Optimizing Parameters of Arc-Sprayed Fe-Based Coatings Using the Response Surface Methodology

Arc-sprayed Fe-based coatings can provide a cheaper and more effective way of protecting cutting tools made of 65Mn steel against abrasive wear. Due to contact with hard and rocky soils, rotary tiller blades face extreme surface wear that reduces their service life. In this study, a new Fe-based coating was prepared on 65Mn steel substrates using arc spraying process. The influence of the process variables (spray distance, voltage, and current) on the microhardness and porosity was studied based on the response surface methodology (RSM). By maximizing microhardness and minimizing porosity, the optimum spraying parameters were voltage of 35 V, current of 150 A, and spray distance of 270 mm. Based on the process optimization, the desired coating was obtained with a microhardness and porosity of 783.62 ± 14.77 HV 0.1 and 1.51 ± 0.49%, respectively. Validation tests of the coatings with the optimum conditions agree with the values predicted by the model. The microstructure, tensile bonding strength and wear tests of the optimized coatings were characterized. The Fe-based coating had a bonding strength of 40.8 ± 1.4 MPa. The wear rate of the coating was 12.26 × 10 −6 mm 3 /Nm, which was about 2.4 times lower than that of the 65Mn steel substrate.