• 한국군사과학기술학회지
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• 제20권5호
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• pp.620-632
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• 2017

A chemical vapor curing method(CVC) was developed to cure polycarbosilane(PCS) fibers by using cyclohexene vapour as a non-oxygen active reactant, instead of air in oder to prepare the silicon carbide(SiC) fiber with low oxygen content. A cross-linked PCS fibers by cyclohexene vapor showed a completely different variation in IR spectra in comparison to the air-cured PCS fiber. CVC method resulted in less than 3 wt% in oxygen content. In this experiment conditions, The average tensile strength and modulus of SiC fiber obtained by CVC had 1995 MPa and 183 GPa respectively, which is higher than that of SiC fiber prepared by air-curing process.

• Composites Research
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• 제33권3호
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• pp.101-107
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• 2020

본 논문에서는 탄화규소로 코팅된 탄소-탄소복합재료의 단열 특성을 고찰하였다. 탄소-탄소 복합재료 상에 탄화규소를 화학증착법(CVD)법으로 코팅하였다. 먼저 탄화규소로 코팅한 복합재와 코팅되지 않은 복합재에 대해, 공기 중에서 1350℃의 온도를 급작스럽게 부가하였을 때의 단열특성을 서로 비교하는 연구를 수행하였다. 또한 본 연구에서는 최대 1700℃ 및 2000℃의 온도에 복합재의 표면을 노출시키는 고온 버너실험을 수행하였다. 버너실험 전, 후의 무게를 측정하여 무게변화를 고찰하였다. 고온 버너실험 후 탄소-탄소 복합재 및 탄화규소로 코팅된 복합재의 손상여부를 비교, 고찰하였다. 그 결과 2000℃의 온도에 노출 시 탄화규소 코팅재에서 박리, 균열, 공동 등의 결함손상들이 발견되었으나, 고온으로부터 탄소-탄소 복합재를 보호하는데 효과적이었다.

• 자원리싸이클링
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• 제31권6호
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• pp.60-65
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• 2022

본 논문에서는 반도체용 실리콘 기판 가공 과정에서 발생한 슬러지 재활용을 위해 탄화 반응에 의한 탄화규소(SiC) 분말 합성 공정을 적용한 결과를 제시하고자 한다. 입수한 슬러지는 실리콘 기판을 탄화규소 연마재를 사용하여 가공하는 과정에서 발생하므로 실리콘과 탄화규소가 혼합된 형태였으며 가공 설비로부터 발생한 철 불순물이 포함되어 있었다. 슬러지는 절삭유가 포함되어 있어 점성이 있는 유체 형태였으며 대기 건조를 통해 분말 형태로 변화된 후 산 세정을 통한 철 성분 제거 및 탄화에 의한 탄화규소 분말 합성 과정을 거치게 된다. 슬러지에 포함된 실리콘과 탄화규소의 비율에 따라 탄화 반응에 필요한 탄소량이 달랐으며 탄화규소의 함량이 커질수록 탄소 부족 현상으로 인해 비화학량론적 탄화물(SiC_x, x<1) 형성이 촉진되어 순수한 탄화규소 합성이 이루어지지 않는 것을 확인하였다. 이러한 비화학량론적 탄화물은 잉여 탄소 추가와 고에너지 밀링에 의한 탄화 반응성 증가를 통해 제거할 수 있었으며 결과적으로 산 세정과 밀링 과정에 의해 슬러지로부터 순수한 탄화규소 분말 합성이 가능함을 확인할 수 있었다.

• 한국세라믹학회지
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• 제35권12호
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• pp.1249-1256
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• 1998

${\beta}$-Silicon carbide(${\beta}$-SiC) whiskers could be synthesized by the carbothermal reduction of kaolin at tem-peratures between 1400 and 1500$^{\circ}C$. The whiskers were grown up to about 1150 of aspect ratio by VS mechanism (showing tapering tips) and to about 45 of that by VLS mechanism (showing round droplet tips) respectively. Hydrocarbon like methane in the reaction atmosphere promoted the formation of gaseous il-icon monoxide(SiO) from silicon dioxide(SiO2) and subsequently reacted with it to form whiskers. The for-mation of ${\beta}$-SiC whiskers increased with increasing carbon content(to 30 wt%) and reaction temperatures. The max. yield of ${\beta}$-SiC whiskers was 15% at 1500$^{\circ}C$ under 20%CH4/80%H2.

• 한국재료학회지
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• 제33권6호
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• pp.257-264
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• 2023

To develop a high capacity lithium secondary battery, a new approach to anode material synthesis is required, capable of producing an anode that exceeds the energy density limit of a carbon-based anode. This research synthesized carbon nano silicon composites as an anode material for a secondary battery using the RF thermal plasma method, which is an ecofriendly dry synthesis method. Prior to material synthesis, a silicon raw material was mixed at 10, 20, 30, 40, and 50 wt% based on the carbon raw material in a powder form, and the temperature change inside the reaction field depending on the applied plasma power was calculated. Information about the materials in the synthesized carbon nano silicon composites were confirmed through XRD analysis, showing carbon (86.7~52.6 %), silicon (7.2~36.2 %), and silicon carbide (6.1~11.2 %). Through FE-SEM analysis, it was confirmed that the silicon bonded to carbon was distributed at sizes of 100 nm or less. The bonding shape of the silicon nano particles bonded to carbon was observed through TEM analysis. The initial electrochemical charging/discharging test for the 40 wt% silicon mixture showed excellent electrical characteristics of 1,517 mAh/g (91.9 %) and an irreversible capacity of 133 mAh/g (8.1 %).

