Ferrite Rubber Research Articles

Shielding effectiveness of multilayer laminate of aluminum metal matrix and micro absorbing materials

Shielding blocks are widely used to protect sensitive electronic components in defense and medical equipment. In many circumstances, acquiring shielding effectiveness is insufficient, with shielding effectiveness having higher priority if the material possesses mechanical characteristics. To achieve the required electromagnetic shielding effectiveness and mechanical properties such as tensile strength and hardness, a laminate sheet with Al6061 material and micro absorbing materials such as MNZC ferrite rubber composite, Ca-NiTi hexaferrite composites, and Carbonyl iron is preferred in the current work. The total work organized as•Selection of the aluminum metal matrix and micro absorbing material.•Finding the electrical parameters using the vector network analyzer (VNA) using Transmission/Reflection method.•The shielding performance was evaluated for different laminate thicknesses at the X-band.•The material mentioned above can be used as a shielding building block in aeronautical applications and near sensitive medical equipment.

Evaluation of molecular transport mechanism and interfacial interactions in doped ferrite rubber composites

Nickel ferrites (NIFs) come under the class of soft ferrites or transformer ferrites, which are highly demanding in the electronics industry and possess usual low conductivity and ferromagnetic properties, which results in decreased eddy current losses, good electrochemical stability, catalytic action, and abundance in nature. We discuss the synthesis, characterization, and impact of synthesized NIF fillers on the mechanical and solvent transport characteristics of rubber composites. Doped ferrite composites made of natural rubber and nitrile rubber were cured at various temperatures, and the solvent swelling properties of composites containing differently doped NIFs were examined in aromatic solvents like toluene. Properties of both rubber composites were examined, including their morphology, solvent uptake, diffusion coefficient, transport mechanism, and thermal stability. Natural rubber composites found to have better swelling properties than that of nitrile rubber composites. The solvent uptake was reduced with increase in filler loading also, the increase in sorption temperature increases the swelling rate in both systems. Theoretical calculations and modelling clearly state that the diffusion mechanism is due to the polymer swelling as well as polymer relaxation.

Tunable Metamaterial Absorber Using Ferromagnetic Resonance

We simulated a study on a tunable metamaterial absorber using ferrite rubber as a dielectric substrate with ferromagnetic properties. The proposed structure employs ferromagnetic resonance, which utilizes the coupling of an applied magnetic field and an incident electromagnetic wave. As the magnitude of the applied magnetic field increases, it can be seen that the absorption peak moves to a higher frequency. The adjustment of the absorption frequency using the proposed method is expected to be applied to various fields such as sensors, electronic devices and 5G communication antennas.

Development of Co0.7Ca0.3Fe2O4-EPDM nanocomposite for microwave application: Their rheometric behavior, surface topography and electromagnetic parameters

Flexible magnetic nanocomposite materials were prepared by incorporating cobalt/calcium ferrite nanoparticles in the ethylene propylene diene monomer (EPDM) rubber matrix. In this work, microwave characterization of 50% Co0.7Ca0.3Fe2O4 and 50% EPDM nanocomposite has been performed. Ferrite–rubber nanocomposites are important, as they are convenient for adaptive instruments wherein reflection loss (S11) and attenuation (S21) are substantial parameters. The structural characterization of the investigated nanocomposite was explored using X-ray diffraction, atomic force microscopy (AFM), Raman spectroscopy, and scanning electron microscopy (SEM). The average crystallite size of the nanocomposite was obtained at 16.52 nm. The vector network analyzer was incorporated to measure electromagnetic and scattering parameters (S) of the nanocomposite sample placed in the rectangular waveguide. There is an observation of low S11 (reflected signal) in the low-frequency regime and it increases non-monotonically with the corresponding increase in frequency. The microwave signal suffers from minimum attenuation (S21) while passing through the nanocomposite sample and remains less than −3 dB almost along with the entire test frequency range. The low magnetic and dielectric loss in the nanocomposite is in agreement with the S21 parameter as well as low coercivity, which makes it a suitable candidate for low loss application in wireless communication.

