Definition - What does Breakdown Potential mean?
Breakdown potential is defined as the surface potential at which the surface's passive film breaks down. This leads to active electrochemical reaction, causing corrosion or repassivation of the surface in certain conditions.
This is very important in corrosion research and design of corrosion protection, as it is related to the techniques of sustaining passive films for inhibiting corrosion of metallic surfaces.
Corrosionpedia explains Breakdown Potential
Material surfaces, particularly metals, tend to corrode in the presence of an electrolyte. However, corrosion may suddenly slow down or stop completely due to the formation of a thin coating on the surface called the passivating film. If the potential across this film exceeds a certain value, the film may break apart and corrosion may become active again, or the film may form once again, thus protecting the surface.
This potential is called breakdown potential. This process occurs in many metals, including ferrous metals such as stainless steel in electrolytes such as chlorides under industrial or atmospheric conditions.
Sustainability of passive film depends on:
- Surface roughness
- Electrolyte concentration