Preparation of Fe–Si–Al intermetallic alloy and their composite coating for EM absorbing application in 6–18 GHz

摘要

An energy efficient and scalable process has been developed for the preparation of intermetallic Fe–Si–Al alloy particles.The preparation process involves initial homogenization & mechanical activation of elemental metal powders followedby vacuum annealing at elevated temperature ～ 650 ℃. The physical properties of the as synthesized powders wereinvestigated by means of X-ray Diffraction (XRD), Energy Dispersive Xray Flourence (EDXRF),Vibration Sample Magnetometer(VSM), Scanning Electron Microscope (SEM) and Particle Size Analyser. Composite coatings have been prepared bydispersing 30–60 wt% of Fe–Si–Al alloy in polyurethane (PU) resin. The effect of loading of Fe–Si–Al alloy on dielectricand electromagnetic (EM) properties of composites are studied in 6–18 GHz. A suitable formulation (50 wt% Fe–Si–Al)has been identified, wherein, proper combination of dielectric and magnetic loss of coating composite showed optimalmicrowave (MW) absorption in 6–18 GHz. The identified composite coating of thickness ～ 1.6 mm showed maximumReturn Loss (RL) value ～ − 43 dB at 11.9 GHz and the loss values can exceed more than 10 dB within 6.5 to 16 GHz whilevarying thickness of coating from 1.2 to 2.2 mm. In the present study, microwave absorption properties of coatings aremainly credited to dielectric and magnetic loss values of the composites. The Fe-Si-Al filled resin composite with optimalloading of alloy particles can be a promising candidate for microwave absorbing coating applications.