How does exfoliation corrosion manifest in metals?

Exfoliation corrosion is a specific type of localized corrosion that primarily affects aluminum alloys and occurs in critical applications such as naval vessels. It manifests as a lifting or separation of surface layers or grains of the metal. This lifting occurs due to the formation of corrosion products that create internal pressure within the metal structure. These corrosion products separate the layers, leading to the characteristic appearance of flaking or peeling as the corrosion advances.

The phenomenon is often exacerbated in metals that have a layered structure, where the corrosion penetrates along the grain boundaries, promoting the separation of surface layers. This can compromise the structural integrity of the material over time, especially in environments that are exposed to moisture or seawater. Understanding exfoliation corrosion is crucial for maintenance and prevention strategies, especially in marine applications where metals are constantly exposed to corrosive environments.