镁合金表面等离子喷涂Al涂层及耐蚀性研究

Study on Plasma Spraying and Corrosion Resistance of Al Coating Deposited on Mg Alloy

利用等离子喷涂技术在AZ91D镁合金表面制备了Al涂层,并对所制备的涂层利用SEM进行微观形貌观察,利用XRD进行涂层物相分析,利用拉伸法测量涂层与基体的结合强度,利用光学显微镜法测量涂层的孔隙率,利用中性盐雾实验测试涂层的耐腐蚀性能。结果表明:在AZ91D镁合金表面等离子喷涂制备的Al涂层比较致密,涂层的孔隙率为3.36%;涂层与基体结合良好,涂层与基体间的结合强度为20.9MPa;涂层的耐蚀性很好,在中性盐雾条件下涂层在900h后仍完好无损;Al涂层中性盐雾试验后的腐蚀产物成份,主要为Mg(OH)2、Al(OH)3、Mg2(OH)3Cl·4H2O和Mg2CO3(OH)2·3H2O等物质。

Al coating is deposited on the AZ91D Mg alloy substrate by plasma spraying. Scanning electron microscope （SEM） and X-ray diffraction （XRD） are used to identify the phases and study the morphology respectively. The bonding strength and porosity ratio of the coating are measured by stretching method and optical mi-croscope （OM）. The corrosion resistance ofAZ91D Mg al- loy with Al coating is evaluated by immersing in 5% NaCl salt spray test. The results show that Al coating is dense and the porosity ratio is 3.36%, the bond strength between the coating and substrate is 20.9MPa, the Al coating have good corrosion resistance, the coating can last more than 900h in salt spray test. The main components of corrosion production are Mg（OH）2, Al（OH）3, Mg2（OH）3Cl · 4H2O and Mg2CO3（OH）2· 3H2O.