Wet milling of Al-containing powder mixtures as precursor materials for reaction bonding of alumina (RBAO) and reaction sintering of alumina-aluminide alloys (3A)

Wet milling of powders containing metallic and ceramic particles in differe nt organic milling media has been investigated. These powders are used as p recursors for the reaction bonding of aluminum oxide (RBAO) and for the rea ction sintering of alumina-aluminide alloys (3A). An attempt is made to exp lain effects on the milling efficiency in terms of interactions between the organic medium and the particle surfaces. The effects of oxide particle an d crystal size have also been examined. The milling efficiency can be optim ized by choosing proper milling medium and a suitable particle and crystal size of the abrasive components. Highest milling efficiency was obtained wh en the powder mixture was milled in a nonpolar organic medium (cyclohexane) . The abrasion contribution of the oxide particles is more significant in s lurries of higher stability, i.e., in acetone; The area of new Al surfaces formed per milling time is discussed in terms of an in situ determination o f the water consumption, where an ethanol-water mixture was used as milling medium, and in terms of the fraction of Al oxidized per time of milling. ( C) 1999 Elsevier Science S.A. All rights reserved.