• 한국분말재료학회지
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• 제16권6호
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• pp.416-423
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• 2009

Diamond/SiC composites are appropriate candidate materials for heat conduction as well as high temperature abrasive materials because they do not form liquid phase at high temperature. Diamond/SiC composite consists of diamond particles embedded in a SiC binding matrix. SiC is a hard material with strong covalent bonds having similar structure and thermal expansion with diamond. Interfacial reaction plays an important role in diamond/SiC composites. Diamond/SiC composites were fabricated by high temperature and high pressure (HPHT) sintering with different diamond content, single diamond particle size and bi-modal diamond particle size, and also the effects of composition of diamond and silicon on microstructure, mechanical properties and thermal properties of diamond/SiC composite were investigated. The critical factors influencing the dynamics of reaction between diamond and silicon, such as graphitization process and phase composition, were characterized. Key factor to enhance mechanical and thermal properties of diamond/SiC composites is to keep strong interfacial bonding at diamond/SiC composites and homogeneous dispersion of diamond particles in SiC matrix.

• 한국재료학회지
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• 제25권5호
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• pp.258-263
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• 2015

To fabricate porous SiC-Si composites for heating element applications, both SiC powders and Si powders were mixed and sintered together. The properties of the sintered SiC-Si body were investigated as a function of SiC particle size and/or Si particle contents from 10 wt% to 40 wt%, respectively. Porous SiC-Si composites were fabricated by Si bonded reaction at a sintering temperature of $1650^{\circ}C$ for 80 min. The microstructure and phase analysis of SiC-Si composites that depend on Si particle contents were characterized using scanning electron microscope and X-ray diffraction. The electrical resistivity of SiC-Si composites was also evaluated using a 4-point probe resistivity method. The electrical resistivity of the sintered SiC-Si body sharply decreased as the amount of Si addition increased. We found that the electrical resistivity of porous SiC-Si composites is closely related to the amount of Si added and at least 20 wt% Si are needed in order to apply the SiCSi composites to the heating element.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 추계학술대회 논문집 전기물성,응용부문
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• pp.191-193
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• 2004

The composites were fabricated, respectively, using 61vol.% SiC-39vol.% $TiB_2$ and using 61vol.% SiC-39vol.% $ZrB_2$ powders with the liquid forming additives of 12wt% $Al_2O_3+Y_2O_3$ by hot pressing annealing at $1650^{\circ}C$ for 4 hours. Reactions between SiC and transition metal $TiB_2$, $ZrB_2$ were not observed in this microstructure. The result of phase analysis of composites by XRD revealed SiC(6H, 3C), $TiB_2$, $ZrB_2$ and $YAG(Al_5Y_3O_{12})$ crystal phase on the SiC-$TiB_2$, and SiC-$ZrB_2$ composites. The ${\beta}\;{\alpha}$-SiC phase transformation was occurred on the $SiC-TiB_2$, $SiC-ZrB_2$ composites. The relative density, the flexural strength and Young's modulus showed respectively value of 98.57%, 226.06Mpa and $86.37{\times}10^3Mpa$ in SiC-$ZrB_2$ composites.

• Composites Research
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• 제32권3호
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• pp.158-162
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• 2019

본 연구에서는 용융가압함침 공정을 이용하여 고체적률의 TiC 입자가 균일 분산된 Inconel 718 금속복합재료를 제조하고, 미세조직 및 기계적 특성을 분석하였다. 약 55 vol%의 TiC가 균일하게 분산된 TiC-Inconel 718 복합재료를 제조함으로써 Inconel 718 대비 우수한 경도 및 압축강도 특성을 나타내었으며, 이는 기지에 고용된 합금원소인 Mo 및 Nb이 TiC 강화재 내부로 확산 고용되어 우수한 계면 특성을 가지는 core-rim 구조의 TiC 형성에 의한 것으로 판단된다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 춘계학술대회 논문집 유기절연재료 전자세라믹 방전플라즈마 연구회
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• pp.118-122
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• 2001

The ${\beta}-SiC+TiB_2$ ceramic electroconductive composites were pressureless-sintered and annealed by adding 12wt% $Al_2O_3+Y_2O_3$(6 : 4wt%) powder as a function of sintering temperature. The relative density is over 78.83% of the theoretical density and increased with increasing sintering temperature. The phase analysis of the composites by XRD revealed of $\alpha$-SiC(6H), $TiB_2$, $Al_5Y_2O_{12}$ and $\beta$-SiC(15R). Flexural strength showed the highest of 140 MPa for composites sintered at $1900^{\circ}C$. The vicker's hardness increased with increasing sintering temperature and showed the highest of 4.07 GPa at $1900^{\circ}C$. Owing to YAG, the fracture toughness showed the highest of 4.07 $MPa{\cdot}m^{1/2}$ for composites at $1900^{\circ}C$. The electrical resistivity was measured by the Pauw method from $25^{\circ}C$ to $700^{\circ}C$. The electrical resistivity of the composites showed the PTCR(Positive Temperature Coefficient Resistivity).