Synthesis and Characterization of EPDM/Ferrite Nanocomposites

Ferrite–rubber composites are important, as they are convenient for adaptive instruments where hardness and coercivity are substantial parameters. The structural characterization of the 50Co0.7Ca0.3Fe2O4/50 ethylene propylene diene monomer nanocomposites was carried out using X-ray diffraction, scanning electron microscope and the energy-dispersive X- ray spectroscopy. The obtained average crystallite size is 16.5 nm. For the investigated rubber magnetic nano composites, new and unexpected mechanical, magnetic and rheological properties can be obtained. Mechanical properties of the studied samples are evaluated. The composites showed the behavior of perfect coalescence between the ferrite nanoparticles and the rubber. The accomplished data indicates that nanoferrite samples prolong not only appropriate magnetic properties to the composites, but also strengthen the rubber matrix. The originality of this study is accomplished through emphasizing the magnetization of EPDM and to accentuate the mechanical properties of the studied nanocomposites. The obtained data makes the investigated composites highly applicable in current and future technology across numerous disciplines.

Plasma characteristics and target erosion profile of racetrack-shaped RF magnetron plasma with weak rubber magnets for full circular target utilization

Abstract We have developed the racetrack-shaped RF magnetron plasma with weak rubber magnets (ferrite and neodymium) for the full utilization of the circular target and the reduction of the magnet weight. The magnetic field simulations are analyzed for the ferrite rubber magnets, the neodymium rubber magnets, and the neodymium rubber magnets including the neodymium metal magnets. The magnetic flux density indicates a mountain like profile between the magnets, having a maximum for the neodymium rubber and metal magnets. It is found that the ion flux to the target has a peak in the gap between two rubber magnets and the value remarkably increases with the addition of neodymium metal magnets. The erosion of the circular copper target, with 100 mm in diameter, has been studied by rotating the racetrack-shaped RF magnetron plasma for the neodymium rubber magnets including the neodymium metal magnets. It is seen that radial profile of the erosion depth keeps roughly constant until r = 20 mm and then decreases gradually away from the center for RF power of 40 W, Ar gas pressure of 2 Pa and sputtering time of 4 h. The target utilization is approximately 72% estimated from the erosion profile.

Broadband Ni$_{\rm x}$Zn$_{0.8 - {\rm x}}$Cu$_{0.2}$Fe$_{2}$O$_{4}$ Electromagnetic Absorber for 1 GHz Application

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> Ni<formula formulatype="inline"><tex Notation="TeX">$_{\rm x}$</tex> </formula>Zn<formula formulatype="inline"><tex Notation="TeX">$_{0.8 - {\rm x}}$</tex></formula>Cu<formula formulatype="inline"><tex Notation="TeX">$_{0.2}$</tex> </formula>Fe<formula formulatype="inline"><tex Notation="TeX">$_{2}$</tex> </formula>O<formula formulatype="inline"><tex Notation="TeX">$_{4}$</tex> </formula> ferrites with various composition <formula formulatype="inline"> <tex Notation="TeX">$({\rm x} = 0.45 \hbox{--} 0.79)$</tex></formula> were synthesized by the coprecipitation method for broadband and electromagnetic absorbing characteristics. Saturation magnetization decreased as the Ni content increased, while coercivity was elevated. It was found that calculated reflection loss and fractional bandwidth (FBW) changed with the matching thickness and chemical composition of the ferrite. Minimum reflection loss (RL) of <formula formulatype="inline"><tex Notation="TeX">${-}$</tex></formula>47.05 dB and FBW of 105% were observed at 1 GHz for Ni<formula formulatype="inline"><tex Notation="TeX">$_{0.45}$</tex></formula>Zn<formula formulatype="inline"><tex Notation="TeX">$_{0.35}$</tex></formula>Cu<formula formulatype="inline"><tex Notation="TeX">$_{0.2}$</tex></formula>Fe<formula formulatype="inline"><tex Notation="TeX">$_{2}$</tex></formula>O<formula formulatype="inline"><tex Notation="TeX">$_{4}$</tex> </formula>, which are competitive to those of conventional ferrite and ferrite rubber composite absorbers. </para>

