• Journal of the Korean Electrochemical Society
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• v.15 no.3
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• pp.135-148
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• 2012

Ionic liquids are steadily attracting interests throughout a recent decade and their application is expanding into various fields including electrochemistry due to their unique properties such as non-volatility, inflammability, low toxicity, good ionic conductivity, wide electrochemical potential window and so on. These features make ionic liquids become an alternative solution for electrodeposition of metals that cannot be electroplated in aqueous electrolytes. In this review, we classify investigated metals into three categories, which are light (Li, Mg), refractory (Ti, Ta) and noble (Pd, Pt, Au) metals, rather than covering the exhaustive list of metals and try to update the recent development in this area. In electrodeposition of light metals, granular fine Li particles were successfully obtained while the passivation of electrodeposited Mg layers is an obstacle to reversible deposition-dissolution process of Mg. In the case of refractory metals, the quality of Ta and Ti deposit particles was effectively improved with addition of LiF and pyrrole, respectively. In noble metal category, EMIM TFSA ionic liquid as an electrolyte for Au electrodeposition was proven to be effective and BMP TFSA ionic liquid developed a smooth Pd deposit. Pt nanoparticle production from ionic liquid droplet in aqueous solution can be cost-effective and display an excellent electrocatalytic activity.

• Nuclear Engineering and Technology
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• v.54 no.6
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• pp.1954-1961
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• 2022

Lead-based fast reactor (LFR) has become one of the most promising reactors for Generation IV nuclear systems. A developing trend of LFR is high efficiency, along with operation temperatures up to 800 ℃ or even higher. One of key issues in the high-efficiency LFR is corrosion of cladding materials with lead at high temperatures. In this study, corrosion behavior of some refractory metals (Nb, Nb521, and Mo-0.5La) was investigated in static lead at 1000 ℃ for 1000 h. The results showed that Nb and Nb521 exhibited an intense dissolution corrosion with obvious lead penetration after corrosion, and lead penetration extended along the grain boundaries of the specimens. Furthermore, Nb521 showed a better corrosion resistance than that of Nb as a result of the elements of W and Mo included in Nb521. Mo-0.5La showed much better corrosion resistance than that of Nb and Nb521, and no lead penetration could be observed. However, an etched morphology appeared on the surface of Mo-0.5La, indicating the occurrence of corrosion to a certain degree. The results indicate that Mo-0.5La is compatible with lead up to 1000 ℃. While Nb and Nb alloys might be not compatible with lead for high-efficiency LFR at such high temperatures.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.325-330
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• 2001

Shizhuyuan W-Mo-Bi-Ca $F_2$polymetallic ore is classified to the refractory one due to its complex property, fine dissemination and close association of minerals. Through several years of researches, in line with GY new mineral processing technology developed by Guangzhou Research Institute of Nonferrous Metals, in sulfide flotation circuit, an iso-flotability flowsheet is used to replace original overall bulk flotation flowsheet, and in tungsten flotation circuit, a new chelating type-GY reagent and a special pulp-conditioning system and a new technology of wolframite slime flotation are used to replace the traditional "Caustic Soda Method"$_{［1］}$, the metallurgical performance is greatly improved. Besides, GY New Method has created a favorable condition for comprehensive recovery of fluoride from tungsten flotation tailings. Notable economic benefit has been achieved.d.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1323-1324
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• 2006

Refractory materials, such as W and Mo, are very useful elements for use in high-temperature applications. But it is not easy to fabricat pure W and Mo with very high density and retaining very fine grain size because of their high melting point. In this paper, a newly developed method named as resistance sintering under ultra high pressure was use to fabricate pure fine-grained W and Mo. The microstructure was analysis by SEM. The sintering mechanism is primary analyzed. Basic physical property of these sintered pure W and Mo, such as hardness, bend strength, are tested.

• Korean Journal of Materials Research
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• v.15 no.4
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• pp.217-223
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• 2005

Thermal, electrical and mechanical properties of high purity niobium and tantalum refractory rare metals were investigated tn evaluate the physical purity. Higher purity niobium and tantalum metals showed lower hardness due to smaller solution hardening effect. Temperature dependence of electrical resistivity showed a typical metallic behavior. Remarkable decrease in electrical resistivity was observed for a high purity specimen at low temperature. However, thermal conductivity increased for a high purity specimen, and abrupt increase in thermal conductivity was observed at very low temperature, indicating typical temperature dependence of thermal conductivity for high purity metals. It can be known that reduction of electron-phonon scattering leads to increase in thermal conductivity of high purity niobium and tantalum metals at low temperature.

