Opportunities for Replacement of Phosphorus and Dithiophosphates in Lubricating Oil With Borate Ester Additive Containing Nitrogen

The poisoning of exhaust catalysts by phosphorus has lead to research to provide new additives packages to reduce or displace the use of ZDDP. In this research a four-ball tester was used to evaluate the tribological performances of organic borate ester containing nitrogen (BNO) combined with zinc dialkyldithiophosphate (ZDDP) or tin dialkyldithiocarbamates (SnDDC) in base oil respectively. The results indicate that the combination of these additives with organic borates ester can exhibit better antiwear synergism than either component separately without impairing load carrying abilities. Especially, the antiwear properties of oils can be improved significantly under optimal concentration ranges. Accordingly considerable amount of or ZDDP can be partially replaced by BNO in synergetic mixtures, or replaced completely by the combination of BNO with SnDDC. This might provide opportunities for the use of lower concentrations of S, P additives.