Co-28Mo-8Cr-2Si涂层在去离子水和人工海水中的气蚀性能

Cavitation Erosion Behavior of Co-28Mo-8Cr-2Si Coating in Deionized Water and Artificial Seawater

服役于海洋中的多种零部件往往因腐蚀-气蚀联合作用而严重损坏。文中采用超音速火焰喷涂(HVOF)技术制备了Co-28Mo-8Cr-2Si涂层,使用光学显微镜、X射线衍射仪、显微硬度计等设备分析涂层的组织结构和力学性能,使用电化学工作站考察涂层的腐蚀性能,使用超声波振动气蚀试验机评价了涂层分别在去离子水和人工海水中的气蚀性能,利用扫描电镜(SEM)观察涂层腐蚀和气蚀后的形貌。结果表明:在去离水中,涂层的气蚀机理主要是孔隙周围的扁平粒子大片剥落,气蚀6h后,涂层的累积体积损失高达4.15mm3;在人工海水中,腐蚀产物有效地填充了涂层表面的孔隙,大大降低了扁平粒子剥落情况的发生,气蚀6h后,涂层的累积体积损失仅为1.83mm3。

Many components used in the ocean have been destroyed by the conjoint action of corrosion and cavitation erosion. The Co28Mo8Cr2Si coating was prepared by high velocity oxyfuel spraying （HVOF）. The microstructure and phase composition of assprayed coating was analyzed by optical microscope and Xray diffraction. A Vicker’s hardness tester was performed to measure the microhardness of the coating. The corrosion behavior and cavitation erosion behavior of the coating was evaluated by potentiodynamic polarization test and a vibrationinduced laboratory cavitation tester, respectively. The morphology of the coating after cavitation erosion test and corrosion test was observed by scanning electron microscope （SEM）. It has been found that the dominant cavitationerosion mechanism of the coating in deionized water is the detachment of flat particles around the pores. After cavitation erosion test for 6 h, the cumulative volume loss of this coating is up to 4.15 mm3. In artificial seawater, the surface pores are effectively filled with corrosion products, which significantly reduce the occurrence probability of the detachment of flat particles. After cavitation erosion test for 6 h, the cumulative volume loss of the coating is only 1.83 mm3.