Cavitation-resistant NiTi coatings produced by low-pressure plasma spraying (LPPS)

Cavitation is a severe wear mechanism in technical applications where parts are in contact with rapidly flowing liquids. Examples are turbine blades in hydropower plants or pump components. Coating exposed surfaces with wear-resistant materials is an effective measure for extending lifetime in the case of cavitation attack. NiTi is an attractive material for such coatings considering its clearly pronounced damping behavior based on its pseudoelastic properties. A promising processing route for coating net-shaped components with NiTi is low-pressure plasma spraying (LPPS). In the present work, NiTi layers were produced by LPPS, starting from pre-alloyed NiTi powder. Cavitation resistance was investigated in relation to LPPS parameters, layer thickness and specific surface treatment. Increased cavitation resistance was demonstrated compared to UTP 730, an established cavitation protection material. The study was accompanied by comprehensive characterization of microstructure and phase transformation behavior of the NiTi coatings.