Additives for non-cyanide alkaline zinc electroplating: influence on the properties of the deposits
Over the last decades, one of the most currently used processes for batch zinc electroplating has been the alkaline cyanide process. Due to the environmental and safety problems of cyanides, other alternatives have been developed. Good results have been achieved regarding crystallographic structure...
Guardado en:
| Autores principales: | , , |
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| Formato: | Objeto de conferencia |
| Lenguaje: | Español |
| Publicado: |
2012
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| Materias: | |
| Acceso en línea: | http://sedici.unlp.edu.ar/handle/10915/78731 |
| Aporte de: |
| Sumario: | Over the last decades, one of the most currently used processes for batch zinc electroplating has been the alkaline cyanide process. Due to the environmental and safety problems of cyanides, other alternatives have been developed.
Good results have been achieved regarding crystallographic structure and surface appearance on zinc deposits obtained with cyanide-free formulations, both in basic research and industrial processes.
Generally, a brightening agent and a leveling agent are used and the joined effect of both additives leads to high quality deposits. Numerous formulations exist in the market and most of them are complex mixtures.
In this work leveling agents based in polyethylene glycols of different molecular weights were tested and the influence of the molecular size on the properties of zinc coatings deposited on steel tubes was studied.
The additives were characterized by electrochemical techniques. Hull cell tests were performed to study the effect of the additives on high and low current density areas. A rotating cylinder electrode cell was built to simulate industrial conditions and the deposits were characterized by scanning electronic microscopy and X-ray diffraction.
The results show how molecular size of leveling agents change zinc crystals structure and how this structure can modify the coatings properties. |
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