镁合金环保型阳极氧化工艺研究

通过环保型阳极氧化工艺在MB2镁合金表面获得了表面质量良好的银灰色氧化膜层，用金相显微硬度计、扫描电镜和X射线衍射等表面分析手段，研究了氧化膜层的显微硬度、截面形貌和相结构，并采用动电位扫描的电化学方法考察了氧化膜的耐腐蚀性能.结果表明：氧化膜层的主要成分为MgO、MgAl2O4、Al2O3；膜层具有多孔结构，孔径较为均匀，分为内外两层，外层为疏松层，内层为与基体结合牢固的致密层；阳极氧化电流密度和电解液中铝盐浓度是影响阳极氧化膜层性能的主要因素；所得膜层的显微硬度值高达558.4 HV，同时其耐蚀性能也远优于传统含铬DOW17工艺所成的防护膜，且所用电解液无铬无磷更为环保经济.

A NEW ENVIRONMENT-FRIENDLY ANODIZING PROCESS FOR MAGNESIUM ALLOYS

A novel silvery gray film was formed on the surface of MB2 magnesium alloy through a new environment-friendly anodizing process.The microhardness,microstructures and phase structures of ceramic coating were studied by means of microhardness instrument,SEM and XRD.The corrosion resistance of the oxide coating was investigated by dynamic potential scanning method.The results showed that the oxide coating was mainly consisted of MgO,MgAl_2O_4 and Al_2O_3.The structure of the anodized film was uniform and porous,which included two layers:The outer layer was loose and the inner layer was a compact layer that conjoined strongly to the substrate.The properties of anodized film were dependent on the anodizing current intensity and the concentration of the aluminium ions.The microhardness of the anodized film was 558.4 HV.The new process was more effective to improve corrosion protection of magnesium and its alloys than the film which was obtained by the traditional DOW17 process.And its electrolyte used contained no Cr and P,which was more environment-friendly and economical.