SINTERING A MIXTURE OF POWDERS IN THE Al2O3-SiO2-beta-SiAlON-TiC-Dy2O3 SYSTEM BY THE SPARK-PLASMA METHOD WITH HIGH COMPACTION LOADING

摘要

The effect of the addition of 2 and 5 mol.% Dy2O3 during spark-plasma sintering at a compaction loading of 60 MPa in the range of 1200 - 1600 degrees C on phase composition, microstructure, relative density, open porosity, linear shrinkage, physicomechanical properties, and linear correlation of the elastic modulus and fracture toughness of mullite-sialon-TiC samples is shown. The synthesized powders of sialon and TiC are characterized by corresponding intensive crystallization. The increase in the content of Dy2O3 from 2 to 5 mol.% in the sintered composition to produce beta-SiAlON/TiC = 70/30 mol.% promotes intensive mullitization, active growth of sialon and less intensive growth of TiC in the range of 1200-1600 degrees CC, and also leads to the formation of less densely sintered crystalline microstructures in the sample, containing round crystalline TiO2 particles, pores and glassy phase at the boundaries of the regions in mullite-sialon-TiC solid solution composites at 1500 degrees CC. Asample containing 5 mol.% Dy2O3 has lower values of relative density, linear shrinkage, physical and mechanical properties in the range of 1200 - 1600 degrees CC, lower crack resistance with the formation of microcracks at 1500 degrees CC and a slightly larger linear correlation of the elastic modulus and impact toughness in the range of 1200 - 1600 degrees C.