Preparation and properties of SiAlON ceramics by gel casting and pressureless sintering

Abstract

This study employed a low-toxicity N, N-dimethylacrylamide/N, N-methylene acrylamide (DMAA /MBAM) gel system to near net shape SiAlON ceramics from aqueous slurries with a solid loading of 40 wt.% Si3N4, Al2O3, Y2O3, AlN, and Ce2O3 powder mixtures. The green bodies were sintered by one- and three-step pressureless sintering. Results showed that green bodies had a homogeneous microstructure with a high density of 1,9 g/cm3 and high flexural strength of 28,6 Mpa. Equiaxed α-SiAlON was prepared by one-step pressureless sintering, whereas β-Si4Al2O2N6 with an elongated morphology was fabricated by three-step pressureless sintering. Therefore, a lowtemperature heat preservation stage reduces the nucleation rate, which is favorable for the development of elongated β-SiAlON grains.

Keywords

• SiAlON ceramics, gelcasting, pressureless sintering, microstructure, mechanical properties