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Relationship between Corrosion Form and Elution Behavior of Copper Tubes Surfaces with Different Residual Carbon Amounts

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Materials Sciences and Applications 2022年第12期13卷 595-602页

作者： Yuma Kano itaru ikeda Takashi Iyasu Yuna Yamaguchi Yutaka Yamada Osamu Sakurada Department of Chemistry and Biomolecular Science Faculty of Engineering Gifu University Gifu Japan Dai-Dan Co. Ltd. Saitama Japan Kurita Water Industries Ltd. Tokyo Japan Daiwa Techno Co. Ltd. Gifu Japan

It was well known that residual carbon on the inner surface of copper tubes was a cause of pitting corrosion, and copper tube surfaces with different residual carbon amount were different corrosion forms. In this study, the relation between corrosion form and elution of copper in immersion tests by accelerated corrosion test solutions was examined. Generally, pitting corrosion that occurs in actual machines was reported to observe chloride ion at the bottom of the pitting corrosion of copper tubes. Energy dispersive X-ray (EDX) mapping analysis indicated that chlorine was concentrated in the upper layer of the samples where copper was not detected under conditions of low residual carbon amount, while chlorine was concentrated under part of the micromounds (including the bottom of the pits) under conditions of high residual carbon amount. It was also suggested that the amount of copper eluted was related to the amount of residual carbon.

关键词： Carbon Film Residual Carbon Amount Pitting Corrosion Corrosive Anion The Pitting Corrosion Resistance Test

Evaluation of Expansion Process to Improve Corrosion Resistance of Copper Tubes with High Residual Carbon on the Inner Surface

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Materials Sciences and Applications 2023年第2期14卷 45-52页

Residual carbon on the inner surface of copper tubes is known to be a cause of pitting corrosion. We showed previously that the rapid filling test was useful to evaluate the pitting corrosion resistance of copper tubes. Immersion tests using the rapid evaluation test solution showed that corrosion occurs on the entire surface of copper tubes with low residual carbon amounts, while those with high residual carbon amounts show pitting corrosion. Therefore, it is necessary to improve the corrosion resistance of copper tubes with high residual carbon amount, which are expected to undergo pitting corrosion. As pitting corrosion occurs when anodes are locally concentrated on part of the metal surface, it has been suggested that anodes be dispersed over the entire surface by the processing of the metal surface. Metal processing methods have various purposes, including changing the shape and properties of metals, and in this case, leading to desirable surface properties (such as expansion and drawing processes). Here, we focused on the expansion process and its effects on corrosion resistance of copper tubes. The results showed that hydraulic expansion has a significant effect on the inner copper surface by improving corrosion resistance as the anode area increases.

关键词： Expansion Process Carbon Film Pitting Corrosion Corrosive Anion the Pitting Corrosion Resistance Test

Next-generation regenerative therapy for ischemic stroke using peripheral blood mononuclear cells

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Neural Regeneration Research 2024年第11期19卷 2341-2342页

作者： Masato Kanazawa itaru Ninomiya Yutaka Otsu Masahiro Hatakeyama Department of Neurology Brain Research InstituteNiigata UniversityNiigataJapan

Stroke is the second leading cause of death and the third leading cause of disability worldwide after heart *** predict that stroke deaths and permanent disabilities will increase worldwide by the year ***-target therapies may be insufficient,because ischemic cerebral injury involves several ***-mediated therapies are ideal,because they target multiple cell types to enhance protection and recovery.

关键词： ischemic death cerebral

Quantum Fibrations: Quantum computation on an arbitrary topological space

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Acta Mathematica Sinica,English Series 2024年

作者： Kazuki ikeda Co-design Center for Quantum Advantage (C2QA) & Center For Nuclear Theory Department of Physics and Astronomy Stony Brook University Department of Mathematics and Statistics & Centre for Quantum Topology and Its Applications(quanTA) University of Saskatchewan

Using operator algebras, we extend the theory of quantum computation on a graph to a theory of computation on an arbitrary topological space. Quantum computation is usually implemented on finite discrete sets, and the purpose of this study is to extend this to theories on arbitrary sets. The conventional theory of quantum computers can be viewed as a simplified algebraic geometry theory in which the action of SU (2) is defined on each point of a discrete set. In this study, we extend this in general as a theory of quantum fibrations in which the action of the von Neumann algebra is defined on an arbitrary topological space. The quantum channel is then naturally extended as a net of von Neumann algebras. This allows for a more mathematically rigorous discussion of general theories,including physics and chemistry, which are defined on sets that are not necessarily discrete, from the perspective of quantum computer science.

