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Journal of the Electrochemical Society, Vol.155, No.10, D660-D665, 2008
Aqueous electrodeposition of SmCo alloys - I. Hull cell studies
The Hull cell (HC) is a rapid "economical" method for screening the effects of varying solution composition and operating variables, providing a preliminary parametric study of Sm-Co alloy electrodeposition. HC deposit patterns exhibited three distinct current density (CD) areas: a metallic deposit, a "burnt" deposit, and a nonmetallic oxide/hydroxide deposit. X-ray diffraction spectra indicated the metallic deposits were generally amorphous, essentially free of oxide/hydroxide; the burnt deposits contained varying amounts of Sm-Co, Co hydroxide, and Sm oxide/hydroxide, and the nonmetallic deposits consisted of oxide/hydroxide. Increased temperatures extended CD ranges for metallic deposits (CDmax), resulting in increased Sm content. The CD for electrodeposition of metallic Co from dilute Co solutions increased with increasing temperature; addition of glycine significantly increased CDmax. HC patterns from solutions containing only Sm sulfamate were devoid of metallic deposits. Addition of complexants (glycine) is essential for the electrodeposition of Sm-Co alloys. For pulsed current (PC) electrodeposition, increasing the solution temperatures did not result in increased Sm content as dc, although PCDmax was extended. Decreasing the duty cycle increased PCDmax at 25 degrees C. PC results at 25 degrees C indicate that alloy compositions may be electrodeposited, favorable to subsequent thermal treatments to intermetallic compounds, SmCo5 and Sm2Co17. (C) 2008 The Electrochemical Society.