Ar-O2-SO2雰囲気中におけるコバルトの腐食
1986 年 50 巻 4 号 p. 403-409
詳細
1986 年 50 巻 4 号 p. 403-409
Corrosion experiments of cobalt were carried out at 873∼1173 K in various Ar-O2-SO2 atmospheres. The change in the corrosion amounts was automatically recorded by massgravimetry. Scale structures were examined by X-ray diffractometry, optical microscopy and EPMA.
The corrosion kinetics followed the parabolic rate law. The rate-controlling process of the reaction was considered to be mainly the outward diffusion of Co ion. The corrosion products consisted of CoO, Co3O4, CoS1.035, Co9S8 and α-CoSO4. The corrosion amounts reached a maximum at about 948 K in almost all atmospheres.
Duplex scale structures consisting of oxides and sulfides were formed at lower temperatures, and a single oxide layer was formed at elevated temperatures. The activation energy was found to be about 140 kJ/mol at temperatures above 1000 K.
