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

• Advances in materials Research
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• 제6권3호
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• pp.245-255
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• 2017

High energy ball milling is employed to produce iron matrix- multiwall carbon nanotube (MWCNT) reinforced composite. The damage caused to MWCNT due to harsh ball milling condition and its influence on interfacial bonding is studied. Different amount of MWCNT is used to find the optimal percentage of MWCNT for avoidance of the formation of chemical reaction product at the matrix - reinforcement interface. Effect of process control agent is assessed by the use of different materials for the purpose. It is observed that ethanol as a process control agent (PCA) causes degradation of MWCNT reinforcements after milling for two hours whereas solid stearic acid used as process control agent, allows satisfactory conservation of MWCNT structure. It is further noted that at a high MWCNT content (~ 2wt.%), high energy ball milling leads to reaction of iron and carbon and forms iron carbide (cementite) at the iron-MWCNT interface. At low percentage of MWCNT, dissolution of carbon in iron takes place and the amount of reinforcement in iron matrix composite becomes negligibly small. However, under the present ball milling condition (ball to metal ratio~ 6:1 and 200 rpm vial speed) iron-1wt.% MWCNT composite of good interfacial bonding can retain the tubular structure of reinforcing MWCNT.

• 한국진공학회지
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• 제17권5호
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• pp.473-480
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• 2008

화학기상증착법과 Ni 나노입자 배열을 이용한 탄소나노튜브의 최적 성장 조건을 연구했다. Ni 입자의 크기를 변화시키는 방법으로 탄소나노튜브의 직경을 20 nm 이하까지 제어할 수 있었다. 개별 Ni 입자의 크기와 위치는 기존의 식각법 등을 이용하여 웨이퍼 수준의 대면적에서 연속적으로 제어가 가능하였다. 성장온도, 탄소원, 희석가스 등의 비율을 최적화 함으로써 $SiO_2/Si$ 웨이퍼의 넓은 면적에서 각 Ni 입자로부터 단 한 개씩의 탄소나노튜브가 100% 확률로 성장 가능하다는 것을 보였다. 탄소나노튜브의 위치, 직경, 벽두께 등의 특성들은 성장조건을 조정하여 제어가능하다는 것을 보였다.

• 한국진공학회지
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• 제17권4호
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• pp.365-373
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• 2008

최적화된 량의 황화수소 첨가 가스를 이용하여 실리콘 기판위에 증착된 Fe/Al 박막위에 촉매 화학 기상 증착법을 사용하여 직경이 얇은 다중층 탄소나노튜브가 수직 정렬되어 합성되었다. 주사전자현미경 관측 이미지에서 합성된 탄소나노튜브는 상대적으로 일정한 길이를 가지고 기판에 수직으로 정렬되었다. 투과전자현미경 관측에서 합성된 탄소나노튜브는 10nm 이내의 작은 외경을 가졌고 촉매가 거의 없었다. 평균 튜브의 벽 수는 약 다섯 개이다. 수직 정렬된 직경이 얇은 다중층 탄소나노튜브의 성장 메카니즘이 제시되었다. 수직 정렬된 직경이 얇은 다중층 탄소나노튜브는 $0.1\;{\mu}A/cm^2$의 전류밀도에서 약 $1.1\;V/{\mu}m$ 낮은 턴-온 전계를 나타내었고 $2.7\;V/{\mu}m$의 전계에서 약 $2.5\;mA/cm^2$의 전류밀도를 얻었다. 게다가, 수직 정렬된 직경이 얇은 다중층 탄소나노튜브는 약 $1\;mA/cm^2$의 전류밀도에서 20시간동안 전류밀도 저하 없이 좋은 전계 방출 안정성을 보여주었다.

• 상하수도학회지
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• 제34권2호
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• pp.127-137
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• 2020

In this study, a MWCNT(multi-wall carbon nanotube) was added to polysulfone(PSf) support layer to improve flux of TFC(thin film composite) RO(reverse osmosis) membrane. Two different kinds of MWCNT were used. Surfaces of some MWCNTs were modified hydrophilically through acid treatment, while those of other MWCNTs were modified through heat treatment to maintain their hydrophobicity. MWCNT/PSf support layer was prepared by adding PSf to the NMP mixed solvent containing 0.1 wt% MWCNTs using a phase inversion method. The surface porosity of the MWCNT/PSf support increased by 42~46% while its surface pore size being maintained. The TFC RO membrane made of MWCNT/PSf support layer showed a 20% flux increase while its salt rejection characteristics is sustained. In addition, the MWCNT/PSf support layer has better mechanical stability than the PSf support layer, there resulting in an increased resistance of flux reduction due to physical pressure.

