• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.05a
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• pp.71-71
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• 2015

TiN 박막의 미세구조를 공정 변수인 기판 전압, 기판과 타겟의 각도 등을 이용하여 변화시켜 박막의 물리적 특성을 평가하였다. TiN 박막은 음극 아크 증착법을 이용하여 기판에 코팅하였다. TiN 박막은 기판과 타겟의 각도를 제어하면 기판에 수직한 주상과 일정한 각도를 갖는 주상으로 성장하는 것을 확인하였다. 기판과 타겟의 각도를 일정하게 유지한 경우에도 기판에 전압을 인가하면 TiN 박막의 주상이 기판과 수직하게 성장하는 것을 확인하였다. 기판과 타겟의 각도와 기판 전압을 활용하면 TiN 박막의 미세구조를 다양하게 변화시킬 수 있었다. TiN 박막의 미세구조 변화는 물리적 특성 변화에 영향을 준 것으로 판단되며 기판 전압과 각도를 인가하지 않은 TiN 박막보다 미세구조가 변화한 박막이 높은 경도를 보였다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.05a
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• pp.159-159
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• 2015

금속의 기계적 강화방법인 결정립미세화의 일종으로 미세한 쌍정을 도입하여 기계적강도를 향상시키면서 전기전도도는 감소시키지 않는 방안으로 nanotwin 구조의 Cu가 보고되고 있다. Nanotwin 구조는 FCC결정구조에서 특정 결정면을 [(111) mirror plane]을 기준으로 정합계면을 유지하면서 원자층의 배열이 역전되는 구조가 수~수십나노 수준의 간격으로 이뤄진 미세조직을 의미한다. 전해도금법을 이용한 nanotwin Cu의 형성방법으로는 pulse 파형을 사용하는데, pulse파형의 on time동안의 높은 전류밀도로 인해 발생한 도금층의 stress가 off time동안에 release되면서 nanotwin구조가 형성되는 것으로 보고되고 있다. Nanotwin형성 조건으로 보고된 pulse 도금 조건은 수에서 수십밀리초의 on time에 duty cycle($t_{on}/(t_{off}+t_{on})$)이 1/100~1/10 수준이다. 본 연구에서는 전기이중층의 이온고갈에 필요한 회복시간인 수에서 수십 밀리초 보다 짧은 시간인 마이크로 초($1{\mu}s$, $10{\mu}s$ 및 $100{\mu}s$)의 pulse 전류를 인가하였을 때에 발생하는 구리 도금층의 미세조직의 변화에 대해 알아보고자 한다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.63-66
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• 1999

The effects of UV and ozone on the weathershed materials for 5 polymer insulators were investigated. This study was carried by material characterizations such as surface microstructure, thermal property, chemical structure and contact angle. The aged specimens are compared with new ones. In case of UV, the chalking of fillers and cracking of surface were increased with the increase of UV radiation time. In case of ozone, aged specimens are not different from new ones. From this study, It can be concluded that UV has more effect on the surface properties of weathershed materials than ozone.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.238-239
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• 2005

With the aim of developing XLPE insulation for extra high voltage cable, we investigated the morphology of cross-linked polyethylene. We used a kind of base materials and additives, and controlled curing condition and amount of additives. The effect of addition of additives on morphology of XLPE such as lamellar density, orientation and additive layer were analyzed using TEM analysis. We applied this result to diffused additive amount was analyzed using FT-IR analysis, and the change of microstructure as the degree of additive diffusion was analyzed using TEM analysis.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.633-634
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• 2005

Transparent conducting glasses exhibit high ohmic losses that are apparent in the case of large size Dye Sensitized Solar Cells (DSSCs). In this study, we investigated the impact of current collectors over the efficiency of DSSCs. The Silver current collectors were prepared on both counter electrode and working electrode surface by screen printing method. For long term stability in electrolyte environment and also to avoid the charge recombination, current collectors are protected by sodium silicate overcoat layer. These current collectors were characterized for their microstructure parameters. Also current collector's stability in electrolyte environment has been investigated.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.11
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• pp.943-947
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• 2007

The effect of hydrogen and oxygen plasma treatments on the structural properties of carbon nanotube(CNT) has been systematically investigated. As the plasma power was increased, nano particles were appeared at the surface of CNTs. At high plasma power(300 Watt), the structure of CNT was changed from nanotube type to nano particles. However, in case of hydrogen plasma treatment, there was no change in microstructure of CNT. From the Raman analysis, the crystallinity of CNT was deteriorated by the plasma treatment, regardless of gas types.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1996.04b
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• pp.20-24
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• 1996

Three kinds of the sialon ceramics with and without TiN additions were hot pressed. Hardness and fracture toughness were measured with prepared specimens to study the effect of additives on the mechanical properties. A gas blast type erosion tester was employed to examine erosion behavior of the specimens up to 600 $^{\circ}$C. Erosion tests showed an increase of erosion rate up to 400 $^{\circ}$C and a gradual decrease of erosion rate 500 $^{\circ}$C for all kinds of sialon. The results also showed that erosion rates of the sialons were controlled better by microstructure factors than by mechanical properties such as fracture toughness.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1996.04b
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• pp.13-19
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• 1996

The tribological properties of the aluminum short fiber and glass fiber reinforced tin-bronze matrix composites manufactured by vacuum hot pressing was studied. The effect of the composition and the relative density on the wear properties was examined by a reciprocal type tribo-test machine. The results were discussed by the observation of the microstructure of sintered specimen and worn surface observation using SEM and EDS. Addition of the fibers led to the wear resistance since the metal matrix was reinforced by the fibers. The reinforcement of the fiber seemed to be stronger as the distribution of the fibers was more uniform. Graphite also reduce the wear loss. The pores in the sintered composites seemed to play an important role to improve the wear resistance since the pores provide the places where the solid lubricants locate.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2000.11a
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• pp.304-309
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• 2000

Si$_3$N$_4$-6wt%Y$_2$O$_3$-lwt%Al$_2$O$_3$was prepared by hot pressed and gas pressure sintering to investigate the effect of microstructure on erosion behaviors. Hardness and fracture toughness were measured with prepared specimens to study the high temperature erosion properties. A gas blast type erosion tester was used In examine erosion behavior of the specimens up to 700$^{\circ}C$. In case of GPS silicon nitride, the erosion rate increases up to 500$^{\circ}C$ and decreases over 500$^{\circ}C$. Maximum erosion rate was observed at 300$^{\circ}C$ for HP silicon nitride. The principal factors affecting the high temperature erosive wear of brittle materials are largely dependent on high temperature properties of grain boundaries.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.233-236
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• 2005

Rotor in small-medium induction motor has been usually manufactured by aluminum diecasting. In order to improve efficiency of induction motors, newly developed Cu-Ca alloys have been investigated. The electrical conductivity in the Cu alloys containing Ca less than $1.0wt\%$ was higher than $80\%$ IACS. Cu-Ca alloy is desirable for the thixoforming process because it has wide semi-solid range over $150^{\circ}C$. In this study, Cu-rotor with thixoforming process was developed to replace the conventional aluminum diecasting rotor. Analysis microstructure of thixoforming rotor. effect of incomplete filling defect on the efficiency of induction motor was discussed.