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Bronze disease is an irreversible and nearly inexorable corrosion process that occurs when chlorides come into contact with bronze or other copper-bearing alloys. [1] It can occur as both a dark green coating, or as a much lighter whitish fuzzy or furry green coating. [ 1 ]
They are bronze casts with some silver-colored parts, which originate from the Anatolian region. [2] Similar processes can be found on some ancient Egyptian copper sheets. [ 3 ] Another example of early chemical coloring of metals is the Nebra sky disk , which has a green patina and gold inlays.
After the First World War, the first procedures for anodic oxidation and coloring of anodically oxidized aluminium were developed (1923, 1924.DRP. 413876). In the 1960s, procedures were developed for the anodic oxidation of titanium, a little later niobium and tantalum, and a little bit earlier stainless steel (circa 1957 patent US 2957812 A). [15]
Bronze is usually nonmagnetic, but certain alloys containing iron or nickel may have magnetic properties. Bronze typically oxidizes only superficially; once a copper oxide (eventually becoming copper carbonate) layer is formed, the underlying metal is protected from further corrosion. This can be seen on statues from the Hellenistic period.
Patina (/ p ə ˈ t iː n ə / pə-TEE-nə or / ˈ p æ t ɪ n ə / PAT-ih-nə) is a thin layer that variously forms on the surface of copper, brass, bronze, and similar metals and metal alloys (tarnish produced by oxidation or other chemical processes), or certain stones [1] and wooden furniture (sheen produced by age, wear, and polishing), or ...
The chemical elements can be broadly divided into metals, metalloids, and nonmetals according to their shared physical and chemical properties.All elemental metals have a shiny appearance (at least when freshly polished); are good conductors of heat and electricity; form alloys with other metallic elements; and have at least one basic oxide.
Diamond is extremely strong owing to its crystal structure, known as diamond cubic, in which each carbon atom has four neighbors covalently bonded to it. Bulk cubic boron nitride (c-BN) is nearly as hard as diamond. Diamond reacts with some materials, such as steel, and c-BN wears less when cutting or abrading such material. [4]
Diamond demonstrates both high thermal conductivity and electrically insulating properties, and much attention has been put into finding practical applications of this material. However, diamond has several limitations for mass industrial application, including its high cost and oxidation at temperatures above 800 °C.