Nanolubricant additives: A review

Abstract Using nanoadditives in lubricants is one of the most effective ways to control friction and wear, which is of great significance for energy conservation, emission reduction, and environmental protection. With the scientific and technological development, great advances have been made in nanolubricant additives in the scientific research and industrial applications. This review summarizes the categories of nanolubricant additives and illustrates the tribological properties of these additives. Based on the component elements of nanomaterials, nanolubricant additives can be divided into three types: nanometal-based, nanocarbon-based, and nanocomposite-based additives. The dispersion stabilities of additives in lubricants are also discussed in the review systematically. Various affecting factors and effective dispersion methods have been investigated in detail. Moreover, the review summarizes the lubrication mechanisms of nanolubricant additives including tribofilm formation, micro-bearing effect, self-repair performance, and synergistic effect. In addition, the challenges and prospects of nanolubricant additives are proposed, which guides the design and synthesis of novel additives with significant lubrication and antiwear properties in the future.