基于保护平面热源法的防隔热材料热物性测量

Thermophysical Property Measurement of Thermal Protective Material by Guarded Plane Source Method

提出了一种可同时测量材料热导率、热扩散率并同步估计接触热阻影响的保护平面热源法.首先,建立了能够评估接触热阻影响的热传导模型;其次,设计并搭建了用于实验验证的热物性测量装置,其中的核心部件测温探头采用了附着于陶瓷基底的刻蚀双螺旋铂金属丝结构,可同时实现加热及测温;最后,利用此装置对2种标准材料在常温及1,200,℃下的热物性进行了测量.测量结果表明,由于该方法能同时考虑接触热阻的影响,热导率及热扩散率的测量误差可分别控制在5%及10%以内.因此,考虑实际存在的接触热阻可以提高热物性测量的准确度;接触热阻会受试样与探头接触紧密程度的影响,并最终对热物性测量准确度造成影响,良性接触是保证热物性高精度测量的关键.

In this paper, a guarded plane source method for contemporary measuring thermal conductivity and thermal diffusivity and estimating thermal contact resistance in step was presented. A heat propagation model which can estimate thermal contact resistance influence was first investigated and established. The special devices to be used in the experimental procedure were then designed and built, of which the key probe comprises a flat sensor with a continuous double spiral of electrically-conducting platinum metal etched out of thin foil and attached to a ceramic thin substate, acting as both heater and temperature sensors. Ambient temperature tests from room temperature up to 1 200 ℃ on two standardized materials were performed. The results show that the proposed method has a good capacity of determining both thermophysical properties and thermal contact resistance, with the measurement errors controlled within 5% and 10% for thermal conductivity and thermal diffusivity, respectively. So, given that thermal contact resistance can greatly increase the accuracy in measuring thermal physical properties while increasing contact resistance will decrease measurement precision, the sample holder has to be carefully designed to ensure optimal contact between sample and probe during measurement.