Influence of additives on microstructural changes in nitride bonded SiC refractories

摘要

In this study the microstructural development of nitride-bonded SiC refractories is reported in presence of Al_2O_3 and MgO. The samples were prepared by mixing, shaping and firing at 1450-1600 deg C in a controlled atmosphere furnace. Phase analysis, microscopic observation and mechanical evaluation were taken as criteria for microstructural evolution. The strength of samples doped with alumina was initially increased and then decreased at higher amount of alumina additions while the addition of magnesia decreased the strength. These phenomena could be attributed to microstructural evolution and mainly to liquid phase formation and grain morphology. It was found that the additives such as Al_2O_3 and MgO could modify the microstructure and influence the mechanical behavior.