Ah&a&-The electrodeposition of brasses of varying composition has been studied in CuI-ZnI*formamide solutions at 25ยฐC and 40ยฐC. The zinc content of the deposits increases current density at constant temperature.
with increasing At constant cd the deposits at 40ยฐC are richer in copper than those at 25ยฐC. The structures and compositions of the deposits were examined using metallographic and electron-probe microanalysis techniques. At low cd the deposits were columnar whereas at higher cd they became laminated. Electron-probe microanalysis indicated that under some conditions the 6rst l-2 pm of deposited metal was zinc-rich. It was not found possible to detect compositional changes from lamella to lamella in such deposits using electron-probe microanalysis, although conical growths also present clearly exhibited concentration gradients, being copper-rich at their solution extremities and zinc-rich at the base. Microhardness measurements indicated the presence of both a and y brass is some of the deposits. mixed acetate-acetic acid-pyridine solutions.
Co-deposition of copper and zinc was also studied in Dynamic potential measurements indicated that the Zn and Cu potentials remained ca 850 mV apart at all current densities, and transient studies indicated that co-deposition of hydrogen with copper occurred and was preferred to co-deposition of zinc and copper. R&sum&Etude de l'&ctrodeposition des laitons de differentes compositions dam des solutions dans la formamide de CuI et Zr&, a 25ยฐC et 40ยฐC. augmente quand la densitd du courant crolt. * Manuscript received 8 July 1967. 429 ist zinkreicher und die Losungsseite kupferreicher. Messungen der Mikroharte deuten auf das Vorhandensein sowohl von a-wie von y-Messing in einigen der Abscheidungen. Die simultane Abscheidung von Kupfer und Zink wurde such in gemischten Acetat/Essigs&tre/Pyridinl&mgen untersucht. Dynamische Potentialmessungen zeigen, dass das Zink-und Kupferpotential bei allen Stromdichten ca 850 mV Unterschied aufweist. Die Ergebnisse der instationlren Messungen deuten weiter darauf hin, dass mit Kupfer vorherrschend Wasserstoff abgeschieden wird zu ungunsten der simultanen Abscheidung von Zink und Kupfer.