The Influence Of Er Doping On Thermophysical Properties Of (Y_1-xEr_x)₃Al₅O₁₂ Ceramics

Yttrium aluminum garnet Y₃Al₅O₁₂?YAG?,YAG has excellent phase stability and thermal stability,avoiding the drawbacks of traditional zirconia high temperature phase transformation.It is a new type of thermal barrier coating material.The crystal structure and thermophysical properties of Y₃Al₅O₁₂ can be further improved by doping rare earth elements to modify the introduction point defects.In this experiment,(Y_1-xEr_x)₃Al₅O₁₂?x=0,0.1,0.3,0.5,0.7,0.9,1?ceramic powders were synthesized from Er₂O₃,Y₂O₃ and Al?OH?₃ by solid-phase synthesis at 1100?,and(Y_1-xEr_x)₃Al₅O₁₂2 ceramic materials were sintered at 1600?.X-ray diffraction?XRD?,scanning electron microscopy?SEM?,pycnometer m ethods,high temperature thermal expansion instrument,Neumann-Kopp law,las er thermal conductivity instrument,microhardness tester and electronic universal testing machine were used to characterize the phase structure,micro-structure,bulk density,thermal expansion coefficient,thermal capacity,thermal diffusivity,hardness and strength of ceramic materials.XRD results show that the phase structure of(Y_1-xEr_x)₃Al₅O₁₂?x=0,0.1,0.3,0.5,0.7,0.9,1?ceramics sintered at 1600?for 5 hours is single garnet structure.At the same time,the lattice parameters decrease with the doping of rare earth oxides.SEM results show that the microstructure of(Y_1-xEr_x)₃Al₅O₁₂ ceramics sintered at1600?for 5 hours is similar,the grain boundary is clear,the grain size is 0.95¹.86?m,and the ceramics samples are relatively compact.In the range of room temperature to 1200?,The results of thermophysical properties test show that the linear change rate of(Y_1-xEr_x)₃Al₅O₁₂2 ceramics increases linearly with the increase of temperature,and the average thermal expansion coefficient is close,ranging from 8.98×10^-66 K^-11 to 9.18×10^-66 K^-1.For(Y_1-xEr_x)₃Al₅O₁₂ ceramics,the heat capacity increases with the increase of temperature and decreases with the increase of Er₂O₃ doping in the range of room temperature to 1000?.The thermal diffusivity and thermal conductivity of Y₃Al₅O₁₂ ceramics were effectively reduced by Er₂O₃doping in the range of room temperature to 1000?.The thermal diffusivity and thermal conductivity of Y₃Al₅O₁₂2 ceramics decreased first and then increased with the increase of rare earth oxide doping.In particular,for component x=0.70 in(Y_1-xEr_x)₃Al₅O₁₂ceramics,its thermal conductivity is between 4.50 Wm^-1K^-11 and 1.51 Wm^-1K^-1.The thermal conductivity decreases significantly with the increase of temperature,and is 28%lower than that of pure YAG(2.1 Wm^-1K^-1)at 1000?.The results of mechanical properties test show that the change trend of strength and hardness of(Y_1-xEr_x)₃Al₅O₁₂ ceramics is basically similar.With the increase of doping amount,the hardness increases from 14.28 GPa to 16.53 GPa,and the bending strength increases from 231.74 MPa to 324.49 MPa.The above results show that,(Y_1-xEr_x)₃Al₅O₁₂ ceramics are more suitable for high temperature thermal barrier coatings.