• Title/Summary/Keyword: Nano size

Search Result 2,178, Processing Time 0.028 seconds

Effect of Crystallization Treatment on the Magnetic Properties of Amorphous Strips Based on Co-Fe-Ni-B-Si-Cr Containing Nitrogen

  • Cho H.J.;Kwon H.T.;Ryu H.H.;Sohn K.Y.;You B.S.;Park W.W.
    • Journal of Powder Materials
    • /
    • v.13 no.4 s.57
    • /
    • pp.285-289
    • /
    • 2006
  • Co-Fe-Ni-B-Si-Cr based amorphous strips containing nitrogen were manufactured via melt spinning, and then devitrified by crystallization treatment at the various annealing temperatures of $300^{\circ}C{\sim}540^{\circ}C$ for up to 30 minutes in an inert gas $(N_2)$ atmosphere. The microstructures were examined by using XRD and TEM and the magnetic properties were measured by using VSM and B-H meter. Among the alloys, the amorphous ribbons of $Co_{72.6}Fe_{9.8}Ni_{5.5}B_{2.4}Si_{7.1}Cr_{2.6}$ containing 121 ppm of nitrogen showed relatively high saturation magnetization. The alloy ribbons crystallized at $540^{\circ}C$ showed that the grain size of $Co_{72.6}Fe_{9.8}Ni_{5.5}B_{2.4}Si_{7.1}Cr_{2.6}$ alloy containing 121 ppm of nitrogen was about f nm, which exhibited paramagnetic behavior. The formation of nano-grain structure was attributed to the finely dispersed Fe4N particles and the solid-solutionized nitrogen atoms in the matrix. Accordingly, it can be concluded that the nano-grain structure of 5nm in size could reduce the core loss within the normally applied magnetic field of 300A/m at 10kHz.

The basic study for the proposal standard of Nano-Slag on an alternation material for Silica-fume (실리카퓸 대체 재료로서 나노슬래그의 규격제안을 위한 기초적 연구)

  • Heo, Jae-Won;Im, Nam-Gi
    • Proceedings of the Korean Institute of Building Construction Conference
    • /
    • 2008.11a
    • /
    • pp.67-71
    • /
    • 2008
  • Blast Furnace slag a pigiron waste that is produced more than 800 thousand tons per year, and micronized double quenching blast furnace slag improves flexibility of concrete, and even shows improvement effect of long-term intensity. However, the concrete that used micronized double quenching blast furnace slag is restricted in its use because of many problems to assure early intensity. Even micronized blast furnace slag can assure its early intensity of concrete when maximizing, and is considered that can be applied in high strength of blast furnace slag as an alternation material for Silica-fume that depends on overall import. Hereby this paper is revised activity index and fluidity of mortar that used Nano Slag that is produced by rotten Nano crush equipment to propose its size, and possible utility of Nano Slag that was produced by blast furnace slag made in Korea as an alternation material, with the conclusion as following. 1. To measure micronized Nano slag, it is judged that it should be in progress with BET method that is based on micronized Silica-fume for concrete. 2. As a result, the test based on KS L ISO 679 is shown to satisfy the basic additive size of KS F 2563 and of KS F 2567, and to determine new combination of stipulations. 3. The strength development of Nano Slag was shown excellent in the daily initial installment of 1, 3, 7 days against the basic additive. This is judged that contains CaO controlling initial strength against Silica-fume, and contributes to higher fineness than the basic blast furnace slag 1 type.

  • PDF

Synthesis of Nano Sized Cobalt Powder from Cobalt Sulfate Heptahydrate by Liquid Phase Reduction (액상환원공정을 이용한 황산코발트로부터의 코발트 나노분말 합성)

  • An, Se-Hwan;Kim, Se-Hoon;Lee, Jin-Ho;Hong, Hyun-Seon;Kim, Young-Do
    • Korean Journal of Materials Research
    • /
    • v.21 no.6
    • /
    • pp.327-333
    • /
    • 2011
  • Nanostructured cobalt materials have recently attracted considerable attention due to their potential applications in high-density data storage, magnetic separation and heterogeneous catalysts. The size as well as the morphology at the nano scale strongly influences the physical and chemical properties of cobalt nano materials. In this study, cobalt nano particles synthesized by a a polyol process, which is a liquid-phase reduction method, were investigated. Cobalt hydroxide ($Co(OH)_2$), as an intermediate reaction product, was synthesized by the reaction between cobalt sulphate heptahydrate ($CoSO_4{\cdot}7H_2O$) used as a precursor and sodium hydroxide (NaOH) dissolved in DI water. As-synthesized $Co(OH)_2$ was washed and filtered several times with DI water, because intermediate reaction products had not only $Co(OH)_2$ but also sodium sulphate ($Na_2SO_4$), as an impurity. Then the cobalt powder was synthesized by diethylene glycol (DEG), as a reduction agent, with various temperatures and times. Polyvinylpyrrolidone (PVP), as a capping agent, was also added to control agglomeration and dispersion of the cobalt nano particles. The optimized synthesis condition was achieved at $220^{\circ}C$ for 4 hours with 0.6 of the PVP/$Co(OH)_2$ molar ratio. Consequently, it was confirmed that the synthesized nano sized cobalt particles had a face centered cubic (fcc) structure and with a size range of 100-200 nm.

