• Corrosion Science and Technology
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• v.14 no.5
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• pp.218-225
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• 2015

The electrochemical behaviors of various metals with and without diamond-like-carbon (DLC) coating in 3.5 wt% NaCl solution were investigated. The effect of hydrodynamic conditions was focused by employing a rotating disc electrode (RDE). The experimental results showed that each bare metal had a more positive corrosion potential and a higher corrosion rate due to enhanced oxygen transport at the higher rotating speed of the RDE. DLC coating caused a substantial increase in the corrosion resistance of all metals studied. However, localized corrosion was still found in the DLC-coated metal at sites where deposition defects existed. Surface morphology examination was performed after the electrochemical test to confirm the roles of hydrodynamic conditions and DLC coating.

• Corrosion Science and Technology
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• v.8 no.3
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• pp.103-109
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• 2009

An epoxy coating was designed to give a hydrophobic property on its surface by modifying it with three types of Amino Terminated Polydimethylsiloxane (ATP), and then effects of the modification on the structure, surface hydrophobic tendency, water transport behavior and hence corrosion protectiveness of the modified epoxy coating were examined using FT-IR spectroscopy, hydrothermal cyclic test, and impedance test. The surface of epoxy coating was changed from hydrophilic to hydrophobic property due primarily to a phase separation tendency between epoxy and modifier by the modification. The phase separation tendency is more appreciable when modified by ATP with higher molecular weight ATP at higher content. Water transport behavior of the modified epoxy coating decreased more in that with higher hydrophobic surface property. The resistance to localized corrosion of the modified epoxy coated carbon steel was well agreed with its water transport behavior and hydrophobic tendency.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2008.11a
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• pp.68-68
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• 2008

There are several methods for oxide coating on metals, such as aluminum or carbon nanotubes(CNTs). Usually CVD method is introduced for various oxide coating on CNTs. Another method is electrochemical method which use potential-pH diagram for oxide coating on metal or CNTs. In this experiment, electrochemical coating parameter for oxide coating on aluminum template modified by acids and hydrogen peroxide ($H_2O_2$) were examined. SEM micrographs displayed clearly $Ni(OH)_2$ coating on template. For confirmation of electrochemical method application to EDLC electrode material fabrication, EDS spectrum was analyzed.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1737-1739
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• 2004

Diamond-like carbon (DLC) films were prepared with RF-PECVD (Plasma Enhanced Chemical Vapor Deposition) method on coming glass and silicon substrates using methane ($CH_4$) and hydrogen ($H_2$) gases. We examined the effects of $CH_4$ to $H_2$ ratios on tribological and optical properties of the DLC films. The structure and surface morphology of the films were examined using Raman spectroscopy and atomic force microscopy (AFM). The hardness of the DLC film was measured with nano-indentor. The optical properties of DLC thin film were investigated by UV/VIS spectrometer and ellipsometry. And also, solar cells were fabricated using DLC as antireflection coating before and after coating DLC on silicon substrate and compared the efficiency.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.23 no.4
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• pp.392-397
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• 2014

Recently, there is an increase in the need for precision linear stages with vacuum compatibility in such areas as lithography equipment for wafer or mask manufacturing, mask mastering equipment for optical data storage and electron beam equipment. A simple design, high stiffness and low cost can be achieved by using ball bearings. However, a ball bearing have friction and wear problems just as in ambient air. In order to decrease the friction, a special finish, a diamond-like carbon (DLC) film coating, is applied to the surface of a guide rail by sputtering deposition. This paper presents the result of an experimental investigation on the control performance of a ball bearing-guided linear motion stage under two environmental conditions: in air and vacuum. A comparison between the results with and without the DLC coating was also considered in the experimental investigation.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.167.1-167.1
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• 2014

