Effect of Compositional Parameters on the Characteristics of C-SiC-$B_4C$ Composites

Aggarwal, R.K.,Bhatia, G.B.,Saha, M.,Mishra, A. Korean Carbon Society 2004 Carbon Letters Vol.5 No.4

Carbon-ceramic composites refer to a special class of carbon based materials which cover the main drawbacks of carbon, particularly its proneness to air oxidation, while essentially retaining its outstanding properties. In the present paper, the authors report the results of a systematic study made towards the development of C-SiC-$B_4C$ composites, which involves the effects of compositional parameters, namely, carbon-to-ceramic and ceramic-to-ceramic ratios, on the oxidation behaviour as well as other characteristics of these composites. The C-SiC-$B_4C$ composites, heat-treated to $1400^{\circ}C$, have shown that their oxidation behaviour at temperatures of 800~$1200^{\circ}C$ depends jointly on the total ceramic content and the SiC : $B_4C$ ratio. Good compositions of C-SiC-$B_4C$ composites exhibiting zero weight loss in air at temperatures of 800~$1200^{\circ}C$ for periods of 4~9 h, have been identified. Composites with these compositions undergo a weight gain or a maximum weight loss of less than 3% during the establishment of a protective layer at the surface of carbon in a period of 1~6 h. Significant improvement in the strength of C-SiC-$B_4C$ composites has been observed which increases with an increase in the total ceramic content and also with an increase in the SiC : $B_4C$ ratio.

New application of layered silicates for carbon fiber reinforced carbon composites

Jeong, E.,Kim, J.,Cho, S.H.,Kim, J.i.,Han, I.S.,Lee, Y.S. Korean Society of Industrial and Engineering Chemi 2011 Journal of industrial and engineering chemistry Vol.17 No.2

To investigate potential use of a layered silicate, illite, for carbon fiber-reinforced (C/C) composites, the C/C composites were prepared at different carbonization temperatures, specifically 1000<SUP>o</SUP>C and 1650<SUP>o</SUP>C using illite. The physical and chemical changes in the prepared C/C composites that were induced by the addition of illite and anti-oxidation and mechanical properties of the composites were investigated. A carbothermal reaction occurred due to the addition of illite when the composite was prepared at 1650<SUP>o</SUP>C, which resulted in the formation of SiC from the illite and carbon. The physical structures of the composites changed due to the increased interfacial adhesion between the reinforcing carbon fibers and the carbon matrix, which resulted increased bulk densities, and decreased porosities. The carbothermal reaction and physical structural changes that were induced by the addition of illite synergistically improved the anti-oxidation properties of the prepared composites, which were observed as a delay in oxidation. In addition, illite filler also improved flexural strength of the composite, due to the increased interfacial adhesion induced by illite addition. Therefore, the application of the layered silicate, illite, for C/C composites can be quite promising.

Oxidation behavior of C/C composites with B4C-SiCZrC-ZrB2 coating prepared by infiltration and pyrolysis

Xiao-Hua Zuo,Zhi-Jun Dong,Guan-Ming Yuan,Zheng-Wei Cui,Xuan-Ke Li 한양대학교 세라믹연구소 2021 Journal of Ceramic Processing Research Vol.22 No.1

Polycarbosilane, B-Si and B-Si-Zr modification coal tar pitch were used as impregnate agent for infiltration and pyrolysis formation of carbon/carbon (abbreviated as C/C) composites with B4C-SiC-ZrC-ZrB2 coating. The density of the composites was examined to be 1.0 g·cm-3, 1.4 g·cm-3 and 1.8 g·cm-3, respectively. The phase compositions, surface morphologies and element distributions of the coating were analyzed by X-ray diffraction (XRD) scanning electron microscopy (SEM) and energy dispervive spectroscopy (EDS), respectively. The result showed that the two composites with a density of 1.4 g·cm-3 and 1.8 g·cm-3 displayed compact microstructures. The oxidation behavior of the composites was studied by oxidation in air at temperatures from 800 to 1,550 ℃ for 1 h. The composites with a density of 1.8 g·cm-3 exhibited a lower weight loss of 1.8 % after oxidation. B4C-SiC-ZrC-ZrB2 coating was found to provide the best protection by the precipitated B2O3, SiO2 and ZrO2 on the surface of the composites during the oxidation process, which were characterized by self-healing and antioxidation. The C/C composites with B4C-SiC-ZrC-ZrB2 coating performed well at high temperatures with the formation of complex oxides glass film that prevented oxygen from further spreading into the matrix.

