Development of Nitride-Bonded SiC Refractories by MgO and Nanocomposite (MgO/SiC) Additives
Also effect of nanocomposite addition (SiC+MgO) which synthesized by magnesiothermal process on optimized samples were studied.
The laboratory samples were prepared by mixing, shaping and firing at 1450–1600 °C in control atmosphere furnace. Phase analysis, microscopic observation and mechanical evaluation were taken as criteria for microstructure evolution. Also industrial samples were prepared by optimizing of firing cycle and additives. Then phase analysis, mechanical properties and inhomogeneity on properties of bricks in different part of muffle were investigated.
Variation of mechanical properties by using MgO additive could be attributed the microstructure evolution and mainly to liquid phase formation and grain morphology. It was found that the additives, such as MgO could modify the microstructure and influence the mechanical behavior. To extend results to industrial scale, settlement of bricks and modify firing cycle have been investigated to solve inhomogeneity problems. Finally, addition of nanocomposite (MgO+SiC) to optimized samples increased hot modulus of
rupture (HMOR), which could be related to better sintering of matrix and formation of β-Si3N4.