Titanium carbide/aluminum composites by melt infiltration.

摘要

Metal/ceramic composites have attracted considerable attention in the last 20 years, primarily due to the flexibility they offer when designing material with tailored properties. Melt infiltration is a popular fabricating method for such composites, as it allows the production of near-net shape components with high ceramic content. Capillaric melt infiltration is a simpler process since the liquid penetrates the preform under the action of a capillary pressure. This work deals with the fabrication and evaluation of a TiC/Al composite produced by melt infiltration. Pre-sintered preforms, having different void fraction and pore size, where infiltrated with pure Al, in an argon atmosphere, at various temperatures. The infiltration was carried out using the contact and the capillary dip methods to study the mechanical properties and infiltration behaviour, respectively.;The material exhibited a wide range of properties, depending on the ceramic content. Optimum tensile strengths of up to 480MPa were obtained for composites containing between 67 and 75% TiC, and infiltrated at 1050-1200;An experimental set-up was designed to measure the rate of infiltration by continually monitoring the weight changes of the preform as a result of the penetration of Al. Infiltration profiles were generated as a function of pore size, pore volume and temperature. At low temperatures, an incubation period was evident as a result of the transient contact angle between the two phases. Moreover, infiltration was inhibited at lower pore volume fraction. Finally, the Activation energy for the system increased from 90 to 450kJ/mol, with increasing pore size, suggesting a transition from a diffusion controlled process to one activated by a surface reaction for larger pore sizes.