Reformation of fine powdery materials through mechanochmiecal effects

II. Change in the sintering behavior due to mechanical activation

Abstract

Fine grained, well-dispersed pure α-Al₂O₃ was ground in a centrifugal ballmill, compressed under 18 and 100MPa, and fired in air at 1050-1550°C. For dense compacts, the sinterability of the activated material was higher up to the relative density, ρF, 85%. However, ρF was much lower for the ground material, when the compact was made at a lower pressure, presumably because of the inhomogeneity of the compact including hard aggregates. SEM observation revealed that the appreciable neck-and grain growth took place at temperatures as low as 1100°C for the activated material due to the enhanced surface diffusion.