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Honda, Takashi*; Yamaguchi, Shingo*
JNC TJ8400 2003-059, 55 Pages, 2004/01
JNC-TJ8400-2003-059.pdf:2.37MB
In general, it is difficult to evaluate non-destructively the corroded states of iron-based archaeological remains, as they are fully covered by thick rust formed under ground during a long period over a hundred years. The purpose of this study is to estimate the corrosion amounts of such remains with using X-ray CT and summarize the longevity of iron in soil. It has been clarified that rust and residual metallic iron can be quantitatively divided by this technique. Therefore, it is supposed that the amounts of corrosion can be figured out on the basis of thickness and density of rust. Eight remains dug out at seven relics were analyzed. The burial periods in soil were estimated to be from 1000 to 1500 years. Metallic iron remained in six remains, and the corrosion amounts were figured out to be from 0.5 to 3 mm in these periods. In addition, the soil environments of relics were analyzed, and the relation between corrosion behaviors and environmental factors was discussed. The rust was composed of outer goethite and inner magnetite layers in normally oxidizing conditions. On the other hand, a few samples were buried in slightly oxidizing environments, and these were covered by magnetite single layers. The corrosion amount of remains in such an environment was small compared to the others.
Honda, Takashi*; Yamaguchi, Shingo*
JNC TJ8400 2003-012, 89 Pages, 2003/01
JNC-TJ8400-2003-012.pdf:5.91MB
The corrosion behaviors of iron-based archaeological remains, which were dug out in six relics in Aomori-ken and Izumotalsya-keidai-iseki, were analyzed mainly with using X-ray CT. Several samples were cut and investigated on the details of metals and oxide films. The soils were also analyzed on redox-potential, resistance, chemical contents, and others. The results indicate that metal remains in 7/14 samples. The corrosion amounts of objects of Aomori-ken were estimated to be from 1 to 4mm during 400 - 1000 years. The environments were supposed to be oxidizing. On the other hands, it is supposed that two objects in Izumotaisya-keidai-iseki were in a reducing condition. The corrosion amounts were 0.5 - 2 mm. Furthermore, the corrosion behavior of the cast gas-pipe, which had been buried for about 130 years, were evaluated. By analyzing analysis data of soil, the environment is estimated to be weak oxidizing, and the maximum graphitic corrosion depth was about 7mm.
Yoshikawa, Hideki; Ueno, Kenichi; ; Honda, Takashi*; *
9th International Conference on Environmental Remediation Ra, 0 Pages, 2003/00
None
Yoshikawa, Hideki; Ueno, Kenichi; Honda, Takashi*; Yamaguchi, Shingo*; Yui, Mikazu
9th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM '03), 0 Pages, 2003/00
None
Honda, Takashi*; *
JNC TJ8400 2001-045, 102 Pages, 2002/02
JNC-TJ8400-2001-045.pdf:7.65MB
The corrosion of iron-base archaeological artifacts, which were dug out in Iyomai-7 (Chitose-shi, Hokkaido) and Izumo-Ooyashiro-Keidai (Taisha-machi, Shimane-ken) sites, was investigated by using X-ray CT, XRD, atomic absorption spectroscopy and EDX techniques. While the artifacts such as swords in Iyomai-7 site had been buried in the ground for 400-500 years, metallic iron remained in the swords and the corrosion amounts were estimated to be 2-5mm. Several artifacts were investigated among a lot of iron rings and nails buried beside huge pillars of the ancient shrine. Those artifacts had been in ground for 730-750 years. The corrosion amounts were estimated to be 3-5mm. As the both soil environments are supposed to be oxidizing, the outer oxide layers of all speicies are composed of goethite and soil. Further, it was clarified that perfectly corroded ones had hollow structures. In this study, the sampling method of species, the corrosion environmental factors, and the corrosion kinetic models were also evaluated.
Honda, Takashi*; *
JNC TJ8400 2000-007, 200 Pages, 2000/02
JNC-TJ8400-2000-007.pdf:14.84MB
In general, it is very difficult to evaluate the residual state of metallic iron and the original shape of iron-base archaeological artifacts, as these are covered by thick oxide films formed in the ground during over several hundred years. The purpose of this research is to quantify the corrosion of an artifact such as base, knife, and nail, which was digged out of the relics about 500-1,000 years old. (1)The outer oxide film layer and the inner metallic iron can be quantitatively divided by using X-ray CT method. Furthermore, the original surfaces of artifacts can be estimated from the obtained images, even if the metallic iron has corroded completely. The X-ray CT images were also compared with those obtained by X-ray transmission inspection. (2)The corrosion amounts and rates were evaluated on the basis of thicknesses, densities, and iron concentrations of oxide films. (3)The characteristic differences between ancient iron and modern carbon steel were evaluated by analyzing the ancient iron slag.