• Journal of Electrochemical Science and Technology
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• 제10권2호
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• pp.223-230
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• 2019

A facile method for surface coating with $Li_2TiF_6$ which has a high lithium-ion conductivity, on $LiMn_2O_4$ spinel cathode material for high performance lithium ion batteries. The surface coating is performed by using a co-precipitation method with $Li_2CO_3$ powder and $H_2TiF_6$ solution under room temperature and atmospheric pressure without special equipment. Total coating amount of $Li_2TiF_6$ is carefully controlled from 0 to 10 wt.% based on the active material of $LiMn_2O_4$. They are evaluated by a systematic combination of analyses comprising with XRD, SEM, TEM and ICP. It is found that the surface modification of $Li_2TiF_6$ is very beneficial to high cycle life and excellent rate capability by reducing surface failure and supporting lithium ions transportation on the surface. The best coating condition is found to have a high cycle life of $103mAh\;g^{-1}$ at the 100th cycle and a rate capability of $102.9mAh\;g^{-1}$ under 20 C. The detail electrochemical behaviors are investigated by AC impedance and galvanostatic charge and discharge test.

• 대한금속재료학회지
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• 제48권1호
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• pp.49-56
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• 2010

This study investigated how the surface of Al-12wt.%Si alloy modified by the plasma electrolytic oxidation process (PEO). The PEO process was performed in an electrolyte with sodium hexametaphsphate as a conducting salt, and the effect of ammonium metavanadate on variations in the morphology of electrochemically generated oxide layers on the alloy surface was investigated. It is difficult to form a uniform passive oxide layer on Al alloys with a high Si content due to the differences in the oxidation behavior of the silicon-rich phase and the aluminum-rich phase. The oxide layer covered the entire surface of the Al-12WT.%Si alloy uniformly when ammonium metavanadate was added to the electrolyte. The oxide layer was confirmed as a mixture of $V_2O_3$ and $V_2O_5$ by XPS analysis. In addition, the oxide layer obtained by the PEO process with ammonium metavanadate exhibited a black color. Application of this surface modification method is expected to solve the problem of the lack of uniformity in the coloring of oxide layeres caused by different oxidation behaviors during a surface treatment.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.401-401
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• 2016

Although vertically aligned one-dimensional (1D) structure has been considered as efficient forms for photoelectrode, development of efficient 1D nanostructured photocathode are still required. In this sense, we recently demonstrated a simple fabrication route for CuInS2 (CIS) nanorod arrays from aqueous solution by template-assisted growth-and-transfer method and their feasibility as a photoelectrode for water splitting. In this study, we further evaluated the photoelectrochemical properties surface-modified CIS nanorod arrays. Surface modification with CdS and ZnS was performed by successive ion layer adsorption and reaction (SILAR) method, which is well known as suitable technique for conformal coating throughout nanoporous structure. With surface modification of CdS and ZnS, both photoelectrochemical performance and stability of CuInS2 nanorod arrays were improved by shifting of the flat-band potential, which was analyzed both onset potential and Mott-schottky plot.

• Tribology and Lubricants
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• 제16권1호
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• pp.15-21
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• 2000

Radiation of Nd-YAG laser changes and refines the surface microstructure of steels, which gives rise to enhancement of hardness and resulting wear resistance. In the present work, the effect of processing parameters during the surface modification with laser on the wear behavior of the SM45C steel was studied by means of wear testing. The counter material was alumina ceramics. The microstructure observation revealed the dependence of molten depth and width on the defocusing distance. The laser modification of steel surface give rise to improved wear resistance in the testing speed range of either <0.2 m/s or >0.9 m/s Material transfer from steel was wear observated the surface of counter material when testing speed was lower than 0.7 m/s.

• 한국잠사곤충학회지
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• 제39권1호
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• pp.56-61
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• 1997

The silk fibroin solution was prepared and applied to the surface of fabrics for the purpose of weighting as well as a surface modification. The water-soluble fibroin solution can be obtained by dissolving the cocoon fibroin in a boiling solution of 50% calcium chloride for 60 minutes. For the fixation of a water soluble fibroin onto the fabric surface, the various methods were investigated. The fixation can be achieved on a silk fabric by the after treatment with ethanol, stannous choride and methacrylamide. On the other hand, the epichlorhydrin compound is the most promising fixation agent for a cotton fabric. As a result of the examination of property changes, the softness and crease recovery were lessened for a silk crepe fabric by treating with 1-2% fibroin solution, while those properties were improved for a silk knit fabric.

