Sintering a Mixture of Powders in the Al2O3–SiO2–β-SiAlON–TiC–Dy2O3 System by the Spark-Plasma Method with High Compaction Loading

Abstract

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°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 β-SiAlON/TiC = 70/30 mol.% promotes intensive mullitization, active growth of sialon and less intensive growth of TiC in the range of 1200–1600°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°CC. Asample containing 5 mol.% Dy₂O₃ has lower values of relative density, linear shrinkage, physical and mechanical properties in the range of 1200 – 1600°CC, lower crack resistance with the formation of microcracks at 1500°CC and a slightly larger linear correlation of the elastic modulus and impact toughness in the range of 1200 – 1600°C.