We report a facile method to fabricate superhydrophobic, transparent and conductive film using multi-walled carbon nanotubes (MWCNTs) which are coated by polydimethylsiloxane (PDMS). In order to prepare a film, PDMS coated MWCNTs were dispersed in solvents and the solution was drop-casted on substrates. It was demonstrated that the PDMS coating enhanced the dispersion of MWCNTs in diverse solvents such as dimethyl formamide(DMF) and acetone without the use of acids or surfactants, which are the common methods. In the case of DMF solvent, dispersion of MWCNT was improved by 40 % upon PDMS-coating of MWCNT. Enhanced dispersion of MWCNTs made it possible to fabricate transparent and conductive film homogeneously on the substrate and PDMS-coating on MWCNTs also made the surface hydrophobic. We can fabricate a uniform and multifunctional MWCNT film (transparent, conductive, superhydrophobic and flexible) which is applicable on large area without any physical damage and expensive equipment.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.135-135
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• 2016

Recently flexible electrode materials have attracted attention in various electrical devices. In general, copper(Cu) is widely used electrical conductive material. However, Cu film showed drastically reduction of electrical conductivities under an applied tensile strain of 10%. These poor mechanical characteristics of Cu have difficulty applying in flexible electronic applications. In this study, mechanical flexibilities of Cu thin film were improved by hybridization with carbon nanotubes(CNTs) and laser sintering. First, thin carbon nanotube films were fabricated on a flexible polyethylene terephthalate(PET) substrate by using ultrasonic spray coating of CNT dispersed solution. After then, physically connected CNT-Cu NPs films were formed by utilizing ultrasonic spray coating of Cu nanoparticles dispersed solution on prepared CNT thin films. Finally, CNT-Cu thin films were firmly connected by laser sintering. Therefore, electrical stabilities under mechanical stress of CNT-Cu hybrid thin films were compared with Cu thin films fabricated under same conditions to confirm improvement of mechanical flexibilities by hybridization of CNT and Cu NPs.

• Steel and Composite Structures
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• v.17 no.2
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• pp.173-184
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• 2014

This study aimed to theoretical calculate the thermal residual stress in continuous SiC fiber reinforced titanium matrix composites. The analytical solution of residual stress field distribution was obtained by using coaxial cylinder model, and the numerical solution was obtained by using finite element model (FEM). Both of the above models were compared and the thermal residual stress was analyzed in the axial, hoop, radial direction. The results indicated that both the two models were feasible to theoretical calculate the thermal residual stress in continuous SiC fiber reinforced titanium matrix composites, because the deviations between the theoretical calculation results and the test results were less than 8%. In the titanium matrix composites, along with the increment of the SiC fiber volume fraction, the longitudinal property was improved, while the equivalent residual stress was not significantly changed, keeping the intensity around 600 MPa. There was a pronounced reduction of the radial residual stress in the titanium matrix composites when there was carbon coating on the surface of the SiC fiber, because carbon coating could effectively reduce the coefficient of thermal expansion mismatch between the fiber and the titanium matrix, meanwhile, the consumption of carbon coating could protect SiC fibers effectively, so as to ensure the high-performance of the composites. The support of design and optimization of composites was provided though theoretical calculation and analysis of residual stress.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.6
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• pp.656-662
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• 2015

In the present study, multi-layered Si DLC (Silicon Diamond-Like Carbon) coatings with HMDSO (Hexamethyldisiloxane) buffer layers are applied on SKD 11 substrates by PECVD (Plasma Enhanced Chemical Vapor Deposition) with different HMDSO gas flow rates, while the gas flow rate of $C_2H_2$ is fixed to enhance the electric resistivity of forming dies for electrically assisted forming. The HMDSO buffer layer is introduced to increase adhesion between the base metal and Si-DLC layers. The result of evaluation of electric resistivity and adhesion strength shows that the properties are affected by the flow rate of HMDSO, while the flow rate of 80 sccm results in the coating with the highest electric resistivity and adhesion strength among the selected flow rates.

• Composites Research
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• v.21 no.1
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• pp.8-15
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• 2008

Single-walled carbon nanotube networks(SWNT-networks) were uniformly formed on a glass substrate by the dip-coating method. The changes of electrical and optical properties of SWNT-networks were investigated with respect to processing variables including number of dip, concentration of SWNT-colloidal solution, withdrawal velocity. Consequently, the sheet resistance and transmittance of the SWNTs-networks were sensitively controlled by the processing variables. The networks have highly uniform sheet resistance and optically excellent transmittance within the range of visible ray.