• 한국표면공학회지
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• 제30권6호
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• pp.374-381
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• 1997

We have studied the effect of the interface between tungsten silicide and polysilicon the silicide reaction. The results showed that the cleaning of the silicon surface prior to the deposition of tungsten silicide affected the interface properties, thereby leading to the difference in the resistivity and surface morhpology of tungsten silicide. Compared with HF cleaning, the use of SCl cleaning yielded higher resistivity of tungsten silicide at the low anneal temperature (up to $900^{\circ}C$). However, furtherature to $1000^{\circ}C$ reduced the resistivity significantly, similar to that obtained with HF cleaning. It was also observed that the annealing of WSix/HF-cleaned poly-si allowed the formation of bucking weve (partially decohesion area) on the surface. In contrast, the use of SCl celaning did not produce the buckling waves on the surface. Also the presence of 200$\AA$ -thick TiW between tungsten silicide and HF-cleaned poly-Si effectively prevented the formation of the waves. However, high-temperature annealing of WSix/200A-TiW/Poly-Si allowed the excess silicon in tungsten silicide to precipitate inside the silcide, causing the slight increase of the resistivity after annealing at $1050^{\circ}C$.

• 한국생산제조학회지
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• 제19권3호
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• pp.370-375
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• 2010

본 연구에서는 전해가공을 이용해서 직경이 균일한 텅스텐 카바이드 미세축을 제작하는 실험을 수행하였다. 전해가공을 통해 미세축으로 사용 가능한 형상을 얻기 위한 최적의 가공 조건에 대해 고찰하였다 이 과정에서 미세축의 형상에 영향을 주는 여러 인자들을 적절하게 조절하여 최적의 형상을 얻을 수 있었다. 그리고 가공된 미세축을 이용하여 적절한 조건으로 2차, 3차 가공을 수행하여 초미세축을 가공할 수 있음을 보였다. 그리하여 실험 결과 직경 $30{\mu}m$, 길이 $500{\mu}m$의 텅스텐 카바이드 미세축을 제작하였다.

• 자원리싸이클링
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• 제27권6호
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• pp.3-10
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• 2018

텅스텐은 고융점금속으로 주로 초경합금으로 사용되고 있다. 알칼리용액에서 텅스텐은 $WO{_4}^{2-}$로 존재하는데 용액의 pH가 감소함에 따라 중합반응이 일어나며 텅스텐산으로 침전된다. 따라서 원광석 및 2차 자원으로부터 텅스텐 회수를 위한 습식 제련 기술은 산침출과 알칼리침출로 대별된다. 2차 자원에 함유된 금속의 종류와 함유량 및 텅스텐의 소재화를 고려해서 2차 자원으로부터 텅스텐을 고순도로 회수하기 위한 공정을 선택해야 한다.

• Nuclear Engineering and Technology
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• 제51권2호
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• pp.495-500
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• 2019

When a new fuel is developed, various mechanical properties are absolutely necessary for a safety analysis of the fuel for the licensing and prediction of its mechanical behavior during operation and accident conditions. In this paper, a mechanically equivalent surrogate plate of U-Mo dispersion fuel is presented using tungsten, substitute material of U-Mo particle. A surrogate plate, composed of tungsten/aluminum dispersion meat and aluminum alloy cladding, is manufactured with the same fabrication process with that of fuel plate except that a tungsten powder is used instead of U-Mo powder. A modal test showed that the surrogate plate and fuel plate have similar dynamic characteristics, and a tensile test demonstrated the similarity of the material property up to the yield strength range. The conducted tests proved that the surrogate tungsten plate has equivalent mechanical behaviors with that of a fuel plate, which leads to the acceptable use of a surrogate fuel assembly using tungsten/aluminum dispersion meat in various mechanical tests. The surrogate fuel assembly can be utilized for various out-of-pile characteristic tests, which are necessary for the licensing achievement of a research reactor that uses U-Mo dispersion fuel as a driver.

• 한국산업융합학회 논문집
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• 제24권3호
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• pp.283-288
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• 2021

A tungsten material using a pressure sintering process and a titanium sintering additive was prepared to evaluate the microstructure, and mechanical properties of flexural strength and hardness. In addition, the reliability on each hardness data was evaluated by analyzing the distribution of the hardness of the tungsten material using the Weibull probability distribution. In particular, the optimal manufacturing conditions were analyzed by analyzing the correlation between the sintering temperature and the mechanical properties of the tungsten sintered body. Although the sintering density of the tungsten material was hardly changed up to 1700 ℃, but it was increased at 1800 ℃. The hardness of the tungsten sintered material increased as the sintering temperature increased, and in particular, the tungsten material sintered at 1800 ℃ showed a high hardness value of about 1790 Hv. It showed relatively excellent flexural strength at a sintering temperature of 1800 ℃.

