INFLUENCE OF CR-FREE ANTI-FINGERPRINT PASSIVATION FILMS ON THE FRICTION RESISTANCE OF HOT-DIP Al-Zn COATED CARBON STEEL SHEETS

Currently, the absence of an effective scientific methodology for evaluating the friction resistance of Cr-free anti-fingerprint Al-Zn coated carbon steel sheets has significantly hindered the qualitative assessment and real-time monitoring of product quality by manufacturers and their downstream users. In this study, we systematically investigate the friction resistance of Al-Zn coated carbon steel sheets treated with three mainstream types of Cr-free anti-fingerprint passivation solutions: polymer-based (Granocoat 621), silane-based (DS981LX), and resin-based (PC-815) passivation solutions, utilizing a high-speed ring-block friction and wear tester. Our experimental results reveal that the friction coefficient curves exhibit a distinct three-stage pattern, corresponding to the sequential wear of the passivation film, the Al-Zn alloy layer, and the underlying carbon steel substrate. Notably, the initial significant increase in the friction coefficient is indicative of a failure of the passivation film due to wear. The friction durability of the Granocoat 621, DS981LX, and PC-815 passivation films was determined to be 287 s, 581 s and 684 s, respectively, with the water-based polyurethane resin-based passivation film (PC-815) demonstrating superior friction resistance. This enhanced performance is attributed to the strong chemical bonding between the water-based polyurethane and the Al-Zn alloy layer, as well as the synergistic effect of the silane coupling agent. These findings provide both theoretical and experimental foundations for establishing a scientifically validated method for evaluating the friction resistance of Cr-free anti-fingerprint Al-Zn coated carbon steel sheets, offering crucial insights for manufacturers aiming to improve the friction resistance of their products.