MECHANICAL PROPERTIES OF POROUS BIOMORPHIC SiC

Biomorphic SiC (bioSiC) materials fabricated by silicon infiltration of charcoal preforms were studied. As a result of this process, a porous SiC ceramic with remanent silicon partially filling the pores was obtained. This remanent silicon can considerably alter the mechanical properties of the bioSiC but it can be effectively removed by reaction with a mixture of HF and HNO3 producing a clean porous bioSiC. A comparison was made of the mechanical properties of bioSiC from preforms of beech, eucalyptus and pine, with and without remanent silicon. High-temperature mechanical properties were studied from deformation tests in compression at constant strain rate. Microstructural characterisation of the samples, before and after the mechanical tests, was performed by SEM. 13 refs.