Synthetic resin-bonded transition-metal carbide–carbon hetero-modulus ceramics

Hetero-modulus ceramics (HMC) present an opportunity to combine a ceramic matrix having high Young's modulus with inclusions of a material having a considerably lower value of Young's modulus. The manufacturing method for the powder transition-metal carbide–graphite HMC with synthetic binder was studied. A statistical model for the cured-pressed carbide–carbon powder composition with resin binder was developed employing the statistical fractional factorial experimental design with the 25–2 matrix type for several processing parameters. During the subsequent carbonisation of these compacts, the mutual influence between the carbide phase and the phenol–formaldehyde binder leads to the specific transformations in resin-bonded HMC. The pyrolysis reactions in the resin begin at lower temperatures and the products oxidise carbides with the formation of metal oxycarbides and oxides, so the behaviour of HMC depends strongly on the carbide content. The mass gain of carbonised compacts is compensated for by their swelling, so the bulk density in the wide range of contents does not vary after carbonisation. Possessing lower strength, the resin-bonded HMC have better thermal shock/fatigue resistance than materials hot-pressed at high temperatures.