An overview on the tribological behavior of diamond-like carbon in technical and medical applications

Review of the lubrication of metallic surfaces by zinc dialkyl-dithiophosphates

The role of zinc polyphosphate in the antiwear mechanisms of zinc dithiophosphate (ZDDP) is investigated in the light of recently published analytical data carried out on thermal films and tribochemical films obtained from the additive. Special attention is paid to explaining the mechanisms of the polyphosphate in eliminating abrasive wear due to the presence of transition metal oxide species in boundary lubrication. A set of tribochemical reactions between the polyphosphates and the oxides is proposed on the basis of the hard and soft acids and bases (HSAB) principle. The antiwear action of ZDDP is found to be very adaptive and in severe conditions, the model predicts a layered tribofilm with the presence of polymer-like zinc metaphosphate overlying a mixed-transition-metal phosphate glass, in good agreement with recent analytical data. The role of residual sulphur in the lubricant is also envisaged and the model is in agreement with the formation of metal sulphides embedded in the phosphate matrix. The model, based on the chemical hardness concept, could be used as a basis for the prediction of interactions between ZDDP and other additives in motor oils.

Antiwear mechanisms of zinc dithiophosphate: a chemical hardness approach

Application of soft X-ray absorption spectroscopy in chemical characterization of antiwear films generated by ZDDP Part I: the effects of physical parameters

Boundary lubricating films: formation and lubrication mechanism

Mechanism of formation of antiwear films from zinc dialkyldithiophosphates

The composition of lubricant-derived surface layers formed in a lubricated cam/tappet contact II. Effects of adding overbased detergent and dispersant to a simple ZDTP solution

The frictional behavior of two oils was measured in a cam/tappet friction apparatus using a direct acting bucket tappet geometry. One oil contained a soluble molybdenum friction modifier. The films consisted of varying amounts of inorganic phosphates, sulfates and sulfides with zinc, magnesium, and possibly molybdenum as cations. MoS 2 , expected because additives containing molybdenum and sulfur were present, was not detected

R.O. Carter

Papers

Mechanism of formation of antiwear films from zinc dialkyldithiophosphates

The composition of lubricant-derived surface layers formed in a lubricated cam/tappet contact II. Effects of adding overbased detergent and dispersant to a simple ZDTP solution

The Composition of Surface Layers Formed in a Lubricated Cam/Tappet Contact

Characterization of films formed at a lubricated cam/tappet contact