PLGA particles and half-shells prepared by double emulsion method: characterization and release profiles of ranitidine (이중 유제 방법으로 제조된 PLGA 미립자들과 반구체:특성과 라니티딘(ranitidine)의 방출 양상)

  • Nam, Dae-Sik;Kim, Seong-Cheol;Kang, Soo-Yong;Odonchimeg, Munkhjargal;Shim, Young-Key;Lee, Woo-Kyoung
    • Journal of Pharmaceutical Investigation
    • /
    • v.38 no.2
    • /
    • pp.99-104
    • /
    • 2008
  • PLGA micro/nano particles encapsulating ranitidine as a hydrophilic model drug were prepared by the double-emulsion solvent evaporation method. Surface morphology investigation by scanning electron microscope (SEM) showed that the emulsification by sonication could produce nanoparticles, whereas microparticles were prepared using high speed homogenizer. Moreover, while nanohalf-shell structure instead of spherical nanoparticle could be produced by adding poloxamer into oil phase (MC) with PLGA 504H, the addition of poloxamer didn't change particle shape in case of PLGA 502H. On the other hand, microparticle with poloxamer had more surface pores than those without poloxamer. The size and polydispersity (PDI) of particles were determined by particle size analyzer. Effective diameters of particles were in the range of $400{\sim}800\;nm$ and $1200{\sim}3300\;nm$ in case of nanoparticles and microparticles, respectively. Encapsulation efficiencies were in the range of $1.2{\sim}2.9%$. The addition of poloxamer produced the particles with higher encapsulation efficiency. In vitro release study in phosphate buffer (pH 7.4) at $37^{\circ}C$ showed common large initial burst release. However, the relative slower release profile could be observed in case of microparticles. Poloxamer addition increased the release rate, which was thought to be related to the increased surface area of particles.

N2 plasma treatment of pigments with minute particle sizes to improve their dispersion properties in deionized water

  • Zhang, Jingjing;Park, Yeong Min;Tan, Xing Yan;Bae, Mun Ki;Kim, Dong Jun;Jang, Tae Hwan;Kim, Min Su;Lee, Seung Whan;Kim, Tae Gyu
    • Journal of Ceramic Processing Research
    • /
    • v.20 no.6
    • /
    • pp.589-596
    • /
    • 2019
  • Pigments with minute particle sizes, such as carbon black (CB) and pigment red 48:2 (P.R.48:2), are the most important types of pigment and have been widely used in many industrial applications. However, minute particles have large surface areas, high oil absorption and low surface energy. They therefore tend to be repellent to the vehicle and lose stability, resulting in significant increases in viscosity or reaggregation in the vehicle. Therefore, finding the best way to improve the dispersion properties of minute particle size pigments presents a major technical challenge. In this study, minute particle types of CB and P.R.48:2 were treated with nitrogen gas plasma generated via radio frequency-plasma enhanced chemical vapor deposition (RF-PECVD) to increase the dispersion properties of minute particles in deionized (DI) water. The morphologies and particle sizes of untreated and plasma treated particles were evaluated using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The average distributions of particle size were measured using a laser particle sizer. Fourier transform infrared spectroscopy was carried out on the samples to identify changes in molecular interactions during plasma processing. The results of our analysis indicate that N2 plasma treatment is an effective method for improving the dispersibility of minute particles of pigment in DI water.

