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

The application of photoelectron spectroscopy to the study of e. p. films on lubricated surfaces

The antiwear mechanism of zddp's. Part II

Oil-soluble MO-S compounds as lubricant additives

The oil-soluble degradation products formed in heated samples of oil containing zinc di(n-, iso- or s-butyl)dithiophosphate (ZDTP) additives have been identified using 1H and 31P nuclear magnetic resonance spectroscopy. The final degradation product in each case is S,S,S-trialkyltetrathiophosphate, SP(SR)3. The intermediate degradation products are O,S,S-trialkyltrithiophosphate, SP(SR)2(OR) and O,O,S-trialkyldithiophosphate, SP(SR)(OR)2. The rate of thermal degradation of the ZDTPs follows the order s-butyl > > n-butyl > isobutyl. A white, noncrystalline precipitate is formed in the heated oils which is rich in zinc and oxygen and low in phosphorus and sulfur compared with the original ZDTP. In four-ball tests, synthesized degradation products were shown to have EP activity comparable with that of the ZDTP additives. Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference in Dayton, Ohio, October 16–18, 1979

The Thermal Degradation and EP Performance of Zinc Dialkyldithiophosphate Additives in White Oil

Glancing angle X-ray diffraction, electron probe micro-analysis, scanning electron microscopy, and optical microscopy combined with sectioning and microhardness testing, have been used to identify surface layers produced on En31 (A1SI 52100) steel specimens by a series of organic disulfides and two dialkyldithiophosphates in wear tests. It is shown that the combined use of these techniques gives much more information than the use of any single one. The findings are discussed in relation to current theories of the action of extreme pressure lubricants. Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Montreal, Canada, October 8–10, 1974

T. F. J. Quinn

Papers

The Use of Physical Methods of Analysis to Identify Surface Layers Formed by Organosulfur Compounds in Wear Tests