Cavitation erosion is a major damage phenomenon in hydraulic turbine components that is caused by the bubble collapse. Protective coatings are widely applied as a form of surface modification to resist cavitation erosion. In this work, the WC and Cr3C2 cermet coatings were prepared by using HVOF, and their resistances to cavitation erosion in deionized water and 3.5 wt.% NaCl solution were evaluated. The corrosion behavior was investigated by potentiodynamic polarization in 3.5 wt.% NaCl solution, to examine the damaged surface morphologies and the corrosion products. Results indicated that higher hardness and fracture toughness, and lower porosity could enhance cavitation erosion resistance of the coatings in deionized water. In 3.5 wt.% NaCl solution, the cobalt matrix phase of the WC-12Co coating was dissolved in the corrosive solution, which accentuated the cavitation erosion damage. On the contrary, the oxidation product formed on the WC-10Co-4Cr and Cr3C2-NiCr coatings surface in 3.5 wt.% NaCl solution could mitigate delamination, seal surface pores, and protect from cavitation erosion damage. The WC-10Co-4Cr coating with higher hardness, higher toughness, and lower porosity, which exhibited the ability to form surface oxides in the corrosive solution, showed the best cavitation erosion resistance in both deionized water and 3.5 wt.% NaCl solution.

中文翻译：

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HVOF喷涂WC-10Co-4Cr、WC-12Co和Cr3C2-NiCr涂层的抗气蚀性能和腐蚀行为的性能分析

汽蚀是水轮机部件中由气泡破裂引起的主要损坏现象。保护涂层作为一种表面改性形式被广泛应用，以抵抗气蚀。在这项工作中，使用 HVOF 制备了 WC 和 Cr3C2 金属陶瓷涂层，并评估了它们在去离子水和 3.5 wt.% NaCl 溶液中的抗空蚀性。通过在 3.5 wt.% NaCl 溶液中的动电位极化研究腐蚀行为，以检查损坏的表面形态和腐蚀产物。结果表明，较高的硬度和断裂韧性以及较低的孔隙率可以提高涂层在去离子水中的抗空蚀性。在 3.5 wt.% NaCl 溶液中，WC-12Co 涂层的钴基体相溶解在腐蚀性溶液中，从而加剧了空蚀破坏。相反，WC-10Co-4Cr 和 Cr3C2-NiCr 涂层表面在 3.5 wt.% NaCl 溶液中形成的氧化产物可以减轻分层，密封表面孔隙，防止气蚀损坏。WC-10Co-4Cr 涂层具有更高的硬度、更高的韧性和更低的孔隙率，在腐蚀性溶液中表现出形成表面氧化物的能力，在去离子水和 3.5 wt.% NaCl 溶液中均表现出最佳的抗空蚀性。