• Composites Research
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• 제29권5호
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• pp.269-275
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• 2016

Multiscale hybrid composites, which consist of polymeric resins, microscale fibers and nanoscale reinforcements, have drawn significant attention in the field of advanced, high-performance materials. Despite their advantages, multiscale hybrid composites show challenges associated with nanomaterial dispersion, viscosity, interfacial bonding and load transfer, and orientation control. In this paper, carbon nanotube(CNT)/carbon fiber(CF)/polycarbonate(PC) multiscale hybrid composite were fabricated by a solution process to overcome the difficulties associated with controlling the melt viscosity of thermoplastic resins. The dependence of CNT loading was studied by varying the method to add CNTs, i.e., impregnation of CF with CNT/PC/solvent solution and impregnation of CNT-coated CF with PC/solvent solution. In addition, hybrid composites were fabricated through surfactant-aided CNT dispersion followed by vacuum filtration. The morphologies of the surfaces of hybrid composites, as analyzed by scanning electron microscopy, revealed the quality of PC impregnation depends on the processing method. Dynamic mechanical analysis was performed to evaluate their mechanical performance. It was analyzed that if the position of the value of tan ${\delta}$ is closer to the ideal line, the adhesion between polymer and carbon fiber is stronger. The effect of mechanical interlocking has a great influence on the dynamic mechanical properties of the composites with CNT-coated CF, which indicates that coating CF with CNTs is a suitable method to fabricate CNT/CF/PC hybrid composites.

• 한국세라믹학회지
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• 제48권6호
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• pp.565-570
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• 2011

The $Eu^{3+}$ doped $Y(P_x,V_{1-x})O_4$ (0 ${\leq}$ x ${\leq}$ 1) phosphors were synthesized by solid-state and impregnation method and investigated as potential red-emitting phosphors for a plasma display panel(PDP). The optimal substitution proportion of P for V was determined to be 60 mol%, for $Y(P_x,V_{1-x})O_4$ doped with 8 mol% $Eu^{3+}$. The VUV PL spectra and SEM for the synthesized phosphors were measured and compared against those of a commercial red-emission phosphor. The $Y(P_x,V_{1-x})O_4$:$Eu^{3+}$ phosphors exhibited strong red at around 592, 618 and 698 nm. The emission intensity and particle size of the phosphors were controlled by preparation conditions.

• Journal of the Korean Wood Science and Technology
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• 제28권4호
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• pp.51-55
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• 2000

The woodceramics which are new porous carbon materials were obtained by carbonizing from thinned small log of Aomori HIBA (Thujopsis dolabrata S. et. Z. var. hondae M.) impregnated with phenol resin in a vacuum furnace. During the carbonization process, the resin changes into glassy carbon, which has superior property. The resin impregnation rate and bending strength depend on the types of board and density. In this paper, the manufacturing method of woodceramics made from thinned small logs of Aomori HIBA was introduced and some properties were examined.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1992년도 봄 학술발표회 논문집
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• pp.67-73
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• 1992

Polymer-Impregnated Concrete(PIC) is a new polymer-concrete composite material which consist of basic cement concrete and polymer. The mechanical properties and behavior of PIC depend on the type of polymers and the impregnation techniques. In general, the polymer impregnation can improve the strength, durability and ductility of normal concrete. The objective of this study is to develop the analytical procedure for analyzing the structural responces of polymer-impregnated concrete beams with different polymer loading by using finite element method on the basis of experimental results.

• 한국수소및신에너지학회논문집
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• 제17권4호
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• pp.440-447
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• 2006

Solid polymer electrolyte(SPE) membrane with electrodes embedded on both faces offer unique possibilities for the electrochemical cells like water electrolyzer with fuel cell. The Nafion 117 membrane was used as the SPE, and $Pt(NH_3)_4Cl_2$ and $NaBH_4$ as the electrocatalysts and reducing agent, respectively. The 'impregnation-reduction(I-R) method' has been investigated as a tool for the preparation of electrocatalysts for water electrolyzer by varying the concentration of reducing agent and reduction time at fixed concentration of platinum salt, 5 mmol/L. Pt-SPE electrocatalysts prepared by non-equilibrium I-R method showed the lowest cell voltage of 2.17 V at reduction time, 90 min and with concentration of reducing agent 0.8 mol/L and the cell voltage with those by equilibrium I-R method was 2.42 V at reduction time, 60 min and with concentration of reducing agent 0.8 mol/L. The cell voltage were obtained at a current density $1\;A/cm^2$ and $80^{\circ}C$. In water electrolysis, hydrogen production efficiency by Pt-SPE electrocatalyst is 68.2% in case of non-equilibrium I-R method and 61.2% at equilibrium I-R method.

