Diffusion behavior of D
O in Fe
O
film on Fe formed in an NaOH solution containing oxidants
Haruna, Takumi*; Miyataki, Yuki*; Hirohata, Yohei*; Shibata, Toshio*; Taniguchi, Naoki
; Tachikawa, Hirokazu*
This research aimed to confirm the formation of Fe
O
film on Fe immersed in aqueous 45 mass% NaOH solution containing some oxidants at the boiling temperature, to recognize the optimum immersion time for the formation of thick and protective film, and to reveal the absorption behavior of D
O in the Fe
O
film at room temperature. The results were obtained as follows. It was confirmed that Fe
O
film was formed on Fe immersed in the NaOH solution for a time more than 0.6 ks, and the film thickness increased parabolically with an increase in the immersion time. D
O absorption test was carried out to the films formed in the NaOH solution for immersion times of 1.2 and 3.6 ks. An amount of D
O absorbed into the film increased with an increase in an absorption time up to 1000 ks, and an absorption time more than 1000 ks made an amount of D
O constant. The constant amount of D
O was larger for the film formed on Fe immersed in the NaOH solution for 3.6 ks than that for 1.2 ks. The transient of the amount of D
O absorbed into the film was analyzed on the basis of Fick's law for diffusion, and diffusion coefficients of D
O were obtained to be 5.1
10
cm
s
and 9.9
10
cm
s
for the films formed for 1.2 and 3.6 ks, respectively. Therefore it was estimated that the diffusion coefficient of the Fe
O
film was in the region from 5.1
10
cm
s
to 9.9
10
cm
s
.