Synthetic metallic dialkyldithiocarbamates as antiwear and extreme-pressure additives for lubricating oils : role of metal on their effectiveness

Abstract

Dialkydithiocarbamates of five metals have been synthesized in pure form by following a simple general method. The alkyl chain in each of these compounds has been kept the same so as to observe the performance variations due to metal ions. The EP properties expressed as load wear index and weld load indicated the highest performance by Bi followed by Pb, Sb, Zn and Mo. The antiwear properties in terms of wear scar diameter, relative anti-wear effectiveness and mean average wear scar diameter show a performance order of Bi > Pb > Sb > Zn > Mo. The large ionic radius metals (Bi, Pb & Sb) had the best overall load-carrying performance and their effectiveness increased substantially when the additive concentration was more than 0.004 gm atom/Kg. The results suggest that Bi has good potential to replace toxic Pb and Sb from existing lubrication systems. 18 refs., 7 refs., 1 tab.