Degradation of metallic (bio)materials: synergic effects of corrosion/friction/wear

At the end of the module, students will be able to predict and prevent the degradation of metallic materials under mechanical contact stress and/or corrosion by a surrounding environment.

Teaching objectives

The degradation of metal parts in contact and in relative movement placed in a corrosive environment is often of a mechanical and/or chemical type. These degradations can affect the integrity and the functioning of systems and machines including metallic parts subjected to a severe environment. Many industrial sectors are concerned by the prediction and prevention of these degradation mechanisms: automotive industry, oil industry, food industry, nuclear industry, transportation, and even biomaterials engineering and the health sector.

In this module, we will focus on the in-service damage of metallic materials by friction or corrosion. These two mechanisms, which can also be combined, are grouped together under the term tribocorrosion, an aspect also introduced in this module.

The analysis and control of these degradation modes are based on a multidisciplinary approach including notions of mechanics, materials science, electrochemistry and biology. They also require the development of specific friction tests in a corrosive environment, combining tribological techniques and electrochemical methods of studying corrosion.

The main objectives of this module are therefore :

    The understanding and control of the mechanisms of friction and wear (tribology).
    The understanding of the main mechanisms of corrosion in a wet environment.
    The study and understanding of coupled phenomena: stress corrosion and tribocorrosion.
    Understanding the mechanisms of biodeterioration / biodegradation of materials.
    Prediction of the service life in a given environment.
    Means to fight against wear and/or corrosion.

Contents - Program

 I.        The phenomenological laws of friction and their manifestations. The different types of friction: sliding, rolling, viscous and aerodynamic friction. Applications: Friction at the heart of technology and biotechnology.

 II.        Wear: the different types of wear and their characterization, the parameters influencing the rate of wear. Quantification of wear: Archard's law. Stribeck's curve.

III.        Expertise of metal parts subjected to wear (helicopter turbine bearing, dental implants).

IV.        The costs of corrosion. Notions of aqueous corrosion of metallic materials: thermodynamic and kinetic aspects, introduction to galvanic series.

 V.        The different types of corrosion: generalized corrosion, galvanic corrosion, crevice corrosion, pitting, intergranular corrosion, selective corrosion, erosion-cavitation corrosion, stress corrosion (case of cracking of prostheses in vivo), microbiological corrosion.

VI.        Means of corrosion control

VII.       Synergistic friction/corrosion effects: tribocorrosion. Application to biodeterioration/biodeterioration of medical devices.

Mode of Evaluation:

Evaluation includes:

    A final written test of two hours covering all the aspects covered
    A project in pairs to be carried out during the whole period of the module and which may include experimental aspects on tribology and corrosion carried out in the laboratory. Report and oral presentation at the end of the module

References - working documents Copies and documents distributed during the module & collection of course slides.

The laws of physical chemistry to materials subjected to an aggressive environment

The laws studied for a better control of the (bio)degradation of metallic materials