Micromorphological Studies of the Corrosion of Gold Alloys

Forty, Adrian

doi:10.1007/bf03216556

Cited by 48 publications

(17 citation statements)

References 13 publications

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“…Silver is less noble than gold and releases easily from the gold alloy system, by leaving a high content of gold residue behind and creating surface vacancies and disordered areas near the surface. When all the surface of alloy is dominated by gold atoms, alloy becomes passivated, and volume and surface diffusions start to play an important role [7].…”

Section: Introductionmentioning

confidence: 99%

Effect of gold alloying on stability of silver nanoparticles and control of silver ion release from vapor-deposited Ag–Au/polytetrafluoroethylene nanocomposites

et al. 2012

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In the present study, nanocomposites containing Ag-Au alloy nanoparticle ensembles with various compositions on polytetrafluoroethylene were prepared by physical vapor deposition. After a certain time of immersion of the samples in water, oxidation and dissolution of the Ag nanoparticles (AgNPs) occurred, and changes in the morphology, optical properties and composition of the nanocomposites were examined using transmission electron microscopy, ultraviolet-visible spectroscopy and X-ray photoelectron spectroscopy (XPS), respectively. The composition-dependence and the time-dependence of the silver ion release were studied, and the concentration of the silver ions in water was detected using inductively coupled plasma mass spectrometry. The results indicate that with increasing gold fraction in the AuAg alloy nanoparticles, a strong improvement of the oxidation resistance of the AgNPs occurs. The dissolution of Ag is rapid at the first contact of the sample with water until a saturation state is reached. XPS synchrotron measurements with different excitation energies show that the depletion of Ag from the nanoparticles does not lead to the formation of a Au-rich shell and that the atomic mobility is high enough in the small nanoparticles of about 5 nm average size to equilibrate any concentration gradient.

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Section: Introductionmentioning

confidence: 99%

Effect of gold alloying on stability of silver nanoparticles and control of silver ion release from vapor-deposited Ag–Au/polytetrafluoroethylene nanocomposites

et al. 2012

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“…Although interest in NP Au foams arose recently after a pioneering work from the 1960s and 1970s [51,[55][56][57], the fabrication method and material are remarkably ancient. In the twelfth century, layers of nearly pure Au were manufactured by pre-Columbian civilizations by depletion gilding, a special case of de-alloying based on the removal of other metals from the surface of Au alloys via surface enrichment processes [58,59].…”

Section: Np Au As the Typical Case Studymentioning

confidence: 99%

Mechanical Properties of Nanoporous Au: From Empirical Evidence to Phenomenological Modeling

Pia

Delogu

2015

Metals

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Abstract:The present work focuses on the development of a theoretical model aimed at relating the mechanical properties of nanoporous metals to the bending response of thick ligaments. The model describes the structure of nanoporous metal foams in terms of an idealized regular lattice of massive cubic nodes and thick ligaments with square cross-sections. Following a general introduction to the subject, model predictions are compared with Young's modulus and the yield strength of nanoporous Au foams determined experimentally and available in literature. It is shown that the model provides a quantitative description of the elastic and plastic deformation behavior of nanoporous metals, reproducing to a satisfactory extent the experimental Young's modulus and yield strength values of nanoporous Au.

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“…Mechanisms for attack of the selective dissolution of the more active atoms (alloying species) is influenced by a number of factors to include (1) the activation energy or overpotential to remove these species; (2) presence of these atoms within the lattice, for example at kink sites where removal of atoms is easier and (3) migration of lattice vacancies and diffusion of the more noble species (gold) to form clusters/islands. For high gold alloys, passivation is ultimately achieved, however for low gold alloys, micromorphological studies have shown ultimate disintegration of the alloy may occur through the development of tunnels or pits [14]. For heterogeneous alloys, the mechanism of dissolution becomes more complex as the tendency for corrosion for the different phases present may differ depending on the chemistry of the phases.…”

Section: Atomic Absorption Spectroscopy Analysis Of Gold Alloysmentioning

confidence: 99%

“…The electrochemical corrosion behaviour of a series of Au-Cu-Ag-Pd alloys and the metallurgical dependence has been studied by Nakagawa [13] who reported that single-phase alloys showed superior corrosion resistance than the dual-phase alloys. Forty [14] has studied the selective dissolution of active constituents in gold alloys and found that selective dissolution is more likely to occur in the lower carat gold alloys. Laub and Stanford [15] reported that for ternary Au-Ag-Cu alloys, both copper and silver were involved in the corrosion process; corrosion occurring primarily in the silver-rich regions and secondarily in the copper-rich regions.…”

Section: Introductionmentioning

confidence: 99%

The electrochemical corrosion behaviour of quaternary gold alloys when exposed to 3.5 % NaCl solution

2013

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Lower carat gold alloys, specifically 9 carat gold alloys, containing less than 40 % gold, and alloying additions of silver, copper and zinc, are commonly used in many jewellery applications, to offset high costs and poor mechanical properties associated with pure gold. While gold is considered to be chemically inert, the presence of active alloying additions raises concerns about certain forms of corrosion, particularly selective dissolution of these alloys. The purpose of this study was to systematically study the corrosion behaviour of a series of quaternary gold-silvercopper-zinc alloys using dc potentiodynamic scanning in saline (3.5 % NaCl) environment. Full anodic/cathodic scans were conducted to determine the overall corrosion characteristics of the alloy, followed by selective anodic scans and subsequent morphological and compositional analysis of the alloy surface and corroding media to determine the extent of selective dissolution. Varying degrees of selective dissolution and associated corrosion rates were observed after anodic polarisation in 3.5 % NaCl, depending on the alloy composition. The corrosion behaviour of the alloys was determined by the extent of anodic reactions which induce (1) formation of oxide scales on the alloy surface and or (2) dissolution of Zn and Cu species. In general, the improved corrosion characteristics of alloy #3 was attributed to the composition of Zn/Cu in the alloy and thus favourable microstructure promoting the formation of protective oxide/chloride scales and reducing the extent of Cu and Zn dissolution.

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Micromorphological Studies of the Corrosion of Gold Alloys

Cited by 48 publications

References 13 publications

Effect of gold alloying on stability of silver nanoparticles and control of silver ion release from vapor-deposited Ag–Au/polytetrafluoroethylene nanocomposites

Effect of gold alloying on stability of silver nanoparticles and control of silver ion release from vapor-deposited Ag–Au/polytetrafluoroethylene nanocomposites

Mechanical Properties of Nanoporous Au: From Empirical Evidence to Phenomenological Modeling

The electrochemical corrosion behaviour of quaternary gold alloys when exposed to 3.5 % NaCl solution

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