Effect of Spraying Power on Microstructure, Corrosion and Wear Resistance of Fe-Based Amorphous Coatings

The porosity and oxide content in high-velocity oxy-fuel (HVOF)-sprayed amorphous coatings usually show opposite dependence on spraying parameters (e.g., the oxygen/fuel ratio, spraying power, feed rate and particle size of the feedstock powders), which negatively affects the performance of the coatings. In this work, Fe63Cr8Mo3.5Ni5P10B4C4Si2.5 (at.%) amorphous coatings were produced by HVOF spraying process with varying spraying powers. As the spraying power increases, the resultant coating shows a low constant content and more uniform distribution of oxides while the porosity is decreased. The developed microstructure is attributed to the improved splat deformation and oxidation-resistant alloy composition of feedstock powders. Consequently, the coating exhibits better corrosion and wear resistance with the increase of spraying power. The increased corrosion resistance is attributed to the formation of a more protective passive film with higher thickness and pitting resistance. The enhanced wear resistance mainly depends on the higher stability of the antiwear oxide tribofilm and stronger resistance to lamellar spallation. The findings thus provide a guidance for the preparation of high quality HVOF-sprayed amorphous coatings.