What are the causes of silver corrosion?
In ancient times, gold and silverware was considered to have the effect of prolonging life and immortality, and it was highly appreciated by people. Today, silverware is a symbol of purity because of its white and bright color, and it is also favored by people. What are the causes of silver corrosion?
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Humidity effect
Although silver is considered to be an inactive precious metal, it easily absorbs water molecules in the atmosphere and forms a water film on the surface. Sulfur, oxygen and chlorine in the air enter the water film to form insoluble silver sulfide, silver oxide and silver chloride. Corrosion occurs on the surface of the silver layer to cause discoloration. In addition, the rougher the surface of the silver, the easier it is to condense moisture and enter the corrosive medium, causing discoloration.
Effect of ultraviolet light
The ultraviolet light contained in the sun and artificial light sources (such as fluorescent lamps and mercury lamps) has an aging effect on various cultural relics of different textures, and silverware is no exception. The wavelength of ultraviolet light is from 100 nm to 400 nm (the shorter the wavelength, the higher the energy), and it is divided into: near ultraviolet uva, far ultraviolet uvb and ultra short ultraviolet uvc. When ultraviolet light illuminates the surface of the silverware, the silver atoms capture high-energy photons, transition from a stable low-energy state into an unstable high-energy state, which is characterized by silver ionization, which ultimately accelerates the corrosion discoloration of silver.
Air pollution impact
The silver standard potential is quasi-ag+/ag=0.799v. Due to the development of industrialization and the thick smoke emitted by the large amount of burning wheat straw in the countryside, the sulfur content in the air will increase continuously. In this environment, the surface is prone to black or yellow film, and the silver which has been oxidized is exposed. In the case of sulfur-containing air, the film also transforms into sulfide and discolors.
What are the causes of silver corrosion? Corrosion of an object is not caused by a single factor, but by the interaction of various complex factors in the environment in which it was then.
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