• Composites Research
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• v.15 no.3
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• pp.1-10
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• 2002

The effect of size of SiC particles and additive Mg content on the mechanical properties and wear characteristics were investigated for the SiCp/AC8A composites fabricated by pressureless infiltration process. Results showed that the hardness and the bending strength increased with decreasing the size of SiC particle. By increasing the Mg content the hardness of SiCp/AC8A composites increased due to the hard reaction products, however the bending strength decreased by formation of coarse precipitates and high porosity level. The SiCp/AC8A composites exhibited about 6 times higher wear resistance compared with AC8A alloy at high sliding velocity and as increasing the particle size, wear resistance was improved. The major wear mechanical of SiCp/AC8A composites exhibited the abrasive wear at low to high sliding velocity whereas AC8A alloy showed adhesive and melt wear at high sliding velocity.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.6
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• pp.383-388
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• 2019

High purity SiC fine powder with metal impurity contents of less than 1 ppm was synthesized by improved carbothermal reduction process, and the synthesized powder was used for SiC single crystal growth in RF heating PVT device at temperature above 2,100℃. In-situ x-ray image analyzer was used to observe the sublimation of the powder and single crystal growth behavior during the growth process. SiC powder was used as a source of single crystal growth, exhausted from the outside of the graphite crucible at the growth temperature and left graphite residues. During the growth, the flow of raw materials was concentrated in the middle and influenced the growth behavior of SiC single crystals. This is due to the difference in temperature distribution inside the crucible due to the fine powder. After the single crystal growth was completed, the single crystal ingot was cut into a 1 mm thick single crystal substrate and finely polished using a diamond abrasive slurry. A dark yellow 4H-SiC was observed overall of single crystal substrate, and the polycrystals generated in the outer part may be caused by the incorporation of impurities such as the bubble layer mixed in the process of attaching the seed crystal to the seed holder.

• Journal of Korea Foundry Society
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• v.14 no.5
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• pp.471-479
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• 1994

Al-2%Si-2%Mg alloy containing SiC particle in 20, $70{\mu}m$ were prepared by mean of squeeze casting with various pressure 50, 100, 150 and 220MPa respectively. The specimens were made by casting into $50{\Phi}{\times}100{\ell}$ mold under various squeeze conditions(pressures, pressurizing temperature, particle sizes). Mechanical properties(hardness, tensile strength, elongation and wear characteristics) were evaluated at room temperature with those various fabrication factors. It became feasible to make favorable Al-SiCp composite free from casting defects by the injection of Ar gas during melting and 100MPa pressure squeeze casting. However, pressure of 50MPa was not sufficient to avoid completely porosity formation as a result of precessing and shrinkage during solidification. As the particle size is smaller and the squeeze pressure is higher, the hardness and tensile strength at room temperature are higher. Cell size became smaller gradually with increase of squeeze pressure. With increase of squeeze pressure(MPa), wear behaviors of those composites were changed from adhesive into abrasive wear, and the tendency of above behavior became outstanding with increasing sliding speed. The chemical reaction(4Al＋3SiC${\rightarrow}$$Al_4C_3+3Si$) is more accelerated at interface between SiCp and matrix with increase of squeeze pressure. Therefore $Al_4C_3$ intercompound and Si peak intensity is increased at interface.

• Journal of the Korean institute of surface engineering
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• v.28 no.4
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• pp.225-235
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• 1995

To investigate the effects of pretreatment and substrate bias on the characteristics of the diamond thin films, the thin films were deposited on the p-type Si(100) wafer by MPECVD using mixtures of $H_2$, $CH_4$, and $O_2$ gases. Deposition was carried out at the substrate temperature of $900^{\circ}C$ and at the pressure of 40torr. The effect of the pretreatment on the film formation was the examined by using SiC and diamond powders as abrasive powders. Furthermore, the substrate bias effect on the formation of the diamond film was also examined. The highest nucleation density was observed for the pretreatment with 40~60$\mu\textrm{m}$ size of diamond powders and a negative bias potential(-50V). Many defects and(111) twins in the diamond films were observed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1992.10a
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• pp.131-135
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• 1992

랩핑은 가공물의 치수정도와 다듬질면 정도의 향상을 위해 최종적으로 사용되는 가공법이다. 랩제(abrasive)로 서는 다이아몬드, SiC, 그리고 $Al_{2}$ $O_{3}$ 등이 사용되며 공작액과 혼합되어 가공물과 랩핑 블럭 사이에 끼이어 연삭작용을 하게 된다. 본 연구에서는 중요 가공변수등이 가공면 거칠기와 가공율에 미치는 영향을 실험측정하였고, 그 실험결과를 세라믹 랩핑가공의 기본적 연삭작용 기구인 취성파괴.현상을 기초로 하여 설명하였다.

