Influence of ethyl acetate and alkyl phosphate adsorption on the frictional properties of VC(100)

Abstract

This report presents ultrahigh vacuum measurements of the frictional properties of the non-polar (100) surface of vanadium carbide (VC) as a function of the room temperature uptake and reaction of ethyl acetate, triethyl phosphate, and trimethyl phosphate. Atomic force microscopy, employing a silicon nitride probe tip, has been used to determine the changes in friction and interfacial adhesion as a function of adsorbate uptake. Changes in surface morphology have been monitored with scanning tunneling microscopy while the composition of the surface species formed through the reaction of these adsorbates with the VC surface has been determined by X-ray photoelectron spectroscopy. Adsorption and reaction of ethyl acetate leads to an increase in friction with little change in interfacial adhesion. The adsorption and reaction of triethyl phosphate and trimethyl phosphate have no influence on either the friction or adhesion properties of VC. The observed results are discussed in terms of the surface chemical composition, the extent of surface coverage, and the molecular details of the adsorbed species.

Compositional dependence of the microscopic frictional properties of single crystal metal carbides

“…Previous studies of VC(100) under ultrahigh vacuum conditions have demonstrated that surface composition strongly influences frictional properties [6][7][8][9]15]. Our present study demonstrates that similar effects exist for carbide surfaces at higher pressures, in the presence of partial surface oxidation, and as a function of metal constituent of the carbide.…”

“…The frictional properties of TiC(100) and VC(100) under ambient and ultrahigh vacuum (UHV) conditions have been the subject of recent studies from our group [6][7][8][9]. These investigations demonstrated that TiC exhibits inherently lower friction than VC under ambient conditions and that this effect does not arise from differences in surface oxidation; furthermore, the measured friction of each sample increased with increasing relative humidity [6].…”

“…The modification of VC through the room temperature adsorption of ethanol under vacuum conditions produces an $40% reduction in friction upon formation of a complete monolayer of the dehydrogenated species [7]. In contrast, adsorption of 2,2,2-trifluoroethanol [8] and ethyl acetate [9] on the VC(100) surface at room temperature leads to an increase in friction. Adsorption of triethyl phosphate and trimethyl phosphate has no influence on the friction properties of VC [9].…”

“…In contrast, adsorption of 2,2,2-trifluoroethanol [8] and ethyl acetate [9] on the VC(100) surface at room temperature leads to an increase in friction. Adsorption of triethyl phosphate and trimethyl phosphate has no influence on the friction properties of VC [9].…”

Tribological Characteristics of Alkylimidazolium Diethyl Phosphates Ionic Liquids as Lubricants for Steel–Steel Contact

“…As one of the most used additives of lubricating oil [16][17][18][19][20][21][22][23][24], phosphate can be used to make an ionic liquid possessing both excellent lubrication/anti-wear characteristics and no corrosion issue to metallic friction pairs if phosphate could be modified by being coordinated with some cations that cannot be easily hydrolyzed. Inspired by this idea, a series of ionic liquids consisting of phosphate anions and alkylimidazolium cation were synthesized, and the tribological properties of these ionic liquids as lubricants were studied as well.…”