The volume density and mechanical strength are increased by impregnating the asphalt into the electrode pores to eliminate the pores, which reduces the resistivity.
Graphite electrodes are usually impregnated with coal tar pitch when baking semi-finished products, and then graphitized after impregnation. Thus, the bulk density can
be increased from 1.55 g / cm ³ Increased to 1.65g/cm ³, The porosity also decreased from 25-32% to 22-25%, and the compressive strength also increased by 100kg / cm ³。
The coal tar pitch of common impregnating agent requires that the water content is not more than 0.2%, the ash content is not more than 0.5%, the volatile content is
60-70%, and the softening point is between 75 ℃ and 90 ℃.