• Elastomers and Composites
• /
• 제49권4호
• /
• pp.330-335
• /
• 2014

Niobium pentoxide ($Nb_2O_5$) 나노입자는 niobium (V) chloride 와 pluronic F108NF를 전구체와 주형제로 사용하여 합성하였다. $Nb_2O_5$-graphene나노복합체는 아르곤 가스 분위기 전기로 조건에서 2시간 동안 $700^{\circ}C$로 가열하였다. 시료의 결정화도, 결정형태, 광촉매 분해 반응성은 X-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV-vis spectroscopy를 사용하여 측정하였다. $Nb_2O_5$-graphene나노복합체는 254 nm의 자외선 조건에서 유기염료 광촉매 분해 반응의 광촉매로 사용되었다. 유기염료는 methylene blue (MB), methyl orange (MO), rhodamine B (RhB), brilliant green (BG)이 사용되었다. 또한 $Nb_2O_5$-graphene나노복합체를 사용하여 유기염료 광촉매 분해 반응의 반응 속도를 결정하였다.

• Elastomers and Composites
• /
• 제38권3호
• /
• pp.273-280
• /
• 2003

본 연구에서는 분자량이 다른 순수 천연고무 용융체와 다양한 유형의 카본블랙을 혼합한 배합고무 용융체의 탄성반응을 조사하였다. 또한 카본블랙과 고무 분자와의 상호작용과 이들 탄성반응이 갖는 상관성을 규명키 위해 입자의 크기와 구조가 다른 카본블랙을 대상으로 결합고무를 측정하였다. 카본블랙의 함량이 증가할수록 결합고무는 증가하였고 특히 카본블랙 입자의 크기가 작아 비표면적이 넓고 구조가 발달될수록 증가하였다. 카본블랙을 혼합한 배합고무 용융체의 탄성반응은 순수고무 경우에 비해 크게 향상되었으며 특히 결합고무가 큰 경우에 보다 현저하였다. 순수고무 용융체의 분자량이 증가할수록, 그리고 고무에 혼합된 카본블랙 입자의 크기가 작을수록 응력이완 거동은 지연되었으며 복원거동은 보다 탄성적으로 변하였다. 영구변형 거동에 있어서는 고무 분자량이 감소하고 카본블랙 입자 크기가 증가할수록 그 변형정도가 커졌다.

• Composites Research
• /
• 제35권2호
• /
• pp.80-85
• /
• 2022

본 연구에서는 항공기 방빙을 위해서 탄소계 소수성 입자인 탄소나노튜브의 코팅 횟수에 따른 테프론-폴리우레탄 탑코트의 나노입자 부착력과 표면 소수성 특성을 평가하기 위하여 실험을 진행하였다. 나노입자 부착력을 측정하기 위해서 인발접착시험을 진행하였고, 표면소수성 특성을 측정하기 위해서 정적접촉각 시험과 거칠기 평가를 진행하였다. 거칠기평가를 통하여 탄소나노튜브가 테프론-폴리우레탄 탑코트에 함침된 정도를 할 수 있었고, USB-현미경을 통하여 테프론-폴리우레탄 탑코트에 탄소나노튜브가 함침 및 분산정도를 확인하였다. 그 결과 코팅횟수가 많을수록 탄소나노튜브가 응집되고 이에 의하여 접착력이 감소한다는 것을 확인하였다. 실험결과 코팅 횟수에 따라 테프론-폴리우레탄의 소수성은 커지고 접착력은 감소하였다. 그로 인해 테프론-폴리우레탄 탑코트 와의 접착력 향상과 최적화된 소수성을 가지는 탄소나노튜브의 코팅횟수를 파악할 수 있었다.

• 한국해양공학회:학술대회논문집
• /
• 한국해양공학회 2004년도 학술대회지
• /
• pp.380-385
• /
• 2004

The efficiency of complex slurry preparation route for developing the high performance SiC matrix of RS-SiCf/SiC composites has been investigated. The green bodies for RS-SiC materials prior to the infiltration of nw/ten silicon were prepared with various C/SiC complex matrix slurries, which associated with both different sizes of starting SiC particles and blending ratios of starting SiC and carbon particles. The characterization of RS-SiC materials was examined by means of SEM, TEM, EDS and three point bending test. Based on the mechanical property-microstructure correlation, process optimization methodology is also discussed. The flexural strength of RS-SiC materials greatly depended on the content of residual Si. The decrease of starting SiC particle size in the C/SiC complex slurry was effective for improving the flexural strength of RS-SiC materials.

• 한국세라믹학회지
• /
• 제53권1호
• /
• pp.56-62
• /
• 2016

A heterogeneous $Bi_2S_3/TiO_2$ composite catalyst was synthesized via a green ultrasonic-assisted method and characterized by XRD, SEM, EDX, TEM analysis. The results clearly show that the $TiO_2$ particles were homogenously coated with $Bi_2S_3$ particles, indicating that $Bi_2S_3$ particle agglomeration was effectively inhibited after the introduction of anatase $TiO_2$. The Texbrite BA-L (TBA) degradation rate constant for $Bi_2S_3/TiO_2$ composites reached $8.27{\times}10^{-3}min^{-1}$ under visible light, much higher than the corresponding value of $1.04{\times}10^{-3}min^{-1}$ for $TiO_2$. The quantities of generated hydroxyl radicals can be analyzed by DPCI degradation, which shows that under visible light irradiation, more electron-hole pairs can be generated. Finally, the possible mechanism for the generation of reactive oxygen species under visible-light irradiation was proposed as well. Our result shows the significant potential of $Bi_2S_3$-semiconductor-based $TiO_2$ hybrid materials as catalysts under visible light for the degradation of industry dye effluent substances.

