退火温度对MAO-TC4钛合金表面组织及腐蚀性能的影响

通过微弧氧化技术(Micro-arc oxidation, MAO)对TC4合金进行表面处理,随后采用X射线衍射仪、场发射扫描电镜、激光共聚焦显微镜、硬度测试以及电化学腐蚀等方法研究不同退火温度下MAO-TC4合金的表面氧化膜层形貌、厚度、硬度、相结构以及电化学腐蚀行为。结果表明:随着退火温度的升高,MAO-TC4合金表面氧化膜层的显微硬度亦随之增大,当退火温度为850 ℃时,其最高显微硬度为592 HV0.2。450~850 ℃退火温度范围内,随退火温度升高,MAO-TC4合金的膜层耐腐蚀性先增加后降低;当退火温度为650 ℃时,膜层的自腐蚀电流密度为0.125 μA/cm²,耐腐蚀性能最佳。

Effect of annealing temperature on surface microstructure and corrosion properties of MAO-TC4 titanium alloy

Surface treatment of TC4 alloy was carried out by using micro-arc oxidation (MAO). The morphologies, thickness, hardness, phase structure, and electrochemistry corrosive behavior of surface oxide film on the MAO-TC4 alloy annealed at different temperatures were studied by means of X-ray diffractometer, field emission scanning electron microscope, laser confocal microscope, microhardness test and electrochemical corrosion. The results show that, with the increase of annealing temperature, microhardness of surface oxide film of the MAO-TC4 alloys increases, and when annealed at 850 ℃, the maximum hardness of 592 HV0.2 can be obtained. The film corrosion resistance of the MAO-TC4 alloy increases at first and then decreases with the increase of annealing temperature in the range of 450-850 ℃. When the annealing temperature is 650 ℃, the self-etching current density of film is 0.125 μA/cm², at which the optimal corrosion resistance is presented.