In-Situ Formation of Reinforcement Phases in Ultra-High- Temperature Ceramic Composites

Future-generation materials for use on space transportation vehicles require substantial improvements in material properties leading to increased reliability and safety, as well as intelligent design to allow for current materials to meet future needs. Ultra-high-temperature ceramics (UHTC), composed primarily of metal diborides, are candidate materials for sharp leading edges on hypersonic re-entry vehicles. NASA has demonstrated that it is possible to form high-aspect-ratio reinforcement phases in-situ during the processing step for both ceramic composites and UHTCs. Initial characterization of these systems has demonstrated that crack deflection along the matrix-reinforcement interface is observed yielding a system of improved toughness over the baseline system, leading to improved mechanical performance. The reinforced composites should therefore reduce the risk of catastrophic failure over current UHTC systems.