Development Of Thermal Conductivity Tester For Composite

Thermal conductivity is an important parameter of thermal properties of materials.The existing thermal conductivity models are all based on single material.Attention is paid to the high thermal conductivity of grapheme,After graphene was discovered,Its high thermal conductivity has attracted much attention.The composite material formed by graphene and polymer materials is one of the research directions at present.However,there is no mature method to test the thermal conductivity of composites at home and abroad.In this paper,a thermal conductivity tester is designed and manufactured by using Transient Plane Source method.Graphene polypropylene composites were used as test objects,a test system suitable for thermal conductivity of composite materials is initially established.This subject adopts the relatively mature Transient Plane Source method as the basic principle of measurement,after analyzing and studying the influence of sample size,heating time and probe heat capacity and heat resistance,the basic formula of heat conduction is corrected appropriately.According to the technical requirements of Transient Plane Source method,a sensor is designed and manufactured,choose a high-precision regulated power supply to provide a constant current for the sensor,so that the power of the heat source is constant,select 7 1/2 bit digital voltmeter to collect voltage data,greatly improve the accuracy of micro voltage measurement,the electric bridge is made,and the sensor,the stabilized voltage supply and the digital voltmeter are integrated into the hardware system.The upper computer software controls the regulated power supply through the USB interface,and provides different heating power for the probe,by collecting the voltage of the digital voltmeter,the corresponding relationship between time and voltage is obtained,and the thermal conductivity of the material is finally obtained.Samples with known thermal conductivity are used to test the accuracy of the instrument.The results show that the accuracy of the instrument is within ±5%,which meets the design requirements.Several groups of tests on graphene-polypropylene composites have been completed.The results show that the tester can meet the testing requirements of the composites.