以TC4钛合金为基体,在硅酸钠电解液中进行微弧氧化(MAO).电解液的主要成分为Na2SiO3、Na3PO4和NaOH,工艺条件为:电压450V,频率500 Hz,占空比30％,时间5min.通过向电解液中添加0.5 g/L K2CrO4对微孤氧化膜层进行着色.采用涡流测厚仪、维氏硬度计、扫描电镜、X射线荧光光谱分析仪以及中性盐雾试验等,研究了K2CrO4添加剂对膜层厚度、显微硬度和形貌等性能的影响.结果表明,所得微弧氧化膜层为典型的不规则多孔氧化物陶瓷膜层,显微硬度和耐蚀性明显优于基材.在电解液中加入K2CrO4后,MAO膜层由灰色转变为深黄色；K2CrO4使膜层粗糙度和孔径增大,与基体结合处的缺陷减少,结合力增强；膜层的脆性和内应力降低,耐蚀性增强.%Micro-arc oxidation (MAO) was carried out in sodium silicate electrolyte using TC4 titanium alloy as the substrate.The main components of electrolyte are Na2SiO3,Na3PO4,and NaOH.The process conditions are as follows:voltage 450 V,frequency 500 Hz,duty cycle 30％,and time 5 min.0.5 g/L K2CrO4 was added to electrolyte for the coloring of MAO coating.The effect of K2CrO4 as additive on the performances of MAO coating such as thickness,microhardness,and morphology was studied by eddy current thickness meter,Vickers hardness tester,scanning electron microscopy,X-ray fluorescence spectroscopic analysis,and neutral salt spray testing.The results show that the obtained MAO coating is typically irregular-porous oxide ceramic coating,and has higher microhardness and better corrosion resistance than substrate.The addition of K2CrO4 to the electrolyte changes the color of MAO coating from gray to dark yellow,increases the roughness and pore size of MAO coating,reduces the number of defects between MAO coating and substrate,strengthens the adhesion of MAO coating to substrate,and decreases the brittleness and internal stress,improving corrosion resistance of MAO coating.
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