Optimizing alumina reinforcement in kevlar-epoxy composites: a study on mechanical and tribological enhancements

Abstract Kevlar-reinforced epoxy composites are widely employed in high-performance applications due to their excellent strength-to-weight ratio and impact resistance. However, limitations in wear resistance hinder their use under abrasive conditions. To address this, Alumina (Al2O3) was incorporated as particulate filler at 2%, 4%, and 6% by weight. Composite laminates were fabricated using hand layup followed by compression molding, with a constant Kevlar fiber content of 30 wt%. Mechanical testing was conducted as per ASTM D3039 (tensile), ASTM D790 (flexural), and ASTM D785 (hardness) standards, while wear behavior was evaluated under dry sliding conditions using ASTM G99 with a pin-on-disc setup at 10 N load, 1.5 m/s sliding velocity, and 500 m sliding distance. The addition of 4% alumina yielded optimal performance, resulting in a 28% increase in tensile strength (from 98 MPa to 126 MPa), a 21.6% increase in flexural strength (from 152 MPa to 185 MPa), and a 12.2% increase in hardness (from 82 HRB to 92 HRB) compared to the control. The wear rate was reduced from 3.12 × 10−4 mm3/N·m in the control to 1.89 × 10−4 mm3/N·m at 4% alumina, representing a 39.4% improvement. The coefficient of friction also decreased from 0.52 (control) to 0.46 at 4% alumina.