Experimental investigation on the indentation hardness of precursor derived Si-B-C-N ceramics

The elasto-plastic response of the precursor derived Si-B-C-N ceramics upon contact loading was determined by depth sensing nanoindentation technique. The indentation response of as-thermolyzed Si-B-C-N ceramic was compared with the heat-treated counterpart. The as-thermolyzed ceramic was X-ray amorphous and the heat-treated ceramic was phase separated and crystallized. The hardness and reduced elastic modulus values of the as-thermolyzed ceramic were similar to 16 GPa and similar to 172 GPa, respectively. The reduction in hardness to similar to 9 GPa in the heat-treated ceramic was attributed to phase separation and crystallization of SiC and Si3N4. Furthermore, high elastic recovery with a plastic work ratio of similar to 0.3 was observed and ascribed to volume controlled deformation mechanism. (C) 2013 Elsevier Ltd. All rights reserved.