C/C-SiC sandwich structures manufactured via liquid silicon infiltration

Abstract

In a new design approach, C/C-SiC sandwich structures have been realized via liquid silicon infiltration (LSI) and in situ joining method. In the first process step, carbon fibre reinforced polymer (CFRP) preforms for the planar skin plates as well as for the core structures were manufactured via warm pressing and autoclave technique, using C fibre fabrics preimpregnated with phenolic resin. Thereby two types of C/C-SiC core structures were used: foldcore and grid core. In the second process step, the sandwich components were pyrolysed separately, leading to porous C/C preforms and subsequently joined to a C/C sandwich structure, using an adhesive. In the last process step the C/C structure was infiltrated with molten Si and the SiC matrix was built up by a chemical reaction of Si and C, leading to a permanently joined C/C-SiC sandwich structure. For mechanical characterization, sandwich specimens were manufactured and tested in 4 point bending.