• 제목/요약/키워드: Fluorides

검색결과 81건 처리시간 0.022초

불화물계 용융염중에서 Steel 기지 소재의 Al 전해피복에 관한 연구 (A Study on Metalliding of Al on Steel from Molten Fluorides)

  • 이민구;서길원;백영현
    • 한국표면공학회지
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    • 제26권4호
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    • pp.183-191
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    • 1993
  • Diffusion coating(metalliding) of aluminium on steel from molten fluorides(29.2wt.% LiF-11.7wt.% NaF-59.1wt.% KF, FLINAK) was studied. The electrolytic cell consists of a steel cathode and a consumable aluminium anode. Effects of manganese on the aluminium deposition were also investigated. The quality of the deposit was analyzed by SEM, OM, EPMA, EDXA, and also examined by means of Micro-Vickers hardness and corrosion tests. Deposit layer was identified as an aluminium-rich iron alloy caused by diffusion process. The optimum condition for the metalliding was found to be the current density, 50 to $150mA/\textrm{cm}^2$, the bath tem-perature, $57.5^{\circ}C$, and the amount of AlF3, 10wt.%. Addition of manganese fluoride (up to 5wt.%) as a co-de-posit element improved significantly the quality of the deposit layer.

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The Preparation of Alkenyl Fluorides form Organometallic Reagents

  • 이승한;Martin Riediker;Jeffrey Schwartz
    • Bulletin of the Korean Chemical Society
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    • 제19권7호
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    • pp.760-766
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    • 1998
  • Fluorination of alkenyllithium reagents can be accomplished in acceptable yield under conditions which give rise to low competitive alkene formation. These reactions are abetted by the use of the low temperature soluble, mild fluorinating agent N-fluoro-N-tert-butylbenzenesulfonamide; "simpler" fluorinating reagents such as F2, XeF2 or FClO3 failed to give acceptable amounts of the fluoroolefin with these alkenyllithiums.

플럭스 코어드 와이어의 불화물 종류에 따른 용접금속 산소량의 변화 (Effects of Fluorides in the Flux Cored Wire on the Oxygen Content of Weld Metal)

  • 차주현;방국수
    • 한국해양공학회지
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    • 제33권6호
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    • pp.615-619
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    • 2019
  • Various fluorides, i.e., CaF2, Na3AlF6, K2SiF6, MnF3, MgF2, were added to the flux cored wire, and their effects on the oxygen content of the weld metal were investigated. The investigation showed that the oxygen content of weld metal was not influenced by the type of metallic elements in the fluoride; rather, it was influenced by the stability of the arc during welding. While the wire containing MgF2 showed the most stable arc and the least amount of oxygen in the weld metal, the wire containing MnF3 showed the least stable arc and the greatest amount of oxygen. Since the deoxidation of the weld metal was not affected by the deoxidation elements, such as Ca and Mg, it was possible to predict the oxygen content of the weld metal by the equilibrium Si-Mn deoxidation thermodynamic model.

[18F]Aryl fluorides from hypervalent iodine compounds

  • Chun, Joong-Hyun;Son, Jeongmin;Park, Jun Young;Yun, Mijin
    • 대한방사성의약품학회지
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    • 제3권1호
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    • pp.3-14
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    • 2017
  • Nucleophilic aromatic fluorination has been one of the most explored methods in fluorin-18 based radiochemistry. Unlike electrophilic $[^{18}F]$fluorination methods, no-carrier-added nucleophilic radiofluorination with cyclotron-produced $[^{18}F]$fluoride ion offers better specific radioactivity which is essential aspect to obtain good quality images from positron emission tomography. Contrary to amenable aliphatic radiofluorination, the development of reliable aromatic $[^{18}F]$fluorination methods has been pursued by many research groups; however, no viable method has yet been established. Recently, hypervalent iodine compound draws increasing attention as versatile radiolabeling precursor for various $[^{18}F]$fluoroarenes, since it bears the capacity to introduce fluorine-18 either on electron-deficient or electron-rich aryl ring with enhanced regiospecificity. Other classes of hypervalent iodine congeners often utilized in radiochemistry are iodylarenes, iodonium ylides, and spirocyclic iodonium ylides. Recently developed spirocyclic iodonium ylides have already been avidly employed to provide various $[^{18}F]$aryl fluorides with high labeling efficiency. This metal-free protocol would afford efficient routes, replacing the traditional approaches to $[^{18}F]$fluoroarenes, from prosthetic labeling synthons to complex PET radiotracers.