Effect of Carbon Black on the Mechanical and Dielectric Properties of Rubber Ferrite Composites

Nanoparticles of nickel ferrite are synthesised by sol-gel technique. They are then characterised by X-ray diffraction technique (XRD) and Vibrating sample magnetometer (VSM). Precharacterised ultra fine nickel ferrite is then incorporated in ethylene propylene diene rubber (EPDM) according to a specific recipe. The prepared rubber ferrite composites (RFCs) are found to have appreciable mechanical and dielectric properties. Addition of appropriate amount of carbon black to RFCs substantially improves its dielectric properties. Variation of dielectric properties of RFCs with frequency is studied in the frequency range 0.1-8 MHz and is found to vary in accordance with MaxwellWagner interfacial polarisation. dc conductivity of the RFCs is also measured and correlated with filler loading.

Permittivity Characteristics in the X- and S-Band Frequencies of Microwave Absorbers Based on Rubber Ferrite Composites

Fine particles of nickel ferrite are synthesized by the sol-gel technique and characterized by the X-ray diffraction method. These materials are incorporated in ethylene propylene diene rubber (EPDM) according to a specific recipe for various loadings. The rubber ferrite composites (RFCs) thus obtained have several applications, such as microwave absorbers, EMI shielding materials, etc. In the present study, microwave attenuation and dielectric properties of RFCs are studied in the X- and S-band frequencies. Real and imaginary parts of the dielectric permittivity are determined by cavity perturbation method. Dielectric permittivity in X-band frequency, based on Maxwell—Garnet equation is calculated and presented here.

Physicomechanical and Magnetic Properties of Neoprene Based Rubber Ferrite Composites

Fine (approximately 18 nm) particles of nickel ferrite were synthesized by the sol-gel technique, and their structural properties were evaluated by X-ray diffraction. Neoprene-based rubber ferrite composites were prepared by incorporating these nickel ferrite powders in the rubber matrix according to a specific recipe. The cure characteristics were analyzed, and the samples were molded into particular shapes whose properties were determined according to ASTM standards. Magnetization studies were carried out using a Vibrating Sample Magnetometer. This study indicates that neoprene rubber-based flexible magnets with desired magnetic properties and appropriate mechanical properties can be prepared by incorporating an adequate amount of nanoscale nickel ferrite particles within the rubber matrix.

Ni-Cu-Zn Ferrite의 복합형 전파흡수체 특성 연구

복합 전파흡수체로 사용할 Ni-Cu-Zn ferrite는 공침법을 사용하여 제조 하였고,제조 시편의 물리적 특성 및 전파흡수특성은 소결온도 변화에 따라 고찰하였다. Ni-Cu-Zn ferrite의 스피넬 구조는 XRD pattern을 통하며 확인하였다. 소결온도가 <TEX>$1100^{\circ}C$</TEX>에서 흡수 능력도 좋아짐을 알 수 있었으며, 소결된 페라이트의 초투자율은 평균 50 정도로 나타났다. <TEX>$Ni_{0.7}Cu_{0.2}Zn_{0.1}Fe_2O_4$</TEX> 조성에서 소결 온도가 <TEX>$1100^{\circ}C$</TEX> 일 때가 복합 전파흡수체로 사용할 조성임을 확인할 수 있었으며, 그 결과 복합 전파흡수체에서 사용할 수 있다고 사료된다. Ni-Cu-Zn ferrites were prepared by the co-precipitation. Physical properties and Microwave absorbing properties were investigated in Ni-Cu-Zn ferrite for the aim of microwave absorbers. From the analysis of X-ray diffraction patterns, we can see that all the particles have only a single phase spinel structure. The loss factor was maximum at sintering temperature <TEX>$1100^{\circ}C$</TEX>. The initial permeability of sintered ferrite obtained was an average of 50. We found that the <TEX>$(Ni_{0.7}Cu_{0.2}Zn_{0.1}O)_{1.02}(Fe_2O_3)_{0.98}$</TEX> can be used in ferrite rubber composite microwave absorber when sintering temperature at <TEX>$1100^{\circ}C$</TEX>.