• 한국분말재료학회지
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• 제21권5호
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• pp.343-348
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• 2014

A powder-in-sheath rolling (PSR) process utilizing a copper alloy tube was applied to a fabrication of a multi-walled carbon nanotube (CNT) reinforced aluminum matrix composite. A copper tube with an outer diameter of 30 mm and a wall thickness of 2 mm was used as a sheath material. A mixture of pure aluminum powders and CNTs with the volume contents of 1, 3, 5 vol% was filled in the tube by tap filling and then processed to 93.3% height reduction by a rolling mill. The relative density of the CNT/Al composite fabricated by the PSR decreased slightly with increasing of CNTs content, but showed high value more than 98%. The average hardness of the 5%CNT/Al composite increased more than 3 times, compared to that of unreinforced pure Al powder compaction. The hardness of the CNT/Al composites was some higher than that of the composites fabricated by PSR using SUS304 tube. Therefore, it is concluded that the type of tube affects largely on the mechanical properties of the CNT/Al composites in the PSR process.

• 한국재료학회지
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• 제30권3호
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• pp.149-154
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• 2020

A powder-in-sheath rolling method is applied to the fabrication of a carbon nano tube (CNT) reinforced copper composite. A copper tube with outer diameter of 30 mm and wall thickness of 2 mm is used as sheath material. A mixture of pure copper powder and CNTs with a volume content of 3 % is filled in a tube by tap filling and then processed to an 93.3 % reduction using multi-pass rolling after heating for 0.5 h at 400 ℃. The specimen is then sintered for 1h at 500 ℃. The relative density of the 3 vol%CNT/Cu composite fabricated using powder in sheath rolling is 98 %, while that of the Cu powder compact is 99 %. The microstructure is somewhat heterogeneous in width direction in the composite, but is relatively homogeneous in the Cu powder compact. The hardness distribution is also ununiform in the width direction for the composite. The average hardness of the composites is higher by 8Hv than that of Cu powder compact. The tensile strength of the composite is 280 MPa, which is 20 MPa higher than that of the Cu powder compact. It is concluded that the powder in sheath rolling method is an effective process for fabrication of sound CNT reinforced Cu matrix composites.

• 한국표면공학회지
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• 제54권4호
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• pp.194-199
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• 2021

In this study, rebar corrosion detection sensor was fabricated using multi-walled carbon nanotubes (MWCNTs). MWCNTs were pre-treated in the acid electrolytes to attach the carboxylic acid to the surface of MWCNTs. The fabricated sensor was attached on the surface of rebar and it detected the corrosion of steel using LCR meter with variation of capacitance. The surface morphology and electrical properties were characterized using scanning electron microscope (SEM) and electrical test equipment, respectively. To verify the corrosion detection characteristics, comparison experiment using plastic bar was performed. Moreover, mechanism of corrosion detection sensor was discussed.

• 한국분말재료학회지
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• 제21권1호
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• pp.50-54
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• 2014

A powder-in-sheath rolling method was applied to a fabrication of a carbon nano tube (CNT) reinforced aluminum composite. A STS304 tube with an outer diameter of 34 mm and a wall thickness of 2 mm was used as a sheath material. A mixture of pure aluminum powders and CNTs with the volume contents of 1, 3, 5 vol was filled in the tube by tap filling and then processed to 73.5% height reduction by a rolling mill. The relative density of the CNT/Al composite fabricated by the powder-in-sheath rolling decreased slightly with increasing of CNTs content, but exhibited high value more than 98. The grain size of the aluminum matrix was largely decreased with addition of CNTs; it decreased from $24{\mu}m$ to $0.9{\mu}m$ by the addition of only 1 volCNT. The average hardness of the composites increased by approximately 3 times with the addition of CNTs, comparing to that of unreinforced pure aluminum. It is concluded that the powder-in-sheath rolling method is an effective process for fabrication of CNT reinforced Al matrix composites.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2171-2176
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• 2007

The 3-omega (3-${\omega}$) method is utilized to measure the thermal conductivity of nanofluids. A metal line heater on a silicon nitride membrane bridge structure is microfabricated by a bulk silicon etching method. Localized measurement of the thermal conductivity within the nanofluids droplet is possible by the fabricated 3-${\omega}$ sensor. Time varying AC temperature amplitudes and thermal conductivities are measured to check the stability of the nanofluids containing multi-wall carbon nanotubes (MWCNTs). Stabilities of MWCNT nanofluids prepared with different chemical treatments are compared. Acid treated MWCNT showed best dispersion stability in water while MWCNTs dispersed in water with surfactants such as Gum Arabic and Sodium dodecyl benzene sulfate showed clear sign of gravity dependence.