A ceramic nanocomposite with enhanced hardness based on corundum modified with carbon

Results of examination of the effect of modifying the grain boundaries of nanostructured corundum with carbon nanoclusters on the nanocomposite hardness are reported. The nanocomposite hardness was found to be increased to 28 GPa. This value is substantially higher than the hardness of single-crystal corundum at any crystallographic plane (23 GPa). Carbon was present at grain boundaries in the obtained nanocomposite owing to the fact that this nanocomposite was sintered from clusters containing corundum nanograins coated with several C$_{60}$ layers. The structure of samples was investigated by transmission electron microscopy and Raman spectroscopy, and their hardness was measured by indenting and scratch testing.