Effect of saccharin and thiourea on electrodeposition of cobalt and characteristics of deposits

Abstract

Cobalt electrodeposits have been produced from two types of baths. In the bath containing cobalt sulphate, cobalt chloride and boric acid, saccharin is found effective as a brightener additive. In the bath containing cobalt sulphate, potassium chloride and potassium citrate, thiourea is found to be effective as a brightener additive. Results of solution characteristics such as conductivity of the electrolytes, cathode current efficiency and rate of deposition are compared. The effect of additives on brightness, roughness, orientation of the crystal, grain size and surface morphology of the cobalt deposits are reported. The X-ray diffraction pattern obtained for electrodeposited cobalt showed a polycrystalline nature with hexagonal close packed structure. A smooth uniform and pore free surface was observed under scanning electron microscopy and atomic force microscopy analysis. Potentiodynamic polarisation and electrochemical impedance measurements in sodium chloride solution showed that a higher corrosion resistance was observed for the deposit from the second type of bath containing an additive.

Effect of saccharin addition on formation, wear and corrosion resistance of electrodeposited Ni-Cr coatings

“…This particular Furthermore, the primary reason for the change in corrosion resistance can be attributed to the elimination of defects on the coating surface facilitated by the addition of saccharin. The additives in the coating served as a physical barrier by filling cracks and micron-sized gaps, partially obstructing reactive areas and reducing cathodic reactions [13].…”

“…However, an excess of sulphur led to negative corrosion results. Additionally, the coatings' active area decreased as a result of the addition of saccharin [13].…”

“…In various studies, a range of additives, including saccharin, gelatine, sodium deoxyl sulphate, trimethylamine borane (TMAB), and cetyltrimetylammonium bromide (CTAB), have been examined for their effects. The focus of this study is on the addition of saccharin and its effects on different alloy or composite coatings such as Ni [8,11], Co [12,13], CoNi [10,14], CoPt [15], NiMo [16], ZnNi [17], NiFe [18], NiW [19], NiWP [20] and NiFe/SiC [21]. Tebbakh et al conducted research on Ni-Co alloy coatings on a ruthenium substrate, in which they added saccharin at various concentrations to the electrolytic bath.…”

Proton Sensitive Additive for Cobalt Electrodeposition

“…Therefore, previous researches on cobalt electrodeposition mainly focused on the cobalt structure, shape control, and deposition mechanism for the cobalt film on the plane substrate. [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] In contrast, in patterned areas such as interconnects, the purpose of the study is completely different, and research on the electrodeposition for feature filling using cobalt is insufficient.…”