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Page : 527 - 537
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- Measurement of Levels of Dross Intermetallic Particles in 55%Al-Zn Alloy Based Metal Coating Bath by Pressure Filtration Technique
- A pressure filtration technique was used to measure levels of dross intermetallic compound particles (IMCs) to assess overall metal cleanliness of 55%Al-Zn alloy-based metal coating bath. The weight of molten metal passing through a micro-filter was measured at constant pressure and temperature using a Prefil-Footprinter, a portable inclusion analyser. Fundamental cake filtration theory was applied to analyse Prefil data. Inverse average filtration rate (t/V) and dt/dV was plotted as a function of cumulative filtrate vol-
ume (V ) to generate filtrations curves. Cake mode filtration parameters were determined from linearized plots of a constant pressure filtration equation (t/V=μαavC/2A2ΔP+μRm/APΔ) The linear diagram in the dt/dV form was used to assess deviations due to secondary effects. The IMC mass captured/unit volume of filtrate was calculated based on chemical analysis of the filter cake and standard cake mode filtration parameters. Detailed microstructural analysis was carried out to characterize the nature of IMCs captured in the filter cake. Fundamental cake fil- tration theory together with microstructural analysis of the filter cake can provide a quantitative measure for lev- els of IMCs present in the bath and overall metal cleanliness of the coating bath. - KEYWORDs : Pressure-filtration, Filter-cake, IMCs, Specific cake resistance, Filtration curve
- AUTHORs : Nega Setargew†, Greg Harris, Uyen Kieu, Nghia Truong, and Jaka Prakasha
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Page : 538 - 545
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- Study on Characteristics and Mechanism of Blackening Behavior Under Anti-Fingerprint Coatings of Al-Zn-Mg Coated Steel Sheet
- Fingerprint resistant sheets with a substrate of 55%Al-Zn-Mg coated steel are prone to blackening under service environment. In this study, the chromatic aberration of each 55%Al-Zn-Mg coated steel sheet sample was characterized with a colorimeter. Corrosion morphologies and chemical compositions of blackening samples were observed with a scanning electron microscope coupled with an energy dispersive spectroscope (SEM-EDS). Corrosion products generated from different alloy phases of the Al-Zn-Mg coating were analyzed by micro-Raman spectroscopy. The black area of the blackened sample formed corrosion products including needle shaped products Zn5(OH)6(CO3)2?H2O and spherical corrosion products Al(OH)3. In addition, the blackening mechanism of the Al-Zn-Mg coating was thoroughly discussed based on scanning Kelvin probe force microscopy (SKPFM) results. The MgZn2 phase and the Zn-rich phase in the Al-Zn-Mg coating had lower Volta potentials than the Al-rich phase in neutral electrolytes. This might have preferentially corroded the anode of corrosion micro-cells. The resulting corrosion products under- neath the anti-fingerprint coating finally induced the blackening phenomenon.
- KEYWORDs : 55%Al-Zn-Mg coated steel, Anti-fingerprint coating, Blackening behavior, Underneath corrosion, Volta potential
- AUTHORs : Yuling Ren†, Lin Lu, Kai Wang, Chuanhua Lin, Xinyan Jin, and Hongwei Qian
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Page : 546 - 555
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- Enhanced Fe-Al Interfacial Reaction in Hot-Dip Zn-Al-Mg Alloy-Coated Steel by Adding Si to the Molten Bath
- This study investigated the impact of Si addition on Al-Fe intermetallic layer formation and growth in a Zn-6%Al -3%Mg coating bath. The presence of trace amount of Si in the bath created a continuous η-Fe2Al5 layer at the Fe/coating interface at a low bath temperature, while an incomplete θ-Fe4Al13 layer was formed with almost no Si added. It is widely acknowledged that Si atoms can fill vacancies along the caxis of the orthorhombic Fe2Al5 unit cell, preventing Al diffusion and impeding the growth of Fe2Al5. The presence of Fe2Al5 containing Si can also suppress Fe dissolution. Findings of this study suggest that the addition of Si may promote the dissolution of Fe in the initial stage of Fe-Al reaction and provide a strong driving force for η phase formation at the substrate/bath interface. Therefore, with a small amount of Si added to a galvanized bath with a composition close to the eutectic point, a lower bath temperature can be used while still ensuring good Fe/coating adhesion.
