Multifunctional evaluation of treated cork powder-doped hybrid fiber metal laminates (HFMLs): Mechanical properties,electromagnetic shielding,and X-ray attenuation

Abstract

In this study, hybrid fiber–metal laminates (HFMLs), composed of aluminum, glass fibers, and epoxy resin, were fabricated by incorporating cork powder chemically treated with a 2 wt.% NaOH solution (particle size <200 µm). Three types of laminates were produced with cork contents of 0%, 3%, and 6%, denoted as FML-0, FML-3, and FML-6. Mechanical properties were evaluated through three-point bending and Charpy impact tests. Although the flexural strength and stiffness decreased with the addition of cork, in the Charpy test, the FML-3 laminate showed an improvement in specific absorbed energy of +22.76% on aluminum side and +26.42% on composite layer side. This improvement is attributed to better energy dissipation due to homogeneous dispersion of particles within the epoxy. Electromagnetic shielding effectiveness, related to microwave absorption, was evaluated in the X-band (8–12 GHz) using a vector network analyzer. The FML-3 laminate achieved a reflection loss of −29.18 dB, corresponding to 99.88% attenuation of the incident electromagnetic wave for a thickness of 5.70 mm. X-ray attenuation measurements, performed with tube voltages ranging from 20 to 30 kV, showed an increase in the mass attenuation coefficient with increasing cork content, accompanied by a reduction in density, particularly noticeable for FML-6.