Synergism between corrosion and wear
Examples of corrosion are found in many industrial applications ranging from aeronautical, automotive, naval, and the construction industry over home appliances, water systems, pipelines, and ‘bio’ applications. Corrosion phenomena can be significantly accelerated by the simultaneous occurrence of a mechanical load on the surface: the formation of cracks and surface defects, along with surface strain and stress fields lead to faster diffusion of corrosive ions or the destruction of protective layers (depassivation). Thus there is a need to understand the synergy between wear and corrosion.
An electrochemical cell was implemented in the Basalt-N2 tribometer. This setup allows for a fast and accurate measurement of the frictional behaviour of materials under various environments, whereas it is flexible and versatile in loading range (depending on the selecting cantilevers, load can range from 0.2 mN up to 100 N) and different contact geometries (point, line, area contacts) can be used. In this way both the tribological and electrochemical properties can be monitored and correlated.
- The influence of wear on corrosion mechanisms, and vice versa, can be investigated.
- Mechanical loading and shearing or rupture of the passivating layer accelerate corrosion (seen as sudden drop of the open circuit potential).
- Corrosion processes can change the surface of the material (formation of oxides, hydroxides) and influence its frictional behavior.
- In the majority of cases, the synergism between corrosion and mechanical loading accelerates wear processes but in some cases the synergy may be positive.