Processing of damage-tolerant, oxidation-resistant ceramic matrix composites by a precursor infiltration and pyrolysis method

Damage-tolerant, continuous fiber ceramic matrix composites have been produced by an inexpensive method. According to this method, the space between the fibers is filled with a powder. The powder particles are heat treated to form a porous framework without shrinkage, which is then strengthened with an inorganic synthesized from a precursor. High particle packing densities can be achieved within the fiber preform provided that the particle-to-fiber diameter ratio is small. Filling the interstices with a powder increased the composite density and also limits the size of the crack-like voids within the matrix. In this review we describe the mechanical properties of partially dense materials produced from powders to show that a porous matrix can be strong. We demonstrate that the packing density of particles around fibers is highest when the particle-to-fiber diameter ratio is small. The kinetics and mechanical behavior of composite systems is summarized to demonstrate the requirements of damage-tolerant properties. An all-oxide ceramic matrix composite produced by this method is discussed.