Effect of Particle Size and Content of <scp> Al ₂ O ₃ </scp> on Friction Behavior and Wear Mechanism of Epoxy Resin Composite

ABSTRACT Al 2 O 3 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 Al 2 O 3 ‐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 Al 2 O 3 . The study showed that, compared with 1 μm Al 2 O 3 , the tensile strength and fracture toughness of 30 and 80 nm Al 2 O 3 ‐EP increased significantly. This was because 1 μm Al 2 O 3 was prone to causing defects in the matrix and could not effectively inhibit crack propagation. However, micron‐Al 2 O 3 played a more significant role (~22.5%) in enhancing the Vickers hardness of the composites compared with nano‐Al 2 O 3 . This was because micron‐Al 2 O 3 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 Al 2 O 3 ‐resin composites based on 8 wt.%, the friction coefficient and wear rate of the 80 nm and 1 μm Al 2 O 3 ‐resin composites increased by 10.0% and 34.1%, as well as 55.2% and 90.0%. This indicated that an increase in Al 2 O 3 particle size weakened the tribological properties of the matrix. Meanwhile, the mechanism by which Al 2 O 3 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.