Electromagnetic wave absorbing properties of Cr₂AlB₂ powders and the effect of high‐temperature oxidation

Abstract

The electromagnetic (EM) wave absorbing properties of Cr2AlB2 powders and those after high‐temperature oxidation were investigated. Coupling of magnetic and dielectric loss enables Cr2AlB2 with good absorption properties. The minimum reflection loss (RL) value is −44.9 dB at 8.5 GHz with a thickness of 2.7 mm, and the optimized effective absorption bandwidth (EAB) is 4.4 GHz (13.0‐17.4 GHz) with a thickness of 1.6 mm. After oxidation at 750, 900, and 1000°C for 2 h, the minimum RL values, respectively, are −23.9 dB (17.5 GHz, 1.5 mm), −41.4 dB (16.5 GHz, 1.5 mm), and −39.5 dB (8.0 GHz, 3.0 mm); and the corresponding EAB values, respectively, are 3.8 GHz (13.6‐17.4 GHz, 1.7 mm), 4.1 GHz (13.5‐17.6 GHz, 1.6 mm), and 4.4 GHz (13.0‐17.4 GHz, 1.7 mm). With an absorber thickness of 1.5‐4.0 mm, the EAB with a RL value of less than −10 dB can be tuned in a broad‐frequency range 5.0‐18.0 GHz, which basically covers C (4‐8 GHz), X (8‐12 GHz), and Ku (12‐18 GHz) bands. These results demonstrate that Cr2AlB2, as a high‐efficient and oxidation‐resistant absorber, is a promising candidate for microwave absorption applications and can retain good EM wave absorbing properties after high‐temperature oxidation.

Defect‐Engineered Graphene/Si3N4Multilayer Alternating Core‐Shell Nanowire Membrane: A Plainified Hybrid for Broadband Electromagnetic Wave Absorption

“…The EAB of C2 slightly declines after oxidation at 1000 °C for 1 h, and the EAB retention ratio (the ratio of the EAB after oxidation to the EAB before oxidation) of C2 is 93%. Compared with the performance of other ceramic absorption materials [21,[63][64][65][66] (Figure 7c), C2 achieves significantly better oxidation resistance and demonstrates a higher EAB retention ratio. Therefore, the unique structure of alternating DG cores and Si 3 N 4 shells shows great promise for enabling high-temperature EMW absorption.…”

Entropy‐Driven Morphology Regulation of MAX Phase Solid Solutions with Enhanced Microwave Absorption and Thermal Insulation Performance

“…i) The electromagnetic wave absorption performance of (VTiCrMo) 2 GaC in C band; comparison of electromagnetic wave absorption performances: j) among as-prepared MAX phases and k) (VTiCrMo) 2 GaC with other MAX phases absorbers. [44][45][46][47][48][49][50][51][52][53][54] with the (11_00) plane. The atomic discrete distribution maps (Figure 2i,j) show that the atomic spacings along the x and y directions are 0.607 and 0.508 Å, respectively, confirming the formation of a homogeneous solid solution.…”

“…The reflection loss value, 2D color maps of as-prepared MAX phases/paraffin composites: a,e) V 2 GaC, b,f) (VTi) 2 GaC, c,g) (VTiCr) 2 GaC,and d,h) (VTiCrMo) 2 GaC. i) The electromagnetic wave absorption performance of (VTiCrMo) 2 GaC in C band; comparison of electromagnetic wave absorption performances: j) among as-prepared MAX phases and k) (VTiCrMo) 2 GaC with other MAX phases absorbers [44][45][46][47][48][49][50][51][52][53][54].…”

High-Temperature Dielectric and Microwave Absorption Property of Atmospheric Plasma Sprayed Al2O3-MoSi2-Cu Composite Coating

“…With the rapid development of radar detection technology, absorbing materials have attracted more and more attention, especially high-temperature absorbing materials. The commonly used dielectric materials include Ti 3 SiC 2 [1], SiC f [2], and Al 2 O 3 -TiC [3], and the magnetic materials include Fe 3 Si [4], Cr 2 AlB 2 [5], Fe@MoS 2 [6], etc. The absorbing materials include SiCN(CNTs) [7] and SiCO@BN [8], and the absorbing coatings include La 0.6 SrFeO 3 -δ/MgAl 2 O 4 [9], TiC-Al 2 O 3 /Silica [10], etc.…”