Corrosion and Cavitation Erosion Behaviors of Two Marine Propeller Materials in Clean and Sulfide-Polluted 3.5% NaCl Solutions

Abstract

The corrosion and cavitation erosion behaviors of two main materials for ship propellers, i.e., nickel–aluminum bronze (NAB) and manganese–nickel–aluminum bronze (MAB) were investigated in a clean and sulfide-polluted 3.5% NaCl solutions. The presence of sulfide increased the corrosion damage of both NAB and MAB by rendering the corrosion product film thicker, more porous and less protective. For MAB, the formation of Fe oxides/sulfides within the corrosion product film may reduce the film compactness and responsible for the lower corrosion resistance, compared with NAB. The presence of sulfide caused the occurrence of more severe corrosion on the surface and therefore further enhanced the cavitation erosion damage. Compared with the result in the clean solution, the cavitation–erosion mass loss rate was raised by a factor of about 11.88% for MAB, and 58.6% for NAB. For NAB, the mechanical erosion dominated the damage in the clean solution, while the cavitation erosion synergy made a significant contribution to the overall damage in the sulfide-polluted solution. For MAB, it was the mechanical damage that contributed mainly to the cavitation erosion damage in both solutions. The exfoliation of large-sized κ phase and the cleavage rupture of β phases resulted in lower cavitation erosion resistance of MAB, compared with NAB.