Effect of Silicon Addition on the Properties of Carbon Fiber Reinforced Mullite Based Castable Composites

The spalling and corrosion during the thermal cycles are the main causes of the damages observed in mullite based castable composites which are used in molten iron system. Using the toughening agents of carbon fibers and the anti-oxidant of silicon, mullite based castable composites were prepared by sintering in air atmosphere. The effect of the anti-oxidant of silicon on the various physical, microstructures and mechanical properties were studied. The addition of silicon has significantly improved the cold modules of rupture and the cold crushing strength after firing at 1100 °C, but has little effect on the samples fired at 1450 °C. The cold modules of rupture and the cold crushing strength can be increased by above 20% and 30% respectively when the samples were fired at 1100 °C. After being heated in the air, the most of carbon fibers still can be found in the samples fired at 1450 °C, but can not be found in the samples fired at 1100 °C.