• Advances in nano research
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• v.10 no.3
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• pp.211-219
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• 2021

The evaluation of the corrosion resistance of titanium with a TiO2 nanotubes top layer was carried out (TiO2 NT). These nanostructures were evolved into anatase nanoparticles without heat treatment in an aqueous medium, which is a novel phenomenon. This work analyzes the layer between the nanotube bottom and the substrate, which is thin and still susceptible to corrosion. The bottom of TiO2 nanotubes having Fluor resulting from the synthesis process changed between amorphous to crystalline anatase with a crystallite size of about 4 nm, which influenced the corrosion rates. Four kinds of samples were evaluated. A) NT by Ti anodizing; B) NTSB for Ti plates, either modifying its surface or anodizing the modified surface; C) NT-480 for anodized Ti and heat-treated (480℃) for reaching the anatase phase; D) NTSB-480 for Ti plates, first, modifying its surface using sandblast, after that, anodizing the modified surface, and finally, heat-treated to 480℃ to compare with samples having induced crystallization and passivation. Four electrochemical techniques were used to evaluate the corrosion rates. The surfaces having TiO2 nanotubes with a sandblast pre-treatment had the highest resistance to corrosion.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2003.11a
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• pp.227-232
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• 2003

Anodizing film was prepared by anodic oxidation of pure aluminum(purity > 99.50) using DC power supply for constant current mode in an electrolytic solution of surface of sulfuric acid. Effects of pre-treatment process such as chemical polishing, acid cleaning, alkali etching before anodic oxidation, were studied to microstructures and surface morphologies. A roughness on surface of anodizing film had to be decreased for amorphous phase by anodic oxidation. A roughness on surface of anodizing film decrease as annealing temperature increased in chemical polishing.

• Journal of the Korean institute of surface engineering
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• v.57 no.3
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• pp.201-207
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• 2024

This study compared the chemical resistance properties according to various sealing treatment methods for the anode film formed during the anodization process of Al6061 alloy. Al6061 aluminum was used in four different sealing treatment methods: boiling water sealing, lithium sealing, nickel sealing, and pressurized sealing, and each sample was evaluated for corrosion resistance through a 5% HCl bubble test and the microstructure was observed through a scanning electron microscope(SEM). According to the results, corrosion resistance increased as time and temperature increased in all sealing treatment methods. Relatively, corrosion resistance was high in the order of boiling water sealing, lithium sealing, nickel sealing, and pressure sealing, and the best corrosion resistance was found in pressure sealing. These research results can be helpful in selecting a process necessary to improve the efficiency and performance of anodizing process in the industrial field using aluminum alloys.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.96.1-96.1
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• 2017

This presentation introduces anodizing science of typical valve metals of Al, Mg and Ti, based on the ionic transport through the andic oxide films in various electrolyte compositions. Depending on the electrolyte composition, metal ions and anions can migrate through the andic oxide film without its dielectric breakdown when point defects are present within the anodic oxide films under high applied electric field. On the other hand, if anodic oxide films are broken by local joule heating due to ionic migration, metal ions and anions can migrate through the broken sites and meet together to form new anodic films, known as plasma electrolytic oxidation (PEO) treatment. In this presentation, basics of conventional anodizing and PEO methods are introduced in detail, based on the ionic migration and movement mechanism through anodic oxide films by point defects and by local dielectric breakdown of anodic oxide films.

• Journal of the Korean institute of surface engineering
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• v.13 no.4
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• pp.221-227
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• 1980

When anodizing the Al in the acid electrolyte, it is well known that the parallel pores grow continuously perpendicular to the surface. This fact can be used for the manufacturing of the porous membrane, if thc pores pass through the anodized foil. Anodizing both surfaces of the Al-foil spontaneously in 20$^{\circ}C$, 2% oxalic acid under tile potentiostatic condition, it is found that the harrier layer remaining in the midst of the foil finally disappears and thc pores pass through the foil. And examined the porous structure change when the voltage is changed during the anodizing treatment. From the result, it is revealed that the new pores and cell grow, adjusting themselves to the final voltage. The characteristic of the porous membrane is greatly dependent upon the diameter of the pore and the cell. So studied the relationship between the voltage and the diameter of the pore and the cell quantitatively with the aid of field-assisted dissolution concept. And derived the following two equation, Pi = 8.32Vi, Ci = 26.80Vi. These equations are in good accord with the experimental data above 30V, but do not accord nuder 30V.

