Electrodeposition at rotating cathodes from acidified copper sulphate solution

Abstract

The variation of the relationship between polarisation and current density at a rotating copper cathode in an electrolyte of copper sulphate and sulphuric acid has been observed under conditions and concentrations similar to those employed in the plating industry, and during the formation of thick deposits. The effect of the following parameters was studied: time of electrolysis, agitation, temperature and composition of electrolyte, and the consequent effects upon the structure of the resulting deposits were noted. The possible effects of the co‐deposition of hydrogen at the cathode is discussed in relation to the structure of the copper at high current density.

Electrodeposition of Copper

“…Cathode polarization increases slightly at copper sulfate concentrations above 1M (250 g L À1 ) [68]. A concentration of less than 60 g L À1 copper sulfate results in a decreased cathode efficiency [69].…”

“…The concentration of copper sulfate is not particularly critical, although the resistivity of the solution is greater when the concentration is increased [67]. Cathode polarization increases slightly at copper sulfate concentrations above 1M (250 g L À1 ) [68]. A concentration of less than 60 g L À1 copper sulfate results in a decreased cathode efficiency [69].…”

“…Changes in sulfuric acid concentration have more influence than changes in copper sulfate concentration on anode and cathode polarization and on solution conductivity. Cathode polarization decreases when a small amount of sulfuric acid is added to a solution of copper sulfate, reaches a minimum at about 0.4 M (38 g L À1 ), and increases with a further increase in sulfuric acid concentration [68]. Throwing power increases dramatically in low-copper (15 g L À1 ), highsulfuric-acid solutions [71].…”

“…Deposition potentials are generally higher when addition agents are added. Cathode polarization is greatly increased by adding gelatin (0.2 g L À1 ) [70,116] or glue [68,117]. These additions result in grain refinement, but this is chiefly unidirectional because the structure remains columnar and becomes more fibrous [70].…”