摘要
采用激光脉冲法研究电子束物理气相沉积(EB-PVD)热障涂层热扩散系数的测定,对测定结果进行误差分析,研究试样热处理状况和遮挡层对热扩散系数的影响。结果表明:随着测试温度升高,EB-PVD热障涂层的热扩散系数先减小再增大,但在25～1200℃的测试温度范围内,变化幅度不大;在25℃时测试相对误差为4.6%,其余各温度的相对误差均小于1.5%;热扩散系数的变化与陶瓷材料的本征热导率随温度的变化以及涂层的微结构密切相关;热处理使涂层中产生了垂直于基体表面的微裂纹,部分热流通过微裂纹可直接到达涂层表面,导致热扩散系数增加;喷Au加石墨复合遮挡层的试样其热扩散系数比单一石墨遮挡层试样的低,主要是由于低发射率的Au减弱了辐射对传热的贡献。
Thermal diffusivity of electron beam-physical vapor deposition （EB-PVD） TBCs was measured using laser flash method. The error ranges were analyzed and the effects of heat treatment and shelter layers on the thermal diffusivity were investigated. The results show that thermal diffusivity of TBC decreases at the beginning and then increases with the elevation of testing temperature. But the extent of thermal diffusivity variation is not vast in the whole testing temperature range from 25 ℃ to 1 200 ℃. The maximum relative error is 4.6% at 25 ℃ and less than 1.5% at other testing temperature. The thermal diffusivity is closely related with the intrinsic properties change of ceramic with the increase of temperature and the microstructure of TBCs. Micro-cracks in heat-treated samples, which are perpendicular to the sample surface, permitted part of the heat flow to directly reach the surface of coatings and finally result in the increase of thermal diffusivity. Thermal diffusivity of sample with multi-shelter of Au and graphite is smaller than that of sample with single graphite shelter. The main reason for this phenomenon is that Au with low emission rate weakens the radiation effect on thermal conduction.
出处
《中南大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2008年第2期256-261,共6页
Journal of Central South University:Science and Technology
基金
国防基础科研项目(A1320061002)
