Effect of Particle Size and Content of Al₂O₃ on Friction Behavior and Wear Mechanism of Epoxy Resin Composite

Al₂O₃ particles with different sizes (30 nm, 80 nm and 1 μm) and content (6, 8, and 10 wt.%) were applied to improve the mechanical and tribological properties of Al₂O₃-epoxy resin composites. The mechanical properties, surface hardness, friction behaviors, and wear mechanisms of the composites were analyzed to determine the reinforcing and toughening effects of Al₂O₃. The study showed that, compared with 1 μm Al₂O₃, the tensile strength and fracture toughness of 30 and 80 nm Al₂O₃-EP increased significantly. This was because 1 μm Al₂O₃ was prone to causing defects in the matrix and could not effectively inhibit crack propagation. However, micron-Al₂O₃ played a more significant role (~22.5%) in enhancing the Vickers hardness of the composites compared with nano-Al₂O₃. This was because micron-Al₂O₃ occupied a larger volume in the three-dimensional network structure of the resin, providing greater spatial obstruction, which made the indentation of the microprobe shallower when subjected to the same hardness. Additionally, compared to the 30 nm Al₂O₃-resin composites based on 8 wt.%, the friction coefficient and wear rate of the 80 nm and 1 μm Al₂O₃-resin composites increased by 10.0% and 34.1%, as well as 55.2% and 90.0%. This indicated that an increase in Al₂O₃ particle size weakened the tribological properties of the matrix. Meanwhile, the mechanism by which Al₂O₃ enhanced the anti-wear of the resin can be attributed to the formation of a uniform and dense lubricating isolation film, which changed the wear type of the friction pair from fatigue wear to adhesive wear.