Temperature dependence of molybdenum dialkyl dithiocarbamate (MoDTC) tribofilms via time-resolved Raman spectroscopy

Abstract Molybdenum dialkyl dithiocarbamate (MoDTC) is a friction reducing additive commonly used in lubricants. MoDTC works by forming low-friction molybdenum disulphide (MoS 2 ) film (tribofilm) on rubbed surfaces. MoDTC-induced MoS tribofilms have been studied extensively ex-situ ; however, there no consensus the chemical mechanism of its formation process. By combining Raman spectroscopy with tribometer, effects temperature and shear stress tribofilm steel-steel contacts were examined. Time-resolved spectra acquired , together instantaneous coefficient. The constantly being formed removed mechanically during rubbing. Increasing promotes formation. nature temperature-dependent, high-temperature giving higher than lower films. Below critical T c small amount gives significant reduction. Above c, patchy more substantial amorphous carbon attributed to base oil degradation, forms. composition this evolves rubbing temporal correlation found between signal intensity friction. Our results highlight mechanochemical process role degradation effectiveness modifier MoDTC.