Preparation of β-Sialon/Ti(C, N) Composite Materials from Low-Grade Bauxite and Ilmenite

摘要

β-sialon/Ti (C, N) composite powders were synthesized via a carbothermal reduction nitridation (CRN) method using low-grade bauxite and ilmenite as starting materials and coke as the reducing agent. Then the composites were sintered from the β-sialon/Ti(C, N) composite powders in nitrogen atmosphere with Y_2O_3 and Al_2O_3 as sintering aids. In this study, long columnar β-sialon decomposed completely to short columnar AIN-polytypoids and lamellar AIN when sintered at 1500 °C. With an increase in sintering temperature, the volume density of the composites synthesized from low-grade bauxite decreased. The bending strength was 23.3 MPa when sintered at 1600°C, and the apparent porosity reached maximum value of 57.2% when sintered at 1500 °C. When the sintering temperatures increased, the volume density of the composites sintered from low-grade bauxite and ilmenite increased. The bending strength reached 25.0 MPa when sintered at 1600°C, and the apparent porosity reached the maximum value of 59.7% when sintered at 1500 °C.