Functional Geopolymer Composites for Structural Ceramic Applications

The overall objective of the Phase II program is to develop a database of geopolymer-derived functional materials systems for ceramic matrix composities, including candidate materials for matrices and fiber-matrix interphase layers, which provide appropriate materials properties for performance in high temperature hydrothermal operating conditions at acceptable composite processing costs. Both the matrix and interphase design will be done using a systematic approach where desirable phases that can be derived through geopolymer processing routes are identified through study of sintered ceramics with these compositions and desirable properties of the matrix/interphase are estimated through analysis using existing micromechanical models for brittle matrix-brittle fiber systems, after which geopolymer routes for attaining these compositions and properties will be developed and optimized. Ceramic composites will be fabricated using the new compositions both by matrix infiltration routes and filament wounding routes and the mechanical properties and hydrothermal properties of these composites will be evaluated. Microstructural and compositional changes occurring during processing and hydrothermal exposure will be characterized. A detailed database of geopolymer derived composite processing-microstructure-property correlations will thus be developed.