• Journal of the Korean Ceramic Society
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• v.33 no.8
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• pp.921-927
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• 1996

The liquid-phase concentration from the interior to the surface region and its influence on the microstructural changes were investigated in pressureless sintered $\beta$-SiC Surface reaction-layer was formed by reaction of packing powder and volatile components on the surface during sintering which was induced the concentration of liquid-phase in the surface regions. The microstructural changes between the surface region and the interior were appeared in sintered specimen which was resulted from the difference of liquid-phase content during sintering. Microstructural changes were observd with the depth of about 250${\mu}{\textrm}{m}$ from he surface. The grain size and aspect ratio of SiC in the interior are larger than those in the surface region and the rate of transforma-tion of $\beta$-to $\alpha$-SiC during sintering is higher in the interior than that in the surface region.

• Journal of the Korean Ceramic Society
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• v.31 no.6
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• pp.629-636
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• 1994

The ferrimagnetic glass-ceramics in the system Fe2O3-CaO-SiO2 for hyperthermia were investigated. Glasses could be prepared up to the content of 40 wt% of Fe2O3 and below the weight ratio of 1.0 of CaO/SiO2. The maximum saturation magnetization and the maximum coercive force were 29.85 emu/g and 340.1 Oe respectively, for a glass 40Fe2O3.20CaO.40SiO2 composition heat-treated at 95$0^{\circ}C$ for 8 hours. And for a glass 40Fe2O3.30CaO.30SiO2 composition the maximum saturation magnetization and the maximum coercive force were 18.47 emu/g and 374.4 Oe heat-treated at 1,00$0^{\circ}C$ and 90$0^{\circ}C$ for 8 hours respectively. The maximum hysteresis loss was 1,726.3 cal/g for a glass 40Fe2O3.20CaO.40SiO2 composition heat-treated at 95$0^{\circ}C$ for 8 hours. It was found that the ferrimagnetic Fe2O3.CaO.SiO2 glass-ceramics was little injurious to human body as results of biocompatibility test and biotoxicity test.

• Korean Journal of Materials Research
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• v.8 no.6
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• pp.513-519
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• 1998

Zr-Si binary alloys containing 0.01 to O.lwt.%Si were prepared to investigate the effect of Si on the corrosion behavior of Zr. Corrosion test was performed in pure water at 36$0^{\circ}C$ under a pressure of 2660psi for 100days. The alloys containing 0.01 wt. % and 0.05wt. %Si had the black and uniform oxide film and didn't show the transition of corrosion rate. However. the alloys containing O.lwt.%Si had white oxide film and showed the trasition of corrosion rate at 70 days corrosion test. The weight gain increased with the increasing Si content from 0.01 to 0.1 wt.%. The variation of Si contents had no effect on changing the oxide structure but had significant effect on the electrical resistivity of oxide. The electrical resistivity decreased with increasing Si content. The fraction of precipitates in the Zr-Si binary alloys. identified as tetragonal $Zr_{3}$Si increased with increasing Si content. The increase of the volume fraction of precipitates is thought to be responsible for the increase of weight gain due to short circuit effect of precipitate.

• Journal of the Korean Electrochemical Society
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• v.9 no.3
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• pp.107-112
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• 2006

Si-C composites were prepared by the carbonization of silicon powder covered by polyaniline(PAn). Physical and electrochemical properties of the Si-C composites were characterized by the particle size analysis, X-ray diffraction technique, scanning electron microscope, and electrochemical test of battery. The average particle size of the Si was increased by the coating of PAn and somewhat reduced by the carbonization to give silicone-carbon composites. XRD analysis' results were confirmed co-existence of crystalline silicon and amorphous-like carbon. SEM photos showed that the silicon particle were well covered with carbonacious materials depend on the PAn content. Si-C|Li cells were fabricated using the Si-C composites and were tested using the galvanostatic charge-discharge test. Si-C|Li cells gave better electrochemical properties than that of Si|Li cell. Si-C|Li cell using the Si-C from HCl undoped PAn Precursor showed better electrochemical properties than that from HCl doped PAn Precursor. Using the electrolyte containing FEC as an additive, the initial discharge capacity was increased. After that the galvanostatic charge-discharge test with the GISOC(gradual increasing of the state of charge) condition was carried out. Si-C(Si:PAn:50:50 wt. ratio)|Li cell showed 414 mAh/g of the reversible specific capacity, 75.7% of IIE(initial intercalation efficiency), 35.4 mAh/g of IICs(surface irreversible specific capacity).

• Journal of the Korean Ceramic Society
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• v.52 no.4
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• pp.243-247
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• 2015

Si(Al)ON precursor was synthesized by formation of new Si-N bond using organoaluminum imine and liquid type poly(phenyl carbosilane). It was decomposed between $200-600^{\circ}C$, and the ceramic yield was 51% after pyrolysis. 150 - 200 nm in thickness of coating film was obtained by spin coating method. The precursor was easily oxidized during process because it was unstable in air. However the oxygen content was limited to 0.5 - 0.7 to silicon in heat treatment step. Even though the content of nitrogen was decreased by pyrolysis, Al-N and Si-N bonds were formed in ammonia atmosphere, and Si(Al)ON film was formed with 0.2 in content to silicon.