Preparation of oxidation-protective SiC coatings for C/SiC composites by pulsed chemical vapor deposition

Shaoming Dong,Haiming Wen,Qing Zhou,Yusheng Ding 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.3

Single-layer SiC coatings and multilayer (C/SiC)n coatings for oxidation protection of C/SiC composites were prepared by a pulsed chemical vapor deposition (pulsed CVD) method, a modification of pulsed chemical vapor infiltration (pulsed CVI). Pulsed CVD enabled the original pores in the substrates to be filled by the coatings, which contributed to improved adhesion between the coatings and the substrates. No deposition defects were observed in the dense SiC coatings. Multilayer (C/SiC)n coatings could dissipate thermal stresses in the coatings, which reduced the number and width of micro-cracks in the coatings and accordingly improved the oxidation-protection capability of the coatings. Oxidation tests in dry air showed that the oxidation resistance of the coated composites was significantly improved compared with that of the uncoated ones. Single-layer SiC coatings and multilayer (C/SiC)n coatings for oxidation protection of C/SiC composites were prepared by a pulsed chemical vapor deposition (pulsed CVD) method, a modification of pulsed chemical vapor infiltration (pulsed CVI). Pulsed CVD enabled the original pores in the substrates to be filled by the coatings, which contributed to improved adhesion between the coatings and the substrates. No deposition defects were observed in the dense SiC coatings. Multilayer (C/SiC)n coatings could dissipate thermal stresses in the coatings, which reduced the number and width of micro-cracks in the coatings and accordingly improved the oxidation-protection capability of the coatings. Oxidation tests in dry air showed that the oxidation resistance of the coated composites was significantly improved compared with that of the uncoated ones.

탄화붕소-탄화규소 복합체의 미세구조와 기계적 특성

소성민,김경훈,박주석,김민숙,김형순,So, Sung Min,Kim, Kyoung Hun,Park, Joo Seok,Kim, Min Suk,Kim, Hyung Sun 한국결정성장학회 2019 한국결정성장학회지 Vol.29 No.6

B₄C-SiC 복합체를 소결 첨가제 없이 일축가압소결법을 통해 제조하였으며 소결체의 결정상, 상대밀도, 미세구조 및 기계적 특성을 평가하였다. 제조된 B₄C-SiC 복합체에서 B₄C와 SiC는 균일하게 분산되어 결정립 성장을 억제하고 세밀하고 균일한 미세구조를 형성하였으며 이를 통해 B₄C-SiC 복합체의 기계적 특성을 향상시킬 수 있었다. 소결온도 2,000℃, 40 MPa 압력 조건에서 소결된 B₄C-SiC 복합체의 상대밀도는 99.8 % 이상이었으며, B₄C 50 wt% 조성 복합체의 꺾임 강도와 비커스 경도는 각각 약 625 MPa과 30 GPa로 측정되었다. B₄C-SiC composites were fabricated using hot press sintering method without sintering additives at 1,900~2,000℃ under a pressure of 40 MPa. The crystal phase, relative density, microstructure, and mechanical properties of B₄C-SiC composites were evaluated. When B₄C and SiC were uniformly dispersed in the composite, grain growth was inhibited, and a sintered body with a fine and uniform microstructure, with improved mechanical properties, was fabricated. The relative density of B₄C-SiC composites sintered under 2,000℃ of temperature and 40 MPa of pressure was over 99.8 %, and the bending strength and Vicker's hardness at 50 wt% of B₄C were 645 MPa and 30.6 GPa, respectively.

