Aqueous Electrodeposition of SmCo Alloys: I. Hull Cell Studies

Abstract

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 , 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 . 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 was extended. Decreasing the duty cycle increased at . PC results at indicate that alloy compositions may be electrodeposited, favorable to subsequent thermal treatments to intermetallic compounds, and .