Preparation and properties of in situ TiC/corundum–mullite electrically conductive ceramic

Abstract

AbstractIn situ TiC/corundum–mullite electrically conductive ceramics were prepared by carbon‐bed sintering method using bauxite, clay and Ti3SiC2 powders as raw materials. The phase composition, microstructure, shrinkage, apparent porosity, bulk density, compressive strength, and resistivity of samples were investigated. The X‐ray diffraction results indicate that the TiC is completely generated by desilicidation reaction of the Ti3SiC2 at 1 300°C. When the sintering temperature is 1 300°C and Ti3SiC2 powder addition is 22 wt.%, the properties of the sample are optimum, with a longitudinal shrinkage of 2.04%, a radial shrinkage of 2.56%, an apparent porosity of 19.01%, a bulk density of 2.53 g/cm3, a compressive strength of 181 MPa, and a resistivity of 267 Ω·cm. The electrically conductive phase TiC is connected into a complete electrically conductive network. The shrinkages of samples decrease with increasing sintering temperature, which indicates that the samples expand due to secondary mullitization. The continuous electrically conductive network of TiC is destroyed. As the Ti3SiC2 powder addition increases from 14 to 20 wt.%, the resistivity of the samples decreases significantly, but the further increase in the Ti3SiC2 powder addition has no significant effect on the resistivity.