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Abstract:The arc spraying process was used to prepare Fe-based amorphous/nanocrystalline coating. The cavitation erosion behaviors of FeNiCrBSiNbW coatings with different surface roughness levels were investigated in distilled water. The results showed that FeNiCrBSiNbW coating adhered well to the substrate, and was compact with porosity of less than 2%. With increasing initial surface roughness, the coatings showed an increase in mass loss of cavitation erosion damage. The amount of pre-existing defects on the initial surface of the coatings was found to be a significant factor for the difference in the cavitation erosion behavior. The cavitation erosion damage for the coatings was a brittle erosion mode. The evolution of the cavitation erosion mechanism of the coatings with the increase of the initial surface roughness was micro-cracks, pits, detachment of fragments, craters, cracks, pullout of the un-melted particle, and massive exfoliations.

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Plasma-sprayed Cr 2 O 3 -8 wt-% TiO 2 coatings were deposited on mild steel and sealed by epoxy resin and silicone resin in different processes. The microstructure and corrosion resistance of all coatings were investigated. The results showed that silicone resin sealant can seal the coating well and 91% of interconnected porosity was blocked. The sealant can penetrate into the coating by more than 280 mm. The coating sealed with silicone resin in vacuum conditions had the highest corrosion potential E corr (2375 mV) and lowest corrosion current density i corr (17 mA m 22 ) in electrochemical tests. Correspondingly, the unsealed coating had the lowest E corr and highest i corr . The corrosion resistance of the coatings was in the following order: coating sealed with silicone resin in vacuum.coating sealed with silicone resin in air.coating sealed with epoxy resin in vacuum.coating sealed with epoxy resin in air.unsealed coating.