Yttrium aluminum perovskite(YAl O3)is a promising candidate material for environmental barrier coatings(EBCs)to protect Al2 O3 f/Al2 O3 ceramic matrix composites(CMCs)from the corrosion of high-temperature water vapor...Yttrium aluminum perovskite(YAl O3)is a promising candidate material for environmental barrier coatings(EBCs)to protect Al2 O3 f/Al2 O3 ceramic matrix composites(CMCs)from the corrosion of high-temperature water vapor in combustion environments.Nevertheless,the relatively high thermal conductivity is a notable drawback of YAl O3 for environmental barrier coating application.Herein,in order to make REAl O3 more thermal insulating,a novel high-entropy rare-earth aluminate ceramic(Y0.2Nd0.2Sm0.2Eu0.2Er0.2)AlO3 was designed and synthesized.The as-prepared(Y0.2Nd0.2Sm0.2Eu0.2Er0.2)AlO3 ceramic possesses close thermal expansion coefficient(9.02×10-6/oC measured from room temperature to 1200℃)to that of Al2 O3.The thermal conductivity of(Y0.2Nd0.2Sm0.2Eu0.2Er0.2)AlO3 at room temperature is 4.1 W·m-1K-1,which is almost one third of the value of YAl O3.Furthermore,to effectively prevent the penetration of water vapor from possible pores/cracks of coating layer,which are often observed in T/EBCs,a tri-layer EBC system REAl O3/RE3 Al5 O12/(Al2 O3 f/Al2 O3 CMCs)is designed.Close thermal expansion coefficient to Al2 O3 and low thermal conductivity of(Y0.2Nd0.2Sm0.2Eu0.2Er0.2)AlO3,as well as the formation of dense garnet layer at(Y0.2Nd0.2Sm0.2Eu0.2Er0.2)AlO3/Al2 O3 interface,indicate that this new type of high-entropy ceramic is suitable as a candidate environmental barrier coating material for Al2 O3 f/Al2 O3 CMCs.展开更多
ZrSiO_4 bulk was prepared by pressureless sintering process and ZrSiO_4 coating was deposited on the SiC f/Si C substrate using air plasma method. The microstructures of ZrSiO_4 bulk and ZrSiO_4 coating are both dense...ZrSiO_4 bulk was prepared by pressureless sintering process and ZrSiO_4 coating was deposited on the SiC f/Si C substrate using air plasma method. The microstructures of ZrSiO_4 bulk and ZrSiO_4 coating are both dense. A preliminary study of a water vapor corrosion test for ZrSiO_4 bulk and ZrSiO_4 coating was performed under the conditions of 1.013×105 Pa, 90%H_2O/10%O_2, 1300 ℃, and low gas velocity. Results show that some pores appear on the surface of the ZrSiO_4 bulk. The main crystal phase is ZrO_2 and the weight loss of ZrSiO_4 bulk is only 0.236 mg/cm^2 after corrosion. The ZrSiO_4 coating peels off from the substrate after 109 h. The number and intensity of diffraction peaks of ZrO_2 in the coating increase, and the major crystal phase of the coating is still ZrSiO_4. A porous microstructure accompanied with cracks is observed on the surface of ZrSiO_4 coating after corrosion.展开更多
基金financial supported by the National Natural Science Foundation of China(Nos.51672064 and 51972089)。
文摘Yttrium aluminum perovskite(YAl O3)is a promising candidate material for environmental barrier coatings(EBCs)to protect Al2 O3 f/Al2 O3 ceramic matrix composites(CMCs)from the corrosion of high-temperature water vapor in combustion environments.Nevertheless,the relatively high thermal conductivity is a notable drawback of YAl O3 for environmental barrier coating application.Herein,in order to make REAl O3 more thermal insulating,a novel high-entropy rare-earth aluminate ceramic(Y0.2Nd0.2Sm0.2Eu0.2Er0.2)AlO3 was designed and synthesized.The as-prepared(Y0.2Nd0.2Sm0.2Eu0.2Er0.2)AlO3 ceramic possesses close thermal expansion coefficient(9.02×10-6/oC measured from room temperature to 1200℃)to that of Al2 O3.The thermal conductivity of(Y0.2Nd0.2Sm0.2Eu0.2Er0.2)AlO3 at room temperature is 4.1 W·m-1K-1,which is almost one third of the value of YAl O3.Furthermore,to effectively prevent the penetration of water vapor from possible pores/cracks of coating layer,which are often observed in T/EBCs,a tri-layer EBC system REAl O3/RE3 Al5 O12/(Al2 O3 f/Al2 O3 CMCs)is designed.Close thermal expansion coefficient to Al2 O3 and low thermal conductivity of(Y0.2Nd0.2Sm0.2Eu0.2Er0.2)AlO3,as well as the formation of dense garnet layer at(Y0.2Nd0.2Sm0.2Eu0.2Er0.2)AlO3/Al2 O3 interface,indicate that this new type of high-entropy ceramic is suitable as a candidate environmental barrier coating material for Al2 O3 f/Al2 O3 CMCs.
基金supported by the National Natural Science Foundation of China under Grant No.51772027
文摘ZrSiO_4 bulk was prepared by pressureless sintering process and ZrSiO_4 coating was deposited on the SiC f/Si C substrate using air plasma method. The microstructures of ZrSiO_4 bulk and ZrSiO_4 coating are both dense. A preliminary study of a water vapor corrosion test for ZrSiO_4 bulk and ZrSiO_4 coating was performed under the conditions of 1.013×105 Pa, 90%H_2O/10%O_2, 1300 ℃, and low gas velocity. Results show that some pores appear on the surface of the ZrSiO_4 bulk. The main crystal phase is ZrO_2 and the weight loss of ZrSiO_4 bulk is only 0.236 mg/cm^2 after corrosion. The ZrSiO_4 coating peels off from the substrate after 109 h. The number and intensity of diffraction peaks of ZrO_2 in the coating increase, and the major crystal phase of the coating is still ZrSiO_4. A porous microstructure accompanied with cracks is observed on the surface of ZrSiO_4 coating after corrosion.
