Thermal Characteristics and Tribological Performances of Solid Lubricants: A Mini Review

Abstract

Solid lubricants separate two moving surfaces and reduce wear. Materials’ ability to act as solid lubricants depends on their characteristics relative to contact surfaces. Chemically stable fluorides (BaF2, CaF2), boron nitride (h-BN), transition metallic sulphides (MoS2, WS2), soft metals (Au, Ag), binary and multi-component oxides, such as silver-containing sulphates, chromates, and oxides, and MXenes are effective solid lubricants. Solid lubrication depends on the material’s structure. Structure, mechanical properties, chemical reactivity, and kind of substance characterise these materials (refractories, ceramics, glass, etc.). High temperatures (>300°C) are obtained at asperities due to frictional heat produced when two surfaces rub. High temperatures can breakdown lubricants, but the resulting compounds must be lubricants; otherwise, corrosive vapours or abrasive solids can occur. High thermal conductivity helps lubricants remove heat generated by rubbing. Lubricants must not be melted, as the solid will lose strength and distort or be removed like liquid. Tensile strength, compressibility, and hardness are significant mechanical qualities for solid lubricants in extreme conditions. This chapter discusses solid lubricants and their structure. Also discussed are solid lubricants’ mechanical and thermal properties. The lubricating mechanism and conclusion are also conferred.