抄録
Titanium plates covered with anodic oxide films with thicknesses of approximately 10 µm were embedded in a mixture of iron, graphite, and alumina powders, and then heated in the temperature range of 1073–1373 K for 3.6 ks in a nitrogen flow. We refer to this heat treatment method as “iron-powder pack (IPP) treatment”, and its ability to reduce the anodic oxide film was examined inclusive of a diffusion phenomenon of carbon and nitrogen into the film. From X-ray diffraction results, the film consisting of rutile and anosovite was gradually converted to titanium nitride with increasing heating temperature. The diffusion of carbon was also confirmed in the film after the IPP treatment. However, such a remarkable change was not achieved by heating without the powder mixture. This indicates that the powder mixture has an important role in reducing and carbonitriding the anodic oxide film. A porous structure in the film formed by anodic oxidation was retained regardless of the heating temperature in the IPP treatment. On the other hand, the peeling of the film from the titanium plate occurred through the IPP treatment at 1373 K. This would be caused by the accumulation of carbon monoxide gas, which was generated by the reduction of the oxide film.
