The Nature of Electrochemical Reactions Between Several Zinc Organodithiophosphate Antiwear Additives and Cast Iron Surfaces

Abstract

This printing supersedes the publication in the July, 1988 Tribology Transactions pages 382-390 in which Fig. 16 and Table 5 were omitted along with the Discussion and Closure.

The electrochemical reactivities of four commercial zinc organodithiophosphate (ZDP) antiwear additives, each blended with a common mineral oil, were measured during thermal decomposition tests.

The results imply that electrochemical reactions between the decomposition products of ZDP and the electrode surfaces produce surface coatings on cast iron electrodes.

This observation suggests that electrochemical methods might be useful tools for understanding the mechanism by which ZDPs reduce wear. The electrochemical reactivity of the blends was proportional to the thickness of surface coatings formed on the electrodes at the end of the test, and inversely proportional to the ZDP's decomposition temperatures. The effects of oxygen, oleic acid concentration, and surface coating on the electrochemical reactivity were measured.

Presented as a Society of Tribologists and Lubrication Engineers paper at the STLE/ASME Tribology Conference in San Antonio, Texas, October 5–8, 1987

Notes

Presented as a Society of Tribologists and Lubrication Engineers paper at the STLE/ASME Tribology Conference in San Antonio, Texas, October 5–8, 1987