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Study of Corrosion on Film Properties of High Strength Cu-Sn-Zr Alloys in Tap Water

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Materials Sciences and Applications 2020年第1期11卷 70-80页

作者： itaru ikeda Noriyuki Tanaka Motoki Kuratani Yutaka Yamada Osamu Sakurada Yanagido Gifu-Shi Gifu University Gifu Japan Kitanagai Miyoshi-Machi Iruma-Gun Technical Research Laboratory DAI-DAN Co. Ltd. Saitama Japan

Corrosion has been reported to occur in the copper tubes of heat ex-changers in multiple-circulation hot water supply systems. We have been investigating the applicability of high-strength Cu-0.65 mass% Sn-0.014 mass% Zr-0.020 mass% P alloy to counteract this corrosion. Immersion tests, electrochemical measurements, and field tests were performed. Excellent corrosion resistance of the alloy was established under conditions with flowing water due to the formation of composite films containing tin. The alloy is expected to be better than copper as a corrosion-resistant material for heat exchanger tubes.

关键词： Cu-Sn-Zr Alloy Corrosion Resistance Heat Exchanger Hot Water Supply System Flow Condition

A Study of Water Treatment Chemical Effects on Type I” Pitting Corrosion of Copper Tubes

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Materials Sciences and Applications 2020年第7期11卷 494-504页

作者： Takashi Iyasu Motoki Kuratani itaru ikeda Noriyuki Tanaka Yutaka Yamada Osamu Sakurada Technical Support Department Kurita Water Industries Ltd. Tochigi Japan Gifu University Gifu Japan Technical Research Laboratory DAI-DAN Co. Ltd. Saitama Japan

It is known that one of the causes of pitting corrosion of copper tubes is residual carbon on the inner surface. It was confirmed that type I” pitting corrosion of the copper tube is suppressed by keeping the residual carbon amount at 2 mg/m2 or less, which is lower than that of the type I’ pitting corrosion, or by removing the fine particles that are the corrosion product of galvanized steel pipes. The developed water treatment chemical was evaluated using three types of copper tubes with residual carbon amounts of 0 mg/m2, 0.5 mg/m2, and 6.1 mg/m2. The evaluation was conducted for three months in an open-circulation cooling water system and compared with the current water treatment chemical. Under the current water treatment chemical conditions, only the copper tube with a residual carbon amount of 6.1 mg/m2 showed a significant increase in the natural corrosion potential after two weeks, and pitting corrosion occurred. No pitting corrosion and no increase in the natural corrosion potential were observed in any of the copper tubes that were treated with the developed water treatment chemical. In addition, the polarization curve was measured using the cooling water from this field test, and the anodic polarization of two cooling waters was compared. For copper tubes with a large amount of residual carbon, the current density near 0 mV vs. Ag/AgCl electrode (SSE) increased when the developed water treatment chemical was added.

关键词： Copper Tube Pitting Corrosion Residual Carbon Cooling Water System Water Treatment

Simple Measurement of Carbon Films on Copper Tubes and Their Effects on Corrosion

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Open Journal of Composite Materials 2021年第1期11卷 12-22页

