Micro-Helical Ni3fe Chain Encapsulated in Ultralight Mxene/C Aerogel to Realize Multi-Functionality: Radar Stealth, Thermal Insulation, Fire Resistance, and Mechanical Properties

Abstract

Owing to their high porosity, ultralow density, and excellent impedance matching, magnetic carbon aerogels are considered to be a promising microwave absorption (MA) material. However, the inevitable agglomeration of traditional magnetic microspheres in carbon materials makes it difficult to realize perfect electromagnetic synergy. In this study, Ni3Fe alloy particles are first assembled into a micro-helical Ni3Fe chain under ethylene glycol polymerization, which are further wrapped by MXene. Then, carbonyl-amine condensation reaction is used for the in-situ growth of poly-Schiff-base aerogels on the independent caterpillar-like Ni3Fe/MXene. Finally, ultralight TiO2/Ni3Fe/MXene/C (NFMC) aerogels are synthesized through calcination treatment. Benefiting from the electromagnetic synergistic effect of multi-dimensional and multi-component materials, the NFMC-7 aerogel exhibits excellent MA performance with a minimum reflection loss of -61.6 dB at 3.0-mm thickness and an effective absorption bandwidth of 8.16 GHz at 2.77-mm thickness under a low filler loading of 7.6 wt.%. Commercial computer simulation technology is used to verify the strong magnetic and dielectric loss characteristics of Ni3Fe chains. Meanwhile, the radar cross-section (RCS) simulation of NFMC-7 aerogels reveals their excellent radar stealth performance with a maximum RCS reduction value of 20.1 dB·m2 at 0° as well as thermal insulation property with a thermal conductivity of 0.046 W/m·K. Notably, the NFMC-7 aerogel is fire-resistant and can withstand nearly 750 times its own weight without damage, which verifies its practical applicability. Overall, this work establishes an effective strategy to fabricate multi-functional magnetic aerogels, which can serve as lightweight, thin, and strong microwave absorbers with broad absorption bandwidth.

Keywords: Micro-helical Ni3Fe chain, MXene/C aerogel, In-situ grown poly-Schiff-base aerogel, Multi-functional composite material, Electromagnetic synergy, Computer simulation technology.