Tribocatalytically-activated carbon-based tribofilm formation for wear reduction in alkane environment

Abstract

Minimizing the wear of the surfaces exposed to mechanical shear stresses is an ideal solution to maximizing the lifespan of rotary mechanical parts. In this study, we have discovered the anti-wear capability of a series of metal nitride-copper nanocomposite coatings tested in a liquid hydrocarbon environment. The results indicate substantial reduction of the wear in comparison to the uncoated steel substrate. Analysis of the wear tracks indicates the formation of carbon-based protective films directly at the sliding interface during the tribological tests. Raman spectroscopy mapping of the wear track suggests the amorphous carbon (a-C) nature of the formed film. Further analysis of the tribocatalytic activity activation as a function of load (0.25-1 N) and temperature (25°C, and 50°C) was performed in three alkane solutions, decane, dodecane, and hexadecane. Results indicated that elevated temperature and high contact pressure result in more stable friction behavior of the coating. The elemental energy dispersive x-ray spectroscopy analysis and Raman analyses reveal how a-C film facilities easy shearing at the contact interface thus enabling more stable friction and lower wear at higher loads and elevated temperature. These results provide new insights into the tribocatalysis mechanism that enables the formation of zero-wear coatings.

Tribocatalytically-Active Coatings for Enhanced Tribological Performance and Carbon-Based Tribofilm Formation

“…Additionally, in the evaluation of MoN-Cu and VN-Cu coatings with catalytic properties, dodecane demonstrates the lowest propensity for tribofilm formation among the tested alkanes, while decane and hexadecane display more uniform tribofilm structures [32].…”

“…The study and understanding of the formation and properties of carbon-based tribofilms from hydrogenated alkanes [16] and hydrocarbon-rich environments [15,32] during tribological tests are essential for improving lubrication efficiency, reducing wear, and enhancing the performance and durability of sliding surfaces in various applications. Recent investigations have revealed that longer-chain hydrocarbons, specifically hexadecane, exhibit enhanced tribocatalytic activity and higher reactivity compared to their shorter-chain counterparts.…”

“…In [32], the authors mentioned that even though breaking C-C bonds is easier than dehydrogenation (C-C: ~347 kJ mol-1; C-H: ~414 kJ mol-1), Cu is one of the catalysts that is able to facilitate breaking H-C bond releasing H from lubricants. Moreover, [54] explored the influence of varying amounts of Cu in Cu/Al2O3 catalysts on the conversion of glycerol.…”