Zinc Dialkyldithiophosphate-Dispersant Interactions: Effects on Solution Behavior and Wear 922282
Interactions between a Zinc dialkyldithiophosphate (ZDP) and three different commercially available succinimide dispersants were observed through changes in solutions behavior, as determined by viscometry and Fourier Transform Infrared spectroscopy (FTIR), and four-ball tests.
The viscometric response observed for two component blends of ZDP and succinimide dispersant in white oil changed as a function of the molar Zn to N ratio, indicative of specific interactions. The break in the viscometric response curve occurred at Zn:N=0.13 for all three succinimide dispersants. FTIR spectra of the same ZDP-dispersant blends were examined and similar Zn:N dependencies were observed.
Four-ball tests measuring wear scar diameter, seizure load and weld load showed a dependence on the Zn to N ratio similar to that observed by viscometry. At very low Zn to N ratios wear and seizure load were decreased, while at higher ratios the seizure and weld loads were increased over that for ZDP alone. These studies show that either ZDP-dispersant complexation and/or competition between the ZDP and the dispersant for the metal surface affects wear as measured by the four-ball test.
Citation: Kulp, M., Gundic, D., Hanna, M., and Fabian, L., "Zinc Dialkyldithiophosphate-Dispersant Interactions: Effects on Solution Behavior and Wear," SAE Technical Paper 922282, 1992, https://doi.org/10.4271/922282. Download Citation
M. J. Kulp, D. T. Gundic, M. E. Hanna, L. E. Fabian
The Lubrizol Corp.
International Fuels & Lubricants Meeting & Exposition
Rheology and Tribology of Engine Oils-SP-0936, SAE 1992 Transactions: Journal of Fuels & Lubricants-V101-4