• Composites Research
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• v.16 no.2
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• pp.18-25
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• 2003

The tensile properties of short nylon6 fiber reinforced NR and SBR have been investigated as functions of fiber aspect ratio(AR), diameter ratio(DR), interphase condition, and fiber content. The tensile strength increased with increasing fiber AR(20 min.) and good interphase conditions. The short-fiber(DR=3 and AR=20 min.) reinforced SBR did not show the dilution effect for all interrhase conditions. And the short-fiber(DR=3 and AR=20min.) reinforced NR did not show the dilution effect except for the no-coating. The tensile moduli were significantly improved due to fiber AR. fiber content, and good interphase at same DR. The better interphase condition showed the higher pull-out force at same DR. Also, the stress analysis near the fiber end carried out using axisymmetric FEA to be convinced of the reinforcing mechanism. It is found that the fiber AR, interphase and DR have an important effect on tensile properties.

• Tribology and Lubricants
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• v.20 no.5
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• pp.237-244
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• 2004

Micro/nano tribological characteristics of PTFE coating films were experimentally studied. PTFE (polytetrafluoroethylene) modified polyethylene and low molecular weight PTFE were used as a coating materials. These films were deposited on Si-wafer (100) by IBAD (ion beam assisted deposition) method. The Ar ion beam sputtering was performed to change the surface topography of films using a hollow cathode ion gun under different Ar ion dose conditions in a vacuum chamber. Micro/nano tribological characteristics, water wetting angles and roughness were measured with a micro tribotester, SPM (scanning probe microscope), contact anglemeter and profilometer, respectively. The durability of the films were measured with macro tribotester. Results showed that the PTFE coating surfaces were converted to hydrophobic. The water contact angle of coated surfaces and surface roughness increased with the coating thickness. Adhesion and friction in micro and nano scale were governed by magnitude of normal load in soft material such as PTFE films. As the increase of sputtering time on low molecular weight PTFE films, the surface roughness was increased and nano adhesion and friction were decreased. The nano tribological characteristics of surfaces are mainly improved by chemical modification such as PTFE coating and given a synergy effect by the physical modification such as topographic modification.

• Journal of the Korean Vacuum Society
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• v.19 no.5
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• pp.341-346
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• 2010

In this paper, anti-reflection coating was investigated for decreasing the reflection in visible range of 400~650 [nm] through four staked layers of $Si_xO_y$ and $Si_xN_y$ thin films prepared by reactive sputtering method. Si single crystal of 6 [inch] diameter was used as a sputtering target. Ar and $O_2$ gases were used as sputtering gases for reactive sputtering for the $Si_xO_y$ thin film, and Ar and $N_2$ gases were used for reactive sputtering for the $Si_xN_y$ thin film. DC pulse power of 1900 [W] was used for the reactive sputtering. Refractive index and deposition rate were 1.50 and 2.3 [nm/sec] for the $Si_xO_y$, and 1.94 and 1.8 [nm/sec] for the $Si_xN_y$ thin film, respectively. Considering the simulation of the four layer anti-reflection coating structure with the above mentioned films, the $Si_xO_y-Si_xN_y$ stacked four-layer structure was prepared. The reflection measurement result for that structure showed that a "W" shaped anti-reflection was obtained successfully with a reflection of 1.7 [%] at 550 [nm] region and a reflection of 1 [%] at 400~650 [nm] range.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.30 no.2
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• pp.66-72
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• 2020

The difference of plasma resistance between the CAS glass bulk and coating films were compared. Plasma resistance was confirmed by analyzing the etch rate and the microstructure of the surface when the CAS glass bulk and the glass coating film were etched with CF₄/O₂/Ar plasma gas. CAS glass coating film was etched up to 25 times faster than the glass bulk. A statistically high correlation between the surface roughness and the etching rate of the coating film was derived, and thus, the high surface roughness of the coating film was determined to cause rapid etching. In addition, cristobalite crystals that has a low Ca content and a high Si content, was foamed on the glass coating film. Therefore, the CAS glass coating film is considered to have low plasma resistance compared to the glass bulk.

