The corrosion of silver by atmospheric sulfurous gases

Franey, J. P.; Kammlott, G. W.; Graedel, T. E.

doi:10.1016/0010-938x(85)90104-0

Cited by 211 publications

(171 citation statements)

References 22 publications

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“…If the exposure time is lengthened, the sulfide ions react with the metallic silver and form silver sulfide (Ag 2 S). Franey et al demonstrated that the rate of silver sulfidation by SO 2 is more than two orders of magnitude lower than that by reduced sulfur, such as H 2 S and COS. 12) However, the S 2p spectra we obtained for the silver suggests that the contribution of SO 2 to silver sulfidation is significant if, as we assume, the broad peak at around 162 eV is mainly due to the sulfide. It is well known that Ag 2 S is a thermodynamically stable phase and that silver does not form sulfate under ordinary conditions.…”

Section: )mentioning

confidence: 73%

“…Moreover, the formation rate of sulfite was higher than that of sulfate in the very early stage. 17) 18) In contrast, the sulfidation rate by SO 2 for silver is much lower than that by reduced sulfur species, such as H 2 S and COS. 12) Since SO 2 is considered to be a weak corrosive agent for silver, the effect of SO 2 on atmospheric silver corrosion in the initial stage has received little attention.…”

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confidence: 99%

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Comparative XPS Study of Silver and Copper Surfaces Exposed to Flowing Air Containing Low Concentration of Sulfur Dioxide

Watanabe

Andō²,

Handa

et al. 2007

ZAKAEP

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Sulfur dioxide (SO 2 ), a typical gaseous compound found in the atmosphere, corrodes metals, particularly outdoors. When SO 2 adsorbs on the surface electrolyte, it easily dissolves, resulting in the formation of protons (H ) and bisulfite ions (HSO 3 ). The former reduces the pH of the surface electrolyte, which promotes metal dissolution.Silver and copper are commonly used in the electronic components and devices typically found in telecommunication equipment. Since silver and copper are affected by SO 2 , it is important to know the effects of SO 2 on their corrosion behavior to predict the life expectancy of the equipment. Such knowledge would also be useful for coping with anomalous situations, such as volcanic eruptions, in which the SO 2 concentration can exceed several hundred ppb. A previous study showed that silver and copper plates exposed to the atmosphere were severely corroded following the volcanic eruption on Miyake Island in 2000. 1)Much effort has been expended on clarifying the effects of SO 2 on atmospheric silver and copper corrosion. A number of laboratory experiments have been reported regarding the effects of exposure to high SO 2 concentrations. 2) 15)Using infrared reflection absorption spectroscopy (IRAS), Persson and Leygraf showed that sulfite formed on the surface of copper during the initial stage when it was exposed to 0.21 ppm SO 2 in flowing air at 80 relative humidity (RH).16) In situ analysis using IRAS and a quartz crystal microbalance by Ito et al.17) 18) revealed that sulfite like CuSO 3 Cu 2 SO 3 2H 2 O (Chevreul's salt) and sulfate CuSO 4 5H 2 O formed as corrosion products on copper exposed to flowing air containing 10 ppm SO 2 at 80 RH. Moreover, the formation rate of sulfite was higher than that of sulfate in the very early stage. 17) 18) In contrast, the sulfidation rate by SO 2 for silver is much lower than that by reduced sulfur species, such as H 2 S and COS. 12) Since SO 2 is considered to be a weak corrosive agent for silver, the effect of SO 2 on atmospheric silver corrosion in the initial stage has received little attention.In this study, the chemical state of the sulfur was investigated when silver and copper plates were exposed for one hour to flowing air containing low concentrations of SO 2 . Since the electrochemical reactions occur at the metal/ electrolyte interface in the early stage of corrosion, X-ray photoelectron spectroscopy (XPS) was used. The SO 2 concentrations were 18 and 148 ppb ; the former is at least one order of magnitude lower than those in previous studies. 16) 18)The silver and copper plates were 99.99 pure and 5 5 0.1 mm in size. Their surfaces were sputtered with 3 kV Ar ions to clean them. The sputtering was conducted until both carbon and oxygen were not detected in the XPS spectra, as described elsewhere. Sulfur dioxide (SO 2 ) is a typical gas affecting the atmospheric corrosion of metals, particularly outdoors. Although many studies have investigated the effect of SO 2 on the atmospheric corrosion of silver and copper, little is ...

