Manufacture and Mechanical Properties of C/C-SiC Sandwich Structures

Kurzfassung

C/C-SiC sandwich structures have been developed using liquid silicon infiltration (LSI) process and in situ joining method. They offer high specific stiffness and strength, low thermal expansion, high environmental stability and temperature resistance. Potential application areas are geometrically stable satellite structures like optical benches or high temperature structures for thermal protection systems or control surfaces in spacecraft. In this study, sandwich structures were manufactured using prepregs based on 2D carbon fibre fabrics and a phenolic resin precursor. CFRP preforms for the different types of cores and the skin panels were manufactured using warm pressing and autoclave technique. In the second step, the sandwich components were pyrolysed separately, leading to C/C preforms. For the build-up of the sandwich structure, two skin plates were joined to the core structure and subsequently, the resulting C/C sandwich structure was siliconized. Thereby, molten Si was infiltrated in the porous C/C and joining paste and the SiC matrix was built up by a chemical reaction of Si and C. The resulting C/C-SiC sandwich structures were characterized in bending, out of plane compression and shear. The effective flexural, compression and shear stiffness of the sandwich structures were determined and compared to the results obtained by analytical and Finite Element simulation.