Strong pinning effect of alumina/nanodiamond composites obtained by pulsed electric current sintering

A small fraction (5 vol.%) of detonation nanodiamonds, or DND, acts as a remarkably effective boundary pinning agent in alumina throughout a wide sintering temperature range (from 1200 up to 1700 °C). This is the first time that such a strong grain growth inhibitory effect is observed for any of the alumina based composites of similar characteristics reported in the literature. These nanocomposites were consolidated by pulsed electric current sintering (PECS) and present bending strength (550 MPa) and toughness (5.2 MPa m1/2) values significantly higher than the ones corresponding to alumina compacts obtained under the same sintering conditions.