Abstract

Efficient lubrication under harsh conditions is essential for aerospace, automotive, and electrical systems. Novel two-dimensional (2D) materials can serve for this purpose by providing materials with low friction and excellent wear-resistance under these conditions. Therefore, we studied the solid lubrication performance of a novel boridene phase (MoAlB etched into layered 2D Mo2B2 MBene) spray-coated onto stainless-steel substrates. Studies on elemental and phase composition demonstrated the preferential etching of Al over Mo from the parental phase, while infrared spectroscopy confirmed -OH and B-O groups. The MBene demonstrated adequate colloidal stability, which is essential for the generation of homogeneous solid lubricant coatings. The solid lubrication performance of MBene was tested using ball-on-disk tribometry, revealing a promising reduction in friction and wear by 50%, even under a load of 400 mN (contact pressure of 0.8 GPa). Raman spectroscopy confirmed the formation of a beneficial tribo-layer, comprising both the initial MBene and its oxidation products, which played a cruical role in reducing observed friction and wear. Furthermore, calculated mechanical parameters demonstrated its elastic stability, meeting Born-Huang criteria. Mo2B2's elastic constants fall between other 2D materials such as MXenes, graphene, and MoS2, with surface functionalization impacting its mechanical properties. Altogether, our study provides cutting-edge knowledge about the promising solid lubrication performance of MBenes.