• Elastomers and Composites
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• 제50권1호
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• pp.62-67
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• 2015

The surface modification of microfibriled cellulose (MFC) was carried out through the hydrolysis-condensation reaction using (3-aminopropyl)triethoxysilane (APS) and 3-glycidyloxypropyltriethoxysilane (GPS) and then the modified cellulose was compounded with bio-degradable poly(lactic acid) (PLA). Also, pristine MFC was compounded with PLA as a control groups. The confirmation of surface modification for the pristine MFC was characterized by FT-IR and SEM/EDX. The thermal and mechanical properties of the PLA/MFC composites depended on the content of MFC and the type of silane coupling agents. From the thermal, morphological and mechanical behaviors of the PLA/MFC composites, it was found that GPS-MFC was more successful to improve the interface adhesion between PLA matrix and the surface of MFC than that of APS-MFC.

• 한국전기전자재료학회논문지
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• 제19권3호
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• pp.233-239
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• 2006

Two different nanofluids were prepared by dispersing $Al_{2}O_3$ nanoparticles in transformer oil after hydrophobic surface modification. The agglomerated alumina nanoparticles with diameters from ${\mu}m$ to mm were ball-milled and then treated with surfactants such as lauric acid, stearic acid and oleic acid. The surface characteristics of modified nanoparticles were examined by FTIR spectroscopy. It showed that the hydrophobicity of nanoparticles was caused by esterification between hydroxyl groups on the particle surface and functional groups of surfactant. The shape and size distribution of ball-milled particles were analyzed by TEM and PSA. The results compared with the primary particles indicated that the size distributions of nanoparticles were dependant on milling times. The dispersion stability of modified nanoparticles dispersed in oil was highly dependent on the composition and amounts of surfactants.

• International Journal of Precision Engineering and Manufacturing
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• 제9권4호
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• pp.71-73
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• 2008

The development of polymer/inorganic nanocomposites has attracted a great deal of interest due to the improved hybrid properties derived from the two different components. Various nanoscale fillers have been used to enhance polymer mechanical and thermal properties, such as toughness, stiffness, and heat resistance. The effects of the filler on the final properties of the nanocomposites are highly dependent on the filler shape, particle size, aggregate size, surface characteristics, polymer/inorganic interactions, and degree of dispersion. In this paper, we describe the influence of different $CaCO_3$ dispersion methods on the thermal properties of polyethylene terephthalate (PET)/$CaCO_3$ composites: i.e., the adsorption of $CaCO_3$ on the modified PET surface, and the hydrophobic modification of the hydrophilic $CaCO_3$ surface. We prepared PET/$CaCO_3$ nanocomposites using a twin-screw extruder, and investigated their thermal properties and morphology.

• 멤브레인
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• 제30권4호
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• pp.205-212
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• 2020

This short review focuses on fouling by proteins and macromolecules in microfiltration/ultrafiltration. First, an experimental system that enables investigation of how the extent of the adsorption of proteins and macromolecules on membrane surfaces contributes to a decrease in filtrate flux in microfiltration/ultrafiltration is described. Using this system, a causal relationship - not a correlation - indicating that adsorption results in a decrease in filtrate flux could be clearly demonstrated in some cases. Second, a hydration structure at the membrane surface that can suppress adsorption is discussed, inspired by biomaterial research. In their hydrated states, polymers with low-fouling properties have water molecules with a particular structure. Finally, some successful examples of the development of low-fouling membranes via surface modification using low-fouling polymers are discussed.

• 한국전기전자재료학회논문지
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• 제11권4호
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• pp.293-297
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• 1998

The influence of ion implantation on surface properties of polymers was studied. We investigated microhardness, friction, wear and wettablility of polyimide. Energies of 50, 200keV were used with doses range from $1{\times}10^{13} to 1{\times}10^{16} [ions/cm^2]$. The implanted ion species were B, N and Ar. The microhardness of polyimide was increased after implantation for doses of $1{\times}10^{15}\; [ions/cm^2]$. A reduction of the friction coefficient was in most case correlated with a reduction of wear. The contact angles of water for $B^+,N^+$ implanted polyimide decreased from $76^{\circ}C$ to zero, as the fluencies increased at energies of 50 and 200 KeV. However, the contact angle of Ar ion implanted polyimide did not change under ambient room conditions even if the time elapsed. SEM measurement was performed to characterize the modified surface layer.