Low humidity-sensitivity of MoS2/Pb nanocomposite coatings

• The MoS2/Pb composite coatings with dense morphology were prepared.
• Suitable doping of Pb improved the mechanic properties of the coatings.
• Under dry air, the tribo-performance of the coatings was determined by H/E value.
• Under humid air, the tribo-performance was controlled by antioxidant property.
• The coating of suitable doping of Pb showed high environmental adaptability.

Optimizing the MoS2-based coating to overcome its humidity sensitivity is still a challenge. In this work, MoS2/Pb composite coatings with various Pb contents were synthesized by unbalanced magnetron sputtering system. The microstructures of the coatings change from loose columnar structure for pure MoS2 to a compact featureless structure for Pb doped MoS2. The hardness and elastic modulus of the MoS2/Pb composite coatings gradually increase with the Pb content increase and exhibit a maximum value at Pb content of 8.9 at%. Further increase in the Pb content results in a decrease in the hardness and elastic modulus of the coatings. The tribological performance of the coatings was systematically evaluated under different humidity conditions, and the underlying mechanisms were investigated. The results show that the mechanical property of the coating determines the wear properties under dry air; whereas the antioxidant property of the coating becomes prominent with regard to the wear-resistant in humid environmental. This benefits us to tailor or select the MoS2-based composite coatings for different operating conditions.