Synergistic effect between h-BN and MoS₂ for excellent lubrication of solid lubricant coating for high-temperature, open-air-system applications

High-temperature solid lubricant coatings with decent lubrication performance are essential in critical processes of metal forming and aerospace. However, their preparation is formidably challenging due to the harsh working conditions. Here, we successfully developed a solid lubricant coating via a facile and eco-friendly approach by casting a homogeneous mixture of molybdenum disulfide (MoS₂) and hexagonal boron nitride (h-BN) as lubricants, silicate as the binder, and water as the solvent onto a titanium alloy substrate. This solid lubricant coating exhibited excellent and stable tribological properties with a very low coefficient of friction (COF) of 0.080 at 1,000 °C, yet in an open-air atmosphere. This superior lubrication behavior is attributed to the synergistic effect between the base lubricants h-BN and MoS₂, contributing to the formation of a coating for both lubrication and lubricant protection against oxidation at 1,000 °C in an open-air environment. This work largely extends the operation temperature range of the crucial lubricant MoS₂ in an open-air atmosphere and further sheds valuable light on the design of high-temperature solid lubricants via the synergistic effect between base lubricants.