High-temperature hot-pressing of titanium carbide-graphite hetero-modulus ceramics

Abstract

Hetero-modulus ceramic-ceramic composite materials (HMC) present the combination of ceramic matrix with high Young's modulus and the inclusions of a dispersed phase with low Young's modulus. The densification of 60-100 vol% TiC-0-40 vol% C (graphite) HMC during hot-pressing of powder compositions at 2200-2400 °C and applied pressures of 8-16 MPa is studied. The general theory of bulk-viscous flow for porous body is developed to describe obtained experimental data. This relation as well as Kovalchenko's equation for the evolution of relative density for non-uniform deformation of porous body, incorporating different stages of creep, are used to determine the activation energy and the exponent constant of hot-pressing process, which values are 270 ± 30 kJ mol-1 and 3 ± 0.3, respectively. The obtained experimental data are discussed on the basis of extensive and detailed analysis of the previous studies on diffusion and diffusion-related phenomena in the Ti-C system. © 2006 Elsevier Ltd. All rights reserved.