Nanoindentation characterization of submicro- and nano-sized liquid-phase-sintered SiC ceramics

Submicro- and nano-sized liquid-phase-sintered SiC ceramics were mechanically tested by nanoindentation in the peak load range 5-400 mN. The submicro-sized sample showed a marked indentation size effect which the nano-sized samples did not exhibit. The relevance of indentation depth with respect to the microstructural scale has been outlined. In the investigated grain-size range, the hardness dependence on the grain size could be described by a load-dependent inverse Hall-Petch relation. Young's modulus was less microstructure- and load-dependent. Because of the very fine microstructure, the nano-sized SiC materials gave lower elastic values than the submicro-sized SiC ceramic.