SiC陶瓷的低温力学和热学性能研究

Research of Mechanical and Thermal Properties of SiC at Cryogenic Temperatures

通过对SiC陶瓷在室温(293K)至低温(77K)下力学和热学性能的研究,分析了其力学、热学性能的变化规律和影响因素,并探讨其作为低温材料的应用前景。实验发现,SiC陶瓷在低温下强度升高,韧性变化却很小。SiC陶瓷热导率在90至360K区间变化幅度较小,而在90K以下则迅速降低,热膨胀曲线随温度接近线性变化,拟合得到其在125~290K温度区间内的平均热膨胀系数约为1.15×10-6,小于室温下一般常压烧结SiC陶瓷的热膨胀系数。

The influence of temperature between R.T. (293 K) and liquid nitrogen (77 K) on mechanical and thermal properties of SiC have been investigated and the prospect of SiC used as adequate materials in cryogenic engineering has been discussed as well. It is observed that the flexural strength of SiC at cryogenic temperatures is increased while the fracture toughness keeps almost unchanged. The conductivity exhibits slight change between 90 and 360 K but dramatical decrease below 90 K. The average thermal coefficient between 125 and 290 K is 1.15×10-6 by fitting from the measurement of thermal expansion which shows a linear variation along with temperature.