Mechanical Properties of ZnDTP Tribofilms Measured by Nanoindentation at Controlled Temperature

Zinc dialkyldithiophosphates (ZnDTPs) are known to be anti-oxydant and antiwear additives under boundary lubrication conditions and are thus extensively used for car engine lubrication. It was demonstrated that their anti-wear action is associated with the formation of a protective tribofilm on the rubbing surfaces. In this study, mechanical properties of a ZnDTP tribofilm were measured by nanoindentation at various temperature ranging from room temperature to 80°C. From these first tests, it was found that the hardness of the tribofilm measured at 80°C is half the hardness value measured at room temperature, while the Young’s modulus remains constant in the tested temperature range.