|Shape:||Pigeon||Usage:||Tombstone Cemetery And Other|
Ornamental Coffins Screws
Product name:Brass decoration (Pigeon)
Application: Decoration for Tombstone ,cemetery or others.
Manufacturer: Sumer International (Beijing) Trading Co.,Ltd
Material: Brass (Copper alloy)
Color /finishing:electrophoretic paint
Professionally engaged in funeral field over 10 years;
Customized products acceptable;
Good quality and competitive price;
Brass is susceptible to stress corrosion cracking, especially from ammonia or substances containing or releasing ammonia. The problem is sometimes known as season cracking after it was first discovered in brass cartridges used for rifle ammunition during the 1920s in the British Indian Army. The problem was caused by high residual stresses from cold forming of the cases during manufacture, together with chemical attack from traces of ammonia in the atmosphere. The cartridges were stored in stables and the ammonia concentration rose during the hot summer months, thus initiating brittle cracks. The problem was resolved by annealing the cases, and storing the cartridges elsewhere.
Although forms of brass have been in use since prehistory, its true nature as a copper-zinc alloy was not understood until the post medieval period because the zinc vapor which reacted with copper to make brass was not recognised as a metal.The King James Bible makes many references to "brass".The Shakespearean English form of the word 'brass' can mean any bronze alloy, or copper, rather than the strict modern definition of brass. The earliest brasses may have been natural alloys made by smelting zinc-rich copper ores.By the Roman period brass was being deliberately produced from metallic copper and zinc minerals using the cementation process, and variations on this method continued until the mid-19th century.It was eventually replaced by speltering, the direct alloying of copper and zinc metal which was introduced to Europe in the 16th century.
|Oxidation states||−2, +1, +2, +3, +4 (a mildly basic oxide)|
|Electronegativity||Pauling scale: 1.90|
|Ionization energies||1st: 745.5 kJ/mol
2nd: 1957.9 kJ/mol
3rd: 3555 kJ/mol
|Atomic radius||empirical: 128 pm|
|Covalent radius||132±4 pm|
|Van der Waals radius||140 pm|
Early copper zinc alloys
In West Asia and the Eastern Mediterranean early copper zinc alloys are now known in small numbers from a number of third millennium BC sites in theAegean, Iraq, the United Arab Emirates, Kalmykia, Turkmenistan and Georgia and from 2nd Millennium BC sites in West India, Uzbekistan, Iran, Syria, Iraq and Palestine. However, isolated examples of copper-zinc alloys are known in China from as early as the 5th Millennium BC.
The compositions of these early "brass" objects are highly variable and most have zinc contents of between 5% and 15% wt which is lower than in brass produced by cementation. These may be "natural alloys" manufactured by smelting zinc rich copper ores in redox conditions. Many have similar tin contents to contemporary bronze artefacts and it is possible that some copper-zinc alloys were accidental and perhaps not even distinguished from copper.However the large number of copper-zinc alloys now known suggests that at least some were deliberately manufactured and many have zinc contents of more than 12% wt which would have resulted in a distinctive golden color.
By the 8th–7th century BC Assyrian cuneiform tablets mention the exploitation of the "copper of the mountains" and this may refer to "natural" brass."Oreikhalkon" (mountain copper),the Ancient Greek translation of this term, was later adapted to the Latin aurichalcum meaning "golden copper" which became the standard term for brass. In the 4th century BC Plato knew orichalkos as rare and nearly as valuable as gold and Pliny describes howaurichalcum had come from Cypriot ore deposits which had been exhausted by the 1st century AD. X-ray fluorescence analysis of 39 orichalcum ingots recovered from a 2,600-year-old shipwreck off Sicily found them to be an alloy made with 75–80 percent copper, 15–20 percent zinc and small percentages of nickel, lead and iron.
Brass decoration---vase ring and pigeon
Contact Person: sumer