Characterisation of a surface treated AlN powder in aqueous media

The role of an anionic surfactant, which can act as both a deflocculant and a hydrolysis depressor, has been examined on the hydrolysis of a surface treated aluminium nitride, AlN, powder using a range of characterisation techniques. It has been determined that the initial hydrophobic surface treatment serves only to minimise the contact between water molecules and the particles and to enable the adsorption of the surfactant. The latter is the main factor preventing the hydrolysis of the powders during slip preparation. The amount of surfactant needed to achieve complete coverage of the AIN powder has been determined and found to be at a level of 1 wt% addition. At this level, the surfactant is capable of largely suppressing hydrolysis for periods of up to 60 days at room temperature. Without the surfactant, a substantial degree of hydrolysis occurs in under 50 h. The mechanism by which the surfactant depresses hydrolysis has also been defined and is explained in terms of a protecting shell which is formed as a result of adsorption of surfactant. (C) 1999 Elsevier Science Ltd. All rights reserved.