Evaluation of cavitation erosion resistance of arc-sprayed Fe-based amorphous/nanocrystalline coatings in NaCl solution

The cavitation erosion behavior of Fe-based amorphous/nanocrystalline coatings has been investigated in specimens prepared by arc spraying process. The cavitation erosion test was performed in a vibratory cavitation apparatus using 3.5 wt% NaCl solution. The results showed that the FeNiCrBSiNbW coating with an amorphous/nanocrystalline structure exhibited higher cavitation erosion resistance compared to the 316L coating in 3.5 wt% NaCl solution. The spray formed defects such as pores, micro-cracks, intersplat regions and oxides in the FeNiCrBSiNbW coating had a negative effect on the cavitation erosion and corrosion behavior. The cavitation erosion failure of the FeNiCrBSiNbW coating was attributed to a brittle fracture mode. The primary cavitation erosion mechanism involved erosion of the intersplats regions, formation of pitting corrosion products and brittle detachment of sprayed layers. Keywords: Cavitation, Coating, Amorphous/nanocrystalline, Fe-base