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Page : 21 - 27
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- 건식 및 습식 염소가스 환경에서 노출된 반도체 공정용 316L 스테인리스강의 부식 특성 평가
- This study investigated corrosion behavior of 316L stainless steel exposed to chlorine gas (Cl2gas) in dry and wet environments at room temperature. Experiments were conducted over 14 days using both electropolished and non-electropolished specimens to evaluate effects of surface treatment and environmental conditions on corrosion. The extent of corrosion was evaluated by measuring weight change and corrosion rate (mm/year). Surface morphology, cross-section almorphology, and corrosion layer were analyzed using SEM/EDS map-
ping. The non-electropolished specimens formed a corrosion layer more than 7 μm thick, composed of Fe, Cr, Cl, and O. Electropolished specimens maintained a pristine surface with no formation of a corrosion layer. Weight measurements indicated that non-electropolished specimens experienced a weight change of 5.44 mg/cm2 in wet conditions, which was over four times higher than that observed in dry conditions. In contrast, electropolished spec- imens demonstrated exceptional corrosion resistance due to a stable Cr oxide layer, showing a minimal weight change of less than 0.01 mg/cm regardless of moisture presence. - KEYWORDs : 316L Stainless steel, Corrosion, Chlorine gas, Electropolishing, Semiconductor industry
- AUTHORs : 정우철 · 한덕현 · 공만식†
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Page : 11 - 20
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- Coating Technology to Improve the Performance of Resistance Welding Electrodes for Zn-Mg-Al Alloying Coated Steel Sheets
- PosMAC (POSCO Magnesium Aluminum alloy Coating product) is a ternary alloy-coated steel (Zn- 3%Mg-2.5%Al) developed by POSCO utilizing proprietary technology to achieve high corrosion resis- tance. However, the weldability of PosMAC is lower than that of standard steel sheets due to reactions between Cu-based electrodes and the coated layer during resistance welding. This interaction leads to the formation and growth of CuZn compounds, which causes uneven wear on the electrodes and shortens their lifespan. In this study, we produced the coating using the High Velocity Oxygen Fuel (HVOF) process with various types of WC-based powders. We evaluated both coated and uncoated electrodes by measuring frac- ture strength at 100 spot points after spot welding. Additionally, we assessed the final coating electrode through projection resistance welding at a dual fan component manufacturer. The HVOF-sprayed WC- 12Co coating demonstrated promising results in both spot and projection resistance welding tests. Notably, in projection welding tests with the coated electrode, its lifespan was found to be ten times longer than that of the commercially available uncoated electrode.
- KEYWORDs : Coated steel sheet, HVOF coating, Projection welding, Spot welding, WC-based powder
- AUTHORs : SangHoon Yoon† and Gyuyeol Bae
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Page : 28 - 33
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- 고농도 염소 가스 환경에서의 합금 종류에 따른 부식 거동 연구
- High-concentration chlorine (Cl2) gas is widely used in industries such as chemical processing, pharmaceuticals, electronics manufacturing, and gas treatment. Due to its highly reactive nature, it can also accelerate material degradation, leading to reduced equipment durability and increased maintenance costs. Understanding the corrosion behavior of different alloys in Cl2 environments is crucial for enhancing process stability and extending equipment lifespan. This study analyzed corrosion behaviors of Co-Ni-Cr, Co-Cr-Ni, Fe-Cr-Ni, Cu, and Zn-Al-Cu alloys in high-concentration Cl2 gas environments. Results revealed that Co-Ni-Cr and Co-Cr-Ni alloys exhibited superior corrosion resistance due to formation of stable Cr2O3 protective layers, whereas Fe-Cr-Ni alloys provided intermediate resistance. Cu and Zn-Al-Cu alloys showed varying corrosion behaviors depending on environmental factors such as humidity and oxide layer stability. These findings emphasize the critical role of alloy composition and protective oxide layers in reducing Cl2-induced corrosion. By providing a comprehensive analysis of different alloy systems, this study provides insights into optimizing material selection for Cl2 gas applications, contributing to improved industrial process stability and enhanced durability.
- KEYWORDs : Chlorine gas, Moisture effect, Co-Cr-Ni, Co-Ni-Cr, Gas Corrosion
- AUTHORs : 한덕현 · 정우철 · 공만식†
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Page : 34 - 44
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- 치과용 파일의 EDTA용액에서 코팅물질에 따른 피로파절 표면
- It is important to improve fatigue fracture characteristics when using dental Ni-Ti files in EDTA solution clinically. This is necessary to prevent fracture during a treatment process such as a root canal. To improve this problem, fatigue fractured surface of dental file in EDTA solution with different coating materials was investigated. In the non-coated case, there were mechanical defects. However, when DLC was used for coating, the surface roughness was reduced. In the case of TiN coating, the surface roughness was reduced compared to that of TiAlN coating. Elements constituting the coating film were uniformly detected on the coated surface. The hardness of the DLC coating film was the highest. The elastic modulus of the DLC coating film was lower than that of TiAlN or TiN. TiN showed the best adhesion of the coating film while DLC showed the lowest. In the EDTA solution, DLC showed small bending deformation, while TiAlN and TiN showed large bending deformation. In the clinical fracture test, the time until fracture was the shortest for the non-coated case and the longest for the DLC coating. The coated file showed a reduced wall frac- ture area and fatigue striation compared to the non-coated specimen.
