Strengthening mechanism of different morphologies of nano-sized MSH on tribological performance of phosphate/MoS2 bonded solid lubricating coatings

Abstract Magnesium silicate hydroxides (MSHs) with granular, schistose, and tubular morphologies were separately incorporated to enhance the tribological properties of phosphate/MoS 2 composite coatings. The nano-schistose MSH demonstrated superior tribological performance due to its effective interactions with the worn surface and frictional synergies with solid lubricants. Incorporation of nano-schistose MSH decreased the friction coefficient of composite coatings by about 34.7% and increased the anti-wear performance of composite coatings by about thirteen times. Nano-schistose MSH facilitated the formation of a friction-induced multi-layer heterogenous slipping structure with layered solid lubricants at the friction interface. Moreover, tribo-chemical reactions between nano-schistose MSH and worn surface promoted the in-situ formation of a cermet supporting film, and this also induced the gradual in-situ formation of a lubrication film on the top of worn surface. Consequently, the contact state between tribo-pairs was timely regulated and the invalidation of the nanocomposite slipping structure was effectively restrained during the friction process. As a result, the service life of the phosphate composite coatings was significantly extended and further abrasion on the worn surface was notably reduced.