The sulphidation of metals and alloys

Strafford, K.N.

doi:10.1179/mtlr.1969.14.1.153

Cited by 8 publications

(6 citation statements)

References 32 publications

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“…1, analysis A2), indicating a selective corrosion of copper in sterling silver. Standard free energy of formation at room temperature of copper sulphide is lower than silver sulphide, so the reaction of sulphur with copper is thermodynamically favored [29].…”

Section: Silver Tarnishingmentioning

confidence: 99%

A comparative study of cleaning methods for tarnished silver

Palomar

Barat

Garcia

et al. 2016

Journal of Cultural Heritage

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a b s t r a c tTarnishing is produced by reaction of silver with gaseous reduced sulphur compounds from atmospheric pollution. It induces the formation of Ag 2 S crystals which produce a dark appearance. To remove sulphur tarnishing, different mechanical, chemical and electrochemical methods have been traditionally used. To assess the effect of different cleaning treatments on tarnished silver, coupons of pure and sterling silver (92% Ag/8% Cu) were subjected to six cycles of induced tarnishing and cleaning. The cleaning methods evaluated were mechanical (soft abrasives and rubber point mounted on a rotary tool); chemical (chelating and acid solutions) and electrochemical (potentiostatic reductions). Surface morphology, composition, weight, color and luminosity were evaluated by optical microscopy, scanning electron microscopy/energy dispersive X-ray spectroscopy, atomic force microscopy, X-ray photoelectron spectroscopy and colorimetry. The cleaning impact on tarnished silver depended on the cleaning procedure and the composition of silver. Mechanical treatments restored the original visual appearance of silver although they produced a significant mass loss and a fast re-tarnishing. Chemical cleaning methods were fast; nevertheless the surface appeared completely attacked. Electrochemical cleaning did not yield good result for sterling silver, but was an effective cleaning method for pure silver coupons. Different cleaning methods have been used for many years to remove sulphur tarnishing from silver. However, scientific studies which assess the treatment's impact on silver and the re-tarnishing rate are very scarce. Costa [1] carried out a complete bibliographic study about the cleaning procedures and their applications, although the results of these different scientific works are difficult to compare since they have not been systematically evaluated in similar conditions and materials.The aim of this study is to quantitatively assess the efficiency, residues left on the metal and impact on the base metal of eleven mechanical, chemical and electrochemical cleaning methods to remove tarnishing on pure and sterling silver. To evaluate the effect in the long term, several cycles of tarnishing/cleaning are considered.

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Section: Silver Tarnishingmentioning

confidence: 99%

A comparative study of cleaning methods for tarnished silver

Palomar

Barat

Garcia

et al. 2016

Journal of Cultural Heritage

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“…In 1929, Hauck conducted a study that found “true” black dermographism, in which the black smudge appeared without any previous preparation of the skin, occurred in 2.7% of those studied . For this subset of people, a chemical theory has been postulated that black dermographism is a reaction of metal with labile sulfur compounds in the sweat, and that sulfur-containing amino acid concentrations are hormonally controlled . This chemical reaction could potentially explain historic reports correlating black dermographism with the menstrual cycle .…”

Section: Discussionmentioning

confidence: 99%

“…The idea that genetic predisposition is involved in PP is further supported by recent reports describing 3 cases of PP with segmental distribution suggesting a genetic cutaneous mosaicism. 5,6 The presence of neutrophils in the inflam-…”

Section: Prurigo Pigmentosa In White Monozygotic Twinsmentioning

confidence: 99%

“…4 For this subset of people, a chemical theory has been postulated that black dermographism is a reaction of metal with labile sulfur compounds in the sweat, and that sulfur-containing amino acid concentrations are hormonally controlled. 3,5 This chemical reaction could potentially explain historic reports correlating black dermographism with the menstrual cycle. 6 More scientific data need to be col- A, Rubbing her face with an 18-karat gold ring produces black smudges.…”

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confidence: 96%

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Black Dermographism

Lowe

Lim²

2017

JAMA Dermatol

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“…where In the parabolic oxidation law, the first term represents the scale growth under the diffusion-controlled regime and the second term represents the scale growth under the reaction-controlled regime. Strafford established that scale growth during sulfidation is primarily diffusion-controlled [22]. Therefore, only the first term of the parabolic oxidation law was considered for simplicity.…”

Section: Metal Consumption Model Derivationmentioning

confidence: 99%

Sulfidation kinetics of titanium and Ti-6Al-4V with elemental sulfur

Raikar

DiGregorio

Hildreth

2023

Corrosion Engineering, Science and Technology

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The sulfidation kinetics of titanium and Ti-6Al-4V (Ti64) using elemental sulfur were studied by measuring the amount of metal consumed instead of the change in mass or scale thickness. This metal consumption approach combines the parabolic oxidation law, Arrhenius equation, and Pilling-Bedworth ratio to determine the apparent activation energy and the pre-exponential factor of consumption of Ti64 during sulfidation. The estimations of apparent activation energy and preexponential factor were 110.4 kJ•mol −1 and 1.3 × 10 −9 m 2 s −1 for the titanium-sulfur, and 116.2 kJ•mol −1 and 1.2 × 10 −9 m 2 s −1 for the Ti64-sulfur system. Finally, a material removal predictor was developed to predict the amount of Ti64 consumed for a given sulfidation temperature and time.

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The sulphidation of metals and alloys

Cited by 8 publications

References 32 publications

A comparative study of cleaning methods for tarnished silver

A comparative study of cleaning methods for tarnished silver

Black Dermographism

Sulfidation kinetics of titanium and Ti-6Al-4V with elemental sulfur

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