What is the purpose of preheating carbon materials before impregnation?

Carbon materials such as carbon bricks, carbon blocks, graphite blocks, electrodes, etc. need to be impregnated during the production process. However, the green body (carbon billet) of the carbon material needs to be preheated before impregnation, so why should the carbon billet be preheated before impregnation?

Why do we need to preheat before impregnation??

Before impregnation, preheating treatment must be carried out on the impregnated carbon blank in the preheating furnace. The purpose is to: firstly, remove the gas adsorbed in the pores of the carbon blank; The bulk temperature is matched to the temperature of the impregnating bitumen. ?

Excluding the gas and moisture adsorbed in the pores of the carbon blank is to create conditions for the impregnating agent asphalt to enter the pores of the carbon blank smoothly. The carbon blank is fully preheated so that the temperature of the carbon blank body is higher than that of the impregnating agent pitch. Coal tar pitch maintains a good rheological state, which is conducive to improving the impregnation effect. Otherwise, when the liquid impregnating pitch encounters a lower temperature carbon billet, the temperature of the coal tar pitch will drop accordingly, resulting in an increase in the viscosity of the impregnating pitch, which will deteriorate its rheological properties and reduce the impregnation effect.