Hot Vapor Bubble Prints on Carbon Steel

To study the effects of bubbles (or cavities) collapse on a solid surface, a rotating disk device was used here to create bubbles (or bubbles) in water. In the apparatus, these bubbles are led to collapse on the surface of carbon steel (commonly used in structures and machine impellers), and so related to higher costs for the hydraulic machines industry when damaged by such phenomenon, for example. After that, the specimens are observed with the aid of a scanning electronic microscope, where the damages on the specimens are analyzed showing pits and approximate circular areas on their surfaces. An explanation is presented here, based on collapse simulations (for qualitative purposes) and their result using images of the specimens after the collapses to visualize the damages caused by prints on their surface. The pits are certainly made by liquid micro-jet impingement while the areas, showing some aspects of burning, are credited to the high temperature impaction of the bubble contents in the final stages of its collapse.