Transition Metal Dichalcogenide-Based (MoS₂, WS₂) Coatings

Transition metal dichalcogenides (TMD) are solid lubricant materials, specifically, intrinsic solid lubricants, whose crystal structure facilitates interfacial sliding/shear to achieve low friction and wear in sliding contacts and low torque in rolling contacts. This article provides information on sliding friction and wear behavior of unbonded, bonded, and vapor-deposited pure and composite MoS₂ and WS₂ coatings. It discusses the rolling-torque behavior and applications of vapor-deposited pure and composite MoS₂ and WS₂ coatings. The article concludes with information on various forms of TMD lubrication, namely, oils, greases, microparticle and nanoparticle additives.