- KEYWORDs : Ni-Ti file, Coating materials, EDTA solution, Fatigue fractured surface
- AUTHORs : 최한철† · 김수찬 · 박선영
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Page : 45 - 50
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- 고Mn강 후판 주조재의 제조공정 중 표면결함 원인 규명
- This study aimed to investigate origins of surface defects observed in high-Mn steel casting slabs after heat treatment conducted at 1170 oC for 2 h and provide insights into their mitigation strategies. The grinding process resulted in the formation of a surface-deformed area composed of a recrystallized fine-grain layer and multiple metal flows. Cross-sectional observations and analyses employing field-emission scanning electron microscopy and energy-dispersive spectroscopy revealed that the occurrence of surface defects was due to internal oxidation with a penetrating form along coarse grain boundaries. Based on oxidation of pre-corroded steel samples during the initial stage, it was found that internal oxidation was initiated at (Fe, Mn)-based corrosion products formed during the pre-corrosion process. This process facilitated deep oxy- gen penetration along Mn- and Cr-enriched grain boundaries, exacerbating surface degradation. These findings indicate that controlling corrosion during manufacturing of high Mn-based steel casting plate, par- ticularly prior to heat treatment, is essential for suppressing surface defects.
- KEYWORDs : High Mn steel, Casting plate, Surface defect, Corrosion, Oxidation
- AUTHORs : 박진성 · 강명훈 · 김성진†
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Page : 51 - 62
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- Improvement of Corrosion Resistance of Stainless Steel 316 by Electroless Phosphorus Nickel-Titania Composite Coating
- To enhance the functional performance of steel components in industrial and consumer applications, it is essential to address challenges such as corrosion susceptibility, environmental toxicity, and surface aes- thetics. Consequently, electroless nickel-phosphorus (Ni-P) coatings on 316 stainless steel substrates have gained considerable attention. This study explores the deposition of low-phosphorus Ni-P coatings incor- porated with titania (TiO2) particles, with sizes ranging from 10 to 30 ?m. Coating solutions were formu- lated with TiO2 concentrations of 0, 5, and 10 g/L, and deposition durations were set at 30 and 60 minutes. The coated samples were systematically evaluated using coating thickness measurements, surface rough- ness analysis, Vickers hardness testing, energy dispersive spectroscopy (EDS), scanning electron micros- copy (SEM), and potentiodynamic polarization testing in 3.5% NaCl solution. Results revealed that the inclusion of TiO2 particles significantly enhanced the mechanical performance of the coatings, as evi- denced by increased hardness values compared to both the bare substrate and TiO2-free Ni-P coatings. Additionally, electrochemical analysis indicated a marked improvement in corrosion resistance, with the TiO₂-reinforced coating achieving a 74% reduction in corrosion rate relative to the uncoated steel. These findings suggest that TiO2-doped electroless Ni-P coatings are a promising solution for advanced surface engineering applications.
- KEYWORDs : Electroless, Nickel-phosphor, Titania particles, Composite nickel coating
- AUTHORs : Nabaa S. Radhi, Farah Sami Rasheed, Zainab Al-Khafaji†, Kulthoom Obaid Ali, and Rasha Ghazi
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Page : 63 - 75
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- Effect of Combining Moringa oleifera and Datura stramonium Extracts as a Green Corrosion Inhibitor for Mild Steel
- The present investigation explores the effect of combining extracts from Moringa oleifera and Datura stra- monium as an eco-friendly corrosion inhibitor for carbon steel in acidic media. The corrosion inhibition effi- cacy was systematically evaluated through gravimetric analysis and electrochemical techniques. The results reveal that Moringa oleifera exhibits the highest corrosion inhibition efficiency of 93.48%, followed by the combination of both plant extracts, which demonstrates superior protective performance compared to Datura stramonium alone consisting of 250 ppm Moringa oleifera leaf extract (MOLE) + 250 ppm Datura stramo- nium leaf extract (DSLE) at 60 °C, achieved an inhibition efficiency of 84.71%. Although slightly lower than the performance of MOLE alone, this result highlights the dominant contribution of MOLE within the blend and underscores its ability to enhance the protective effect of DSLE. This formulation enables the valoriza- tion of the otherwise toxic Datura stramonium by integrating it into a functional, eco-friendly corrosion inhib- itor system. Surface characterization techniques corroborated the formation of a protective adsorbed film on the carbon steel substrate. The enhanced performance is postulated to arise from the combination effect between the diverse phytochemical constituents present in Moringa oleifera and Datura stramonium, which augment the adsorption kinetics and film-forming capabilities.
