Corrosion and Wear Resistance of Thick Chromium Deposits from Accelerated Cr(III) Electrolytes
| Autor: | A. Watson, D.T. Gawne, S. K. Ibrahim |
|---|---|
| Rok vydání: | 1998 |
| Předmět: |
Materials science
Formic acid 020209 energy Inorganic chemistry chemistry.chemical_element 02 engineering and technology Electrolyte engineering.material 01 natural sciences Corrosion Chromium chemistry.chemical_compound Coating Plating 0103 physical sciences 0202 electrical engineering electronic engineering information engineering Hexavalent chromium 010302 applied physics Metallurgy Metals and Alloys Surfaces and Interfaces Condensed Matter Physics Surfaces Coatings and Films chemistry Mechanics of Materials engineering Methanol |
| Zdroj: | Transactions of the IMF. 76:156-161 |
| ISSN: | 1745-9192 0020-2967 |
| DOI: | 10.1080/00202967.1998.11871216 |
| Popis: | SummaryA study of a number of chromium(III) electrolytes has indicated that the unacceptably low deposition rate from such electrolytes is due to the formation of μ-hydroxo bridged oligomers, which adsorb and poison the crystal growth sites. Methanol and formic acid have been shown to be particularly effective in delaying oligomer formation. An environmentally acceptable trivalent chromium electrolyte with optimized additions of methanol and formic acid has been developed. The hydroxo-bridged oligomers in the nonmethanolic bath produce a fine dispersion and this together with a high residual stress gives an exceptionally hard, brittle coating with a high wear rate. A minimum in wear rate is obtained at 20% methanol in the bath, at which the wear is slightly less than that of conventional hexavalent chromium plating. Corrosion initiates at cracks in the coating and their high residual stress levels at low methanol concentrations, in the electrolyte, generate wide through-thickness cracks and high corrosion... |
| Databáze: | OpenAIRE |
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