Magnetic Properties of Ferrogels

2010 ◽  
Author(s):  
Kelsey Cooper ◽  
LeAnn Faidley ◽  
Sarah Timmons ◽  
Yi Han ◽  
Wei Hong
Keyword(s):  
Magnetic Field ◽  
Magnetic Properties ◽  
Carbonyl Iron ◽  
External Factors ◽  
Poly Vinyl Alcohol ◽  
Pickup Coil ◽  
Active Behavior ◽  
Wide Range ◽  
Excitation Frequencies ◽  
Iron Concentrations

This paper presents the magnetic properties of ferrogels subject to cyclic magnetic fields. Ferrogels are compliant materials composed of a nonmagnetic, flexible matrix with a micro- or nano-sized magnetic powder filler. In this paper a poly-vinyl-alcohol matrix is chemically cross-linked with sodium tetraborate and micro-sized particles of carbonyl iron are dispersed randomly in the sample. Ferrogels exhibit active behavior characterized by a deformation, a stiffness increase, and a change of other properties when subjected to a magnetic field making them promising future actuator materials. Furthermore, since the composition of ferrogels can be easily varied the active properties of these materials can be designed over a wide range of possibilities. In order for this to be possible however, a thorough understanding of the active behavior of these materials and its dependence on external factors is necessary. This paper focuses on the magnetic properties of PVA/carbonyl iron ferrogels and how they are dependent on internal and external factors. Magnetization of the ferrogel sample will be measured under a uniform, sinusoidal magnetic field for constrained and unconstrained samples with various iron concentrations and under a range of excitation frequencies. Uniform excitation fields of up to 500 G are created by passing current through a coil that is substantially larger than the sample size. Excitation frequencies of 0.1 Hz to 20 Hz and iron concentrations of 12 wt%, 20 wt% and 27 wt% are investigated. The magnetization is determined by measuring the voltage induced in a pickup coil that surrounds the ferrogel sample. The objective of these tests is to investigate the magnetic properties of a poly-vinylalcohol/carbonyl iron ferrogel to help in the future design of ferrogels for specific applications.

Magnetic Properties of Frozen Magneto-Active Elastomers

2009 ◽  
Vol 152-153 ◽  
pp. 190-193 ◽  
Author(s):  
G.V. Stepanov ◽  
Dmitry Yu. Borin ◽  
Stefan Odenbach ◽  
A.I. Gorbunov
Keyword(s):  
Magnetic Field ◽  
Magnetic Properties ◽  
External Magnetic Field ◽  
Carbonyl Iron ◽  
Magnetic Fluids ◽  
Zero Field ◽  
Iron Particles ◽  
Temperature Dependent ◽  
Magnetization Measurements ◽  
Temperature Dependent Magnetization

In the present paper we report temperature dependent magnetization measurements done on a magneto-active elastomers (MAEs) consisting of a siloxane rubber filled with carbonyl iron particles. The experiments performed in this study are similar to the conventional Zero-Field-Cooled and Field-Cooled magnetic tests. To the best of our knowledge, this approach, successfully used for studies on magnetic fluids, has never ever been applied to MAE. This test allowed us to reveal the effect of change of MAE structure under the action of an external magnetic field.

Sensor Behavior of Magneto-Rheological Elastomers

2010 ◽  
Author(s):  
LeAnn Faidley ◽  
Christina Tringides ◽  
Wei Hong
Keyword(s):  
Magnetic Field ◽  
Magnetic Properties ◽  
Strain Rate ◽  
Large Strain ◽  
Pickup Coil ◽  
Constant Bias ◽  
Inverse Effect ◽  
Length Width ◽  
Theoretical Mechanism ◽  
Magneto Rheological

Magneto-Rheological Elastomers (MREs) are composite materials of an elastomer matrix with a magnetic, micron-sized, powder filler. These materials have gained notoriety because they change stiffness substantially when exposed to a magnetic field giving them the capability of acting as a variable spring for numerous applications. Magnetic field induced strain has also been measured in these materials making them feasible as future actuator materials. However, the inverse effect involving a mechanically induced change in the magnetic properties of these materials has yet to be studied in great detail. This paper presents the results of an experimental study of this sensor behavior. Sheets of 5 mm thick MRE are synthesized from silicone rubber (RTV6186) and carbonyl iron power with a diameter of 9 micrometers. The application of a magnetic field during the silicone curing process allows for the creation of samples with particles aligned along the length, width, and thickness of the sample as well as unaligned samples. These samples are then strained up to 100% of their test length while exposed to various constant bias fields. The change in the internal magnetic properties of the sample as it is strained induces a voltage in a pickup coil that surrounds the sample. This voltage is found to closely track the applied strain-rate making these materials promising for large strain, non-contact strain-rate sensors. In this paper this effect is described in detail experimentally and a theoretical mechanism is proposed to describe this sensing ability. The experimental results for testing MRE samples of 4 alignments in 3 bias fields and at 3 frequencies are presented for cyclic input and the sensitivity, linearity, and repeatability are discussed. Additionally, the results of tests with random inputs are also shown.

