• Journal of Powder Materials
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• v.16 no.6
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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.

• Korean Journal of Materials Research
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• v.25 no.5
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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.

• Proceedings of the KIEE Conference
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• 2004.11a
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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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• v.32 no.3
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• pp.158-162
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• 2019

Titanium carbide (TiC) reinforced Inconel 718 matrix composites were successfully fabricated by a novel liquid pressing infiltration process. Microstructure and mechanical properties of the fabricated 55 vol% TiC-Inconel 718 composite are analyzed. The composite exhibits superior mechanical properties, such as hardness and compressive strength as compared with Inconel 718. It is believed that Mo and Nb, which are alloying elements in the matrix, diffuse and solidify into the TiC reinforcement, resulting in generation of core-rim structure with excellent interfacial properties.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05c
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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).

• Journal of Powder Materials
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• v.2 no.1
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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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• v.33 no.5
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• pp.247-250
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• 2020

In this study, the possibility of manufacturing a magnesium (Mg) composites reinforced with continuous silicon carbide (SiC) fibers was examined using a liquid pressing process. We fabricated uniformly dispersed SiC fiberAZ91 composites using a liquid phase pressing process. Furthermore, the precipitates were controlled through heat treatment. As a continuous Mg₂Si phase was formed at the interface between the SiC fiber and the AZ91 matrix alloy, the interfacial bonding strength was improved. The tensile strength at room temperature of the prepared composite was 479 MPa, showing excellent mechanical properties.

• Journal of the Korean Ceramic Society
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• v.32 no.10
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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.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.11
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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 $25S^{\circ}C \;to\; 700^{\circ}C$.

• Journal of the Korean institute of surface engineering
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• v.48 no.5
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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.