Steel on Silicon Nitride Hybrid Tribological Systems Lubricated by Kerosene. Tests on a fFour-Ball Machine

Abstract

The kerosene can be used not only as a fuel for jet engines, but also as lubricant of the various mechanisms of modern jet aircrafts and turbine helicopters [1]. In order to determine the wear resistance of hybrid tribological systems lubricated by JET-A1 kerosene, accelerated tests of 1 minute were carried out on a four-ball machine at a constant speed of 1,500 rpm and variable load (from 500 N to 1,000 N). Steel and ceramic were selected as materials for the balls. The scuffing limit was detected at a load corresponding to about 4 GPa mean Hertz pressure and a sliding speed of 0.44 m/s on the concentrated contacts between the upper rolling bearing steel ball and the three lower silicon nitride balls. The diameters of the wear spots were measured on the lower ceramic balls and the structure of the worn surfaces was inspected by optical microscopy. Compared to previous results obtained for hybrid tribological systems lubricated by mineral oil [2], the kerosene film strength was found high enough to recommend it as a lubricant in mechanisms with hybrid concentrated contacts (e.g., hybrid ball bearings)