The coupling effect of cavitation-erosion and corrosion for HVOF sprayed Cu-based medium-entropy alloy coating in 3.5 wt.% NaCl solution

Ship propellers suffered from serious coupling damage of cavitation-erosion (CE) and corrosion when operated with high-speed in the marine environment. To improve the CEcorrosion resistance of the Ni-Al bronze (NAB) propeller alloy, a novel Cu-based mediumentropy alloy coating (Cu55Al20Ni12Ti8Si5, at.%) was prepared by high-velocity oxygen-fuel spraying technology in this study. The characteristics and CE behavior of coating and NAB were comparatively investigated, then the CE damage mechanism was discussed by analyzing CE damage morphologies. The influence of CE on corrosion behavior and the coupling effect between CE and corrosion were further elucidated by electrochemical corrosion experiments. The results indicated that the as-sprayed coating mainly comprised of BCC solid solution phase and NiTi-rich precipitates, which possessed higher hardness (6.73 +/- 1.23 GPa) and superior resilience (27.0%) than the NAB. The cumulative mass loss rate for the coating after 18 h CE in distilled water and 3.5 wt.% NaCl solution was only 38.7% and 80.6% that for the NAB, revealing the better anti-CE performance of the coating. The preferential CE of the BCC matrix around the NiTi-rich precipitates, fatigue fracture and lamellar spalling were summarized as the main CE damage mechanism for the coating in 3.5 wt.% NaCl solution. CE had a significant influence on corrosion behavior of coating and NAB, which resulted in corrosion performance degradation of both two materials. The CE-corrosion coupling effect led to the remarkable mass loss, and mechanical effect rather than corrosion effect was ascribed to be the dominated factor for the damage of coating and NAB. (c) 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC

Automated summary

This study aims to improve the cavitation-erosion (CE) corrosion resistance of Ni-Al bronze propeller alloy by preparing a novel Cu-based medium-entropy alloy coating. The coating exhibited better anti-CE performance compared to the Ni-Al bronze alloy, with the main CE damage mechanism being corrosion and fatigue damage caused by the NiTi-rich precipitates in the coating.