• 제목, 요약, 키워드: Chemical vapor infiltration

검색결과 36건 처리시간 0.032초

Mechanical Properties of Cf/SiC Composite Using a Combined Process of Chemical Vapor Infiltration and Precursor Infiltration Pyrolysis

  • Kim, Kyung-Mi;Hahn, Yoonsoo;Lee, Sung-Min;Choi, Kyoon;Lee, Jong-Heun
    • 한국세라믹학회지
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    • v.55 no.4
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    • pp.392-399
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    • 2018
  • $C_f/SiC$ composites were prepared via a process combining chemical vapor infiltration (CVI) and precursor infiltration pyrolysis (PIP), wherein silicon carbide matrices were infiltrated into 2.5D carbon preforms. The obtained composites exhibited porosities of 20 vol % and achieved strengths of 244 MPa in air at room temperature and 423 MPa at $1300^{\circ}C$ under an Ar atmosphere. Carbon fiber pull-out was rarely observed in the fractured surfaces, although intermediate layers of pyrolytic carbon of 150 nm thickness were deposited between the fiber and matrix. Fatigue fracture was observed after 1380 cycles under 45 MPa stress at $1000^{\circ}C$. The fractured samples were analyzed by transmission electron microscopy to observe the distributed phases.

펄스화학기상침트법에 의한 탄소/탄소 복합재료의 치밀화에 있어서 가스유지시간 유무의 영향 (Densification of Carbon/Carbon Composites by Pulse CVI with and without Residence)

  • 이용근;류호진;박희동
    • 한국세라믹학회지
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    • v.33 no.8
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    • pp.935-941
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    • 1996
  • Two-dimensional carbon/carbon preforms made of PAN-based carbon yarn and phenolic resin were densified with pyrolysis of propane by pulse chemical vapor infiltration where repeated the cycle of gas introduction residence and evacuation. Maximim density increment was 14% when infiltration temperature and time were 100$0^{\circ}C$ and 21.25 hrs respectively. The distribution of deposits of pyrocarbon by this process has been occurred uniformly in the bottom middle and top of carbon/carbon composite preform Pulse CVI with residence is most effective in increasing density and shortening infiltration time among isothermal CVI and pulse CVI with and without residence.

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메틸삼염화규소로부터 탄화규소 침착의 Pulse-CVI에 대한 수치모사 연구 (Studies on the Mathematical Modelling of the Pulse-CVI for the Infiltration of Siliconcarbide from Methyltrichlorosilane)

  • 김인구;김민기;정귀영
    • Composites Research
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    • v.18 no.5
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    • pp.27-33
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    • 2005
  • 본 연구에서는 펄스-CVI (Chemical Vapor Infiltration)에 의해 탄화규소/탄소 복합재료를 제조하는 공정에 대한 수치모사가 행해졌다. 각 펄스가 가스 주입시간, 반응시간, 배출시간으로 구성될 때, 반응시간과 배출시간의 영향이 관찰되었다. 또한 반응가스 농도와 압력의 영향이 연구되었다. 탄소프리폼에의 탄화규소의 균일한 침착과 반응시간 단축을 위한 펄스-CVI공정의 이점이 확인되었다.

화학기상침착법에 의한 SiCf/SiC 복합체의 제조 (Fabrication of SiCf/SiC Composite by Chemical Vapor Infiltration)

  • 박지연;김대종;김원주
    • Composites Research
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    • v.30 no.2
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    • pp.108-115
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    • 2017
  • $SiC_f/SiC$ 복합체를 제조하는 공정들 중에서 화학기상 침착(Chemical Vapor Infiltration) 공정은 저온에서 실형상이나 복잡한 형상을 제조할 수 있고, 기지상의 미세구조를 제어할 수 있으며, 고순도를 지닌 $SiC_f/SiC$ 복합체를 제조할 수 있는 효과적인 방법이다. 그러나 잔유 기공을 가지며 공정시간이 긴 단점이 있다. 기공률을 줄이고 효과적인 기지상 채움을 위하여 휘스커(whisker) 성장과 기지상 채움공정을 연속하여 수행하는 whisker growing assisted 화학기상침착공정이 개발되었다. 기지상 채움 전에 프리폼에 SiC 휘스커를 미리 성장시키면 섬유간이나 번들간에 존재하는 큰 기공을 작게 분할하여 기지상 채움 효율을 증진할 수 있다. 본 논문에서는 $SiC_f/SiC$ 복합체 제조를 위한 화학기상침착법공정의 기초와 일반적인 화학기상침착공정과 whisker growing assisted 화학기상침착공정으로 제조한 $SiC_f/SiC$ 복합체의 실험결과들을 간략히 서술하였다.

Numerical study on heat transfer and densification for SiC composites during thermal gradient chemical vapour infiltration process

  • Ramadan, Zaher;Im, Ik-Tae
    • Carbon letters
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    • v.25
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    • pp.25-32
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    • 2018
  • In this study, a thermal-gradient chemical vapor infiltration (TG-CVI) process was numerically studied in order to enhance the deposition uniformity within the preform. The computational fluid dynamics technique was used to solve the governing equations for heat transfer and gas flow during the TG-CVI process for two- and three-dimensional (2-D and 3-D) models. The temperature profiles in the 2-D and 3-D models showed good agreement with each other and with the experimental results. The densification process was investigated in a 2-D axisymmetric model. Computation results showed the distribution of the SiC deposition rate within the preform. The results also showed that using two-zone heater gave better deposition uniformity.

