Influence of HVOF Processing Parameters on the Amorphous Fraction and Properties of FeCrMoBC Coatings

In this study, gas-atomized FeCrMoBC amorphous powder was used as the feedstock, and an orthogonal experimental design was employed to investigate the effects of key high-velocity oxy-fuel (HVOF) spraying parameters, including kerosene flow, oxygen flow, spray distance, and powder feed rate, on the microstructure and properties of the coatings. The results showed that the amorphous fraction increased from 75.03% in the feedstock powder to as high as 96.18% in the HVOF-sprayed coatings, indicating substantial retention and enrichment of the amorphous structure during deposition. Among the investigated conditions, the No. 9 coating, prepared at a kerosene flow of 7.5 GPH, an oxygen flow of 1900 SCFH, a spray distance of 350 mm, and a powder feed rate of 30 g/min, exhibited the most favorable combination of properties, with a microhardness of 838 HV0.1, a wear rate of 2 × 10−5 mm3·N−1·m−1, an amorphous fraction of 96.18%, and a porosity of 1.03%. Higher hardness was generally associated with lower wear rates, while coatings with higher amorphous fractions exhibited lower corrosion current densities. The observed wear morphology was consistent with combined oxidative and abrasive wear. These results establish correlations among HVOF processing parameters, amorphous fraction, coating porosity, and wear and corrosion performance, and provide a practical basis for tailoring Fe-based amorphous coatings with a favorable combination of structural integrity, wear resistance, and corrosion resistance.