Evaluation of the Magnetic and Mechanical Properties of Rubber Ferrite Composites Containing Strontium Ferrite

Ceramic strontium ferrites belonging to the M-type hexagonal ferrites have been prepared by the ceramic technique. They were then characterized using x-ray diffraction method and incorporated into natural rubber (NR) matrix according to a specific recipe to produce rubber ferrite composites (RFC). RFC are magnetic polymer composites, which have a variety of applications as flexible magnets, pressure/photo sensors, and microwave absorbers. The mechanical properties were studied using a universal testing machine (UTM) and the magnetic properties were studied using a vibrating sample magnetometer (VSM). The present study indicates that flexible magnets having appropriate mechanical strength and magnetic properties can be prepared by the incorporation of strontium ferrite in elastomer matrixes. The magnetic measurements indicated that composites having appreciable coercivity (Hc) and saturation magnetization (Ms) could be synthesized by the incorporation of the ceramic ferrites in natural rubber matrix. It has also been found that the coercivity of the ceramic ferrite and the rubber ferrite composites remained almost the same.

Detection of harmonic ultrasound scattered from microbubbles with ultrasound transducer for harmonic imaging having double peak type frequency characteristics

Ultrasound transducer with double peak type frequency characteristics was proposed for contrast harmonic imaging. It can transmit ultrasound in a fundamental mode and receive the second harmonic signal from tissues or microbubble contrast agents. The transducer has been made by stacking a piezoelectric ceramic vibrator and a subvibrating plate on the backing block made of ferrite rubber with an acoustic absorption. Glass subvibrating plate (0.4 mm thick) was found suitable for this ultrasound transducer. The second harmonic component contained in the scattered waves from microbubbles coated with surfactant was detected experimentally with a trial manufactured ultrasound transducer with double peak type frequency characteristics. The results confirmed that the transducer can transmit ultrasound to microbubbles, excite the second harmonic component based on the nonlinear behavior of microbubbles and detect the second harmonic component. It was also found that the second harmonic component can be detected most effectively when burst waves with cycles from 5 to 10 were applied to the ultrasound transducer.

A theoretical study on suppression of scattering by a perfectly conductive cylinder array

AbstractIn this paper, TV ghosts produced by the metal suspension cables of a large suspension bridge are studied. Improvement of the D/U ratio at the receiving point is investigated. It is demonstrated by calculations and experiments that by loading the metal cylinders with a cylindrical ferrite, the relative scattering intensity in the 0 to 90° range in the horizontal plane can be reduced. By loading cylindrical dielectric materials the relative scattering intensity can be reduced by about 8 dB, while scattering in other directions increases. Hence, by using a cylindrical absorber made of a combination of a dielectric material and rubber ferrite, suppression of the scattering at more than 90° on one side is investigated. Theoretical calculations of the scattering properties are carried out by means of the multiple multipole program (MMP) method. It is shown that the relative scattering intensity near 120° can be reduced to less than –10 dB without increase of scattering in other directions. It is therefore shown theoretically that the D/U ratio can be improved. © 2001 Scripta Technica, Electron Comm Jpn Pt 2, 84(11): 41–50, 2001

Design of super wideband electromagnetic wave absorber and its characteristics

AbstractBy combining a ferrite‐type electromagnetic wave absorber and a lossy dielectric layer, an electromagnetic wave absorber with a super wideband characteristic can be realized. In this paper, a grid‐type ferrite absorber and a rubber ferrite loaded ferrite multilayered absorber are treated as a ferrite‐type absorber. When a lossy dielectric material is mounted in front of these ferrite‐type wave absorbers, the thickness of a lossy dielectric layer necessary for realization of a return loss of more than 20 dB at any frequency above 30 MHz was computed. It was found that the thickness is much less than that for the lossy dielectric attached to a single layer ferrite. Further, by means of a model experiment in the coaxial tube, the thickness of the lossy dielectric layer was proven to be smaller if a lossy dielectric is combined with the grid‐type ferrite absorber loaded with rubber ferrite.

