attributes crevice corrosion?

Crevice corrosion is a localized form of corrosion usually associated with a stagnant solution on the micro-environmental level. Such stagnant microenvironments tend to occur in spaces such as those between metallic surfaces and the surfaces they are in contact with (e.g., deposits, product residues, gaskets, fastener heads, rivets, lap joints, etc.).

Here are the attributes of crevice corrosion:

1. Localized Corrosion: Crevice corrosion is a type of localized corrosion, which means it occurs in a specific, localized area, rather than across the entire surface of the material.

2. Stagnant Conditions: Crevice corrosion typically occurs in areas where the movement of the corrosive fluid is limited. This could be under deposits on the metal surface, under gaskets, or in crevices.

3. Micro-environment: The corrosion occurs in a micro-environment that is different from the larger environment. This micro-environment is often more aggressive, with a lower pH and higher chloride concentration.

4. Metallic Path: There needs to be a metallic path between the crevice and the bulk environment for the corrosion to occur.

5. Critical Crevice Geometry: The geometry of the crevice plays a crucial role in the initiation and propagation of crevice corrosion. The crevice needs to be tight enough to promote stagnation but wide enough to allow for the ingress of the corrosive solution.

6. Breakdown of Passive Film: Crevice corrosion often occurs in metals that rely on a passive film for protection against corrosion. The corrosive conditions within the crevice can lead to the breakdown of this film, leading to corrosion.

7. Accelerated Attack: Once initiated, crevice corrosion often leads to accelerated attack within the crevice due to the concentration of corrosive species and the development of a highly aggressive microenvironment.