• Composites Research
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• v.13 no.6
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• pp.23-29
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• 2000

The internal residual stresses within the multilayered structure with sharp interface induced by the difference in thermal expansion coefficient between the materials of adjacent layers often provide the source of failure such as delamination of interfaces etc. Recent development of the multilayered structure with functionally graded interface would be the solution to prevent this kind of failure. However a systematic thermo-mechanical analysis is needed for the customized structural design of multilayered structure. In this study, theoretical model for the thermo-mechanical analysis is developed for multilayered structures of the $Al-SiC_p$ functionally graded composite for electronic packaging. The evolution of curvature and internal stresses in response to temperature variations is presented for the different combinations of geometry. The resultant analytical solutions are used for the optimal design of the multilayered structures with functionally graded interface as well as with sharp interface.

• Korean Journal of Materials Research
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• v.19 no.7
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• pp.403-406
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• 2009

The friction characteristics of automotive brake friction materials that contained different ceramic content were investigated. Several kinds of raw materials, such as resin-based binder, reinforcing fiber, friction restraint, abrasive, and filling materials were mixed, pressed, and heated in order to make the brake friction materials. The contents of SiC and $BaSO_4$ changed from 5 vol% to 20 vol%, respectively. In addition to this, the content of $Al_2O_3$ adjusted from 1 vol% to 16 vol%. The surface morphology of the SiC containing sample appeared rough while more debris was observed when the contents of SiC increased. This implies that the SiC containing brake composite was not adequate for the automobile. However, the relatively smooth surface was observed in samples that contained the $Al_2O_3$. But the roughness was low with a content of 11 vol% $Al_2O_3$ compared to the other samples. This is consistent with the abrasive properties of the samples. In the case of $BaSO_4$ containing samples, the smoothes surface was observed in the contents of 15 vol% $BaSO_4$. Thus, it was concluded that the 11 vol% $Al_2O_3$ and 15 vol% $BaSO_4$ containing composite would be the optimum content for the brake composite. Similar to the results of the surface morphology, the abrasion resistance consistently decreased when the content of SiC increased. On the contrary, the sample that contained 11 vol% $Al_2O_3$ and 15 vol% $BaSO_4$ showed the highest abrasion resistance compared to the other samples.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.9
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• pp.1053-1057
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• 2012

In this study, the temperature-dependency of the tensile properties of a glass fiber reinforced plastic (GFRP) used in wind turbine blades was examined. The tensile strength, elastic modulus, and Poisson's ratio of the tensile specimen manufactured from uniaxial ($0^{\circ}$) and triaxial ($0/{\pm}45^{\circ}$) laminate composite plates were measured at four different testing temperatures-room temperature, $-30^{\circ}C$, $-50^{\circ}C$, and $60^{\circ}C$. It was found that the tensile strengths and elastic moduli of the uniaxial laminates were greater than those of the triaxial laminates over the testing temperature range. The tensile strength of the two laminates was significantly dependent on the testing temperature, while the dependency of the elastic modulus on the temperature was insignificant. Furthermore, it could be considered that the Poisson's ratio changed slightly with a change in the testing temperature.

• Korean Chemical Engineering Research
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• v.59 no.3
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• pp.326-332
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• 2021

In this study, a spherical carbon composite material containing nano-silicon was synthesized using hydrothermal synthesis, and coated with petroleum pitch to prepare an anode material to investigate the electrochemical characteristics. Hydrothermal synthesis was performed by varying molar concentration, and the pitch was coated using THF as an organic solvent to prepare a composite material. The physical properties of anode materials were analyzed using SEM, EDS, XRD and TGA, and the electrochemical performances were investigated by cycle, C-rate, cyclic voltammetry and electrochemical impedance tests in 1.0 M LiPF₆ electrolyte (EC : DMC : EMC = 1 : 1 : 1 vol%). The pitch-coated silicon/carbon composite (Pitch@Si/C-1.5) with sucrose of 1.5 M showed a spherical shape. In addition, a high initial capacity of 1756 mAh/g, a capacity retention ratio of 82% after 50 cycles, and an excellent rate characteristic of 81% at 2 C/0.1 C were confirmed.

