Premature failure induced by non-equilibrium grain-boundary tantalum segregation in air-plasma sprayed ZrO_(2)-YO_(1.5)-TaO_(2.5)thermal barrier coatings  

作　　者：Yao Yao Di Wu Xiaofeng Zhao Fan Yang 

机构地区：[1]Shanghai Key Laboratory of Advanced High Temperature Materials and Precision Forming,Shanghai Jiao Tong University,Shanghai 200240,China [2]School of Mechanical Engineering,Shanghai Jiao Tong University,Shanghai 200240,China

出　　处：《International Journal of Minerals,Metallurgy and Materials》2022年第12期2189-2200,共12页矿物冶金与材料学报（英文版）

基　　金：financially supported by the National Natural Science Foundation of China (Nos. 51971139 and 51875341);the National Science and Technology Major Project of China (No. 2017-VI-0011-0083)

摘　　要：ZrO_(2)-YO_(1.5)-TaO_(2.5)(ZYTO)is a promising top-coat material for thermal barrier coatings(TBCs).The bulk properties of ZYTO have been reported by several studies,but its performances as TBCs are less-well understood.In this work,ZYTO TBCs were prepared by air plasma spraying(APS)and their thermal cycling performances were investigated at 1150℃.Despite of the good bulk properties,APS ZYTO TBCs present an extremely short thermal fatigue life.This is attributed to the non-equilibrium grain-boundary segregation of TaO_(2.5) induced by limited solubility and rapid quenching during APS process,resulting in a tetragonal(t)to cubic(c)and metastable-tetragonal(tm)phase transformation in ZYTO TBCs.The volume shrinkage(~0.74vol%)of phase transformation leads to many cracks at the c/tm phase boundaries after deposition.On the other hand,the formation of cubic phase with massive grain-boundary Ta segregation induces a large intergranular embrittlement and a weak bonding strength(~5.3 MPa),resulting in the premature failure of the ZYTO TBCs.

关 键 词：thermal barrier coatings air plasma spray tantalum segregation phase transformation 

分 类 号：TG174.4[金属学及工艺—金属表面处理]