A Method for Predicting Cavitation Erosion-Corrosion Damage in Simulated Seawater

摘要

The influence of corrosion on cavitation erosion of metallic materials, with emphasis on the behavior of the material surface during the incubation period in a corrosive environment was investigated. As expected, in the case of brass, the duration of the incubation period was reduced in the corrosive environment, but that for pure copper was prolonged. This can be explained by the tensile force caused by the adsorption of ions in the corrosive solution. The relationship between the increment of surface area and testing time during the incubation period, a key to predicting the duration of the incubation period as well as of damage rate thereafter, was moved parallel to the time axis, but maintained the same shape for each material tested independent of the environment. Polarization curves of each material under cavitation were measured and the corrosion rate was found to be accelerated by the solution agitating effect of cavitation. Thus it is confirmed that the duration of the incubation period of cavitation erosion-corrosion for a material can be determined by measurement of the increment of the surface area of the material, and the corrosion rate can be predicted from polarization curves, which can be measured under the condition of cavitation.