C/C-SiC 복합재 제동 디스크의 열특성 유한요소 해석

나인균(In-Kyun Na),구병춘(Byeong-Choon Goo) 한국철도학회 2013 한국철도학회 학술발표대회논문집 Vol.2013 No.5

철도차량의 경량화 및 성능향상을 위해 첨단소재에 대한 연구와 적용이 확대되고 있다. 철도기술 선진국에서 연구되고 있는 첨단소재는 AL 복합재, 세라믹, C/C 복합재, 등이 있으며, 상용화를 위해 연구가 계속되고 있다. 본 연구에서는 유한 요소 해석을 통해 C/C-SiC 복합재의 철도차량용 제동 디스크에 대한 열특성 평가방법을 제시하고 평가하였다. 해석 철차는 UIC code 541-3의 140km/h급 차량에 적용된 정지제동 조건을 참조하였고, 마찰계수는 0.35를 적용하였다. 제동 중 발생한 열에너지는 마찰 표면에 집중되었고, 열응력은 제동 초속도의 크기가 증가 할수록 커지는 경향을 보였다. The application of the advanced material research is escalated for performance enhancement and weight-reduction of railway. The advanced material such as Al composites, Ceramics, C/C composites, etc. is studied from developed countries and conducted to carry out the research to commercialize the railway technology. In present study, we estimated thermal characteristics of C/C-SiC composite brake disc for railroad vehicles. Analyses were carried out by ABAQUS, which were followed up by UIC code 541-3. The braking condition is stopping brake with V=140km/h. The friction coefficient of 0.35 was applied. The occurred heat energy was mainly concentrated on friction surfaces during the braking.

New application of layered silicates for carbon fiber reinforced carbon composites

정의경,이영석,Jinhoon Kim,Se Ho Cho,Jeong-il Kim,In-Sub Han 한국공업화학회 2011 Journal of Industrial and Engineering Chemistry Vol.17 No.2

To investigate potential use of a layered silicate, illite, for carbon fiber-reinforced (C/C) composites, the C/C composites were prepared at different carbonization temperatures, specifically 1000 8C and 1650 8C using illite. The physical and chemical changes in the prepared C/C composites that were induced by the addition of illite and anti-oxidation and mechanical properties of the composites were investigated. A carbothermal reaction occurred due to the addition of illite when the composite was prepared at 1650 8C,which resulted in the formation of SiC from the illite and carbon. The physical structures of the composites changed due to the increased interfacial adhesion between the reinforcing carbon fibers and the carbon matrix, which resulted increased bulk densities, and decreased porosities. The carbothermal reaction and physical structural changes that were induced by the addition of illite synergistically improved the anti-oxidation properties of the prepared composites, which were observed as a delay in oxidation. In addition, illite filler also improved flexural strength of the composite, due to the increased interfacial adhesion induced by illite addition. Therefore, the application of the layered silicate, illite, for C/C composites can be quite promising.

Application and evaluation of boron nitride-assisted liquid silicon infiltration for preparing Cf/SiC composites

Jin-Hoon Kim,Eui-Gyung Jeong,Se-Young Kim,Young-Seak Lee 한국탄소학회 2011 Carbon Letters Vol.12 No.2

C/SiC composites were prepared by boron nitride (BN)-assisted liquid silicon infiltration (LSI), and their anti-oxidation and mechanical properties were investigated. The microstructures, bulk densities, and porosities of the C/SiC composites demonstrated that the infiltration of liquid silicon into the composites improved them, because the layered-structure BN worked as a lubricant. Increasing the amount of BN improved the anti-oxidation of the prepared C/SiC composites. This synergistic effect was induced by the assistance of BN in the LSI. More thermally stable SiC was formed in the composite, and fewer pores were formed in the composite, which reduced inward oxygen diffusion. The mechanical strength of the composite increased up to the addition of 3% BN and decreased thereafter due to increased brittleness from the presence of more SiC in the composite. Based on the anti-oxidation and mechanical properties of the prepared composites, we concluded that improved anti-oxidation of C/SiC composites can be achieved through BN-assisted LSI, although there may be some degradation of the mechanical properties. The desired anti-oxidation and mechanical properties of the composite can be achieved by optimizing the BN-assisted LSI conditions.