scholarly journals Possibile Applications of Magnetic Microwires in Aviation

2014 ◽  
Vol 2013 (5) ◽  
pp. 12-17
Author(s):  
Katarína Draganová ◽  
Josef Blažek ◽  
Dušan Praslička ◽  
František Kmec
Keyword(s):  
Magnetic Field ◽  
Magnetic Properties ◽  
Tensile Stress ◽  
Temperature Sensors ◽  
Sensing Element ◽  
Magnetic Field Sensors ◽  
Magnetic Microwires ◽  
Stress Sensors ◽  
Wide Range ◽  
Potential Applications

Abstract Magnetic microwires have been rediscovered due to a number of the unusual magnetic properties and their potential applications. The paper concerns glass-coated magnetic microwires composed of a ferromagnetic metallic core with a diameter of 0.6 - 30 jj.m and of a glass coat with a thickness of 2 - 20 jj.m. The fabrication process and magnetic properties of these microwires are described. Due to their unique properties microwires can be used as a sensing element of sensors. Microwire-based sensors can be used in a wide range of aviation applications as magnetic field sensors, tensile stress sensors or temperature sensors. The main advantages of microwire-based sensors are associated with their small dimensions and weight, which play a very important role in aviation.

Monte Carlo calculation of the energy parameters and spatial distribution of the cathodic arc ions while passing through the macro-particles filters

2018 ◽  
Vol 1 (1) ◽  
pp. 30-34 ◽  
Author(s):  
Alexey Chernogor ◽  
Igor Blinkov ◽  
Alexey Volkhonskiy
Keyword(s):  
Magnetic Field ◽  
Mass Transfer ◽  
Monte Carlo ◽  
Monte Carlo Calculation ◽  
Inhomogeneous Magnetic Field ◽  
Flow Energy ◽  
Wide Range ◽  
Field Concentrator ◽  
Cathodic Arc ◽  
The Magnetic Field

The flow, energy distribution and concentrations profiles of Ti ions in cathodic arc are studied by test particle Monte Carlo simulations with considering the mass transfer through the macro-particles filters with inhomogeneous magnetic field. The loss of ions due to their deposition on filter walls was calculated as a function of electric current and number of turns in the coil. The magnetic field concentrator that arises in the bending region of the filters leads to increase the loss of the ions component of cathodic arc. The ions loss up to 80 % of their energy resulted by the paired elastic collisions which correspond to the experimental results. The ion fluxes arriving at the surface of the substrates during planetary rotating of them opposite the evaporators mounted to each other at an angle of 120° characterized by the wide range of mutual overlapping.

Investigation of the Structure and Magnetic Properties of Bulk Amorphous FeCoYB Alloy

2017 ◽  
Vol 68 (9) ◽  
pp. 2162-2165 ◽  
Author(s):  
Katarzyna Bloch ◽  
Mihail Aurel Titu ◽  
Andrei Victor Sandu
Keyword(s):  
Magnetic Field ◽  
Magnetic Properties ◽  
Hyperfine Field ◽  
Irreversible Processes ◽  
Magnetization Process ◽  
Casting Method ◽  
The Core ◽  
Injection Casting ◽  
Core Losses ◽  
Microstructural Studies

The paper presents the results of structural and microstructural studies for the bulk Fe65Co10Y5B20 and Fe63Co10Y7B20 alloys. All the rods obtained by the injection casting method were fully amorphous. It was found on the basis of analysis of distribution of hyperfine field induction that the samples of Fe65Co10Y5B20 alloy are characterised with greater atomic packing density. Addition of Y to the bulk amorphous Fe65Co10Y5B20 alloy leads to the decrease of the average induction of hyperfine field value. In a strong magnetic field (i.e. greater than 0.4HC), during the magnetization process of the alloys, where irreversible processes take place, the core losses associated with magnetization and de-magnetization were investigated.

scholarly journals The Location of Magnetic Reconnection at Earth’s Magnetopause

2021 ◽  
Vol 217 (3) ◽  
Author(s):  
K. J. Trattner ◽  
S. M. Petrinec ◽  
S. A. Fuselier
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Magnetic Reconnection ◽  
Ion Beams ◽  
Review Article ◽  
Observational Evidence ◽  
Magnetic Shear ◽  
General Direction ◽  
Shear Model ◽  
Wide Range

