Abstract:The cavitation damage of the overflow components of the hydraulic turbines causes the removing of the equipment materials, thus damage unit structure and degrades the safety of units. Thermal sprayed coatings are effective method against cavitation damage. This paper intends to improve the cavitation corrosion resistance of the coating by reducing the porosity of the coatings. Micro-nano composite WC coatings were fabricated by air-combusted high-velocity oxygen fuel spray (AC-HVAF). Static vibration cavitation test and high-speed fluid cavitation test were respectively used to characterize the cavitation resistance performance of the coatings. The results showed that the micro-nano WC composite coatings by AC-HVAF exhibited a homogeneous and dense microstructure with porosity of 0.2%. Compared with the same coatings deposited by HVOF, higher resistance to cavitation is examined during vibration cavitation test and high speed fluid cavitation test for micro-nano WC composite coatings prepared by AC-HVAF. After 5.5 years operation, the coatings remained intact. The micronano composite WC coatings deposited by AC-HVAF can effectively improve the anti-cavitation ability of hydropower equipment and the safety of the unit.