• 한국분말재료학회지
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• 제15권1호
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• pp.58-62
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• 2008

Reaction bonded silicon carbide (RBSiC) is an important engineering ceramic because of its high strength and stability at elevated temperatures, and it is currently fabricated using reasonably cheap manufacturing processes, some of which have been used since the 1960s. However, forming complicated shapes from these materials is difficult because of their poor workability. The purpose of this work is to join the reaction-bonded SiC parts using a preceramic polymer as joint material. The manufacturing of ceramic material in the system Si-O-C from preceramic silicon containing polymers such as polysiloxanes has attained particular interest. The mixtures of preceramic polymer and filler materials, such as SiC, Si and MoSi, were used as a paste for the joining of reaction sintered SiC parts. The joining process during the annealing in Ar atmosphere at $1450^{\circ}C$ were described. The maximum strength of the joints was 63 MPa for the specimen joined with 10 vol.% of $MoSi_2$ and 30 vol.% of SiC as filler materials. Fracture occurred in the joining layer. This indicates that the joining strength is limited by the strength of the joint materials.

• 공업화학
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• 제4권4호
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• pp.639-652
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• 1993

• 한국세라믹학회지
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• 제44권11호
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• pp.622-626
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• 2007

Graphite is widely used in electronic industry due to its excellent electrical and thermal properties. However, graphite starts to oxidize around $400^{\circ}C$ that seriously degrades its properties. SiC coating can be applied to graphite foam to improve its high temperature oxidation resistance. In this research, SiC coating on graphite foam was made via preceramic polymer using a polyphenylcarbosilane. 20% of polyphenylcarbosilane in hexane solution was coated onto graphite by dip coating method. Thermal oxidation was carried out at $200^{\circ}C$ for crosslink of the preceramic polymer and the sample were pyrolysized at $800^{\circ}C{\sim}1200^{\circ}C$ under nitrogen to convert the preceramic polymer to SiC film. The microstructure of the SiC coating after pyrolysis was investigated using FESEM and oxidation resistance up to $800^{\circ}C$ was evaluated.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 1993년도 ACT 93
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• pp.227-231
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• 1993

• 한국재료학회:학술대회논문집
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• 한국재료학회 2009년도 추계학술발표대회
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• pp.34.2-34.2
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• 2009

The ceramic coatings on metallic materials have attracted by many researchers due to the chemical inertness of ceramic materials. In such aspect, SiOC is a promising material tobe used as protective coating layer on metallic materials due to its outstanding thermal stability and chemical inertness. In this research, SiOC coating was carried out onto SuS-316 substrate using Cl free preceramic polymers such aspolyphenylcarbosilane. 20% of polymethylphenylsilane in cyclohexane solution was coated onto metal surface by dip coating method. Thermal oxidation was carried out at $200^{\circ}C$ for crosslink of the preceramic polymer and the sample was pyrolysized at $800^{\circ}C$ under argon to convert the preceramic polymer to amorphous SiOCx state. The microstructure of the SiOCx film after pyrolysis was investigated using FE-SEM. Corrosion resistance of SiOC coated SuS-316 substrate has been investigated using 5% HCl solution at 25, 40, 60 and $80^{\circ}C$ for 7days. The data revealed that the corrosion resistance increased with SiOC coating on SuS-316 substrate.

• 한국세라믹학회지
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• 제44권5호
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• pp.184-189
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• 2007

In this study, a novel-processing route for producing microcellular cordierite ceramics has been developed. The proposed strategy for making the microcellular cordierite ceramics involves three steps: (i) fabricating ceramic-filled preceramic foams by heating a mixture of polysiloxane, expandable microspheres, talc, and alumina in a mold, (ii) cross-linking the foamed body, and (iii) transforming the body into microcellular cordierite ceramics by sintering. Cu jig was used for near net shaping in the foaming step. The experimental variables such as the shape of foaming jig and the content of expendable microsphere were investigated. By controlling the content of expendable microsphere, it was possible to make the porous cordierite ceramics with cell density of ${\sim}1.0{\times}10^9\;cells/cm^3$.

• 한국세라믹학회지
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• 제48권6호
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• pp.499-503
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• 2011

Recently, variety of organic and inorganic hybrid materials have recently investigated as alternative routes to SiOC, $SiO_2$ thin film formation at low temperatures for applications in electronic ceramics. Specially, silicon based polymers, such as polycarbosilane, polysilane and polysilazane derivatives have been studied for use in electronic ceramics and have been applied as dielectric or insulating materials. In this study, Polycarbosilane(PCS), which Si-$CH_2$-Si bonds build up the backbone of the polymer, has been investigated as low-k materials using a solution process. After heat treatment at 350$^{\circ}C$ under $N_2$ atmosphere, chemical composition and dielectric constant of the thin film were $SiO_{0.27}C_{1.94}$ and 1.2, respectively. Mechanical property measured using nanoindentor shows 1.37 GPa.

• 한국세라믹학회지
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• 제49권4호
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• pp.279-286
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• 2012

Microstructure tailoring of filler loaded preceramic polymer systems offers a high potential for property improvement of Si-based ceramics and composites. Advancements in manufacturing of bulk materials by controlling microstructure evolution during thermal induced polymer-ceramic transforma-tion and polymer-filler reactions will be presented. Rate controlled pyrolysis, multilayer gradient laminate design and surface modification by gas solid reaction are demonstrated to yield ceramic components of high fractional density and superior mechanical properties. Emerging fields of applications are presented.

• 한국재료학회지
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• 제24권9호
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• pp.474-480
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• 2014

Process conditions for the impregnation of polycarbosilane preceramic polymer into SiC-based composites were investigated. Two kinds of preceramic polymer (PCP) was impregnated into SiC-fiber fabrics with different solvents of n-hexane and divinylbenzene (DVB). Both microstructural observations and mechanical tests were conducted to evaluate the impregnation. The matrix phases were particulated in the case of hexane solvents. Apparent relative density of the matrix was about 78.8%. The density of matrix was increased to about 96.1-98.8% when the DVB was used; however, brittle fracture was observed during a bending test. The modulus of toughness was less than $0.74J/m^3$. The fabric impregnated with a mixed PCP-dissolved solution showed intermediate characteristics with relative high density of filling (apparent density of ~96.1%) as well as proper bending behavior. The modulus of toughness was increased to about $5.31J/m^3$. The composites developed by changing the precursor and solvent suggested the possibility of fabricating SiCf/SiC composites without a fiber to matrix interphase coating.

• Composites Research
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• 제30권2호
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• pp.102-107
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• 2017

프리세라믹폴리머는 기존의 세라믹 공정으로는 얻을 수 없는 다양하고 복잡한 구조의 세라믹 소재를 구현할 수 있다. 대표적인 프리세라믹폴리머인 폴리카보실란은 분자구조 제어를 통해 실리콘과 탄소의 함량비 조절이나 분자구조의 선형성을 향상시키고 분자량 및 분자량분포 제어를 통해 탄화규소섬유를 포함한 다앙한 형상/미세구조의 탄화규소 세라믹을 제조할 수 있다. 본 논문에서는 폴리카보실란의 합성 및 분자구조제어기술과 이를 용융방사 및 안정화, 열처리를 거쳐 제조되는 탄화규소섬유섬유, 그리고 PIP 공정으로 만들어지는 세라믹섬유복합소재 기술에 대하여 논하였다. 더불어 나노다공구조를 갖는 탄화규소 중공사와 같이 폴리카보실란을 이용해 구현할 수 있는 복잡구조의 탄화규소 소재 개발 예를 소개하였다.