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.