基于热辨识技术的硅基防热材料高温热导率测量

摘要

Silicon-based thermal protective materials are major compositions of the thermal protective system of hypersonic aircrafts.Unfortunately,the thermal conductivity of this kind of material is difficult to be measured at high temperature owing to the complex physical and chemical changes under high temperature conditions.As a result,the precise design of the thermal protective system of aircraft is greatly restrained.This study proposed a device for measuring the thermal conductivity of silicon-based thermal protective material at high temperature based on thermal conductivity identification method.Using the device and related method,the thermal conductivities of silicon-based thermal protective material was measured in a range from room temperature to 800 ℃.The obtained results were subsequendy extrapolated to other test conditions.Analysis results suggested tbat temperature calculation results were in good agreement with the test results,proving the reasonability and reliability of the high-temperature thermal conductivity of silicon-based thermal protective material obtained by the measuring device.The device and method proposed in this study synchronous measurement on thermal conductivities can be achieved at different temperatures with low cost and high efficiency.Thus they are of great reference value for the thermal conductivity measurement of other thermal protective materials at high temperature.%硅基防热材料是高超声速飞行器防热系统用重要材料之一,但由于硅基防热材料在高温条件下存在着复杂的物理化学变化,使得高温热导率的获取变得困难,这已成为飞行器防热系统精细化设计的主要制约瓶颈.基于热导率辨识方法,设计了一种能够实现硅基防热材料高温热导率测量的试验测量装置,对硅基防热材料在常温～800℃热导率进行了测量,并将测得的热导率外推应用到其他试验状态.结果表明,测得的硅基防热材料高温热导率合理可靠,具有很高的工程精度.该试验测量装置可实现不同温度下热导率的同步测量,测量成本低,效率高,这对其他防热材料的高温热导率测量具有重要的参考价值.