Improved hardness and hierarchic influences on wear in submicron sintered alumina

Pressureless sintering is used to produce submicron alumina bodies with a hardness that equals the level of advanced hot-isostatically pressed Al2O3/TiC composites with 35 vol.% carbide. Wear can be reduced by almost one order of magnitude by reducing the grain size from 4 to 0.4 μm, but the grain size effect on wear strongly depends on the environment. Wear is governed by the pull-out behaviour of grains with a secondary influence of the hardness. Therefore, the hierarchic order of the parameters which affect wear is dominated by the micromechanical stability of the grain boundaries.