Mechanical Properties of Porous-Matrix Ceramic Composites

The use of porous matrices to enable damage tolerance in ceramic composites has emerged as a new paradigm in high performance materials. This paradigm obviates the need for fiber coatings for the purpose of crack deflection, thereby providing opportunities for lower cost manufacturing relative to that of conventional coated-fiber systems. Furthermore, upon selection of all-oxide constituents, the prospect for meeting the long-term durability requirements of high-temperature components for future gas turbine engine technologies becomes realizable. This article reviews the mechanical properties of this class of all-oxide composite. The properties of interest include the in-plane strength and notch-sensitivity subject to both fiber- and matrix-dominated loadings, and interlaminar strength. Special emphasis is placed on the role of the porous matrix in each of these properties. Finally, the issue of the stability of the matrix microstructure following prolonged exposure at elevated temperature is addressed and its role in maintaining desirable mechanical properties is demonstrated.