The effect of interfacial chemical reaction on the mechanical properties of Si3N4 whisker/Al2O3 composite

Si3N4 whisker/Al2O3 composites with various amounts of interfacial beta-SiAlON (beta'-phase, Si6-ZAlZOZN8-Z) were prepared while controlling the hot-pressing temperature and duration. X-ray diffraction analysis revealed that interfacial chemical reaction produced X-phase and beta-SiAlON with a Z-value of approximately 4. A model of the interfacial chemical reaction was proposed to explain the experimental results. The mechanical properties of the composites hot-pressed above 1600 degrees C were markedly different from those of the composites hot-pressed below 1600 degrees C, because X-phase at the whisker/matrix interface was liquefied during the hot-pressing above 1600 degrees C and vitrified X-phase seemed to increase interfacial bonding strength.