• Corrosion Science and Technology
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• v.21 no.6
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• pp.476-486
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• 2022

Recently, aluminum 6061 instead of copper alloy is used for cooling heat exchangers used in the internal combustion of engines due to its economic feasibility, lightweight, and excellent thermal conductivity. In this study, aluminum 6061 alloy was anodized with oxalic acid, phosphoric acid, or chromic acid as an anodizing electrolyte at the same concentration of 0.3 M. After the third anodization, FDTS, a material with low surface energy, was coated to compare hydrophobic properties and anti-icing characteristics. Aluminum was converted into an anodization film after anodization on the surface, which was confirmed through Energy Dispersive X-ray Spectroscopy (EDS). Pore distance, interpore distance, anodization film thickness, and solid fraction were measured with a Field Emission Scanning Electron Microscope (FESEM). For anti-icing, hydrophobic surfaces were anodized with oxalic acid, phosphoric acid, or chromic acid solution. The sample anodized in oxalic acid had the lowest solid fraction. It had the highest contact angle for water droplets and the lowest contact hysteresis angle. The anti-icing contact angle showed a tendency to decrease for specimens in all solutions.

• Corrosion Science and Technology
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• v.18 no.6
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• pp.258-266
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• 2019

The objective of this study was to evaluate corrosion resistance of additive manufactured 316L stainless steel and alloy 625 powders widely used in corrosion resistance alloys of marine industry in comparison with cast alloys. Directed Energy Deposition (DED) method was used in this work for sample production. DED parameter adjustment was also studied for optimum manufacturing and for minimizing the influence of defects on corrosion property. Additive manufactured alloys showed lower corrosion resistance in seawater compared to cast alloys. The reason for the degradation of anti-corrosion property was speculated to be due to loss of microstructural integrity intrinsic to the additive manufacturing process. Application of heat treatment with various conditions after DED was attempted. The effect of heat treatments was analyzed with a microstructure study. It was found that 316L and alloy 625 produced by the DED process could recover their expected corrosion resistance when heat treated at 1200 ℃.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.1
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• pp.68-74
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• 2014

Recently, concrete facility as advanced water treatment facilities is extending in the water treatment facilities according to raise awareness of pure drinking water and delicious water. For this reason, it is increased to the necessity need to make the standard and the development of waterproofing and anti-corrosion materials for concrete structures applied water treatment tank. So, related research has become active recently. However, as the limit of research focused on durability improvement of top coating material, it is insufficient to study on the adhesion strength between the concrete surface and primer. Therefore, there is to confirm the adhesion of between concrete surface and the three primers used as anti-corrosion waterproofing materials, and to investigate the properties of adhesion strength according to the condition such as dry condition, wet condition, and water pressure condition of the concrete surface in this study.

• Journal of the Korean institute of surface engineering
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• v.52 no.2
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• pp.103-110
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• 2019

As an anti-corrosion method in seawater, cathodic protection is widely recognized as the most effective and technically appropriate corrosion prevention methodology for marine structures against harsh corrosive environment. When applying the cathodic protection in seawater, the surface of the metal facilities the formation of compounds of $CaCO_3$ and $Mg(OH)_2$. These mixed compounds are generally called 'calcareous deposits'. This layer functions as a barrier against the corrosive environment and functions to further inhibit the corrosion process and then leading to a decrease in current demand for cathodic protection. However, calcareous deposit films are partially formed on the surface of the cathode and there are some difficulties to maintain both a corrosion resistance for a long period of time and a strong adhesion between deposits and base metal. In this study, the pulse electrodeposition process was applied to improve adhesion and corrosion resistance of the calcareous deposit films, and to solve the problem of hydrogen embrittlement at high current density. The uniform and compact calcareous deposit films were prepared by pulse electrodeposition process, and their properties were characterized using various surface analytical techniques together with electrochemical methods.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.6
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• pp.95-103
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• 2013

Half Cell Potential (HPC) technique has been widely adopted for its quantitative evaluation of corrosion possibility. In this study, RC specimens with three different cover depths (10mm, 30mm, and 60mm) and w/c ratios (0.35, 0.55, and 0.70) are prepared and accelerated salt spray test (SST) is performed for 45 days. Steel corrosion occurs in the specimens with 0.55 of w/c and 10mm of cover depth. In the case of 0.70 of w/c and 30mm of cover depth, steel corrosion is also monitored. Considering the effect of cover depth and w/c ratio, HCP evaluation equation is proposed and the condition which can control steel corrosion is obtained. Furthermore, anti-corrosive conditions containing w/c ratio and cover depth are analyzed through Life 365 program and the conditions are compared with the results from this study.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.93-93
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• 2013

In recent years, multifunctional ternary nitride thin films have received extenstive attention due to its versatility in many applications. In particular, noble metal based ternary nitride thin films showed a promising properties in the application of Multifunctional heating resistor films because its good electrical properties and excellent resistance against oxidation and corrosion. In this study, we prepared multifunctional noble metal based ternary nitride thin films by atomic layer deposition (ALD) and plasma-enhanced ALD (PEALD) method. ALD and PEALD techniques were used due to their inherent merits such as a precise composition control and large area uniformity, which is very attractive for preparing multicomponent thin films on large area substrate. Here, we will demonstrate the design concept of multifunctional noble metal based ternary thin films. And, the relationship between microstructural evolution and electrical resistivity in noble metal based ternary thin films will be systemically presented. The useful properties of noble metal based ternary thin films including anti-corrosion and anti-oxidation will be discussed in terms of hybrid functionality.

