Enhancement of Solid Particle Erosion‐Resistance in Carbon‐Fiber Epoxy Composites Using Electrophoretically Deposited Carboxyl Functionalized Graphene on Carbon Fiber

ABSTRACT Carbon fiber reinforced polymer (CFRP) composites exhibit high specific strength and stiffness, making them suitable for applications such as helicopter rotor blades, high‐speed vehicles, missile components and unmanned aerial vehicles (UAVs). These applications may present situations of intense sand erosion and hence the erosion resistance of CFRPs needs to be enhanced, and the use of a strong nano‐filler can help achieve this. In the current study, the carbon fiber‐epoxy interface was modified with variable carboxyl functionalize graphene (G‐COOH) content (0.15, 0.53, 0.8, and 1.1 wt. % relative to the weight of the carbon fiber fabric) using an effective electrophoretic deposition technique and the products deposited were confirmed using X‐ray photoelectron spectroscopy. The G‐COOH‐deposited fabrics were used for composite fabrication through the vacuum‐assisted resin transfer molding (VARTM) technique. All the G‐COOH‐deposited carbon fiber composites showed lower erosive wear rate at 30°, 60° and 90° angles compared to the pristine carbon fiber (PCF) composite. The 0.15 wt. % G‐COOH‐deposited carbon fiber composite exhibited the highest erosion resistance at 30° (28%) and 60° (13%) angles of impingement. In contrast, the 1.1 wt. % G‐COOH‐deposited carbon fiber composite showed the highest erosion resistance/lower wear rate (12%) at 90° angle of impingement among all compositions. The PCF composite showed the poorest erosive wear resistance, with the lowest resistance at 60° and 90° impingement while the 0.8 wt.% composite exhibited the lowest wear resistance among G‐COOH‐deposited composites at all angles. However, the 0.8 wt.% composite exhibited the highest wear resistance of 15% at 30° angle of impingement compared to other angles. The Al 2 O 3 erodent fragments were deposited into the samples with their highest prominence at 90°, particularly in epoxy‐rich regions across all composites. The deposition morphology and erosive failure mechanisms were analyzed using scanning electron microscope (SEM), while the cross‐sectional G‐COOH deposition morphology within the composite was observed using focused ion beam scanning electron microscope (FIB‐SEM). The interphase thickness was measured with energy‐dispersive X‐ray spectroscopy (EDS) carbon line scanning, and G‐COOH at the interphase was identified through Raman intensity mapping. EDS area mapping of the eroded surface, analyzed using the electron beam source of FIB‐SEM, confirmed the presence of higher number of Al 2 O 3 fragments at higher angles compared to lower angles, with a similar trend observed in G‐COOH‐deposited composites. Additionally, the eroded specimens of G‐COOH‐deposited composites exhibited various major failure mechanisms, such as adhered fiber fracture, interphase failure or adhered G‐COOH, and debonding of G‐COOH/epoxy clusters, whereas the PCF composite primarily exhibited fiber debonding, matrix fracture, and fiber fracture as the dominant failure mechanisms.