• Composites Research
• /
• 제13권1호
• /
• pp.25-32
• /
• 2000

국부압축력을 받는 스트링거 보강 복합적층 만곡 판넬의 좌굴 및 후좌굴 거동을 개발한 유한요소프로그램을 이용하여 해석하였다. 후좌굴 해석은 판넬거동을 세 가지로 나누어 해석하였다. 판넬과 보강재를 모델링 하기 위하여 8절점응축 쉘요소를 도입하고 비선형유한 요소 수식화를 위해 2nd Piola-Kirchhoff 응력텐서와 Lagrangian 변형률 텐서를 채택하였다. 파손 특성을 고려하기 위해 점진적 파손해석을 도입하였다. 국부축하중을 받는 복합적층 만곡 판넬의 좌굴하중 및 좌굴후 극한하중, 국부좌굴과 전체좌굴, 그리고 보강재 영향이 인자별로 해석 비교 된다.

• 한국전기전자재료학회논문지
• /
• 제15권3호
• /
• pp.269-274
• /
• 2002

(Sm/Y)-Ba-Cu-O system high Tc composite superconductors with/without $CeO_2$ additive were directionally grown by zone-melting process, haying large temperature gradient, In air atmosphere. Cylindrical green rods of $({Sm/y})_{1.8}Ba_{2.4}Cu_{3.4}O_x$ [(Sm/Y)1.8] composite oxides by cold isostatic pressing(CIP) method using rubber mold were fabricated. The microstructure and superconducting properties were investigated by XRD, SEM, TEM and SQUID magnetometer. The size of nonsuperconducting $({Sm/y})_2BaCuO_5$ inclusions of the melt-textured (Sm/Y)1.8 sample with CeO$_2$ additive were remarkably reduced and uniformly distributed within the superconducting (Sm/Y)1.8 matrix. Both samples, with/without $CeO_2$ additive, showed an onset Tc $\geq$ 90 K and sharp superconducting transition. The critical current density Jc value of the $CeO_2$ addictive were $1{\times}10^5A/\textrm{cm}^2$ in 77 K, 0 Tesla.

• Elastomers and Composites
• /
• 제50권2호
• /
• pp.126-131
• /
• 2015

$C_{60}$ nanowhiskers were synthesized from $C_{60}$ by liquid-liquid interfacial precipitation (LLIP) using $C_{60}$-saturated toluene and isopropyl alcohol. The $WO_3$ nanoparticles were synthesized by adding $3.8{\times}10^{-4}$ mole amount of ammonium metatungstate hydrate ($H_{26}N_6O_{40}W_{12}{\cdot}H_2O$) to 500 ml of distilled water, and the resulting solution was heated on a hot plate for 4 h. The $C_{60}$ nanowhiskers/$WO_3$ nanocomposites were prepared with $C_{60}$ nanowhiskers and $WO_3$ nanoparticles in an electric furnace at $700^{\circ}C$ in an argon gas atmosphere for 2 h. The $C_{60}$ nanowhiskers/$WO_3$ nanocomposites were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. UV-vis spectroscopy was used to evaluate the performance of the $C_{60}$ nanowhiskers/$WO_3$ nanocomposites as a photocatalyst in the degradation of organic dyes, such as methylene blue (MB) and brilliant green (BG) under ultraviolet light (254 nm).

• Elastomers and Composites
• /
• 제51권4호
• /
• pp.286-300
• /
• 2016

$MoS_2$ precursors were synthesized by reacting thioacetamide ($C_2H_5NS$) with sodium molybdate dihydrate ($Na_2MoO_4{\cdot}2H_2O$) in aqueous HCl solution. $MoS_2$ nanoparticles were prepared from dried $MoS_2$ precursors by calcination in an electric furnace at $700^{\circ}C$ for 2 h under an inert argon atmosphere. $MoS_2-C_{60}$ nanocomposites were obtained by heating $MoS_2$ nanoparticles and fullerene ($C_{60}$) together in an electric furnace at $700^{\circ}C$ for 2 h. Their morphological and the structural properties were characterized by powder X-ray diffraction and scanning electron microscopy. The $MoS_2$ nanoparticles and $MoS_2-C_{60}$ nanocomposites were used as catalysts in the reductions of 2-, 3-, and 4-nitrophenol in the presence of sodium borohydride. The photocatalytic activities of the $MoS_2$ nanoparticles and $MoS_2-C_{60}$ nanocomposites were evaluated in the degradation of organic dyes (brilliant green, methylene blue, methyl orange, and rhodamine B) under ultraviolet light (254 nm).

• 한국전기전자재료학회논문지
• /
• 제29권2호
• /
• pp.110-113
• /
• 2016

(YNdSm)-Ba-Cu-O system high Tc composite superconductors were directionally grown by zone melting process, having large temperature gradient, in air atmosphere. Cylindrical green rods of $(YNdSm)_{1.8}Ba_{2.4}Cu_{3.4}O_x$ [(YNS)1.8]composite oxides by CIP (cold isostatic pressing) method using rubber mold were fabricated. The microstructure and superconducting properties were investigated by XRD, TEM and SQUID magnetometer. The size of nonsuperconducting $(YNdSm)_2BaCuO_5$ inclusions of the melt-textured (YNS)1.8 sample with $CeO_2$ additive were remarkably reduced and uniformly distributed within the superconducting (YNS)1.8 matrix. (YNS)1.8 samples, with / without $CeO_2$ additive, showed an onset $T_c{\geq}90K$ and sharp superconducting transition. The critical current density $J_c$ value of the (YNdSm)1.8 superconductor with $CeO_2$ additive were 840 A, $1.2{\times}104A/cm^2$ in 77 K, 0 Tesla by direct current transport method.