Improvement of tribological and anti-corrosive performance of titanium surfaces coated with dicationic imidazolium-based ionic liquids

Abstract

In this work, dicationic imidazolium-based ionic liquids (ILs) with amino acid anionic moieties were employed as coatings for commercially pure titanium (Ti) surfaces. Coated and non-coated samples were tested with regard to their anti-corrosive and lubricant properties. Phosphate buffer saline (PBS), artificial saliva, and 50/50 PBS–saliva (v/v) were used as electrolytes during electrochemical testing and as control lubricants for Ti samples during tribological testing. Samples coated with ILs possessing longer alkyl chains in their spacer group and more hydrophobic anionic moieties, such as phenylalanine, demonstrated superior anti-corrosive and lubricant behavior. Protection against corrosion was reflected in lower corrosion current (I_corr) and corrosion rate values as well as independently measured higher polarization resistance values. Immersion medium was also observed to influence the corrosion behavior of samples. Control Ti exhibited increased susceptibility to corrosion in more acidic environments (artificial saliva) while the opposite trend was observed for IL-coated Ti samples. Enhanced lubrication was verified by a significant reduction in the coefficient of friction and total wear volume loss of IL-coated samples in comparison to control Ti.