Preparation of SiCf/SiC composites by the slip infiltration and transient eutectoid (SITE) process

A novel ceramic processing route “SITE”, composed of ceramic slip infiltration in a SiC-fibre preform and the low-temperature sintering of a SiC-based matrix using a transient eutectoid, has been introduced as an optional way of producing low-activation, SiC-based, ceramic-matrix composites for fusion applications. The matrix material’s composition was developed on the basis of sintering studies using submicron and nanosized SiC powders and various low-activation precursors for the transient eutectoid secondary phase. Three different compositions of the secondary phase were investigated: SiO2–Y2O3–P2O5, SiO2–MgO–P2O5 and SiO2–Al2O3–P2O5. The last of these resulted in the most promising material, which was obtained by sintering in controlled atmospheres at temperatures up to 1400 °C, where the SiC-fibres were prevented from losing their original properties. The matrix-material samples were characterised for their phase compositions. The SiC-fibre preform was infiltrated with the matrix material by using electrophoretic deposition. A stable and well-dispersed aqueous suspension enabled the efficient infiltration and preparation of a SiCf/SiC composite with a relatively high density. The simple and rapid SITE processing technique appears to offer a viable, low-cost alternative to the methods presently used to produce low-activation SiCf/SiC composites.