Explanation

The phenomenon of surface damage caused by the high impact pressure generated by the collapse of bubbles when a solid moves relative to a liquid. It is also called cavitation corrosion. Bubbles originate from the escape of dissolved gases or the evaporation of liquids when their continuity is disrupted. The typical cavitation failure surface is a large number of spherical pits or honeycomb pits with different diameters. cavitation is the damage caused by mechanical factors, and chemical action will accelerate cavitation damage. The development process of cavitation damage with time can be divided into three stages, namely incubation period, maximum cavitation rate period and stable cavitation rate period. The latter is often the main basis for estimating the ability of materials to resist cavitation. The factors affecting the damage degree of cavitation include the relative velocity of liquid and solid surface, ambient temperature, etc. The cavitation resistance of materials is related to their microstructure and mechanical properties. The practical experience shows that the product of the ultimate resilience of metallic materials (the square of tensile strength divided by twice the elastic modulus) and Brinell hardness can be used as a reference criterion for their cavitation resistance. cavitation damage generally occurs in hydraulic machinery, such as valves, heat exchanger pipes, venturi tubes, water cooled diesel engine cylinder liner walls, pump impellers, ship propellers, turbine blades, reservoir spillway and other large-scale facilities and devices.

Classification