Fugitive Interfacial Carbon Coatings for Oxide/Oxide Composites

Abstract

The effectiveness of fugitive interfacial carbon coatings in Nextel™ 720‐based composites was investigated. Dense (>90%) matrix (calcium aluminosilicate, 0° and ±45°) composites and porous matrix (mullite/alumina, eight‐harness satin fabric) composites were fabricated and tensile tested in two control conditions (uncoated or carbon‐coated) and with the carbon removed (fugitive interface). Results indicated that carbon removal in dense matrix composites did not significantly change unidirectional composite strength, even after long‐term exposure at 1000°C. For porous matrix composites, composite strength was independent of the fiber/matrix interface, even after exposure at 1150°C for 500 h in air.