Wear Mechanisms Arising Additives Based Ceramic Particles to Automotive Lubricants

Abstract

Estimated that one third of the world’s energy will be consumed by friction, as most machine elements and vehicles have failed due to excessive wear. The increase of the load-lubricant ratio has caused adverse effects on the friction and wear of the components, therefore the regulation of emissions levels. The evolution of lubricating oils and additive technologies will be a major technological effort to improve fuel economy, reduce pollutant emissions and extension of drain interval. The unique properties related to low weight, high hardness, thermal stability and chemical inertness are the divergence of ceramics particles in relation to other engineering materials, and are being considered as an alternative for future tribological applications. In this article was studied the effects by the addition of modified submicrometric particles of ZnO and Al2O3 separately in mineral base stock (group I) for replacing the traditional ZDDP additive. The tests were performed of according ASTM D4172 in Four Ball tribometer with three load levels, and the wear characteristics of the steel ball as well as the incorporation of particles in the wear scar were analyzed by optical and scanning electron microscopy. The function and mechanism performance of additives based submicrometric particles during operation, such as mending, rolling, film formation and polishing effect. The excellent load carrying capability of particles during lubrication evidence their outstanding performance. Increasing the loads during tribological tests, it was noted that the wear mechanisms with the ZDDP initially caused plastic deformation and corrosive wear with carbides exposure, while the addition of ZnO particles caused lightened abrasive wear with some removal of carbides and finally an intense plastic deformation. The colloidal lubricant with Al2O3 particles caused the same wear mechanisms, but on the wear scar presents points of surface delamination. The ceramic additives added to the mineral base stock result in a wear mechanism that benefits the tribological behavior for different lubrication regimes. Considering also that the particles on a nanometric or submicrometric scale are a type of effective additives which promising approach to enhance in the biodegradable lubricant properties.

Keywords

• wear
• mechanisms
• lubricant
• particle
• zddp