• 한국수소및신에너지학회논문집
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• 제10권2호
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• pp.101-106
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• 1999

Hydrogen solubility in internally oxidized Pd-Mo(Al) alloys has been studied at 323 K from the measurements of pressure-composition(p-c) isotherms. Internal oxidation of $Pd_{0.985}Al_{0.015}$ and $Pd_{0.97}Mo_{0.03}$ alloys results in the precipitation of Al and Mo particles in a matrix of pure Pd. It has been observed that the presence of the aluminum and molybdenum oxide precipitates results in an enhanced hydrogen solubility in the dilute phase region of Pd-H in a Pd/aluminum(molybdenum)oxide composites. Hydrogen solubility enhancements due to the presence of residual stresses around ceramic particles have been observed from p-c isotherms determined at 323 K after oxidation at 1073 K. The solubility enhancements in completely internally oxidized alloys are greater than that in partially oxidized alloys. The stress fields near the ceramic precipitates are the major source of the solubility enhancements. Transmission electron microscopy indicates that alumina precipitates are nanometer-sized and coherent with the Pd matrix after oxidation.

• Design & Manufacturing
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• 제11권3호
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• pp.8-12
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• 2017

In general, metallic bio-materials is more widely used in solid tissue like bone or tooth than flexible tissue such as skin or muscle. Especially, Cobalt Chrome Molybdenum(Co-Cr-Mo), which is used in tooth surgery, has a great corrosion resistance. Because this bio-material is non-toxic in human body, and has a bio-compatibility that the vital reaction is not occurred with tissue in body. However the chemical reaction is occurred by fatal matter that deteriorate the property of material surface in conventional polishing, and it can affect to fatal disease in human body or decrease the material properties such as hardness, yield strength or bio-compatibility. This surface in poor condition can cause development of corrosion or bacteria. In this study, MR fluid polishing is used to minimize the scratch, pit or surface flaws generated in conventional polishing. Surface roughness is measured according to the polishing condition to obtain fine surface condition.

• Nuclear Engineering and Technology
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• 제54권2호
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• pp.709-731
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• 2022

Loss of fracture resistance due to thermal aging degradation is a potential limiting factor affecting the long-term (80+ year) viability of nuclear reactors. To evaluate the effects of decades of aging in a practical time frame, accelerated aging must be employed prior to mechanical characterization. In this study, a variety of chemically and microstructurally diverse austenitic stainless steels were aged between 0 and 30,000 h at 290-400 ℃ to simulate 0-80+ years of operation. Over 600 static fracture tests were carried out between room temperature and 400 ℃. The results presented include selected J-R curves of each material as well as K_0.2mm fracture toughness values mapped against aging condition and ferrite content in order to display any trends related to those variables. Results regarding differences in processing, optimal ferrite content under light aging, and the relationship between test temperature and Mo content were observed. Overall, it was found that both the ferrite volume fraction and molybdenum content had significant effects on thermal degradation susceptibility. It was determined that materials with >25 vol% ferrite are unlikely to be viable for 80 years, particularly if they have high Mo contents (>2 wt%), while materials less than 15 vol% ferrite are viable regardless of Mo content.

• Current Photovoltaic Research
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• 제5권4호
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• pp.145-149
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• 2017

Transition metal dichalcogenides (TMDs) have attracted much attention because of their excellent optical and electrical properties, which are the applications of next generation photoelectric devices. In this study, $MoS_2$, which is a representative material of TMDs, was formed by magnetic sputtering method and surface changes and optical characteristics were changed with thickness variation. In addition, by implementing the photodetector of $MoS_2/p-Si$ structure, it was confirmed that the change of the electrical properties rather than the change of the optical properties according to the thickness change of $MoS_2$ affects the photoresponse ratio of the photodetector. This result can be used to fabricate effective photoelectric devices using $MoS_2$.

• 대한화학회지
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• 제39권6호
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• pp.446-452
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• 1995

전기화학적으로 리튬이온을 $FeMoO_4Cl$ 격자내에 층간삽입시킨 $Li_xFeMoO_4Cl$ 화합물은 X-선 회절분석 및 정전류 방전 실험 결과 $1{\leq}X{\leq}2$ 영역에서 단사정계로 결정화되었다. X-선 광전자 분광분석 연구결과, $0{\leq}X{\leq}1$ 영역에서는 리튬이온의 층간삽입시 Fe(III) 이온이 Fe(II) 이온으로 환원되었으며 이때 결정구조는 정방정계에서 단사정계로 전이되었다. 반면, $1{\leq}X{\leq}2$ 영역에서는 Mo(VI) 이온이 낮은 산화상태로 환원되었고, 결정계 전이나 Fe(II) 이온의 환원은 관찰되지 않았다. Mo의 3d X-선 광전자 스펙트럼을 가우스함수를 이용하여 deconvolution한 결과, Mo(VI), Mo(V) 및 Mo(IV)에 해당하는 세 종류의 피크를 분리해 낼 수 있었다. 이와 같이 Mo가 혼합 원자가 상태로 존재하는 이유는 리튬이 층간삽입됨에 따라 생성된 Mo(V)의 일부가 Mo(IV)와 Mo(VI)로 disproportionation되기 때문이다.

