Effect of sulfur-containing additive on the decomposition of multialkylated cyclopentane oil on the nascent steel surface

The role of di-tert-dodecyl disulfide as an additive in the decomposition process of hydrocarbon oil on the nascent surface of bearing steel 52100 was investigated by a ball-on-disk friction tester in a vacuum chamber with a quadrupole mass spectrometer (Q-MS). After the formation of a nascent surface, hydrogen and gaseous hydrocarbons desorbed as tribochemical reaction products. The desorption rate of gaseous hydrocarbons decreased significantly when the additive was introduced. The additive prolonged the induction period of the decomposition. XPS and ToF-SIMS analysis revealed that additive molecules and lubricant molecules competitively chemisorbed on the nascent surface and reaction occurred by the formation of iron sulfide, which poisoned the catalytic activity of active sites leading to deactivation. As a result, decomposition of hydrocarbon oil decreased significantly. (C) 2009 Published by Elsevier B.V.