• Journal of Surface Science and Engineering
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• v.25 no.6
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• pp.299-308
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• 1992

Titanium nitride(TiN) has been synthesized by nitrogen ion irradiation onto the Ti thin film deposited on STD11 and SKH9 tool materials. The effect of irradiation flux and substrate temperature on the formation behavior and mechanical properaties of TiN were investigated through X-ray diffraction analysis, hardness and pin-on-disc wear testings. Nitrogen ion irradiation onto arc evaporated Ti thin film produced TiN of < 200> orientation at elevated temperature and thereby enhancing surface microhardness by 50% at maximum. Wear resistance was also improved by nitrogen irradiation at most process conditions. The enhancement of wear resistance appeared to be more effective for the nitrogen irradiated conditions at room temperature than at elevated temperature.

• Journal of the Korean Ceramic Society
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• v.43 no.8 s.291
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• pp.492-497
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• 2006

SiC coating has been introduced as protective layer in TRISO nuclear fuel particle of High Temperature Gas cooled Reactor (HTGR) due to excellent mechanical stability at high temperature. In order to inhibit the failure of the TRISO particles, it is important to evaluate the fracture strength of the SiC coating layer. ]n present work, thin silicon carbide coating was fabricated using chemical vapor deposition process with different microstructures and thicknesses. Processing condition and surface status of substrate.affect on the microstructure of SiC coating layer. Sphere indentation method on trilayer configuration was conducted to measure the fracture strength of the SiC film. The fracture strength of SiC film with different microstructure and thickness were characterized by trilayer strength measurement method nanoindentation technique was also used to characterize the elastic modulus and th ε hardness of the SiC film. Relationships between microstructure and mechanical properties of CVD SiC thin film were discussed.

• Korean Journal of Materials Research
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• v.14 no.8
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• pp.558-564
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• 2004

In order to improve the low hardness and low wear resistance of Ti-6Al-4V alloy, plasma carburization treatment and CrN film coating were carried out. Effects of the plasma carburization and CrN coating were analyzed and compared with the non-treated alloy by mechanical and creep tests. After plasma carburization and CrN coating treatments, the carburized layer was about 150 ${\mu}m$ in depth and CrN coated layer was about 7.5 ${\mu}m$ in thickness. Hardness value of about $H_{v}$ 402 of the non-treated alloy was improved to $H_{v}$ 1600 and 1390 by plasma carburization and CrN thin film coating, respectively. Stress exponent(n) was decreased from 9.10 in CrN coating specimen to 8.95 in carburized specimen. However, the activation energy(Q) was increased from 242 to 250 kJ/mol. It can be concluded that the static creep deformation for Ti-6Al-4V alloy is controlled by the dislocation climb over the ranges of the experimental conditions.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.165-166
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• 2002

Hydrogen free diamond like carbon (DLC) films were prepared on steel substrates by using a single ion beam in a configuration that allowed sputtering of a graphite target and at the same time allowed to impact the substrate at a grazing angle. The DLC films so prepared have improved properties with increased disorder and with modest hardness that is slightly higher than previously reported values. We have studied the effects of $N_2^+$ ions implantation on such films. It is found that the implantations of nitrogen ions into DLC films lead to chemical modifications that allowed N atoms to be incorporated into the carbon network to produce a nitrogenated DLC. Nano-indentation experiments indicated that the nitrogenated films have consistently higher hardnesses ranging from 30 to 45GPa, which represents a considerable increase in surface hardness, compared with non-nitrogenated precursor films. The investigations by XPS and Raman spectroscopy suggests that the $N_2^+$ implanted DLCs had undergone both chemical and structural modifications through the incorporation of N atoms and the increased ratio of $sp^3/sp^2$ type bonding. The observed high hardness was therefore attributable to these structural and chemical modifications. This result has implication for the preparation of super hard wear resistant films required for tribological functions in devices.