• 한국분말재료학회지
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• 제29권1호
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• pp.47-55
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• 2022

Tungsten carbide is widely used in carbide tools. However, its production process generates a significant number of end-of-life products and by-products. Therefore, it is necessary to develop efficient recycling methods and investigate the remanufacturing of tungsten carbide using recycled materials. Herein, we have recovered 99.9% of the tungsten in cemented carbide hard scrap as tungsten oxide via an alkali leaching process. Subsequently, using the recovered tungsten oxide as a starting material, tungsten carbide has been produced by employing a self-propagating high-temperature synthesis (SHS) method. SHS is advantageous as it reduces the reaction time and is energy-efficient. Tungsten carbide with a carbon content of 6.18 wt % and a particle size of 116 nm has been successfully synthesized by optimizing the SHS process parameters, pulverization, and mixing. In this study, a series of processes for the high-efficiency recycling and quality improvement of tungsten-based materials have been developed.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1993년도 추계학술대회 논문집
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• pp.120-123
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• 1993

This paper describes the deposition and characteristics of electrochromic tungsten oxide thin films for electrochromic smart windows. Tungsten Oxide thin films(WO$_3$) are deposited by thermal evaporation techniques. By varying deposition parameters, WO$_3$ thin films exhibit different optical properties. The electrochromic devices are consist of ITO glass/ WO$_3$ thin films/ LiClO$_4$-propylene carbonate electrolyte/ counter electrode. The electrochromic properties of tungsten oxide thin films with different deposition condition ale investigated.

• Journal of Information Display
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• 제10권1호
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• pp.45-48
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• 2009

The ionization of a helium atom was investigated as a function of gas pressure, with the use of a tungsten tip. The tungsten tip, to which the external voltage was applied, was used to generate a constant electron current. The ionization current of helium gas was measured as a function of gas pressure. Effective ionization occurred in the pressure range of 0.5-20 torr when the distance between the field emission tip and the collector was 1 cm. The ionization current was linearly proportional to the voltage that was applied to the tungsten tip.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2002년도 춘계학술대회 논문집
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• pp.187-190
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• 2002

To study adiabatic shear band formation of tungsten heavy alloys, 5 prismatic specimens are loaded by high velocity impacts and treated as plane strain problems. Their volume percent of tungsten particles in WHA are 81%, 93% and 97% respectively and for the fixed 81% volume percent, small size particle model, large size particle model, undulated particle models are considered and then, the effects of particle's volume ratio, geometry and size to the formation of shear band are discussed.

• 대한방사선치료학회지
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• 제14권1호
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• pp.89-94
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• 2002

I. 목적 : Sebaceous gland carcinoma, Squamouse cell ca., basal cell ca., low grade MALToma 등에서 전자선을 이용하여 eyelid 치료시 안구의 선량은 될 수 있는 한 최소선량으로 관리되어야 한다. 그러나 upper나 lower eyelid 전부를 포함하는 조사면은 치료후 백내장등의 심각한 부작용을 만들어 낼 수 있다. 본원에서는 상용되는 Tungsten eyeball shielding block과 기존의 lead block에 의한 차폐시 안구의 선량을 비교하여 Tungsten eyeball shielding block의 유용성에 대해 평가해 보고자한다. 2. 재료 및 방법: 시판되고 있는 BOLX-I 물질을 이용하여 모형안구를 제작하고 안구의 6곳 주요지점을 선정한 후 TLD chip을 이용하여 주로 사용되는 6MeV와 9MeV electron beam의 선량을 측정, Tungsten eyeball shielding block과 lead block의 선량을 비교하였다. 3. 결과 : Tungsten eyeball shielding block의 사용이 안구의 주요 지점인 각막, 망막, 시신경부위의 선량을 lead block사용 때보다 $90\%$에서 $50\%$의 감소효과가 있었다. 4. 결론 : Tungsten eyeball shielding block은 6MeV 전자선 치료시 보다 뛰어난 차폐효과를 보여 임상에서의 유용성이 인정되었다. 그러나 안구에 삽입시 환자의 고통과 불쾌감을 줄일 수 있는 방안이 모색되어야 하는 숙제를 남겼다.