Laser surface alloying of a marine propeller bronze using aluminium powder: Part II: Corrosion and erosion–corrosion synergism

Laser surface alloying of MAB (manganese–nickel–aluminium bronze) with Al brought about an increase in both the corrosion resistance and cavitation erosion resistance in 3.5% NaCl solution, with a higher increase in comparison with laser surface melting (LSM). The erosion resistance of the laser surface-alloyed sample in NaCl solution was significantly lower than that in deionized water, indicating that corrosion played an important role in the overall material removal. Under the present experimental conditions, strong erosion–corrosion synergism was present. By employing polarization resistance measurements under quiescent and cavitating conditions, the contributions of erosion-induced corrosion and corrosion-induced erosion were determined. For laser surface-alloyed MAB, most of the synergistic effect was contributed by corrosion-induced erosion. The galvanic effect between the laser-treated and as-received samples was small, this being a favorable factor for justifying the use of laser surface alloying with Al as a feasible method in the local surface treatment of MAB.