Alumina/SiC “nanocomposites" consist of a dispersion of submicron SiC
particles in an alumina matrix. The resistance to severe wear of the
nanocomposites and the surface finish produced by a given grinding treatment
are strikingly superior to those of pure alumina with the same grain size.
We have explored the reasons for this by correlating a wide range of
variations in the basic microstructure with the wear behaviour observed,
including both the wear rate, and quantitative surface fractography of the
worn surfaces. These improved properties of the nanocomposites are shown to
be a consequence of a reduction in surface grain pullout by brittle
fracture. In “dilute” nanocomposites (<10% SiC), this is due largely to a
reduction in size of the individual pullouts. With 10% SiC nanoparticles,
however, there is also evidence that the SiC directly suppresses the
nucleation of cracking by plastic deformation of the surface. The origin of
these effects will be discussed.