• Journal of Powder Materials
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• v.12 no.3
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• pp.174-178
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• 2005

This paper deals with the fabrication of titanium carbide using fine titanium hydride. The ratio of $TiH_2$ and C (Activated carbon) was 1:1 (mol) and milled in a planetary ball mill at a ball-to-powder weight ratio of 20:1. Thereafter, TGA was performed at $1400^{\circ}C$ to observe change of weight with milling time. Titanium carbide was obtained by using tempering the milled powders at $1100-1500^{\circ}C$. The microstructures of titanium carbide as well as the change of the lattice parameters and particle size have been studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM).

• Journal of the Korean Society for Heat Treatment
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• v.12 no.1
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• pp.21-30
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• 1999

The present study were investigated changes of precipitation behaviour of laves phase in ferrite single phase and ferrite-martensite dual phase and precipitation of laves phase under stress. Hardness changes in ferrite phase appeared two hardness peaks by precipitation of initial fine precipitator and laves phase in 3Mo-0.3Si and 3Mo-0.3Si-C specimens, respectively. Hardness changes in martensite phase of 3Mo-0.3Si-C specimen was lower in the initial stage of aging by carbide precipitation and after this, increased by re-hardening due to precipitation of laves phase. In the ferrite phase, laves phase was mainly precipitated, whereas in the martensite phase, carbide was preferentially formed during the initial stage of aging and with increasing aging time, laves phase and carbide were simultaneously precipitated by precipitation of laves phase at around carbide. In the ferrite-martensite interface, laves phase was mainly precipitated and carbide was mainly formed at boundary of lath martensite than grain boundary. Adding the stress in aging, fine precipitator of inital precipitation of laves phase precipitated in (100) of perpendicular to tensile direction and has grown to only followed<010>direction and also, volume fraction of laves phase increased. Consequently, the stress added was accelerated initial precipitation of laves phase.

• Journal of Welding and Joining
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• v.34 no.6
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• pp.55-61
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• 2016

Recently developed ferritic heat resistance steel, T24 was used to evaluate microstructure characteristics of simulated heat affected zone. Also, correlation between the prior austenite grain size and amount of $M_{23}C_6$ carbide dissolution was discussed. With the increasing of peak temperature, Grain size steadily increased up to $1050^{\circ}C$ and then rapidly increased at $1150^{\circ}C$. Of the peak temperature $950{\sim}1050^{\circ}C$, amounts of $M_{23}C_6$carbide dissolution are low. But Most of $M_{23}C_6$ carbide that is inhibited grain growth were dissolved above $1050^{\circ}C$ and decreased volume fraction of carbide. This indicates that grain growth may be achieved through dissolution of carbide in the base material. As of welding, due to very rapid heating rate, $M_{23}C_6$ carbide exists above equilibrium solution temperature that is $800^{\circ}C$, even at $1050^{\circ}C$. So, It was confirmed that close correlation between carbide dissolution in the base material and grain growth. Calculated grain size has a linear relationship with peak temperature, on the other hand, measured grain size discontinuously increased between $950{\sim}1050^{\circ}C$ and above $1050^{\circ}C$. Grain size of heat affected zone at $1350^{\circ}C$ peak temperature showed maximum 67um and minimum 4um. Also, The number of side showed 3 to 10.

• Journal of Photoscience
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• v.12 no.3
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• pp.171-174
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• 2005

The relationship between porous surfaces and photoluminescence (PL) behavior of porous silicon carbide (PSC) in various solvents has been studied. The porous surfaces of p-type silicon carbide can be fabricated by electrochemical anodization from the 6H, 15R, 4H-${\alpha}$-SiC substrates in dark-current mode (DCM) condition. We have been investigated the dependence of the PL spectra of PSC under the medium having the different dielectric constants. It has been found that PL depends sensitively on the environment surrounding the surface. The extent of chemically stability on the surface of PSC due to the various solvents was confirmed by reflectance Fourier transform infrared (FTIR) spectroscopy. Detailed IR experiments on the PSC samples were carried out before and after various solvents immersion. These results will be offered important information on the origin of PL in porous structure.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.887-888
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• 2006

The present study describes the wear and mechanical behaviour of carbide composites in cyclic loading applications (blanking of sheet metal). Adhesive wear as well as fatigue endurance were tested, complemented by XRD studies. It was found that the blanking performance of a carbide composite is controlled by its resistance to adhesion wear and fatigue sensitivity. XRD studies revealed that fatigue damage is preceded by plastic strain in both phases of the composites

