• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.2
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• pp.57-62
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• 2007

The lubricational characteristics about friction wear has an effect on the material quality of surface. In this paper, we studied the lubricational characteristics through the surface modification experiment by spray coating the surface with $MoS_{2}$ and PTFE solid lubricants. In the case of $MoS_{2}$ and PTFE coating, the friction coefficient of Journal is lower than that for noncoating so the friction characteristics is excellent. In particular, the beginning characteristics of $MoS_{2}$ coating is excellent, and in the case of PTFE coating, seizure dose not appear seizure. $MoS_{2}$ and PTFE coating are excellent in the extreme pressure at high load. The wear characteristics is excellent in the following order; PTFE < $MoS_{2}$ < Non Coating. For Non coating, seizure appears at the beginning due to the heat, but in the case of $MoS_{2}$ and PTFE coating, it will have the excellent heat stability even at high temperature.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1997.10a
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• pp.93-99
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• 1997

High Temperature wear behavior of plasma sprayed ZrO$_2$ and MoS$_2$, $Fe_2O_3$ coatings were investigated for high temperature wear resistance applications. The MoS$_2$, $Fe_2O_3$ added powders containing 2.5, 5.0, 7.5, 10.0 mol% of $MoS_2$, $Fe_2O_3$ for plasma spray were made by spray drying method. Wear test were performed at temperature ranges from room temperature to 600$\circ$C. The microstructural change of coatings and the worn. surface were examined by SEM and XRD. In ZrO$_2$ coating, the coefficient of friction and wear amount of room temperature to 400$\circ$C was increased with temperature and decreased with temperature over 400$\circ$C. The coefficient of friction and wear amount of MoS$_2$ added coatings were increased with temperature, but those of $Fe_2O_3$ added coatings had lower coefficient of friction and higher wear resistance than ZrO$_2$ coating.

• Journal of Surface Science and Engineering
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• v.39 no.2
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• pp.70-75
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• 2006

As technology advances, there is a demand for development of hard, solid lubricant coating. (Ti,Cr)N-$MoS_2$, films were deposited on SKD 11 tool steel substrate by co-deposition of $MoS_2$, with (Ti,Cr)N using a D.C. magnetron sputtering process. The influence of the $N_2/Ar$ gas ratio, the deposition temperature, the amount of $MoS_2$ in the films, and the bias voltage on the mechanical and the structural properties of the films were investigated. Wear tests were performed on the films deposited in various conditions.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.7
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• pp.417-422
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• 2017

A high-performing photoelectric device was realized for the $MoS_2$-embedded Si device. $MoS_2$-coating was performed by an available large-scale sputtering method. The $MoS_2$-layer coating on the p-Si spontaneously provides the rectifying current flow with a significant rectifying ratio of 617. Moreover, the highly optical transmittance of the $MoS_2$-layer provides over 80% transmittance for broad wavelengths. The $MoS_2$-embedded Si photodetector shows the sensitive photo-response for middle and long-wavelength photons due to the functional $MoS_2$-layer, which resolves the conventional limit of Si for long wavelength detection. The functional design of $MoS_2$-layer would provide a promising route for enhanced photoelectric devices, including photovoltaic cells and photodetectors.

• Corrosion Science and Technology
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• v.23 no.1
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• pp.72-81
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• 2024

The Ti-6Al-4V alloy is widely used as an implant material due to its higher fatigue strength and strengthto-weight ratio compared to pure titanium, excellent corrosion resistance, and bone-like properties that promote osseointegration. For rapid osseointegration, the adhesion between the titanium surface and cellular biomolecules is crucial because adhesion, morphology, function, and proliferation are influenced by surface characteristics. Polymeric peptides and similar coating technologies have limited effectiveness, prompting a demand for alternative materials. There is growing interest in 2D nanomaterials, such as MoS₂, for good corrosion resistance and antibacterial, and bioactive properties. However, to coat MoS₂ thin films onto titanium, typically a low-temperature hydrothermal synthesis method is required, resulting in the synthesis of films with a toxic 1T@2H crystalline structure. In this study, through high-temperature annealing, we transformed them into a non-toxic 2H structure. The implant coating technique proposed in this study has good corrosion resistance and biocompatibility, and antibacterial properties.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.05a
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• pp.160-161
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• 2015

