Tribological performance of organic molybdenum in the presence of organic friction modifier

Abstract

The tribological performance of organic molybdenum in the present of organic friction modifier was investigated in this study. Three types of organic friction modifiers were selected, which are Glycerol monooleate, Pentaerythritol and N,N-Dimethylhexadecylamine. The organic molybdenum are MoDTC, MoDDP and molybdenum amide. Friction coefficient and wear were studied in block-on-ring test rig with steel test specimens. Experimental results indicate the Pentaerythritol shows synergistic effect with MoDTC in wide range temperature, while increased the friction coefficient of molybdenum amide in high temperature. N,N-Dimethylhexadecylamine shows synergistic effect with molybdenum amide, while hindered the friction reduction performance of MoDTC in low temperature. The presence of Glycerol monooleate reduced friction coefficient of MoDTC in low temperature, while increased the friction coefficient of molybdenum amide in most situations. All the tested organic friction modifiers improved the friction reduction performance of MoDDP. Most of the tested organic friction modifiers reduced the wear of organic molybdenum. The PT shows the best anti-wear performance with MoDTC. The tribo-chemical products in test specimens lubricated with different lubricant formulas indicate that the presences of Pentaerythritol promotes the production of MoS2 in MoDTC. N,N-Dimethylhexadecylamine promotes the production of MoS2 in molybdenum amide. The side products of MoO1.6S1.6 and Cr/MoS2 of MoDDP in high temperature lead to high friction coefficient.

Towards outstanding lubricity performance of proton-type ionic liquids or synergistic effects with friction modifiers used as oil additives at the steel/steel interface

“…[11][12][13][14][15] The most extensively studied compound is dialkyl dithiophosphate oxygen molybdenum (MoDDP) which can control wear, scuffing and friction. 16,17 To date, research studies have shown that the tribo-chemical decomposition of organic molybdenum and the decomposition product of MoS 2 are the critical factors to decrease the friction coefficient that can slide easily between the layers during the friction process. 16 It is generally accepted that the functionality of organo-molybdenum may be highly influenced by the presence of other functional additives in lubricants because the use of more than one modifier additive together may interact synergistically or antagonistically, 18 while the multiple additives in the system such as anti-wear (AW) additives, friction modifiers (FMs) and their interactions in the lubricant are critical to tribological performance.…”