scholarly journals Influences of Dispersions’ Shapes and Processing in Magnetic Field on Thermal Conductibility of PDMS–Fe3O4 Composites

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3696
Author(s):  
V. Stancu ◽  
A. Galatanu ◽  
M. Enculescu ◽  
M. Onea ◽  
B. Popescu ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Thermal Conductivity ◽  
Magnetic Particles ◽  
Polymerization Process ◽  
Molding Process ◽  
Dispersed Particles ◽  
Magnetite Fe3o4 ◽  
Magnetic Dispersions ◽  
Oriented Samples ◽  
Compositional Properties

Composites of magnetite (Fe3O4) nanoparticles dispersed in a polydimethylsiloxane (PDMS) matrix were prepared by a molding process. Two types of samples were obtained by free polymerization with randomly dispersed particles and by polymerization in an applied magnetic field. The magnetite nanoparticles were obtained from magnetic micrograins of acicular goethite (α-FeOOH) and spherical hematite (α-Fe2O3), as demonstrated by XRD measurements. The evaluation of morphological and compositional properties of the PDMS:Fe3O4 composites, performed by SEM and EDX, showed that the magnetic particles were uniformly distributed in the polymer matrix. Addition of magnetic dispersions promotes an increase of thermal conductivity compared with pristine PDMS, while further orienting the powders in a magnetic field during the polymerization process induces a decrease of the thermal conductivity compared with the un-oriented samples. The shape of the magnetic dispersions is an important factor, acicular dispersions providing a higher value for thermal conductivity compared with classic commercial powders with almost spherical shapes.

Thermal Property Enhancement of Liquid Metal Used As Thermal Interface Material by Mixing Magnetic Particles

2019 ◽  
Author(s):  
Xianfeng Ma ◽  
Gen Li ◽  
Xuelin Zheng ◽  
Xiaozhong Wang ◽  
Zhongcheng Wang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Thermal Conductivity ◽  
Liquid Metal ◽  
Magnetic Particles ◽  
Nickel Particle ◽  
Field Application ◽  
Thermal Interface Material ◽  
Thermal Interface ◽  
Micro Particles ◽  
Steady State Method

Abstract The usage of low melting temperature alloys (LMAs) as thermal interface materials (TIMs) has attracted more and more attention for their high thermal conductivity. However, the wettability between liquid metal and ordinary metal surface was poor, which results in high thermal interface resistance. The thermal and physical properties of LMAs can be modified by adding nano or micro particles. In this study, the room temperature liquid metal (gallium, indium and tin eutectic) was used as TIM and its properties were modified by mixing magnetic nickel particles. Further, the effects of magnetic field application on the thermal performance of modified LMAs were evaluated by steady state method with specially designed sample holder. Results showed that the thermal conductivity of liquid metal mixed with nickel particle increased from 27.33 W/(m · K) to 33.33 W/(m · K) with the application of magnetic field.

Analysis of magneto rheological elastomers for energy harvesting systems

2020 ◽  
Vol 64 (1-4) ◽  
pp. 439-446
Author(s):  
Gildas Diguet ◽  
Gael Sebald ◽  
Masami Nakano ◽  
Mickaël Lallart ◽  
Jean-Yves Cavaillé
Keyword(s):  
Magnetic Field ◽  
Energy Harvesting ◽  
Shear Strain ◽  
Magnetic Induction ◽  
Magnetic Particles ◽  
Homogeneous Magnetic Field ◽  
Electrical Signal ◽  
Harvesting Systems ◽  
Dc Bias ◽  
Magneto Rheological

Magneto Rheological Elastomers (MREs) are composite materials based on an elastomer filled by magnetic particles. Anisotropic MRE can be easily manufactured by curing the material under homogeneous magnetic field which creates column of particles. The magnetic and elastic properties are actually coupled making these MREs suitable for energy conversion. From these remarkable properties, an energy harvesting device is considered through the application of a DC bias magnetic induction on two MREs as a metal piece is applying an AC shear strain on them. Such strain therefore changes the permeabilities of the elastomers, hence generating an AC magnetic induction which can be converted into AC electrical signal with the help of a coil. The device is simulated with a Finite Element Method software to examine the effect of the MRE parameters, the DC bias magnetic induction and applied shear strain (amplitude and frequency) on the resulting electrical signal.

