La(NO3)3与Ce(NO3)3比例对AZ31镁合金微弧氧化涂层显微硬度与耐磨性能的影响

针对镁合金耐磨性偏低的问题,利用微弧氧化技术在AZ31镁合金表面制备陶瓷涂层,探究微弧氧化电解液中添加La(NO3)3与Ce(NO3)3比例对AZ31镁合金微弧氧化(MAO)涂层显微硬度以及摩擦因数的影响。结果表明:AZ31镁合金微弧氧化涂层主要由MgO、MgSiO3和MgSiO4等相组成,未检测到原始添加的La和Ce等氧化物相。La(NO3)3与Ce(NO3)3添加能够降低镁合金涂层表面的微孔尺寸。随着电解液中La(NO3)3与Ce(NO3)3的添加比例增加,显微硬度呈现出先增加后降低的趋势。与未添加稀土复合盐相比,电解液添加稀土盐后微弧氧化涂层的显微硬度有所提高。添加La(NO3)3与Ce(NO3)3不同比例,涂层表面粗糙度在6.1~7.6μm范围内变化,相比未添加稀土盐获得涂层的粗糙度降低约2~3μm。电解液中添加La(NO3)3与Ce(NO3)3复合盐后,所获得的微弧氧化涂层的摩擦因数降低。

Influence of La(NO3)3/Ce(NO3)3 doping ratio on microhardness and wear resistance of micro-arc oxidation coating for AZ31 alloy

In order to solve the problem of low wear resistance of magnesium alloy,ceramic coating was prepared on the surface of AZ31 magnesium alloy by micro-arc oxidation technology.The influence of doping content of La(NO3)3 and Ce(NO3)3 in micro-arc oxidation electrolyte on microhardness and friction coefficient of magnesium alloy micro-arc oxidation(MAO)coating was investigated.The results show that the micro arc oxidation coating of magnesium alloy was mainly composed of MgO,MgSiO 3 and MgSiO 4 crystalline phases,but La and Ce oxide phases were not detected.La(NO3)3 and Ce(NO3)3 doping can reduce the micro-pore size of magnesium alloy coating surface.With the increase of doping ratio of La(NO3)3 and Ce(NO3)3 in the electrolyte,the microhardness increased first and then decreased.Compared with the original magnesium alloy,the microhardness of magnesium alloy doped with rare-earth salt was improved.With different doping content of La(NO3)3 and Ce(NO3)3,the surface roughness of the magnesium alloy coating varied from 6.1μm to 7.6μm,so the value of surface roughness was reduced by about 2~3μm compared with that without rare earth salts.The friction coefficient of micro-arc oxidation coating of magnesium alloy was slightly decreased by increasing the doping ratio of La(NO3)3 and Ce(NO3)3 in electrolyte.