The friction properties of wet clutches are highly dependent on the surface tribofilms formed by automatic transmission fluids (ATFs). Here, four commercial ATFs were evaluated with a disc-on-disc tribometer to study tribofilm formation on steel surfaces and the effects of tribofilms on the friction properties. The chemical composition, stoichiometry, structure, and thickness of the tribofilms were investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX), secondary ion mass spectrometry (SIMS), and X-ray photoelectron spectroscopy (XPS). Calcium phosphate (CaP) tribofilms form on the friction surface with all ATFs, which contributes to their antishudder characteristics. The thickness and surface coverage of CaP tribofilms are positively correlated with their antishudder properties.
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The authors are grateful to the Petrochina Company Limited for financial support.
Zechao DI. She received her Ph.D. degree in mechanical engineering in 2006 from Tsinghua University, Beijng, China. She joined Lubricating Oil Research & Development Institute of PetroChina from 2007. Her research areas cover the friction and lubrication of automotive automatic transmission fluid.
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Di, Z., Xu, J., Liu, Y. et al. Investigation of calcium phosphate (CaP) tribofilms from commercial automatic transmission fluids (ATFs) and their correlation with antishudder performance. Friction 8, 882–892 (2020). https://doi.org/10.1007/s40544-019-0305-3
- commercial ATF