Influence of organic additives on the behaviour of zinc electroplating from alkaline cyanide-free electrolyte

PAOLA PARY; JOSÉ FERNANDO BENGOA; MARÍA SUSANA CONCONI; SONIA BRUNO; MÓNICA ZAPPONI; WALTER EGLI

TRANSACTIONS OF THE INSTITUTE OF METAL FINISHING

MANEY PUBLISHING

Lugar: Oxford; Año: 2017 vol. 95 p. 83 - 89

0020-2967

Two similar polymeric organic compounds from the polyquaternium family were studied aslevelling additives in an alkaline cyanide-free zinc plating electrolyte. One additive (LA) hasamide bonds between its monomers and the other (LU) has urea unions in its chemicalstructure. Copper cementation on zinc and gas evolution during aging of the zinc coatings wereused to evaluate the effect of the chemical structure of the organic additives on thecharacteristic deleterious aging process of the coatings when electrodeposited with LA.Scanning electron microscopy and X-ray diffraction were used to follow surface morphology andcrystallographic modifications of the coatings during aging. Faster copper cementation kinetics,zinc whiskers growth, blistering of the coating and N2, CH4, CO2 and H2 evolution wereobserved during accelerated aging of the coatings when LA was used. The coatings producedwith LU did not show any aging effect. These studies show the strong influence that subtlechanges in the chemical