Study on Thermal Stability of High-Entropy Bisilicate Materials
Yb2Si2O7 and high-entropy bisilicate powders(Yb0.25Y0.25Lu0.25Er0.25)2Si2O7,(Yb0.2Y0.2Lu0.2Er0.2Sc0.2)2Si2O7,(Yb0.2Y0.2Lu0.2Er0.2-Ho0.2)2Si2O7 were prepared by solid phase reaction.The phase composition,coefficient of thermal expansion,thermal conductivity,and elastic modulus of the four ceramic blocks were analyzed before and after heat preservation treatment.The results show that the coefficient of thermal expansion and thermal conductivity of high-entropy(Yb0.25Y0.25Lu0.25Er0.25)2Si2O7 are similar to those of Yb2Si2O7,and the elastic modulus is increased by 29.75％.Compared with(Yb0.25Y0.25Lu0.25Er0.25)2Si2O7,the coefficient of thermal expansion and thermal conductivity of(Yb0.2Y0.2Lu0.2Er0.2Sc0.2)2Si2O7 are decreased by 5.59％and 24.78％,respectively.Compared with(Yb0.25Y0.25Lu0.25Er0.25)2Si2O7,the coefficient of thermal expansion of(Yb0.2Y0.2Lu0.2Er0.2Ho0.2)2Si2O7 is increased by 14.24％and the thermal conductivity is decreased by 15.51％.This indicates that the thermal conductivity of(Yb0.2Y0.2Lu0.2Er0.2Ho0.2)2Si2O7 with Ho elements decreases,and the increased coefficient of thermal expansion is closer to that of the substrate CMC.After holding at 1200 and 1300 ℃ for 10,30 and 50 h,Yb2Si2O7,(Yb0.25Y0.25Lu0.25Er0.25)2Si2O7,(Yb0.2Y0.2Lu0.2Er0.2Sc0.2)2Si2O7 and(Yb0.2Y0.2Lu0.2Er0.2Ho0.2)2Si2O7 all exhibit good high temperature phase stability,their coefficients of thermal expansion decrease and remain close to that of the substrate CMC,and their elastic modulus is increased with the increase in the holding time.
high-entropy bisilicatethermal environment barrier coatingthermal conductivitycoefficient of thermal expansionelastic modulus
NETL
NSTL
万方数据