• Journal of the Korean institute of surface engineering
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• v.55 no.6
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• pp.376-382
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• 2022

Yb₂Si₂O₇ has a coefficient of thermal expansion similar to that of the base material of SiC and has excellent corrosion resistance in a high-temperature oxidizing atmosphere including water vapor, so it is being studied as one of the materials for environmental barrier coatings (EBCs). In this study, Yb₂Si₂O₇ powder granule is deposited using atmospheric plasma spraying (APS) with different Ar/He ratios. Phase formation and microstructural characteristics are investigated with the coated specimens. In the coating layer, the crystallinity decreased, and the amorphous content increased from an increase in the ratio of Ar. In addition, the various types of particles involved by local volatilization of Si according to the Ar/He ratios were identified.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.3
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• pp.248-251
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• 2009

We have investigated the effect of the quality of 1.3 um distributed feed back laser diode (DFB-LD) on the design of anti-reflection (AR) coatings. Optimal condition of AR coating to prevent internal feedback from both facets and reduce the reflection-induced intensity noise of laser diode was simulated with Macleod Simulator. Coating materials used in this work were ${Ti_3}{O_5}$ and $SiO_2$, of which design thickness were 105 nm and 165 nm, respectively. AR coating films were deposited by Ion-Assisted Deposition system. The electrical and optical properties of 1.3 um laser diode were characterized by Bar tester and Chip tester. Threshold current and slop-efficiency of DFB-LD were 27.56 mA 0.302 W/A. Far field pattern and wavelength of DFB-LD were $22.3^{\circ}(Horizontal){\times}24.4^{\circ}$ (Vertical), 1313.8 nm, respectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.1
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• pp.61-66
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• 2002

A method for designing antireflection (AR) and antistatic (AS) coating layer by the use of conducting polymer as an electrically conductive transparent layer is proposed. The conducting AR coating is composed of four-layer with alternating high and low refractive index layer: silicon dioxide (n=1.44) and titanium dioxide (n=2.02) prepared at low temperature by sol-gel method are used as the low and high refractive index layer, respectively. The poly(3,4-ethylenedioxythiophene) which has the surface resistivity of 10$^4$Ω/$\square$ is used as a conductive layer. Optical constant of each ARAS coating layers such as refractive index and optical thickness were measured by 7he spectroscopic ellipsometer and from the measured optical constants the spectral properties such as reflectance and transmittance were simulated in the risible region. The reflectance of ARAS films on glass substrate was below 1 %R and the transmittance was higher than 95 % in the visible wavelength (400-700 nm). The measured AR spectral properties was very similar to its simulated results.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.04c
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• pp.80-81
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• 2008

In this paper, we have designed the Anti-Reflection (AR) coating for 850, 1310 nm(multi type) and 1310, 1550 nm(multi type) wavelength ranges on the ferrule facet of special optical connector. The reflectance of the AR coated ferrule facet is designed under 5% for 850, 1310 nm(multi type) and 1310, 1550 nm (multi type). The average return loss of the AR coated ferrule facet is 47.1 dB.

• Korean Journal of Materials Research
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• v.7 no.1
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• pp.3-7
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• 1997

VO$_{2}$ 써모크로믹 원도우의 가시광 투과율을 높히기 위하여 내마모성이 우수한 SiO$_{2}$박막을 이용하여 AR(anti-rdflection)코팅을 하였다. 두가지 중요한 공정변수인 기판온도와 증착속도가 AR효과에 미치는 영향을 조사하였다. 그리고 SiO$_{2}$박막의 AR효과는 낮은 기판온도와 높은 증착속도에서 더 우수한 것으로 나타났으며, 이는 SiO$_{2}$AR 박막의 굴절율과 상관관계가 있는 것으로 나타났다. VO$_{2}$ 써모크로믹 유리 위에 SiO$_{2}$AR-코팅을 했을 때 약 30% 정도의 가시광 투과율의 향상이 있었다. 그리고 AR-코팅을 하지 않은 경우보다 더 뚜렷한 써모크로미즘을 나타냈다. 또한 천이온도는 7$0^{\circ}C$정도로 AR-코팅을 하지 않은 VO$_{2}$써모크로믹 유리의 경우와 같게 나타났다.

• Journal of the Korean institute of surface engineering
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• v.52 no.2
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• pp.84-89
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• 2019

We fabricated durable anti-reflective(AR) layer with silica globular coating on polymer by two steps. Firstly, nano-protrusions of polymer were formed by plasma etching known as R.I.E(reactive ion etching) process. Secondly, silica globular coating was deposited on polymer nano-protrusions for mechanically protective and optically enhancing AR layers by RF magnetron sputter. And then durable antireflective polymers were synthesized adjusting plasma power and time, working pressures of RIE and RF sputtering processes. Consequently, we acquired the average transmission (94.10%) in the visible spectral range 400-800 nm and the durability of AR layer was verified to sustain its transmission until 5,000 numbers by rubber test at a load of 500 gf.