• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.368-368
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• 2011

최근에 보고된 양질의 고효율Cu(In,Ga)Se2 (CIGS) 태양전지는 CIGS광흡수층이 강한 (220:204) 우선배향성을 갖는 것으로 알려져 있다 [1]. 이러한 CIGS우선배향성은 Se 증착압력, Na농도, 기판온도 및 Mo후면전극의 표면상태에 영향을 받는 것으로 알려져 있지만 정확한 상호관계는 아직 명확히 알려져 있지 않으며, 특히 Mo후면전극의 영향에 대해서는 체계적인 연구결과조차 극히 드문 상황이다 [2]. 본 연구에서는 CIGS 박막의 우선배향성에 대해 Mo후면전극의 미세구조가 미치는 영향 및 이에 따른 cell특성의 변화에 대해서 연구하였다. Mo후면전극의 미세구조는 2 mTorr~16 mTorr까지 증착압력을 변화시켜 제어되었고, CIGS광흡수층은 이렇게 준비된 Mo후면전극상에 3단계 동시증밥법(3-stage process)을 사용하여 형성하였다. XRD를 통한 박막의 우선배향성 평가에서, Mo 증착압력에 대한 IGS I(300)/I(006) 및 CIGS I(220:204)/I(112)의 거동은 Mo 미세구조와 밀접한 관련이 있는 잔류응력(residual stress)의 변화 거동과 상당히 일치함을 보였다. 이에 반해, 높은 압력의 Mo위에 형성된 강한 (220:204) 우선배향성의 CIGS와 bare-glass위에서 형성된 강한 (112) 우선배향성의 CIGS내 Na농도는 서로 유사하였다. 상기의 결과는 Mo미세구조 그 자체가 CIGS 박막 우선배향성의 원인이 됨을 나타낸다. Selenized Mo시편의 XRD분석 및 IGS/Mo 시편의 TEM분석결과을 통해 MoSe2의 반응성이 잔류응력과 비례하는 Mo in-gain 밀도에 의존하는 함을 알 수 있었고, 이러한 MoSe2반응성(reactivity)과 IGS우선배향성 사이에 상당히 밀접한 관련이 있으며 이에 CIGS의 우선배향성이 결정됨을 확인하였다. 마지막으로, Mo변수에 의해 제작된 cell의 특성분석으로부터 cell의 효율이 주로 VOC의 증가에 기인하여 CIGS (220:204) 우선배향성의 정도에 비례하였다.

• Nano
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• v.13 no.12
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• pp.1850144.1-1850144.13
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• 2018

A nano-$MoS_2$/montmorillonite K-10 (K10) composite was prepared and characterized. The composite contains two types of 2H-$MoS_2$ nanoparticles. One is the hollow spherical $MoS_2$ with a size range of 75 nm, and the other is the spherical nano cluster of $MoS_2$ with a size range of 30 nm. The two kinds of nano-$MoS_2$ were formed via assembly of numerous $MoS_2$ nano-platelets with a size of ~10 nm. A tribological comparison was then made among nano-$MoS_2$/K10, K10, nano-$MoS_2$ and a mechanical mixture of K10 and nano-$MoS_2$. K10 reduced the wear but slightly increased the friction. Nano-$MoS_2$ remarkably reduced both friction and wear. The mechanical mixture demonstrated better wear resistance than nano-$MoS_2$, indicating a synergistic anti-wear effect of nano-$MoS_2$ and K10. The synergistic effect was reinforced using nano-$MoS_2$/K10 instead of the mechanical mixture. A part of the $MoS_2$ in the contact region always lubricated the friction pair, and the rest formed a tribofilm. K10 segregated the friction pair to alleviate the ablation wear but magnified the abrasive wear. S-$MoS_2$ protects K10 and they together function as both a lubricant and an isolating agent to reduce the ablation and abrasive wear.

