• Korean Chemical Engineering Research
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• 제55권2호
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• pp.264-269
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• 2017

피치계 흑연섬유의 발열특성을 향상시키기 위하여 흑연섬유에 무전해법을 이용하여 구리 도금하였다. 구리 도금된 흑연섬유는 공기 분위기에서 열중량분석법을 실시하여 도금 시간에 따라 흑연섬유 표면에 구리가 도입된 양을 계산하였다. 또한, 전압에 따른 발열 온도는 섬유 가닥을 이용하여 열화상카메라로 관찰하였다. 무전해 도금의 시간이 증가함에 따라 도입된 구리의 양은 증가하였다. 20분 동안 무전해 도금한 섬유의 전기 전도도는 1594.3 S/cm이며, 발열 온도는 최대 $57.2^{\circ}C$로 가장 크게 나타났다. 이러한 결과는 도금시간이 증가함에 따라 전기 전도성이 우수한 구리가 흑연섬유 표면에 성장하고, 이에 따라 발열특성이 향상된 것으로 판단된다.

• Computers and Concrete
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• 제12권3호
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• pp.337-349
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• 2013

Traditional concrete is effectively an insulator in the dry state. However, conductive concrete can attain relatively high conductivity by adding a certain amount of electronically conductive components in the regular concrete matrix. The main purpose of this study is to investigate the electrical and thermal properties of conductive concrete with various graphite contents, specimen dimensions and applied voltages. For this purpose, six different mixtures (the control mixtures and five conductive mixtures with steel fibers of 2% by weight of coarse aggregate and graphite as fine aggregate replacement at the levels of 0%, 5%, 10%, 15% and 20% by weight) were prepared and concrete blocks with two types of dimensions were fabricated. Four test voltage levels, 48 V, 60 V, 110 V, and 220 V, were applied for the electrical and thermal tests. Test results show that the compressive strength of specimens decreases as the amount of graphite increases in concrete. The rising applied voltage decreases electrical resistivity and increases heat of concrete. Meanwhile, higher electrical current and temperature have been obtained in small size specimens than the comparable large size specimens. From the results, it can be concluded that the graphite contents, applied voltage levels, and the specimen dimensions play important roles in electrical and thermal properties of concrete. In addition, the superior electrical and thermal properties have been obtained in the mixture adding 2% steel fibers and 10% graphite.

• Membrane and Water Treatment
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• 제8권1호
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• pp.89-112
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• 2017

Dyeing wastewaters are the most problematic wastewater in textile industries and also, growing amounts of waste fibers in carpet industries have concerned environmental specialists. Among different treatment methods, membrane filtration processes as energy-efficient and compatible way, were utilized for several individual problems. In this research, novel hybrid membranes were prepared by waste fibers of mechanical carpets as useful resource of membrane matrix and industrial graphite powder as filler to eliminate Chrysophenine GX from dyeing wastewater. These membranes were expected to be utilized for first stage of hybrid membrane filtration process including (adsorption-ultrafiltration) and nanofiltration in Kashan Textile Company. For scaling of membrane filtration process, fouling mechanism of these membranes were recognized and explained by the use of genetic algorithm, as well. The graphite increased rejection and diminished permeate flux at low concentration but in high concentration, the performance was significantly worsened. Among all hybrid membranes, 18% wt. waste fibers-1% wt. graphite membrane had the best performance and minimum fouling. The maximum pore size of this optimum membrane was ranged from 16.10 to 18.72 nm.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1995년도 추계학술대회논문집
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• pp.181-187
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• 1995

The effet of glass fiber and graphite on the wear properies in tin-bronze alloy matrix composites was studied by a pin-on-disk type wear testing machine. The results obtained from the wear test were analized by SEM observations of worn surfaces of pins and disks and EPMA composition measurments. The amount of wear was devreased as increasing the content of glass fiber in matrix, since the alloy matrix was reinforced by glass fibers. The wear mechanism of the matrix specimen without glass fibers was proved as the contact area delamination. Oxide layer formed on sliding surface led to the increasing wear resistance. Specimens containing graphite particles showed an lubrication effect to counter disks.

• Transactions on Electrical and Electronic Materials
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• 제16권5호
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• pp.274-279
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• 2015

Reduced graphite oxides (rGOs) were prepared by the common graphite oxidation method and the subsequent reductions. The reduction of graphite oxides (GOs) was conducted chemically and/or thermally. To further reduce the as-prepared rGOs, GOs were treated with chemical/thermal reductions or thermal/chemical reductions, in which the reduction sequence was also considered. The structural changes of as-prepared rGOs, depending on reduction methods, were investigated by X-ray diffraction analyses, Raman spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy. In addition, we discuss the structural change of the rGOs and their closely related physical and electrical properties, such as thermogravimetry, nitrogen adsorption isotherm, and sheet resistance.