Widening the bandwidth of ferrite electromagnetic wave absorbers by attaching rubber ferrite

With a view to increasing the bandwidth of ferrite electromagnetic wave absorbers, the reflection characteristics were studied for an absorber made of sintered ferrite loaded with rubber ferrite via an appropriate dielectric layer. First, by means of calculations, it is shown that this structure has a bandwidth wider than that for the sintered ferrite single-layer absorber. Also, the bandwidth of the absorber increases as the permittivity of the dielectric material inserted in between is lower. By loading an appropriately thick rubber ferrite plate via an air layer on a sintered ferrite plate, an absorber can be constructed for which the reflection is less than -20 dB over the frequency range from 30 to 1830 MHz. By loading another air/rubber ferrite pair, an even further increase of the bandwidth is possible. For an existing ferrite single-layer absorber, it is effective for increase of the bandwidth to load the air/rubber ferrite by attaching a sheet resistance on the ferrite surface. Finally, by an experiment, it is shown that a broader bandwidth can be obtained than the ferrite single-layer absorber by loading a rubber ferrite via a low-permittivity layer.

The microwave absorbing and resonance phenomena of Y-type hexagonal ferrite microwave absorbers

The microwave absorbing characteristics and resonance of Y-type hexagonal ferrite–rubber composites were investigated. The complex permeability and permittivity of Ni2−xZnxY ferrite bodies were measured using a network analyzer in the frequency range of 200 MHz–14 GHz. Two types of resonance, the domain wall and the spin rotational resonance, were observed. With a ferrite particle with a diameter of about 1 μm, only spin rotational resonance was observed. The first matching frequency, found in the ferrite–rubber composites, which was higher than that of spin rotational resonance, increased with spin rotational resonance frequency. It was also found that domain wall resonance had no effects on the microwave absorbing characteristics. Based on these findings, it could be concluded that the microwave absorbing characteristics were caused by only one type of resonance, the spin rotational resonance.

DEVELOPMENT OF HIGH DAMPING FERRITE RUBBER BEARING

DEVELOPMENT OF HIGH DAMPING FERRITE RUBBER BEARING

Piezoelectric ultrasonic probe using an epoxy resin and iron carbonyl acoustic matching layer

An ultrasonic probe for an ultrasonic medical diagnostic apparatus which is composed of a piezoelectric vibrator with electrodes attached onto both surfaces thereof and one or two acoustic matching layers which are provided on the surface of one electrode of the piezoelectric vibrator. One of the acoustic matching layers is made of thermosetting resin such as epoxy resin mixed with magnetic material. A backing load member which is made of ferrite rubber or plastic mixed with tungsten powder is provided on the surface of the other electrode of the piezoelectric vibrator. An acoustic lens which is made of silicone rubber may be disposed on the upper acoustic matching layer. The acoustic matching layers may be formed by pouring the materials, thereby to form the ultrasonic probe without an intermedium of a different kind of material on the piezoelectric vibrator.

Effect of doping carbon in an electromagnetic wave absorber rubber ferrite

AbstractFerrite, a ferromagnetic material in the form of sintered ferrite and rubber ferrite, is used for electromagnetic‐wave absorbers. However, there is a certain limit to reducing the thickness of the electromagnetic wave absorber using ferrite. For obtaining thin rubber‐ferrite electromagnetic‐wave absorbers, carbon is added to them and their electromagnetic‐wave absorbing characteristics are examined. The results show that the thickness can be reduced to about 30 percent by adding the order of 1 to 10 percent (volume ratio) of carbon to ferrite. The reduction of the thickness of the absorber also reduces its weight. The mixing of carbon is highly effective in reducing the weight of the absorber, since the specific gravity of carbon is smaller than ferrite. This paper presents the electromagnetic‐wave absorption characteristics of carbon‐added rubber ferrite.