Abstract
A series of new halogen-free dicationic ionic liquids (ILs) with different alkyl chain lengths were prepared, and the relationship between the alkyl chain length, physicochemical and tribological properties of ILs, and their role as neat lubricant for steel-steel friction pairs, was investigated. Evaluation of stability during hydrolysis and copper strip corrosion test results show that synthetic ILs are stable and not corrosive to metal contacts, due to the halogen-free anions. The friction and wear test results indicate that ILs with long alkyl chains have excellent friction-reducing and anti-wear properties, especially at high temperatures. Based on the surface three-dimensional (3D) profiles, electrical contact resistance, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and the X-ray photoelectron spectrometry (XPS) analysis of the worn surfaces of steel discs, we can conclude that the efficiency of ILs is due to the formation of high quality tribofilms that consist of both tribochemical reaction and ordered absorption films.
Highlights
Friction and wear result in energy wastage and shorten the service life of mechanical components [1]
ionic liquids (ILs) have been explored as lubricants for various frictional materials, due to their excellent dipolar structure and physical properties like extremely low volatility, nonflammability, high thermal stability, low melting point, and good thermal conductivity; the latter allowing for rapid frictional heat dissipation [9,10,11,12,13,14]
This law is consistent with the experimental results of wear volume (Fig. 5(b)), suggesting that the alkyl chain length of ILs has an important effect on the stability of the boundary lubricant film, considering the lubrication interval
Summary
Friction and wear result in energy wastage and shorten the service life of mechanical components [1]. A large number of studies in the tribological field are mainly focused on halogen-containing mono-cation ILs based on anions Friction such as [BF4]–, [PF6]–, [CF3SO3]–, and [NTf2]– [15,16,17]. Mahrova et al [21] synthesized a series of bi-cationic pyridine-type ILs, and systematically studied their tribological properties as lubricant and additive This series of ILs uses [NTf2]– as an anion and exhibits excellent friction-reduction and anti-wear properties. Gusain et al [29] synthesized and evaluated a series of bis(imidazolium)- and bis(ammonium)-di[bis(salicylato)borate] ILs with variable alkyl chain and cyclic ring structures as potential lubricant additives These dicationic ILs as additives of PEG200 showed noncorrosive properties, which were attributed to the of corrosion driven elements, such as halogens, in these ILs. In this study, we designed a new type of halogenfree dicationic IL, based on the gemini-type molecular structure. The constructed ILs are excellent lubricants and have excellent thermal stability
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
