Preparation Of Micro Arc Oxidation Ceramic Coatings On Ti80Alloy And Its Corrosion Resistance And High Temperature Oxidation Resistance

In order to solve the problem of corrosion and thermal oxidation of Ti80alloy in its practical application, in this paper, ceramic coatings with highperformance in corrosion resistance, high temperature oxidation resistance andthermal shock resistance were prepared on Ti80alloy by optimizing theparameters of MAO.When power supply output voltage, positive and negative phase duty ratio,pulse frequency, oxidation time and the concentration of electrolyte Na3PO4were480V,45%,50%,60Hz,30min6~16g/L respectively, the thickness ofcoatings prepared is in the range of2~8μm and shear strength in the range of14.88~32.26MPa. And the thickness, the size of holes on the surface and relativecontent of rutile TiO2increase with the increase of concentration, however, theshear strength and the number of holes decrease.Micro-arc oxidation makes self-corrosion potential of Ti80alloy movepositively.When the concentration of Na3PO4is12g/L, the coating has maximumself-corrosion potential, rising by0.3837V compared with Ti80alloy, whoseself-corrosion current density is only1/124of that of Ti80alloy. LY12aluminum alloy/coatings has less galvanic current density, potential differenceand mass loss percentage than LY12aluminum alloy/Ti80alloy. When theconcentration of electrolyte is12g/L, galvanic current density and mass losspercentage of aluminum alloy/coating are only1/5and3/5of those ofaluminum alloy/Ti80alloy, galvanic corrosion sensitivity level decreases from Dto C.After oxidation test under50, oxidation scale appears on the surface ofsubstrate, while cracks appear on the surface of coatings. And the bigger theelectrolyte concentration, the more cracks increased on the surface of coating.The relative content of TiO2increases obviously, while the diffraction peakintensity of substrate decreases after oxidation test. The weight gain of Ti80alloy is greater than that of coating specimens obviously And the bigger theelectrolyte concentration, the less weigh gain of specimens, the higher theresistance to high temperature oxidation. Substrate’s surface turns from silverywhite to violet after thermal shock test, which means it is oxidized seriously,while coatings’surfaces become yellow, obvious cracks appear but there is nophenomenon of flake off. And the bigger the electrolyte concentration, the more cracks on the surface of coatings, the worse thermal shock performance.The relative content of TiO2increases while the diffraction peak intensity ofsubstrate decreases after thermal shock test. The thermal shock resistance ofcoatings is related to shear strength.