• 한국세라믹학회지
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• 제30권9호
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• pp.768-774
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• 1993

Sulphuric acid was intercalated in mesophase pitch based graphite fiber (Thornel P100 of Amoco), PAN based graphite fiber (M40 of Thoray) and PAN based carbon fiber (T300 ofThoray, TZ307 of Taekwang in Korea) by 0.4wt% CrO3/H2SO4 solution. The degree of crystallization of fibers increased P100, M40, TZ307, T300 fiber in order and their d002 values were 3.384, 3.424, 3.470, 3.493$\AA$, respectively. After intercalation P100 fiber formed 1 stage compound whose d002 value was 3.994$\AA$(d001=7.988$\AA$). Other fibers showed (002) reflection belonging to their 1 stage comound and prinstine fiber.

• Composites Research
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• 제20권6호
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• pp.1-7
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• 2007

본 연구에서는 팽창흑연/탄소섬유 혼합 보강 전도성 고분자 복합재료를 2단계 성형 공법으로 제조하였으며, 탄소섬유의 첨가가 전도성 고분자 복합재료의 전기적, 기계적 특성에 미치는 영향을 고찰하였다. 전도성 충진재들은 고분자 수지와 기계적으로 혼합되었으며 이를 통하여 복합재료가 전기적 특성을 가지도록 하였다. 팽창흑연은 입자 간 접촉 면적이 넓기 때문에 복합재료 내 전도성 네트워킹의 형성에 매우 유리하지만, 팽창흑연과 고분자 수지만을 사용하여 상기 공정으로 복합재료를 제조할 경우 우수한 기계적 강도를 얻기가 어렵다. 따라서 이를 보완하기 위하여 탄소섬유를 복합재료에 첨가하였으며 전기적 기계적 물성을 바탕으로 탄소섬유의 혼합 비율을 최적화하였다. 굽힘 강도는 탄소섬유의 충친 비율이 증가할수록 섬유에 의한 강화 효과에 의하여 증가 하지만, 32wt.% 이상에서는 오히려 감소하였다. 이는 여분의 탄소섬유들이 공극을 발생시켜 응력집중이 발생하기 때문으로 판단된다. 전기 전도도는 탄소섬유의 비율이 증가할수록 전도성 공백이 발생하고 팽창흑연의 전도성 네트워킹이 저해되기 때문에 계속 감소한다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 추계학술대회 논문집
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• pp.172-175
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• 2009

A bipolar plate is an important component in a fuel cell in the sense of cost and weight. This study aimed at developing highly conductive, lightweight, and low cost bipolar plates. Hybrid carbons filled poly(phenylene sulfide)(PPS) composite bipolar plates were prepared by using the compression molding technique. Various types and amounts of conducting carbon fillers such as graphite, carbon black, carbon fibers, and carbon nanotubes (CNTs) were adopted for the composites. Electrical conductivity and mechanical properties of the composites were measured in order to investigate effects of each components of fillers. When the graphite is only used as a conducting filler, the electrical conductivity of the composites increases with increasing the content, but the flexural strength decreases dramatically. However, for CNTs and carbon fibers, the flexural strength initially increases and then decreases with increasing the amount of the conducting fillers. The amount of graphite corresponding to the peak of flexural strength was moved to lower content with increasing the amount of CNTs or carbon fiber. When hybrid conducting fillers such as fibrous and particulate fillers were used, the synergy effect in mechanical and electrical properties was observed.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2001년도 제34회 추계학술대회 개최
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• pp.117-126
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• 2001

Tribological properties of high temperature fade were investigated by changing relative amounts of ingredients in the brake friction material. Based on a simple experimental formulation containing 10 ingredients, friction materials were tested using a pad-on-disk type friction tester. Twenty-five friction material specimens with different relative amounts of the ingredients were manufactured according to the constrained mixture design .The difference ($\Delta$${\mu}$=${\mu}$$\sub$max/. -${\mu}$$\sub$min/. ) of friction coefficients was measured to represent the high temperature fade. Results from elevated temperature tests showed that five ingredients including cashew, graphite, Sb$_2$S$_3$, ZrSiO$_4$, and Cu fibers played important roles on $\Delta$${\mu}$. In order to find relative importance on fade phenomena among these ingredients, ANOVA(analysis of variance) was performed in this investigation. Thirty-two friction material specimens by changing ${\pm}$50vol.％ of these five ingredients were tested to examine the relative importance. Results showed that cashew, graphite '||'&'||' Sb$_2$S$_3$, and cashew '||'&'||' graphite aggravated the fade behavior and Cu fibers improved on fade resistance.

• Structural Engineering and Mechanics
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• 제63권5호
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• pp.597-605
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• 2017

Our work aims to analyze using the finite element method the evolution of the stress intensity factor (SIF) parameter K of three laminated folded plates stacks [$+{\alpha}$, $-{\alpha}$], made of the same epoxy matrix and different reinforcement fibers (boron, graphite and glass). Our results show that the angle of orientation of the boron/epoxy composite has no great influence on the variation of the parameter KI. Compared to composite graphite/epoxy and glass/epoxy, the laminated composite boron/epoxy reduces more the SIF KI in the middle of the plate for angles $0^{\circ}{\leq}{\alpha}{\leq}30^{\circ}$.