Development of Advanced Anti-cavitation Erosion Performances in Thermally-sprayed Co-based Alloy Coatings

Anti-cavitation erosion performances of thermally sprayed cobalt-based alloy coatings were compared with that of aluminum bronze castings, which have been utilized as s substrate for propeller in marine vessel because of its formability, endurance against seawater, and the cavitation erosion resistance. Cobalt-based alloy coatings are fabricated by using three thermal spray processes: atmospheric plasma spray, low-pressure plasma spray and high velocity oxygen fuel flame spray. The ultrasonic vibration type cavitation erosion testing apparatus were employed for the cavitation erosion rate measurement. The cavitation erosion performances determined by the specific volume loss rate of low-pressure plasma-sprayed cobalt-based alloy and HVOF sprayed cobalt-based alloy coatings were improved five times and twice compared with that of aluminum bronze castings, respectively. The anti-cavitation erosion performance of atmospheric plasma sprayed cobalt-based alloy coating did not reach the level of aluminum bronze castings.