The conclusions obtained from this study concerning the thermal sprayed materials are as follows. 1) The slurry erosion rates correlate well with both Vickers hardness and a ratio of ceramic particles per area. The erosion rates are almost constant and minimum with the ratio exceeding approximately 25 % and Hv900 in experimental conditions of this study. 2) The cavitation erosion rates correlate with the ratio of pores. The coating layers with a lower ratio of pores are more resistant to cavitation erosion. 3) Regarding the arc spraying, we found that an appropriate heat treatment after the arc spraying was highly effective to improve slurry erosion resistance. 4) Regarding the HVOF and HVAF spraying, we found that the developed coatings have more excellent resistance to slurry and cavitation erosion than the coating currently applied. 5) We have devised an equation for predicting the amount of volume loss by slurry erosion, in which the most important erosion factors were taken into consideration, such as impingement angle, velocity, frequency and distribution of impingement particles. We have presented our study on countermeasures against erosion for pump impellers in the Wanjiazhai plant. We have been acquiring beneficial findings through our investigations and study on erosion of thermal sprayed materials using the Yellow River sand. We have been continuously studying in order to develop surface treatment methods providing higher resistance to slurry and cavitation erosion and improve highly accurate prediction techniques of volume loss by slurry erosion.
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