What process is described by the repetitive creation and destruction of surface films on metals?

The repetitive creation and destruction of surface films on metals refers to erosion corrosion. This process occurs when a protective layer, such as an oxide film, is continuously disrupted due to the mechanical action of fluids flowing over the metal surface. As the fluid moves, it can remove or break down this protective layer, exposing the underlying metal to the corrosive environment, leading to accelerated corrosion.

Erosion corrosion often occurs in conditions with high flow velocities or turbulent flow, where the mechanical forces acting on the metal surface are significant enough to overcome the protective film's stability. This leads to localized wear and tear, resulting in increased metal loss over time.

Understanding this process is vital for power engineers, as it can impact the integrity and longevity of various metal components used in systems dealing with liquid or gaseous flow, such as pipes, pumps, and heat exchangers. Recognizing the conditions that lead to erosion corrosion allows for better design and material selection to minimize its effects.