A STUDY IN THE TRIBOCHEMISTRY OF ALKYLDITHIOBIURETS AND THEIR MO-S COMPLEXES AS EP ADDITIVES

0.5% solutions of 1-alkyl-2,4-dithiobiuret ligands and their Mo-S comp lexes i.e. o-mu-(1-alkyl-2,4-dithiobiureto)-bis-[dioxohydroxo molybden um-(VI)] in paraffin oil were found to significantly reduce wear and f riction of 12.7 mm diameter steel balls in a four-ball test. In partic ular, the additive 4-dithiobiureto)-bis[dioxohydroxo-molybdenum-(VI)] was found to exhibit an appreciable increase in the load carrying capa city of the lubricant and a decrease in the values of coefficient of f riction. The additive ,4-dithiobiureto)-bis[dioxohydroxo-molybdenum(VI )] was also found to be effective at high speeds. The topography and t ribochemistry of the used ball specimens were examined by means of sca nning electron microscopy and scanning auger electron spectroscopy tec hniques, respectively. (C) 1997 Elsevier Science S.A.