Liquid Phase Adsorption/Reaction Studies of Organo-Sulfur Compounds and Their Load-Carrying Mechanism

The liquid phase adsorption and reaction of a range of organo-sulfur compounds with ground iron powder were studied in the temperature range 25–170 C. The reactivity of organic disulfides was found to increase along the series: Monosulfides and mercaptans were found to be less reactive than the corresponding disulfides. A mechanism of reaction of these organo-sulfur compounds with the metal surface has been derived. This mechanism has confirmed the authors' earlier proposed mechanism of load-carrying action of organo-sulfur compounds as extreme pressure (EP) additives, but has resulted in a modification of the authors' proposed mechanism of antiwear (AW) action of these additives. This study has also indicated the temperature at which organo-disulfides function as EP additives. Presented as an American Society of Lubrication Engineers paper at the ASME/ASLE International Lubrication Conference held in New York City, October 9–12, 1972