• Korean Journal of Materials Research
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• v.16 no.12
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• pp.766-770
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• 2006

The frictional behavior of oxide films on top of the plasma nitrocarburized compound layers was investigated in terms of post-oxidation treatment temperatures. The post-oxidation treatment at both temperatures($400^{\circ}C,\;500^{\circ}C$) produced magnetite($Fe_3O_4$) films which led to a significant enhancement in corrosion resistance. However, this process did not result in any improvement in frictional behavior of the nitrocarburized surface. The wear mechanisms were governed predominantly by the abrasive action of the slider on the surface irrespective of the counterface material(SiC and Bearing steel). When the specimen was sliding against a SiC counterface, the oxide films were destroyed during the early stage of the sliding process and the wear debris of the oxide film at the sliding track had a great influence on the friction coefficient. On the other hand, when sliding against a bearing steel counterface, the slider was mainly worn out due to the much higher hardness of the surface hardened layer. The fluctuation of the friction coefficient of $400^{\circ}C$-oxidized/ nitrocarburized specimen is much severer than that of $500^{\circ}C$ specimen, due to the less amount of wear debris.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.25 no.1
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• pp.27-31
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• 2015

The degradation of refractories can be caused by erosion, friction of abrasive particles, as well as by corrosion by molten slag in the gasification reactors. There was little knowledge about the erosion of refractories so far. The castable refractories of which the maximum applying temperature of 1300 and $1500^{\circ}C$ were abraded using SiC particles varying the incidence angles. It was revealed that the maximum abrasion was occurred at the incidence angle of $60{\sim}75^{\circ}$ not at $90^{\circ}$ and thought that the porosity of the refractories was the principle factor.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2000.06a
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• pp.166-172
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• 2000

Friction characteristics of phenolic resin-based friction composites containing threedifferent relative amounts of graphite and zirconium silicate were investigated by using a pad-on-disk type friction tester. Constant temperature test and constant interval test at three different initial temperatures(100. 200, 300$^{\circ}C$) were performed to examine the effects of friction heat on friction characteristics at elevated temperature. The friction composite(FMO.7) with higher content of ZrSiO$_4$showed unstable friction force at higher temperature and resulted in larger fluctuations of vibration during friction test. The abrasive action of ZrSiO$_4$in friction composite impeded stable transfer film and induced higher friction heat at friction interface. Friction oscillations according to the temperature were associated with the formation of transfer film(i'd body layer) on the friction composite and the counter part.

• Journal of the Semiconductor & Display Technology
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• v.10 no.3
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• pp.35-42
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• 2011

This paper describes the characteristics of high speed grinding and the influence of wheel surface speed V and a grindability of the grinding materials. The various fine ceramics pieces was ground by metal and vitrified bonded diamond wheel. The surface roughness of fine ceramics(Zirconia($ZrO_2$), Silicon Carbide(SiC), Silicon Nitride($Si_3N_4$), Alumina($Al_2O_3$)) decreases from $0.05{\mu}m(R_{max})$ to $0.025{\mu}m(R_{max})$ when the wheel speed at grinding point increases the wheel speed. Relation between the temperature at grinding point and surface roughness was linear. Abrasive jet machining(AJM), a specialized from of shot blasting, is considered one of the most helpful micro machining methods for hard and brittle materials such as glasses and ceramics by constant pressure grinding.

• Tribology and Lubricants
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• v.20 no.3
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• pp.125-131
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• 2004

Nano-wear behavior of amorphous carbon films was studied by Atomic Force Microscopy. The a-C films are deposited on Si(100) substrate by DC magnetron sputtering method. The influences of different surface roughness on the nano-wear are investigated. Nano-wear tests were carried out using a very sharp diamond coated tip. Its spring constant was 1.6 N/m and radius of curvature was 110 nm. Normal force used in the wear tests ranged 0 to 400 nN. It was found that surface depression occurred during scratching because of plastic deformation and abrasive wear (cutting St ploughing). Wear depth increased linearly with normal force. Changing the surface roughness variables according to the bias pulse control, the less surface roughness decreased the wear depth. The thickness did not affect the wear resistance.