AbstractOne of the major questions about magnetic reconnection is how specific solar wind and interplanetary magnetic field conditions influence where reconnection occurs at the Earth’s magnetopause. There are two reconnection scenarios discussed in the literature: a) anti-parallel reconnection and b) component reconnection. Early spacecraft observations were limited to the detection of accelerated ion beams in the magnetopause boundary layer to determine the general direction of the reconnection X-line location with respect to the spacecraft. An improved view of the reconnection location at the magnetopause evolved from ionospheric emissions observed by polar-orbiting imagers. These observations and the observations of accelerated ion beams revealed that both scenarios occur at the magnetopause. Improved methodology using the time-of-flight effect of precipitating ions in the cusp regions and the cutoff velocity of the precipitating and mirroring ion populations was used to pinpoint magnetopause reconnection locations for a wide range of solar wind conditions. The results from these methodologies have been used to construct an empirical reconnection X-line model known as the Maximum Magnetic Shear model. Since this model’s inception, several tests have confirmed its validity and have resulted in modifications to the model for certain solar wind conditions. This review article summarizes the observational evidence for the location of magnetic reconnection at the Earth’s magnetopause, emphasizing the properties and efficacy of the Maximum Magnetic Shear Model.

scholarly journals Sensitivity of PS/CoPd Janus particles to an external magnetic field

RSC Advances ◽  
2021 ◽  
Vol 11 (28) ◽  
pp. 17051-17057
Author(s):  
Anna Eichler-Volf ◽  
Yara Alsaadawi ◽  
Fernando Vazquez Luna ◽  
Qaiser Ali Khan ◽  
Simon Stierle ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Properties ◽  
External Magnetic Field ◽  
Magnetic Fields ◽  
Janus Particles ◽  
Weak Magnetic Fields

PS/CoPd Janus particles respond very sensitively to application of low external magnetic fields. Owing to the magnetic properties, the PS/CoPd particles may be used, for example, to sense the presence of weak magnetic fields as micro-magnetometers.

Influence of a Magnetic Field on the Growth and Magnetic Properties of Zn0.15Fe2.85O4 Nanoparticle Chains

2021 ◽  
Vol 125 (3) ◽  
pp. 2045-2054
Author(s):  
Xiaochao Zhou ◽  
Zhaoxia Kou ◽  
Wen Zhang ◽  
Meijuan Wang ◽  
Jun Du ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Properties ◽  
Nanoparticle Chains

scholarly journals No-z Model for Magnetic Fields of Different Astrophysical Objects and Stability of the Solutions

Data ◽  
2021 ◽  
Vol 6 (1) ◽  
pp. 4
Author(s):  
Evgeny Mikhailov ◽  
Daniela Boneva ◽  
Maria Pashentseva
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Large Scale ◽  
Point Of View ◽  
Accretion Discs ◽  
Wide Range ◽  
Astrophysical Objects ◽  
Alpha Effect ◽  
The Stability ◽  
The Magnetic Field

A wide range of astrophysical objects, such as the Sun, galaxies, stars, planets, accretion discs etc., have large-scale magnetic fields. Their generation is often based on the dynamo mechanism, which is connected with joint action of the alpha-effect and differential rotation. They compete with the turbulent diffusion. If the dynamo is intensive enough, the magnetic field grows, else it decays. The magnetic field evolution is described by Steenbeck—Krause—Raedler equations, which are quite difficult to be solved. So, for different objects, specific two-dimensional models are used. As for thin discs (this shape corresponds to galaxies and accretion discs), usually, no-z approximation is used. Some of the partial derivatives are changed by the algebraic expressions, and the solenoidality condition is taken into account as well. The field generation is restricted by the equipartition value and saturates if the field becomes comparable with it. From the point of view of mathematical physics, they can be characterized as stable points of the equations. The field can come to these values monotonously or have oscillations. It depends on the type of the stability of these points, whether it is a node or focus. Here, we study the stability of such points and give examples for astrophysical applications.

scholarly journals Robust anomalous metallic states and vestiges of self-duality in two-dimensional granular In-InOx composites

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Xinyang Zhang ◽  
Bar Hen ◽  
Alexander Palevski ◽  
Aharon Kapitulnik
Keyword(s):  
Magnetic Field ◽  
Metallic Phase ◽  
Broadband Noise ◽  
Two Dimensional ◽  
Conventional Theory ◽  
Logarithmic Divergence ◽  
Self Duality ◽  
Low Field ◽  
Wide Range ◽  
Low Temperature Resistance

AbstractMany experiments investigating magnetic-field tuned superconductor-insulator transition (H-SIT) often exhibit low-temperature resistance saturation, which is interpreted as an anomalous metallic phase emerging from a ‘failed superconductor’, thus challenging conventional theory. Here we study a random granular array of indium islands grown on a gateable layer of indium-oxide. By tuning the intergrain couplings, we reveal a wide range of magnetic fields where resistance saturation is observed, under conditions of careful electromagnetic filtering and within a wide range of linear response. Exposure to external broadband noise or microwave radiation is shown to strengthen the tendency of superconductivity, where at low field a global superconducting phase is restored. Increasing magnetic field unveils an ‘avoided H-SIT’ that exhibits granularity-induced logarithmic divergence of the resistance/conductance above/below that transition, pointing to possible vestiges of the original emergent duality observed in a true H-SIT. We conclude that anomalous metallic phase is intimately associated with inherent inhomogeneities, exhibiting robust behavior at attainable temperatures for strongly granular two-dimensional systems.

Sign in / Sign up

Export Citation Format

Share Document