镁合金微弧氧化电解液优化及耐蚀性分析

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1、摘要本文采用自制微弧氧化设备，在硅酸盐体系电解液中对AM60镁合金进行微弧氧化处理，研究了硅酸盐体系电解液的衰变规律。结果表明：硅酸盐体系是一个不稳定的微弧氧化电解液体系；对于不同的电解液，随其处理面积的增加，电导率和PH值均呈下降趋势，当PH值达到约12．7时，电解液失效；对于同一种电解液，随着电解液处理试样面积的增加，陶瓷层表面粗糙度增大。通过一系列试验得到了镁合金在铝酸钠体系及磷酸二氢钠体系电解液中微弧氧化陶瓷层的生长规律：电流密度、处理时间、频率、占空比的变化都对陶瓷层厚度及表面粗糙度产生影响

2、；电源采用恒流方式控制时，电压一时间曲线上明显分为前期的急剧上升阶段和后期的平缓上升阶段。通过电能公式Q—UIAt近似计算出微弧氧化过程中的能耗。为了在镁合金表面形成耐蚀性良好的微弧氧化陶瓷层，本文经过大量试验，确定了铝酸钠体系及磷酸二氢钠体系中的最佳工艺参数。利用NaCl中性盐雾试验及电化学测试分析膜层耐蚀性，结果显示：镁合金试样经过微弧氧化处理后，耐蚀性大大提高，腐蚀电流可减小2"-'3个数量级；对于不同电解液中进行微弧氧化所制得的陶瓷层，其耐蚀性存在明显差异，铝酸钠一硼砂复合体系电解液得到的陶瓷

3、层耐蚀性最好，磷酸钠体系电解液中得到的陶瓷层耐蚀性最差。关键词：微弧氧化，镁合金，电解液，耐蚀性AbstractTheceramiccoatingwaspreparedonthesurfaceofthemagnesiumalloy(AM60)，bythemicro—arcoxidation(MAO)treatmentusingtheself-manufacturedequipmentinthesilicateelectrolyte．Thedisciplineofsilicateelectrolytew

4、asstudiedinthepaper．Theresultindicatedthat，silicateelectrolytewasnotastableMAOelectrolytesystem．Regardingthedifferentelectrolyte，ElectricalconductivityandPHvalueweredecliningwiththeincreasingoftreatmentareas．TheelectrolytewasfailurewhenPHvaluedownto12．7

5、．Regardingtheidenticalkindofelectrolyte，Withtreatmentareasincreasing，thesurfaceroughhessofceramiclayerincreased．ThegrowthdisciplineofceramiclayeronAM60wasobtainedthroughaseriesofexperimentsinthesodiumsilicatesystemandsodiumdihydrogenphosphatesystemelect

6、rolyte：Theparametersascurrentdensity，oxidationtime，currentfrequency，occupy—emptyratioofcurrenthadobviousinfluenceonthethicknessandroughnessofceramiclayer．Whentheelectriccurrentwasfixed，thevoltagewhileprocessingisobviousdividesintotwostages：theearlierper

7、iodthevoltageincreasedgreatandlaterthevoltageraisedslightly．EnergyconsumptionofMAOprocessiscalculatedthroughelectricalenergyformula．Inordertoobtainawellcorrosionresistantlayer,massesexperimentsonmagnesiumalloyMAOweredoneinthesodiumsilicatesystemandinthe

8、sodiumdihydrogenphosphatesystemelectrolyte．Thebestprocessingparameterwasfound．ThecorrosionresistanceofmagnesiumalloyMicro-arcOxidationceramiclayerisstudiedbyneutralNaCIsaltharacorrosiontestandelectrochemicalanalysistest．Itshowsth