Influence of the high-velocity oxygen-fuel spray parameters on the porosity and corrosion resistance of iron-based amorphous coatings

In this paper, the high-velocity oxygen-fuel (HVOF) spraying technology was used to prepare the iron-based amorphous coatings onto the substrate of 45 steel. Three parameters of spray distance, oxygen flow and kerosene flow were optimized by the Taguchi method, with the porosity of the coatings as object. The statistical tools including orthogonal experimental design, signal-to-noise ratio and analysis of variance were used to optimize the spray parameters. The results indicated that the kerosene flow showed the highest effect on the porosity of the coatings, while the oxygen flow exhibited the least influence. It was found that the coating with lowest porosity was deposited under the spray distance of 380 mm, the oxygen flow of 1840 scfh, and the kerosene flow of 6.8 gph. The potentiodynamic polarization and electrochemical impendence spectroscopy (EIS) results manifested that the iron-based amorphous coating prepared with proper spray parameters exhibited superior corrosion resistance to the hard chromium coating. Besides, the coating with lower porosity exhibited better corrosion resistance than the coating with higher porosity.