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Section: )mentioning

confidence: 73%

mentioning

confidence: 99%

Comparative XPS Study of Silver and Copper Surfaces Exposed to Flowing Air Containing Low Concentration of Sulfur Dioxide

Watanabe

Andō²,

Handa

et al. 2007

ZAKAEP

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“…In the presence of such substances, the high specular reflectivity of silver is degraded by sulfidation, chloridation and oxidation with corrosive chemicals [4][5][6][7][8][9][10][11][12][13][14] 4 and Ag 2 CO 3 in increasing order of solubility. Since these products form in the thin water layer which is typically present on silver, the most likely precipitate is Ag 2 S. Depending on its thickness, an absorbing Ag 2 S film can reduce the Ag reflectance to zero.…”

Section: Fig 2 Reflectance Of Evaporated Metals In the Visible And Imentioning

confidence: 99%

<title>UV-shifted durable silver coating for astronomical mirrors</title>

Thomas

Wolfe

2000

SPIE Proceedings

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Silver has the highest reflectance of all of the metals, but it tarnishes in the presence of sulfides, chlorides, and oxides in the atmosphere. Also, the silver reflectance is very low at wavelengths below 400 nm making aluminum more desirable mirror coating for the UV region. We have found a way to prevent silver tarnishing by sandwiching the silver layer between two thin layers of NiCrN x , and to extend the metal's high reflectance down to 200 nm by depositing the (thin) Ag layer on top of Al. Thus, the uv is transmitted through the thin Ag layer below 400 nm wavelength, and is reflected from the Al layer underneath. This UV-shifted durable coating 1 provides a valuable alternative to the aluminum coating for telescope mirror coatings where high throughput and durability are important considerations. The throughput for a telescope with, say, six reflections from silver coatings is (0.97) 6 = 83% compared to (0.92) 6 = 60% for aluminum coatings, or 28% less. The use of silver coatings allows more photons to be collected by primary mirror. Aluminum also has a reflectance dip at 850 nm caused by inter-band transitions which is eliminated by placing the thin Ag layer on top. This paper describes a nontarnishing silver coating having high reflectance down into the UV region. The average specular reflectance is 70% -97% in the near-UV, 95% -99% in the visible region, and ≥ 99% in the infrared region covering the total wavelength range 200 nm to 10,000 nm. Figure 1 compares the reflectance of our UVHR-LLNL silver coating to bare silver and aluminum overcoated with magnesium fluoride over the wavelength range 300 nm to 2000 nm.

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“…Silver degradation has been studied in different environments [1] and extensive studies have been carried out regarding the embrittlement of buried silver objects [2,3]. One of the main degradation processes affecting silver artefacts is the corrosion due to atmosphere gases [4]. This is nowadays one of the most critical issue for objects conserved in collections.…”

Section: Introductionmentioning

confidence: 99%

Surface micro-profilometry for the assessment of the effects of traditional and innovative cleaning treatments of silver

Daffara¹,

Gaburro²,

Marchioro³

et al. 2017

Proceedings of the International Conference LACONA XI

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In the complex procedure for the conservation of a work of art, the effective monitoring of the surface treatment is an important step in order to establish a conservation protocol. The evaluation of the effects of the cleaning requires the inspection of the outermost layer with complementary diagnostic techniques to obtain information on both materials and surface morphology. In this interdisciplinary work, a custom optical micro-profilometry device based on laser conoscopic holography was used for testing the performance of different mechanical procedures for the cleaning of silver alloy objects. Tarnishing is the main alteration phenomenon for silver alloy artworks. Even if such modification does not affect the long-term preservation of the objects, it heavily influences aesthetical features, making the removal of tarnishing one of the most important conservation treatments of the case. The mechanical cleaning procedure based on abrasive powders suspended in a liquid matrix is of widespread use. Recently, a novel dry cleaning procedure based on the use of erasers was proposed as alternative method and tested for both the efficacy of tarnishing removal and effects on the surface appearance using optical microscopy and scanning electron microscopy. However, the employed laboratory techniques cannot provide an objective measure of the roughness at micrometric scale over the sample. In this work, the effects on the surface structure of traditional and innovative silver treatments was investigated with multiscale profilometry, using scanning conoscopic holography and atomic-force microscopy. 3D surface metrology was carried out using standard areal amplitude parameters and a multiscale approach. Preliminary results are presented, addressing two aspects: 1) the validation of laser optical micro-profilometry for the diagnostics of silver objects, which are challenging due to the highly specular surface; 2) the validation of the dry-cleaning treatment based on rubbers, by adding to the previous study the complimentary analysis of the micro-surface. The results obtained on silver mockups confirm that the proposed dry cleaning methods produce surface variations less or similar to traditional methods. The optical micro-profilometry results are of particular significance since this technique is portable with wide field capability, thus allowing an in-situ use and a real monitoring of actual artwork surfaces.

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The corrosion of silver by atmospheric sulfurous gases

Cited by 211 publications

References 22 publications

Comparative XPS Study of Silver and Copper Surfaces Exposed to Flowing Air Containing Low Concentration of Sulfur Dioxide

Comparative XPS Study of Silver and Copper Surfaces Exposed to Flowing Air Containing Low Concentration of Sulfur Dioxide

<title>UV-shifted durable silver coating for astronomical mirrors</title>

Surface micro-profilometry for the assessment of the effects of traditional and innovative cleaning treatments of silver

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