Influence of uni and bi-modal SiC composition on mechanical properties and microstructure of reaction-bonded SiC ceramics

Abstract

Influence of SiC composition with different particle size on mechanical properties and microstructure of reaction-bonded SiC have been investigated using infiltration process of liquid Si. SiC specimens were prepared by reaction-bonding sintering at 1620°C in vacuum using different SiC–C composition. Reaction-bonded SiC specimens show dense with 3.0–3.05 gr/cm³ of density. SiC specimens with bi-modal SiC composition show a fine microstructure than those of uni-modal SiC composition. In addition, in the specimens with bi-modal SiC composition, the microstructure of the sample with use of fine SiC starting powders is finer rather than those of use of relatively coarse SiC starting powders. The flexural strength and fracture toughness of specimens with bi-modal SiC composition are higher than those of uni-modal SiC composition. The main fracture mode of specimens with a high strength is intergranular fracture.