Mechanism of the Wettability of Alumina by Polyphosphate Glasses

Abstract

Polyphosphates glasses may be used as a sintering aid for alumina based ceramics composites. The knowledge of the mechanism of the wettability of alumina by melted polyphosphate glasses is an fundamental point for the sinterring control. We show that the wettability on inactive alumina is obtained in two stages . The first stage consists in a reaction between alumina and phosphorus pentoxyde exhaust from the melted glass bulk.The formation of a thin layer of aluminium phosphate permits, in a second stage, the wettability of the alumina. So the control of wettability needs to adapt the glasses formula to the phosphorus pentoxyde exhaust power in melted phase.