The improvement in oxidation resistance of magnesia-carbon refractory bricks by Al4SiC4

Oxidation of carbon is the main problem in magnesia-carbon refractory bricks. Al4SiC4 powder is an excellent antioxidant which has obvious practical significance. It was prepared by vacuum sintering at 1700 degrees C in vacuum sintering furnace. The effect of Al4SiC4 on the oxidation resistance of magnesia-carbon bricks were investigated at 1500 degrees C. The thickness of decarburized layer of bricks was measured and the oxidized situation of the bricks was examined by XRD, SEM and EDAS. The decarburization layer became thin with adding Al4SiC4 powder. Magnesium alumina spinel (MgAl2O4) was determined to be present by characterization studies on Al4SiC4 added specimens and phase evolution of MgAl2O4 spinel formation were investigated by XRD. The optical microscope and EDAS indicated that the spinel diminished the open pores owing to its volume expansion and formed a protective layer on the surface. The results suggested that the spinel had an excellent effect on the oxidation resistance of bricks. In addition, compared with adding other aluminum-containing antioxidants, the specimens added Al4SiC4 had better stability from high temperature to room temperature.