La(NO3)3/Ce(NO3)3比对镁合金MAO涂层表面形貌和耐蚀性能影响

Influence of La(NO3)3/Ce(NO3)3 Doping on the Surface Morphology and Corrosion Resistance Behavior of TC4 MAO Coating

尝试利用微弧氧化(MAO)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La(NO3)3/Ce(NO3)3掺杂含量对AZ31镁合金微弧氧化涂层润湿性能和电化学行为的影响规律。在已优化的硅酸盐电解液体系和电化学参数条件下对AZ31镁合金微弧氧化处理,研究La(NO3)3/Ce(NO3)3掺杂含量变化对微弧氧化涂层相组成、润湿角、表面粗糙度以及电化学性能的影响作用。在微弧氧化电解液La(NO3)3/Ce(NO3)3掺杂镁合金涂层主要由Mg、MgO、MgSiO3和MgSiO4等晶相组成,未检测到原始添加的La和Ce等氧化物相。La(NO3)3/Ce(NO3)3掺杂对镁合金涂层表面形貌和粗糙度影响不大,但对润湿角影响较大。在La(NO3)3/Ce(NO3)3掺杂比不同的条件下,镁合金涂层表面粗糙度在6~13μm。在电解液中引入La(NO3)3/Ce(NO3)3后,镁合金涂层的极化曲线向正电位方向移动。与镁合金基体相比,镁合金涂层的腐蚀电位增加,腐蚀电流密度降低,腐蚀电流降低约为一个数量级。

In order to solve the problem of low corrosion resistance of magnesium alloy,this paper attempted to prepare ceramic coating on AZ31 magnesium alloy surface by micro-arc oxidation technology,then to investigate the influence of La(NO3)3/Ce(NO3)3 doping content on the wettability and electrochemical behavior of AZ31 alloy micro-arc oxidation coating.Micro-arc oxidation treatment for AZ31 magnesium alloy was treated through optimized silicate electrolyte system and electrochemical parameters.The influence of La(NO3)3/Ce(NO3)3 doping content on phase composition,wetting angle,surface roughness and electrochemical performance of micro arc oxidation coating was researched.In the electrolyte La(NO3)3/Ce(NO3)3 doped magnesium alloy coating was mainly composed of Mg,MgO,MgSiO3 and MgSiO4 crystal phases,and the original doped La and Ce oxide phases are not detected.La(NO3)3/Ce(NO3)3 doping had little effect on the surface morphology and roughness of magnesium alloy coating,but it had a great influence on the wetting Angle.The surface roughness of magnesium alloy coating varied in the range of 6~13μm,even if the doping amount was different.When La(NO3)3/Ce(NO3)3 was introduced into the electrolyte,the polarization curve of the magnesium alloy coating moved towards the positive potential direction.Compared with magnesium alloy substrate,the corrosion potential of magnesium alloy coating increased and the corrosion current density decreased.The corrosion current decreased by an order of magnitude.