Robust lubricious and low corrosive imidazolium hexafluorophosphate lubricant on multi-arc ion plating Ag-Cu/Ti film under sliding electrical contact

摘要

In the presence of flooded imidazolium hexafluorophosphate (LP108), Ag-Cu/Ti film prepared by multi-arc ion plating is well lubricated but severely corroded due to electrochemical corrosion even by using benzotriazole as a corrosion inhibitor. Although imidazolium methyltributylammomiumbis ((trifluoromethyl)sulfonyl)imide ([HEMIM]NTf2) is much less corrosive to Ag-Cu/Ti film, its lubricity is inferior to that of LP108. Preapplied LP108 on top of Ag-Cu/Ti film by dipping and withdrawing from 0.2 vol% LP108-ethanol solutions exhibits comparable lubricity as flooded LP108, and comparable corrosion as flooded [HEMIM]NTf2. The localized liquid LP108 around spherical and top-flat droplets of Ag-Cu/Ti film gives birth to in-situ hybrid Ag-LP108 tribo-layer upon sliding contact. Meanwhile, tribochemical affinity between PF6 anion and tribo-surface is another reason for good lubricity.