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Journal Articles

Diffusion behavior of D$$_{2}$$O in Fe$$_{3}$$O$$_{4}$$ film on Fe formed in an NaOH solution containing oxidants

Haruna, Takumi*; Miyataki, Yuki*; Hirohata, Yohei*; Shibata, Toshio*; Taniguchi, Naoki; Tachikawa, Hirokazu*

Zairyo To Kankyo, 67(9), p.375 - 380, 2018/09

This research aimed to confirm the formation of Fe$$_{3}$$O$$_{4}$$ 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$$_{2}$$O in the Fe$$_{3}$$O$$_{4}$$ film at room temperature. The results were obtained as follows. It was confirmed that Fe$$_{3}$$O$$_{4}$$ 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$$_{2}$$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$$_{2}$$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$$_{2}$$O constant. The constant amount of D$$_{2}$$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$$_{2}$$O absorbed into the film was analyzed on the basis of Fick's law for diffusion, and diffusion coefficients of D$$_{2}$$O were obtained to be 5.1$$times$$10$$^{-15}$$ cm$$^{2}$$ s$$^{-1}$$ and 9.9$$times$$10$$^{-15}$$ cm$$^{2}$$ s$$^{-1}$$ for the films formed for 1.2 and 3.6 ks, respectively. Therefore it was estimated that the diffusion coefficient of the Fe$$_{3}$$O$$_{4}$$ film was in the region from 5.1$$times$$10$$^{-15}$$ cm$$^{2}$$ s$$^{-1}$$ to 9.9$$times$$10$$^{-15}$$ cm$$^{2}$$ s$$^{-1}$$.

Journal Articles

HCM12A Cr-rich oxide layer investigation using 3D atom probe

Kikuchi, Kenji*; Okada, Noriyuki*; Kato, Mikio*; Uchida, Hiroshi*; Saito, Shigeru

Journal of Nuclear Materials, 450(1-3), p.237 - 243, 2014/07

 Times Cited Count:3 Percentile:61.51(Materials Science, Multidisciplinary)

Three-dimensional atom probe techniques were applied to the investigation on the oxide scale in 12Cr ferritic-martensitic steel, HCM12A. A duplex oxide scale was formed in lead bismuth eutectic at 450-500$$^{circ}$$C, during 5500 h. Samples were located 500-700 nm away from the boundary between magnetite and Fe-Cr spinel layers, while the total oxide layer thickness is 18 $$mu$$m. It detected super enrichment of Cr with a size of ten nm roughly, as well as depletion of Fe and enrichment of O at the same site. Surrounding the Cr super enrichment area, enrichment of Si was newly noticed due to the scanned profile of detected atom counts. It is also confirmed that Pb and Bi concentration in the observed spinel region is almost null or less than 0.01 atomic percent, which is possible detecting lowest limit.

JAEA Reports

Long-term immersion tests of engineered materials in the Tono mine; Results for metals

; ;

JNC-TN7430 2000-002, 25 Pages, 2001/01

JNC-TN7430-2000-002.pdf:3.32MB

The burial tests of mild steel and pure titanium were performed in a gallery at Tono mine to assess the corrosion resistance of these materials under goundwater environment. Specimens were placed in the container and immersed into groundwater. After the immersion period, the apperance of the surface of these specimens were observed. The corrosion product of mild steel specimen was analysed by various methods. The average corrosion rate of mild steel for 10 years was assessed by the measurement of the weight loss of carbon steel specimen. The results of the test were summerised as follows : (1)The average corrosion rate of mild steel for 10 years was assessed to be 4.36 $$times$$10$$^{-3}$$mm/y by the weight loss of the specimen. (2)The corrosion product consists of outer porous substance and inner tight corrosion product film. The former contains ferric oxide such as goethite and the latter contains ferrous oxide such as magnetite. (3)The evidence of the initiation of localised corrosion was not observed on the titanium specimens.

JAEA Reports

Effect of magnetite as a corrosion product on the corrosion of carbon steel overpack

; ; Kawasaki, Manabu*; *

JNC-TN8400 2001-001, 56 Pages, 2000/12

JNC-TN8400-2001-001.pdf:1.48MB

It is necessary to clear the effects of corrosion products on the corrosion life time of carbon steel overpack for geological isolation of high-level radioactive waste(HLW). Especially, it is important to understand the effects of magnetite because magnetite as a simulated corrosion product is reported to accelerate the corrosion rate of carbon steel. In this study, corrosion tests to reproduce the acceleration of corrosion due to magnetite was performed and the mechanism of the acceleration was investigated to evaluate the effects of magnetite as a corrosion product. Based on the results of experiments, following conclusions are obtained ; (1)Magnetite powder accelerates the corrosion rate of carbon steel. The main reaction of corrosion under the presence of magnetite is the reduction of Fe(III) in magnetite to Fe(II), but the reaction of hydrogen generation is also accelerated. The contribution of hydrogen generation reaction was estimated to be about 30% in the total corrosion reaction based on the experimental result of immersion test under the presence of magnetite. (2)Actual corrosion products containing magnetite generated by the corrosion of carbon steel protect the metal from the propagation of corrosion. The corrosion depth of carbon steel overpack due to magnetite was estimated to be about 1 mm based on the results of experiments. Even if the effect of magnetite is taken into the assessment of corrosion lifetime of overpack, total corrosion depth in 1000 years is estimated to be 33 mm, which is smaller than the corrosion allowance of 40 mm described in the second progress report on research and development for the geological disposal of HLM/ in Japan. It was concluded that the effect of magnetite on the corrosion life time of carbon steel overpack is negligible.

