Friction and Antiwear Characteristics of Ashless Friction Modifiers in the Presence of Sulfur and Phosphorus (S-P) Additives

摘要

Friction and antiwear characteristics were determined for oils an containing ashless friction modifier (FM) with and without sulfur and phosphorus (S-P) additives with a pin-on-disk type tribometer. FMs were glycerin monooleate (GMO), glycerin monooleylether (GME), tallow diethanolamine (TDEA), and hydroxyparmityldiethanol amine (HPDEA). Experiments were made using the step load method ranging from 200 to 440 N with the load increment of 40 N under the oil temperature of 100℃ and a sliding speed of 0.5 m/s. Magnitude of friction reduction effect depends on the type of ashless FM and the concentration of S-P additive. Among FMs, HPDEA showed the highest effect on friction reduction and antiwear performance, followed by TDEA, GMO, and GME. The contact potential for the oil containing only S-P appeared under a light load, whereas it continued to show zero level for a combination of HPDEA and S-P. XPS analysis showed the presence of FeS{sub}2 on the sliding surface lubricated with the oil containing HPDEA with S-P. This indicates that HPDEA, preferentially adsorbed onto the metal surface, played a role promoting formation of the boundary lubrication film containing FeS{sub}2 derived from an S-P additive.