Three-Body Abrasion Study of a Dynamic Seal by a Micro-Scale Abrasion Test under Lubricated Conditions

Debris are progressively generated just after wear occurred by the interaction of various mechanical elements inside the engines, steering gear boxes, transmissions, differentials, etc. Besides, debris could interfere with the normal operation of such components generating even more damage in other parts due to three-body abrasion. Hence, dynamic seals are susceptible to interact with very fine debris accumulated in the working lubes. Recently, owing to many test advantages, the micro-scale abrasion test has been extensively used to reproduce three-body abrasion in hard materials, coatings, polymers, etc., however, it has not been before employed for the wear assessment of elastomeric materials. This paper presents an adaptation of the micro-scale test method to study three-body abrasive behavior of an elastomeric dynamic seal (samples extracted from an automotive commercial Acrylonitrile-butadiene NBR rotary seal) under lubricated conditions. This work looks generate three-body abrasion on the NBR material, proposing a range of test conditions (Load, sliding speed, sliding distance and abrasive concentration) and quantify the volume loss. Engine lubricant contaminated with SiC micro-particles was used toward replicating the actual seal lip-rotary shaft interface condition. According to SEM images from the wear scars, the wear mechanisms were polishing (two-body abrasion), three-body abrasion, and a mixture of them. Nevertheless, three-body abrasion was just obtained under specific conditions. Finally, the particular wear pattern of three-body abrasion of elastomers was achieved. Even more, the method should be potentially used to test any elastomeric material in order to characterize the three-body abrasion resistance.