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

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 1200,℃ on two standardized materia ls 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.