Influence Mechanism of (NH4)2SO4 on the Composition and Structure of Fe-Co Alloys

Abstract

Fe-Co alloys have the advantages of high saturation magnetization and high magnetic elongation. They are used in electromagnet pole heads, earphone vibration films, magnetostriction transducers, and so on. At present, few papers have been published on the co-deposition process of Fe-Co alloys. In the present work, smooth dense Fe-Co films of 10 μm were successfully prepared in an economical, green, sulfate solution system via electrodeposition. The cathodic polarization curves were measured separately under different conditions, and the electrochemical analyses showed that the increase in the main salt concentration is beneficial for obtaining higher deposition rates. An increase in temperature can increase the current density of electrochemical reduction of Fe2+, and 50 °C is a suitable temperature at which to prepare the Fe-deposited layer with a flat surface. The increase in Co2+ concentration can favor the co-electrodeposition process of Fe-Co alloys. Secondly, the EDS results showed that the mass fraction of Co in the films increased linearly with the increase in Co2+ concentration in the solution. The mass fraction of Co in the films gradually increased with the increase in current density. The mass fraction of Co in the films gradually decreased with the increase in (NH4)2SO4 concentration. In addition, the XRD showed that the grain size of the Fe-Co alloy films was closely related to the concentration of (NH4)2SO4 in the electrolyte, and the smallest crystallite size of the Fe-Co alloy film was 17 nm. SEM showed that (NH4)2SO4 can significantly affect the surface morphology of the films, in which the cracks are obviously removed.