In situ synthesis of Al2O3–ZrO2–SiCw ceramic matrix composites by carbothermal reduction of natural silicates

In situ formations of Al2O3+ZrO2+SiCW ternary composite powders have been obtained by carbothermal reduction of a mixture of Sillimanite, Kaolin and Zircon using two different carbon sources. Products formed were mixtures of alumina and zirconia along with silicon carbide in the form of whiskers. The effects of composition of the reactants, the role of fineness of the starting precursors and the nature of the carbon source on the final product powder obtained are presented. XRD and SEM analyses indicate complete reaction of the precursors to yield Al2O3+ZrO2+SiCW as product powders, with the SiC having whisker morphology. It is also seen that zirconia could be stabilised to some extent in the tetragonal form without any stabilising agent by tailoring the starting materials and their composition.