Effect of alloying elements and fatty acid on tribocorrosion of stainless steel in water based hydraulic fluids

摘要

In marine applications mineral-based hydraulic fluids are vastly used and exposed to harsh offshore conditions, however their flammability and negative impact on environment has shifted interest to novel water-based fluids. Water-ethylene glycol based hydraulic fluids showed promising biodegradability, low flammability and cooling capabilities. A previous research by the authors on positive influence of fatty acids, showed the importance of molybdenum interaction with fatty acids to form a stable 30-70 nm tribofilm that highly reduces wear loss in tribocorrosion of austenitic stainless steel. This study focuses on the tribocorrosion response of the molybdenum (as an alloying element in stainless steel) in formation of a stable and low shear protective tribofilm at different electrochemical conditions in water-ethylene glycol based lubricants. Tribocorrosion test are to be performed at different electrochemical conditions (cathodic, open circuit and passive potentials). X-ray photoelectron spectroscopy facilitates through investigation of surface chemistry and depth profiling while grain refinement and tribofilm mechanical characteristics are investigated by focused ion beam and scanning electron microscope.