Quantitative Ohmic model for transient growths of passivating films

Voltammetric growth of tin oxides in borate solution of pH 8.7

“…At the same time, the representation of ρf vs. charge density of the film presents a minimum. This behavior was also found by other authors in the cases of Zn, Nb, Ni and galvanized steel sheets [12][13][14][15][16][17].…”

“…This result shows that the charge required for film growth up to peak potential becomes constant for sweep rates higher than 0.10 V s -1 . According to D'Alkaine [13] this means that the parameters related to the film (aging phenomenon) become independent of the growing conditions for sweep rates higher than 0.10 V s -1 . In view of this fact, the variable ionic resistivities were studied for 2 and 100 mV s -1 .…”

“…The ohmic model developed by D'Alkaine [12][13][14][15][16][17] presented in earlier work, describes the relation between the current density and the film overpotential during the growth of passivating film under voltammetric conditions. The following equation should be valid for peak or plateau transient conditions during voltammetric growth of a film:…”

“…In order to calculate the values of ρf using Eq. (4), many authors [12][13][14][15][16][17] applied the ohmic model, considering the volume per charge unit (Vf) as the constant equal to:…”

Avaliação do efeito da concentração de carbonato na eletrodeposição de cobre sobre discos de aço-carbono

“…15 A espessura da película (camada depositada) e suas propriedades dependem de diversos fatores: densidade da corrente aplicada, concentração dos sais, temperatura do banho, presença de aditivos, natureza do metal de base, agitação do banho, pH etc. 12,13,16 A quantidade de metal eletrodepositado determina a massa e as dimensões finais das peças tratadas. Por isso, a quantidade de depósito tem que ser controlada dentro de tolerâncias muito restritas para que a peça final esteja dentro de suas especificações.…”