• Nuclear Engineering and Technology
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• v.45 no.7
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• pp.827-838
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• 2013

Interaction layer growth between U-Mo alloy fuel particles and Al in a dispersion fuel is a concern due to the volume expansion and other unfavorable irradiation behavior of the interaction product. To reduce interaction layer (IL) growth, a small amount of Si is added to the Al. As a result, IL growth is affected by the Si content in the Al matrix. In order to predict IL growth during fabrication and irradiation, empirical models were developed. For IL growth prediction during fabrication and any follow-on heating process before irradiation, out-of-pile heating test data were used to develop kinetic correlations. Two out-of-pile correlations, one for the pure Al matrix and the other for the Al matrix with Si addition, respectively, were developed, which are Arrhenius equations that include temperature and time. For IL growth predictions during irradiation, the out-of-pile correlations were modified to include a fission-rate term to consider fission enhanced diffusion, and multiplication factors to incorporate the Si addition effect and the effect of the Mo content. The in-pile correlation is applicable for a pure Al matrix and an Al matrix with the Si content up to 8 wt%, for fuel temperatures up to $200^{\circ}C$, and for Mo content in the range of 6 - 10wt%. In order to cover these ranges, in-pile data were included in modeling from various tests, such as the US RERTR-4, -5, -6, -7 and -9 tests and Korea's KOMO-4 test, that were designed to systematically examine the effects of the fission rate, temperature, Si content in Al matrix, and Mo content in U-Mo particles. A model converting the IL thickness to the IL volume fraction in the meat was also developed.

• Transactions of Materials Processing
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• v.12 no.2
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• pp.102-109
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• 2003

In the manufacturing process of metal matrix composites parts, thixoforging is one of the most effective forming processes. The major purpose of the current study is to provide the proper conditions such as the die shape, the forging velocity, the forging time, the forging pressure and reinforcement injection velocity and pressure on various defects in thixoforged cylinder liner, filling tests were performed by MAGMA S/W. In order to evaluate the effectiveness of the calculated conditions which is given by computer aided engineering, A357, A380 and SiC$_{p}$/A380 cylind~5$mu extrm{m}$r liner were fabricated under the calculated conditions. SiC$_{p}$/A380 composite billets were fabricated by both the mechanical stirring and electrical magnetic stirring process. Incase fo SiC$_{p}$/A380 composite cylinder liner, reinforcement distribution and effect of reinforcement(SiC$_{p}$) content(10~20 vol. %)and size(5.5~14${\mu}{\textrm}{m}$) on the mechanical properties were investigatedstigated.

• Journal of the Korean Ceramic Society
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• v.31 no.10
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• pp.1089-1098
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• 1994

The effect of Si3N4 addition on the microstructure and PTCR characteristics of BaTiO3 was studied. When 0.1 mol% Sb2O3-doped BaTiO3 codoped with Si3N4 (0.1, 0.25, 0.5, 0.75, and 1 wt%, respectively) were sintered, their microstructures were changed by the amount of the liquid phase as a result of eutectic reaction at 126$0^{\circ}C$. By these microstructural changes, the specific resistivity ratio($\rho$max/$\rho$min) with Si3N4 content variation of 0.1 mol% Sb2O3-doped BaTiO3 ceramics sintered at 130$0^{\circ}C$ for 1 hour varied between 3.70$\times$102(0.1 wt% Si3N4) to 1.16$\times$103 (1wt% Si3N4).

• Journal of the Korean institute of surface engineering
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• v.40 no.5
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• pp.214-218
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• 2007

The objective of this study is to evaluate the diffusion behavior of Al and Si from a coatings in the microstucture of Fe-Si steel. Steel samples deposited with Al-Si alloy are prepared by ion plating process, followed by annealing treatments for diffusion at $1050^{\circ}C$. Several intermetallic phases are found in the coatings and they are identified as Fe-Al and an orderd Fe-Si compounds. Series of different concentration profiles through the sample have been obtained and Si content reaches about 5 wt% in case of 90 minutes of diffusion time.

• Journal of Powder Materials
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• v.25 no.2
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• pp.144-150
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• 2018

$Al_2O_3-SiC$ ceramic composites are produced using pressureless sintering, and their plasma resistance, electrical resistance, and mechanical properties are evaluated to confirm their applicability as electrostatic-discharge-safe components for semiconductor devices. Through the addition of Mg and Y nitrate sintering aids, it is confirmed that even if SiC content exceeded 10%, complete densification is possible by pressureless sintering. By the uniform distribution of SiC, the total grain growth is suppressed to about $1{\mu}m$; thus an $Al_2O_3-SiC$ sintered body with a high strength over 600 MPa is obtained. The optimum amount of SiC to satisfy all the desired properties of electrostatic-discharge-safe ceramic components is obtained by finding the correlation between the plasma resistance and the electrical resistivity as a function of SiC amount.