Controllable in-situ synthesis of MoS2/C in plasma-sprayed YSZ coatings: Microstructure, mechanical and tribological properties

Abstract

Plasma-sprayed ceramic self-lubricating coatings are limited in their practical applications due to the degradation of mechanical properties caused by tribological design. Herein, a robust self-lubricating ceramic coating was fabricated by combining in-situ synthesis of molybdenum disulfide/carbon (MoS2/C) with the plasma spray technology process. Results show that MoS2/C grows in-situ in the pores and microcracks of plasma-sprayed yttria-stabilized zirconia (YSZ) coatings. Through the addition of MoS2/C, the hardness and cohesive strength of the coating could be significantly improved. Furthermore, the composite coating with the highest MoS2/C content exhibits the best tribological properties: the coefficient of friction is reduced by 79.6 % to 0.16, and the specific wear rate drops from 1.36 × 10−3 to 6.27 × 10−7 mm3 N−1·m−1. The improved tribological performance is attributed to a well-covered lubricating film composed of C, MoS2, YSZ, and Al2O3. The proposed strategy eliminates the most significant pain points of mechanical properties degradation of traditional ceramic self-lubricating coatings caused by tribological design and is believed to have great potential applications in wide engineering sectors.