Mechanism Of Wear Protection Of Al-alloys Using XANES

Abstract

The mechanism of wear protection of Al-Si alloys in wear tests using lubricants containing Zinc dialkyl-dithiophosphate (ZDDP), Dialkyl dithiophosphate (DDP) , Amine phosphates, Thiadiazole, Antimony 0, 0-dialkylphosphorodithioate (SbDDP) was studied. Using techniques such as XANES this study examined the tribological behavior of these compounds and the characteristics of the tribofilms formed by them. High frequency reciprocating rig (HFRB) tests were conducted with lubricant containing these five antiwear additives were compared in both base oil and fully formulated oil. The tribofilms formed were then analyzed by a variety of techniques such as Scanning electron microscopy of the film and the composition was examined using EDS. The tribofilms were also chemically analyzed using X-ray absorption near edge structure (XANES) spectroscopy. Results indicate that the Al matrix does not assist in the formation of a tribofilms. However a transfer film formed from the steel ball and the lubricant chemistry on the precipitates provide protection on the surface. Lubricant chemistries that contain both S and P provide the best protection while the chemistries with either only P or S have very poor wear outcomes.