Effects of vacuum pre-oxidation process on the thermally grown oxides layer of CoCrAlY high temperature corrosion resistance coating
Thermal barrier coatings (TBCs) are widely applied for the cutting-edge fields such as aerospace, weapons and ships.The high temperature lifespan of Electron Beam Physical Vapor Deposition (EB-PVD) is much longer than that of thermal spraying whose lifetime of high temperature oxidation will be increased when adding the specific process of vacuum pre-oxidation before high temperature service.This paper explores the influence of vacuum pre-oxidation process on the phase transformation of thermally grown oxides (TGO) of the CoCrAlY high temperature corrosion resistance coatings produced by means of High Velocity Oxygen Fuel (HVOF) on the nickel-based superalloy substrate.And this study indicates that those coatings without vacuum pre-oxidation process that are subjected to the initial high temperature oxidation, for TGO contains a lot of chromium oxides, cobalt oxides and spinel oxides in addition to alumina.Furthermore,the quantity of the formation of alumina is strongly dependent on the partial pressure of oxygen;while the CoCr2O4 spinel oxides can be formed in the conditions of both high partial pressure of oxygen at the initial isothermal oxidation and the chemical reaction at the subsequent stage of isothermal oxidation.After the appropriate vacuum pre-oxidation process, the main phases in the TGO are Al2O3 with lower Y elements distributing sporadically the Al2O3 with higher Y elements, and the grain sizes of the alumina are ranged from 0.4 μm to 1 μm, and the spinel oxides cannot be found in the TGO.After isothermal oxidation for 100 hours, the grain size of the alumina reaches to 1 μm approximately, a small amount of CoCr2O4 with the porous microstructure and Cr2O3 distribute sporadically in the adjacent of the continuous alumina.Additionally, the growth rate of TGO becomes lower than those without vacuum pre-oxidation process.
thermal barrier coatings vacuum pre-oxidation process High Velocity Oxygen Fuel (HVOF) thermally grown oxides (TGO) spinel oxides
HAN Yujun YE Fuxing
School of Materials Engineering, Nanjing Institute of Technology, Nanjing 211167,PR China Materials Science and Engineering, Tianjin Key Laboratory of Advanced Joining Technology,Tianjin Uni
国际会议
北京
英文
266-275
2014-10-11（万方平台首次上网日期，不代表论文的发表时间）