• Korean Journal of Crystallography
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• v.5 no.1
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• pp.39-50
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• 1994

Diamond thin films were deposited on silicon, molybdebum, titanum and tugsten substrates, and were chlwntnizen using scanning electron microscopy, X-ray diffraction analysis and Raman spectroscopy. From the result of experiment in various deposition periods, it was found that found that were nucleated and grown on interlayed carbide layers, which were formed on refractory metal substrates at the initial stage of.

• Resources Recycling
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• v.18 no.4
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• pp.14-23
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• 2009

In terms of resources recycling and resolving waste disposal problems, it is very important to recover precious metals like Au, Ag and Pd and valuable metals like Cu, Sn and Ni from the scraps of waste electrical and electronic equipment(WEEE) that consists of detective electrical and electronic parts discarded during manufacturing electrical and electronic equipments and waste electrical and electronic parts generated during disassembling them. In general, the scraps of WEEE are composed of various metals and alloys as well as refractory oxides and plastic components. Precious and valuable metals from the scraps of WEEE can be recovered by gas-phase-volatilization, hydrometallurgical, or pyrometallurgical processes. However, the gas-phase-volatilization and hydrometallurgical processes have been suggested but not yet commercialized. At the present time, most of the commercial plants for recovering precious and valuable metals from the scraps of WEEE adopt pyrometallurgical processes. Therefore, in this paper, the technical and environmental aspects on the important pyrometallurgical processes through literature survey are reviewed, and the scale-up result of a new pyrometallurgical process for recovering the precious and valuable metals contained in the scraps of WEEE using waste copper slag is presented.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.89-92
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• 2009

As a class of materials, Ni-base superalloys are among the most difficult metal alloys to forge together with refractory metals and cobalt-base superalloys. The mechanical properties of Ni-base superalloys depend very much on grain size and the strengthening phases, $\gamma$' ($Ni_3$(Al,Ti)-type) and $\gamma$".($Ni_3$Nb-type). Especially, the control of grain size remains as a sole means for the control of mechanical properties. The grain size and distribution changes of the wrought superalloys during hot working and heat treatment are mainly controlled by the recrystallization and grain growth behaviors. In this presentation, prediction technology of grain size through the computer-aided process design, and numerical modeling for predicting the microstructure evolution of Ni-base superalloy during hot working were introduced. Also, some case studies were dealt with actual forming processes of Ni-base superalloys.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.946-947
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• 2006

Driven by the unavailibility of commercial test equipment for tensile and creep testing at temperatures up to $3000^{\circ}C$ a measuring system has been developed and constructed at the University of Applied Sciences, Jena. These temperatures are reached with precision by heating samples directly by electric current. Contact-less strain measurements are carried out with image processing software utilizing a CCD camera system. This paper covers results of creep tests which have been conducted on TZM sheet material (thickness 2 mm) in different heat-treatment conditions in the temperature range between $1200^{\circ}C$ and $1600^{\circ}C$.

• Journal of Ocean Engineering and Technology
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• v.13 no.1 s.31
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• pp.70-78
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• 1999

오늘날 기계공업 현장에서 심공드릴가공은 광범위한 응용과 양호한 생산성으로 인하여 그 요구가 증가 되고 있다. 그러므로, 본 연구는 난삭재인 SKD11고합금공구강을 여러가지 절삭조건하에서 BTA드릴가공하여 얻은 실험결과(표면조도, 진직도, 진원도, 원통도, 구멍확대량, 등)를 다루었으며 이들의 이론적 배경과 실험을 비교 분석하였다. 프레스금형 부품과 기계부품으로 사용되고 있는 SKD11고합금공구강은 기계가공이 힘든 난삭재료로서 그 어려움이 크므로 본 연구는 생산현장에 보다 나은 심공드릴가공결과와 관련 지식을 제공 할수 있다고 사료된다.