• Journal of Environmental Health Sciences
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• v.36 no.3
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• pp.236-246
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• 2010

In preparative anti-corrosive coating experiments, polyaniline was obtained by reacting an oxidizing agent with the monomer aniline. Further, the primer coating was prepared using a variety of widely-used materials such as urethane resin. For the top coating, epoxy resin and acrylic urethane resin were used. Characteristics of the coatings were assessed according to KS and ASTM specifications, and the structure of the polyaniline was characterized using FT-IR and TGA. For analysis of anti-corrosive properties in salt-spray experiments, measurements of the oxidation state of iron and surface atomic analysis were conducted using XPS and SEM-EDX. Unlike general anti-corrosive coatings which exhibit anti-corrosive effects only as a primer coating, the anti-corrosive coatings using polyaniline as the anti-corrosive pigment showed a marked synergistic effect with the top coatings. In other words, the top coatings not only produce a fine view effect, but also increase, through interaction with the primer coatings, the resistance to diffusion of corrosive factors from the external environment. It was also found that, unlike the heavy metal oxide-forming layer of the passive barrier alone, the polyaniline anti-corrosive pigment oxidized iron at the interface with the iron substrate to form a passive barrier in the oxidic layer, and itself formed a potential barrier layer with anti-corrosive factors from the external environment. Although the passive layer was damaged, the damaged area did not become completely oxidized iron; on the contrary, it showed a tendency to reduction. This can be interpreted such that a passive layer is formed again on the damaged area, and that at the same time there is a tendency to self-healing.

• Nuclear Engineering and Technology
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• v.53 no.11
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• pp.3474-3490
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• 2021

Sodium-cooled fast reactor (SFR) is the preferred technology of the generation-IV fast neutron reactor, and its core body mainly uses nuclear-grade 316 stainless steel. In order to prolong the design life of SFRs to 60 years and more, it is necessary to summarize and analyze the anti-corrosion effect of nuclear grade 316 stainless steel in high temperature sodium environment. The research on sodium corrosion of nuclear grade 316 stainless steel is mainly composed of several important factors, including the microstructure of stainless steel (ferrite layer, degradation layer, etc.), the trace chemical elements of stainless steel (Cr, Ni and Mo, etc) and liquid impurity elements in sodium (O, C and N, etc), carburization and mechanical properties of stainless steel, etc. Through summarizing and constructing the sodium corrosion rate equations of nuclear grade 316 stainless steel, the stainless steel loss of thickness can be predicted. By analyzing the effects of temperature, oxygen content in sodium and velocity of sodium on corrosion rate, the basis for establishing integrity evaluation standard of SFR core components with sodium corrosion is provided.

• Journal of the Korean institute of surface engineering
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• v.53 no.5
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• pp.201-206
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• 2020

A SiOxCy(-H) thin film was synthesized by atmospheric pressure dielectric barrier discharge(APDBD), and a SiO₂-like layer was formed on the surface of the film by oxidation treatment using oxygen plasma. Hexamethylcyclotrisiloxane was used as a precursor for the SiOxCy(-H) synthesis, and He gas was used for stabilizing APDBD. Oxygen permeability was evaluated by forming an oxidized SiOxCy(-H) thin film on a PET film. When the single-layer oxidized SiOxCy(-H) film was coated on the PET, the oxygen gas permeability decreased by 46% compared with bare PET. In case of three-layer oxidized SiOxCy(-H) film, the oxygen gas permeability decreased by 73%. The oxygen permeability was affected by the thickness of the SiO₂-like layer formed by oxidation treatment rather than the thickness of the SiOxCy(-H) film. The excellent corrosion resistance was demonstrated by coating an oxidized SiOxCy(-H) thin film on the silver-coated aluminum PCB for light emitting diode (LED).

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.505-510
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• 2002

The Friction Stir Welding (FSW) is a new joining method that was developed at The Welding Institute (TWI) in England in 1991. It applied heating by the rotational friction and material plastic flow. It was developed as a new joining method to solve the problems of epochally in the welding of Al alloys. In the study, 6000series of Alloy composed of AI-Mg-Si, one of the Al alloys that are utilized for shipbuilding and construction, is selected as a specimen and the numerical is executed against the welded zone of FSW. The material used in this study had the unique properties of strength and anti-corrosion, but since the welded joint of this material is easily softened by the welding heat, FSW is executed and the numerical analysis is carried out around the joint. To examine the mechanical behaviors and properties, F.E.M analysis is executed and the developed thermal-elastic-plastic [mite analysis are used.