Antiwear synergism of borates and cadmium diamyldithiocarbamate

Certain combinations of an oil-soluble cadmium compound, e.g., cadmium diamyldithiocarbamate, with organo-borates, either sulphurised or nonsulphurised, give better antiwear performance than do the individual components. A synergistic mechanism is postulated, in which boron atoms with vacant p orbitals catalyse triboreduction of cadmium on rubbing surfaces, producing elemental cadmium. The cadmium deposits on, and alloys with, the metal surface to protect the substrate against wear.