Tribological behavior of some antiwear additives in vegetable oils

There has been a growing concern for the use of mineral oils because of the worldwide interest in environmental issues, This has promoted the use of vegetable oils as the alternative base fluids, environmental friendly lubricants, In view of this, a study of the effect of antiwear additives in vegetable oils was carried out using a four-ball wear tester. The newly synthesized additive, dibutyl 3.5-di-t-butyl 4-hydroxy benzyl phosphonate (DBP) showed excellent antiwear performance compared with the conventional additive, TCP, under high speed and temperature conditions. To investigate the scavenging role of free hydrogen radicals of the DBP additive, a thermal degradation test was conducted to identify physico-chemical reactions using a differential scanning calorimeter (DSC). The surface analysis of worn balls was carried out using an optical microscopy and EDAX. On the basis of the experimental results, the new additive showed the dual function of hydrogen scavenging and protective film formation, and was found to be a effective antiwear additive in various lubrication systems. (C) 1998 Published by Elsevier Science Ltd.