• Membrane and Water Treatment
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• v.9 no.1
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• pp.63-68
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• 2018

Molecular dynamics simulations were used to study the removal of Cd(II) as a heavy metal from wastewater using armchair carbon nanotube, boron nitride nanotube and silicon carbide nanotubes under applied electric field. The system contains an aqueous solution of $CdCl_2$ as a heavy metal and a (7,7) nanotube as a nanostructured membrane, embedded in a silicon nitride membrane. An external electric field was applied to the considered system for the removal of $Cd^{2+}$ through nanotubes. The simulation results show that in the same conditions, considered armchair nanotubes were capable to remove $Cd^{2+}$ from wastewater with different ratios. Our results reveal that the removal of heavy metals ions through armchair carbon, boron nitride and silicon carbide nanotubes was attributed to the applied electric field. The selective removal phenomenon is explained with the calculation of potential of mean force. Therefore, the investigated systems can be recommended as a model for the water treatment.

• Transactions of Materials Processing
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• v.29 no.2
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• pp.97-102
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• 2020

Wire drawing is a metalworking process used to reduce the cross-section of a wire by pulling the wire through multi-stage drawing dies. The aim of this study is to fabricate a drawing wire using 2 stage drawing process. The finite element analysis of wire drawing was conducted to validate the efficiency of the designed process and the experiment was performed to validate the designed wire drawing process using 2 stage tungsten carbide die. Dry lubricant with powder was applied for producing a wire of desired diameter. Finally, a drawing wire using 2 stage die for cold rolling mill was developed.

• The Korean Journal of Ceramics
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• v.4 no.3
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• pp.171-175
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• 1998

$Al_2O_3$-TiC composites were prepared from aluminum, titanium oxide, and carbon fibers by self-propagating high-temperature synthesis(SHS). After the SHS reaction, the TiC phase in the sample was found either fibrous or non-fibrous shape. The fraction of the fibrous TiC phase varied with the amount of $Al_2O_3$ diluent addition. The optimum amount of diluent to make fibrous carbide was determined to be 30%. The fibers were hollow inside and made of multiple grains with a composition of titanium carbide. The hollow fiber formation mechanism was suggested and discussed. The synthesized powders were consolidated to dense composites by hot pressing at $1750^{\circ}C$ under 30 MPa.

• 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 ${\sim}80%$.

• Journal of the Korean institute of surface engineering
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• v.24 no.1
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• pp.8-8
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• 1991

To investigate the effects of substrate on transverse-rupture strength(TRS) and bonding strength between substrate and TiC layer coated by CVD, two kinds of substrate (substrate A:WC-9.5wt%Co-MC*[low C], substrate B: WC-6wt% Co-MC*[high C] were studied in terms of Cobalt and C contents respectively. For preparation of test samples the coating parameters of deposition time, deposition temperature and deposition pressure were varied. The result show that the carbon contents in substrates have greater effects on the TRS of the CVD TiC coated cemented carbide than Co contents in substrates.

• Journal of the Korean Society for Heat Treatment
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• v.10 no.4
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• pp.219-231
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• 1997

Inconel alloys used as nuclear power plant components have experienced intergranular stress corrosion cracking problems inspite of their good corrosion characteristics. In order to investigate the effects of heat treatments on carbide precipitation and intergranular stress corrosion cracking(IGSCC) in Inconel alloys, DSC(Differential Scanning Calorimeter), TEM, EDXS and static potential corrosion tests were carried out. Thermal treatment at $750^{\circ}C$ for 15hours in Inconel alloys increased the density of intergranular carbide. The carbides are mainly $Cr_7C_3$ in Inconel 600, and $Cr_{23}C_6$ in Inconel 690. The Cr depletion around grain boundary is not crucial factor on IGSCC. The carbides in grain boundary play an important role as acting dislocation source, and as decreasing stress around growing crack.

• 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.53 no.6
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• pp.581-596
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• 2016

A comprehensive review on sliding and solid particle erosion wear characteristics of silicon carbide (SiC) ceramics and SiC composites is provided. Sliding or erosion wear behavior of ceramics is dependent on various material characteristics as well as test parameters. Effects of microstructural and mechanical properties of SiC ceramics are particularly focused to understand tribological performance of SiC ceramics. Results obtained between varieties of pairs of SiC ceramics indicate complexity in understanding dominant mechanisms of material removal. Wear mechanisms during sliding are mainly divided in two groups as mechanical and tribochemical. In solid particle erosion conditions, wear mechanisms of SiC ceramics are explained by elastic-plastic deformation controlled micro-fracture on the surface followed by radial-lateral crack propagation beneath the plastic zone.

• Journal of the Korean Ceramic Society
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• v.40 no.9
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• pp.832-836
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• 2003

Multi-layer ceramic composites were prepared by tape casting followed by hot pressing using silicon nitride layer with silicon nitride whiskers, silicon nitride layer with silicon carbide particles and boron nitride-alumina layer. The whiskers were aligned during the casting. As the whisker content of the silicon nitride layer was increased up to 10 wt％, the flexural strength of the multi-layer composite was increased. However, further increase of the whisker content in the layer resulted in a rapid decrease of the strength of the composite. The results suggest that the strength of multi-layer ceramic composite showing non-catastrophic failure behavior can be significantly improved by incorporating the aligned whiskers in the layers.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.362-363
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• 2006

Nano-structured tungsten carbide compacts with cobalt matrices (WC-Co) offer new opportunities for achieving superior hardness and toughness combinations. A unified modeling and simulation tool has been developed to produce maps of sintering pathways from nanocrystalline WC powder to sintered nano-structured WC-Co compacts. This tool includes (1) die compaction, (2) grain growth, (3) densification, (4) sensitivity analysis, and (5) optimization. All material parameters were obtained by curve fitting based on results with two WC-Co powders. Critical processing parameters are determined based on sensitivity analysis and are optimized to minimize grain size with high density.