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Ueno, Fumiyoshi; Komatsu, Atsushi; Igarashi, Takahiro; Yamamoto, Masahiro
Proceedings of European Corrosion Congress 2014 (EUROCORR 2014) (USB Flash Drive), 10 Pages, 2014/09
In this paper, the effect of phosphorous concentration in grain boundary (GB) on intergranular corrosion (IC) progress was studied to understand GB corrosion behavior of stainless steels in boiling nitric acid solution. Phosphorus (P) added extra high purity type 310 stainless alloy was corroded in boiling nitric acid solution, and P in GB was detected by three-dimensional atom probe. IC progress considering with P profile in GB was studied by numerical simulation using cellular automaton method. As the results, we concluded that P concentration change around 1.4at% in GB of the alloy caused IC rate change in boiling nitric acid solution. The developed numerical method could simulate GB corrosion change with P distribution in GB.
Nemoto, Yoshiyuki; Miwa, Yukio; Tsuji, Hirokazu; Tsukada, Takashi
Nihon AEM Gakkai-Shi, 11(4), p.242 - 248, 2003/12
no abstracts in English
; Fujisaku, Kazuhiko*; *; ; Koyama, Tomozo
JNC TN8410 2001-013, 255 Pages, 2001/05
JNC-TN8410-2001-013.pdf:24.24MB
Mock-ups of acid recovery evaporators which are made of Ti-5% Ta alloy and Zr were tested under inactive condition for forty thousands hours to improve a corrosion resistance of acid recovery evaporator in Tokai reprocessing plant (TRP). The mock-up unit was designed and produced referring to the specification of acid recovery evaporator in TRP and the evaporation performance of the mock-up was 1/27 of TRP. A long-term durability of both evaporators was demonstrated by results of operation data, evaporation performance and corrosion resistance. The mock-up unit did not suffer from any trouble during the running test and the operation data such as temperature, flow, concentrations of nitric acid and metal ions were fairly stable within standard condition. As for the corrosion resistance, cracks and local corrosion such as intergranular attack were not observed on both evaporators after the running test, and a corrosion of weld was not selective. The average corrosion rates at measuring points were less than 0.1mm/yr, respectively, however, thickness of the Ti-5% Ta alloy evaporator was slightly reduced at all points of vapor phase region. In addition, from the result by test coupon, it is found that both materials have low susceptibility to stress corrosion cracking in this environment. The destructive inspection showed that the mechanical properties of both materials were not degraded during the running test. Finally, the total running time of the mock-up unit is much more than a maximum running time of acid recovery evaporator made of stainless steel in TRP (nearly 15,000 hours). On the basis of the test results, an excellent durability of Ti-5% Ta alloy and Zr evaporators under was successfully demonstrated throughout the mock-up test from an engineering perspective.
Doi, Masamitsu; Kiuchi, Kiyoshi; Yano, Masaya*; Sekiyama, Yoshio*
JAERI-Research 2001-020, 17 Pages, 2001/03
JAERI-Research-2001-020.pdf:0.7MB
no abstracts in English
Saito, Junichi; Morinaga, Masahiko*; Kano, Shigeki
PNC TN9410 98-072, 97 Pages, 1998/07
Research on structural materials which will be utilized even in the severe environment of high-temperature liquid alkali metals has been promoted in order to develop the frontiers of materials techniques. The super-heat resisting alloys which are based on refractory metals, Nb and Mo, are aimed as promising materials used in such an environment. The corrosion resistance in liquid Li and the mechanical properties such as creep and tensile strengths at high temperatures are important for these structural materials. On the basis of many expeliments and analyses of these properties at 1473K, the material design of Nb-based and Mo-based alloys has-been carried out successfully. In this report, all the previous experimental results of corrosion tests in liquid Li were summarized systematically for Nb-based and Mo-based alloys. The corrosion mechanism was proposed on the basis of a series of analyses, in particular, focussing on the deposition mechanism of corrosion products on the surface and also on the initiation and growth mechanism of cracks on the corroded surface of Nb-based alloys. The principal results are as follows. (1)For the deposition mechanism, a reaction took place first between dissolved metallic elements and nitrogen which existed as an impurity in liquid Li and then corrosion products (nitrides) precipitated on the metal surface. Subsequently, another reaction took place between dissolved metalic elements in liquid Li, and corrosion products (intermetallic compounds) precipitated on the metal surface. The composition of deposited corrosion products could be predicted on the basis of the deposition mechanism. (2)For the crack initiation mechanism, the chemical potential diagrams were utilized in order to understand the formation of Li-M-O ternary oxides which caused cracks to be formed on the corroded surface. Consequently, it was evident that not only the concentration of the dissolved oxygen in the alloy but also the concentration of Li which ...
