Corrosion-wear of passivating materials in sliding contacts based on a concept of active wear track area

The concept of active wear track area is proposed as a way to investigate t he mechanism of the corrosion-wear behavior of passive materials under slid ing conditions. This active wear track area represents that part of the wea r track that looses temporarily its passive character due to the mechanical interaction during sliding. It is shown that the active wear track area ca n be determined from repassivation kinetics measured on electrochemically a ctivated material by a potential pulse method, and from anodic currents mea sured during sliding ball-on-disk tests. The use of that concept is illustr ated for the case of stainless steel AISI 316 immersed in a 0.5 M H2SO4 sol ution. At loads below 2N, no breakthrough of the oxide film is noticed. At loads between 2 and 12N, the corrosion-wear agrees well with Quinn's mild o xidation wear mechanism. The corrosion-wear of ATSI 316 consists then of tw o processes namely a mechanical delamination of the passive layer in part o f the wear track, followed by a progressive electrochemical re-passivation of that active wear track area. The thickness of the passive layer on AISI 316 was derived from the active wear track area and the electrochemical res ponse of passive and active AISI 316 material. A value of 2-3 nn was obtain ed that agrees well with data obtained by other methods. Above a load of 12 N, the corrosion-wear increases steeply due to a degradation process involv ing abrasion and/or breakdown of more than just the oxide film. (C) 2001 El sevier Science B.V. All rights reserved.d