Optimization of the Process Parameters of Atmospheric Plasma Spraying Cobalt Ferrite Coatings by Orthogonal Experimental Design

In this research, CoFe 2 O 4 coatings have been successfully deposited using atmospheric plasma spraying technique. Orthogonal experiments were designed to systematically investigate the effects of spraying power, distance, and main gas flow on the mechanical properties and microstructure of CoFe 2 O 4 coatings. The results show that the main gas flow has the greatest effect on the microstructure and properties of the coatings among these three factors, followed by spraying distance and spraying power. Comprehensively compared with the porosity, thickness, hardness, and bonding strength of CoFe 2 O 4 coatings, the optimal parameters of sprayed coatings are obtained. In addition, we examined and investigated the hysteresis curves of the coating at room temperature for various spraying distances. The magnetic domain structure of two typical samples was observed. The relationships between magnetic domain structure and crystal orientation, saturation magnetization, and magnetization rate were also discussed. The porosity, thickness, micro-hardness, and bonding strength of the optimal coating are 5.0%, 103 μm, 420.5 HV, and 34.61 MPa and when the spraying distance is 80 mm, the spraying power is 20 kW, and the main gas flow is 30 L min −1 .