氮气流量对AZ31B镁合金表面MAO/TiN涂层性能的影响

摘要

为了提高镁合金的装饰性及耐腐抗磨性能,采用微弧氧化(MAO)和多弧离子镀技术制备了MAO/TiN复合涂层.利用SEM、XRD、纳米压痕仪及电化学工作站等考察氮气(N2)流量对涂层结构及性能的影响.结果表明:随着N2流量的增加,TiN涂层的颜色由淡黄色到金黄色再到红黄色变化,涂层表面的熔滴粒子数量增多,大尺寸颗粒数量减少,膜层更致密;涂层硬度和耐腐抗磨性能先增大后降低;当N2流量为130 mL/min时,涂层表现出较高的硬度(13.6 GPa)、较低的磨损量(0.8 mg)和自腐蚀电流密度(约1.6 μA/cm2).N2流量通过控制涂层中N/Ti原子的比例决定了涂层的颜色、微结构、物相组成及性能,涂层内部的孔隙、微裂纹等结构缺陷是导致涂层耐腐抗磨性能较差的关键因素.%To improve the decorativeness,corrosion and wear resistance of magnesium (Mg) alloys,an MAO/TiN composite coating was prepared through combing the micro-arc oxidation (MAO) with multi-arc ion plating on AZ31B Mg alloy.The effects of N2 volumetric flow rate on the structure and properties of the coating were investigated using SEM,XRD,nanometer indentation tester and electrochemical test system.The results indicate that with N2 increasing,the color of TiN layer is changed from light yellow to gold yellow and finally brownish red;the droplet particle is increased in number but the particles with larger size are reduced;and the coating becomes more denser.These cause the hardness,corrosion and wear resistance of the coating to increase first and then decrease.The coating presente higher hardness (13.6 GPa),lower wear rate (0.8 mg) and corrosion current density (1.6 μA/cm2) at 130 mL/min.The rate of N/Ti atoms is tailored through the N2 flow rate,so it can be concludes that the N2 flow rate should be responsible for the color,micro-structure,phase composition,corrosion and wear resistance of the coating.The defects like pores and cracks are playing key roles in the poor corrosion and wear resistance.