Carbon nanomaterials as friction modifiers in automotive engines: Recent progress and perspectives

Recent efforts are widely focused on developing and usage of carbon nanomaterials in tribological research, including nanolubricants, fabrication of self-lubricating materials and preparing coatings to improve anti-friction/wear properties of the worn surfaces in automobiles. The main goal of this study is to have an overview of the role of carbon nanomaterials and their derivatives in improving the tribological behavior and thermophysical properties of the engine oils. Herein, we elucidated the main nanolubricant mechanisms responsible for improving anti-friction/wear properties. Furthermore, this article reviews the main problems and some suggestions for future directions of research. In summary, the review provided the main achievements of the carbon nanolubricants to guide future lubricant oils development. [Display omitted] •Preparation routes and characterization of carbon nanolubricants are discussed.•This review provides major mechanisms and empirical correlations of nanolubricants.•Tribological performance of carbon nanolubricants is elucidated.•Thermophysical properties of carbon nanolubricants are summarized.•The challenging issues and research gaps that remain unresolved are discussed.