• Advances in nano research
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• 제12권2호
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• pp.213-221
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• 2022

Silicon carbide (SiC) is a binary carbon-silicon compound. In its two-dimensional form, monolayer SiC is composed of a monolayer carbon and silicon atoms constructed as a honeycomb lattice. SiC has recently been receiving increasing attention from researchers owing to its intriguing electronic properties. In this present work, SiC nanoribbons (SiCNRs) are modelled and simulated to obtain accurate electronic properties, which can further guide fabrication processes, through bandgap engineering. The primary objective of this work is to obtain the electronic properties of monolayer SiCNRs by applying numerical computation methods using nearest-neighbour tight-binding models. Hamiltonian operator discretization and approximation of plane wave are assumed for the models and simulation by applying the basis function. The computed electronic properties include the band structures and density of states of monolayer SiCNRs of varying width. Furthermore, the properties are compared with those of graphene nanoribbons. The bandgap of ASiCNR as a function of width are also benchmarked with published DFT-GW and DFT-GGA data. Our nearest neighbour tight-binding (NNTB) model predicted data closer to the calculations based on the standard DFT-GGA and underestimated the bandgap values projected from DFT-GW, which takes in account the exchange-correlation energy of many-body effects.

• 한국표면공학회지
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• 제43권1호
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• pp.36-40
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• 2010

The SiO vapor that was generated from a mixture of Si and $SiO_2$ was reacted at $1350^{\circ}C$ for 2 h under vacuum with carbon nanofibers to produce SiC nanofibers having an average diameter of 100~200 nm. In order to understand the gas corrosion behavior, SiC nanofibers were exposed to air up to $1000^{\circ}C$. SiC oxidized to amorphous $SiO_2$, but its oxidation resistance was inferior unlike bulk SiC, because of high surface area of nanofibers. When SiC nanofibers were exposed to Ar-1% $SO_2$ atmosphere, SiC oxidized to amorphous $SiO_2$, without forming $SiS_2$, owing to the thermodynamic stability of $SiO_2$.

• 한국세라믹학회지
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• 제28권8호
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• pp.577-584
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• 1991

Among various forming techniques for ceramics, we have studied the slip casting method for the binary system of SiC and carbon. The stability of the slip of silicon carbide and carbon were investigated by measurements of zeta potential, viscosity, sedimentation height, and also studied as functions of PH and amounts of dispersants. A preform of SiC and C was prepared by slip casting and heat treatment at 400∼600$^{\circ}C$ under N2 gas. The preform was reacted with Si metal at 1550$^{\circ}C$, 10-1 mmHg to give rise a reaction bonded SiC with a density of 3.0g/㎤ and a bending strength of 580 MPa.

• 한국주조공학회지
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• 제17권4호
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• pp.371-378
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• 1997

The study for direct synthesis of TaC carbide which was a reaction product of tantalum and carbon in the cast iron was performed. Cast iron which has hypo-eutectic composition was cast bonded in the metal mold with tantalum thin sheet of thickness of $100{\mu}m$. The contents of carbon and silicon of cast iron matrix was controlled to have constant carbon equivalent of 3.6. The chracteristics of microstructure and the formation mechanism of TaC carbide in the interfacial reaction layer in the cast iron/tantalum thin sheet heat treated isothermally at $950^{\circ}C$ for various time were examined. TaC carbide reaction layer was grown to the dendritic morphology in the cast iron/tantalum thin sheet interface by the isothermal heat treatment. The composition of TaC carbide was 48.5 at.% $Ti{\sim}48.6$ at.% C-2.8 at.% Fe. The hardness of reaction layer was MHV $1100{\sim}1200$. The thickness of reaction layer linearly increased with increasing the total content of carbon in the cast iron matrix and isothermal heat treating time. The growth constant for TaC reaction layer was proportional to the log[C] of the matrix. The formation mechanism of TaC reaction layer at the interface of cast iron/tantalum thin sheet was proved to be the interfacial reaction.

• 한국재료학회지
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• 제31권5호
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• pp.301-311
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• 2021

The conversion of all carbon preforms to dense SiC by liquid infiltration can become a low-cost and reliable method to form SiC-Si composites of complex shape and high density. Reactive sintered silicon carbide (RBSC) is prepared by covering Si powder on top of 0.5-5.0 wt% Y₂O₃-added carbon preforms at 1,450 and 1,500℃ for 2 hours; samples are analyzed to determine densification. Reactive sintering from the Y₂O₃-free carbon preform causes Si to be pushed to one side and cracking defects occur. However, when prepared from the Y₂O₃-added carbon preform, an SiC-Si composite in which Si is homogeneously distributed in the SiC matrix without cracking can be produced. Using the Si + C = SiC reaction, 3C and 6H of SiC, crystalline Si, and Y₂O₃ phases are detected by XRD analysis without the appearance of graphite. As the content of Y₂O₃ in the carbon preform increases, the prepared RBSC accelerates the SiC conversion reaction, increasing the density and decreasing the pores, resulting in densification. The dense RBSC obtained by reaction sintering at 1,500 ℃ for 2 hours from a carbon preform with 2.0 wt% Y₂O₃ added has 0.20 % apparent porosity and 96.9 % relative density.