OPTIMIZATION OF ALUMINA - SILICON-CARBIDE DISPERSIONS AND THE FABRICATION OF NANOCOMPOSITE CERAMIC MATERIALS

Ceramic nanocomposite materials have been reported to have good mechanical properties. However, close control of the fabrication process must be maintained in order to achieve good dispersion of the secondary phase within the matrix which is essential if these good properties are to be obtained. To date, only powder processing in organic media has been reported. The processing conditions of alumina-silicon carbide nanocomposites have been investigated. Processing was carried out in aqueous and organic media. Optimisation of dispersion involved measurement of the zeta potential of alumina and silicon carbide aqueous slurries, selection of organic mixing media as well as the type and quantity of dispersing agent. Dense materials were obtained by hot pressing of the optimised powders. Microstructural analysis and mechanical property assessment have been carried out. A strength improvement of 30% was achieved by the addition of 5 vol% SiC to alumina.