Synthesis and Microwave Absorption Properties of Fe-Loaded Fly Ash-Based Ceramic Composites

Abstract

To realize the effective recycling of solid waste fly ash (FA) and reduce the preparation cost of microwave absorbent, the Fe-loaded fly ash composites (FeFA) were synthesized using FA. In this study, the FeFA composites were prepared through granulation technology with FA, impregnation with Fe 3+ , and the carbothermal reduction process under different annealing temperatures, during which the Fe particles as main magnetic components were uniformly embedded into the interior and surface of the ceramic matrix. As expected, the FeFA800 composite showed superior microwave absorption (MA) performance, its minimum reflection loss (RL min ) value could reach −40.3 dB when the coating thickness was 2.5 mm and the effective bandwidth reached 4.1 GHz with the coating thickness of 1.5 mm. The attenuation of electromagnetic wave should benefit from the effective impedance matching characteristics and multiple interfacial polarization effects between the different components in the composite. Owing to the facile preparation process, excellent MA performance, and low cost, the FeFA composites with a density of 1.69−1.91 g/cm 3 can be a promising candidate for application in the field of electromagnetic wave absorption and shielding. This work also opens up a way for the comprehensive recovery and utilization of FA.

Data‐driven methodology to realize strong and broadband microwave absorption properties of polymer‐fly ash cenosphere composite

“…However, for lightweight and efficient microwave absorption, hybrid hollow microsphere‐based fillers in polymer composite are advantageous 17–19 . Fly ash cenosphere (FAC), a thermal power plant's solid waste, typically hollow ceramic microsphere, is a waste material in many Asian countries such as India and China 19–24 . FAC is causing many serious environmental problems and human health‐related problems due to insufficient utilization and improper disposal 23,24 .…”

“…Fly ash cenosphere (FAC), a thermal power plant's solid waste, typically hollow ceramic microsphere, is a waste material in many Asian countries such as India and China 19–24 . FAC is causing many serious environmental problems and human health‐related problems due to insufficient utilization and improper disposal 23,24 . Metal and metal oxide coated FAC have been reported for many potential applications such as synthesis of zeolite, mine backfill, lightweight aggregate, road sub‐base, constructions, and sewage disposal, microwave absorption and EM interference (EMI) shielding 20,23,24 .…”

“…FAC is causing many serious environmental problems and human health‐related problems due to insufficient utilization and improper disposal 23,24 . Metal and metal oxide coated FAC have been reported for many potential applications such as synthesis of zeolite, mine backfill, lightweight aggregate, road sub‐base, constructions, and sewage disposal, microwave absorption and EM interference (EMI) shielding 20,23,24 . For example, Li et al reported the minimum RL (RL min ) −15.4 dB for 3 mm thicker 50 wt% loaded barium‐ferrite‐coated FAC loaded paraffin wax 22 .…”

Two‐step preparation of fly ash‐based composites for microwave absorption

“…Thus, it is urgent to design an excellent MA material with the performances of strong absorption, broad frequency range, tiny thickness, and low cost for solving electromagnetic pollution. As is known, an ideal absorber is a hybrid material composed of both magnetic loss and dielectric loss 4,5 . Recently, considerable efforts have been devoted to combining magnetic components with carbon materials to fabricate hybrid composites, 6‐8 which not only can regulate impedance matching, but also improve the attenuation ability.…”

“…As is known, an ideal absorber is a hybrid material composed of both magnetic loss and dielectric loss. 4,5 Recently, considerable efforts have been devoted to combining magnetic components with carbon materials to fabricate hybrid composites, 6-8 which not only can regulate impedance matching, but also improve the attenuation ability. However, it remains a great challenge to prepare these carbon-based materials using a simple and lowcost method.FA, the solid waste, is generated during the combustion of coal in coal-fired power plants.…”