Effect of Surface Treatment and BN Content on the Mechanical Properties of Aluminum Laminates Reinforced with Glass Fiber and Epoxy Resin

Abstract

Al laminates are widely used in various applications due to their light weight, corrosion resistance, and good electrical conductivity. In this work, aluminum laminates were reinforced with glass fibers and a boron nitride (BN) epoxy resin. Different concentrations of BN (0, 0.3, 0.6, 0.9, and 1.2 wt.%) were incorporated into the epoxy matrix. The laminates were prepared using a vacuum infusion process (VIP) technique. The addition of BN significantly improved the thermal conductivity of the composites. To further improve the interfacial adhesion between the aluminum alloy sheets and the composite layers, plasma surface treatment was applied to the 6061-T6 aluminum alloy sheets. Plasma surface treatment is a well-known technique that can modify the surface properties of materials, including roughness, wettability, and chemical functionality. By introducing surface roughness and functional groups, plasma treatment can improve adhesion between dissimilar materials. After plasma treatment, the surface morphology and composition of the aluminum alloy sheets were analyzed using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy with energy dispersive spectrometry (SEM-EDS). XPS provides information about the chemical composition and bonding state of the surface, while SEM-EDS provides a detailed view of the surface morphology and elemental distribution. Surface roughness and wettability were measured using a surface roughness tester and a contact angle goniometer. The Al/GF/BN/EP laminates were prepared using a thermoforming technique. Mechanical properties including peel, interlaminar shear, tensile, and flexural strength were evaluated. The laminates prepared by plasma surface treatment showed improved mechanical properties with increasing BN concentration up to 0.9 wt.%. This improvement can be attributed to the synergistic mechanism of mechanical and chemical bonding between the metal layer and the composite layer, which is facilitated by the increased surface roughness and the presence of functional groups (C–N and C=N).