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Abstract
The four-ball wear test is currently a mainstream method for assessing antiwear properties of lube oil. However, the assessment is normally based on a comparison of the final wear scar diameter and wear progressions cannot be well presented. A new experimental method for assessing antiwear properties of lube oil with near real-time (NRT) wear information was developed. Wear debris from a ball-on-disc tribometer under boundary lubrication was deposited by an online visual ferrograph (OLVF) every 6 min, and NRT information on wear debris generation rate was obtained. A mathematical model of the lubrication system serving the ball–disc tribopair was built, and an index of particle coverage area (IPCA) was approximately proportional to wear rate (by weight) of the ball–disc tribopair. IPCA curves characterized the antiwear performance of lube oil by three indictors, running-in duration, index of running-in wear amount, and index of steady-state wear rate. With the three indictors, a rule assessing the antiwear performance between two oils was proposed. Accordingly, wear tests of eight oils were performed, and their antiwear properties were distinguished by the assessment rule. Under the same setting, the assessing experiment of the same oil was conducted five times. According to the statistical analyses, the experimental method exhibited considerable repeatability.