• 한국분말재료학회지
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• 제2권1호
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• pp.44-52
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• 1995

Effects of the extrusion temperature and die angle on the tensile properties of SiCIyAl composites in powder extrusion have been investigated. SiCP/Al composites were extruded at various extrusion temperatures (450, 500, $550^{\circ}C$) under the extrusion ratio of 25 : 1. The ram speed was maintained at 13 cm/min for all the extrusion conditions. The surface of the extruded rod appeared to be smooth without tearing at 450 and 50$0^{\circ}C$, whereas it was very rough due to tearing at $550^{\circ}C$. It was found that the tensile strength and elongation of the composites extruded at $500^{\circ}C$ are greater than those of composites extruded at $450^{\circ}C$ This is due to the easier plastic deformation of composite extruded at $500^{\circ}C$, compared with the composites extruded at $450^{\circ}C$. The effect of die angle was examined under 20=60, 120, $180^{\circ}$die angles at extrusion temperature of $500^{\circ}C$ under 25:1 extrusion ratio. The tensile strength of the composites extruded with 20=$60^{\circ}$approved to be higher than that of the composties extruded with 28 : 120 and $180^{\circ}$This is attributable to the higher extrusion pressure, which mixed composite powders could be densely consolidated at elevated temperatures, resulting from high friction force between billet and sliding surface of conical die.

• Composites Research
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• 제33권5호
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• pp.247-250
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• 2020

본 연구에서는 액상가압성형 공정을 이용하여 SiC 연속섬유가 강화된 마그네슘 복합재료의 제조 가능성을 검토하였다. 액상가압성형 공정을 이용하여 SiC 섬유가 균일 분산된 AZ91 복합재료를 제조하였으며 열처리를 통하여 석출상을 제어하였다. SiC 섬유와 기지합금의 계면에 연속적인 Mg₂Si상이 형성되면서 계면 결합력이 향상되었고, 제조된 복합재료의 상온 인장강도는 479 MPa로 우수한 기계적 특성을 나타내었다.

• 한국세라믹학회지
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• 제32권10호
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• pp.1194-1202
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• 1995

The influences of TiC additions to the α-SiC on microstructural, mechanical, and electrical properties were investigated. Electrical discharge machinability of SiC-TiC composites was also studied. Samples were prepared by adding 30, 45, 60 wt.% TiC particles as a second phase to a SiC matrix. Sintering of SiC-TiC composites was done by hot pressing under a vacuum atmospehre from 1000 to 2000℃ with a pressure of 32 MPa and held for 90 minutes at 2000℃. Samples obtained by hot pressing were fully dense with the relative densities over 99% except 60wt.% TiC samples. Flexural strength and fracture toughness of the samples were increased with the TiC content. In case of SiC samples containing 45 wt.% TiC, the fracture toughness showed 90% increase compared to that of monolithic SiC sample. The crack propagation and crack deflection were observed with a SEM for etched samples after Vicker's indentation. The electrical resistivities of SiC-TiC composites were measured utilizing the four-point probe. The electrical dischage machining of composites was also conducted to evaluate the machinability.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제50권11호
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• pp.544-549
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• 2001

The mechanical and electrical properties of the hot-pressed and pressureless annealed SiC-39vo1.%TiB$_2$electroconductive ceramic composites were investigated as functions of the liquid additives of $Al_2O_3+Y_2O_3$ and the sintering temperature. The result of phase analysis for the SiC-39vo1.%TiB$_2$ composites by XRD revealed $\alpha -SiC(6H),\; TiB_2,\; and YAG(Al_5Y_3O_{12})$ crystal phase. The relative density of SiC-39vo1.% $TiB_2$ composites was increased with increased $Al_2O_3+Y_2O_3$ contents. The fracture toughness showed the highest value of $7.8 MPa.m_{1/2}$ for composites added with 12 wt% $Al_2O_3+Y_2O_3$additives at $1750^{\circk}C$. The electrical resistivity of the SiC-39vo1.%$TiB_2$composites was all positive temperature coefficient resistance(PTCR) in the temperature range of $25S^{\circ}C \;to\; 700^{\circ}C$.

• 한국표면공학회지
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• 제48권5호
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• pp.218-226
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• 2015

The goal of this study is to investigate a metal cladding that contains SiC composites as a protective layer and analysis the characteristics of the specimens on high temperature oxidation To make SiC composites, the current process needs a high temperature (about $1100^{\circ}C$) for the infiltration of fixing materials such as SiC. To improve this situation, we need a low temperature process. In this study, we developed a low temperature process for making SiC composites on the metal layer, and we have made two kinds: cladding with protective SiC composites made by polycarbosilane(PCS), and a PCS filling method using supercritical carbon dioxide. A corrosion test at $1200^{\circ}C$ in a mixed steam and Ar atmosphere was performed on these specimens. The result show that the cladding with protective SiC composites have excellent oxidation suprression rates. This study can be said to have developed new metal cladding with enhanced durability by using SiC composite as protective films of metal cladding instead of simple coating film.