Effect of controlled interfacial reaction on the microstructure and properties of the SiCp/Al composites prepared by pressureless infiltration

High volume fraction SiCp/Al composite is prepared by pressureless infiltration. In this paper, the effect of both the addition of Si to aluminum and passive oxidation of SiC to control SiC/Al interfacial reaction on the microstructure, thermal conductivity and coefficient of thermal expansion of infiltrated composite is investigated. TEM and X-ray results showed that severe interfacial reaction occurred between SiC reinforcement and Al matrix by the infiltration of the unoxidized SiCp preform by Al-8 wt% Mg at 1000 degrees C. And the reaction can be suppressed by the use of aluminum with 12 wt% Si addition or the SiC preform oxidized in air at 1200 degrees C for 3 h. The method of addition of Si to aluminum is more favorable to prepare composites with higher thermal conductivity, lower coefficient of thermal expansion and porosity as compared to the method of passive oxidation of SiC. The effect mechanism of both methods on the microstructure and thermal-physical properties is discussed. (C) 2007 Elsevier B.V. All rights reserved.