Radiosulfur Tracer Study of Sulfurized Lubrication Addition Agents

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Abstract
Radioactive tracer techniques have been used to ascertain the concentration of sulfurized addition agent in lubricating oil blends on metallic surfaces, the active element being radiosulfur prepared with the cyclotron and introduced into the olefin molecules. Film formation seems to be quite general, having been tested on seven different types of commercial metallic bearings as well as on glass. The film is transparent and very thin. In the extreme cases, it imparts a faint opalescence to the bright surface. The organic molecules may form a loose molecular compound with the metal or a polymerized film, sufficiently adherent, however, to resist the solvent action of benzene and carbon disulfide. The rate of film formation has been established at 88°C (190°F) and at room temperature for a typical bearing composition. It has been found that the rate though several times slower than at 88°C at room temperature is still quite appreciable and favorable from the standpoint of engine protection. The mechanism of oxidation inhibition and thus retardation of corrosion and sludging with this addition agent seems to embrace both alteration of surface character of catalyzing metals and bulk or liquid phase inhibition in the oil. The adherent organic film is probably involved in ``oiliness'' (film strengthening and prevention of complete oil drainage from motor bearings and walls by anchoring through polar molecules) since engine tests have shown that the oiliness of straight mineral oil is appreciably improved by addition of sulfurized olefins.