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Volume 65 (2011)
- Issue 6 Pages 315-
- Issue 5 Pages 263-
- Issue 4 Pages 185-
- Issue 3 Pages 127-
- Issue 2 Pages 63-
- Issue 1 Pages 1-
Volume 65, Issue 2
Displaying 1-9 of 9 articles from this issue
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Greeing
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Hiroyuki Inoue2011 Volume 65 Issue 2 Pages 63-
Published: 2011
Released on J-STAGE: September 27, 2012
JOURNAL FREE ACCESSDownload PDF (679K)
Special Issue : “Analytical Study on the Mechanism of Corrosion, and the Development of the Techniques
for Evaluating the Severity of Corrosion in Salt-Manufacturing Environment”
Commentary
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Hiroyuki Inoue, Akio Nakamura2011 Volume 65 Issue 2 Pages 64-69
Published: 2011
Released on J-STAGE: September 27, 2012
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Atsushi Naganuma, Kazuhisa Azumi2011 Volume 65 Issue 2 Pages 70-75
Published: 2011
Released on J-STAGE: September 27, 2012
JOURNAL FREE ACCESSDownload PDF (1974K)
Original Paper
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Hiroyuki Inoue, Akio Nakamura2011 Volume 65 Issue 2 Pages 76-80
Published: 2011
Released on J-STAGE: September 27, 2012
JOURNAL FREE ACCESSAn index of the susceptibility to stress corrosion cracking (SCC), ISCC of solution-annealed type-304 stainless steel (SS) was measured in a simulated concentrated brine in which the 10 mg/L of cupric, cuprous, nickel and zinc ion (Cu2+, Cu+, Ni2+, Zn2+) were dissolved, in order to evaluate the effect of a minute quantity of metal ions in concentrated chloride solutions on the SCC of SS. The index for the simulated concentrated brine to which the 10％ O2-Ar and the pure-O2 were exposed was also measured. ISCC was inversely proportional to the molality in the electrochemical equivalent of the copper ions, as well as the dissolved oxygen in the test solution, regardless of the kinds of these chemical species; ISCC decreased with on increase in SCC susceptibility. ISCC decreased with the addition of minute quantities of Ni2+ and Zn2+ when they were done singly. However, in the case where Ni2+ or Zn2+ was simultaneously added with Cu2+, ISCC was lower than that for the solution to which the same concentration of Cu2+ was solely added.View full abstractDownload PDF (965K) -
Akihiro Yabuki, Akihiro Kawashima2011 Volume 65 Issue 2 Pages 81-87
Published: 2011
Released on J-STAGE: September 27, 2012
JOURNAL FREE ACCESSDamage to copper alloys from the impact of sodium chloride particles in a slurry solution was investigated using a rotating cylinder electrode testing apparatus. A test for two types of copper alloys, 10Ni-Cu (C7060) and 30Ni-Cu (C7150), was carried out under a flowing slurry solution of 20 wt% at temperatures ranging from 20 to 80 °C. The impact condition of the particles was elucidated by means of measuring the shape and area of the impact scar generated by the impact of a solid particle in the apparatus, resulting in a velocity of 1.5 m/s and a narrow angle of 6°. Judging by the loss of mass for the specimen, the polarization resistance measured by electrochemical methods, and the surface appearance after the test, erosion was not caused by the impact of the sodium chloride. However, particle impact did accelerate corrosion. The damage to copper alloys from the impact of sodium chloride particles increased as the temperature of the solution increased. Corrosion damage for both copper alloys 30Ni-Cu and 10Ni-Cu were almost identical, although the content of the nickel differed. The properties of the corrosion product film that formed on the surface of the alloys were considered as part of the corrosion damage.View full abstractDownload PDF (2088K) -
Takaomi Tsugawa, Yutaka Watanabe, Hiroshi Abe2011 Volume 65 Issue 2 Pages 88-96
Published: 2011
Released on J-STAGE: September 27, 2012
JOURNAL FREE ACCESSConstant strain SCC tests have been performed on five kinds of austenitic alloys, SUS316L, YUS270, NAS254N, NAS354N, and C-22, in simulated salt production environments. From the results of the SCC tests, susceptible conditions to SCC for each alloy. were clarified SUS316L and YUS270 were susceptible to SCC, but NAS254N, NAS354N, and C-22 were not susceptible in the salt production environments. Cold rolling increased SCC susceptibility for SUS316L and YUS270. And there was no potent influence on SCC resistance by a change in atmosphere, judging from the SCC test results under conditions of bubbling O2 and N2 gas only in bittern.
The material selection guideline for salt production plants has been determined based on both the test results and reported SCC experiences in actual plants. The material selection guideline for the salt production environmentsis as follows;
· It is possible to apply SUS316L to the condensation process.
