• Journal of the Semiconductor & Display Technology
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• v.2 no.1
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• pp.21-24
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• 2003

Sludged silicon powders that are generated during silicon ingot slicing process have potential usage as silicon source in fabricating silicon carbide powders by adding carbon. A thermodynamic calculation is performed to consider a plausible formation condition for the silicon carbide powders. A thin silicon oxide layer around silicon powder is sufficient to supply equilibrium oxygen partial pressure at the formation temperature($1400^{\circ}C$) of the silicon carbide in the Si-C-O ternary system. Formation of silicon carbide by using the sludged silicon powders is more efficient than by using silicon oxide powders.

• Resources Recycling
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• v.31 no.5
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• pp.52-58
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• 2022

Silicon carbide powder was prepared from carbon black and silicon recovered from waste solar panels. In the solar power generation market, the number of crystalline silicon modules exceeds 90%. As the expiration date of a photovoltaic module arrives, the development of technology for recovering and utilizing silicon is very important from an environmental and economic point of view. In this study, silicon was recovered as silicon carbide from waste solar panels: 99.99% silicon powder was recovered through purification from a 95.74% purity waste silicon wafer. To examine the synthesis characteristics of SiC powder, purified 99.99% silicon powder and carbon powder were mixed and heat-treated (1,300, 1,400 and 1,500 ℃) in an Ar atmosphere. The characteristics of silicon and silicon carbide powders were analyzed using particle size distribution analyzer, XRD, SEM, ICP, FT-IR, and Raman analysis.

• Journal of the Korean Ceramic Society
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• v.51 no.6
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• pp.539-543
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• 2014

Foam type porous silicon carbide ceramics were fabricated by a polymer replica method using polyurethane foam, carbon black, phenol resin, and silicon powder as raw materials. The influence of the C/Si mole ratio of the ceramic slurry and heat treatment temperature on the porous silicon carbide microstructure was investigated. To characterize the microstructure of porous silicon carbide ceramics, BET, bulk density, X-ray Powder Diffraction (XRD), and Scanning Electron Microscope (SEM) analyses were employed. The results revealed that the surface area of the porous silicon carbide ceramics decreases with increased heat treatment temperature and carbon content at the $2^{nd}$ heat treatment stage. The addition of carbon to the ceramic slurry, which was composed of phenol resin and silicon powder, enhanced the direct carbonization reaction of silicon. This is ascribed to a consequent decrease of the wetting angles of carbon to silicon with increasing heat treatment temperature.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1091-1092
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• 2006

Silicon nitride - silicon carbide composite was developed by using an abrasive SiC powders as a raw material. The composites were prepared by mixing abrasive SiC powder with silicon, pressing and sintering at $1400^{\circ}C$ under nitrogen atmosphere in atmosphere controlled vacuum furnace. The proportion of silicon in the initial mixtures varied from 20 to 50 wt%. After sintering, crystalline phases and microstructure were characterized. All composites consisted of ${\alpha}-Si_3N_4$ and ${\beta}-Si_3N_4$ as the bonding phases in SiC matrix. Their physical and mechanical properties were also determined. It was found that the density of the obtained composites increased with an increase in the $Si_3N_4$ content formed in the reaction.

• Journal of the Korean Ceramic Society
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• v.43 no.6 s.289
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• pp.327-332
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• 2006

The effect of the processing parameters on the sintered density and strength of silica-bonded SiC (SBSC) ceramics was investigated for three types of batches with different particle sizes. The SBSC ceramics were fabricated by an oxidation-bonding process. The process involves the sintering of powder compacts in air so that the SiC particles bond to each other by oxidation-derived $SiO_2$ glass or cristobalite. A finding of this study was that a higher flexural strength was obtained when the starting powder was smaller. When a ${\sim}0.3_{-{\mu}m}$ SiC powder was used as a starting powder, a high strength of $257{\pm}42\;MPa$ was achieved at a relative density of ${\sim}80%$.

