“…[217] However, metamaterials fabrication using thermal spray techniques are poised to make a huge impact primarily because they can shape EM radiations in ways like other materials and methods or better, as demonstrated in some of the pioneering work. [77,82,218,219] The thermal spray coating technique can be a viable method to design surface structures to synthesize newer category of metamaterials. It may be noted that metamaterials gain their properties not from their composition, but from engineered and designed artificial structures.…”
Section: Low-observable Metamaterial and Energy Conversion Functions ...mentioning
This review aims to consolidate scattered literature on thermally sprayed coatings with nonionizing electromagnetic (EM) wave absorption and shielding over specific wavelengths potentially useful in diverse applications (e.g., microwave to millimeter wave, solar selective, photocatalytic, interference shielding, thermal barrier‐heat/emissivity). Materials EM properties such as electric permittivity, magnetic permeability, electrical conductivity, and dielectric loss are critical due to which a material can respond to absorbed, reflected, transmitted, or may excite surface electromagnetic waves at frequencies typical of electromagnetic radiations. Thermal spraying is a standard industrial practice used for depositing coatings where the sprayed layer is formed by successive impact of fully or partially molten droplets/particles of a material exposed to high or moderate temperatures and velocities. However, as an emerging novel application of an existing thermal spray techniques, some special considerations are warranted for targeted development involving relevant characterization. Key potential research areas of development relating to material selection and coating fabrication strategies and their impact on existing practices in the field are identified. The study shows a research gap in the feedstock materials design and doping, and their complex selection covered by thermally sprayed coatings that can be critical to advancing applications exploiting their electromagnetic properties.
“…[217] However, metamaterials fabrication using thermal spray techniques are poised to make a huge impact primarily because they can shape EM radiations in ways like other materials and methods or better, as demonstrated in some of the pioneering work. [77,82,218,219] The thermal spray coating technique can be a viable method to design surface structures to synthesize newer category of metamaterials. It may be noted that metamaterials gain their properties not from their composition, but from engineered and designed artificial structures.…”
Section: Low-observable Metamaterial and Energy Conversion Functions ...mentioning
This review aims to consolidate scattered literature on thermally sprayed coatings with nonionizing electromagnetic (EM) wave absorption and shielding over specific wavelengths potentially useful in diverse applications (e.g., microwave to millimeter wave, solar selective, photocatalytic, interference shielding, thermal barrier‐heat/emissivity). Materials EM properties such as electric permittivity, magnetic permeability, electrical conductivity, and dielectric loss are critical due to which a material can respond to absorbed, reflected, transmitted, or may excite surface electromagnetic waves at frequencies typical of electromagnetic radiations. Thermal spraying is a standard industrial practice used for depositing coatings where the sprayed layer is formed by successive impact of fully or partially molten droplets/particles of a material exposed to high or moderate temperatures and velocities. However, as an emerging novel application of an existing thermal spray techniques, some special considerations are warranted for targeted development involving relevant characterization. Key potential research areas of development relating to material selection and coating fabrication strategies and their impact on existing practices in the field are identified. The study shows a research gap in the feedstock materials design and doping, and their complex selection covered by thermally sprayed coatings that can be critical to advancing applications exploiting their electromagnetic properties.
“…Because thermal stability has become the basis for further development of microwave absorption materials, especially in the aircraft, the nozzles, and nose cones of supersonic jets, some experts are researching high-temperature metamaterials, in hopes that metamaterials would still be found with broadband and strong absorption under high temperature. [14][15][16][17] Li et al used conductive TiB 2 squares as unit cells and obtained an absorptivity of more than 95% at an absorption frequency over a wide temperature range. [18] Shao et al designed a metamaterial absorbing coating with a dielectric loss layer of Al 2 O 3 and TiC and a metasurface of NiCrAlY that achieved RL < À5 dB at a frequency range of 8-12 GHz at 800 °C.…”
Excellent thermostable performance is the basis for the further development of microwave absorbing materials in the field of military stealth. Herein, a high‐temperature metamaterial absorber (HMA) with high impedance patterns (multi‐octagonal‐rings), two quartz (SiO2) layers, and a metallic ground film is designed and simulated. The optimal structural parameters are obtained by optimizing the circuit parameters and the size of HMA. The interaction of electric and magnetic resonance in multioctagonal rings results in a wide absorption bandwidth and excellent absorption performance. The experimental results show that the structure has good impedance matching performance, and the effective absorption bandwidth (−10 dB) (EAB) of the structure can reach 10.6 GHz from room temperature to 700 °C under the combined effect of resonance loss and ohmic loss.
“…combined a coating made of Al 2 O 3 and TiC with a square-circular periodic structure prepared using NiCrAlY and achieved RL values below À5 dB at a frequency range of 8-12 GHz at 800 C. [29] Since then, their research group adopted Al 2 O 3 coating as the intermediate layer and printed FSS on its surface with high-temperature conductive ink. The results exhibited an RL < À5 dB over the entire Ku band at 800 C. [30] Li et al used conductive TiB 2 squares as unit cells and obtained an absorptivity of more than 95% at an absorption frequency over a wide temperature range. [31] Qiao et al prepared a conductive paste by mixing graphite microflakes with sodium silicate and then printed a 0.01 mmthick square-ring FSS layer on the quartz glass using screen printing.…”
Section: Introductionmentioning
confidence: 99%
“…The results exhibited an RL < −5 dB over the entire Ku band at 800 °C. [ 30 ] Li et al used conductive TiB 2 squares as unit cells and obtained an absorptivity of more than 95% at an absorption frequency over a wide temperature range. [ 31 ] Qiao et al prepared a conductive paste by mixing graphite microflakes with sodium silicate and then printed a 0.01 mm‐thick square‐ring FSS layer on the quartz glass using screen printing.…”
A broadband metamaterial absorber (MA) with high‐temperature resistance is designed and fabricated using a regular octagonal ring‐cross structure as a frequency‐selective surface (FSS). A high‐temperature conductive paste and SiO2 are used as the FSS raw materials and middle layer, respectively. Simulation and experimental results show that the absorber reaches a reflection loss below −5 dB at the 5.17–18 GHz range with normal incidence at room temperature. The measured values are in good agreement with the simulation results. At 800 °C, the absorption bandwidth expands to 13.3 GHz (4.72–18 GHz). The equivalent impedance of the absorber is obtained using an inversion method to qualitatively explain its working mechanism. The electric energy density, magnetic energy density, and surface current at the resonance frequency provide an intuitive understanding of the power loss of the structure. Comprehensive analysis illustrates that the main absorption mechanisms of the high‐temperature broadband MA (HBMA) are ohmic and resonance losses.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.