DC electrodeposition of permanent magnets has been studied using parallel electrodes in aqueous solutions of Sm, Co and glycine. It has been shown that reproducible metallic SmCo alloy electrodeposits of high Sm content sufficient to achieve the intermetallic compounds, SmCo5 and Sm2Co17, have been obtained. These alloys after appropriate heat treatment can provide inexpensive nano- and micron-size as well as electroform materials with high performance permanent magnetic properties. A temperature of 60oC is optimum for producing deposits of at least 32 at % Sm or higher. Some desirable properties can be obtained by the use of certain specific supporting electrolytes. Magnetic hysteresis loops of SmCo deposits at both 25 and 60oC show that as Sm content increases deposits are transformed from anisotropic to isotropic magnetics. Magnetic properties of electrodeposits are comparable to sputtered deposits before heat treatment.
Electrodeposition of SmCo alloys from an aqueous solutions has been studied at various current densities, temperatures and bath compositions. Magnetic properties, such as both parallel and perpendicular coercivities, and magnetic saturation, have been measured. Higher bath temperatures lead to metallic deposits at higher current densities resulting in larger deposit Sm content. 33 at% Sm have been obtained at 500 mA/cm2 from bath temperatures of 60oC. The absence of the conducting salt (NH4 sulfamate) leads to higher deposit Sm content. XRD of these deposits shows the presence of Sm2Co17 (200) and SmCo5 (201) phases. Current efficiencies were below 20%. Magnetic saturation of SmCo electrodeposits were close to those obtained by sputtering. Heat treatment of the deposits should increase the perpendicular coercivities to the 2-10 kOe range.
Pulse current electrodeposition of Sm-Co alloys from aqueous solutions has been studied at various current densities (PCD), solution temperatures, frequency (ν), Ton and duty cycles (γ). A deposit content of 20 at %Sm was obtained at 25oC, higher than at 60oC in contrast to DC from bath of 1M Sm sulfamate, 0.05M Co sulfate, 0.15M glycine at pH6. This composition is sufficient to obtain the high performance permanent magnet intermetallics, Sm2Co17 (10.5 at %) and SmCo5 (16.7 at %), by appropriate heat treatment. Increased PCD, Ton, g and decreased solution temperature or frequency increased Sm deposit content and decreased current efficiency (CE). Magnetic saturation(Ms) decreased linearly with increased Sm deposit content as DC and sputtered films. Increased Sm content resulted in significant decrease in Hc⊥ but Hc|| varied little.
Aqueous electrodeposition of Sm-Co thin film magnetic alloys has been investigated with Hull cell and parallel electrodes using DC and pulse current (PC) methods. The basic solution consisted of 1M Sm sulfamate, 0.05M Co sulfate and 0.15M glycine. Most experiments were conducted at either 25oC or 60oC and various current densities (CD). Sufficient Sm deposit content was achieved to produce the SmCo5 (16.7 at % Sm) and Sm2Co17 (10.5 at % Sm) intermetallics by heat treatment. Parallel experiments confirmed the Hull cell results that increased temperatures and CDs increased Sm content of Sm-Co alloy deposits. Magnetic saturation decreased linearly and coercivity decreased nonlinearly with increased Sm content. Crystalline structures changed to non-crystalline with increase in Sm content. Increased Sm content tended to change magnetic properties from anisotropic to isotropic. For PC on parallel electrodes, higher PCD and lower bath temperatures increased Sm deposit content but decreased current efficiency.
Electrodeposition of Sm-Co magnetic alloys have previously been investigated using Hull cells, DC and pulse methods from aqueous media. The basic electrodeposition solution had been selected as lM samarium sulfamate, 0.05M cobalt sulfate and 0.15M glycine. Solution temperatures ranged from 25oC to 60oC. Increased current density (CD) and temperatures increase deposit Sm content of metallic SmCo alloys. Deposit Sm contents were obtained, with appropriate heat treatment, to produce the intermetallics: SmCo3 (25.0 at %), Sm2Co7, (22.2 at %), SmCo5 (16.7 at %) and Sm2Co17 (10.5 at %). The present work investigates the DC electrodeposition of SmCo alloys in varying aqueous solution constituents, their composition and operating conditions and to consider the coordination chemistry of SmCo ions and aminocarboxylates (glycine). The hydrogen atoms generated at the cathode surface provide the electrons for the sequence of stepwise reduction of Sm and Co in the polymeric glycine complexes to deposit SmCo alloys.
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