Preparation of Magnetic Expanded Graphite by Sol-Gel Method and its Electromagnetic Properties

2011 ◽  
Vol 295-297 ◽  
pp. 93-97 ◽  
Author(s):  
Qian Zhang ◽  
Jun Yan ◽  
Tian Peng Li ◽  
Jing Wang
Keyword(s):  
Composite Materials ◽  
Sol Gel ◽  
Magnetic Hysteresis ◽  
Expanded Graphite ◽  
Crystal Form ◽  
Electromagnetic Properties ◽  
Hysteresis Cycle ◽  
Magnetic Composite ◽  
Mean Size ◽  
The Mean

In order to transform the diamagnetism of expanded graphite (EG) to ferrimagnetism and improve its electromagnetic interferential capability, nano γ-Fe2O3/EG magnetic composite materials was prepared by sol-gel and low temperature self-combustion technique. The as prepared samples were characterized by SEM, XRD and Magnetic hysteresis cycle test. The results indicated that the composite materials had ferrimagnetism property after the embedding of γ-Fe2O3, but the average conductivity of the composites decreases gradually with the increase of γ-Fe2O3. Different mixing ratio of ferrite gel and graphite intercalation compounds produced ferric oxide with different crystal form and shape. When the content of ferrite sol was low, spherical γ-Fe2O3with the mean size of 31.69nm was formed, and spread unevenly on the surface and interformational micelles of EG. High content of ferrite sol (83wt%) produced more perfect crystal γ-Fe2O3of pentahedron shape with the mean size of 44.68nm, and a few of α-Fe2O3occurred which lead to the decline of the magnetic property of the composite materials.

scholarly journals Light Scattering of SiO Monodisperse Microspheres Prepared by the Sol-Gel Route

1988 ◽  
Vol 121 ◽  
Author(s):  
E. Ziemath ◽  
M. A. Aegerter ◽  
J. Moreira ◽  
M. Figueiredo ◽  
J. Zarzycki
Keyword(s):  
Light Scattering ◽  
Colloidal Silica ◽  
Hydrodynamic Radius ◽  
Sol Gel ◽  
Radius Of Gyration ◽  
Translational Diffusion Coefficient ◽  
Stöber Method ◽  
Mean Size ◽  
The Mean ◽  
The Stöber Method

ABSTRACTSiO microspheres have been prepared from TMOS/Methanol/water sols in basic condition (pH ≃ 12) by the Stöber method and studied by TEM static and dynamic light scattering techniques in order to determine the mean size Ṝ size distribution, hydrodynamic radius RH, radius of gyration RG and translational diffusion coefficient Dt; the ratio RH/RG was found less than 0.55 and the aggregates have a fractal geometry with df ∼ 2.3 ± 0.05. The results are compared to previous work on colloidal silica aggregates prepared by other techniques and discussed.

scholarly journals In vivo Evaluation of Marginal Microgaps of Sheep Incisors filled with Two Composite Materials

2009 ◽  
Vol 78 (4) ◽  
pp. 649-655
Author(s):  
Mária Figurová ◽  
Valent Ledecký ◽  
Svetoslav Štvrtina
Keyword(s):  
Composite Material ◽  
Composite Materials ◽  
Companion Animals ◽  
Type A ◽  
Permanent Teeth ◽  
Time Intervals ◽  
In Vivo Evaluation ◽  
Mean Size ◽  
The Mean

The aim of the study was to evaluate the marginal microgaps of two light-induced polymerization composite materials: Filtek P60 (3M ESPE) and Opticor New (Spofa Dental) in ovine teeth in vivo. The restorative materials were placed to type A-cavity to buccal surfaces of permanent teeth (Triadan system 301, 302, 303, 401, 402, 403). The variables of composite materials were evaluated in 3 groups of animals, 2 animals in each, at different time intervals (1, 6 and 9 months after beginning of the experiment). In various time intervals, 12 teeth per group were extracted under general injection anaesthesia, 6 teeth from each animal). Altogether 36 teeth were extracted throughout the experiment. During the experiment we observed neither cracks nor marginal discoloration in both Filtek P60 and Opticor New restorations. Retention of all restorations was 100%. Significant (P = 0.029 ANOVA) differences were observed in the dentin with Filtek P60 packable restorations which exhibited smaller marginal microgaps (OPTICOR NEW and dentin 11.09 mm, FILTEK P60 and dentin 5.64 μm). The mean size of microgaps between dentin and the packable composite material Filtek P60 was significantly lower (P = 0.029 ANOVA) in comparison with the microhybrid Opticor New composite restorations. These materials are suitable as permanent restoration of dental cervical caries in sheep and other herbivores, such as those kept in zoological gardens and companion animals.