• Journal of the Microelectronics and Packaging Society
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• v.27 no.3
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• pp.83-88
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• 2020

The evolution of smartphones has led to numerous researches in the mechanical behavior of flexible devices. Due to the nano-size of the thin flexible film, nanoindentation is widely used to evaluate its mechanical behaviors, such as elastic modulus, and hardness. However, the commonly used Oliver-Pharr method is not suited for analyzing the indentation force-depth curves of hard films on soft substrates, as the effects of soft substrate is not considered theoretically. In this study, the elastic modulus of the thin film was evaluated with references to other reported models which include the substrate effect, and with calibration of the indentation depth for the pile-ups between the indenter and test surface. We fabricated test samples by deposition of amorphous metal film on polyimide and silicon wafers for verification of modified models.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.429-429
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• 2007

For various applications of liquid crystal displays (LCDs), the uniform alignment of liquid crystal (LC) molecules on treated surfaces is significantly important. Generally, a rubbing method has been widely used to align the LC molecules on polyimide (PI) surfaces. Rubbed PI surfaces have suitable characteristics, such as uniform alignment. However, the rubbing method has some drawbacks, such as the generation of electrostatic charges and the creation of contaminating particles. Thus, we strongly recommend a non contact alignment technique for future generations of large high-resolution LCDs. Most recently, the LC aligning capabilities achieved by ultraviolet and ion-beam exposures which are non contact methods, on diamond-like carbon (DLC) inorganic thin film layers have been successfully studied because DLC thin films have a high mechanical hardness, a high electrical resistivity, optical transparency, and chemical inertness. In addition, nitrogen-doped DLC (NDLC) thin films exhibit properties similar to those of the DLC thin films and a higher thermal stability than the DLC thin films because C:N bonding in the NDLC thin filmsis stronger against thermal stress than C:H bonding in the DLC thin films. Our research group has already studied the NDLC thin films by an ion-beam alignment method. The $SiN_x$ thin films deposited by plasma-enhanced chemical vapor deposition are widely used as an insulation layer for a thin film transistor, which has characteristics similar to those of DLC inorganic thin films. Therefore, in this paper, we report on LC alignment effects and pretilt angle generation on a $SiN_x$, thin film treated by ion-beam irradiation for various N ratios

• Journal of Surface Science and Engineering
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• v.40 no.1
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• pp.1-5
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• 2007

Quaternary TiZrAlN nanocomposite thin films were synthesized by Closed-Field Unbalanced Magnetron Sputtering (CFUBMS), and their microstructure and mechanical characteristics were examined. The grain refinement of the TiZrAlN nanocomposite thin films was controlled by adjusting the $N_2$ partial pressure. The hardness of the film varied with the $N_2$ partial pressure and the maximum value was obtained approximately 47 GPa. It was also confirmed that there is a critical value of the grain size($d_c$) to need maximum hardness.

• Journal of the Korean Vacuum Society
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• v.20 no.5
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• pp.333-338
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• 2011

In this work, we have fabricated the amorphous carbon (a-C:H) thin film by using unbalanced magnetron sputtering method with the magnetron source of inside/outside electromagnetic coils as the protective coating materials. We have investigated the tribological properties of amorphous carbon films prepared with various electromagnetic coil currents for the change of the plasma density, such as hardness, friction coefficient, adhesion, and surface roughness. Raman and HRTEM were used to study the microstructure of carbon films. In the result, the hardness and adhesion properties of a-C:H films were improved with increasing electromagnetic coil current due to the increase of the plasma density to the substrate. Thus, these results can be explained by the increase of $sp^2$ bonding and cluster number in the amorphous carbon film, related to the improved bombardment around substrate and the increased substrate temperature.

• Polymer(Korea)
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• v.37 no.5
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• pp.587-591
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• 2013

Poly(3,4-ethylenedioxythiophene) (PEDOT) has good properties such as high conductivity, optical transmittance, and chemical stability, while offering relatively weak physicochemical properties. The main purpose of this paper is the improvement of physicochemical properties such as solvent resistance and pencil hardness of PEDOT. Carboxyl groups in the anionic type waterborne polyurethane (WPU) chains can effectively crosslink each other in the presence of aziridine, resulting in physicochemically robust PEDOT/WPU organic-organic hybrid conductive thin films. The electrical conductivity, optical properties, and physicochemical properties of the hybrid conductive film were compared by varying the solid content and WPU portion in the coating precursor solution. From the results, the transparency and surface resistance of the hybrid film show a decreasing tendency with increasing solid content in the coating precursor. Moreover, solvent resistance and hardness were dramatically enhanced by hybridization of PEDOT and crosslinked WPU due to curing reactions between carboxyl groups.

• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.851-853
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• 1999

DLC thin films have been fabricated by pulsed laser deposition with various deposition parameters. The characterization of fabricated thin films was performed depending on the deposition parameters. As the kinetic energies provided by deposition temperature and the laser energy density were increased, the film showed graphite properties. Structural properties of the films were investigated by Raman spectroscopy. The growth energy should be optimized to fabricate high quality DLC thin films. DLC films showed high hardness and their friction coefficient was measured to be about 0.2 regardless of the load of the ball pin.