抄録
Thermal oxidation of TiN, CrN and TiAIN films were studied in air at temperatures from 923K to 1, 173K. These nitride films were deposited onto stainless steel substrates using an arc ion-plating appratus. Oxidation rates were calculated by the weight changes with time. Formed oxide layers were analyzed by XRD, SEM, and SAM. The oxidation rates were proportional to square-root of reaction time. This means the oxidation are controlled by diffusion. The difference of oxidation rates among films materials were compared from the Arrhenius plots of the rate constant. The calculated activation energy of 136 kJ/mol for oxidation of TiN was less than that of 180 kJ/mol for oxygen diffusion in TiO2. This difference suggests that the oxidation of TiN is enhanced by grain boundary diffusion of oxygen in formed oxide film. The activation energy for CrN was 251 kJ/mol, which was almost the same value as that of diffusion of Cr ion in Cr2O3. The oxidation reaction of Ti0 9Al0.1N is much faster than that of Ti0.6A10.4N. The activation energies were 215 kJ/mol for Ti0.9Al0 1N and 471 kJ/mol for Ti0.6Al0 4N, respectively. The activation energy for Ti0 6A10 4N was almost the same as that of diffusion of Alion in Al203.