• Korean Journal of Materials Research
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• v.23 no.1
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• pp.72-80
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• 2013

Recently, consumption of magnesium alloys has increased especially in the 3C (computer, communication, camera) and automobile industries. The structural application of magnesium alloys has many advantages due to their low densities, high specific strength, excellent damping and anti-eletromagnetic properties, and easy recycling. However, practical application of these alloys has been limited to narrow uses of mild condition, because they are inferior in corrosion resistance and wear resistance due to their high chemical reactivity and low hardness. Various wet and dry processes are being used or are under development to enhance alloy surface properties. Various conversion coating and anodizing methods have been developed in a view of eco-friendly concept. The conventional technologies, such as diffusion coating, sol-gel coating, hydrothermal treatment, and organic coating, are expected to be newly applicable to magnesium alloys. Surface treatments for metallic luster or coloring are suggested using the control of the micro roughness. This report reviews the recent R&D trends and achievements in surface treatment technologies for magnesium alloys.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.2
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• pp.72-77
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• 2016

Airplane reservoirs made of Al7075 are coated with an anodizing layer to maintain precision, air tightness and corrosion resistance. It is commonly required that the inner surface roughness of the reservoir be less than an average $0.2{\mu}m$ to maintain stable oil pressure. Even though precision polishing is necessary to achieve this quality it is not easy. Inner surface roughness is not uniform and the quality of the product is irregular because most of the work is done by hand. The purpose of this study is to design an exclusive polishing machine and to determine the standard cutting condition and polishing condition necessary for good inner surface roughness and to improve workefficiency.

• Tribology and Lubricants
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• v.26 no.1
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• pp.68-72
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• 2010

A ceramic coating is a surface treatment method that is being used widely in the industrial field, recently. Ni-P plating is also being used widely because of its corrosion resistance and low cost. An anodizing method is applicable to aluminum alloy. An anodizing method generates a thick oxide layer on the surface and then, that heightens hardness and protects the surface. These surface treatments are applied to various mechanical components and treated surfaces relatively move one another. In this study, tribological characteristics of Ni-P plating and TiAlN coating on anodized Al alloy are compared. The counterpart, anodized Al alloy, is worn out abrasively by Ni-P plating and TiAlN coating that have higher hardness. Abrasively worn debris accumulated on the surfaces of Ni-P plating and TiAlN coating, and then transferred layer is formed. This transferred layer affects the amplitude of variation of friction coefficient, which is related to noise and vibration. The amplitude of variation of friction coefficient of Ni-P plating is lower than those of TiAlN coating during the tests.

• Journal of the Korean institute of surface engineering
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• v.49 no.6
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• pp.549-554
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• 2016

Low melting metals are difficult to weld because it is vaporized. But epoxy resin make bonding possible using low melting material and dismissal materials. This study is to improve the bonding strength of epoxy and substrate by mechanical and electrochemical methods. In case of mechanical work, bonding strength is 17.6MPa and in case of pre-work, bonding strength is 15.3MPa. When anodizing and mechanical work is applied, bonding strength is 25.3Mpa is increased 165%. When anodizing is applied, bonding strength is 27.6Mpa.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.545-546
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• 2006

This study was performed to investigate the surface properties of electrochemically oxidized pure titanium by anodic spark discharging method. Commercially pure titanium plates of $10{\times}20{\times}1[mm]$ in dimensions were polished sequentially emery paper. Anodizing was performed at current density of $76.2\;[mA/cm^2]$, application voltage of 290, 350, 400 [V] using a regulated DC power supply, which allowed automatic transition constant current when a preset maximum voltage has been reached. The Ti surface oxided films was characterized by scanning electron microscope(SEM). The precipitation of HA(Hydroxyapatite) crystals on anodized surface was greatly accelerated by hydrothermal treatment. The concentrations of DL-$\alpha$-Glycerolphosphate Magnesiurn(DL-$\alpha$-GP-Mg) salt and Ca acetate in an electrolyte was highly affected the precipitation of HA crystals converted by Ti Anodized oxide films by Shape of Impulse Voltage.