TRIBOLOGICAL BEHAVIOR OF SOME ANTIWEAR ADDITIVES IN VEGETABLE-OILS

There has been a growing concern for the use of mineral oils because o f the worldwide interest in environmental issues, This has promoted th e use of vegetable oils as the alternative base fluids, environmental friendly lubricants, In view of this, a study of the effect of antiwea r additives in vegetable oils was carried out using a four-ball wear t ester. The newly synthesized additive, dibutyl 3.5-di-t-butyl 4-hydrox y benzyl phosphonate (DBP) showed excellent antiwear performance compa red with the conventional additive, TCP, under high speed and temperat ure conditions. To investigate the scavenging role of free hydrogen ra dicals of the DBP additive, a thermal degradation test was conducted t o identify physico-chemical reactions using a differential scanning ca lorimeter (DSC). The surface analysis of worn balls was carried out us ing an optical microscopy and EDAX. On the basis of the experimental r esults, the new additive showed the dual function of hydrogen scavengi ng and protective film formation, and was found to be a effective anti wear additive in various lubrication systems. (C) 1998 Published by El sevier Science Ltd.