A “bricks-and-mortar” structured graphene oxide/polyvinyl alcohol coating: enhanced water interfacial lubrication and durability

Abstract

Coatings serve as ideal protective films for mechanical systems, providing dependable as well as efficient lubrication because of their unique structure along with outstanding tribological characteristics. Inspired by the “bricks-and-mortar” structure, we prepared layered graphene oxide (GO) composite finishes strengthened with polyvinyl alcohol (PVA) and borax. Our study demonstrates that the tribological properties of the GO-based coating on 304 stainless steel (SS304) are potentially greatly affected through PVA, GO, and annealing. By optimizing the composition, we achieved the PVA_{40 wt%}/GO_{0.01 wt%}/borax composite coating, which exhibited the lowest average coefficient of friction (COF) of 0.021±0.003 (a 97.86% reduction compared to control SS304) with minimal wear and abrasion even in a water environment. We found that the enhanced mechanical characteristics as well as elastic recovery within the coating were attributed to the hydrogen bonds and cross-linking between PVA and borax, which led to stress distribution. Reduced friction was further aided by the formation of a hydrated layer at the friction interface. As a result, the coating demonstrated remarkable durability, maintaining a low COF during long sliding distances (576 m, 28,800 cycles, significantly longer than previously reported) without breaking.