Tachi, Yoshiaki; Hirakawa, Yasushi; Kano, Shigeki; Yoshida, Eiichi
PNC TN9410 98-054, 57 Pages, 1998/01
It has been progressed as the Frontier Materials Research to research and develop ceramics to apply for several components of fast breeder reactor using liquid sodium as coolant instead of metallic materials. Grain boundary of ceramics has peculiar properties compared with matrix because most of ceramics are produced by hardening and firing their raw powders. Some previous researchers indicated that ceramics were mainly corroded at grain boundaries by liquid sodium, and ceramics could not be used under corrosive environment. Thus, it is the most important for the usage of ceramics in liquid sodium to improve corrosion resistance of grain boundaries. In order to develop the advanced ceramics having good sodium corrosion resistance among fine ceramics, which have recently been progressed in quality and characteristics remarkably, sodium corrosion behaviors of typical sintering additives such as MgO, Y
O
and AIN etc. have been examined and evaluated. As a result, the followings have been clarified and some useful knowledge about developing advanced ceramics having good corrosion resistance against liquid sodium has been obtained. (1)Sodium corrosion behavior of MgO depended on Si content. Samples containing large amount of Si were corroded severely by liquid sodium, whereas others with low Si contents showed good corrosion resistance. (2)Both YO and AIN, which contained little Si, showed good sodium corrosion resistance. (3)MgO, YO and AIN ale thought to be corroded by liquid sodium, if they contain some SiO. Therefore, in order to improve sodium corrosion resistance, it is very important for these ceramics to prevent the contamination of matrix with SiO through purity contlol of their raw powders.
Morinaga, Masahiko*; Kano, Shigeki; Inoue, Satoshi*; *; Tachi, Yoshiaki; *; *
PNC TY9623 94-004, 87 Pages, 1994/03
None
Tsukada, Takashi; Shiba, Kiyoyuki; Nakajima, Hajime; ; Kitagawa, Isamu; ; Sekino, Hajime; ; Itonaga, Fumio; Ishikawa, Akiyoshi
JAERI-M 92-169, 26 Pages, 1992/11
no abstracts in English
*
PNC TJ9605 91-001, 28 Pages, 1990/10
The present report describes the results of studies performed sa a part of the results of "CORROSION TESTS OF CLADDING INNER SURFACE COATING" during a period of Feb. 20 - Mar.30, 1990. In the present study, corrosion tests have been carried out with CsOH to evaluate corrosion resistance of ferritic stainless steel and coated stainless steel. The following results were drawn from the present study (1)Corrosion tests of austenitic and ferritic stainless steel with ScOH were made at temperatures of 500-700
C. After corrosin tests, intergranular attack was found to occur in the austenitic steel, however, there was no intergranular attack in the ferritic steel. Ferritic steel appears to have corrosion resistance to liquid CsOH superior to austenitic steel. (2)Corrosion tests between Ni-Ti, Ti, Al coatings on stainless steel and CsOH were made at temperature of 500-700C. Ni-Ti and Al coated stainless steel showed no intergranular attack, though the coatings were locally detached from the stainless stell substrates. Intergranular attack was observed in the Ti coated stainless steel. Ni-Ti and Al coating seem to be useful for reduction of intergranular attack of stainless steel cladding.
; Kondo, Tatsuo
Tetsu To Hagane, 70(1), p.112 - 119, 1984/00
no abstracts in English
JAERI-M 8688, 44 Pages, 1980/02
no abstracts in English
Kawasaki, Masayuki; ; Kondo, Tatsuo
Nihon Kinzoku Gakkai-Shi, 25(1), p.76 - 79, 1961/00
no abstracts in English
Kato, Chiaki; Soma, Yasutaka; Ueno, Fumiyoshi; Okada, Kiyotaka*; Ebina, Tetsunari*; Kano, Yoichi*; Nakayama, Jumpei
no journal, ,
no abstracts in English
Igarashi, Takahiro; Komatsu, Atsushi; Irisawa, Eriko; Kato, Chiaki
no journal, ,
Since high-concentration boiling nitric acid with oxidizing metal ions is used in reprocessing process of spent nuclear fuel, it is quite severe corrosive environment for stainless steel, and cause intergranular corrosion. For long-term stable and safety operation of reprocessing and prediction of life of structure, it is necessary to predict the amount of corrosion due to intergranular corrosion over several decades. However, since the error in the estimation by the amount of long-term corrosion from the results of conventional corrosion tests of several days is large, improvement of accuracy has been one of the problems. In this study, intergranular corrosion behavior was predicted using the cellular automatic intergranular corrosion model with the parameters from measured data of short-time corrosion test, and the prediction of long-term corrosion behavior was evaluated by comparing with the results of long-term mockup corrosion test. These results showed that the amount of corrosion could be predicted more accurately from a short-term corrosion test.
