Optimization of HVOF spraying parameters for enhanced Fe-based amorphous coatings: A taguchi approach

Abstract

In this work, Fe57Cr15Mo8P10C7B3 amorphous coatings (ACs) were fabricated on 316L stainless steel (316L SS) substrate using high-velocity oxygen-fuel (HVOF) spraying technique. The Taguchi's method guided the design of L16 (43) orthogonal experiments to optimize the process parameters, including spraying distance, oxygen flow rate, and kerosene flow rate. Through statistical analyses, including signal-to-noise ratio analysis, analysis of variance (ANOVA), and response surface methodology (RSM), empirical relationships for evaluating the influence of these parameters on coating quality were established, with porosity as the primary metric. Our findings indicate a pronounced sensitivity of the porosity of the ACs to spraying conditions, in which oxygen flow rate has the most significant effect on the porosity of the ACs, while kerosene flow rate has the smallest impact. Meanwhile, it is predicted that a minimum coating porosity of 0.75 % can be achieved under the optimal deposition conditions of the spraying distance of 330 mm, the kerosene flow rate of 6.0 GPH, and an oxygen flow rate of 1900 SCF. Experimental validation confirmed these conditions, yielding coatings with superior coating quality and performance with a minimum coating porosity of 0.68 %, a microhardness of 826 ± 65 HV0.1, improved corrosion resistance in 3.5 wt% NaCl solution with a high self-corrosion potential of −0.37 V, a low self-corrosion current density of 1.08 × 10−6 A/cm2, and a low passivation current density of 1.16 × 10−5 A/cm2, and enhanced wear performance with a wear volume loss of only 4.00 × 10−5 mm3 N−1 m−1 and a friction coefficient of as low as 0.42 ± 0.022. The present study confirms the reliability of Taguchi's method in determining optimal HVOF processing parameters, evidenced by the consistency between theoretical predictions and experimental results.