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Abstract
A sequential four-ball wear test has been developed to study the chemical changes that take place in boundary or mixed film lubrication. In the first sequence, the 52100 steel balls are mated by a 60-minute run-in at 40 Kg load under fully flooded conditions using a 78 centistoke at 40°C white oil. The second segment of the test is run with up to five microliters of the desired lubricant. Lubricant failure in this sequence is defined as a sharp rise in friction, indicating a lack of lubricant supply to the conjunction. Lubricant changes resulting in the failure are determined by a gel permeation chromatography (GPC) analysis of the lubricant at the time of failure compared with the GPC analysis of the new lubricant used, in the lest. Failure appears to occur where the degraded lubricant becomes too thick to flow into the conjunction. In most cases, a relatively small amount of severely oxidized lubricant forms a grease-like mixture containing a relatively large amount of un-reacted. lubricant. The life of lubricants in these tests appears to be dependant, on the reactions driven by frictional heating that take place between the lubricant, dissolved oxygen, and the bearing surface.
Presented as a Society of Tribologists and Lubrication Engineers paper at the ASME/STLE Tribology Conference in Toronto, Ontario, Canada, October 8–10, 1990
Notes
Presented as a Society of Tribologists and Lubrication Engineers paper at the ASME/STLE Tribology Conference in Toronto, Ontario, Canada, October 8–10, 1990