2006 Volume 47 Issue 8 Pages 1902-1905
Vacuum degassing is essential in the preparation of RS P/M aluminum alloys to remove adsorbates and for the decomposition of hydrated-Al2O3 on the powder surface. Changes in the surface characteristics during vacuum degassing were investigated by X-ray photoelectron spectroscopy and temperature-programmed desorption measurement. Hydrated-Al2O3 decomposition to crystalline-Al2O3 and hydrogen desorption on the surface of argon gas-atomized aluminum powder occurred at 623 K and 725 K, respectively. This temperature difference suggests that the reaction converting hydrated-Al2O3 to crystalline-Al2O3 during vacuum degassing should be divided into the two reactions “2Al+Al2O3·3H2O→2Al2O3+6Hsurf” and “6Hsurf→3H2”.