Reflectivity of hybrid microwave absorbers based on NiZn ferrite and carbon black

Dias, Josiane de Castro; Martin, I. M.; Rezende, Mirabel Cerqueira

doi:10.5028/jatm.2012.04032512

Cited by 17 publications

(6 citation statements)

References 12 publications

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“…The arch structure is designed to keep the horn pointing to the center of the specimen under testing. The transmitter and the receiver antennas can be close to each other as long as an absorbing material is positioned between them, to reduce interference between the horns, as illustrated in Dias et al . The reflectivity measurements were performed in the 8.2–12.4 GHz frequency range, at room temperature.…”

Section: Methodsmentioning

confidence: 99%

Glass fiber/carbon nanotubes/epoxy three-component composites as radar absorbing materials

et al. 2015

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The use of micro or nano‐fillers to optimize the properties of epoxy resins has become a common practice. The Carbon nanotubes (CNT) are considered excellent fillers because of their strength, stiffness, thermal conductivity, electrical capacity, and thermal stability, along with large electromagnetic wave absorption capability in the microwave range. In this work, electromagnetic absorption properties and dynamic‐mechanical response obtained with the incorporation of CNT into glass fiber/epoxy composites have been studied. A novel procedure to disperse and deposit CNT onto glass fiber fabrics has been developed to reach high overall content of CNT in the composite (4.15 wt%). Storage modulus increased with the incorporation of CNT, especially when they had also been incorporated into the epoxy, and for higher frequency (3 Hz). The response of the composites to electromagnetic radiation has shown an increasing trend for higher CNT content (up to 2 wt%), reaching an excellent attenuation value of up to −18.3 dB (98.5% of absorption). POLYM. COMPOS., 37:2277–2284, 2016. © 2015 Society of Plastics Engineers

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Section: Methodsmentioning

confidence: 99%

Glass fiber/carbon nanotubes/epoxy three-component composites as radar absorbing materials

et al. 2015

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“…Measurements of different coating formulations applied on aluminum flat plates (l.0 mm thickness) were performed in the X-band frequency range. The attenuation values were − 4 dB for the formulation of polyurethane 49wt%/carbon black 1wt%/ferrite 50wt% [23]. In the current work, a new microwave-absorbent nanocomposite was created with a unique combination and properties suitable for absorption in 2-8 GHz frequency range.…”

Section: Introductionmentioning

confidence: 93%

Preparation and characterization of a flexible microwave absorber based on MnNiZn ferrite (Mn0.1Ni0.45Zn0.45Fe2O4) in a thermoset polyurethane matrix

2020

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In this work, spinel nanoMnNiZn ferrite (Mn 0.1 Ni 0.45 Zn 0.45 Fe 2 O 4) was hosted by a thermoset polyurethane matrix (PU), to produce flexible thin nanocomposite sheets as efficient microwave absorbers. The microwave absorbers of polyurethane nanocomposites were prepared using different loading ratios of MnNiZn ferrite (70%, 75%, and 80wt%). Microwave absorption properties of the nanocomposites were characterized in the range of Sand C-band (2-8 GHz) frequency. Structural and morphological characterizations were performed using X-ray diffractometry (XRD), Fourier-transform infrared spectrophotometer (FTIR), and scanning electron microscopy (SEM). The tensile test was performed to examine the mechanical properties of the molded nanocomposites. The surface hardness was measured using Shore (A) hardness tool. The nanocomposite with 80 wt% loading percent of ferrite in PU at thickness of 5 mm exhibits the best absorption properties and has effective absorption bandwidth (≥ − 10 dB) of 4.28 GHz, with − 29.7 dB minimum reflection loss (RL) at the matching frequency (5.86 GHz) with density of only 2.403 g/cm 3. The experimental results reveal that the microwave absorption properties of the synthesized nanocomposites were improved and reinforced in the case of polyurethane matrix compared to the paraffin wax matrix, through polar-polar interactions and adhesion between the filler and elastomeric matrix depending on their chemical nature. Also, the effect of thermal aging on the performance of the microwave absorption properties of PU-ferrite nanocomposite has been studied. To the best of our knowledge, the use of this cost-effective thermoset polyurethane matrix prepared from PPG, TDI, and castor oil and loaded with ferrite has not been reported before. The effect of polar-polar interactions between the matrix and the ferrite on the microwave absorption characteristics has also been investigated. The high value of reflection loss makes the obtained lightweight and flexible nanocomposite a promising microwave-absorbing material.

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“…When the appropriate setting of the complex parameters of permeability and permittivity is reached we have the impedance matching and the RL is maximal for the material (for a given frequency and a given material thickness) [24].…”

Section: Scanning Electron Microscopy (Semmentioning

confidence: 99%

Electromagnetic, Morphological, and Electrical Characterization of POMA/Carbon Nanotubes-Based Composites

Pinto

Rezende

2017

Journal of Nanomaterials

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This study involves the preparation of conducting composites based on poly(o-methoxyaniline) (POMA) and carbon nanotubes (CNT) and the evaluation of them as radar absorbing materials (RAM), in the frequency range of 8.2–12.4 GHz (X-band). The composites were obtained by synthesis in situ of POMA in the presence of CNT (0.1 and 0.5 wt% in relation to the o-methoxyaniline monomer). The resulting samples—POMA/CNT-0.1 wt% and POMA/CNT-0.5 wt%—were incorporated in an epoxy resin matrix in the proportion of 1 and 10 wt%. FT-IR analyses show that the POMA was successfully synthesized on the CNT surface. SEM analyses show that the synthesized POMA recovered all CNT surface. Electrical conductivity measurements show that the CNT contributed to increase the conductivity of POMA/CNT composites (1.5–6.7 S·cm−1) in relation to the neat POMA (5.4 × 10−1 S·cm−1). The electromagnetic characterization involved the measurements of complex parameters of electrical permittivity (ε) and magnetic permeability (µ), using a waveguide in the X-band. From these experimental data reflection loss (RL) simulations were performed for specimens with different thicknesses. The complex parameters show that the CNT in the composites increased ε and µ. These results are attributed to the CNT network formation into the composites. Simulated RL curves of neat POMA and POMA/CNT in epoxy resin show the preponderant influence of POMA on all RL curves. This behavior is attributed to the efficient CNT recovering by POMA. RL results show that the composite based on 10 wt% of POMA/CNT-0.5 wt% in epoxy resin (9 mm thickness) presents the best RL results (≈87% of attenuation at 12.4 GHz).

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Reflectivity of hybrid microwave absorbers based on NiZn ferrite and carbon black

Cited by 17 publications

References 12 publications

Glass fiber/carbon nanotubes/epoxy three-component composites as radar absorbing materials

Glass fiber/carbon nanotubes/epoxy three-component composites as radar absorbing materials

Preparation and characterization of a flexible microwave absorber based on MnNiZn ferrite (Mn0.1Ni0.45Zn0.45Fe2O4) in a thermoset polyurethane matrix

Electromagnetic, Morphological, and Electrical Characterization of POMA/Carbon Nanotubes-Based Composites

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