The yttria-stabilized zirconia(YSZ)is a famous thermal barrier coating material to protect hot-end components of an engine.As a characteristic feature of the YSZ,the surface roughness shall play an important role in t...The yttria-stabilized zirconia(YSZ)is a famous thermal barrier coating material to protect hot-end components of an engine.As a characteristic feature of the YSZ,the surface roughness shall play an important role in the interface thermal conductance between the YSZ and gas,considering that the gas is typically at an extremely high temperature.We investigate the effect of the surface roughness on the thermal conductance of the YSZ-gas interface with surface roughness described by nanoscale pores on the surface of the YSZ.We reveal two competitive mechanisms related to the microstructure of the pore,i.e.,the actual contact area effect and the confinement effect.The increase of the pore depth will enlarge the actual contact area between the YSZ and gas,leading to enhancement of the solid-gas interface thermal conductance.In contrast to the positive actual contact area effect,the geometry-induced confinement effect greatly reduces the interface thermal conductance.These findings shall offer some fundamental understandings for the microscopic mechanisms of the YSZ-gas interface thermal conductance.展开更多
In order to study the thermal insulation and cooling properties of thermal barrier coatings of a flame baffle,several ZrO2 thermal barrier coatings with different thicknesses were prepared on the surface of aluminium-...In order to study the thermal insulation and cooling properties of thermal barrier coatings of a flame baffle,several ZrO2 thermal barrier coatings with different thicknesses were prepared on the surface of aluminium-alloy flame-baffle samples by plasma spraying.The relations between temperature and time of these samples were tested when they were heated by combustion flame.The relations between temperature of the coatings and the sample bodies and time were also tested when the samples at high temperatures were cooled by water.The experimental results indicated that ① the thicker the thermal barrier coatings,the better the thermal insulation effect of the thermal barrier;② the higher the temperature,the more significant of the thermal insulation of the thermal barrier.Also,in the case of water-cooling,the cooling rate of the coatings was greatly subject to the plate body and the cooling rate of coatings below 1.0mm was equivalent to that of the plate body.展开更多
Residual thermal stress in the system is a serious problem that affects the application of tritium permeation barrier coatings in fusion reactors. The stress not only determines the adhesion between coating and substr...Residual thermal stress in the system is a serious problem that affects the application of tritium permeation barrier coatings in fusion reactors. The stress not only determines the adhesion between coating and substrate, but also changes the properties of the material. In this study,finite element analysis was used to investigate the relationship between the residual thermal stress and the mechanical properties of Al_2O_3 tritium penetration barrier systems. Moreover, the residual thermal stress influenced by factors such as different substrates, temperature, and substrate roughness was also analyzed. The calculation showed that the hardness and elastic modulus increased with increasing compressive stress. However, the hardness and elastic modulus decreased with increasing tensile stress. The systems composed of Al_2O_3 coatings and different substrates exhibited different trends in mechanical properties. As the temperature increased, the hardness and the elastic modulus increased in an Al_2O_3/316 L stainless steel system; the trend was opposite in an Al_2O_3/Si system.Apart from this, the roughness of the substrate surface in the system could magnify the change in hardness and elastic modulus of the coating. Results showed that all these factors led to variation in the mechanical properties of Al_2O_3 tritium permeation barrier systems. Thus, thedetailed reasons for the changes in mechanical properties of these materials need to be analyzed.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11822206 and 12072182)the Innovation Program of the Shanghai Municipal Education Commission(Grant No.2017-01-07-00-09-E00019)+1 种基金the Key Research Project of Zhejiang Laboratorythe National Supercomputing Center in Zhengzhou(Grant No.2021PE0AC02)
文摘The yttria-stabilized zirconia(YSZ)is a famous thermal barrier coating material to protect hot-end components of an engine.As a characteristic feature of the YSZ,the surface roughness shall play an important role in the interface thermal conductance between the YSZ and gas,considering that the gas is typically at an extremely high temperature.We investigate the effect of the surface roughness on the thermal conductance of the YSZ-gas interface with surface roughness described by nanoscale pores on the surface of the YSZ.We reveal two competitive mechanisms related to the microstructure of the pore,i.e.,the actual contact area effect and the confinement effect.The increase of the pore depth will enlarge the actual contact area between the YSZ and gas,leading to enhancement of the solid-gas interface thermal conductance.In contrast to the positive actual contact area effect,the geometry-induced confinement effect greatly reduces the interface thermal conductance.These findings shall offer some fundamental understandings for the microscopic mechanisms of the YSZ-gas interface thermal conductance.
文摘In order to study the thermal insulation and cooling properties of thermal barrier coatings of a flame baffle,several ZrO2 thermal barrier coatings with different thicknesses were prepared on the surface of aluminium-alloy flame-baffle samples by plasma spraying.The relations between temperature and time of these samples were tested when they were heated by combustion flame.The relations between temperature of the coatings and the sample bodies and time were also tested when the samples at high temperatures were cooled by water.The experimental results indicated that ① the thicker the thermal barrier coatings,the better the thermal insulation effect of the thermal barrier;② the higher the temperature,the more significant of the thermal insulation of the thermal barrier.Also,in the case of water-cooling,the cooling rate of the coatings was greatly subject to the plate body and the cooling rate of coatings below 1.0mm was equivalent to that of the plate body.
文摘Residual thermal stress in the system is a serious problem that affects the application of tritium permeation barrier coatings in fusion reactors. The stress not only determines the adhesion between coating and substrate, but also changes the properties of the material. In this study,finite element analysis was used to investigate the relationship between the residual thermal stress and the mechanical properties of Al_2O_3 tritium penetration barrier systems. Moreover, the residual thermal stress influenced by factors such as different substrates, temperature, and substrate roughness was also analyzed. The calculation showed that the hardness and elastic modulus increased with increasing compressive stress. However, the hardness and elastic modulus decreased with increasing tensile stress. The systems composed of Al_2O_3 coatings and different substrates exhibited different trends in mechanical properties. As the temperature increased, the hardness and the elastic modulus increased in an Al_2O_3/316 L stainless steel system; the trend was opposite in an Al_2O_3/Si system.Apart from this, the roughness of the substrate surface in the system could magnify the change in hardness and elastic modulus of the coating. Results showed that all these factors led to variation in the mechanical properties of Al_2O_3 tritium permeation barrier systems. Thus, thedetailed reasons for the changes in mechanical properties of these materials need to be analyzed.
