Abstract
Yttrium tantalate(YTa04)is the next generation of higher service temperature thermal barrier coatings(TBCs)materials due to its smaller volume effect in phase change,lower thermal conductivity and unique ferroelastic domain structure.However,the low fracture toughness limits its application.We first char-acterized the diffraction patterns of variants,and two variants(M1 and M2)observed in transmission electron microscopy(TEM)results were determined from four possible variants by mechanical deriva-tion.The role of Zr4+doping in ferroelastic toughening was explained in detail.With the increase of Zr4+doping concentration,the monoclinic angle β and the domain rotation angle α decrease,respectively.The spontaneous strain component and the principal strain in the main space also have a similar decreasing trend.The decrease of the ferroelastic domain inversion energy barrier is beneficial to the improvement of fracture toughness.Combining the results of Vickers indentation,we found that Zr4+could be enriched at the domain boundary to inhibit the generation of cracks.An appropriate amount of Zr4+is conducive to the improvement of fracture toughness,and the excessive Zr4+will reduce the fracture toughness due to the generation of by-product t-ZrO2.So,the optimal composition is Y0.44Ta0.44Zr0.1202 and the best fracture toughness(2.9-3.8MPa m1/2)is equivalent to the commercial 8YSZ.This result will promote the application of a new generation of TBCs.
基金项目
国家自然科学基金(11890684)
国家自然科学基金(52102142)
Foundation for Innovative Research Groups of Hunan Province(2020JJ1005)
NETL
NSTL
万方数据