纳米二氧化钛对铸造铝铜合金微弧氧化膜层性能的影响

Effect of nano-titania on performances of micro-arc oxidation coating on cast aluminum–copper alloy

借助X射线衍射仪(XRD)、扫描电镜(SEM)、电导率测试仪、覆层测厚仪、显微硬度仪、VSP电化学工作站和数控磨损试验机等分析手段,探究在硅酸盐电解液中加入不同含量的纳米TiO2对铸造铝铜合金微弧氧化陶瓷膜层微观结构、厚度、显微硬度、耐腐蚀性及耐磨性的影响。结果表明,硅酸盐电解液中加入的纳米TiO2参与并促进了微弧氧化反应,使得膜层的缺陷减少,致密度提高,膜层中的α-Al2O3含量增加,从而改善了铸造铝铜合金微弧氧化膜层的综合性能。当纳米TiO2的添加量为3 g/L时,膜层的厚度为69μm,显微硬度达510 HV,极化电阻Rp提高了23倍,摩擦因数较低(约为0.22),耐蚀性及耐磨性较佳。

The effects of different contents of nano-TiO2 added to silicate electrolyte on microstructure, microhardness, corrosion resistance, and wear resistance of micro-arc oxidation ceramic coatings on cast aluminum–copper alloy were studied by scanning electron microscope（SEM）, X-ray diffractometer（XRD）, conductivity tester, coating thickness tester, microhardness tester, VSP electrochemical workstation, and computer numerical control wear testing machine. The results indicated that the nano-TiO2 added to silicate electrolyte takes part in and accelerates the reaction of micro-arc oxidation, leading to less defect and higher compactness of coating and increased content of α-A2lO3 in coating, improving the comprehensive performance of micro-arc oxidation ceramic coating on cast Al–Cu alloy. The coating obtained with 3 g/L nano-TiO2 has a thickness of 69 μm, microhardness 510 HV, polarization resistance（Rp） 23 times higher than the one without nano-TiO2, low friction coefficient（about 0.22）, and good corrosion and wear resistance.