• Carbon letters
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• v.15 no.3
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• pp.180-186
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• 2014

This study highlights a novel method and mechanism for the rapid and effective milling of carbon fibers (CFs) in silicon carbide (SiC) powder, and also the dispersion of CFs in SiC powder. The composite powders were prepared by chopping and exfoliation of CFs, and ball milling of CFs and SiC powder in isopropyl alcohol. A wide range of CFs loading, from 10 to 50 vol%, was studied. The milling of CFs and SiC powder was checked by measuring the average particle size of the composite powders. The dispersivity of CFs in SiC powder was checked through scanning electron microscope. The results show that the usage of exfoliated CF tows resulted in a rapid and effective milling of CFs and SiC powder. The results further show an excellent dispersion of CFs in SiC powder for all CFs loading without any dispersing agent.

• Journal of the Microelectronics and Packaging Society
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• v.10 no.3
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• pp.67-71
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• 2003

Sawing silicon ingot with abrasive slurry generates sludge that includes abrasive powders, cutting oil, and silicon powders. The abrasive powders and cutting oil are being separated and reused. Mixing the remained stodged silicon powders with carbon powders and subsequent heat-treatment are conducted to produce silicon carbide. The size of SiC whiskers and powders was smaller than the conventionally grown silicon carbide whiskers that were synthesized by adding micron-size metal impurities. Impurity related mechanism is attributed to the formation of the silicon carbide whiskers, as metal impurities are contained in the stodged silicon powders.

• Journal of the Korean Ceramic Society
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• v.53 no.1
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• pp.99-104
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• 2016

High purity Si-C (99.999%) powder prepared by mechanical alloying was added to a commercial SiC powder as a sintering additive. Reaction bonded silicon carbide balls and jars with high purity (99.98%) were used for the mechanical alloying. As a result, the purity of the sintered Si-C was higher than 99.99%. When sintered at $2200^{\circ}C$ under 50 MPa pressure for 1 h, SiC containing 10 wt% of high purity Si-C showed a relative density of 95.3%, similar to the relative density of commercial SiC (95%). However, the relative density of SiC decreased to 90.6% without the additive when the applied pressure decreased to 40 MPa. In contrast, the relative density was nearly unaffected by the decrease of the pressure when using the Si-C additive. Therefore, the addition of Si-C powder promoted the densification of SiC above $2000^{\circ}C$ under 40 MPa pressure.

• Journal of Powder Materials
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• v.25 no.5
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• pp.402-407
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• 2018

Molybdenum silicide has gained interest for high temperature structural applications. However, poor fracture toughness at room temperatures and low creep resistance at elevated temperatures have hindered its practical applications. This study uses a novel powder metallurgical approach applied to uniformly mixed molybdenum silicide-based composites with silicon carbide. The degree of powder mixing with different ball milling time is also demonstrated by Voronoi diagrams. Core-shell composite powder with Mo nanoparticles as the shell and ${\beta}-SiC$ as the core is prepared via chemical vapor transport. Using this prepared core-shell composite powder, the molybdenum silicide-based composites with uniformly dispersed ${\beta}-SiC$ are fabricated using pressureless sintering. The relative density of the specimens sintered at $1500^{\circ}C$ for 10 h is 97.1%, which is similar to pressure sintering owing to improved sinterability using Mo nanoparticles.

• Journal of the Korean Ceramic Society
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• v.48 no.5
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• pp.360-367
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• 2011

Macroporous silicon carbide (SiC) ceramics were fabricated by powder processing and polymer processing using carbon-filled polysiloxane as a precursor. The effects of the starting SiC polytype, template type, and template content on porosity and flexural strength of macroporous SiC ceramics were investigated. The ${\beta}$-SiC powder as a starting material or a filler led to higher porosity than ${\alpha}$-SiC powder, owing to the impingement of growing ${\alpha}$-SiC grains, which were transformed from ${\beta}$-SiC during sintering. Typical flexural strength of powder-processed macroporous SiC ceramics fabricated from ${\alpha}$-SiC starting powder and polymer microbeads was 127 MPa at 29% porosity. In contrast, that of polymer-processed macroporous SiC ceramics fabricated from carbon-filled polysiloxane, ${\beta}$-SiC fillers, and hollow microspheres was 116MPa at 29% porosity. The combination of ${\alpha}$-SiC starting powder and a fairly large amount (10 wt%) of $Al_2O_3-Y_2O_3$ additives led to macroporous SiC ceramics with excellent flexural strength.