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Description
Radio-frequency (RF) and microwaves (MWs) are widely used owing to their benefits, including rapid transmission speed and broad frequency band. As a result,numerous applications in many different fields, including defense, telecommunications, healthcare, and consumer electronics have emerged.
This work focuses on the synthesis of magnetic functional materials embedded in a polymeric matrix for microwave absorbing purposes. These composite materials are developed for applications in reducing interferences by electromagnetic pollution and mitigating risks to both health and the environment.
The selected materials acting as the functional phase were Fe, Fe3O4, BaFe12-xCuxO19 and CoFe2O4, all in powder form. The synthesis routes used were Coprecipitation and Sol-Gel as wet-chemical methods provide excellent control in particle size and morphology, operating at low temperatures and low-cost. As the polymeric matrix, epoxy resin with specific additives was used. These materials were selected by the excellent magnetic properties, and the additives were chosen to make a stable suspension and give certain thixotropy for the particularity of being able to be sprayed into metal sheets.
Different experimental characterization techniques were applied to the samples. Firstly, XRD analysis for phase identification purposes and to measure the crystallite size of the powder agglomerates. Later, PSD analysis was made to ensure that nano-micro particles were obtained due to the impact of this to the rheological properties of final composite material. Moreover, different volume filling factors (VFF) of reinforced phase were studied.
For electromagnetic properties characterization, the magnetic characterization was performed using a SQUID magnetometer. The measurements consisted of obtaining key parameters such as saturation magnetization, remanent magnetization and hysteresis cycle of each material. In addition, waveguided analysis directly measures the physical constants such as electrical permittivity and magnetic permeability, important because they modify the Reflection Loss (RL) parameter used to determine the efficiency in microwave absorption.