• Resources Recycling
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• v.20 no.4
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• pp.71-77
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• 2011

$MoO_3$ powders were reduced to $MoO_2$ under Ar+$H_2$ gas mixture in a tubular furnace at temperature range 723~873 K. Reaction rate was quantitatively deduced by measuring relative humidity of off gas. Observed reaction rate increased significantly with hydrogen partial pressure and reaction temperature and the rate of $H_2O$ evolution increased drastically during the initial period of reduction. As reduction proceeded, however, $H_2O$ partial pressure decreased noticeably. During the initial period of the reduction, a linear relationship for time dependence of the reduction fraction was observed. The activation energy for the reduction of $MoO_3$ to $MoO_2$was 73.56 kJ/mol during the initial period of reduction.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1988.06a
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• pp.31-38
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• 1988

최근, 유체윤활영역에 있어서 될수 있는 한 점성저항을 감소시키기 위해서 윤활유의 저점도화가 진행되고 있는 실정이다. 그러나 윤활유의 저점도화로 인한 문제점으로써 금속-금속간 접식부가 증가하게 된다. 금속간 접식이 증가함에 따라 마찰저항이 커지게 되며, 이와 같은 마찰저항의 증대를 방지하기 위하여 마찰조정제(FM)가 자동차 엔진유를 비롯한 각종 윤활유에 첨가되어지고 있다. 또한 윤활유의 사용조건이 가곡(고온, 고가중) 해짐에 따라 첨가제의 다기능성이 요구되고 있는 가운데, 이와 같은 요구를 만족시켜 주기 위한 연구가 진행되고 있다. 최근에 와서 유용성 유기모리브덴계 화합물이 마찰,마모 및 산화방지제로서 주목받고 있다. 마찰, 마모을 감소시키기 위한 목적으로 널리 사용되고 있는 $MoS_2$는 고체윤활제로서 각광을 받고 있지만, 실제사용상의 문제로서 입자의 크기, 분산상의 문제 및 분산제와의 반응으로 인하여 마찰, 마모를 증대시키므로 역효과를 가져 오기도 한다. $MoS_2$와 같은 고체윤활제의 분상상의 무제점을 보완한 유용성 모리브덴계 화합물은 마찰, 마모 및 산화방지제로서 자동차 엔진유를 비롯하여 각종 윤활유에 첨가되고는 있지만 메카니즘에 대해서는 거의 해명되고 있지 않는 현실정이다. 본 연구는 유용성 유기모리브덴계 화합물중의 Molybdenum dialkyl dithiophosphate (MoDTP)의 마찰감소작용을 해명하기 위해서, MoDTP 첨가제의 마찰시험 및 마찰표면의 분석을 통하여 MoDTP의 마찰감소작용의 메카니즘을 명확하게 함을 자적으로 하고 있다.

• Journal of the Korean Chemical Society
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• v.34 no.2
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• pp.171-178
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• 1990

The rates of the reaction Of $[MoO_2(S_2CNC_4H_8)_2]$ with triphenylphosphine in 1,2-dichloroethane have been by the spectrophotometric method. The increase in absorbance at 514 nm has been interpreted as a result of production of $[Mo_2O_3(S_2CNC_4H_8)_4]$ and the decrease in absorbance then corresponds to the reduction of $[Mo_2O_3(S_2CNC_4H_8)_4]$. The data suggest mechanisms involving the formation of $\mu$-oxo dimer in the first stage and molybdenum(IV) in the second stage.

• Journal of Korea Foundry Society
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• v.16 no.2
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• pp.141-148
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• 1996

In high chromium cast iron, the control of matrix microstructure as well as carbide structure is important to the performance as a wear resistant material. In this study, 3.0% C-24.0% Cr white cast irons with various molybdenum contents(residual, 1.0%, 3.0% and 5.0%) were solidified conventionally and unidirectionally for studying their effects on the microstructure and hardness. In the conventional casting, two sets of castings were poured from each melt. One set of the castings consisted of cylindrical bars of 10 and 20mm by 155mm long. The second set of the castings was a cylindrical bar of 30mm by 200mm long. On the other hand, a pep-set mold set on the Cu plate was employed to make the solidification unidirectionally. X-ray diffraction method was used to observe retained austenite and carbides in the high chromium cast iron. The morphology of eutectic $M_7C_3$ carbides changed from needle-like type to nodular type with the increase of Mo content. And, the presence of $M_2C$ carbides was identified in the sample where Mo was added over 3.0 %. Primary and eutectic carbides appeared as rod type and corngrain type, respectively in the unidirectionally solidified samples which were cut to parallel to the solidification direction. In the EDX analysis, Cr concentration was higher in the primary and eutectic $M_7C_3$ carbides, Mo in the $M_2C$ carbides, and Fe in the matrix.