• Journal of the Korean Society for Heat Treatment
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• v.30 no.2
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• pp.43-52
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• 2017

Heat treatment condition for dissolution of the M23C6 carbides in 2.25Cr-1Mo-V-Ti material for thermal power plant tube was investigated using a dilatometer method. 2.25Cr-1Mo-V-Ti material was heat-treated at $900{\sim}1,100^{\circ}C$ for 0, 10, 30 min to find the proper dissolution condition of M23C6 carbides. The phase identification and volume fraction of the carbide were measured by using OM, SEM, EBSD and TEM analysis. Optimal heat treatment condition of M23C6 carbide dissolution was selected by predicting dissolution temperature of carbide using Bs points appeared at dilatometer curve. Experimental results showed that the conditions of carbide dissolution was 900, 1,000, $1,100^{\circ}C$ for 30 min. Eventually, the optimal heat treatment condition for dissolution was 30 min at $1,000^{\circ}C$ considering the minimum coarsening of Austenite grain size.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2003.11a
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• pp.78-84
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• 2003

Boron carbide thin coatings were deposited on silicon wafers by DC magnetron sputtering using a $B_4C$ target with As as processing gas. Various amounts of methane gas $(CH_4)$ were added in the deposition process to better understand their influence on tribological properties of the coatings. Reciprocating wear tests employing an oscillating friction wear tester were performed to investigate the tribological behaviors of the coatings in ambient environment. The chemical characteristics of the coatings and worn surfaces were studied using X-ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES). It revealed that $CH_4$ addition to As processing gas strongly affected the tribologcal properties of sputtered boron carbide coating. The coefficient of friction was reduced approximately from 0.4 to 0.1, and wear resistance was improved considerably by increasing the ratio of $CH_4$, gas component from 0 to $1.2\;vol\;\%$. By adding a sufficient amount of $CH_4\;(1.2\%)$ in the deposition process, the boron carbide coating exhibited lowest friction and highest wear resistance.

• Journal of Power System Engineering
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• v.17 no.4
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• pp.103-108
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• 2013

This study was investigated the effect of austenitizing treatment the microstructure and mechanical properties in modified 440A steel, and the results were as follows. The amount of remaining carbide decreases with increasing the austenitizing treatment temperature, and all carbide is completely dissolved at $1250^{\circ}C$. The amount of remaining carbide decreases with increasing the austenitizing treatment time, but the carbide remains insoluble up to 120 minutes at $1050^{\circ}C$. The strength and hardness gradually decrease with increasing the austenitizing treatment temperature and is significantly lower at $1250^{\circ}C$, while the elongation and the impact value rapidly increase. The strength and hardness rapidly decrease, the elongation and impact value rapidly insrease with increasing the austenitizing treatment time and exhibit no change at above 120 minutes. The austenitizing treatment modified 440A steel is required for temperature of above $1050^{\circ}C$ and time of above 60 minutes.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.4 no.3
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• pp.12-24
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• 1995

Various surface grinding experiments using resin bonded diamond abrasive wheels are carried out for tungsten carbide materials in order to minimize the damage on the ground surface and to purse the precise dimension compared to conventional grinding machine. When grinding quality is constant, theoretical grinding effect is changed according to the speed of workpiece. Accordingly, grinding forces, which are Fn, Ft, were analyzed for the machining processes of tungsten-carbide material to obtain optimum grinding conditions. Brief investigation is carried out to decrease the dressing efficiency of resinoid bonded diamond grinding wheel to grind tungsten-carbide. Truing is also carried out to provide a desired shape on a wheel or to correct a dulled profile. High quality in dimensional accuracy and surface are often required as a structural components, therefore 3-points bending test is carried out to check machining damage on the ground surface layer, which in one of sintered brittle material. From this experimental study, some useful machining data and information to determine proper machining condition for grinding of tungsten-carbide materials are obtained.

• Journal of Powder Materials
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• v.10 no.6
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• pp.390-394
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• 2003

Ultra fine titanium carbide particles were synthesized by novel metallic thermo-reduction process. The vaporized TiC1$_4$+$CCl_4$ gases were reacted with liquid magnesium and the fine titanium carbide particles were then produced by combining the released titanium and carbon atoms. The vacuum treatment was followed to remove the residual phases of MgC1$_2$ and excess Mg. The stoichiometry, microstructure, fixed and carbon contents and lattice parameter were investigated in titanium carbide powders produced in various reaction parameters.