Multilayer SiC for thermal protection system of space vehicles: Manufacturing and testing under simulated re-entry conditions

Two types of laminated multilayer silicon carbide plates were processed by tape casting, de-binding and pressureless sintering. The specimens were subject to thermal re-entry testing under conditions as derived from the HERMES study: up to 100 combined thermal and air pressure cycles were performed. After the first cycle, all samples lost about 1.5% of their initial mass. This was caused by burn-off of the carbon added as sintering aid or left after thermal decomposition of binder and plasticizer used in the tape casting process. During subsequent thermal cycles, all samples slightly gained mass due to formation of silica on the surface and partial oxidation at the core. After completing 100 cycles, microstructure and mechanical behaviour of specimens were compared to that of the as-processed material. A flexural strength higher than 100 MPa and a Young modulus of about 130 GPa were retained by all the specimens.