Effects of Hydrogen on Frictional Properties of DLC Films

Abstract

The tribological behavior of diamond-like carbon films (DLC) is strongly dependent on the hydrogen content, sp 2 /sp 3 ratio, and sliding environment. Some hydrogenated amorphous carbon films (a-C:H) exhibit superlow friction in hydrogen conditions. However, previous works have not clarified the dominant factors of the superlow friction phenomena of DLC films. In this research, we focused on the effects of hydrogen derived from the surrounding atmosphere and the hydrogen within the DLC films on superlow friction phenomena. To investigate these effects, friction tests were conducted on three DLC films having different hydrogen contents (0, and 18, 30 at%) in the air and in low-pressure-hydrogen conditions at various hydrogen pressures. After the friction tests, the wear tracks were examined by confocal laser scanning microscopy, Raman spectroscopy, elastic recoil detection (ERDA) analysis, and time-of-flight secondary ion mass spectrometry (TOF-SIMS). The hydrogen derived from the surrounding atmosphere and the formation of the hydrogen-rich tribofilm were key factors for the superlow friction phenomena.

Effects of Environmental Gas and Trace Water on the Friction of DLC Sliding with Metals

“…DLC is a strong candidate material for tribological components in these systems because of its favorable friction and wear performance with hydrogen. With this background, some studies focused on the behavior of DLC in hydrogen gas [ 41 , 42 , 43 , 44 , 45 ].…”

Effects of Molecular Structure of Zinc Dialkyldithiophosphates on Tribological Properties of a Hydrogenated Amorphous Carbon Film under Boundary Lubrication

“…Due to their attractive properties, ZDDPs have been investigated by many research groups for the last several decades [4][5][6][7][8][9][10]. Therefore, it is well-known that ZDDP tribofilms on iron-based materials consist of gradient, patchy, and pad-like structures, which are composed of phosphate glasses, zinc phosphates, and sulfur-rich layers [1][2][3][4][5]. The occurrence of these tribofilms on this kind of material contributes to their use in improving the tribological performance of iron-base surfaces.…”

Proposal of Biomimetic Tribological System to Control Friction Behavior under Boundary Lubrication by Applying 3D Metal Printing Process

“…To control friction and wear, many research studies have been conducted on surface-modification techniques such as surface texturing [1][2][3][4][5][6][7][8] and surface coating [3,[8][9][10]. Surface texturing is especially effective in controlling tribological properties under different lubrication regimes (boundary, mixed [1][2][3], and hydrodynamic lubrication [4,5]) because it plays multiple roles in controlling friction and wear, such as trapping abrasive particles [2,3], supplying lubricants to sliding surface [2,3], and creating a loadcarrying capacity [5].…”