Microwave Absorbing Properties of Epoxy-SiO2-Fe3O4 Hybrid Coatings on Plasma Electrolytic Oxidation-Treated Aluminum 6061

Irma Sianipar; Nur Asriyani; Muhammad Prisla Kamil

doi:10.23960/jemit.481

Authors

Irma Sianipar Departement of Physics, Faculty of Mathematic and Natural Sciences, Defense University, IPSC Sentul Bogor
Nur Asriyani Departement of Physics, Faculty of Mathematic and Natural Sciences, Defense University, IPSC Sentul Bogor
Muhammad Prisla Kamil Research Center for Advanced Materials, National Research and Innovation Agency (BRIN), South Tangerang, Banten, 15314

DOI:

https://doi.org/10.23960/jemit.481

Keywords:

Aluminum 6061, Plasma Electrolytic Oxidation, Hybrid Coating, Reflection Loss, Vector Network Analyzer.

Abstract

The escalation of radar detection technology has driven an urgent need for microwave-absorbing materials in stealth technology applications. This study investigates the microwave absorption capabilities of an Epoxy-SiO2-Fe3O4 hybrid composite coating applied to Aluminum 6061 substrates treated with Plasma Electrolytic Oxidation (PEO). The incorporation of 5 g/L malonic acid during the PEO process produced an oxide base layer with a thickness of 5.14 +/- 0.89 um, featuring microporous characteristics that facilitate a mechanical interlocking mechanism for the composite layer. Variations in functional filler compositions (S, F, SF1, SF2, and SF3) were exclusively tested using a Vector Network Analyzer (VNA) across the X-band frequency range (8-12 GHz). The results indicated that all samples exhibited resonance peaks within the 8.7-9.26 GHz range. The most significant absorption was achieved by sample S (100% SiO2) with a Reflection Loss (RL) value of -2.34 dB at 9.26 GHz, followed by sample SF3 (75% SiO2 : 25% Fe3O4) with an RL value of -1.91 dB at 9.02 GHz. This performance demonstrates the dominance of the dielectric loss mechanism at high frequencies, while the addition of Fe3O4 plays a strategic role in modifying magnetic permeability to optimize impedance matching. Although the RL values have not yet reached the technical threshold of -10 dB due to single-coat thickness limitations, the integration of PEO and functional hybrid layers successfully reduced microwave reflection intensity systematically on conductive metal surfaces.

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