Condensation of Nano-Size Polymer Aggregates by Spin Drying

  • Ishikawa, Atsushi;Kawai, Akira
    • Journal of Adhesion and Interface
    • /
    • v.6 no.1
    • /
    • pp.7-10
    • /
    • 2005
  • Condensation control of nano-particles has become important in order to fabricate minute condensed structures. In this study, we focus our attention on condensation mechanism of polymer aggregates in a resist film. The polymer aggregate is structural component of a resist material which is used in lithography process. The condensation nature of polymer aggregates in the resist film surface is observed by using atomic force microscope (AFM). By using the AFM, the condensation of polymer aggregates can be observed clearly. The condensation of polymer aggregate strongly affects to precise fabrication of resist pattern below 100nm size. The interaction force among polymer aggregates can be analyzed based on Derjaguin approximation. We also discuss about condensation nature of polymer aggregates in the resist film surface with the help of micro sphere model.

  • PDF

Characteristics of TiO2 Particle Generation and Transport in Diffusion Flame Reactor (확산 화염 반응기에서의 TiO2 입자생성 및 전달현상)

  • Choi, Sang-Keun;Kim, Dong-Joo;Kim, Kyo-Seon
    • Journal of Industrial Technology
    • /
    • v.22 no.A
    • /
    • pp.255-260
    • /
    • 2002
  • We prepared the nano-sized $TiO_2$ particles by the diffusion flame reactor and investigated the effects of several process variables on the generation and transport properties of $TiO_2$ particle. As the length from the tip of diffusion flame reactor increases, the size of $TiO_2$ particle increases by the coagulation between particles. The structure of $TiO_2$ particles prepared is almost found to be anatase. It was found that the $TiO_2$ particle size depends more largely on the change of reactor temperature than on the change of inlet $TiCl_4$ concentration.

  • PDF

A Study on the Boundary Layer Thickness at a Liquid-Vapor Interface (기액계면의 경계층 두께에 관한 연구)

  • Choi, Soon-Ho;Song, Chi-Sung;Choi, Hyun-Kyu;Lee, Jung-Hye;Kim, Kyung-Kun
    • Proceedings of the KSME Conference
    • /
    • 2004.11a
    • /
    • pp.1086-1091
    • /
    • 2004
  • The boundary layer is a very important characteristic of a liquid-vapor interface since it governs the heat and mass transfer phenomena across an interface. However, the thickness of a boundary layer is generally micro- or nano-sized, which requires highly accurate measurement devices and, consequently, costs the related experiments very high and time-consuming. Due to these size dependent limitations, the experiments related with a nano-scaled size have suffered from the errors and the reliability of the obtained data. This study is performed to grasp the characteristics of a liquid-vapor interface, by using a molecular dynamics method. The simulation results were compared with other studies if possible. Although other studies reported that there existed a temperature discontinuity over an interface when the system was reduced to micro- or nano-sized, we confirmed that there was no such a temperature discontinuity.

  • PDF

Design of a High-Transmission C-Shaped Nano-Aperture in a Perfectly Electric Conductor Film (완전도체 박막에서 고 투과율 C형 나노 개구 설계)

  • Park Sin-Jeung;Hahn Jae-Won
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.23 no.6 s.183
    • /
    • pp.160-165
    • /
    • 2006
  • We have designed a high-transmission nano aperture in a perfect electric conductor film with the incident beam of 532 nm wavelength. The aperture basically has a C-shape and is known to produce a bright spot nearby the aperture in small size less than diffraction limit. The bright spot is strongly coupled with the local plasmon excited through the aperture hole. The characteristics of transmission and peak power of the aperture output were calculated using finite differential time domain (FDTD) technique, and the geometry of the aperture was determined to get a maximum transmission and peak power. To find the effect of the surface plasmon induced near by the aperture, we calculated the variations of the transmittance and the beam sizes by changing the size of the input beam irradiated on the aperture.

Collection Efficiency of Nano Particles by Electrostatic Precipitator using Dielectric Barrier Discharge (배리어 유전체 방전을 이용한 전기 집진부에서의 나노 입자 집진 효율)

  • Kang, Suk-Hoon;Ji, Jun-Ho;Byeon, Jeong-Hoon;Hwang, Jung-Ho
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.27 no.11
    • /
    • pp.1542-1547
    • /
    • 2003
  • Although dielectric barrier discharge (DBD) in air has been applied to a wider range of aftertreatment processes for HAPs (Hazardous Air Pollutants), due to its high electron density and energy, its potential use as precharging dust particles is not well known. In this work, we measured size distributions of bimodal aerosol particles and estimated collection efficiency of the particles by an electrostatic precipitator (ESP) using DBD as particle charger. To examine the particle collection with DBD charger, nano size particles of NaCl(20∼100nm) and DOS (50∼500nm) were generated by a tube furnace and an atomizer, respectively. For experimental conditions of 60㎐, 11㎸ and 60 lpm, the particle collection efficiency for the hybrid system was over 85%, based on the number of particles captured.