Process Optimization of Ceramic Matrix Composites for Ultrasonically Absorptive TPS Material

摘要

Boundary layer transition control by ultrasonically absorptive TPS material offers the possibility to reduce heat fluxes during hypersonic flight. The potential of ultrasonically absorptive carbon fiber reinforced carbon (C/C) based materials for passive boundary layer transition control was already proven in experiments. However, C/C exhibits some disadvantages especially the limited oxidation resistance and its low mechanical strength is considered critical during hypersonic flight. Thus, this paper is addressed to the development of a porous and ultrasonically absorptive fiber reinforced ceramic material based on a silicon carbide (SiC) matrix. The presented material development is of fundamental importance for the realization of a hypersonic vehicle, since the requirements for this application is, among others, high temperature and thermal shock resistance, low thermal expansion and oxidation resistance. This paper describes the fabrication process of a carbon fiber reinforced silicon carbide (C/C-SiC) ceramic manufactured by Liquid Silicon Infiltration (LSI) with a defined channel structure in order to achieve ultrasonically absorptive properties. In particular, the influence of the green body fabrication on the final material property is investigated. Therefore, different carbon fiber reinforced plastic (CFRP) are formed via autoclave, resin transfer moulding (RTM) and hot pressing techniques using commercially available 0°/90° hybrid fabrics impregnated with a phenolic resin. The manufactured C/C-SiC materials will be assessed on their important acoustic properties like porosity, pore size distribution and length specific flow resistance. Finally, the data will be discussed and compared to experiments conducted with the already characterized C/C material.