• Polymer(Korea)
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• v.38 no.1
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• pp.1-8
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• 2014

The effects of surface color and morphology on the mar behaviors of urethane-acrylate coated surfaces were examined. The superiority of mar resistance was observed in the order of white, red and black-colored samples. This can be explained by a contrast effect. In other words, in case of black colored sample, it takes place the defuse reflection of the incident light on the damaged region where mar damage exerts, leading to whitening phenomenon. Therefore, the damaged region is easily recognized by contrasting the black background. On the other hand, it is difficult for the white-colored sample to perceive the mar-damaged area by the white background acting as protecting coloration. As the gloss of urethane-acrylate coated surface increases, it is observed that there is an increase in the number of carbonyl (-C=O) function group, amount of ethylene and silica. The enhancements of surface rigidity by adding the silica particles and formation of carbonyl function groups by the surface oxidation lead to the increase in mar resistance, while the increase of polyethylene wax is responsible for the improved gloss and smooth-faced surface. Based on the above findings, technical approaches leading the improvement of mar resistance of the urethane-acrylate coated surface are discussed.

• Tribology and Lubricants
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• v.38 no.4
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• pp.136-142
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• 2022

This paper investigates the enhanced wear performance of a CrAl coated accident tolerant fuel (ATF) cladding. In the wake of the Fukushima accident, extensive research on ATF with respect to improving the oxidation resistance of cladding materials is ongoing. Since coated Zr claddings can be applied without major changes to the criteria for reactor core design, many researchers are studying coatings for claddings. To improve the quality of the CrAl coating layer, optimization of the manufacturing process is imperative. This study employs arc ion plating to obtain improved CrAl coated claddings using CrAl binary alloy targets through an improved coating method. Surface roughness and adhesion are improved, and droplets are reduced. Furthermore, the coated layer has a dense and fine microstructure. In scratch tests, all the tested CrAl coated claddings exhibit a superior resistance compared to the Zr cladding. In a fretting wear test, the wear volume of the CrAl coated claddings is smaller compared to the Zr cladding. Furthermore, the coated cladding manufactured through the improved process exhibits better wear resistance than other CrAl coated claddings. Based on these results, we suggest that fine microstructure is attributed to a mechanically and microstructurally robust CrAl coating layer, which enhances wear resistance.

• Composites Research
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• v.33 no.5
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• pp.235-240
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• 2020

In this study, in order to improve the impact resistance of the B₄C tile-inserted B₄C_p/Al7075 hybrid composite, a control method of the B₄C/Al7075 interface was developed and the characteristics of the controlled interface were analyzed. B₂O₃, Ni, and Si were coated on the B₄C tile surface using additional thermal oxidation, electroless plating, and plasma spraying. The coated B₄C tile is inserted into the B₄C_p/Al7075 composite material using the liquid pressurization method. Interfacial energy, bonding strength, and impact resistance were measured to analyze the effect of the coating. All coatings enhanced interfacial energy, bonding strength, and impact resistance, and in particular, it was confirmed that the impact resistance increased by 86.8% when B₂O₃ coating was used. This study is significant in developing and analyzing a core surface treatment method that improves the performance of B₄C/Al series composites, which are attracting attention as next-generation lightweight amour and bulletproof materials.

• Korean Journal of Materials Research
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• v.21 no.1
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• pp.8-14
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• 2011

To improve the chemical stability of metal, the ceramic coatings on metallic materials have attracted interest from many researchers due to the chemical inertness of ceramic materials. To endure strong acids, SiOC coating on metal substrate was carried out by dip coating method using 20wt% polyphenylcarbosilane solution; SiC powder was added to the solution at 10wt% and 15wt% to improve the mechanical properties and to prevent cracks of the film. Thermal oxidation as a curing step was carried out at $200^{\circ}C$ for crosslinking of the polyphenylcarbosilane, and the coating samples were pyrolysized at $800^{\circ}C$ under argon to convert the polyphenylcarbosilane to SiOC film. The thicknesses of the SiOC coating films were $2.36{\mu}m$ and $3.16{\mu}m$. The quantities of each element were measured as $SiO_{1.07}C_{6.33}$ by EPMA, and it can be confirmed that the SiOC film from polyphenylcarbosilane was formed in a manner that was carbon rich. The hardness of the SiOC film was found to be 3.2Gpa through nanoindentor measurement. No defect including cracks appeared in the SiOC film. The weight loss of the SiOC coated stainless steel was within 2% after soaking in 10% HCl solution at $80^{\circ}C$ for one week. From these results, SiOC coating shows good potential for application to protect against severe chemical corrosion of stainless steel.

