Question

The lifting or flaking of the metal at the surface due to delamination of grain boundaries caused by the pressure of corrosion residual product buildup is called?

1) Corrosion fatigue
2) Stress corrosion cracking
3) Intergranular corrosion
4) Exfoliation corrosion

Answer 1

Exfoliation corrosion is the correct term for the lifting or flaking of the metal at the surface due to the pressure of corrosion product buildup which forces the metal apart along the grain boundaries.

Step-by-step explanation:

The lifting or flaking of the metal at the surface due to delamination of grain boundaries caused by the pressure of corrosion residual product buildup is called exfoliation corrosion. This form of corrosion is often seen in high-strength aluminum alloys and is characterized by layers of the material separating or flaking away from the substrate. It's similar to the concept of rust formation in iron, where iron is oxidized to iron (II) ions by oxygen and then further oxidized with water and oxygen to form hydrated iron (III) oxide, known as rust. This is, however, a more advanced form of corrosion where the layers peel away due to the volume expansion of the oxide products forcing the metal apart along the grain boundaries.