An Approach of Cavitation Damage Protection in Propeller by Controlling Coating Microstructure

As the thermal spray coating candidates for anti-cavitation erosive surface modifying layer of the screw propeller in marine vessel, three chemistries: oxide ceramics, carbide cermet and Co based alloy were selected. Test coupons for erosion and other characterization tests were manufactured and coating characteristics such as microscopic surface and cross-section structures were evaluated by using scanning electron microscope and Optical digital-microscope.

Regarding the development of manufacturing techniques for anti-erosive propeller, the model propeller for characteristic verification was made in the same material as the actual propeller and the accelerated test for cavitation erosion was carried out in a cavitation tank. As a result, sprayed coating proves to be effective against cavitation erosion.

The control items of thermal spray coating production techniques for an actual screw propeller, such as thermal spraying condition, the motion trajectory of spray gun and sprayability for the three-dimensional concave and convex of screw propeller, were discussed.