• 제목/요약/키워드: Metallic particles

검색결과 231건 처리시간 0.023초

유체 내 전기선폭발법에 의한 은 나노입자 유체의 제조 및 특성 (Production and Properties of Ag Metallic Nanoparticle Fluid by Electrical Explosion of Wire in Liquid)

  • 박은주;;김지순;권영순;김진천;최혜선;정용훈
    • 한국분말재료학회지
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    • 제16권3호
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    • pp.217-222
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    • 2009
  • This paper presents a novel single-step method to prepare the Ag nanometallic particle dispersed fluid (nanofluid) by electrical explosion of wire in liquid, deionized water (DI water). X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM) and transmission electron microscope (TEM) were used to investigate the characteristics of the Ag nanofluids. Zeta potential was also used to measure the dispersion properties of the as-prepared Ag nanofluid. Pure Ag phase was detected in the nanofluids using water. FE-SEM analysis shows that the size of the particles formed in DI water was about 88 nm and Zeta potential value was about -43.68 without any physical and chemical treatments. Thermal conductivity of the as-prepared Ag particle dispersed nanofluid shows much higher value than that of pure DI water.

Nanoparticle Induced Oxidative Stress in Cancer Cells: Adding New Pieces to an Incomplete Jigsaw Puzzle

  • Nogueira, Daniele Rubert;Rolim, Clarice M. Bueno;Farooqi, Ammad Ahmad
    • Asian Pacific Journal of Cancer Prevention
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    • 제15권12호
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    • pp.4739-4743
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    • 2014
  • Nanotechnology is an emerging field with many promising applications in drug delivery systems. Because of outstanding developments in this field, rapidly increasing research is directed to the development of nanocarriers that may enhance the availability of drugs to the target sites. Substantial fraction of information has been added into the existing scientific literature focusing on the fact that nanoparticles usually generate reactive oxygen species to a greater extent than micro-sized particles. It is worth mentioning that oxidative stress regulates an array of cell signaling cascades that resulted in cancer cell damage. Accumulating experimental evidence over the years has shown that wide-ranging biological mechanisms are triggered by these NPs in cultured cells due to the unique properties of engineered nanoparticles. In this review, we have attempted to provide an overview of the signaling cascades that are activated by oxidative stress in cancer cells in response to different kinds of nanomaterials, including quantum dots, metallic and polymeric nanoparticles.

TiAl 합금의 주형계면반응 및 유동성 평가 (Evaluation of Metal-mold Reactions and Fluidity of TiAl Alloys)

  • 이상화;성시영;최봉재;김명균;김영직
    • 한국주조공학회지
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    • 제26권2호
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    • pp.98-103
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    • 2006
  • Metal-mold reactions between investment mold and TiAl alloys were investigated for the economic net-shape forming of TiAl alloys. The effect of mold preheating temperatures on the metal-mold reaction were investigated using a vacuum induction-melting furnace. In the case of TiAl alloys, there were no ${\alpha}$-case formation reactions. There were neither interstitial nor substitutional ${\alpha}$-case formations as TiAl alloys have both negligible solubility of oxygen and low activity in molten states. The fluidity of TiAl alloys increases with mold preheating temperature since they have a peritectic reaction that appears in the form of envelope, surrounding each particles of the primary constituent. The results of the investment casting of TiAl alloys confirm that the casting route in our study can be an effective approach for the economic net-shape forming of TiAl alloys.

Ion Beam을 이용한 사파이어($Al_2O_3$) 표면개질 및 금(Au) 박막증착: 접합성 향상 및 접학기구에 대한 연구 (Ion beam induced surface modifications of sapphire and gold film deposition: studies on the adhesion enhancement and mechanisms)

