Cailiao Baohu (Jul 2023)

Study on the Microstructure and High Temperature Oxidation Behavior of Micro-Arc Oxidation Coating on TC4 Alloy

  • ZHAO Xinrui, WANG Shuqi, FU Boda, LU Yinsong, ZOU Yongchun, CHEN Guoliang, WANG Yaming

DOI
https://doi.org/10.16577/j.issn.1001-1560.2023.0158
Journal volume & issue
Vol. 56, no. 7
pp. 31 – 37

Abstract

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In order to improve the high temperature oxidation resistance of TC4 alloy，an anti-oxidation ceramic coating was prepared on the surface of titanium alloy by micro-arc oxidation in the NaAlO2+ Na3PO4 electrolyte system.The phase composition and microstructure of the coating were characterized by XRD，SEM and EDS，respectively.The hardness and elastic modulus of the coating were tested by nano indenter.In addition，the high temperature oxidation resistance and thermal shock resistance of the micro-arc oxidation coating were studied.Results showed that the surface of the micro-arc oxidation coating was porous.The coating was mainly composed of Al2TiO5 and rutile TiO2 phase.The nano hardness of microarc oxidation coating was (7.8 ± 0.6) GPa，significantly higher than that of TC4 alloy [(4.0 ± 0.2) GPa].After cyclic oxidation at 700 ℃for 80 h，the weight gain per unit area of micro-arc oxidation coating was only 0.73 mg/cm2，which was far less than the weight gains of TC4 alloy (20 mg/cm2)，showing good high temperature oxidation resistance.After 25 thermal shocks at 700 ℃，the coating had no scaling，indicating excellent thermal shock resistance.Hence，it could be seen that micro-arc oxidation coating could effectively prevent the diffusion of oxygen，significantly reducing the oxidation rate of titanium alloy and improving the high temperature oxidation resistance of titanium alloy.

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