| Abstract: |
Cavitation due to droplet erosion is the major service failure of hydraulic equipment operating in marine environment. Wear and functionality loss of marine structures, such naval propellers made of Nickel Aluminium Bronze alloys, are critical to the efficiency of the engine. Redesign and enhancement of the cavitation erosion resistance of structural alloys, following High Velocity Air Fuel (HVAF) spraying of metal feedstock powders, has been here investigated. Compared to his pioneer HVOF predecessors, the newly-developed supersonic HVAF-M3 system demonstrated significantly reduced both oxidation of metal feedstock materials and coating porosity, which resulted in increase in erosion wear and corrosion resistance of Fe-based coatings. Several noble chemistries including 316L, Fe-rich and Co-rich feedstock materials were supersonically sprayed onto low carbon structural steel, and resulting coating properties enhanced through improvements in feedstock performances and process parameters optimization. Coatings microstructure, microhardness (ASTM E384), adhesion strength (ASTM C633), erosion resistance (ASTM G76), corrosion resistance (ASTM G61, ASTM G150) and cavitation-erosion properties (ASTM G32) were investigated and referred to the bulk material constitutive of a naval propeller. A particular interest was given while combining cavitation erosion and galvanic corrosion in order to mimic the component service life.
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