Post-mortem mechanical properties

The role of antiwear additives in boundary lubrication has been mentioned briefly in the general presentation (Section 1). The way in which zinc dithio-phosphate (ZDDP) acts as an antiwear additive is almost certainly that of the elimination of the abrasive wear contribution of crystallized iron oxide species as a result of their tribochemical reactions with the additive molecules and/or various degradation products. The use of XAS and TEM/EELS together with complementary CEMS and AES represents a powerful analytical combination for the elucidation of the tribochemical reactions responsible for antiwear mechanisms. The first part of this section summarizes analytical results obtained with friction tests carried out in the ambient atmosphere. The second part describes some original results obtained with friction tests and in situ post mortem AES analysis in ultrahigh vacuum. In this way the intrinsic frictional properties of the solid reaction film itself, without the effect of the environment, and the ability of friction to modify the nature and the structure of the surface films are investigated. 

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