Optimization of the HOVF Spray Parameters by Taguchi Method for High Corrosion-Resistant Fe-Based Coatings

Taguchi method was used to optimize the parameters of the high velocity oxygen fuel (HVOF) spray process and obtain the high corrosion-resistant Fe-based coatings. Based on the signal-to-noise (S/N) ratio and the analysis of variance, the significance of spray parameters in determining the porosity of the coatings was found to be in the order of spray distance, oxygen flow, and kerosene flow. Thus, the optimal parameters for the porosity of the HVOF sprayed Fe-based coating were determined as 280 mm for the spray distance, 963 scfh for the oxygen flow, and 28 gph for the kerosene flow. The potentiodynamic polarization and EIS tests indicated that the Fe-based coating prepared with the optimal parameters exhibited a higher corrosion potential (E (corr)) of -196.14 mV, a lower corrosion current density (i (corr)) of 0.14 mu A/cm(2), and a higher coating resistance (R (c)) of 2.26 x 10(6) Omega cm(2) than those of the hard chromium coating in 3.5% sodium chloride solution. This superior corrosion resistance could be attributed to the dense structure with low porosity and partially amorphous phases of the Fe-based coatings.