Influence of anions in phosphate and tetraborate electrolytes on growth kinetics of microarc oxidation coatings on Ti6Al4V alloy  

磷酸盐和四硼酸盐电解质中阴离子对Ti6Al4V合金微弧氧化膜生长动力学的影响

作　　者：Xiao-ming WANG Fu-qin ZHANG 王小明;张福勤(中南大学粉末冶金研究院,长沙410083;邵阳学院机械与能源工程学院,邵阳422000;邵阳学院高效动力系统智能制造湖南省重点实验室,邵阳422000)

机构地区：[1]Powder Metallurgy Research Institute,Central South University,Changsha 410083,China [2]Department of Mechanical and Energy Engineering,Shaoyang University,Shaoyang 422000,China [3]Key Laboratory of Hunan Province for Efficient Power System and Intelligent Manufacturing,Shaoyang University,Shaoyang 422000,China

出　　处：《Transactions of Nonferrous Metals Society of China》2022年第7期2243-2252,共10页中国有色金属学报（英文版）

摘　　要：The growth kinetics of microarc oxidation(MAO)coatings on Ti6Al4V alloy was studied by designing an electrolyte with low PO_(4)^(3−)content and high B_(4)O_(7)^(2−)content,using scanning electron microscopy,transmission electron microscopy,X-ray diffraction,and potentiodynamic polarization.The results showed that B_(4)O_(7)^(2−)increased the spark intensity and dissolved most of the oxides at high temperatures.Then,a thicker barrier layer at the coating/substrate interface was produced,which increased the polarization resistance of the coating.PO_(4)^(3−)at a low concentration also promoted the uniform growth of the MAO coating and the formation of hat-shaped holes in the outer deposition layer.The thickness of the MAO coatings obtained in Na_(2)B_(4)O_(7) electrolytes exhibited an exponential increase with time at spark discharge stage,while that of the MAO coating obtained in phosphate–tetraborate electrolytes showed a linear trend as the PO_(4)^(3−)content increased.通过设计低含量PO_(4)^(3−)和高含量B_(4)O_(7)^(2−)离子电解液,采用扫描电镜、透射电镜、X射线衍射和动电位极化等方法研究Ti6Al4V合金微弧氧化(MAO)涂层的生长动力学。结果表明,B_(4)O_(7)^(2−)离子提高放电火花强度,在高温下溶解大部分氧化物,在涂层/基态界面上形成较厚的阻挡层,从而提高涂层的极化电阻。低浓度PO_(4)^(3−)离子促进微弧氧化涂层的均匀生长和外沉积层帽状孔洞的形成。在火花放电阶段,Na_(2)B_(4)O_(7)电解液中形成的MAO涂层厚度随时间呈指数增长,而在磷酸盐和四硼酸盐混合电解液中形成的MAO涂层厚度随PO_(4)^(3−)离子含量的增加呈线性增长趋势。

关 键 词：Ti6Al4V alloy microarc oxidation PHOSPHATE tetraborate ELECTROLYTE ANIONS growth kinetics 

分 类 号：TG174.4[金属学及工艺—金属表面处理]