- KEYWORDs : Corrosion, Moringa oleifera, Datura stramonium, Green Inhibitors, Carbon Steel
- AUTHORs : Hadjer Didouh† , Mohammed Sadou, Rami K. Suleiman, and Mohammed Hadj Meliani
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Page : 76 - 85
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- Towards High Speed Galvanizing ? Mastering Wiping Conditions Using Hydrodynamic Pads Strip Stabilization
- Increasing the speed of galvanizing lines for reducing their production costs is challenging while main- taining a high coating quality demanded by steel customers. Several issues arising at bath area prevent such speed increase up to or above 200 m/min. Among these issues, corrosion and wear of the immersed hardware, skimming volumes, and wiping conditions are predominant. Regarding the last limitation, the RFCS European project “High Speed Galvanizing” aimed notably at developing a strip stabilization device that could act directly at the wiping level. During that project, CRM Group and its partners have pushed the limit of strip stabilization under TRL-5 conditions at low industrial speed on its Annealing and Hot-Dip Galvanizing Pilot Line. Thanks to a finite element model coupled to an optimization of damping param- eters, both validated by measurements, hydrodynamic pads (WO2017129391), whose effects increase with strip speed, have been tested very close to the wiping level. Consequently, a flat and stable strip could be achieved right between air knives with extremely low residual displacements, even under forced vibra- tions representative of harsh industrial working conditions. The coated product so-obtained was charac- terized with a similar reduction of final coating thickness variations.
- KEYWORDs : Hydrodynamic, Strip, Vibrations, Stabilization, Wiping
- AUTHORs : Olivier Br?gand†, Yves Hardy, Pascal Gerkens, Jean-Claude Golinval, S?bastien Hoffait, Mathieu Bertha, Daniel Simon, Pauline Briault, and Jaap Van Eenennaam
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Page : 86 - 95
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- In-Situ Characterization of the Mechancial Behavior of Hot-Dip Zn-5al Coating: An Overview of Deformation and Damage Mechanisms
- Zinc-based coatings are used in diverse applications mainly for their high resistance to corrosion and other properties such as good longevity. Previous research has focused mainly on microstructure and corrosion resistance of these coatings. However, mechanical properties are seldom mentioned in literature. Only a few studies have investigated mechanical behavior of zinc-based coatings, especially those exhibiting com- plex microstructures after addition of elements. This work focused on a Zn-5Al coating deposited on steel by continuous hot-dip galvanizing, giving a detailed overview of its microstructure and its crystallo- graphic texture. Interesting deformation and damage mechanisms were revealed through in-situ tensile experiments coupled with digital image correlation measurements. Crack distribution and chronology of deformation and damage events were determined and well understood. In this experimental work, diverse techniques ranging from microstructure analysis with SEM and EBSD to the study of the mechanical behavior using micro-mechanical tensile testing, in-situ SEM observations and DIC measurements as well as advanced tech- niques such as focused ion beam for more in-depth studies were considered. The purpose of this work is to give a better understanding of deformation and damage mechanisms of zinc-based coatings.
- KEYWORDs : Hot-dip galvanizing, Microstructure, Mechanical behavior, Deformation, Damage
- AUTHORs : Houssem Eddine Chaieb†, Vincent Maurel, Samuel Forest, Kais Ammar, Franck Nozahic, Joost De Strycker, Jean-Michel Mataigne, Alexandre Tanguy, and Eva H?ripr?
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Page : 96 - 105
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- 해양환경 하에서 침지실험에 의한 나노 고분자 특수도료의 방오 및 방식 성능 평가
- This study conducted immersion tests to evaluate the antifouling and anticorrosion performance of alu- minum alloys coated with antifouling and special paint in a marine environment. Laboratory immersion tests were conducted to evaluate anticorrosion performance, and coastal immersion tests were conducted to evaluate antifouling performance, which was assessed by visual observations. Additionally, the degree of paint deterioration on the specimens was analyzed before and after the laboratory immersion test using a sliding wear experiment. In the coastal immersion test, the antifouling paint showed better antifouling per- formance than the special paint. The special paint was observed to have attached and growing plant and animal marine organisms after 2 weeks of immersion. The laboratory immersion tests showed that the spe- cial paint exhibited superior corrosion resistance compared to antifouling paint. Since the special paint had a smaller friction coefficient and less surface wear damage than the antifouling paint, its durability was confirmed to be relatively excellent.
- KEYWORDs : Paint, Immersion test, Antifouling, Anticorrosion, Marine environment
- AUTHORs : 전우석 · 김유진 · 안홍민 · 박일초†
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