• 대한화학회지
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• 제31권6호
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• pp.520-526
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• 1987

피리디니움 옥소이소치오시안네이토 몰리브데이트(V)와 아민 카르복실기를 가진 이미노디아세틱액시드 유도체를 반응시켜 아민 카르복실기를 가진 디옥소-디-뉴우-옥소-디몰리브데이트(V) 착물을 합성하였다. 이들에 대한 원소분석, 스펙트라의 해석 그리고 전기전도도의 측정으로 부터 착물의 성질과 그 구조를 추정하였다. 적외선 스펙트라에서 $Mo=O_t$ 신축진동에 기인한 두 개의 흡수띠가 900~$980cm^{-1}$ 영역에서 관찰되었으며, $MoO_2Mo$의 비대칭신축진동 및 대칭신축진동은 720~$750cm^{-1}$, 440~$485cm^{-1}$ 에서 각각 나타났었고, 카르복실기와 금속결합간의 비대칭 신축진동이 1585~$1,640cm^{-1}$에서 흡수띠가 관찰되었다. 전자흡수스펙트럼 결과 $^2B_2{\to}^2B_1$의 결정장 전이는 24,800∼$28,000cm^{-1}$, 전하이동 전이는 32,500~$33,800cm^{-1}$, 42,000~$47,500cm^{-1}$에서 각각 나타났다. 이들 착물은 노란색 혹은 오렌지색이며 반자성체 물질이였다.

• 대한화학회지
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• 제34권5호
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• pp.452-459
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• 1990

일련의 산소 및 황 가교결합의 이핵 몰리브덴(V) 착물, Mo$_2$O$_4$L$_2$, Mo$_2$O$_3$L$_4$, Mo$_2$O$_2$S$_2$L$_2$, 그리고 Mo$_2$OS$_3$L$_2$, L = bis(hydroxyethyl)dithiocarbamate을 합성하였다. 말단과 가교의 산소결합 착물은 수용액에서 (PyH)$_2$MoOCl$_5$ 혹은 MoCl$_5$와 리간드의 반응으로부터 합성되었고, Mo$_2$O$_4^{2+}$핵에서 산소가 황으로 치환된 착물, Mo$_2$O$_2$S$_2$L$_2$은 Mo$_2$OS$_3$L$_2$의 클로로포름 용액에 트리페닐포스핀을 가하므로 합성되었다. 한편, Mo$_2$OS$_3$L$_2$착물은 sodium dithionite 존재하에서 (NH$_4$)$_2$MoS$_4$와 리간드의 수용액으로부터 얻어졌다. 합성한 착물에 대한 원소분석과 ir, uv-vis, nmr, 그리고 mass 스펙트라에 의한 착물의 분광학적 성질을 조사하였다. 또한 디메틸술폭시드 용액에서 이들 착물의 전기화학적 성질을 순환전압-전류법으로 조사하였다.

• 전기화학회지
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• 제2권3호
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• pp.150-155
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• 1999

[ $H_2-O_2$ ] 알칼리형 연료전지용 수소극으로서 아크융해법으로 제조된 Brewer-Engel type의 Co-Mo$(35\;wt\%)$ 및 Ni-Mo$(35\;wt\%)$ 금속간화합물 전극의 전기화학적 안정성이 조사되었다. $N_2$가스로 용존산소를 제거한 $80^{\circ}C$ 6N KOH 전해질 내에서 금속간화합물 전극의 전기화학적 안정성에 미치는 전해질의 농도 및 온도의 영향이 조사되었다. 또한, AFC의 정상 작동조건하에서는 Co-Mo및 Ni-Mo전극의 전기화학적 안정성에 대한 분극전압(과전압)의 영향이 논의되었다. Co-Mo전극은 Ni-Mo전극에 비하여 낮은 전기화학적 안정성을 보였다. 수소가스 평형전위로부터 낮은 양분극 과전압 하에서 Co-Mo전극에서는 Co와 Mo의 용해가 동시에 일어났다. 그러나, Co는 Mo에 비하여 급격히 용해되었다 높은 양분극 과전압에서는 전극표면에 $Co(OH)_2$ 부동태 피막이 형성되었다. Ni-Mo전극의 경우에는 Mo의 용해반응이 치밀한 $Ni(OH)_2$, 부동태 피막형성에 의하여 억제되어 우수한 전기화학적 안정성을 보였다.

• Tribology and Lubricants
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• 제5권1호
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• pp.12-20
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• 1989

The friction and wear behavior of molybdenum disulfide filled polymer composites sliding against metal has been investigated using pin-on-disc machine and microscope. The observed wear rates were reduced by the addition of MoS$_2$ to nylon and this can be attributed to the homogenous transfer of MoS$_2$ to the counteddace thereby modifying sliding conditions. The friction of filled and unfilled nylon was increased with increasing sliding speed, and the catastropic wear rate was occurred at high normal load. This have been explained by thermal degradation. In the case of HDPE, however, the wear rate was not always reduced by the addition of MoS$_2$ and the influence of MoS$_2$ was mainly even the opposite. Filled and unfilled HDPE had lower values of friction and wear rate than those of nylon. Micrographs appeared that the delamination of the worn surface in nylon/MoS$_2$ composite occurred and revealed that the worn surface of HDPE presented a number of characteristic features as wear grooves, pulls, and smears and crescents.

• Elastomers and Composites
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• 제55권4호
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• pp.339-346
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• 2020

We functionalized a wear-resistant carbon-based MoS2 filler to solve its limited wear condition problem. The filler exhibits excellent lubricative properties. The surface modification of MoS2 was carried out using a (3-glycidyloxypropyl)trimethoxysilane (GPTMS) silane coupling agent to improve the low compatibility and dispersibility of the filler that generally degrade the performance of composites. A silane coupling agent was employed for the functionalization of MoS2, and its effect on the wear resistance of MoS2/Polyamide-6,6 was investigated. The silanization of MoS2 was identified by contact angle analysis and Fourier-transform infrared, energy dispersive X-ray, and X-ray photoelectron spectroscopies. The wear resistance of the composite was found to be improved significantly by the surface functionalization of MoS2.