Application of the ASTM loop abrasion test to cylindrical specimens

The loop abrasion test (based on ASTM G 174-03) was modified to accommodate cylindrical specimens in place of the usual flat specimens. Hardened AISI 52100 steel, a galling-resistant stainless steel (Nitronic 50), transformation- toughened zirconia ceramic, and an advanced composite containing Ni ₃Al and TiC (cermet) were used to validate the new testing geometry. The weight change and the scar width were measured, and the calculated wear volumes for each metric were compared with very good correlation. Each test was interrupted periodically in order to determine the effect of sliding distance on the wear rate. In general, a higher wear rate was observed during wear-in followed by a nearly constant steady-state wear rate. The initial high wear rate was contributed primarily by the fresh abrasive and secondarily by the high contact stress. The loop abrasion test has good repeatability and sensitivity for ranking materials. The abrasion resistance of both the cermet and the zirconia was much higher than that of Nitronic 50 and hardened 52100 steel. Even though the hardness of the cermet is lower than zirconia, it had the highest abrasion resistance in this study. Comparative tests on cylindrical and traditional flat specimens (per ASTM G 174-03) showed similar wear behavior with slightly higher wear rate for the cylindrical specimens due to higher contact stress.