Effect of the structure and metal atom of dialkyldithiophosphate derivatives on the wear behaviour in steel‐zirconia contacts

Abstract

Wear investigations concerning the different structures and metal atoms of metal dialkyldithiophosphates (MeDTPs) were conducted using a ball‐on‐disc apparatus. Steel ball bearings (3.175 mm in diameter) and counterface discs, made of hot pressed ZrO2 partially stabilised by Y2O3, were used. The synthesised MeDTPs were made up of primary linear aliphatic alcohols with hydrocarbon lengths varying from 8 to 16 carbon atoms, and contained the following metals: zinc(II), iron(III), gallium(III), antimony(III), and copper(II). Tests were performed at room temperature. The sliding speed was set to a constant 0.03 m/s, and a constant 30 N load was used. The additives investigated were used as solutions in n‐hexadecane. The study also focused on the influence of additive concentration on wear. It was found that the effectiveness in reducing wear depends both on the metal atom and on the length of the hydrocarbon chain in the additive's molecules. The lowest wear volumes were observed for additives with n‐octyl and n‐tetradecyl hydrocarbon chains. The worst antiwear performance was observed for n‐dodecyl derivatives. For almost all additives, more concentrated solutions resulted in less wear. Some friction coefficient results are also presented.

Synthesis, Physicochemical, and Tribological Characterization of S-Di-n-octoxyboron-O,O′-di-n-octyldithiophosphate

“…In a recent review on the history and action mechanism of ZnDTPs with metal surfaces (10), it is concluded that it has been so far proven impossible to identify any reasonably cost-effective compound having comparable antiwear properties to ZnDTPs lubricant additives. A survey of literature reveals that dialkyldithiophosphate esters (11), dialkyldithiophosphates of different metals such as molybdenum (12), cadmium (13), copper (14), titanium (15), gadolinium (16), iron, antimony, and other metals (17)(18)(19) have been introduced and used as multifunctional additives in lubricants. To the best of our knowledge, there are no open publications on boron dialkyldithiophosphates as additives in lubricants.…”