Large control of friction and wear enabled by Ti3AlC2 MAX- multilayer graphene-polydopamine composites

Friction and wear pose significant challenges in moving mechanical systems. Despite efforts to address these challenges with MAX phase materials, many of these materials lack effective lubrication and wear protection under ambient conditions. Here, we developed a composite coating that addresses these challenges through a combination of materials chemistry and engineering. This coating, composed of polydopamine-functionalized Ti₃AlC₂ MAX (F-MAX) and multilayer graphene (MGr), known as F-MAX + MGr, demonstrated exceptional tribological performance. At its best composition, the F-MAX + MGr composite coating reduced the friction at sliding interfaces by 82 % and decreased the wear on the counterpart ball by 99.76 % compared to bare surfaces. Importantly, its tribological performance surpassed that of pristine MAX, F-MAX, and MGr coatings. This improvement is attributed to the synergistic lubricating effect of the inherently low shear strengths of Ti₃AlC₂ MAX and MGr, the chemical properties of PDA, and the occurrence of incommensurate contacts at the interfaces. This work pioneers slippery and wear-resistant surfaces via a combination of chemical modification and materials engineering, with implications for both fundamental science and technological advancement.