탄소 원자들이 육각형의 벌집 모양으로 배열된 그래핀은 강철보다 200배 이상 강하며, 다이아몬드보다 2배 이상 열전도율이 높으며, 구리보다 100배 이상 전기가 잘 통하며, 실리콘보다 100배 이상 전자가 빠르게 움직일 수 있는 장점이 있다. 그래핀의 이러한 기계적, 열적, 전기적 특성은 에너지 밴드 갭이 없는 그래핀의 전자구조에서 근거하고 있다. 그러나 이러한 에너지 밴드 갭이 없는 그래핀은 반도체가 아닌 준금속의 특성을 보이며, 전자산업의 핵심소자인 트랜지스터로의 상용화에 큰 장벽이 되고 있다. 이러한 그래핀의 단점을 보완하고자 그래핀 이외의 2D 물질에 주목하기 시작하였으며, 그 가운데 최근 $MoS_2$과 같은 Transiton-Metal dichalcogenide(TMD)에 대한 관심이 급증하고 있다. TMD 중 대표적인 물질인 MoS2는 단일 층이 직접 전이 밴드 갭을 가진 반도체로서 전자회로와 발광 다이오드에 이용될 잠재적 가능성을 가진 재료이다. 본 연구에서는 이러한 MoS2 박막 형성을 하기 위해서 대면적이고 저비용으로 만들 수 있는 spin coating을 이용하려고 한다. spin coating을 이용하여 박막을 얻기 위해서는 좋은 wettability가 필수적이므로 이를 개선하기 위하여 용액, 전처리에 따른 wettability를 비교한 후, 열처리를 하여 그 표면을 관찰하고 Raman spectroscopy를 이용하여 분석하여 최적의 조건을 찾기 위한 실험을 하였다.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1998.10a
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• pp.265-271
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• 1998

High temperature wear behavior of plasma sprayed zirconia based coating sealing with zirconia sol were investigated for high temperature wear resistance application. The zirconia powders containing 2.5, 5.0, 7.5, 10.0 mol% of MoS$_2$, $Fe_2O_3$ for plasma spray were made by spray drying method. As-sprayed coating was sealed by zirconia-sol to fill up the pore and crack in coating. wear test were performed at temperature ranges from room temperature to 600$\circ$C. The microstructural changes of before and after sealing process were examined by SEM, XRD and EPMA. After sealing process, the porosity was decreased and micro-hardness was increased. The wear properties of coating after sealing process were improved by sealing of pores and cracks. The behavior of wear amount and coefficient of friction were same tendency to before sealing process.

• Journal of Surface Science and Engineering
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• v.39 no.6
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• pp.263-267
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• 2006

As technology advances, there is a demand for development of hard solid lubricant coating. (Ti, Cr, Zr)N-$MoS_2$ films were deposited on AISI H13 tool steel substrate by co-deposition of $MoS_2$ with (Ti, Cr, Zr)N using a D.C. magnetron sputtering process. The influence of the $N_2Ar$ gas ratio, the amount of $MoS_2$ in the films and the bias voltage on the mechanical and structural properties of the films were investigated. The highest hardness level was observed at the $N_2/Ar$ gas ratio of 0.3. Hardness of the films did not change much with the increase of the $MoS_2$ content in the films. As the substrate bias potential was increased, hardness level of the film reached maximum at -150 V. Surface morphology of these films indicated that high hardness was attributed to the fine dome structure.

• Membrane Journal
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• v.28 no.3
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• pp.180-186
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• 2018

The nano-composite membranes were prepared onto the polyvinylidene fluoride (PVDF) hollow fiber membranes through twice dip-coating known layer-by-layer method. For the first coating, poly(vinylsulfonic acid, sodium salt)(PVSA) and Poly(styrene sulfonic acid)(PSSA) were used with varying the concentration and ionic strength (IS) and the poly(ethyleneimine)(PEI) as the second coating material was fixed at 10,000 ppm and IS = 0.3. To characterize the prepared nano-composite membranes, the permeabilities and rejection ratio were measured for each 100 ppm NaCl, $CaSO_4$, $MgCl_2$, and 25 ppm MO aqueous solution. The rejections were increased as the concentrations of coating materials increased. And it was confirmed that the salt rejections for PSSA as the coating material were higher than for PVSA. Typically, the permeability, 1.848 LMH and the rejection for MO 76.3% were obtained at the coating conditions of PSSA 30,000 ppm and I.S = 1.0.

• Nuclear Engineering and Technology
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• v.55 no.5
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• pp.1855-1862
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• 2023

Graphite crucibles are used for melting uranium and its alloys in VIM furnace. Various coating materials namely Al₂O₃, ZrO₂, MgO etc. are applied on the inner surface of the crucibles using paint brush or thermal spray technique to mitigate U-C interaction. These leads to significant amount of carbon pick-up in uranium. In this study, the attempts are made to develop multilayer coatings comprising of SiC/Y₂O₃ and Mo/Y₂O₃ on graphite to study the feasibility of minimizing U-C interaction. The parameters are optimized to prepare SiC coating of about 70㎛ thickness using CVD technique on graphite coupons and subsequently Y₂O₃ coating of about 250㎛ thickness using plasma spray technique. Molybdenum and Y₂O₃ layers were deposited using plasma spray technique with 70㎛ and 250㎛ thickness, respectively. Interaction studies of the coated graphite with molten uranium at 1450℃ for 20 min revealed that Y₂O₃ coating with SiC interlayer provides physical barrier for uranium-graphite interaction, however, this led to the physical separation of coating layer. Y₂O₃ coating with Mo interlayer provided superior barrier effect showing no degradation and the coatings remained intact after interaction tests. Therefore, the Mo/Y₂O₃ coating was found to be a promising solution for minimizing carbon pick-up during uranium/uranium alloy melting.