Physicomechanical properties of ultrahigh temperature heteromodulus ceramics based on group 4 transition metal carbides

Highly densified TiC, ZrC and HfC based ultrahigh temperature heteromodulus ceramics (HMC), containing 10-50 vol.-% of low modulus phase in the form of particulate graphite, were prepared by hot pressing at 2700°C and 12 MPa in argon atmosphere. The microstructure, elastic characteristics, flexural and compressive static strength, fracture toughness, impact resistance, hardness and thermal expansion were investigated and compared with those available in earlier works for clear understanding the composition-property correlations and anisotropy of this type of HMC composites. Different thermal shock resistant parameters for the HMC were calculated on the basis of obtained experimental data. A new principle of optimum materials design for the compositions in the refractory carbide-graphite systems is exemplified by the TiC-C HMC materials.