Mechanical and adhesive properties of graphene-coated thermoset and thermoplastic aircraft composite materials by physical vapor deposition technology

Abstract

The remarkable properties of graphene have found widespread application across various fields, particularly in enhancing functional properties of materials. This study investigates the effects of graphene coating on thermoplastic polyphenylene sulfide (PPS) and thermoset epoxy matrix carbon-reinforced (CF) composites, with and without peel ply treatment. Graphene was applied using a thermionic vacuum arc system as physical vapor deposition technique. Characterization included contact angle measurement, ultraviolet–visible spectroscopy, atomic force microscopy, Fourier-transform infrared (FTIR) spectroscopy, cross-cut adhesion tests, and thermal imaging. The results showed that graphene coating increased the water contact angle of thermoset composites but had no significant effect on PPS composite. FTIR analysis revealed chemical changes on the surface of composite materials coated by graphene. Additionally, graphene coating did not enhance adhesion strength in thermoplastic composites, as both coated and uncoated composites exhibited a GT5 adhesion grade. However, thermoset composites, whether uncoated or graphene-coated, consistently achieved the highest adhesion grade (GT0), indicating stable adhesion properties regardless of surface treatment. Additionally, thermal camera measurements demonstrated that graphene, combined with low emissive paint, reduced the emissivity of the epoxy composite from 0.95 to 0.78 and the PPS composite from 0.90 to 0.83. The mean values of the Z-height of the filament were measured as to be 100 nm, 90 nm, and 45 nm for epoxy/CF-peel ply, epoxy/CF, and PPS/CF, respectively. Refractive index of the samples was found as 2 and 2.7 for epoxy and PPS/CF composite, respectively. The mean contact angle values were measured as 100°, 94° and 74° after the graphene coating for epoxy/CF-peel ply, epoxy/CF, and PPS/CF composite, respectively. These findings suggest that graphene coating can enhance the thermal performance of thermoset composites without significantly altering adhesion properties.