Preparation and Mechanical Properties of High-level Radial Textured SiAlON Ceramics

Radial textured SiAlON ceramics were prepared from sinter-forging ring-shaped SiAlON ceramic green bodies at 1750 ℃. The effects of Ni/Co (0–2.25 wt.%) additives on phase composition, texture degree, microstructure and mechanical properties of theh textured SiAlON ceramics were studied. On the section parallel to the grain orientation (RS, Radial Section), the orientation factor increased from 0.38 to 0.74 in the SiAlON ceramics due to the introduction of 2.25 wt.% Ni/Co. The radial texture microstructure was formed after sinter-forging. On the section perpendicular to the grain orientation direction (TS, Tangential Section), the grains exhibited equiaxed microstructure, while on the RS plane, the grains with rod-like microstructure are aligned in the same direction. The hardness of RS plane for the textured SiAlON ceramics is higher than that of TS plane, while the hardness decreases with increasing content of additives. The fracture toughness increases from (6.93±0.31) MPa·m^1/2 to (7.52±0.28) MPa·m^1/2 as the Ni/Co additives content increases from 0 to 2.25 wt.% in the direction perpendicular to the grain orientation of the RS plane.