Research And Measurement Of The Thermal Conduction Properties Of Graphene Powder For Micro-nano Scale

Graphene,a new carbon material,has excellent thermal conductivity.It is significant to measure the conduction thermal physical properties effectively.Due to the small size of graphene powder,the traditional methods based on Fourier law for thermal property measurement can not be used,and the research on the thermal transport properties of graphene powder is still defective.In addition,there are some limitations in the determination of the in-plane thermal conductivity of the powder material.In this paper,the in-plane thermal diffusivity of graphene powder is measured by transient electro-thermal technique and the corresponding intrinsic thermal conductivity is derived,which can avoid the limitation about the thickness.Using the thermal conductivity instrument（based on the modified transient plane source method）,we determine the thermal conductivity perpendicular to in-plane of graphene powder.The effect of moisture content,density and preheating temperature on the thermal conductivity of graphene powder is analyzed,and the corresponding thermal conduction mechanism is revealed.The graphene powder with a density of 0.24 g/cm³ is made up of five-six layers graphene.The range of the in-plane thermal diffusivity of graphene powder is identified from 0.86×10^-5-1.52×10^-5 m² s^-1 measured by the TET technique.Accordingly,the corresponding intrinsic thermal conductivity is 13.5–23.8 W/（m·K）.And the thermal conductivity perpendicular to in-plane of graphene powder is determined at 18.8W/（m·K）based on the modified transient plane source method.The influence of moisture content on the thermal conductivity of graphene powder is studied using the thermal conductivity instrument.The results show that the thermal conductivity of graphene powder is increased obviously with the increased moisture content.When the moisture content of graphene powder is increased up to 92.3%,the thermal conductivity of graphene powder is increased by 60%.The thermal conductivity of graphene powder under different density is measured by thermal conductivity instrument,and it is found that the thermal conductivity is proportional to the density.When the density of graphene powder is increased from0.02g/cm³ to 0.22g/cm³,the thermal conductivity is increased by 8.09%.In order to study the effect of preheating temperature on the thermal conductivity of graphene powder,we put the graphene powder samples with a constant density of0.045 g/cm³ in the temperature conditions of 50℃-300 ℃,respectively.The results show that the thermal conductivities of the graphene powder,which are cooled to room temperature after the treatment with different preheating temperature（50℃-300℃）,are not affected by the preheating temperature.