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Processing of porous biomorphic TiC ceramics by chemical vapor infiltration and reaction (CVI-R) technique

Abstract:

Chemical vapor infiltration and reaction (CVI-R) is used for producing biomorphic porous TiC ceramics derived from wood and paper. The samples are first pyrolysed in inert atmosphere to yield biocarbon template structures (Cb-template). Subsequently, three routes for converting the Cb-templates into TiC ceramics are studied. The first route includes CVI-R with TiCU-Ha and the carbon biotemplate as a carbon source. The effect of methane as additional carbon source is investigated on the second route (TiCl 4-H 2-CH 4). Finally, a two step CVI process (route 3), first TiCl 4 - H 2 and subsequent TiCl 4-H 2-CH 4 is performed in order to improve the infiltration depth into the C b-template as well as to strengthen the mechanical properties of the resulting porous TiC ceramics by depositing of additional TiC. It is found, that good infiltration of wood derived Cb-templates with subsequent conversion into TiC can only be achieved with TiCl 4-H 2-CH 4 as a precursor (route 1). Paper derived TiC ceramics with good mechanical properties, however are obtained by the two step procedure (route 3).