The Influence of Gaseous Pollutants on Silver Artifacts Tarnishing

Abstract

The present work investigated the effect of the common gaseous pollutants on silver artifacts corrosion. The study will be carried out on manufactured coupons of silver alloy (91 silver, 9 copper) which have chemical composition similar to ancient Egyptian silver artifacts. These coupons will be exposed to gaseous pollutants of each individual gas; such as Sulfur dioxide, Nitrogen dioxide, Carbon dioxide, Hydrogen sulfide and Chlorine. The exposure period will be four weeks in a climate chamber with gas concentration 10 PPM. After the test Examinations by SEM and PM were used to evaluate the effect of each gas and description the morphology of the corrosion layers. The results revealed that all gases reacted with the surface except carbon dioxide. The formed tarnishing layers varied in coverage and density rate. Corrosion products are analyzed by XRD and the results revealed Ag 2 S, AgCl, Ag 2 SO 4 and Ag 2 O as corrosion products.

Insights into the high-sulphur aging of sintered silver nanoparticles: An experimental and ReaxFF study

“…Silver becomes tarnished at ambient pressure when exposed to atmospheric environments due to the presence of corrosive substances, such as SO 2 , SO 3 , O 2 , and O 3 [18,19]. In addition, the influence factors, such as the relative humidity and concentrations of sulphur and ozone, have also been widely reported [20][21][22]. Furthermore, a considerate amount of literature has been published on silver tarnishing simulations.…”

Material Characteristics and Comparison of Silver Foil Glass Beads Excavated from the Tomb of King Muryeong in Korea

“…Pure silver was detected in the metal foils of both the gold and silver foil beads, which indicates that they were not alloyed with other materials. Deviation in the amount of silver varies considerably depending on the proportions of the detected S, Cl, Br, and O, which are considered to be corrosive compounds [11,12]. Therefore, the gold and silver foil beads excavated from the Tomb of King Muryeong were all interpreted to be de Facto silver foil beads because the metal foils were identified as silver foil.…”

Evaluation of Inhibition Efficiency of Oak Galls Extract as a Green Corrosion Inhibitor of Archaeological Iron Artifacts in the Atmospheric Environment

“…The museum environment provides metallic artifacts with the protection against many damage factors that affect the artifacts in the outdoor environment such as frost, dew, rain and high concentrations of air pollutants 25 . Nevertheless, there are some factors that can increase the activity of corrosion reaction such as relative humidity -especially in storage rooms -and some indoor pollutants 26,27 . The corrosion of iron artifacts in the museum environment depends on a chemical reaction with the main compositions of air: oxygen, humidity, and gaseous pollutants 27 .…”

“…Nevertheless, there are some factors that can increase the activity of corrosion reaction such as relative humidity -especially in storage rooms -and some indoor pollutants 26,27 . The corrosion of iron artifacts in the museum environment depends on a chemical reaction with the main compositions of air: oxygen, humidity, and gaseous pollutants 27 . So, the use of relative humidity as a corrosive medium for the evaluation of inhibition efficiency is more realistic of indoor museum environment especially of humid storage conditions 19 .…”