Structural and Magnetic Properties of Fe60–xNix(ZnO)40 Nanocomposites Produced by Mechanical Milling and Coated by Thermal Spraying on a Steel Substrate

Abstract

This work aims to study the effect of mechanical milling of Fe, ZnO, and Ni elemental powders and thermal spraying processes on chemical composition, structural properties, and magnetic behavior of the Fe60–xNix(ZnO)40 coatings. As the first step, the FeNi/ZnO composite was synthesized by mechanical alloying process, and afterward, the milled powder was coated by a thermal spraying technique on a steel substrate. Obtained samples were characterized by the methods of X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), atomic force microscopy (AFM), and with help of vibrating sample magnetometer (VSM). After mechanical milling, the crystallite size of the powder decreased from 18 to 10 nm, while the lattice strain increased from 0.31 to 0.59%, and a new solid solution FeNi formed after 20 h of milling due to diffusion of nickel into the iron lattice. After the thermal spraying process, different phases appeared in a surface coating such as ZnFe2O4, NiFe2O4, and FeNi. The magnetic and structural properties of the coated powders are influenced by the change in chemical composition. Thus, the increase of Ni concentration improved the soft magnetic performance of the coating significantly. The highest saturation magnetization was determined in Fe40Ni20(ZnO)40 sprayed powder. However, the smallest coercivity appeared in Fe50Ni10(ZnO)40 sprayed powder.