Process Selection for the Fabrication of Cavitation Erosion-Resistant Bronze Coatings by Thermal and Kinetic Spraying in Maritime Applications

The present study compares prerequisites for cavitation-resistant bronzes production by different coating techniques, namely cold spraying, HVOF spraying, warm spraying and arc spraying. If optimized to maximum cavitation resistance, the deposited coatings can increase the service life of ship rudders significantly. Furthermore, these methods could enable repair processes for ship propellers. This study is meant to help selecting the right coating technology to achieve best cavitation protection for a given set of requirements. Using high-pressure warm spraying and cold spraying, properties similar to those of cast nickel aluminum bronze are achieved. Also, coatings produced by using HVOF and arc spraying have erosion rates that are only about four, respectively, three times higher as compared to cast nickel aluminum bronze, while by far outperforming bulk shipbuilding steel. Their properties should be sufficient for longer service life, i.e., less docking events for ship rudder repair. Hence, with respect to costs, HVOF and arc spraying could represent a good compromise to reach the specified coating properties needed in application, potentially even for propeller repair.