Investigation of Lubricious and wear-protective Carbon tribofilm from a metastable organic lubricant additive

Arman Khan,¹ Hongxing Wu,^1,2 Yip-Wah Chung,^1,3 and Q. Jane Wang,¹

¹Department of Mechanical Engineering, Northwestern University, Evanston, IL 60208, USA

²Key Laboratory of Education Ministry for Modern Design and Rotor Bearing Systems, Xi’an Jiaotong University, Xi’an 710049, P. R. China

³Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA

The presence of a thin protective layer between rubbing surfaces is important for ensuring minimum energy dissipation and prolonging the operating life of mechanical systems. The authors have developed a method to produce a carbon tribofilm in-situ that can result in low friction and provide an on-demand wear protection without any pre-treatment of the contact surfaces. Friction and wear performance of base oil with this additive under a range of loads and speeds yielded superior results to that without the additive. Systematic experimental characterizations and reactive molecular dynamics simulations were conducted to explore the nature of the carbon tribofilm, analyze the related tribochemistry and reveal the atomistic mechanisms involved that leads to formation of such tribofilm. Our findings pose an important result towards a better understanding of tribofilms and benefits to future tribo-material, lubricant and friction interface design.