Innovative Processing of Ceramic Core/Composite Skin Structures

The objective of this proposal is to demonstrate the fabrication of ceramic core/composite skin structures using liquid infiltration techniques. The core will be porous alumina rods or tubes and the composite skin will be fabricated via infiltration with alumina sol of an aluminosilicate fabric wrapped around the core. Heating for drying and sintering will be accomplished using both conventional furnace and microwave energy. The properties and performance of the resulting composites will be compared through microstructural and mechanical evaluations. Mechanical strength of the flexural test specimens sectioned from core/skin composites will be measured before and after isothermal exposure and theraml shock measurements will also be made. A continuous microwave processing system for use in Phase II will be designed during this project. Anticipated Benefits: These core/skin structures have the potential to provide the fracture toughness and flaw tolerance of ceramic matrix composites at a fraction of the processing cost. Applications include nozzle flaps, combustor liners, vanes, seals, ducting and blades for aerospace turbines, as well as components for industrial turbines, especially low NOx combustors