Thermal expansion coefficient of Y-alpha'-sialon

A sialon composite composed of Y-alpha'-sialon and beta'-sialon has been fabricated by hot pressing mixtures of Si3N4, Y2O3 and AIN powders. Thermal expansion coefficients of the Y-alpha'-sialon and beta'-sialon were determined by the high-temperature X-ray diffraction technique. The thermal expansion coefficient of Y-alpha'-sialon depended on the composition, being minimum at x = 0.3 in the formula Y-x(Si12-4.5x,Al4(.5x)) (O-1.5x,N16-1.5x). The coefficient of beta'-sialon increased with increasing lattice constant, that is, the z value in the formula Si6-zAlzOzN8-z. The thermal expansion coefficient of sialon composites determined by a differential dilatometer increased with increasing amount of Y-alpha'-sialon.