Preparation of Ultrafine Polyethylene-Silica Composite Particle with Core-Shell Structure

2012 ◽  
Vol 557-559 ◽  
pp. 554-557 ◽  
Author(s):  
Lei Zu ◽  
Shun Yu Han ◽  
Kai Gu ◽  
Xiu Guo Cui
Keyword(s):  
Shell Structure ◽  
Composite Particle ◽  
Sol Gel ◽  
Core Shell ◽  
Silica Composite ◽  
Transmission Electron ◽  
Mean Size ◽  
The Mean ◽  
Core Shell Structure ◽  
Electronic Microscope

A novel ultrafine polyethylene/silica composite particle with core-shell structure was prepared by the sol-gel method in the presence of the melt polyethylene emulsion. A series of samples with different polyethylene content were prepared to investigate the unique characteristics of this original composite particle. The core-shell structure and composition of the composite particle was proved by the transmission electron microscopy observation and Fourier transform infrared spectra. The composite particles possess a spherical morphology and the mean size is about 160nm, presented by the scanning electronic microscope observation and nanoparticle tracking analysis, respectively.

scholarly journals Enhanced Permeability of Fe-Based Amorphous Powder Cores Realized through Selective Incorporation of Carbonyl Iron Powders at Inter-Particle Voids

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1220
Author(s):  
Hea-Ran Kim ◽  
Min-Sun Jang ◽  
Yeong-Gyun Nam ◽  
Yun-Seok Kim ◽  
Sang-Sun Yang ◽  
...  
Keyword(s):  
Carbonyl Iron ◽  
High Frequency ◽  
Eddy Currents ◽  
Sol Gel ◽  
Magnetic Domain ◽  
Amorphous Powder ◽  
Electromagnetic Properties ◽  
Magnetic Composite ◽  
Dc Bias ◽  
Power Inductors

In this study, we demonstrate a hybrid multimodal soft magnetic composite (SMC) comprising gas-atomized spherical amorphous powder (AP) and carbonyl-iron powder (CIP), and present its enhanced electromagnetic properties. CIP is selectively incorporated into voids between AP, and deforms during compression, effectively reducing the pores, resulting in high packing density of the core, where CIP magnetically bridges AP and helps magnetic domain rotation much efficiently. The hybrid SMC with the addition of 20 wt.% CIP showed constant effective permeability of 57 up to 1 MHz, a remarkable 63% increase compared with the AP core, while DC bias superimposing retention level of 61% was secured with the help of high magnetization of CIP. In addition, the effect of SiO2 surface insulation, prepared by the sol-gel process, on the high-frequency magnetic properties of hybrid SMCs, was also evaluated. It is thus revealed that the high-frequency dynamic loss of the hybrid core, originating from intra-particle eddy current loss and anomalous loss component, and inter-particle eddy currents are negligibly small. We believe that our approach using AP/CIP multimodal hybrid SMCs is an effective way of achieving high permeability as well as high DC bias characteristics at high frequencies. This process will be highly beneficial for the miniaturization of power inductors.

Effect of CeO2 Supports on CO Oxidation Activity of Pd-Cu Catalyst

2007 ◽  
Vol 336-338 ◽  
pp. 1992-1994
Author(s):  
Yu Jun Zhang ◽  
Jing Chao Zhang ◽  
Sha Li Tan ◽  
Xun Yan Tan
Keyword(s):  
Co Oxidation ◽  
Sol Gel ◽  
Complete Conversion ◽  
Oxidation Activity ◽  
Co Catalytic Oxidation ◽  
Cu Catalyst ◽  
Mean Size ◽  
Cu Catalysts ◽  
The Mean ◽  
Supported Pd

Nanometer CeO2 with the mean size of 15 nm is prepared by sol-gel method, and the CO catalytic oxidation activity of Pd-Cu catalysts with three kinds of CeO2 supports was studied. The results show that nanometer CeO2 supported Pd-Cu catalyst gives highest activity for CO oxidation. It can maintain CO complete conversion at about 40°C.

The Methods of Investigation of Complex Dielectric Permittivity of Layer Polymers Containing Conductive Inclusions

1990 ◽  
Vol 214 ◽  
Author(s):  
A.A. Kalachev ◽  
I.V. Kukolev ◽  
S.M. Matitsin ◽  
L.N. Novogrudskiy ◽  
K.N. Rozanov ◽  
...  
Keyword(s):  
Composite Materials ◽  
Dielectric Permittivity ◽  
Complex Dielectric Permittivity ◽  
High Dielectric Permittivity ◽  
Mean Size ◽  
The Mean ◽  
High Dielectric

ABSTRACTA set of methods for measure complex dielectric permittivity of layer materials at microwaves is suggested. These methods allow one to measure dielectric permittivity of composite materials in with the mean size of inhomogeneities is comparable with the wavelength and materials with high dielectric permittivity.

scholarly journals Preparation and electrochemical characterization of Pt nanoparticles dispersed on niobium oxide

2003 ◽  
Vol 28 (2) ◽  
pp. 69-76
Author(s):  
R. L. S. Mello ◽  
F. I. Mattos-Costa ◽  
H. de las M. Villullas ◽  
L. O. de S. Bulhões
Keyword(s):  
Niobium Oxide ◽  
Sol Gel ◽  
Pt Nanoparticles ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mean Size ◽  
The Mean ◽  
General Aspects ◽  
Titanium Substrates

Electrodes consisting of Pt nanoparticles dispersed on thin films of niobium oxide were prepared onto titanium substrates by a sol-gel method. The physical characterization of these electrodes was carried out by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray analysis. The mean size of the Pt particles was found to be 10.7 nm. The general aspects of the electrochemical behavior were studied by cyclic voltammetry in 1 mol L-1 HClO4 aqueous solution. The response of these electrodes in relation to the oxidation of formaldehyde and methanol in acidic media was also studied.

Sign in / Sign up

Export Citation Format

Share Document