Effects of Manufacturing Processes on Hydration Ability of High Purity .ALPHA.-Al2O3 Powders

Commercial sub-micron high purity alpha-Al2O3 powders ground and not ground in the manufacturing process, produced by three different processes (in-situ CVD, hydrolysis of aluminium alkoxide and thermal decomposition of ammonium alum methods), were thermally hydrated and the effects evaluated by DRIFT spectroscopy in dry air atmosphere. The hydration process was conducted by placing all powders, without contact with water, in a modified pressure cooker heated inside an oven at 100 C under water saturated pressure. The surface of powders ground in the manufacturing process was easily hydrated by the hydrothermal treatment and aluminium trihydroxide peaks were seen on the DRIFT spectra. The results demonstrate that grinding in the manufacturing process affects the hydration ability of high purity alpha-Al2O3 powder surfaces. 20 refs.