• Proceedings of the Korean Society For Composite Materials Conference
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• 1999.04a
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• pp.193-196
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• 1999

• Journal of Korea Foundry Society
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• v.17 no.2
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• pp.180-187
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• 1997

The influence of solidification condition on the segregation of SiC particles in the $Al-xSi/6wt%SiC_p$(x: 6, 10, 14, 18${\cdot}$wt%) composites was investigated in the study. The results are as follows: 1) During the counter-gravity unidirectional solidification of $Al-Si/SiC_p$ composites melt, most of the SiC particles are pushed to the top of the casting. 2) The SiC particles pushing in the $Al-Si/SiC_p$ composite melts are not observed, when the interface velocity of melts increases more than 1.41 ${\mu}m/sec$. 3) The SiC particles are entrapped in the interdendrite regions, when the sizes of SiC particles in the $Al-Si/SiC_p$ composites are large than ${\varphi}22{\mu}m$.

• Journal of the Korean Ceramic Society
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• v.29 no.10
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• pp.791-796
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• 1992

SiC(p)-TiC(p) composites were prepared by gas pressure sintering technique. B4C powder and phenolic resin were added as sintering aids by 0.3 wt%-B and 3 wt%-C, TiC powder were dispersed in SiC by 0, 10, 20, 30 and 50 vol%. Flextural strength, fracture toughness and theoretical density of 70 vol% SiC-30 vol% TiC composite sintered at 220$0^{\circ}C$ by gas pressing were 540 MPa, 5.5 MPa.m1/2 and 98.8% respectively.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.2
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• pp.92-97
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• 1999

The mechanical and electrical properties of the hot-pressed and annealed $\beta-Sic$+39vol.%$ZrB_2$ electroconductive ceramic composites were investigated as a function of the liquid forming additives of $Al_2O_3+Y_2O_3(6:4wt%)$. In this microstructures, no reactions and elongated $\alpha$-SiC grains with equiaxed $ZrB_2$, gains were observed between $\beta-SiC$ and $ZrB_2$, and the relative density was over 97.6% of the theoretical density. Phase analysis of the composites by XRD revealedmostly of $\alpha$-SiC(6H, 4H), $ZrB_2$, and weakly $\beta-SiC$(15R) phase. The fracture toughness decreased with increasing $Al_2O_3+Y_2O_3$ contents and showed the highest of $6.37MPa.m^{\fraction ane-half}$ for composite added with 4wt% $Al_2O_3+Y_2O_3$ additives at room temperature. The electrical resistivity increased with increasing $Al_2O_3+Y_2O_3$contents and showed the lowest of $1.51\times10^{-4}\Omega.cm$ for composite added with $Al_2O_3+Y_2O_3$ additives at $25^{\circ}C$. This reason is the increasing tendency of pore formation according to amount of liquid forming additives $Al_2O_3+Y_2O_3$. The electrical resistivity of the composites was all positive temperature coefficient resistance(PTCR) against temperature up to $700^{\circ}C$.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.04a
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• pp.182-185
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• 2004

In this work, the effect of chemical treatments on surface properties of SiC was investigated in mechanical interfacial properties of carbon fibers-reinforced composites. The surface properties of the SiC were determined by acid/base values and contact angles. The thermal stabilities of carbon fibers-reinforced composites were investigated by thermogravimetric analysis (TGA). Also, the mechanical interfacial properties of the composites were studied in interlaminar shear strength (ILSS) and critical strain energy release rate mode II $(G_{IIC})$ measurements. As a result, tile acidically treated SiC (A-SiC) had higher acid value than that of untreated SiC (V-SiC) or basically treated SiC (B-SiC). According to the contact angle measurements, it was observed that chemical treatments led to an increase of surface free energy of the SiC surfaces, mainly due to the increase of the specific (polar) component. The mechanical interfacial properties of the composites, including ILSS and $(G_{IIC})$, had been improved in the specimens treated by chemical solutions. These results were explained that good wetting played an important role in improving the degree of adhesion at interfaces between SiC and epoxy resin matrix.

• Polymer(Korea)
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• v.38 no.6
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• pp.782-786
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• 2014

Various kinds of thermal conductive ceramic/polymer composites (aluminum nitride, aluminum oxide, boron nitride, and silicon carbide/epoxy) were prepared by a casting method and their optical images were observed by FE-SEM. Among these, SiC/epoxy composite shows inhomogeneous dispersion features of SiC and air voids in the epoxy matrix layer, resulting in undesirable thermal conductive properties. To enhance the thermal conductivities of SiC/epoxy composites, the epoxy wetting method which can directly infiltrate the epoxy droplet onto filtrated SiC cake was employed to fabricate the homogeneously dispersed SiC/epoxy composite for ideal thermal conductive behavior, with maximum thermal conductivity of 3.85W/mK at 70 wt% of SiC filler contents.