- KEYWORDs : Silicon, Interfacial reaction, Intermetallic layer, Fe2Al5, Fe4Al13
- AUTHORs : Yuanyuan Yan†, Guangxin Wu, Yiming Chen, Jingge Dai, Wentao Zhang, Xianlu Meng, Yuling Ren, Chuanhua Lin, Shanqing Li, and Junfei Wang
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Page : 556 - 561
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- Antiviral Steel Sheets Effective Against SARS-CoV-2
- In recent years, the awareness of infection prevention has increased owing to the spread of the novel coronavirus disease 2019. Antiviral products are necessary to avoid the risk of infection from existing and new SARS-CoV-2 variants. There is a growing need to impart antiviral properties to applications involv- ing human contact. Therefore, antiviral steel sheets with a visible-light-responsive photocatalyst in the surface layer were developed in this study with intended applications on office furniture and interior fin- ishing of buildings frequently touched by numerous people. The antiviral effect was investigated using a non-enveloped bacteriophage Q-beta (lipid bilayer membrane) and an enveloped SARS-CoV-2. A series of antiviral tests were conducted in compliance with JIS R 1756:2020 or by applying mutatis mutandis. Resistance of these antiviral steel sheets to sunlight was also investigated. These antiviral steel sheets developed in this study exhibited fingerprint resistance, formability, and antiviral properties. These sheets were also durable under exposure to sunshine. Thus, they can be used as an effective tool to reduce the risk of SARS-CoV-2 infection.
- KEYWORDs : Antiviral, Photocatalyst, Visible light responsibility, Steel sheet, SARS-CoV-2
- AUTHORs : Fumio Shibao†
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Page : 562 - 568
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- Corrosion Protection of Electrogalvanized Steel Sheet by Chromate-free Coating with Tetravalent Vanadium Ions
- The corrosion-protective behavior of electrogalvanized steel sheets (EG) by tetravalent vanadium ions was investigated. The immersion of bare EG in a NaCl solution revealed that the cathodic reactivity to form vanadium (III) oxide on the EG surface decreased when vanadium (IV) oxide sulfate was added to the solution. Characterization of the corrosion products by X-ray photoelectron spectroscopy revealed that vanadium (III) precipitated as V2O3 on the EG surface, while ZnO was also included in the corrosion products. It was assumed that vanadium (IV) species was reduced to vanadium (III) simultaneously with the oxidation of zinc, and V2O3 precipitates immediately on the EG surface. The corrosion-protective ability of an epoxy coating containing vanadium (IV) species was investigated by a salt spray test. The white rust area of EG coated with vanadium (IV) species was smaller than that without vanadium (IV). Since the reduction reaction of vanadium (IV) species followed by the precipitation of V2O3, which has a high corrosion protection ability, indicated a corrosion-protective process similar to that of chromium (VI) ions, vanadium (IV) species was concluded as a candidate inhibitor for chromate-free coatings.
- KEYWORDs : Corrosion protection, Vanadium (IV) ion, Electrogalvanized steel sheet, Epoxy coating
- AUTHORs : Takeshi Matsuda†, Shinichi Furuya, Rie Kaneko, and Koji Fushimi
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Page : 569 - 577
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- 다양한 코팅기술이 적용된 탄소강의 기계적 가공에 따른 부식저항성 연구
- This study compared and analyzed the electrochemical properties of the galfan+Top coating, which demonstrated excellent corrosion resistance in previous research, against the widely used gal- valume+Cr3+coating during bending processes (U type). Results from the potentiodynamic polarization experiment showed that the corrosion current densities for the galfan+Top-coated specimen and the gal- valume+Cr3+-coated specimen were 0.041 and 0.081 ?A/cm², respectively, indicating that the galfan+Top coating exhibited superior corrosion resistance. However, the corrosion resistance trends observed through 3D microscopy, SEM surface analysis and EDS analysis did not align with the results from the potentio- dynamic polarization experiment. This discrepancy was attributed to the transpassive behavior of the gal- fan+Top-coated specimen, where the current density increased from ?0.407 V until the end of the potentiodynamic polarization experiment, which was not seen in the galvalume+Cr3+-coated specimen. After conducting the galvanostatic corrosion experiment, minimal differences in corrosion resistance were noted through SEM surface analysis and EDS analysis. Nevertheless, 3D microscopy analysis revealed less surface damage on the galfan+Top-coated specimen compared to the galvalume+Cr3+-coated specimen, highlighting a difference in corrosion resistance.
- KEYWORDs : Carbon steel, Galfan coating, Galvalume coating, Trivalent chromium, Polymer coating, Corrosion resistance
- AUTHORs : 현광룡 · 신동호 · 황현규 · 김성종†
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Page : 578 - 586
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- 암모니아 환경에서 선박 엔진용 고무 소재의 열화 특성 및 영구압축줄음율 평가
- Global climate change is already underway, leading to extreme weather events such as rising sea levels, severe cold snaps, and heat waves. These changes pose significant threats to human civilization, including the emergence of new infectious diseases and disruptions to economic activities. In response, the Inter- national Maritime Organization (IMO) has proposed a carbon-neutral policy that aims to prohibit the use of carbon-based fuels by 2050. For future ship fuel compositions, there will be a decline in the use of fossil fuels and a corresponding increase in the adoption of ammonia as a fuel source. This study evaluated dura- bility of O-ring materials known to be as critical as metal components in ship engines and related systems under ammonia-rich environments. Various rubber materials commonly used for O-rings in ship engines and equipment were tested for durability in a 99.5% ammonia environment. Results suggest that some EPDM and FFKM materials might be suitable for such applications. However, the applicability of rubber materials cannot be determined solely based on simple chemical reaction characteristics. Reliable data can only be secured by simulating and replicating actual operating conditions in which such materials are used.
