• Title/Summary/Keyword: Hot-dip Galvanized

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Effects of Zinc and Aluminum Hot-dip Galvanized Sheet Steel on the Gill and Hepatopancreas of the Abalone Haliotis discus hannai (아연 및 알루미늄 용융도금 처리된 강판이 북방전복(Haliotis discus hannai)의 아가미와 간췌장에 미치는 영향)

  • Lee, Chi Hoon;Park, Jun Young;Lee, Young Don
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.50 no.4
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    • pp.388-395
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    • 2017
  • We investigated the toxicity of zinc and aluminum hot-dip galvanized sheet steel to abalone Haliotis discus hannai via changes in the gill and hepatopancreas using histological and transmission electron microscopy analysis. Experimental groups were composed of one control and four exposure conditions (direct or indirect exposure to zinc and aluminum hot-dip galvanized sheet steel). In the control group, aluminum exposure groups (direct and indirect), and indirect zinc exposure group, abalone mortality was not observed until the end of the experiment, and no histopathological changes were observed in the gill and hepatopancreas. However, the direct zinc exposure group exhibited 100% mortality. Ultrastructural analysis of the cytoplasm of ciliated and microvilli-bearing epithelial cells from gill filaments revealed electron-dense vesicles near the cell membrane and disruption of the nuclear membrane. We also observed swollen mitochondria and a loss of mitochondrial cristae. The hepatopancreas showed similar changes, and we detected highly electron-dense particles within the vesicles. These results suggest that abalone exposed directly to zinc hot-dip galvanized sheet steel experience acute toxicity, causing damage to cell organelles in the gill and hepatopancreas and, finally, inducing mortality.

A Study on the Developmentment of Zero-spangle Hot Dip Galvanized Steel Sheets with High Brightness and Corrosion Resistance (고광택 고내식 용융아연도금 제로스팡글 개발에 관한 연구)

  • 진영구;김흥윤
    • Journal of the Korean institute of surface engineering
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    • v.29 no.4
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    • pp.253-260
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    • 1996
  • Regular spangle hot dip galvanized steel sheets were made in the zinc bath containing a small amount of Al and with the addition of Pb, Sb, Sb-Mg, Sb-Cu and Bi respectively whose average glosses were measured. Zero-spangle hot dip galvanized steel sheets were also made by spraying a 2% $NH_4H_2PO_4$ solution on molten coating surfaces with exactly the same chemical compositions as above used for regular spangle and whose glosses and corrosion losses were also evaluated. For manufacturing zero- spangle hot dip galvanized steel sheets with high brightness, the zinc bath with 0.02%Sb and the spraying of a 2% $NH_4H_2PO_4$ solution were proposed and for better brightness and corrosion resistance, the zinc bath with 0.02% Sb-0.50%Mg and the spraying of a 2% $NH_4H_2PO_4$ solution were also proposed.

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Improvement of Coating Adherence of Hot-dip Galvanized Sheet Steels (용융아연 도금강판의 도금밀착성 개선)

  • 김종상;배대철
    • Journal of the Korean institute of surface engineering
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    • v.24 no.1
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    • pp.18-24
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    • 1991
  • In the present work the adhesion failure of a hot-dip galvanized coating has been studied as a function gas composition temperature of strip and of atmospheric gas in furnace. The adhesion failure of the hot-dip galvani-zed coating is classified as three mechanisms : carbon deposition, oxide film formation and alloy layer formation. The adhesion failure due to oxide film formation decreased markedly by increasing the gases temperature of direct fired furnace(DFF) in order to improve the reducing ability of steel strip. Optimum conditions of operating and manufacturing facilities for improving the coating adherence are suggested by analyzing the interface between steel substrate and coating layer.

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Benchmarking of Zinc Coatings for Corrosion Protection: A Detailed Characterization of Corrosion and Electrochemical Properties of Zinc Coatings

  • Wijesinghe, Sudesh L;Zixi, Tan
    • Corrosion Science and Technology
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    • v.16 no.1
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    • pp.38-47
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    • 2017
  • Due to various types of Zn coatings for many decades for various applications, it is imperative to study and compare their corrosion resistance properties of some of these. Here, we introduce a systematic methodology for evaluation and validation of corrosion protection properties of metallic coatings. According to this methodology, samples are were exposed in an advanced cyclic corrosion test chamber according to ISO 14993, and removed at the end of each withdrawal for respective corrosion and electrochemical characterization to evaluate both barrier and galvanic protection properties. Corrosion protection properties of coatings were evaluated by visual examination according to ISO 10289, mass loss and subsequent corrosion rate measurements, electrochemical properties, and advanced electrochemical scanning techniques. In this study, corrosion protection properties of a commercial zinc rich coating (ZRC) on AISI 1020 mild steel substrates were evaluated and benchmarked against hot dip galvanized (HDG). Results were correlated, and corrosion protection capabilities of the two coatings were compared. The zinc rich coating performed better than hot dip galvanized coating in terms of overall corrosion protection properties, according to the exposure and experimental conditions used in this study. It proved to be a suitable candidate to replace hot dip galvanized coatings for desired applications.

New Corrosion-Resistant Zn-Al-Mg Alloy Hot-Dip Galvanized Steel Sheet

  • Kohei Tokuda;Yasuto Goto;Mamoru Saito;Hiroshi Takebayashi;Takeshi Konishi;Yuto Fukuda;Fumiaki Nakamura;Koji Kawanishi;Kohei Ueda;Hidetoshi Shindo
    • Corrosion Science and Technology
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    • v.23 no.2
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    • pp.121-130
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    • 2024
  • In recent years, Zn-Al-Mg alloy galvanized steel sheets have been widely used as coated steel sheets to support social capital in the infrastructure field. A feature of Zn-Al-Mg alloy-coated steel sheets is that they provide a better corrosion protection period than Zn-coated steel sheets. In this study, the corrosion resistance of a new Zn-Al-Mg alloy-coated steel sheet was investigated and compared to that of conventional commercially available coated steel sheets. The investigation confirmed that increasing the Mg concentration in the Zn-Al-Mg-coated steel sheet improved corrosion resistance, which was more than 10 times that of the galvanized steel sheet specified in JIS G 3302. The study findings also confirmed that the corrosion resistance reached more than twice that of the coated steel sheet specified in JIS G 3323. If such galvanized steel sheets are applied to social infrastructures that are exposed to severely corrosive environments, the service life of the infrastructure might be extended.

A Study on Detecting Dross in Coating Layer on Hot-dip Galvanizing Steels (용융아연 도금강판의 도금층에 잔류한 드로스 검출에 관한 연구)

  • 김유철;이호종
    • Journal of the Korean institute of surface engineering
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    • v.36 no.6
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    • pp.466-474
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    • 2003
  • To develop a method of detecting dross in coating layer on hot-dip galvanizing steel, chemical etching behavior of the artificial coating layers with top and bottom dross were investigated. After chemical etching with the mixture of picric acid and sodium thiosulfate, each of the top and bottom dross take its distinct color, and alloy layer in coating is also observed. Defects in the coating layers of HGI(hot rolled galvanized iron), CGI(continuous galvanized steel sheet) and GA(galvannealed steel) were analysed, and methods of dross detection which can be applied to inspection process in manufacture were suggested.