불화물(弗化物)의 상아질도포효과(象牙質塗布效果)에 관(關)한 실험적(實驗的) 연구(硏究) (AN EXPERIMENTAL STUDY OF THE EFFECT OF FLUORIDES ON HUMAN DENTIN)

  • 전동문;민병순;최호영;박상진
    • Restorative Dentistry and Endodontics
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    • 제13권1호
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    • pp.23-38
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    • 1988
  • In order to investigate the material formed by application of fluoride on human dentin, exposed dentin of tooth cervix and sound dentin powder was treated by several fluoride solutions. The former was observed by scanning electron microscope and the latter was analysed by x-ray diffractometer and infrared spectrophotometer. The results obtained were as follows: 1. Application with NaF, $SnF_2$ and $Na_2PO_3F$ on exposed dentin of tooth cervix formed mineralized materials covered. 2. The amount of mineralized materials increased with time intervals of applying the fluorides. 3. The density of mineralized materials was highest in $Na_2PO_3F$ treatment group, and NaF treatment group was higher than $SnF_2$ treatment group. 4. $SnF_2$ remained in covering of mineralized materials. 5. Application with NaF and $Na_2PO_3F$ formed mineralized materials characterized apatitic crystals. 6. The crystallinity of mineralized materials was higher prominently in $Na_2PO_3F$ treatment group.

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Synthesis, Characterization and Catalytic Evaluation of Zinc Fluorides for Biodiesel Production

  • Indrayanah, Sus;Marsih, I Nyoman;Murwani, Irmina Kris
    • 대한화학회지
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    • 제62권1호
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    • pp.7-13
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    • 2018
  • The potential of zinc fluorides with different molar ratios of Zn/F was applied as a solid catalyst in the simultaneous reaction of transesterification and esterification of crude palm oil (CPO) for biodiesel production. These materials were prepared by the fluorolytic sol-gel technique with different fluorine contents. The resulting samples were investigated using elemental analysis, XRD, FT-IR, TG/DTG, $N_2$ physisorption measurements and SEM. The results exhibited that the presence of fluorine strongly affected the catalytic activity in the biodiesel production. The catalysts with smaller fluorine contents (${\leq}1$) showed the best performance in all of the observed samples, yields from 92.94 to 89.95, 87.38 and 85.21% with increasing fluorine contents, respectively. The yield toward the formation of biodiesel depended on the phase and particle sizes of catalysts, but it was not influenced by surface area, pore size, and volume of the samples. The recovered catalyst showed a gradual decrease in activity over three cycles of same reactions.

수산화아파타이트/알루미나 복합체의 기계적 특성에 미치는 불화물 첨가제의 영향 (Effect of Fluoride Additives on Mechanical Properties in Hydroxyapatite/Alumina Composites)

  • 김성환;방희곤;박상엽
    • 한국세라믹학회지
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    • 제43권1호
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    • pp.48-54
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    • 2006
  • Hydroxyapatite $(HAp,\;Ca_{10}(PO_4)_6(OH)_2)$/alumina composites were fabricated with the addition of fluorides, such as $MgF_2$ and $CaF_2$. In this study, the effect of fluorides on the inhibition of phase decomposition and the mechanical properties of HAp was investigated. Due to the higher solubility of F ion in HAp structure, $MgF_2$ additive was more effective compared to $CaF_2$ additive in the lowering decomposition temperature of HAp. Therefore, the dissociation tendency of HAp was fully inhibited below $1400^{\circ}C$. The mechanical properties of HAp composites with $MgF_2$ additive showed higher value (flexural strength: $\~170MPa$, Vickers hardness: $\~7\;GPa$, fracture toughness: $\~1.5\;MPam^{1/2}$) compared to $MgF_2-free$ composites. The linear thermal expansion coefficient of HAp composites with $MgF_2$ showed the value of $16.4\times10^{-6}/^{\circ}C\;at\;20\~400^{\circ}C $.

Reprocessing of fluorination ash surrogate in the CARBOFLUOREX process

  • Boyarintsev, Alexander V.;Stepanov, Sergei I.;Chekmarev, Alexander M.;Tsivadze, Aslan Yu.
    • Nuclear Engineering and Technology
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    • 제52권1호
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    • pp.109-114
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    • 2020
  • This work presents the results of laboratory scale tests of the CARBOFLUOREX (CARBOnate FLUORide EXtraction) process - a novel technology for the recovery of U and Pu from the solid fluorides residue (fluorination ash) of Fluoride Volatility Method (FVM) reprocessing of spent nuclear fuel (SNF). To study the oxidative leaching of U from the fluorination ash (FA) by Na2CO3 or Na2CO3-H2O2 solutions followed by solvent extraction by methyltrioctylammonium carbonate in toluene and purification of U from the fission products (FPs) impurities we used a surrogate of FA consisting of UF4 or UO2F2, and FPs fluorides with stable isotopes of Ce, Zr, Sr, Ba, Cs, Fe, Cr, Ni, La, Nd, Pr, Sm. Purification factors of U from impurities at the solvent extraction refining stage reached the values of 104-105, and up to 106 upon the completion of the processing cycle. Obtained results showed a high efficiency of the CARBOFLUOREX process for recovery and separating of U from FPs contained in FA, which allows completing of the FVM cycle with recovery of U and Pu from hardly processed FA.