  • 박재원;이광원;이재형;최병호
    • 한국진공학회지
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    • 제8권4B호
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    • pp.514-518
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    • 1999
  • Gold (Au) is not supposed to react with sapphire(single crystalline ) under thermodynamic equillibrium, therefore, a strong adhesion between these two dissimilar materials is not expected. However, pull test showed that the gold film sputter-deposited onto annealed and pre-sputtered sapphire exhibited very strong adhesion even without post-deposition annealing. Strongly and weakly adhered samples as a result of the pull testing were selected to investigate the adhesion mechanisms with Auger electron spectroscopy. The Au/ interfaces were analyzed using a new technique that probes the interface on the film using Auger electron escape depth. It revealed that one or two monolayers of Au-Al-O compound formed at the Au/Sapphire interface when AES in the UHV chamber. It showed that metallic aluminum was detected on the surface of sapphire substrates after irradiating for 3 min. with 7keV Ar+ -ions. These results agree with TRIM calculations that yield preferential ion-beam etching. It is concluded that the formation of Au-Al-O compound, which is responsible for the strong metal-ceramic bonding, is due to ion-induced cleaning and reduction of the sapphire surface, and the kinetic energy of depositing gold atoms, molecules, and micro-particles as a driving force for the inter-facial reaction.

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CO$_2$ 분해 반응에서 금속 산화물이 첨가된 $Fe_2O_4$의 영향 (Effects of Magnetite added with Metallic Oxide on the Decomposition Reaction of Carbon Dioxide)

  • Kim, Seung-Ho;Park, Young-Goo
    • 한국환경보건학회지
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    • 제24권1호
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    • pp.32-37
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    • 1998
  • The Carbon Dioxide is the gas, which causes green house effects, unusual changes in the weather, destruction of the life. Almost every nation in the world is trying to search the countermeasure to this poisonous gas. I synthesized $Fe_3O_4$ and NaOH, in order to decompose the Carbon Dioxide. Among the particles synthesizing $Fe_3O_4$, I chose the equivalent ratio 1.00 which can decompose the Carbon Dioxide best, and fixed that equivalent ratio and added the 0.005-3.00 mole percentage of NiCl$_2$ and synthesized $Fe_3O_4$. I studied the decomposition of the Carbon Dioxide and methanized reaction, by measuring its crystal structure, thermochemistrical character and specific surface area. In decomposing the Carbon Dioxide, I used oxygen-deficit Magnetite which I produced by injecting the hydrogen gas into the synthesized sample. I observed the methanization reaction by raising the temperature of sample up to 650$\circ$C and having it reacted with the hydrogen gas. The decomposition of the Carbon Dioxide was added 0.005, 0.03, 0.05 mole percentage of NiCl$_2$ was more effective than pure $Fe_3O_4$. All sample in which the decomposition of the Carbon Dioxide took place produced the methane gas.

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$CF_4$ 플라즈마에서 반응성 이온식각한 알루미늄 박막의 표면분석 (Surface analysis of reactively ion-etched aluminum films in $CF_4$ plasma)

  • 김동원;이원종
    • 한국결정성장학회지
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    • 제5권4호
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    • pp.351-357
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    • 1995
  • $CF_4$ 플라즈마 분위기에서 반응성 이온식각된 알루미늄의 표면을 XPS 분석하였다. 알루미늄의 표면에$AlF_3$가 형성되었으며 표면에서의 깊이가 깊어질수록 Al - F 결합에 의한 $Al_{2p}$ peak 강도가 감소하고 금속 알루미늄 결합에 의한 $Al_{2p}$ peak 강도가 증가하였다. 입자의 충돌에 의해서 표면원자들이 mixing 됨으로써 알루미늄의 표면에 50~100 $\AA$ 정도의 두께를 가진 $AlF_x$ 층이 형성되는 것으로 분석되었다. 같은 조건에서 반응성 이온식각된 알루미늄 산화막의 경우에는 mixing 효과가 알루미늄보다 작으므로 상대적으로 얕은 범위(10~20 $\AA$)에서 F가 O를 치환하여 $AlF_x$층이 형성되었다.