Journal Articles

Sorption and desorption kinetics of Np(V) on magnetite and hematite

Nakata, Kotaro*; Nagasaki, Shinya*; Tanaka, Satoru*; Sakamoto, Yoshiaki; Tanaka, Tadao; Ogawa, Hiromichi

Radiochimica Acta, 88(8), p.453 - 457, 2000/12

 Times Cited Count:13 Percentile:31.53(Chemistry, Inorganic & Nuclear)

Sorption kinetics of Np(V) on magnetite and hematite were investigated, and a sequential desorption method was applied to investigate changes in the chemical form of Np sorbed according to the amount of time they were in contact with the Np solution. It was found that the sorption process consists of fast sorption and slow sorption which reaches equilibrium in 1 h. From the results of sorption and desorption kinetics, it was concluded that the equilibrium between various chemical forms of sorbed Np was achieved in about 1 week, although the amount of sorbed Np reached an equilibrium in only 1 h.

JAEA Reports

Study on cathodic reaction control efficiency by low alloy steels

Akashi, Masatsune*; *; Asano, Hidekazu*

JNC-TJ8400 2000-014, 22 Pages, 2000/02

JNC-TJ8400-2000-014.pdf:0.75MB

Difference of hydrogen generation phenomena on the surface of the Steels were not observed between carbon steel, atmospheric corrosion resisting steel and 5%-Ni steel. Rust layer was formed on these three-type of steels by steam oxidation method. And the chemical composition of the rust for the steels were basically two(2) layers structure for the previous two steels as hematite(Fe$$_{2}$$O$$_{3}$$) based for the outer layer and magnetite(Fe$$_{3}$$O$$_{4}$$) based for the inner layer. And for the last steel, it had three(3) layer in the rust as hematite(Fe$$_{2}$$O$$_{3}$$) based for the outer layer, magnetite(Fe$$_{3}$$O$$_{4}$$) based for the intermediate layer and Ni based layer for the inner layer. These steels showed mostly same Tafel gradient in their cathodic polarization curves compare with that for no rust specimens. However, the exchange current density which reaction is assumed as a hydrogen generation reaction was largely increased. The cathodic reaction for each steels whose surface is covered by magnetite layer might be accelerated, then the corrosion rate was considered as accelerated, too.

JAEA Reports

None

Shibata, Toshio*; *; *; Tsuru, Toru*; Inoue, Hiroyuki*

JNC-TJ8400 2000-013, 38 Pages, 2000/02

JNC-TJ8400-2000-013.pdf:3.25MB

None

Journal Articles

Neutron diffuse scattering study of the high temperature phase of Fe$$_{3}$$O$$_{4}$$-I; Determination of atomic displacements at the X point in the brillouin zone

*; Ishii, Yoshinobu; Morii, Yukio; *; *; *

Journal of the Physical Society of Japan, 67(8), p.2818 - 2827, 1998/08

 Times Cited Count:22 Percentile:24.78(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Diffuse neutron scattering of the high temperature phase of Fe$$_{3}$$O$$_{4}$$

*; Ishii, Yoshinobu; Morii, Yukio; Funahashi, Satoru; *

Journal de Physique, IV, 7(1), p.585 - 586, 1997/00

no abstracts in English

Journal Articles

Chemical reactions induced by 40keV He$$^{+}$$ ions in Fe$$_{3}$$O$$_{4}$$ and $$alpha$$-Fe$$_{2}$$O$$_{3}$$

Aratono, Yasuyuki; Sagawa, Chiaki; Nakashima, Mikio; Nakada, Masami; Hojo, Kiichi; Saeki, Masakatsu

Hyperfine Interactions, 70, p.905 - 908, 1992/00

 Times Cited Count:5 Percentile:62.26(Physics, Atomic, Molecular & Chemical)

no abstracts in English

Journal Articles

Chemical effects of thermal neutron irradiation on $$alpha$$-LiFeO$$_{2}$$

Aratono, Yasuyuki; Sagawa, Chiaki; Nakashima, Mikio; Saeki, Masakatsu; *

Chemistry Letters, 1990, p.35 - 38, 1990/00

no abstracts in English

Journal Articles

Study on the reduction process of molten magnetite for ammonia synthesis catalysts by the electron microscope

Nippon Kinzoku Gakkai-Shi, 23(7), P. 426, 1959/00

no abstracts in English

Oral presentation

Diffusion behavior of heavy water in magnetite film formed on iron in basic solution

Haruna, Takumi*; Miyataki, Yuki*; Hirohata, Yohei*; Taniguchi, Naoki; Tachikawa, Hirokazu*

no journal, , 

no abstracts in English

13 (Records 1-13 displayed on this page)
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