Synergistic Strengthening Mechanism of Hybrid Nanoreinforcement and Surface Pre-Treatment in Adhesive Joining with Alumina/SiC Nanoparticles

This study investigates the combined effects of Alumina/SiC hybrid nanoreinforcements and surface pre-treatment on the mechanical strength of adhesive joints. A two-component epoxy adhesive was reinforced with 1.0 wt% Alumina/SiC nanoparticles at ratios of 10:0, 7:3, 5:5, 3:7, and 0:10 to bond aluminum alloy substrates. The adherends were pre-treated with P320 and P3000 sandpapers to generate distinct surface roughness profiles. Joint performance was strongly influenced by the interaction between nanoparticle ratio and surface roughness, reflecting the complex mechanisms governing bonding strength. To quantify these effects, Pearson correlation and heatmap analyses were employed, enabling assessment of the relationships between experimental variables and joint properties. The optimal configuration was identified as a 5:5 Alumina/SiC ratio with a surface roughness of Ra = 0.18 ± 0.01 µm, which achieved the highest bonding strength, showing a 47.0% improvement over pristine adhesive. At the same roughness, this hybrid also outperformed single-nanofiller systems, with shear strength gains of 25.7% over Alumina (10:0) and 11.8% over SiC (0:10). Pearson analyses effectively captured these trends, providing a comprehensive evaluation of variable interdependencies and quantitatively highlighting the influence of nanoparticle composition and surface pre-treatment on adhesive joint performance.