Nanostructure of Superlubricating Tribofilm Based on Friction-Induced a-C:H Films under Various Working Conditions: A Review of Solid Lubrication

Abstract

Diamond-like carbon (DLC) film has gained widespread popularity as a versatile and important solid lubricant material in the field of tribology. Among various types of DLC films, hydrogen-rich DLC (a-C:H) film as a high-performance material has greatly enhanced anti-friction and anti-wear. However, despite its remarkable capabilities, the surface chemical properties and tribological performance of a-C:H film are significantly influenced by the surrounding environment, in special atmospheric conditions. Its super-slip mechanism involves the participation of hydrogen atoms, which can weaken the normal electron number of the outermost layer of a-C:H film. What is more, it is essential to investigate tribofilms in a vacuum or inert gas environment to ascertain the appropriate tribological properties of a-C:H film, which helps in mitigating oxidation effects. When non-doped DLC films are subjected to friction in a dry nitrogen or argon environment, they create sp3-C-rich transfer films on the contact surface, resulting in macroscopic super-slip effects. This paper aims to introduce and discuss the diverse nanostructures of in situ tribofilms in a-C:H film, focusing on the working environment, and explore the prospective application directions of a-C:H film.

The Induced Orientation of Hydroxypropyl Methylcellulose Coating for Ultralow Wear

“…Here, S means the cross−section of the wear track derived from 3D white−light interference topography for a square millimeter unit; L means the stroke distance derived from the ball−on−disc tribometer for a millimeter unit; F means load set from the ball−on−disc tribometer for Newton unit; C means the whole stroke distance derived from the ball−on−disc tribometer for a meter unit. The unit of wear rate is mm 3…”

“…Friction and wear, which can cause serious damage to component surfaces, considerable energy consumption, and significant economic losses, have been regarded as the most urgent problems to be solved in modern industry. According to statistics, friction and, thus, induced wear constitute a large proportion of global energy consumption and component failures, which has become the main bottleneck restricting the reliability of current equipment and the development of a high−end manufacturing industry [1][2][3]. With the gradual improvement of environmental awareness worldwide and the continuous strengthening of government policies on environmental protection, the development of green solid lubricants has received widespread attention.…”