Perpustakaan Digital ITB

Used lubricating oil contains more than 90% of good base oil and available additives, providing the potential of energy conservation, environmental protection, and economy, though it loses its useful performance because of contamination by impurities, oxidation, and degradation of additives. Many countries around the world have focused on reclamation and rerefining methods to treat and reuse waste lubricating oils for many years. But the regeneration rate of waste oils is very low in China, less than 20% of the lubricant consumption. Few studies on the performance, especially lubrication properties of recycled lubricating oils, have been considered. In this article, based on differences between used and fresh oils, used oils were reclaimed and replenished with additives (henceforth refortified oils). The physical and chemical properties, including viscosity, total acid number, moisture content, copper corrosion, and water separability from petroleum oil and synthetic fluid as well as the lubrication characteristics of three kinds of refortified hydraulic oils were investigated. The lubrication performance was evaluated using a four-ball tribotester and a Universal Micro-Tribotester (UMT) reciprocating tester. Moreover, the worn surfaces were analyzed using confocal scanning optical microscopy (CSOM), scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS), and Raman spectroscopy. The results showed that refortified oils provided good physical and chemical properties, close to those of fresh oils, and produced better tribological characteristics than used and even fresh oils. There were compositional differences between the films of fresh, used, and refortified oils.