Contact-mechanical properties at pre-creep temperatures of fine-grained graphene/SiC composites prepared in situ by spark-plasma sintering

Hertzian indentation was used to investigate for the first time the elastic–plastic behavior and contact damage evolution with temperature (in the 25–850 °C range) in air of different in situ grown graphene/SiC composites. Three SiC starting powders differing in polytypes and particle sizes were liquid-phase densified by spark-plasma sintering, thus producing ceramic composites that contain about 4 vol.% of epitaxial grown graphene flakes at the grain boundaries and have interesting differences in their microstructure. The general trend in the contact mechanical behavior is qualitatively similar among the different composites, with the elastic modulus, yield stress, and critical loads for the onset of quasi-plasticity and ring/cone cracking all decreasing with increasing temperature, with the differences at the quantitative level being explained in terms of the particular microstructure of each graphene/SiC composite.