Fabrication method, dielectric properties, and electromagnetic absorption performance of high alumina fly ash-based ceramic composites. Issue 15 (1st August 2022)

• Record Type: Journal Article
• Authors: Ayeni, Joshua Olatunji; Ma, Shuhua; Wang, Xiaohui; Hou, Xuan
• Is Part Of: Ceramics international. Volume 48:Issue 15(2022)
• Page Start: 21309
• Page End: 21323
• Publication Date: 2022-08-01
• Subjects: Fly ash -- Sintering -- Mullite-Al2O3-SiC composites -- Dielectric properties -- EM absorption Performance; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2022.04.063
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: Mullite-Al2 O3 -SiC composites were in-situ synthesized through carbothermal reduction reaction of fly ash (FA) with a high alumina content and activated carbon (AC). The effects of sintering temperature, holding time, and amount of AC on the β-SiC yield, microstructure, dielectric properties, and electromagnetic (EM) absorption performance of the composites in the 2–18 GHz frequency range were studied. The results show that increasing the AC improves the porosities of the composites, with the highest porosity of 56.17% observed. The β-SiC yield varies considerably as the sintering parameters were altered, with a maximum yield of 23% achieved under conditions of 12 wt% AC, 1400 °C sintering temperature, and 3 h holding time. With a thickness of 3.5 mm, this composite has excellent EM absorption performance, exhibiting a minimum reflection loss (RLmin ) of -51.55 dB at 7.60 GHz. Significantly, the maximum effective absorption bandwidth (EAB) reaches 3.39 GHz when the thickness is 3.0 mm. These results demonstrate that the composite prepared under ideal conditions can absorb 99.99% of the waves passing through it. Because of the interfacial polarization, conductive loss, and impedance matching of the heterostructure, the synthesized mullite-Al2 O3 -SiC composites with densities ranging from 1.43 g/cm 3 to 1.62 g/cm 3 demonstrate outstanding EM attenuation capabilities. Therefore, this study presents a remarkable way of utilizing fly ash to fabricate inexpensive, functional ceramic materials for EM absorption applications.