Effects of different carbon sources on the phase composition and microstructure of synthesized SiC-B4C composite powders

Yu Cao,Ruyi Deng,Jilin Hu,Jinxiu He,Dapeng Lei,Zhanjun Chen,Yangxi Peng 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.2

SiC-B4C composite powders were synthesized by the carbothermal reduction method under an argon atmosphere usingdifferent kinds of carbon sources (carbon black and starch) and silica sol and boric acid as the precursor raw materials. Basedon thermodynamic analysis and calculation, the effects of different carbon sources and reaction temperatures on the mass lossrate, phase composition, and microstructure of SiC-B4C ultrafine composite powders were comparatively studied. Resultsshowed that the optimum conditions for synthesizing SiC-B4C composite powders with carbon black as the carbon source were1550 ºC for 2 h, whereas the optimum conditions for synthesizing SiC-B4C composite powders with starch as the carbon sourcewere 1450 ºC-1550 ºC for 2 h. The powder samples synthesized with carbon black as the carbon source at 1550 ºC were mainlycomposed of flaky, columnar-like, spherical, and irregular polyhedral particles (about 100-200 nm in diameter). Mutualcohesion or agglomeration between particles was minimal. In the powder samples synthesized at 1550 ºC with an excess of 10wt% starch, in addition to a certain amount of flaky, spherical, and other irregular structure particles, a certain amount ofuniform, slender whiskers (about 50-100 nm in diameter) and a certain phenomenon of lap and winding between the whiskerswere noted. The powder samples synthesized at 1550 ºC with an excess of 20 wt% starch had no whisker-like substance.

로켓 노즐목 소재 C/SiC 복합재 고온 파괴 특성

윤동현(Dong Hyun Yoon),이정원(Jeong Won Lee),김재훈(Jae Hoon Kim),신인철(Ihn Cheol Sihn),임병주(Byung Joo Lim) 대한기계학회 2016 大韓機械學會論文集A Vol.40 No.11

고체 추진 기관에서 로켓 노즐은 고온 연소가스에 노출된다. 따라서 고온에서 기능을 발휘할 수 있는 적절한 재료의 선택이 중요하다. 탄소 섬유 강화 실리콘 카바이드 복합재(C/SiC)가 로켓 노즉목에 적용을 위해 연구되어 왔다. 그러나 전형적인 구조 재료들과 비교할 때 C/SiC 복합재는 준취성 거동을 가지고 고온에서 산화의 영향으로 인해 강도와 인성 관점에서 상대적으로 취약한 점이 있다. 그러므로 실제 적용을 위해 C/SiC 복합재의 열, 기계적인 특성을 평가하는 것은 중요하다. 본 논문에서는 액화 실리콘 용침(LSI) 공정을 통해 만들어진 C/SiC 복합재의 고온에서의 파괴 거동을 조사하는 실험적인 방법을 설명한다. 특히 온도와 하중, 산화 조건 그리고 탄소 섬유의 방향을 주요 변수로 설정하여 파괴 특성을 조사하였다. 파단면 분석은 SEM 촬영을 통하여 수행하였다. In a solid propulsion system, the rocket nozzle is exposed to high temperature combustion gas. Hence, choosing an appropriate material that could demonstrate adequate performance at high temperature is important. As advanced materials, carbon/silicon carbide composites (C/SiC) have been studied with the aim of using them for the rocket nozzle throat. However, when compared with typical structural materials, C/SiC composites are relatively weak in terms of both strength and toughness, owing to their quasi-brittle behavior and oxidation at high temperatures. Therefore, it is important to evaluate the thermal and mechanical properties of this material before using it in this application. This study presents an experimental method to investigate the fracture behavior of C/SiC composite material manufactured using liquid silicon infiltration (LSI) method at elevated temperatures. In particular, the effects of major parameters, such as temperature, loading, oxidation conditions, and fiber direction on strength and fracture characteristics were investigated. Fractography analysis of the fractured specimens was performed using an SEM.