· It is reasonable to apply super stainless steel of over 40 in PRE to low density crystallization process.
· If it is necessary to avoid all local corrosion in high density crystallization processes and later, super stainless steel of over 50 in PRE or Ni-base alloys should be applied.
(Pitting Resistance Equivalent: PRE = Cr + 3.3Mo + 20N)View full abstractDownload PDF (1486K) -
Hitoshi Yashiro, Kei Araki, Seung-Taek Myung, Eiich Suzuki2011 Volume 65 Issue 2 Pages 97-104
Published: 2011
Released on J-STAGE: September 27, 2012
JOURNAL FREE ACCESSA dissolved oxygen monitoring system has been developed for better control of corrosion problems in salt producing plants. The limiting current density for the reduction of oxygen on a rotating Pt electrode is determined for flowing solutions sampled out from plant lines. The current density is then converted into relative oxygen concentration referring to the current densities for both deoxygenated and fully erated sample solutions. The oxygen concentration in the fully aerated sample solution can be estimated satisfactorily using alting-out parameters, which allows convenient determination of absolute concentration of dissolved oxygen in the sample. The activity of Pt electrodes can be maintained in an enhanced condition by the cyclic polarization anodically to 0.7 V (Ag/AgCl). The existence of Cu2+ in the synthetic brine above 1 ppm interferes with the oxygen analysis, electrodepositing on Pt during the cathodic polarization. Meanwhile, the anodic current peak for the stripping of the deposited Cu can be used for determination of Cu2+ in the solution. During the cathodic reduction of oxygen dissolved in the brine containing Fe2+ above 1 ppm, Fe(OH)2 deposited on the Pt electrode due to the surface alkalization. It causes a serious interference with the oxygen reduction reaction. Ni2+ ion up to 5 ppm showed a scare effect on the electroreduction of oxygen on the rotating Pt electrode. These detrimental effects could be eliminated using a cation exchange method.View full abstractDownload PDF (1159K) -
Hideo Cho, Ken Yasui, Tomohiko Yoshihara, Takuma Matsuo2011 Volume 65 Issue 2 Pages 105-113
Published: 2011
Released on J-STAGE: September 27, 2012
JOURNAL FREE ACCESSThis study aims to detect and monitor the initiation and progression of corrosion that occurs at a flange connection using an acoustic emission technique, and to investigate the correlation between acoustic emission parameters such as hit rate and frequency component of AE and the corrosion progression. We first monitor AE from the corrosion in a crevice of an assembled flange under corrosion potential control in order to investigate the feasibility of AE monitoring for corrosion detection. Many burst type AE waves were detected during testing and most of the AE source locations agreed fairly with the corrosion area. Next, AE monitoring for corrosion at a flange connection under a continuous flow of artificial concentrated sea water was performed with four PZT-type AE sensors. The AE generation rate during testing equaled 10 to 30 events / hour. Peak frequency of detected AE shifted higher to 300 kHz with the progression of corrosion. Using an optical fiber AE monitoring system developed in-house, the AE from corrosion in a crevice was also monitored. This system can monitor AE for three flanges with one optical fiber. These sensors detected AE from corrosion at an individual flange under continuous flow test. As a result, it was found that the AE method is a potential tool for monitoring corrosion at a flange connection in salt product plants.View full abstractDownload PDF (4030K)
Review
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Akihiro Yabuki2011 Volume 65 Issue 2 Pages 114-120
Published: 2011
Released on J-STAGE: September 27, 2012
JOURNAL FREE ACCESSThis review summarizes research on the near-wall hydrodynamic conditions in a jet-in-slit corrosion testing apparatus for flow-induced corrosion testing, and includes a review of the performance of the apparatus in the flow-induced corrosion testing of copper alloys in a high-salt-concentration environment. The near-wall hydrodynamic conditions on the specimen surface in the apparatus were measured with pressure gauges. The distribution of near-wall velocities and velocity fluctuations in vertical and horizontal directions to the specimen surface were determined. As a result, the hydrodynamic parameters exhibited differing distributions, and the apparatus was useful in investigating the relationship between hydrodynamic conditions and material damage. Flow-induced corrosion tests for copper alloys were carried out in a high-salt-concentration environment using the jet-in-slit corrosion testing apparatus. As the salt concentration increased, the corrosion damage increased during intense flow. During static flow, however, corrosion was not affected by the salt concentration of the solution. A spongy film was confirmed on the surface during static flow, but no film was observed on the surface during intense flow. When the temperature of the solution increased, corrosion damage also increased regardless of flow conditions. As dissolved oxygen increased, corrosion damage also increased.View full abstractDownload PDF (2116K)
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