• Journal of Mechanical Science and Technology
• /
• v.15 no.7
• /
• pp.859-865
• /
• 2001

This paper reports on the theoretical analysis of mixed lubrication for the piston ring. The analytical model is presented by using the average flow and asperity contact model. The cyclic variations of the nominal minimum oil film thickness are obtained by numerical iterative method. The total friction is calculated by using the hydrodynamic and asperity contact theory. The effect of the roughness height, pattern, and engine speed on the nominal minimum film thickness, friction force, ad frictional power losses are investigated. As the roughness height increases, the nominal oil film thickness and total friction force increase. Also, the effect of the surface roughness on the boundary friction is dominant at low engine speed and high asperity height. The longitudinal roughness pattern shows lower mean oil film pressure and thinner oil film thickness compared to the case of the isotropic and transverse roughness patterns.

• Journal of the Semiconductor & Display Technology
• /
• v.19 no.1
• /
• pp.93-96
• /
• 2020

Polyimide thin film was prepared by annealing the polyamic acid that was synthesized through co-deposition of diamine and dianhydride. The polyamic acid and polyimide thin film were characterized with FT-IR and HR FE-SEM. The average roughness of the film surface, evaluated with AFM, were 0.385 nm and 0.299 nm after co-deposition, and annealing at 120 ℃ respectively. OLED was passivated with the polyimide layer of 200 nm thickness. While the inorganic passivation layer enhances the WVTR of OLED, the organic passivation layer gives flexibility to the OLED. The in-situ passivation of OLED with organic thin film layer provides the leading technique to develop flexible OLED Display.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2007.04a
• /
• pp.73-73
• /
• 2007

Amorphous BON and Si-DLC thin films were synthesized by the RF plasma enhanced CVD method, and their oxidation behavior was studied up to $500^{\circ}C$ in air. The oxidation of both films was accompanied by evaporation of volatile species. The oxidation of BON film was preceded by nitrogen escape from the film, and oxygen penetration into the film. The oxidation of Si-DLC film was preceded by carbon escape probably as CO or $CO_2$from the film, and oxygen penetration into the film. The inwardly transported oxygen simply stayed in the oxidized BON and Si-DLC thin films.

• Journal of the Korean institute of surface engineering
• /
• v.54 no.6
• /
• pp.307-314
• /
• 2021

Diamond-like carbon (DLC) is difficult to achieve sufficient adhesion because of weak bonding between DLC film and the substrate. The purpose of this study is to improve the adhesion between substrate and DLC film. DLC film was deposited on AISI H13 using linear ion source. To improve adhesion, the substrate was treated by dual post plasma nitriding. In order to define the mechanism of the improvement in adhesive strength, the gradient layer between substrate and DLC film was analyzed by Glow Discharge Spectrometer (GDS) and Scanning Electron Microscope (SEM). The microstructure of the DLC film was analyzed using a micro Raman spectrometer. Mechanical properties were measured by nano-indentation, micro vickers hardness tester and tribology tester. The characteristic of adhesion was observed by scratch test. The adhesion of the DLC film was enhanced by active screen plasma nitriding layer.

• Journal of the Semiconductor & Display Technology
• /
• v.16 no.4
• /
• pp.1-4
• /
• 2017

Encapsulation of organic based devices is essential issue due to easy deterioration of organic material by water vapor. Atomic layer deposition (ALD) is a promising solution because of its low temperature deposition and quality of the deposited film. Moisture permeation has a mechanism to pass through defects, Thin Film Encapsulation using inorganic / organic / inorganic hybrid film has been used as promising technology. $Al_2O_3$ / Polymer / $Al_2O_3$ multilayer film has shown excellent environmental protection characteristics despite of thin thicknesses of the films.

