Semi-solid lubricants are a gel-like substance which reduced friction between two moving surfaces.
E.g.; greases, Vaseline, waxes
semi-solid lubricants (Greases)
Greases are semi-solid lubricants obtained by thickening of lubricating oil by the addition of metallic soaps. Soaps are prepared by saponification of vegetable oils (or) fats with alkali (like as thickness (or) gelling agents).
“The lubricants that exist in solid form are called solid lubricants”. E.g.: – graphite,molybdenum disulphide etc. They are used in heavy machines under high load and low speed.