From a microscopic point of view, the heat conduction of graphite is due to the existence of heat-conducting carriers (conducting electrons and holes) and lattice vibration to conduct heat. The main factors affecting the resistivity of graphite are the scattering of grain boundaries and the concentration of carriers. Due to the existence of scattering, that is, the inhomogeneity of the medium, the free path of lattice vibration is reduced, that is, the thermal conductivity is reduced. Therefore, the thermal conductivity and electrical conductivity of graphite are basically inseparable.
From a macro perspective, the electrical and thermal conductivity of graphite is related to the properties of the raw material itself and the degree of graphitization. The higher the degree of graphitization-the smaller the electrical resistivity. Although there are many factors that characterize thermal shock resistance, the most important ones are thermal conductivity and linear expansion coefficient. The higher the graphitization degree-the higher the thermal conductivity, the linear expansion coefficient of graphite is much smaller than that of metal, and the higher the graphitization, the smaller the linear thermal expansion coefficient.
It can be seen that the electrical and thermal conductivity of graphite are proportional to a certain extent.
Since the electrode paste temperature tends to be close to graphitization during use, it can barely accept this characteristic of graphite.