Thermal conductivity and density of graphite powder
For the same type of graphite, the thermal conductivity increases with increasing density, and Figure 11 shows the relation between the density of HDFG and the density of the same graphite.The heat treatment temperature of polycrystalline graphite is mostly made by roasting the semifinished material by high temperature heat treatment. The higher the heat treatment temperature is, the more perfect the crystallite growth is, the La increases, and the thermal conductivity also increases. With calcined petroleum coke and coal tar pitch, roasting sticks made of extrusion, after different heat treatment (HTT), the value of La are shown in Table 4. The axial thermal conductivity will change with temperature is shown in figure 12. The reciprocal of thermal conductivity 1/ lambda is called thermal resistance. At different temperatures, the relationship between the axial thermal resistance of graphite is shown in Figure 13 and l/La / 1/.
In the formula, P is porosity, and lambda 0 is the thermal conductivity without hole (P=0). This formula is of historic significance. For graphite, the pores are not spherical or more unequal, but of course they do not apply. But it shows that the larger the porosity (the smaller the density), the smaller the thermal conductivity. This qualitative conclusion is correct.
In the formula, P is porosity, and lambda 0 is the thermal conductivity without hole (P=0). This formula is of historic significance. For graphite, the pores are not spherical or more unequal, but of course they do not apply. But it shows that the larger the porosity (the smaller the density), the smaller the thermal conductivity. This qualitative conclusion is correct. An extruded graphite core with different impregnation treatments