• Elastomers and Composites
• /
• v.57 no.3
• /
• pp.114-120
• /
• 2022

The tensile properties of the extruded PC film were measured in the extrusion direction and perpendicular to the extrusion direction. The measured properties were the elastic modulus and Poisson's ratio at the glass transition temperature of PC. The measured orthotropic properties of the film were used for the computer simulation of vacuum forming. In this simulation, three mold shapes were tested: dome, trapezoid, and cubic, and the vacuum was applied between the mold surface and the heated film. The stress, strain, thickness, and stretch ratio distributions of the film in different mold shapes were observed and compared. The thermoforming simulation method used in this study and the obtained results, considering the determined orthotropic properties, can be applied to the thermoforming of various three-dimensional shapes.

• Korean Journal of Materials Research
• /
• v.8 no.2
• /
• pp.165-172
• /
• 1998

Epitaxial ultrathin films of $CoSi_2$ and double heteroepitaxial structure of Si/$CoSi_2$/Si(lll) were prepared on Si(111)-$7\times{7}$ substrate by in situ solid-phase epitaxy in a ultrahigh vacuum(LHV). The phase, chemical composition, crystallinity, and the microsructure of the Si/$CoSi_2$/Si(lll) interface were investigated by 2-MeV $^4He^{++}$ ion backscattering spectrometry, X-ray diffraction, and high-resolution transmission electron microscopy. The growth mode of the Co film was the Stransky-Krastanov type with texture when the substrate temperature was room temperature. A-type $CoSi_2$ ultrathin film was grown by deposition of about 50A Co on Si(ll1)-$7\times{7}$ substrate followed by in situ annealing at $700^{\circ}C$ for 10 min. The matching face relationships were $CoSi_2$[110]//Si[110] and $CoSi_2$(002)//Si(002) with no misorientation angle. The A-type $CoSi_2$/Si(lll) interface was abrupt and coherent. The best epi-Si/epi-$CoSi_2$2(A-type)/Si(lll) structure was obtained by deposition of Si film on the CoSii at $500^{\circ}C$ followed by in situ annealing at $700^{\circ}C$ for 10 min in UHV.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.14 no.7
• /
• pp.584-589
• /
• 2001

Diamond thin films were synthesized on WC-Co substrate by RF PACVD(radio frequency plasma-assisted chemical vapor deposition) technique with H$_2$-CH$_4$-O$_2$ gas mixture. WC-Co substrate was pre-treated in HNO$_3$solution, scratched with 3$\mu\textrm{m}$ diamond paste and exposed in the O$_2$ plasma before deposition. The diamond thin film prepared at 11% oxygen concentration showed the best quality of good adhesion and wear resistance at various oxygen concentration with the fixed 5% CH$_4$ concentration.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.11b
• /
• pp.300-303
• /
• 2001

BSCCO thin films are fabricated via a co-deposition process by an ion beam sputtering with an ultra-low growth rate, and sticking coefficients of the respective elements are evaluated. The sticking coefficient of Bi element exhibits a characteristic temperature dependence : almost a constant value of 0.49 below $730^{\circ}C$ and decreases linearly with temperature over $730^{\circ}C$. This temperature dependence can be elucidated from the evaporation and sublimation rates of bismuth oxide, $Bi_{2}O_{3}$, from the film surface. It is considered that the liquid phase of the bismuth oxide plays an important role in the Bi 2212 phase formation in the co-deposition process.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.13 no.1
• /
• pp.80-84
• /
• 2000

BSCCO thin films are fabricated via a co-deposition process by an ion beam sputtering with an ultra-low growth rate, and sticking coefficients of the respective elements are evaluated. The sticking coeffi-cient of Bi element exhibits a characteristic temperature dependence : almost a constant value of 0.49 below 73$0^{\circ}C$ and decreases linearly with temperature over 73$0^{\circ}C$. This temperature dependence can be elucidated from the evaporation and sublimation rates of bismuth oxide, Bi\ulcornerO\ulcorner, from the film surface. It is considered that the liquid phase of the bismuth oxide plays an important role in the Bi(2212) phase formation in the co-deposition process.