Preparation and characterization of SiAlON matrix composites reinforced with combustion synthesis rod-like SiAlON particles

SiAlON matrix composites were prepared from a precursor reaction mixture of α-Si3N4, AlN, Al2O3 and Y2O3 powders and reinforced with different proportions of elongated SiAlON particles obtained by combustion synthesis. Green cylindrical specimens were consolidated by slip casting from well dispersed suspensions. The dried samples were densified by hot pressing at 1650 and 1700 °C and then characterized for density, phase composition and microstructure. Hardness tests, fracture toughness by indentation and pin on disc wear, were also chosen to characterize their mechanical properties. The effects of the processing variables (sintering temperature, proportion of added rod-like SiAlON particles) on the microstructural features and on the mechanical properties were studied and a good correlation between them was found.