High textured carbon from chemical vapor infiltration with ethanol precursor and its rate of pyrolytic carbon deposition

  • Choi, Si Won;Joo, Kyung Do;Chung, Gui-Yung
    • The Korean Journal of Chemical Engineering
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    • v.34 no.10
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    • pp.2764-2772
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    • 2017
  • Preparation of C/C composites with ethanol precursor was studied and the role of ethanol in obtaining high textured (HT) carbon was confirmed. HT carbon was obtained more with ethanol precursor than with propane precursor as reported by Ren et al. The pyrolytic carbon deposition rate constant from ethanol precursor, which has never been reported before in any other research, was obtained. It was confirmed that a proper mixture precursor of ethanol and propane could be used in the process of temperature gradient chemical vapor infiltration (TG-CVI) on behalf of the uniform deposition throughout the preform and the deposition with more HT carbon,. The pyrolytic carbon deposition rate constant for the CVI with propane precursor obtained in this research was 2.2-times greater than that reported by Vaidyaraman.

다단계 화학반응과 밀도화 모델을 이용한 탄소/탄소 복합재 화학기상침투 공정의 확산 및 유동 수치해석 (Numerical Simulation of Diffusion and Flow in Fabrication of Carbon/Carbon Composite Using Chemical Vapor Infiltration)

  • 김혜규;지우석;조남춘;박종규
    • Composites Research
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    • v.32 no.1
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    • pp.56-64
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    • 2019
  • 본 연구에서는 탄화수소를 이용한 탄소/탄소 복합재의 화학기상침투 공정에 대해 프리폼의 밀도 변화, 공극률 변화와 다단계 화학반응을 고려한 수치해석 모델을 개발하였다. 프리폼을 다공성 매질로 가정하여 공극률에 따른 확산 및 유동 특성의 변화를 도입하였다. 검증을 위하여 프리폼 내부 유동이 0으로 제약된 경우와 유동해석을 통해 계산된 경우에 대해 수치해석을 수행하였으며, 해석 결과가 문헌의 실험치와 일치하는 것을 보였다.

SiC 복합체 제조를 위한 화학기상침착공정에 대한 수치해석 연구 (Numerical Study on CVI Process for SiC-Matrix Composite Formation)

  • 배성우;임동원;임익태
    • 반도체디스플레이기술학회지
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    • v.14 no.2
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    • pp.61-65
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    • 2015
  • SiC composite materials are usually used to very high temperature condition such as thermal protection system materials at space vehicles, combustion chambers or engine nozzles because they have high specific strength and good thermal properties at high temperature. One of the most widely used fabrication methods of SiC composites is the chemical vapor infiltration (CVI) process. During the process, chemical gases including Si are introduced into porous preform which is made by carbon fibers for infiltration. Since the processes take a very long time, it is important to reduce the process time in designing the reactors and processes. In this study, both the gas flow and heat transfer in the reactors during the processes are analyzed using a computational fluid dynamics method in order to design reactors and processes for uniform, high quality SiC composites. Effects of flow rate and heater temperature as process parameters to the infiltration process were examined.

Infiltration 공정으로 제조한 Nicalon 섬유강화 SiC 복합재료 (Nicalon-Fiber-Reinfored SiC Composites Via Infiltration)

  • 김민수;김영욱;한경섭;박정현
    • 한국세라믹학회지
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    • v.30 no.12
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    • pp.993-998
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    • 1993
  • Nicalon-fiber-reinforced SiC composites were fabricated via polymer solution infiltration/chemical vapor infiltration (PSI/CVI) and CVI. Specifically, data were taken and compared for flexural strength, fracture toughness, and processing time. The two process resulted in comparable mechanical properties, and PSI/CVI process resulted in significantly reduced infiltration time.

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등온 저압화학기상침투법에 의한 탄소/탄소 복합재료의 치밀화에 대한 제조공정변수의 영향 (Effect of Processing Parameters on the Densification of Carbon/Carbon Composite by Isothermal Low-Pressure Chemical Vapor Infiltration)

  • 박희동;안치원;조건;윤병일;김광수
    • 한국재료학회지
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    • v.4 no.3
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    • pp.259-267
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    • 1994
  • 프로판($C_3H_8$)을 반응가스로 사용하여 등온 저압화학기상침투법(low-pressure chemical vapor infiltration)으로 탄소/탄소 복합재료를 치밀화 할 때 반응온도, 반응가스농도, 가스유량, 반응압력 등의 제조공정변수들이 치밀화에 미치는 영향을 알아보기 위하여 실험계획법(Rdbust design method)에 의한 실험을 행하였다. 1회의 등온 저압화학기상침투 실험으로 탄소/탄소 복합재료의 부피 밀도와 표면과 내부의 부피 밀도의 차이를 특성치(characteristic value)로 한 실험계획법의 분산분석(analysis of variance)에 의하면 반응온도, 반응가스농도, 가스유량 등의 제고공정변수가 치밀화에 기여도가 높으며, 반응압력의 기여도와 제조공정변수들의 교호작용(interaction)에 의한 기여도는 낮은 것으로 나타났다. 반응온도가 $1100^{\circ}C$, 반응가스농도가 100% $C_3H_8$, 가스유량이 100 SCCM, 반응압력이 5torr인 조건에서 탄소/탄소 복합재료는 가장 높은 부피 밀도값을 나타내었으나 시편의 표면과 내부의 부피 밀도 차이값은 컸다.

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