验评价膜层的耐蚀性。[结果]添加氟化物或提高磷酸钠浓度均可改善膜层的致密性，且提高了膜层中金红石型TiO₂、Al₂O₃、非晶态氧化物等耐蚀相的含量。膜层在硝酸中更耐蚀。采用含氟化钾的电解液制备的膜层在两种酸性介质中均呈现出较优的耐蚀性。当磷酸钠的质量浓度为16 g/L时，膜层的耐蚀性更优。[结论]添加氟化物和提高磷酸钠浓度改善了TC4钛合金微弧氧化膜层的致密性、成分及物相，进而提高了膜层的耐蚀性。硝酸和氢氟酸介质分别以消耗性腐蚀和渗透性腐蚀为主的方式侵蚀膜层。膜层较薄且厚度一致时，在硝酸中，膜层的致密度对其耐蚀性有关键影响；在氢氟酸中，膜层的耐蚀性主要取决于成分及物相组成。

[Objective] To study the effect of the presence or absence of fluoride additive and the variation of sodium phosphate concentration in the electrolyte on the structure and properties of micro-arc oxidation(MAO) coatings on titanium alloy, and to investigate the differences of corrosion resistance and characteristics of the coatings in nitric acid(HNO₃) and hydrofluoric acid(HF) media. [Method] MAO coatings were prepared on the surface of TC4 titanium alloy in phosphate-based electrolytes with and without fluoride additive. The thickness, roughness, morphology, phase constitution, elemental distribution, and chemical states of MAO coatings were characterized by using eddy current thickness meter, scanning electron microscope(SEM), laser scanning confocal microscope(LSCM), X-ray diffractometer(XRD), X-ray photoelectron spectrometer(XPS), and electron probe X-ray micro-analyzer(EPMA), respectively. The corrosion resistance of MAO coatings was evaluated through dropping corrosion test. [Result] The addition of fluoride additive or an increase in sodium phosphate concentration enhanced the coating compactness and increased the content of corrosion-resistant phases such as rutile TiO₂, Al₂O₃, and amorphous oxides. The MAO coatings exhibited better corrosion resistance in HNO₃ than in HF. The coatings prepared with potassium fluoride showed superior corrosion resistance in both acids. A sodium phosphate concentration of 16 g/L yielded the optimal corrosion resistance. [Conclusion] The incorporation of fluoride additive and the increase in sodium phosphate concentration enhance the compactness, chemical composition, and phase structure of MAO coatings on TC4 titanium alloy, thereby improving their corrosion resistance. In HNO₃, corrosion occurs mainly through consumptive attack, where coating compactness plays a critical role; in HF, penetration-dominated corrosion prevails, and corrosion resistance of MAO coatings depends primarily on elemental composition and phase structure.