20.500.12556/RUL-169952 Perfluorotetradecanoic acid as an additive for friction reduction in full-film EHD contacts the role of functional group, base oil polarity, additive concentration and contact pressure Perfluorinated tetradecanoic acid was added as an additive to a base oil and tested under full film elastohydrodynamic (EHD) contact conditions between a steel ball and a steel disc. By varying key performance parameters, we aimed to assess the feasibility and limitations of perfluorinated carboxylic acids in reducing friction in lubricated contacts. The results demonstrate that the tested perfluorinated additive is effective in reducing friction when blended with a non-polar synthetic poly-alpha-olefin oil. However, no significant friction reduction was observed when the same additive was used in a slightly polar synthetic ester. The carboxylic acid functional group plays a crucial role in the observed friction-reducing effect. Adjusting the additive concentration further plays an important role in reducing friction. A concentration of at least 0.35 wt.% is required to achieve a notable friction reduction of approximately 10%. Increasing the concentration beyond this threshold continues to improve the friction-reducing effect. Conversely, increasing the contact pressure has a detrimental impact on friction reduction. The greatest reduction in friction—over 20% compared to the base oil—was achieved at the lowest contact pressure tested (0.69 GPa). additives EHD contact base oil concentration pressure aditivi EHD kontakt bazno olje koncentracija tlak true false true Angleški jezik Slovenski jezik Članek v reviji 2025-06-26 11:28:56 2025-06-26 11:29:01 2025-06-27 03:54:55 0000-00-00 00:00:00 2025 0 0 12 str. issue 6, art. 263 Vol. 13 2025 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 539.92 2075-4442 10.3390/lubricants13060263 240516611 RAZ_Polajnar_Marko_2025.pdf RAZ_Polajnar_Marko_2025.pdf 1 E64A1979FAB68882B11E70372776C321 70415ccaf4697d8d2dcdbdd3042151e550ebe43b2b0f39d41783d9812b606476 63c87083-526f-11f0-b232-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=211783 https://www.mdpi.com/2075-4442/13/6/263 1 1fb4855b-526e-11f0-b232-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=211781 Fakulteta za strojništvo 0 0 0