Fluorinated Boron Nitride Nanosheets-Based Solid Lubricating Coating for Tribological Applications at Elevated Temperatures

This study investigated the potential of a fluorinated boron nitride nanosheets (F-BNNSs)-based coating as a hot-forming lubricant for titanium alloys. The F-BNNSs were prepared through wet ball milling with hexagonal boron nitride (h-BN) powder and ammonium fluoride (NH4F), and the coatings were deposited by the spray method. The tribological behavior of coatings on pure titanium (TA1)/silicon nitride (Si3N4) frictional pairs was examined at 800 °C. The results demonstrated that F-BNNSs coatings exhibited excellent thermal stability, with the F-BNNSs3 coating (the mass ratio of h-BN to NH4F of 1:3) exhibiting the best tribological performance. The average coefficient of friction (COF) and wear rate reduced by 15 and 79% compared with the hexagonal boron nitride nanosheets (h-BNNSs) coatings, respectively. The excellent tribological properties of F-BNNSs coatings were attributed to the lower interlayer shear force, nanostructure, and interfacial behavior, which contribute to the formation of self-lubricating and friction-induced reaction films. Therefore, the F-BNNSs coating has shown potential application in the field of titanium alloy hot-forming.