On the role of plastic deformation during the mild wear of alumina

✍ Scribed by J.D.O. Barceinas-Sánchez; W.M. Rainforth

• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 423 KB
• Volume: 46
• Category: Article
• ISSN: 1359-6454
• DOI: 10.1016/s1359-6454(98)00292-4

✦ Synopsis

AbstractÐPolycrystalline a-alumina was worn against Mg-partially stabilized zirconia (Mg-PSZ), using water lubrication, a sliding speed of 0.24 m/s and a load of 10 N. Dierential wear between grains (maximum H33 nm) and ®ne (0.3±1.9 mm diameter) abrasive grooves were found on the worn surface. TEM of back-thinned samples indicated widespread dislocation ¯ow at the surface, heterogeneously distributed between grains, and largely associated with abrasive grooves. Those grains standing proud of the surface invariably contained extensive dislocation damage. The dominant slip system was pyramidal (f1 1 2 3g, f2 1 1 2g, f1 0 1 2g and f1 0 1 1g) although occasional 0 0 0 1 basal slip was also found. No prism slip was observed. The pyramidal slip planes were concentrated at angles of H6±338 to the worn surface. Basal slip was frequently associated with basal twinning on planes at H72±738 to the worn surface. Dislocation pileups at grain boundaries often coincided with grain boundary cracking. The extent of damage from abrasive grooves varied from grain to grain and was dictated by crystallographic orientation more than the grain height. No evidence of mechanical damage was found in those grains that had suered the highest wear, indicating that material removal had been controlled by tribochemical mechanisms. The origin of the dierential wear between grains is considered and the implications of the experimental observations on the time-dependent transition to severe wear in aluminas are discussed.