Effects of oleophobic coated non-contact seals on grease and oil leakage

This study investigates the effectiveness of oleophobic fluorocarbon coatings in reducing oil and grease leakage through shielded shafts equipped with non-contact (gap) seals. Three different coatings were applied to both shield and shaft surfaces. Surface energy properties, including polar and dispersive components, were measured and correlated with molecular structures analyzed using Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Photoelectron Spectroscopy (XPS). A simple Molecular Dynamics (MD) simulation provided insights into the wettability and interfacial energies. Experimental leakage tests with a mineral oil and two lithium-based greases were conducted using a laboratory setup (Pearl rig). A simplified leakage model based on capillary action was developed and validated against experimental results. The findings show that oleophobic coatings substantially reduce leakage, in agreement with the model’s predictions.