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Removal Efficiency of the Pollutants from Piggery Wastes with Activated Carbon Treated with Metal and Their Pilot Scale Design

  • Oh, Won-Chun;Park, Chong-Sung;Bae, Jang-Soon;Ko, Young-Shin
    • Carbon letters
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    • 제7권3호
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    • pp.180-187
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    • 2006
  • The treatment of piggery wastes was carried out at pilot scale using a multilayered metal-activated carbon system followed by carbon bed filtration. The physicochemical properties were obtained from treated samples with aqueous solutions containing metallic ions such as $Ag^+$, $Cu^{2+}$, $Na^+$, $K^+$ and $Mn^{2+}$, which main obsevations are subjected to inspect surface properties, color removal properties by Uv/Vis and EDX. Multilayered metal-activated carbons were contacted with waste water to investigation of the simultaneous catalytic effect for the COD, BOD, T-N and T-P removal. The removal results for the piggery waste using multilayered metal-activated carbon bed was achieved the satisfactory removal performance under permitted values of Ministry of Environment of Korea. The high efficiency of the multilayered metal-activated carbon bed was determined by the performance of this material for trapping, catalytic effect and adsorption of organic solid particles.

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Electrodes for contact electric welding of aluminium alloys

  • Bondar, M.P.;Moon, J.G.
    • 대한용접접합학회:학술대회논문집
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    • 대한용접접합학회 1997년도 특별강연 및 추계학술발표 개요집
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    • pp.184-193
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    • 1997
  • Aluminium and aluminium alloys have the high electrical and heat conductivity. It gives rise to difficulties for a choice of electrodes material for their contact electric welding. This paper describes the investigations performed to solve the above problem. The purpose of this investigation was to obtain dispersion-hardening alloys by the internal oxidation method, to optimize their contents and treatment modes, to produce electrodes of these alloys and to test them. The strengthing effect of alloys with oxide particles depends on their size stability at high temperatures. Despite of the fact, that oxides are the most stable of all the non-metallic phases their coagulation takes place. Based on the early results, we chose two types of alloys, first No. 1 Cu - 0,4%Al and second No. 2 Cu - 0,2%Be for production of electrodes. These alloys had not additional alloying elements. These alloys were prepared as 1 mm plates and flake-formed 200 m thick, and also No. 1 as a powder of size 100 mkm (received from Korea). The large samples for electrodes were produced by three methods : explosive welding method, dynamic one including the explosion compression of electrode blank and the quasi-dynamic method including the high-speed compression of dense briquest and the further hot extrusion of a rod.

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초고압 XLPE 케이블용 조립형 직선 접속함을 모의한 계면질서의 부분방전 패턴 연구 (A Study of Partial Discharge Patterns On the Simulated Interface of Prefabricated Joint for Ultra Power Cable)

  • 백주흠;김정년;신두성;이창영;김충식;김동욱;박완기
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1999년도 추계학술대회 논문집 학회본부 C
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    • pp.1102-1104
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    • 1999
  • It is very essential to find out defects and remove them in the insulation at the early stage because the defects in the insulation induce PD which deteriorates the material, resulting in the breakdown. In the real application of high voltage, the interface of the different insulation is the weakest place for both electrical and mechanical aspects. In this paper, characteristics of PD caused by the artificial defects, such as metallic particles, voids and moist fibers, at the interfaces of the cable joint (PJB) were investigated using the specially designed electrode system.

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새로운 게터소재로서의 금속 나노 분말 (Metal Nano Powders as a New Getter Material)

  • 김원백;박제신;서창열;장한권;이재천;박미영
    • 한국분말재료학회지
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    • 제14권1호
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    • pp.56-62
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    • 2007
  • Getter property of nano-sized metallic powders was evaluated as a possible candidate for the future getter material. For the purpose, Ti powders of about 50 nm were prepared by electrical wire explosion. Commercial Ti powders of about 22 micrometer were tested as well for comparison. The room-temperature hydrogen-sorption speed of nano-sized Ti powders was $1.34\;L/sec{\cdot}cm^{2}$ which was more than 4 times higher than that of micron-sized ones. The value is comparable to or even higher than those of commercial products. Its sorption speed increases with activation temperature up to $500^{\circ}C$ above which it deteriorates due to low-temperature sintering effect of nano-sized particles.