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Study of a purple gold-based alloy resistance to tarnishing in a sulphuric solution

✍ Scribed by O. Carvalho; D. Soares; A. Fonseca; F. S. Silva

Book ID
102482311
Publisher
John Wiley and Sons
Year
2009
Tongue
German
Weight
445 KB
Volume
60
Category
Article
ISSN
0947-5117

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✦ Synopsis

Abstract

The stability of some coloured gold alloys is dependent on the environment. In this work, the effect of a sulphuric solution on the physical properties of a purple gold‐based alloy is studied. Changes in the physical properties of the samples namely colour, brightness and reflectance were measured with time in the referred environment. It was observed that significant changes occurred even for a small exposure time. A selective dissolution of aluminium was found to be the main alloy corrosion mechanism, which is responsible for the changes in superficial physical characteristics. At the end of the experiments, the sample surface modification was analyzed by optical and SEM/EDS microscopy. The surface corrosion process resulted in the formation of a large number of superficial fissures with a significant thickness and length, essentially in the Al~2~Au phase. XPS spectroscopy was used in order to identify the compounds formed in the corrosion process.

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