• 한국분말재료학회지
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• 제28권1호
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• pp.7-12
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• 2021

The change in the open porosity of bulk graphite as a function of the uniaxial molding pressure during manufacturing is studied using artificial graphite powder. Subsequently, the graphite is impregnated to determine the effect of the open porosity on the impregnation efficiency and to improve the density of the final bulk graphite. Bulk graphite is manufactured with different uniaxial molding pressures after mixing graphite powder, which is the by-product of processing the final graphite products and phenolic resin. The bulk density and open porosity are measured using the Archimedes method. The bulk density and open porosity of bulk graphite increase as the molding pressure increases. The open porosity of molded bulk graphite is 25.35% at 30 MPa and 29.84% at 300 MPa. It is confirmed that the impregnation efficiency increases when the impregnation process is performed on a specimen with large open porosity. In this study, the bulk density of bulk graphite molded at 300 MPa is 11.06% higher than that before impregnation, which is the highest reported increase. Therefore, it is expected that the higher the uniaxial pressure, the higher the density of bulk graphite.

• 공업화학
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• 제17권4호
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• pp.369-374
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• 2006

Ethyl pyruvate의 비대칭 수소화 반응에 $Rh-Pt/Al_{2}O_{3}$ 이원금속 촉매를 처음으로 적용하고 그 반응특성을 조사하였다. $Rh-Pt/Al_{2}O_{3}$ 촉매는 상용 $Pt/Al_{2}O_{3}$에 Rh을 담지하거나 $Al_{2}O_{3}$에 Pt와 Rh을 연속적으로 함침시켜 제조하여, 촉매제법, Rh 함량 및 환원온도에 따라 반응속도, 광학선택도(ee%)가 변화하는 경향을 비교하였으며, XRD, TEM을 통하여 촉매의 물리적 특성을 분석하였다. $Rh-Pt/Al_{2}O_{3}$ 이원금속 촉매는 환원온도가 증가함에 따라 반응속도와 광학순도가 향상되었다(63.6 ee%). 또한 Rh의 함량에 따라서도 촉매 반응속도의 큰 변화를 보여주었는데, 그 변화 경향은 촉매 제조과정에 따라 달랐으나 광학선택도는 모든 이원촉매가 단일촉매에 비해 떨어지는 결과(56~60 ee%)를 나타내었다.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.661-662
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• 2006

Development of recycling method at cemented carbide scraps was researched. Some properties of recycled cemented carbides were investigated. Recycled WC fine powder suffered the surface oxidation. Therefore it was necessary to be done by reduction treatment at 1073K-3.6ks under hydrogen atmosphere. When sintering condition at 1673K-3.6ks was treated under vacuum condition, it gained the deflective strength of about 90%, and gained hardness and sintering density about same value compared with commercial alloys. As a result, it was able to recycle only by 7 processes.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.156.2-156.2
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• 2011

본 연구에서는 일단 수성가스전이반응 (Single stage water gas shift reaction)을 위해 높은 활성을 가진 백금 담지 촉매를 함침법 (Incipient wetness impregnation method)으로 제조하여 높은 공간 속도 (Gas hourly space velocity) $45,515h^{-1}$에서 담체에 따른 촉매 활성을 평가하였다. 담체는 $CeO_2$, $ZrO_2$, MgO, MgO-$Al_2O_3$ (MgO = 30 wt%) 그리고 $Al_2O_3$를 사용하였으며 백금의 담지량은 1 wt%로 고정하였다. BET, XRD, TPR, CO-chemisorption 분석을 통하여 담체의 구조적 특성이 촉매 활성에 미치는 영향에 대하여 조사하였다.

• Transactions on Electrical and Electronic Materials
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• 제9권2호
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• pp.57-61
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• 2008

The $(Y,Gd)_2O_3$:Eu phosphors were synthesized using the impregnation method in order to improve the performance of red-emitting phosphors for plasma display panels. $(Y,Gd)_2O_3$:Eu phosphors, with a particle size ranging from 150 and 200 nm, exhibited a strong red emission at around 615 nm. The emission intensity and particle size of the powders were controlled by adjusting the sintering temperature and raw material composition. The resulting particle size was very uniform and photoluminescence (PL) characteristic was excellent, being about twice that of commercial red phosphor.