RELIABILITY OF WEAR VOLUME MEASUREMENT APPROACHES IN RELATION TO THE EFFECT OF SURFACE FINISH ON FRICTION AND WEAR OF AL2O3

Wear measurements are notoriously variable. Even the experiments with the same type of material and test machine can give significantly diff erent results. Such discrepancies are mostly due to a lack of adequate control of test conditions and unreliable measurement techniques. Spe cification and control of certain tribological quantities are a necess ary prerequisite of obtaining reproducible and comparable results. To proceed forward in this direction, it is essential to review and analy ze the existing test procedures and measuring techniques. In this stud y, the authors investigated the reliability of the most common wear vo lume measurement approaches and explored the influence of surface fini sh on the friction and wear performance of Al2O3 ceramics. The wear te sts were performed with a pin-on-disc machine on polished and ground s urfaces of Al2O3 disks. The wear volume was measured from height displ acement, weight loss, and from worn surface profilometry. The results indicated that the wear volume measurements by surface profilometry an d height displacement (by transducer) were highly reliable. The wear r ates of ground and polished alumina were in the order of 10(-7) mm(3)/ m . N. Finally, for the specific surface roughness range (Ra = 0.03 to 0.4 mu m) explored in this study, the surface finish was only importa nt during the initial run-in period.