抄録
Iron was oxidized in air at the temperature range from 873 to 1, 123K under cyclic heating and the weight increase was measured. The weight increase under cyclic heating was larger than that under continuous heating particularly at higher temperatures. The difference was larger than that obtained from the calculated value which was obtained by considering the weight increase during the heating or cooling period. Under the cyclic heating, the lowest temperature where the reaction temperature returned, and the heating rate (40K·min-1 or more) didn't affect the weight increase. However, the weight increase depended on the holding time (the time of the reaction temperature of each cycle). The larger weight increase was observed at the shorter holding time. Under the cyclic heating, the step increase of weight was observed when the reaction was proceeded to 200-250g·m-2 at 1, 073K. This might be caused by the large crack through the oxide scale which was formed during the heating or cooling process. The surface observation by SEM showed that the surface of specimen reacted under cyclic heating was covered by the oxide flakes. This flakes might be formed at each cyclic heating and also acceralated the oxidation reaction.
