電解銅粉の析出挙動および銅粉の形態に及ぼすハロゲン化物イオンの影響

抄録

To investigate the effect of halide ions on the electrodeposition behavior and morphology of copper powder, the polarization curves were measured and constant current electrolysis of 300 A·m⁻² and 500 A·m⁻² was conducted in an electrolytic solution of 0.079 mol·dm⁻³ of Cu²⁺ and 0.5 mol·dm⁻³ of free H₂SO₄ at 293 K and 303 K without stirring. In the deposition of copper powder, Cl⁻ had a promoting effect on the deposition of copper powder, while Br⁻ and I⁻ had a suppressing effect. The current efficiency for Cu deposition increased with the addition of Cl⁻ and decreased with Br⁻. The addition of Cl⁻ reduced the average particle size of the copper powder and grown dendrite-shaped branches and trunks, resulting in a lower tap density. On the other hand, when Br⁻ was added, the average particle size and crystallite size of the copper powder became smaller, and the tap density also became smaller. With increasing Cl⁻ concentration in solution, the current efficiency for Cu deposition increased, that is, copper deposition was promoted even in the diffusion rate-determining region of Cu²⁺ ions, showing that the deposition of copper powder was affected by the charge transfer process for Cu deposition. The change in morphology of Cu powder with halide ions is attributed to change of the charge transfer process. The deposition of Cu powder seems to proceed under a mixed rate-determining process of the diffusion of Cu²⁺ ions and charge transfer.

Fig. 7　SEM images of copper powders deposited in the electrolyte containing various amounts of Cl⁻ ions. (a) Cl⁻ 0 mg·dm⁻³, (b) Cl⁻ 10 mg·dm⁻³, (c) Cl⁻ 100 mg·dm⁻³, (d) Cl⁻ 200 mg·dm⁻³