亚微米级多孔绝热膜的纵向热导率的测试

THE MEASUREMENT OF LONGITUDINAL THERMAL CONDUCTIVITY OF SUB-MICROMETER POROUS THERMAL INSULATION FILMS

提出了采用调制热源，热沉边界条件下的超低频薄膜纵向热导率测试方法，结合金属薄膜的弱温度探测，使薄膜厚度方向的热导率测试进入到了亚微米量级．室温下 热导率采用了线性拟合外推法求得．实测的多孔 ＳｉＯ２薄膜热导率比致密的块体材料 低了 ３个量级，为 ０．００１Ｗ／ｍ·Ｋ．

Method is proposed to measure the lognitudinal thermal conductivity of thin film with a modulated heat source of ultra-low frequency under heat sink boundary condition. Combined with the measurement of weak temperature fluctuation by metal thin film resistance ,longitu-dinal thermal conductivity of the thin film with thickness of sub-micrometer magnitude can be measured. Linear regressive extrapolation method is used to obtain the thermal conductivi-ty under roon temperature. Measured thermal conductivity of porous silica thin films is lower than that of the bulk materials by three orders of magnitude and the value is 0. 001 W/m· K.