Fine grains and slow grain growth rate are beneficial to preventing the thermal stress-induced cracking and thermal conductivity increase of thermal barrier coatings.Inspired by the sluggish diffusion effect of high-e...Fine grains and slow grain growth rate are beneficial to preventing the thermal stress-induced cracking and thermal conductivity increase of thermal barrier coatings.Inspired by the sluggish diffusion effect of high-entropy materials,a novel high-entropy(HE)rare-earth zirconate solid solution(La0.2Ce0.2Nd0.2Sm0.2Eu0.2)2 Zr2 O7 was designed and successfully synthesized in this work.The as-synthesized(La0.2Ce0.2Nd0.2Sm0.2Eu0.2)2 Zr2 O7 is phase-pure with homogeneous rare-earth element distribution.The thermal conductivity of as-synthesized(La0.2Ce0.2Nd0.2Sm0.2Eu0.2)2 Zr2 O7 at room temperature is as low as 0.76 W m^-1 K^-1.Moreover,after being heated at 1500℃for 1-18 h,the average grain size of(La0.2Ce0.2Nd0.2Sm0.2Eu0.2)2 Zr2 O7 only increases from 1.69μm to 3.92μm,while the average grain size of La2Zr2O7 increases from 1.96μm to 8.89μm.Low thermal conductivity and sluggish grain growth rate indicate that high-entropy(La0.2Ce0.2Nd0.2Sm0.2Eu0.2)2Zr2O7 is suitable for application as a thermal barrier coating material and it may possess good thermal stress-induced cracking resistance.展开更多
Thermal barrier coating(TBC) materials play important roles in gas turbine engines to protect the Nibased super-alloys from the high temperature airflow damage. High melting point, ultra-low thermal conductivity, larg...Thermal barrier coating(TBC) materials play important roles in gas turbine engines to protect the Nibased super-alloys from the high temperature airflow damage. High melting point, ultra-low thermal conductivity, large thermal expansion coefficient, excellent damage tolerance and moderate mechanical properties are the main requirements of promising TBC materials. In order to improve the efficiency of jet and/or gas turbine engines, which is the key of improved thrust-to-weight ratios and the energysaving, significant efforts have been made on searching for enhanced TBC materials. Theoretically, density functional theory has been successfully used in scanning the structure and properties of materials, and at the same time predicting the mechanical and thermal properties of promising TBC materials for high and ultrahigh temperature applications, which are validated by subsequent experiments. Experimentally,doping and/or alloying are also widely applied to further decrease their thermal conductivities. Now, the strategy through combining theoretical calculations and experiments on searching for next generation thermal insulator materials is widely adopted. In this review, the common used techniques and the recent advantages on searching for promising TBC materials in both theory and experiments are summarized.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos.51672064 and U1435206)
文摘Fine grains and slow grain growth rate are beneficial to preventing the thermal stress-induced cracking and thermal conductivity increase of thermal barrier coatings.Inspired by the sluggish diffusion effect of high-entropy materials,a novel high-entropy(HE)rare-earth zirconate solid solution(La0.2Ce0.2Nd0.2Sm0.2Eu0.2)2 Zr2 O7 was designed and successfully synthesized in this work.The as-synthesized(La0.2Ce0.2Nd0.2Sm0.2Eu0.2)2 Zr2 O7 is phase-pure with homogeneous rare-earth element distribution.The thermal conductivity of as-synthesized(La0.2Ce0.2Nd0.2Sm0.2Eu0.2)2 Zr2 O7 at room temperature is as low as 0.76 W m^-1 K^-1.Moreover,after being heated at 1500℃for 1-18 h,the average grain size of(La0.2Ce0.2Nd0.2Sm0.2Eu0.2)2 Zr2 O7 only increases from 1.69μm to 3.92μm,while the average grain size of La2Zr2O7 increases from 1.96μm to 8.89μm.Low thermal conductivity and sluggish grain growth rate indicate that high-entropy(La0.2Ce0.2Nd0.2Sm0.2Eu0.2)2Zr2O7 is suitable for application as a thermal barrier coating material and it may possess good thermal stress-induced cracking resistance.
基金supported by the National Natural Science Foundation of China (No. 51602188)the Program for Professor of Special Appointment (Eastern Scholar)by Shanghai Municipal Education Commission (No. TP2015040)
文摘Thermal barrier coating(TBC) materials play important roles in gas turbine engines to protect the Nibased super-alloys from the high temperature airflow damage. High melting point, ultra-low thermal conductivity, large thermal expansion coefficient, excellent damage tolerance and moderate mechanical properties are the main requirements of promising TBC materials. In order to improve the efficiency of jet and/or gas turbine engines, which is the key of improved thrust-to-weight ratios and the energysaving, significant efforts have been made on searching for enhanced TBC materials. Theoretically, density functional theory has been successfully used in scanning the structure and properties of materials, and at the same time predicting the mechanical and thermal properties of promising TBC materials for high and ultrahigh temperature applications, which are validated by subsequent experiments. Experimentally,doping and/or alloying are also widely applied to further decrease their thermal conductivities. Now, the strategy through combining theoretical calculations and experiments on searching for next generation thermal insulator materials is widely adopted. In this review, the common used techniques and the recent advantages on searching for promising TBC materials in both theory and experiments are summarized.
