Cavitation erosion has been studied for over one hundred years, but its mechanism is still uncertain. It has been found in this research that the existence of micro particles is an important factor to induce cavitation erosion. Experiments in rotating disk equipment were performed, and there is no obvious damage on sample after 5 minutes test in deionzed water, while the one tested in deionzed water with 500nm particles is eroded. Wear debris analysis technique was applied to study the particulates formed in the experiments, and results showed that many debris several micro-meters in size were yielded, which agreed with the scale of the cavitation pits on the sample. It was demonstrated that the mechanical action induces the cavitation erosion.
