Britannica Sources used in this answer

Why can graphite be used as a lubricant?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

A color-coded periodic table of the elements displays each element's symbol and atomic number, with categories such as alkali metals, noble gases, halogens, transition metals, and actinoid elements distinguished by different background colors. — carbon group element Modern version of the periodic table of the elements (printable).

Graphite functions as an effective lubricant primarily due to its unique crystal structure, which consists of parallel layers of carbon atoms arranged in fused hexagonal rings. Within each layer, the carbon atoms are held together by strong covalent bonds, while the bonds between the layers are relatively weak van der Waals interactions.12

This structural arrangement allows the individual layers (or laminae) to slide easily over one another, providing the material with its characteristic softness and lubricity. Furthermore, graphite's low friction is significantly enhanced by the presence of adsorbed films, such as water vapour; in the absence of such films, graphite can lose its lubricating properties and become abrasive. Because of this layered, "layer-lattice" structure, graphite is classified as a solid lubricant, capable of maintaining stability under various conditions.12