Microarc oxidation(MAO)is an effective surface treatment method for Ti alloys to allow their application in extreme environments.Here,binary electrolytes consisting of different amounts of sodium phosphate and sodium silicate were designed for MAO.The surface mor-phology,composition,and properties of MAO coatings on Ti-6Al-4V alloy treated in 0.10 mol/L electrolyte were investigated to reveal the ef-fect of PO43-and SiO32-on the growth kinetics of the MAO coatings,using scanning electron microscopy,transmission electron microscopy,X-ray diffraction,and potentiodynamic polarization.The results showed that PO43-is beneficial for generating microarcs and forming pores with-in the coating,resulting in a thick but porous coating.SiO32-facilitates the blocking of pores in the outer deposition layer and impedes the gen-eration of microarcs,resulting in a thin dense coating.The thickness,density,phases content,and polarization resistance of the MAO coatings are primarily affected by the intensity of microarcs for low SiO32-contents,and by the number of microarcs when the SiO32-content is suffi-ciently high.The thickness of MAO coatings obtained in P/Si electrolytes shows a piecewise linear increase with increasing process time dur-ing the three stages of microarc discharge.SiO32-is beneficial to the density increase of the coating formed in the previous stage of microarcs discharge,but slows down the growth of the coating formed in the next stage.

Dajun Zhai;Tao Qiu;Jun Shen;Keqin Feng

College of Materials Science and Engineering,Chongqing University,Chongqing 400044,China;School of Mechanical Engineering,Sichuan University,Chengdu 610065,China

矿物冶金与材料学报

[1]Dajun Zhai;Tao Qiu;Jun Shen;Keqin Feng-.Growth kinetics and mechanism of microarc oxidation coating on Ti-6Al-4V alloy in phosphate/silicate electrolyte)[J].矿物冶金与材料学报,2022(11):1991-1999

microarc,Microarc,microarcs

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