It has been reported that pitting corrosion in copper tubes occurs due to the effect of a carbon film produced by the influence of undergoing an oil and heat treatment. As a quantitative method for determining the residual carbon amount, it has been reported that the inner surface of a copper tube can be dissolved with a mixed acid to collect and analyze the adhering carbon;however, this method is dangerous and difficult. Therefore, two methods were examined as a simple quantitative method for obtaining the residual carbon amount using copper tubes with known residual carbon amounts. One method utilizes X-ray photoelectron spectroscopy (XPS), and the other method utilizes the potential difference between the carbon film-adhered surface and carbon film-removed surface. In regard to XPS measurement, a linear correlation was found between the spectral intensity of C and the residual carbon amount;therefore, XPS measurements were considered to be effective as a simple measurement method for the carbon film on the inner surface of a copper tube. In the evaluation method by measuring the corrosion potential, a correlation was observed between the potential difference ΔE and the residual carbon amount of the inner surface of the tube and the outer surface of the polished tube. It is considered possible to estimate the residual carbon amount from the prepared calibration curve. Through these studies, it is suggested that the carbon film was non-uniformly present on the surface of the copper tube. Therefore, the galvanic current was measured, and the effect of a non-uniform carbon film on corrosion behavior was investigated. As a result, in the measurement of galvanic current, the current flowed from the copper tube with a large amount of residual carbon (cathode) to the copper tube with a small amount of residual carbon (anode). In addition, the higher the area ratio of the carbon film was, the larger the galvanic current tended to be.

关键词： Copper Tube Residual Carbon Pitting Corrosion Cooling Water System Re-frigerator XPS

Effect of Pipe Diameter on Electrochemical Behavior of Stainless Steel Type 304 Pipes in Tap Water

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Materials Sciences and Applications 2019年第11期10卷 697-708页

作者： Noriyuki Tanaka Shigeru Sato itaru ikeda Tadahiko Uchida Motoki Kuratani Yutaka Yamada Osamu Sakurada Technical Research Laboratory DAI-DAN Co. Ltd. Saitama Japan Gifu University Gifu Japan

We investigated the effects of pipe diameter on the corrosion resistance of stainless steel type 304 pipes using electrochemical measurements. Compared to plate steel, pipes have harder physical properties and tend to be harder and showed greater permeability with decreasing inner diameter. We found that the maximum corrosion current density in the secondary active state, which is the starting point of secondary passivation, appeared in the polarization curve measurement in tap water. Similar to the Vickers hardness and the maximum current density in the secondary active state, the permeability tended to increase as the diameter decreased. This is thought to increase the amount of deformation-induced martensitic and increase corrosion susceptibility. The peak of the secondary active current density was clearly seen as the potential sweep speed was increased. In addition, potential sweep speed dependence was observed in the corrosion susceptibility evaluation of deformation-induced martensite. In comparison with acid treatment, the formation of deformation-induced martensite was considered to occur in the extreme surface layer. The maximum corrosion current density in the secondary active state is expected to be a new susceptibility evaluation method for evaluating the deformation-induced martensitic transformation.

关键词： Stainless Steel Type 304 Electrochemical Consideration Pipe Diameter Electrochemical Behavior Tap Water

Exploring the effect of cooling rate on non-isothermal crystallization of copolymer polypropylene by fast scanning calorimetry

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China Foundry 2024年第4期21卷 379-386页

作者： Yang Liao Ye-yuan Hu Kosuke ikeda Ryoji Okabe Rui-fen Wu Ryota Ozaki Qing-yan Xu Key Laboratory for Advanced Materials Processing Technology School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China Composite Laboratory Research&Innovation Center Mitsubishi Heavy Industries Ltd.Nagasaki 8510392Japan

Polypropylene is commonly used as a binder for ceramic injection molding,and rapid cooling is often encountered during ***,the crystallization behavior of polypropylene shows a strong dependence on cooling rate due to its semi-crystalline ***,the influence of cooling rate on the quality of final product cannot be *** this study,the fast differential scanning calorimetry(FSC)test was performed to study the influence of cooling rate on the non-isothermal crystallization behavior and non-isothermal crystallization kinetics of a copolymer polypropylene(PP BC03B).The results show that the crystallization temperatures and crystallinity decrease as the cooling rate *** addition,two exothermic peaks occur when cooling rate ranges from 30 to 300 K·s^(-1),indicating the formation of another crystal ***,Ozawa and Mo equations were used to explore the non-isothermal crystallization kinetics,and it can be concluded that the Mo method is suitable for this study.

关键词： cooling rate crystallization temperature crystallinity non-isothermal crystallization kinetics FSC copolymer polypropylene