Electroplating Dysprosium from IL-Based Solutions: A Promising Electrochemical Step to Produce Stronger High Performance Nd(Dy)-Fe-B Sintered Magnets

An electrodeposition replacement to the commonly used physical vapor deposition methods used in enhancing the coercivity of Nd-Fe-B sintered magnets has been proposed. Dysprosium was galvanostatically electroplated on Nd-Fe-B sintered magnets that were previously electrochemically coated with copper. Electroplated dysprosium films were characterized by X-ray photoelectron spectroscopy, depth profiling, scanning electron micrographs, and energy dispersive X-ray spectroscopy. XPS analysis after argon ion sputtering indicates that minor impurities are only superficial as their atomic fractions in the sample nearly disappear with increasing etching time. The electrochemistry of synthesized dysprosium bis(trifluromethylsulfonyl) imide dissolved in the air- and water-stable ionic liquid 1-butyl-3-methylpyrrolidinium bis(trifluoromethylsuflonyl) imide was studied by cyclic voltammetry. Electroplating of metallic dysprosium was followed by a heat-treatment above the melting temperature of the Nd-rich phases of the sintered magnet base body whose magnetic characterization was performed in a hysteresis loop tracer for hard magnetic materials. (C) The Author(s) 2015. Published by ECS.