Hydrophobic Surface Treatment and Hydrolysis Kinetics of Aluminium Nitride Powder

The resistance to hydrolysis of aluminium nitride (AIN) powder was improved by coating oleicacid (OA) and 8-hydroxyquinodline (HQ) on the surface of AIN particles. The treated powdersdid not react with water at 40℃ when soaked for up to 70h at a constant PH, whereas at thesame conditions the untreated AIN reacted with water after 2~10h soaking. However, with anincrease of temperature (60-80℃), the hydrolysis of the coated powder took place quickly. Thehydrolysis kinetics of AIN powder with OA and Ho films was divided into two steps, diffusioncontrol stage and chemical reaction control stage, both of which were first order reactions withactivation energies about 125kJ/mol and 114kJ/mol respectively. The observed behavior wasinterpreted by the hydrophobic films as a diffusion barned between water and AIN surface, whichwas responsible for the improvement of the hydrolysis resistance. The hydrolysis of the coatedAIN powders at high temperature was attributed to an interfacial physical bonding that was easilybroken down by errosion of water. This explanation was supported by TG-DTA, XRD and IRexamination.