Liquid-Phase Densification of Titanium Carbide - Nickel Composites

摘要

Liquid phase sintering of titanium carbide nickel composites was studied by high temperature scanning electron microscopy. The sintering kinetics were seen to be strongly dependent upon additions of free carbon to the system. Densification was progressively decreased with increasing carbon additions. These results are explained on the basis of changes in the eutectic reaction in the system, reduced solubility of titanium carbide in liquid phase, and decreased wetting of the solid by the liquid. The influence of hydrogen heat treatment of particle compacts prior to sintering was also investigated. This processing resulted in the reduction of densification rates and elevated temperatures of liquid phase formation. Wetting experiments on hydrogen treated materials showed a time dependent contact angle. These results are discussed based on wetting theory and reactions predicted by the equilibrium ternary diagram.