• Applied Chemistry for Engineering
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• v.2 no.2
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• pp.175-184
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• 1991

Ultraviolet curable coatings are often used to protect the surface of polymer materials exposed to the ultraviolet radiation. However, the adhesion of epoxy acrylate on poly(vinyl chloride) and the UV curable coating on polystyren are poor. The objective of this work was to improve the adhesion of coating according to various formulations of the reactive diluents and finishing methods using the photografting of multifunctional acrylate and the surface activation on polymer surface impregnated a phtoinitiator. The addition of Tripropylene glycole diacrlate in the formulation of coating results in the improvement of adhesion of coating due to the flexibility. But the increase of the crosslinking density which results from the oxidation of surface during the exposure of UV radiation caused the loss of adhesion of coating exept the photografting method. In the trimethylolpropane triacrylate the improvement of adhesion are considerable due to the chemical bond between multifundtional acrylate and surface. From this work we expect to achieve the varity and functionality in the formulation of coating according to the photografting and surface activating of polymer.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.3
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• pp.316-322
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• 2006

The current study evaluated the technical feasibility of the application of $TiO_2$ photocatalysis for the removal of nocotine which has well known as a representative material of environmental tobacco smoke(ETS). Four different preliminary experiments were performed for the evaluation of nicotine removal using photocatalyst-coated construction materials. The photocatalytic removal of nicotine was investigated for five parameters: dry condition of coating tiles, type of coating sol, number of coatings, relative humidity(RH), and input concentrations. Prior to performing the parameter tests, adsorption of nicotine onto the current experimental system was surveyed. All the variables tested in the present study exhibited to influence the photocatalytic decomposition of Nicotine. A dry condition of high temperature and short dry period presented higher photocatalytic oxidation(PCO) efficiency compared to that of low temperature and long dry period. ST-KO3 sol showed higher decomposition efficiency than E-T Sol. The PCO efficiency increased as the number of coating increased. High humidity and low input concentrations exhibited higher PCO efficiency. Consequently, it is noted that the five parameters tested in the present study should be considered for the application of photocatalyst-coated construction materials in cleaning nicotine in ETS.

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.4
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• pp.376-384
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• 2009

Purpose: The purpose of this study was to evaluate the response of osteoblast-like cells to Ca-P coated surface obtained via Ion beam-assisted deposition (IBAD) method and Sol-Gel process on anodized surface by cellular proliferation and differentiation. Material and methods: The surface of a commercially pure titanium (Grade IV) discs with dimension of 10mm diameter and 2 mm thickness was modified by anodic oxidation under a constant voltage of 300 V. The experimental groups were coated with Ca-P by the IBAD method and Sol-Gel process on anodized surface. The surface roughness (Ra) of specimens was measured by optical interferometer and each surface was examined by SEM. To evaluate cell response, MG63 cells were cultured and cell proliferation, ALP activity and the ability of cell differentiation were examined. Also, cell morphology was examined by SEM. The significant of each group was verified by Kruskal-Wallis Test ($\alpha$=.05). Results: The Ra value of Ca-P coated surface by IBAD method was significantly higher than Ca-P coated surface by Sol-gel process (P < .05). The level of cell proliferation and ALP activity was higher in Ca-P coated surface by IBAD method (P<.05). The expression of ALP showed higher level expression in Ca-P coated surface by IBAD method. Cells grown on Ca-P coated surface by IBAD method were uniformly distributed and developed a very close layer. Conclusion: These experiments showed better performances of Ca-P coated surface by IBAD method with respect to Ca-P coated surface by Sol-gel process. Ca-P coated surface by IBAD method appear to give rise more mature osteoblast characteristics and might result in increased bone growth and bone-implant contact.