Understanding the friction dependence of textured amorphous carbon film on sliding angle under oil lubrication condition

Abstract

The combined design of lubricating oil and textured surfaces can optimize the friction performance of amorphous carbon (a-C) films. However, due to the limitations of experimental characterization methods, the impact of sliding direction on the friction behavior of textured a-C films remains unclear, particularly regarding the mechanisms of interface structural transformation and lubricating oil flow behavior. Therefore, this study constructed rectangular textured a-C films and investigated the effect of sliding angle on the tribological properties of a-C under oil lubrication condition by reactive molecular dynamics simulations. Results indicate that the friction properties of a-C films are significantly influenced by the sliding angle. As the sliding angle increases from 0 degrees to 60 degrees, the friction interface dominated by the passivation process, exhibits an increase in saturated bond content, leading to a reduction of the friction coefficient at 30 degrees and 60 degrees. However, when the sliding angle reaches 90 degrees, the lubricating oil is primarily concentrated between the textured protrusions and the upper friction pair, leading to a failure in the oil storage function of the textured layer and an increase in the friction coefficient. These findings reveal the friction mechanisms of a-C films induced by sliding angle, effectively guiding the design and technical application of textured a-C films.