Construction and corrosion resistance mechanism of BTA passivation film on B30 cupronickel

Material corrosion is a critical factor leading to structural failure, performance degradation, and significant economic losses, particularly in harsh marine environments. Therefore, enhancing the corrosion resistance of metallic materials is crucial for extending equipment service life, ensuring operational safety, and reducing maintenance costs. This work elucidates the passivation mechanism of 1,2,3-benzotriazole (BTA) on B30 cupronickel (Cu 30Ni alloy, UNS C71500) through integrated electrochemical analysis and 28-day artificial seawater immersion testing. XPS characterization revealed a multi-component passivation layer (20–30 nm thickness) comprising Cu(I)-BTA organometallic compounds, Ni(II)-BTA chelates, and crystalline Cu₂O domains. The optimized BTA treatment enhanced surface hydrophobicity, evidenced by a 20 % increase in water contact angle (85° → 102°). Electrochemical polarization demonstrated remarkable corrosion current density suppression from 18.5 μA/cm 2 (bare alloy) to 0.504 μA/cm 2 (passivated), indicating two-order-of-magnitude improvement. Long-term immersion tests at 25 °C showed 87 % reduction in corrosion rate (0.0114 → 0.0015 mm/a). The synergistic effects of organic-inorganic hybrid film formation and hydrophobicity enhancement establish BTA passivation as a viable eco-friendly alternative to chromate treatments for marine alloy protection.