Corrosion Resistance and High-temperature Oxidation Behavior of Micro-arc Oxidation Ceramic Coating on High Niobium gamma-TiAl Alloy

Pan, M; Xu, JL; Luo, JM

Xu, JL (reprint author), Nanchang Hangkong Univ, Natl Def Key Disciplines Lab Light Alloy Proc Sci, Nanchang 330063, Jiangxi, Peoples R China.; Xu, JL (reprint author), Nanchang Hangkong Univ, Sch Mat Sci & Engn, Nanchang 330063, Jiangxi, Peoples R China.

CHINA SURFACE ENGINEERING, 2019; 32 (5): 78

Abstract

The micro-arc oxidation (MAO) technique was used to prepare in-situ ceramic coating on the surface of high niobium gamma-TiAl alloy in sodium silicate and potassium hydroxide solution to improve the high-temperature oxidation resistance. The SEM, XRD, XPS, electrochemical workstation and box-type resistance furnace high-temperature oxidation test were used to analyze the surface and cross section morphologies, phase composition, elemental chemical bonding state, corrosion resistance and high-temperature oxidation behavior of the coating, respectively. The results of XRD and XPS show that the ceramic coating is mainly composed of Al2TiO5, SiO2 and Nb2O5. The coating has a good interface with the substrate, with a thickness of 2.15 mu m. After micro-arc oxidation treatment, the corrosion resistance of high niobium gamma-TiAl alloy in 3.5% NaCl solution is improved by nearly one order of magnitude. The oxidation weight gain of the coated sample at 800-900 degrees C is only 8.9%-37.5%. The oxidative activation energy of the uncoated sample increases from 247.79 kJ/mol to 574.41 kJ/mol for the coated sample due to the formation of the MAO coating.

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