MBT-functionalized carbon dots for enhanced water-based lubrication: Superior friction reduction and corrosion inhibition

As environmental concerns grow, water has emerged as a recyclable and renewable eco-friendly lubricant with distinct advantages. However, the severe corrosion of friction pairs induced by water-based lubrication hinders its broader application. This study presents a strategy for preparing mercaptobenzothiazole-functionalized carbon dots (N,S-CDs(MBT)) by a one-step hydroxyl-alkylation as water-based lubricant additives. At a concentration of 1.0 wt%, these additives reduce the coefficient of friction by 80.6 % (from 0.474 to 0.092) and the wear volume from 29.81 × 10⁵ μm³ to 7.65 × 10⁵ μm³. This performance is attributed to the synergistic effect of tribological protective films, amorphous carbon films, and stable hydration layers formed on the friction pairs. Furthermore, N,S-CDs(MBT) efficiently suppress surface corrosion, reducing corrosion current density (i_corr) by two orders of magnitude when added at 500 mg/L, achieving a corrosion inhibition efficiency up to 98.7 %. This approach effectively mitigates corrosion issues in water-based lubrication, promoting environmental sustainability and industrial application.