The electrodeposition of Cu-Zn-Sn alloys from alkaline cyanide solutions
The electrodeposition of Cu-Zn-Sn alloys from alkaline cyanide solutions
The electrodeposition of Cu-Zn-Sn alloys from a commercial alkaline cyanide bath has been investigated. Cyclic voltammetry, potential step and chronopotentiomtric experiments were carried out to investigate the mechanism of electrodeposition of the alloy. Also, Hull cell deposition experiments and plating of brass strips at both constant current and constant potential were carried out. Deposits were examined by SEM and EDS to define their morphology and composition. These deposits from freshly prepared solutions were compared with plates using commercial bath solutions as well as the coatings produced on components on the commercial plating line (both those deemed satisfactory and those with defects).
Voltammetry of the solution with optimized composition showed that the deposition of Cu-Zn-Sn alloy is a complex process which is kinetically controlled by chemical reactions in homogenous solution. Also, it is found that a highly reflective alloy deposit with a composition in the range 47 - 51 % copper, 8 - 12 % zinc and 38 - 43 % tin can be obtained under a range of conditions from this bath. These deposits were of uniform appearance and made of overlapping rounded but rather flat features.
Studies were performed where the concentration of one component of the alkaline cyanide solutions was varied systematically (e.g. the concentrations of free CN, free OH, metal ions, additive) and this enabled correlations to be deduced between the types of defects found on rejected connectors with plating conditions. For example, a "tiger stripe" deposit could be replicated in the laboratory with solutions which were high in hydroxide or copper ions but low in tin or cyanide ions or by using a high current density. There were rough deposits composed of many overlapping centers and were found to have a high copper and a low time content. A "tarnished" deposit could be replicated from solutions low in hydroxide or copper ions or high in tin or cyanide ions. These were deposits composed of angular crystallites which had a high tin and a low copper concentration. Many of the bath characteristics can be understood in terms of speciation of the metal ions in the plating bath.
University of Southampton
Picincu, Lucica
4f83faf9-99a2-4d06-b4e1-6c66449cb431
2000
Picincu, Lucica
4f83faf9-99a2-4d06-b4e1-6c66449cb431
Picincu, Lucica
(2000)
The electrodeposition of Cu-Zn-Sn alloys from alkaline cyanide solutions.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
The electrodeposition of Cu-Zn-Sn alloys from a commercial alkaline cyanide bath has been investigated. Cyclic voltammetry, potential step and chronopotentiomtric experiments were carried out to investigate the mechanism of electrodeposition of the alloy. Also, Hull cell deposition experiments and plating of brass strips at both constant current and constant potential were carried out. Deposits were examined by SEM and EDS to define their morphology and composition. These deposits from freshly prepared solutions were compared with plates using commercial bath solutions as well as the coatings produced on components on the commercial plating line (both those deemed satisfactory and those with defects).
Voltammetry of the solution with optimized composition showed that the deposition of Cu-Zn-Sn alloy is a complex process which is kinetically controlled by chemical reactions in homogenous solution. Also, it is found that a highly reflective alloy deposit with a composition in the range 47 - 51 % copper, 8 - 12 % zinc and 38 - 43 % tin can be obtained under a range of conditions from this bath. These deposits were of uniform appearance and made of overlapping rounded but rather flat features.
Studies were performed where the concentration of one component of the alkaline cyanide solutions was varied systematically (e.g. the concentrations of free CN, free OH, metal ions, additive) and this enabled correlations to be deduced between the types of defects found on rejected connectors with plating conditions. For example, a "tiger stripe" deposit could be replicated in the laboratory with solutions which were high in hydroxide or copper ions but low in tin or cyanide ions or by using a high current density. There were rough deposits composed of many overlapping centers and were found to have a high copper and a low time content. A "tarnished" deposit could be replicated from solutions low in hydroxide or copper ions or high in tin or cyanide ions. These were deposits composed of angular crystallites which had a high tin and a low copper concentration. Many of the bath characteristics can be understood in terms of speciation of the metal ions in the plating bath.
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Published date: 2000
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Local EPrints ID: 464064
URI: http://eprints.soton.ac.uk/id/eprint/464064
PURE UUID: 3bc5e7af-6f27-4efe-b519-f84ab8246e89
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Date deposited: 04 Jul 2022 21:01
Last modified: 16 Mar 2024 19:07
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Author:
Lucica Picincu
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