Influence of the structure of a hydrocarbon radical on the antifriction properties of phosphorothionates in biodegradable lubricants

Abstract

The study aim is to develop methods of efficiency enhancement for the antiwear additives in the lubricants based on hydrocarbon oils. The tribological properties of triaryl and trialkyl phosphorothionates with similar hydrocarbyl groups have been compared. The testing has been carried out in the contact unit of combined rolling and sliding friction. It has been shown that trioctyl phosphorothionate is considerably superior to tribenzyl phosphorothionate and triphenyl phosphorothionate in antifriction and antiwear properties. The obtained results validate the suggestion that for a given polar group contained in an antiwear additive molecule the maximal efficiency can be achieved with sufficiently great hydrocarbonyl groups, when their structures are similar to the prevailing structure of the lubricant hydrocarbon molecules.

On the Difference in the Action of Anti-Wear Additives in Hydrocarbon Oils and Vegetable Triglycerides

“…Several prior studies by the authors [28][29][30][31] support the concept of the adsorption mechanism of anti-wear additives in hydrocarbon oils. The models developed are based on the physico-chemical principles of secondary polymolecular adsorption of hydrocarbon liquid on metal surfaces that have been modified by surfactants, specifically AW additives.…”

“…At a load of 392 N, this concentration displayed the maximum effect, resulting in a 1.5-fold reduction in the wear spot diameter from 0.75 mm to 0.5 mm. However, our experimental studies of the contact tests that simulated a plain bearing revealed no discernible difference between the original and additive oils (Figure 3) [29].…”

“…At a load of 392 N concentration displayed the maximum effect, resulting in a 1.5-fold reduction in the spot diameter from 0.75 mm to 0.5 mm. However, our experimental studies of the c tests that simulated a plain bearing revealed no discernible difference between the or and additive oils (Figure 3) [29]. Thus, a proper evaluation of the effectiveness of the chosen or developed AW/E ditive requires the use of a test method that replicates the primary friction attributes desired technical assemblies.…”

“…They depend on both the base oil and additives. The influence of the additive structure is described in [29]. The model provides only a qualitative assessment; specific parameters are obtained empirically.…”