- KEYWORDs : Ammonia, Compression set, Rubber materials, Net Zero, Greenhouse gas
- AUTHORs : 임성진 · 박진영 · 이승준†
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Page : 587 - 595
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- 3D 모델링을 이용한 매설배관 결함 위치에 따른 전위구배 영향 분석
- The management process for buried pipelines typically follows a sequence that includes pre-assessment, indirect inspection, direct inspection, and post-assessment. One widely used method for detecting coating defects during the indirect inspection phase is Direct Current Voltage Gradient (DCVG). This method mea- sures the potential gradient created when current flows through areas with damaged coatings. While DCVG is highly accurate for detecting defects in single pipelines, such as gas or oil pipelines, its effec- tiveness diminishes in situations where pipelines cross or are layered. In this study, we analyzed the DCVG signals and potential gradient trends in scenarios involving multiple defects in either single or crossed pipelines, utilizing 3D modeling techniques. We first validated the reliability of our 3D model by com- paring the measured values from a mock-up test site with actual buried pipelines against the modeled val- ues. Subsequently, we assessed the model\'s reliability and examined the potential gradient distribution based on defect locations, particularly in cases involving crossed pipelines.
- KEYWORDs : Buried pipe, Cathodic protection, Potential gradient, DCVG (Direct Current Voltage Gradient), 3D Modeling
- AUTHORs : 김기태† · 임부택 · 장현영 · 유영란 · 최승헌 · 김영식 · 이대영
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Page : 596 - 623
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- Oxazoles: A Promising Frontier in Corrosion Inhibition for Steel in Acidic Environments
- Steel corrosion in an acidic environment is a serious problem in various sectors of the economy. It must be controlled by developing an effective corrosion protection plan. In this review, oxazole derivatives as iron inhibitors in acid solutions are summarized. Corrosion in acids and corrosion inhibition of steel as a means of controlling corrosion are described first. The possibility of oxazole derivatives being corrosion inhib- itors are then introduced. Details about the means by which oxazole derivatives can prevent corrosion of metals are explained. Classical methods and the latest trends in the synthesis of new oxazole’s are described, especially the journey of obtaining oxazole derivatives. Laboratory investigations focusing on oxazoles\' inhibition effects, factors affecting their efficiencies, and comparative analyses with other inhib- itors are then discussed. Industrial applications of oxdazols as corrosion inhibitors by oil and gas, chemical processing, automotive, marine water treatment industries are also discussed. Concerns and possibilities of future studies and how oxazoles could be exploited for corrosion resistance will extend our knowledge of corrosion within the scientific community. This study demonstrates the potential of oxazoles as corrosion inhibitors and their importance. It provides new ideas for improving corrosion treatment of steel in acidic environments.
- KEYWORDs : Oxazoles, Corrosion inhibition, Steel, Acidic environments, Mechanisms
- AUTHORs : A. Y. I. Rubaye†, K.Z. Abdulsada, Adil A. Al-Fregi, R.K. Zaidan, A. A. Alamiery, and A. A. H. Kadhum
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Page : 1 - 10
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- Comparative Study of Corrosion Behavior of AA6061 and AA5086 Aluminum Alloys in Polluted Local Seawater -Iraq
- This study investigated the electrochemical corrosion performance of AA6061 and AA5086 alloys in local seawater (LSW) at both low and high temperatures, reflective of conditions in the Iraqi environment. An electrochemical technique was employed to assess the corrosion behavior of the alloys in locally polluted seawater and a 3.5 wt% NaCl solution. The specimens were tested at various temperatures (5, 15, 25, 35, 45, and 55 oC) and compared to a 3.5 wt% NaCl solution at room temperature. Optical, microscopic, and SEM tests were conducted on the corroded surfaces. The results revealed that the corrosion rate increased with temperature, and there was a noticeable increase in the depth and distribution of pitting as temperature rose. Generally, the pitting potential (Ep) values for AA5085 were higher than those for AA6061 alloys. Although the corrosion current densities for AA5086 and AA6061 in the NaCl solution were similar (0.26 and 0.2 mA/cm2, respectively), AA6061 exhibited a six-fold lower electrochemical corrosion current density compared to AA5086 at 25 oC in locally polluted seawater (LSW).
- KEYWORDs : Local Seawater (LSW), AA5086, AA6061, Electrochemical corrosion
- AUTHORs : Mohanad Muzahem Khalaf, Al-Ezzi Salih, Taha H. Abood Al-Saadi, and A. M. Mustafa†
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