Thermally sprayed cermet coatings are adequate solutions to improve cavitation and wear resistance of hydraulic turbines made of stainless steel (SS), especially in rivers with a high sediment load, such as the Madeira River in Brazil. However, some cermets are easily dissolved in river water, leading to premature failure of the coating and costly maintenance. Moreover, galvanic corrosion induced by coupling the cermet to a SS can accelerate the coating dissolution. Therefore, the corrosion resistance of six cermets (WC-12Co, WC-10Ni, WC-10Co-4Cr, Cr3C2-25NiCr, Cr3C2-10NiCr and Cr3C2-10Ni) and the galvanic corrosion resistance of these materials coupled to CA6NM SS were evaluated in a solution that simulated Madeira River water. WC-12Co and WC-10Ni cermets exhibited the highest corrosion rates, 0.077 and 0.068 mm/year, respectively, whereas the Cr content in the WC-10Co-4Cr (0.017 mm/year) and Cr3C2-based coatings (0.005 to 0.007 mm/year) led them to corrode at slower rates. Moreover, the WC-10Co-4Cr and Cr3C2-based cermets exhibited negligible galvanic corrosion current when coupled to the CA6NM SS, making them good options to coat hydraulic turbines. In contrast, WC-12Co and WC-10Ni coatings underwent a more severe galvanic corrosion process, which would drastically reduce the lifespan of these materials as hydraulic turbine coatings.

中文翻译：

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WC 和 Cr3C2 金属陶瓷涂层在马德拉河水中的腐蚀行为和耐电偶腐蚀性能


热喷涂金属陶瓷涂层是改善不锈钢 (SS) 水轮机耐气蚀和耐磨性的适当解决方案，特别是在沉积物含量高的河流中，例如巴西的马德拉河。然而，一些金属陶瓷很容易溶解在河水中，导致涂层过早失效并导致昂贵的维护费用。此外，通过将金属陶瓷与SS耦合引起的电偶腐蚀可以加速涂层溶解。因此，评估了六种金属陶瓷（WC-12Co、WC-10Ni、WC-10Co-4Cr、Cr3C2-25NiCr、Cr3C2-10NiCr 和 Cr3C2-10Ni）的耐腐蚀性以及这些材料与 CA6NM SS 耦合的耐电偶腐蚀性能。模拟马德拉河水的解决方案。 WC-12Co 和 WC-10Ni 金属陶瓷表现出最高的腐蚀速率，分别为 0.077 和 0.068 毫米/年，而 WC-10Co-4Cr 中的 Cr 含量（0.017 毫米/年）和 Cr3C2 基涂层（0.005 至 0.007 毫米） /年）导致它们以较慢的速度腐蚀。此外，当与 CA6NM SS 耦合时，WC-10Co-4Cr 和 Cr3C2 基金属陶瓷表现出可忽略不计的电偶腐蚀电流，使其成为涂覆水轮机的良好选择。相比之下，WC-12Co和WC-10Ni涂层经历了更严重的电偶腐蚀过程，这将大大缩短这些材料作为水轮机涂层的使用寿命。