Erosion occurs when a stream of typically finer particles or liquid droplets, travelling at moderate to high speeds, hits a surface. Under normal conditions, a number of hits are required before any loss of material will take place. When particles hit the surface of brittle materials, the loss takes place as a brittle fracture and in the case of ductile materials, it takes place as a combination of chip formation, fatigue, and shear failure.
Erosion caused by particles suspended in a liquid is referred to as slurry erosion and is a common wear phenomenon found in pumps, or it can occur as cavitation erosion, which is caused by imploding water vapour bubbles on the surface of a material, such as pump casings and impellers. Surfaces that are subject to erosion will deteriorate over time, causing weakening, which results in the surface cracking, breaking away, or being pierced.
Particles impacting surfaces can come from multiple directions, meaning that the wear can be present over large surface areas and not just isolated to one place. Regular maintenance of parts can limit part failure or in a worst-case scenario, a total plant shutdown.