Preparation and pattern recognition of O′-sialon by reduction–nitridation from coal gangue

The phase composition and microstructure of O′-sialon prepared from Chinese coal gangue have been studied. The use of Si powder is more effective than that of activated carbon or mainly carbon with a little silicon for reduction–nitridation. For specimens with 40% Si addition, more than 80% of O′-sialon may be obtained when nitrided at 1500 °C. The formed O′-sialon was characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The parameters for O′-Sialon preparation are optimized by computer pattern recognition program based on principal component analysis, the target parameter optimum regions with higher relative content of O′-Sialon was indicated by this way.