Carbonyl iron powders as absorption material for microwave interference shielding: A review

Rapid digitalization and technological advancements in the modern era has attracted a different kind of pollution termed as "Electromagnetic Interference (EMI)", which is creating tremendous loss, not only to the working of electronic appliances but also to the human health. Microwaves holds a prominent position in the electromagnetic spectrum due to their diversified applications in broadcast, communication, commercial, household, military and aerospace. Microwave absorption materials (MAM's) play a significant role in absorption of unwanted microwaves thus promoting microwave interference shielding by absorption. Development of MAM's with superior properties like, high absorption, wide band, light weight and thinner body is the present-day requirement and many materials including, dielectric, magnetic and hybrid types are being continuously explored and developed. Carbonyl Iron Powder (CIP) is one such prominent magnetic materials being used in microwave absorption. This review emphasises to elucidate the synthesis of carbonyl iron powder along with various research works performed using pristine CIP as microwave absorption material. Further, modification of CIP in terms of particle size, shape, aspect ratio and morphology by comminution and the effect of powder characteristics on their electro-magnetic properties is discussed. Compounding of CIP by means of coating and/or mixing with other potential dielectric materials like SiO2, MnO, ZnO, SnO2, graphite, carbon black, carbon fiber, carbon nanotubes, etc and their effect on overall shielding property of material is also elucidated. This review also brings out the content of various research works performed using CIP as MAM and various functional benefits than can be achieved by modifying CIP powder characteristics. (C) 2020 Elsevier B.V. All rights reserved.