• Korean Journal of Materials Research
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• v.11 no.9
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• pp.763-768
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• 2001

Molybdenum-based thermal spray powder is widely used for coating the moving parts of the internal combustion engines due to its excellent wear resistance. A composite powder of the $Mo_{40}(Al_{1-x}Si_x)_{60}$ system was synthesized using the SHS method. The synthesized bulk was pulverized and specially treated to produce thermal spray powder. It was found that the synthesis reaction consisted of two-steps: the formation of $Al_8/Mo_3$ and the formation of Mo(Al,Si)$_2$. Both the temperature and the rate of the SHS reaction linearly increased with the increase of the value of x in $Mo_{40}(Al_{1-x}Si_x)_{60}$, The temperature and the rate of the reaction were also affected by the compacting density of the specimens, exhibiting the maximum valves at 62% and 60%, respectively. Since spherical shape is advantageous to the thermal spraying process, shape-control of the powder was attempted with PVA as a binding additive, resulting in the successful production of almost perfectly spherical powder of 80 $\mu\textrm{m}$ Ø$(d_{50})$ mean particle size.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.12
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• pp.607-613
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• 2001

Molybdenum thin films were deposited on the soda lime glass(SLG) substrates by direct-current planar magnetron sputtering, with a sputtering power density of $4.44W/cm^2$. The working pressure was varied from 0.5 mtorr to 20 mtorr to gain a better understanding of the effect of sputtering pressure on the morphology and microstructure of the Mo film. Thin films of $CU(InGa)Se_2$ (CIGS) were deposited on the Mo-coated glass by three stage co-evaporation process. The highest efficiency device was obtained at the maximum value of the tensive stress. The morphology of Mo-coated films were examined by using scanning electron microscopy The film's microstructure, such as the preferred orientation, the full width at half-maximum(FWHM), and the residual intrinsic stress were examined by X-ray diffraction.

• Korean Journal of Metals and Materials
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• v.50 no.8
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• pp.549-556
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• 2012

The tribological behavior of CrMoN films with respect to surface chemistry was investigated by using X-ray photoelectron spectroscopy (XPS). All of the films were prepared from a hybrid PVD system consisting of DC unbalanced magnetron (UBM) sputtering and arc ion plating (AIP) sources. The tribological property of the films was evaluated by a friction coefficient using a Ball-on-disk type tribometer. The chemistry of wear track was analyzed by energy dispersive spectroscopy (EDS) and XPS. The friction coefficient was measured to be 0.4 for the CrMoN film, which is lower than that of a monolithic CrN film. EDS and XPS results imply the formation of an oxide layer on the coating surface, which was identified as molybdenum oxide phases, known to be a solid lubricant during the wear test.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.5 no.6
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• pp.558-561
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• 2004

The morphology of silica supported $MoO_{3}$ catalysts, which was prepared by impregnation of ammonium heptamolybdate(AHM) with various surface loadings up to 4 atoms $Mo/nm^{2}$, was studied using x-ray diffraction(XRD). All morphologies of silica supported $MoO_{3}$ appear to be thermodynamically driven. For high loaded catalysts there appeared three states: a sintered and well-dispersed hexagonal state at moderate temperature calcination($300^{\circ}C$), and a sintered orthorhombic state at high temperature calcination($500^{\circ}C$). Whereas the sintered orthorhombic phase is detected by XRD at loadings in excess of 1.1 atom $Mo/nm^{2}$, the well-dispersed hexagonal phase is not detected even until 4.0 $atomsMo/nm^{2}$. The higher apparent dispersion of the hexagonal phase may arise from some role of ammonia which results in a stronger $MoO_{3}-SiO_{2}$ surface interaction.