Optimisation of Thiourea Concentration in a Decorative Copper Plating Acid Bath Based on Methanesulfonic Electrolyte

Fabbri, Lorenzo; Giurlani, Walter; Mencherini, Giulia; Luca, Antonio De; Passaponti, Maurizio; Piciollo, Emanuele; Fontanesi, Claudio; Caneschi, Andréa; Innocenti, Massimo

doi:10.3390/coatings12030376

Cited by 15 publications

(4 citation statements)

References 35 publications

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“…This paper considers in more detail one of the most important factors determining the choice of additive-assisted electrolyte composition, namely their influence on the kinetics and mechanism of the electrochemical deposition of copper at the limiting stages of charge transfer and electrocrystallization [6,29,34,39,40]. It is well known that the quality of electrodeposited copper depends on the rate of the early stage of electroplating and especially that of nucleation [41].…”

Section: Introductionmentioning

confidence: 99%

Electrocrystallization and Morphology of Copper Coatings in the Presence of Organic Additives

Kozaderov,

Sotskaya,

Yudenkova

et al. 2023

Coatings

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Copper coatings with refined grains and smooth surface morphology were electrodeposited from electrolytes comprising a novel accelerator, the disodium salt of 4,4-dithiobenzene disulfonic acid (DBDA), with sodium chloride and polyethylene glycol (PEG) as inhibitors and 2-aminobenzothiazole (ABT) as a leveler. It was found that the morphology of the coatings strongly depends on the presence and type of additives. In the presence of only DBDA and NaCl, large crystallites are formed, whereas the addition of PEG and ABT significantly decreases their size, and the most fine-grained, smooth, and defect-free copper coating is formed with the combined use of all additives. To establish the correlation between the observed morphology and the kinetics of the additive-assisted copper electrocrystallization in the proposed electrolytes, the nucleation mechanism and its parameters were determined by transient electrochemical characterization. The extended nucleation model, which takes into account not only the copper deposition but also the electric double-layer charging and hydrogen reduction process, was used to establish the electrocrystallization kinetics in the presence of the additives. The results of such kinetic analyses can help to explain the morphological effect. By using the chronopotentiometry method, it was found that the addition of the disodium salt of 4,4-dithiobenzene disulfonic acid with chloride ions gives a catalytic effect, while the sequential introduction of polyethylene glycol and 2-aminobenzothiazole provides an increasing inhibitory effect. Voltamperometry and chronoamperometry tests showed that the process is controlled by the diffusion of ions to the growing three-dimensional cluster of a new phase. The introduction of additives into the electrolyte slows down the copper electroplating process at comparatively negative potentials and increases the probability of transition from instantaneous to progressive nucleation. Moreover, the rate of the process and the density of nucleation active sites increase (up to 2–3 times) with the addition of DBDA but decrease significantly (up to 5–8 times) in the presence of PEG and ABT, which additionally confirms their catalytic and inhibitory effects, respectively, and explains the significant smoothing effect on the morphology of the Cu-coatings.

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Section: Introductionmentioning

confidence: 99%

Electrocrystallization and Morphology of Copper Coatings in the Presence of Organic Additives

Kozaderov,

Sotskaya,

Yudenkova

et al. 2023

Coatings

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“…At the industrial level, a typical operational practice is the incorporation of additives as a method to control the surface quality of the cathodic product, acting either as metal deposit growth levelers or as grain refiners [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Among the most used additives are animal glue, thiourea, and chloride ion.…”

Section: Introductionmentioning

confidence: 99%

Effect of Glue, Thiourea, and Chloride on the Electrochemical Reduction in CuSO4–H2SO4 Solutions

Nevárez-Llamas

Araneda-Hernández

Parra-Sánchez

et al. 2023

Metals

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The effect of glue, thiourea, and chloride on the kinetics of copper reduction in CuSO4–H2SO4 solutions of copper composition, and temperatures like those used in the copper electrorefining plants, were studied. The kinetic study was conducted by determining the kinetic parameters i0 and β under the activation control of the Tafel approximation, which is applied to polarization curves obtained via linear voltammetry. The results show that the incorporation of glue and thiourea decreases the exchange current density, while chloride does not significantly affect the kinetic parameters. The data on the fraction of the surface covered by glue and thiourea fitted to the Temkin adsorption isotherm indicate that the mechanism of action during the reduction of copper to low overpotentials is the adsorption of these additives on the electrode surface. The adsorption of additives reduces the cathodic area available for Cu2+ adsorption and lateral diffusion of Cu atoms to continue the reduction process and the growth of the crystalline deposit. The kinetic study was complemented with a comprehensive analysis of the effect of the additives on the morphological and textural characteristics of the deposits. The results of this work contribute to the understanding of the mechanisms of the main additives used during the copper electrorefining process.

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“…Nevertheless, alternatives do exist, despite the fact that, from a technological point of view, a lot of work has yet to be done to ensure at least the same performance of the materials nowadays being used [7][8][9]. Since fashion-jewellery market players are constantly seeking new, viable ways to render their whole value chain more sustainable, they are constantly looking at making use of green and eco-compatible base materials, yet ensuring economically feasible processes [10][11][12]. Concerning fashion items and accessories like chains, rings, earrings, bracelets and so on, among a wide variety of suitable base materials, aluminium is one of the most interesting because is unlimitedly recyclable and is spread throughout the world, hence is largely available and cheap [13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Electroplating on Al6082 Aluminium: A New Green and Sustainable Approach

Comparini

Pace²,

Giurlani

et al. 2022

Coatings

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Aluminium and its alloys are interesting for many applications because they are very light, cheap, and unlimitedly recyclable. Despite being a promising base material for the fashion-jewellery sector, their tendency to form a passivating film makes them difficult to be galvanized, even more when recycled aluminium contains impurities of refractory elements. Indeed, the most common processes for galvanising aluminium are often expensive and not environmentally sustainable because they involve the use of cyanides. In this work we focussed on the pre-treatments and electroplating on Al6082 aluminium which is largely used for fashion-jewellery applications. The objective of the present study was to assess whether Al6082 series aluminium is suitable a as base material for the fashion market; therefore, we investigated the effectiveness of plating pre-treatments and the success of electroless zinc deposition using an innovative alkaline cyanide-free zincate solution. After the electroplating, adhesion between the deposited layers was evaluated both with cross-sectional scanning electron microscope (SEM) analysis as well as with an adhesion evaluation test (ISO2819:2018): no detachments confirmed the positive test outcomes and thereby highlighted that Al6082 can be exploited as base material in the fashion-jewellery market.

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Optimisation of Thiourea Concentration in a Decorative Copper Plating Acid Bath Based on Methanesulfonic Electrolyte

Cited by 15 publications

References 35 publications

Electrocrystallization and Morphology of Copper Coatings in the Presence of Organic Additives

Electrocrystallization and Morphology of Copper Coatings in the Presence of Organic Additives

Effect of Glue, Thiourea, and Chloride on the Electrochemical Reduction in CuSO4–H2SO4 Solutions

Electroplating on Al6082 Aluminium: A New Green and Sustainable Approach

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