A theoretical investigation on the abrasive wear prevention mechanism of ZDDP and ZP tribofilms

We investigated wear prevention mechanism of tribofilms generated from zinc dialkyldithiophosphate (ZDDP) and zinc dialkylphosphate (ZP) anti-wear additive using molecular dynamics simulations. The friction behavior of two model materials, zinc metathiophosphate and zinc metaphosphate, was studied. The results indicated that zinc metathiophosphate prevents the abrasive wear due to the atomistic digestion of the wear particles in the tribofilm. We also investigated wear prevention mechanism of zinc metaphosphate and found that it has a better wear prevention performance than zinc metathiophosphate as far as abrasive wear is concerned. Our study showed that zinc metaphosphate can achieve good wear prevention and reduce the environmental load since it does not contain sulfur.