CORROSION ENGINEERING
Online ISSN : 1884-1155
Print ISSN : 0010-9355
Volume 39, Issue 9
Displaying 1-6 of 6 articles from this issue
  • Masayoshi Kato, Nozomu Fukumoto, Yuzhen Lin
    1990 Volume 39 Issue 9 Pages 461-466
    Published: September 15, 1990
    Released on J-STAGE: October 30, 2009
    JOURNAL FREE ACCESS
    In our previous works, aluminium ion was found to serve as effective inhibitor for iron corrosion in water. However, the ion is partly hydrolyzed to form AlOH2+ ion, which cause the solution slightly acidic (pH=4.3). It follows that neutralization is inevitable for discharge. In order to overcome this defect, aluminium-ligand system was examined. Among many ligands investigated, oxalate and malonate were found to be suitable. Since these salts prevented the hydrolysis of aluminium ion as a result of the complex formation, the solution became neutral. Furthermore, the inhibitive effect was considerably enhanced as high as 97%. The mechanisms of these behaviour were also discussed based on the thermodynamic consideration.
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  • Kensaku Matsunami, Katsuhisa Sugimoto
    1990 Volume 39 Issue 9 Pages 467-473
    Published: September 15, 1990
    Released on J-STAGE: October 30, 2009
    JOURNAL FREE ACCESS
    The effect of environmental factors on the corrosion rates of carbon steel in sulfide-containing 20% monoethanoleamine solutions have been examined using weight loss and potentiodynamic polarization tests. Experiments were conducted in solutions with a sulfide concentration of 6000ppm in the pH range of 9-12 and in the temperature range of 333-408K. The corrosion rate of carbon steel increased with decreasing pH value and increasing temperature. Corrosion rates significantly increased at pH values below 11 and at temperatures above 408K. Among several degradation products of amine, hydroxyethyleethylenediamine (HEED) was the most corrosive species for carbon steel. When various corrosive species were simaltaneously added in a test solution, synergistic acceleration of corrosion was recognized. The corrosion rate of carbon steel in such a solution was larger than that in a solution to which single corrosive species was added.
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  • Atsushi Kobayashi, Takeshi Takai, Nobumitsu Kitajima
    1990 Volume 39 Issue 9 Pages 474-478
    Published: September 15, 1990
    Released on J-STAGE: October 30, 2009
    JOURNAL FREE ACCESS
    Several methods of preparing gamma ferric oxyhydroxide (γ-FeOOH) are currently available. But these methods are limited to prepare γ-FeOOH only in small amounts, and not adequate to produce it in the scale of mass production. We have developed a novel method suitable for producing γ-FeOOH in both laboratory scale and industrial scale. This process employs catalytic oxidation of ferrous iron and crystal growth in aqueous solution. The γ-FeOOH prepared by this process has several characteristics different from the conventional ones. The first is the shape of the particle. It has a round form with a diameter of about 2 to 10μm. The second characteristic is the crystallographical feature of the particle. Round particle is composed of many plate-like single crystals which combine spokewise with each other. The particle is in high crystalline state which enables to acquire low contents of the impurities. This product may be used as a standard material in the corrosion research.
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  • Yuko Arai, Takashi Honda
    1990 Volume 39 Issue 9 Pages 479-483
    Published: September 15, 1990
    Released on J-STAGE: October 30, 2009
    JOURNAL FREE ACCESS
    The application of SAW (surface acoustic wave) devices which can generate high frequencies for corrosion monitoring in both gaseous and liquid environments was studied. A 36°-roted Y cut X propergation LiTaO3 (36 LT) which can generates SH (shear horizontal displacement)-SAW was selected for piezoelectric substrate. By using this SAW device sensor with a center frequency of 104MHz, metal dissolution process of aluminum thin film in dilute HCl aqueous solution was monitored at room temperature in real time with a high degree of mass sensitivity (2ng/cm2/Hz). Further, the adsorption process of water on evaporated gold surface could be monitored in the atmospheric environment.
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  • Toshihisa Matsushima
    1990 Volume 39 Issue 9 Pages 484-494
    Published: September 15, 1990
    Released on J-STAGE: October 30, 2009
    JOURNAL FREE ACCESS
    Building equipment is subdivided into three categories: electrical, plumbing and air conditioning equipment. The plumbing equipment is further divided into cold and hot water supplies and drainage system as well as gas supplies, and fire-fighting installations. Depending on its purposes, the plumbing equipment is also subdivided into cooling water supply, chilled water and hot water supplies, the return condensation and the oil supply. In this paper, plumbing and air conditioning equipment related to water use in general is discussed. Because very little research has been conducted on building equipment, the technology nedded to evaluate it is insufficient in many respects compared with industrial plant construction works. The problems of corrosion experienced with building equipment were reported a decade ago. They were: grooving corrosion on electric resistance welded pipes; pitting corrosion and red water on galvanized steel pipes; stress corrosion cracking on stainless hot water tanks; pitting corrosion, corrosion and fatigue cracking on copper pipes for hot water supply; dezincification on brass valves; corrosion on condenser tubes for the refrigeration machine; and macro-cell corrosion on underground pipes. However, problems with building equipment are on the decline because their causes and cures have been clarified and identified in recent years. In this paper, individual cases of corrosion have been examined to determine causes and cures.
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  • Norio Sato
    1990 Volume 39 Issue 9 Pages 495-511
    Published: September 15, 1990
    Released on J-STAGE: October 30, 2009
    JOURNAL FREE ACCESS
    A review is given of some simplified concepts that will contribute to a better understanding of corrosion fundamentals. The corrosion process involves not only electrochemical reactions but also acid-base reactions, and it is the acid-base nature that diversifies the corrosion phenomena. Anions either catalyze or inhibit the anodic metal dissolution, and the passivation will result from the hydroxide-catalyzed mechanism of metal dissolution. Corrosion precipitates frequently control the selective mass transport in corrosion processes. Anion-selective precipitates accelerate and cation-selective precipitates decelerate corrosion propagation. A bipolar precipitate film, if anodically polarized, undergoes deprotonation and turns into a passive film. The electrochemical stability of passivated metals is determined by the electron energy band structure of the passive film. The passive film of n-type semiconducting oxides appears electrochemically more stable than the passive film of p-type semiconducting oxides.
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