Abstract: The resistance to hydrolysis of aluminium nitride (AlN) powder was improved by coating oleic acid (OA) and 8-hydroxyquinodline (HQ) on the surface of AlN particles.
The treated powders did not react with water at 40℃ when soaked for up to 70h at a constant pH, whereas at the same conditions the untreated AlN reacted with water
after 2～10h soaking. However, with an increase of temperature (60～80℃),the hydrolysis of the coated powder took place quickly. The hydrolysis kinetics of AlN
powder with OA and HQ films was divided into two steps, diffusion control stage and chemical reaction control stage, both of which were first order reactions with activation
energies about 125kJ/mol and 114kJ/mol respectively. The observed behavior was interpreted by the hydrophobic films as a diffusion barried between water and AlN surface, which
was responsible for the improvement of the hydrolysis resistance. The hydrolysis of the coated AlN powders at high temperature was attributed to an interfacial physical
bonding that was easily broken down by errosion of water. This explanation was supported by TG--DTA, XRD and IR examination.

Key words: aluminium nitride powder, hydrolysis, kinetics, hydrophobic films, surface treatment