Interactions of fluorinated catalyst and polutetrafluoroethylene in two different plain zinc dialkyldithiophosphate oils and one fully formulated oil using design of experiment

Abstract

Friction and wear performance of engine oils in the presence of polutetrafluoroethylene (PTFE) and iron fluoride (FeF3) catalyst with plain zinc dialkyldithiophosphate (ZDDP) oils, and fully formulated oils were studied under extreme boundary lubrication (2.72 Hertzian contact load). Two brands of plain ZDDP oils with the same phosphorus percentages were used in the analysis. The study uses design of experiment (DOE) to analyse and optimise the fluorinated oil combinations, thus reducing phosphorus in both plain and fully formulated oils. High and low concentrations of fluorinated catalyst were optimised, and a (PTFE + catalyst) combination suitable for plain ZDDP oil and a fully formulated oil were studied using scanning electron microscopy, energy dispersive spectroscopy, wear profile analysis and tribosurfaces comparison. The experiment indicated that submicron FeF3 catalyst played an important role in preventing the breakdown of the tribofilm. The reduction of phosphorus in engine oil was examined. Very reproducible boundary lubrication tests with three replicates for each oil blend were conducted as part of the DOE software to study the behaviour of FeF3 catalyst and PTFE or Teflon in developing environmentally friendly (reduced P and S) anti‐wear additives for future engine oil formulations. Several responses with respect to sample failure and post‐wear measurements were analysed, and the overall desirability of the model was targeted to lower phosphorus blends. The goal of the model solution was to check the maximum and minimum interactions of PTFE and selected FeF3 catalyst with respect to both plain ZDDP oils and fully formulated oil.