scholarly journals Preparation and Thermal Conductivity of Epoxy Resin/Graphene-Fe3O4 Composites

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2013
Author(s):  
Zhong Wu ◽  
Jingyun Chen ◽  
Qifeng Li ◽  
Da-Hai Xia ◽  
Yida Deng ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Thermal Conductivity ◽  
Thermal Stability ◽  
Epoxy Resin ◽  
Thermomechanical Properties ◽  
Packaging Materials ◽  
Mass Ratio ◽  
Degree Of Orientation ◽  
Ep Matrix ◽  
Electrical Insulation Properties

By modifying the bonding of graphene (GR) and Fe3O4, a stable structure of GR-Fe3O4, namely magnetic GR, was obtained. Under the induction of a magnetic field, it can be orientated in an epoxy resin (EP) matrix, thus preparing EP/GR-Fe3O4 composites. The effects of the content of GR and the degree of orientation on the thermal conductivity of the composites were investigated, and the most suitable Fe3O4 load on GR was obtained. When the mass ratio of GR and Fe3O4 was 2:1, the thermal conductivity could be increased by 54.8% compared with that of pure EP. Meanwhile, EP/GR-Fe3O4 composites had a better thermal stability, dynamic thermomechanical properties, and excellent electrical insulation properties, which can meet the requirements of electronic packaging materials.

scholarly journals Optical Imaging of Magnetic Particle Cluster Oscillation and Rotation in Glycerol

2021 ◽  
Vol 7 (5) ◽  
pp. 82
Author(s):  
River Gassen ◽  
Dennis Thompkins ◽  
Austin Routt ◽  
Philippe Jones ◽  
Meghan Smith ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Particles ◽  
Magnetic Particle ◽  
Barium Hexaferrite ◽  
Optical Microscope ◽  
Simplified Model ◽  
Particle Cluster ◽  
Average Deviation ◽  
Cross Sectional

Magnetic particles have been evaluated for their biomedical applications as a drug delivery system to treat asthma and other lung diseases. In this study, ferromagnetic barium hexaferrite (BaFe12O19) and iron oxide (Fe3O4) particles were suspended in water or glycerol, as glycerol can be 1000 times more viscous than water. The particle concentration was 2.50 mg/mL for BaFe12O19 particle clusters and 1.00 mg/mL for Fe3O4 particle clusters. The magnetic particle cluster cross-sectional area ranged from 15 to 1000 μμm2, and the particle cluster diameter ranged from 5 to 45 μμm. The magnetic particle clusters were exposed to oscillating or rotating magnetic fields and imaged with an optical microscope. The oscillation frequency of the applied magnetic fields, which was created by homemade wire spools inserted into an optical microscope, ranged from 10 to 180 Hz. The magnetic field magnitudes varied from 0.25 to 9 mT. The minimum magnetic field required for particle cluster rotation or oscillation in glycerol was experimentally measured at different frequencies. The results are in qualitative agreement with a simplified model for single-domain magnetic particles, with an average deviation from the model of 1.7 ± 1.3. The observed difference may be accounted for by the fact that our simplified model does not include effects on particle cluster motion caused by randomly oriented domains in multi-domain magnetic particle clusters, irregular particle cluster size, or magnetic anisotropy, among other effects.

scholarly journals Carbon-coated Fe3O4 core–shell super-paramagnetic nanoparticle-based ferrofluid for heat transfer applications

2021 ◽  
Author(s):  
Mohd Imran ◽  
Nasser Zouli ◽  
Tansir Ahamad ◽  
Saad M. Alshehri ◽  
Mohammed Rehaan Chandan ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Thermal Conductivity ◽  
External Magnetic Field ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Carbon Coated ◽  
Core Shell Nanoparticles ◽  
Fe3o4 Core

Ferrofluids prepared by dispersing superparamagnetic Fe3O4@C core–shell nanoparticles in water exhibited exceptional enhancement in thermal conductivity without an external magnetic field.

scholarly journals Thermal conductivity in 3D NJL model under external magnetic field

2003 ◽  
Vol 33 (4) ◽  
pp. 397-411 ◽  
Author(s):  
E. J. Ferrer ◽  
V. P. Gusynin ◽  
V. de la Incera
Keyword(s):  
Magnetic Field ◽  
Thermal Conductivity ◽  
External Magnetic Field ◽  
Njl Model
Sign in / Sign up

Export Citation Format

Share Document