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

• Published in: Journal of the American Ceramic Society 2021-05, Vol.104 (5), p.2213-2224
• Main Authors: Zhang, Haiming, Zhao, Biao, Xiang, Huimin, Dai, Fu‐Zhi, Zhang, Zhili, Zhou, Yanchun
• Format: Article
• Language: English
• Subjects: Absorbers; Cr2AlB2; dielectric and magnetic coupling; Dielectric loss; Electromagnetic radiation; electromagnetic wave absorbing properties; Frequency ranges; layered ternary boride; Magnetic properties; Microwave absorption; Oxidation; Oxidation resistance; Thickness
• ISSN: 0002-7820; 1551-2916
• DOI: 10.1111/jace.17601

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. Microwave absorption properties of Cr2AlB2 powders (A, B) and the Cr2AlB2 powders oxidized at 900°C (C, D).