Preparation and Characterization of alpha'-Sialon Ceramics

摘要

Investigations into the interrelationships among the chemical compositions,powder characteristics, sintering parameters, microstructure and properties of yttrium-alpha'-sialon ceramics, and the achievement of fully dense alpha'-sialon ceramics using optimized gas pressure sintering parameters are reported. Composite alpha'+beta'-sialon ceramics are included. Gas pressure sintering was used to achieve full densification of alpha'-sialon ceramics with a fine grained microstructure and the process was optimized by statistical evaluation. Microstructure analysis using X ray diffraction, neutron powder diffraction, optical microscopy, scanning electron microscopy, and transmission electron microscopy are presented. The evaluation of both mechanical properties, such as Vickers hardness, fracture toughness, biaxial bending strength and wear resistance, and oxidation resistance of alpha'-sialon ceramics at various oxidation conditions are reported. Results observed indicate that the increasing amount of oxide additives leads to some negative effects in the microstructure and consequently in the properties of the final products. The composite alpha'+ beta'-sialons has very promising mechanical properties and an oxidation resistance comparable with both monolithic alpha' and beta'-sialon ceramics.