Materials such as alumina carbon bricks and carbon electrodes are sintered under a reducing atmosphere to prevent the oxidation of the carbon, which is present as a binder or aggregate. Some of the carbon components used can easily volatize during the sintering process, causing the products to become more porous after sintering. Figure 1 shows the appearance of an unimpregnated alumina carbon slide gate plate (hereafter referred to as SG plate), after four heats on a teeming ladle of middle carbon steel. It can be clearly seen that there has been significant damage. To overcome this damage and improve the service life, the products are generally impregnated with tar pitch or thermosetting resin~(1,2). Figure 2 shows the appearance of an impregnated SG plate after six heats. It is clear that the damage of the impregnated product was less than that of the unimpregnated product, shown in Fig. 1. In this comparison the impregnation extended the service
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