Processing of Oxide Composites with Three‐Dimensional Fiber Architectures

Fabrication of oxide fiber composites is accompanied by the development of drying cracks in the matrix following slurry infiltration. The cracks are a result of the inherent shrinkage in particle compacts during drying coupled with the mechanical constraints imposed on the matrix by the fibers. The effects are most pronounced in systems with three-dimensional fiber architectures. A mitigation strategy based on the addition of coarse matrix particles to the fine particulates has been devised and demonstrated. Among the various implementation strategies explored, the most effective involves combining the two particle types (coarse and fine) into a single slurry and coinfiltrating the slurry through sequential vibration- and vacuum-assisted processes. Regardless of the infiltration route, the SiC particles have no apparent detrimental effect on the fiber bundle properties. Additionally, they increase the through-thickness thermal diffusivity by 50%–100%.