Oxidation treatments for SiC particles used as reinforcement in aluminium matrix composites

The present research is centred on the application of oxidation treatments to SiC particles to improve the casting processability of Al-SiC composites by means of a chemical interface control. If a continuous SiO2 layer is generated on the particle surface, the reinforcement particles can be incorporated in a molten aluminium matrix, and the degrading reaction of Al4C3 formation is replaced by other interfacial reactions which improve wettability, avoid particle consumption and increase interface strength. This work presents an optimisation study of the oxidation treatment conditions for SiC particles to obtain continuous adherent coatings which act as active barriers. The influence of particle sizes and treatment temperatures on the oxidation kinetics and barrier structure were evaluated. The capability of the protective barriers developed in the interfacial control was analysed by means of reactivity tests with molten aluminium, in comparison with unprotected particles. Both effects on local reactivity and mechanical interface properties were studied. (C) 2004 Elsevier Ltd. All rights reserved.