ABSTRACT

Τρίτη 29 Σεπτεμβρίου 2009
Αίθουσα Σεμιναρίων «Ν. Κουμούτσου»

Dr. Jean-Pierre Celis(1) and Dr. Pierre Ponthiaux(2)

(1) Katholieke Universiteit Leuven, Dept. MTM, Leuven, Belgium
(2) Ecole Centrale Paris, Lab LGPM, Châtenay-Malabry, France

Mechanical and electrochemical aspects of tribocorrosion in the case of passivating metallic materials immersed in aqueous solutions

One of the basic limitations in studies on the frictional behavior of solid materials is linked to the lack of experimental information on :
- the initial contact conditions on the surfaces of the first bodies,
- the determination of the real contact area on each first body,
- their evolution during test duration,
- the local and instantaneous value of the coefficient of friction.
These facts limit the identification of the time- and space-evolving phenomena that take place at the interface between the contacting first bodies, and their interaction on friction. The search for answers to these questions requires thus an approach based on different disciplines that can clarify the in-situ conditions in a metal-to-metal sliding contact.

When such a sliding contact between metallic materials is immersed in a more or less aggressive environment like polluted ambient air in cities, industrial polluted fields, or in a marine environment, one has to consider, additionally to the points raised here before, aspects of data acquisition on these environments and on the possible modifications induced commonly by chemical and electrochemical reactions at the metal surfaces in contact with an aqueous corrosive environment.

Tribocorrosion is a degradation process, e.g. due to mechanical deformation or cracking, and the wear of metallic surfaces resulting from a combined effect of friction and physicochemical phenomena like oxidation, corrosion, hydrogen embrittlement. Tribocorrosion deals with the study of the nature and the modifications of the friction mechanisms induced by the aggressiveness of the environment and the mechanical loading. Tribocorrosion aims at answering in a multi-disciplinar approach the relationships between Surfaces-Environment-Sliding Contacts.

In this lecture an overview will be given on the actual insights into the different processes that are active during tribocorrosion, the ways how tribocorrosion can be investigated at lab scale both in-situ and ex-situ. A description of the process of tribocorrosion opens the way to a modeling based on friction and wear laws experimentally determined.