Study on the preparation and fretting behavior of bonded oriented MoS₂ solid lubricant coating

The bonded MoS₂ solid lubricant coating is an effective measure to mitigate the fretting wear of AISI 1045 steel. In this work, the amino functionalized MoS₂ was protonated with acetic acid to make the MoS₂ positively charged. The directional arrangement of protonated MoS₂ in the coating was achieved by electrophoretic deposition under the electric field force. The bonded directionally aligned MoS₂ solid lubricant coating showed high adaptability to various loads and excellent lubrication performance under all three working conditions. At a load of 10 N, the friction coefficient and wear volume of the coating with 5 wt% protonated MoS₂ decreased by 20.0% and 37.2% compared to the pure epoxy coating, respectively, and by 0.07% and 16.8% than the randomly arranged MoS₂ sample, respectively. The remarkable lubricating properties of MoS₂ with directional alignment were attributed to its effective load-bearing and mechanical support, barrier effect on longitudinal extension of cracks, and the formation of a continuous and uniform transfer film.