WEAR BEHAVIOR OF BASE OIL FRACTIONS AND THEIR MIXTURES

Nine nominal 100 neutral base stocks, comprising a wide range of crude origins and refining processes, were separated via silica gel chromatography into aromatic, saturate, and polar fractions. These hydrocarbon and polar fractions, along with their mixtures were evaluated for wear characteristics in steellsteel reciprocating point tribocontact at 25 and 100°C temperatures. Overall, the saturate fractions give lower wear rates than their parent base stocks and the aromatic fractions. Increased refining of base stocks, as measured by decreasing polar or sulfur contents, is seen to deteriorate the wear characteristics of the aromatic fractions, whereas the saturate fractions are not affected much. Aromatic saturate mixtures, especially those from some model compounds, exhibit synergistic effects for wear. Polar compounds extracted from solvent extracted stocks increase wear but decrease friction, especially at high concentration. All test data are analyzed and discussed with emphasis on the influence of base stock chemical composition and structure of compounds on wear characteristics. © 1990 Taylor & Francis Ltd.