5 Temel Unsurları için brassestol trä

The bactericidal properties of brass have been observed for centuries, particularly in marine environments where it prevents biofouling.

[79] They show no signs of slag or metal prills suggesting that zinc minerals were heated to produce zinc vapor which reacted with metallic copper in a solid state reaction. The fabric of these crucibles is porous, probably designed to prevent a buildup of pressure, and many have small holes in the lids which may be designed to release pressure[79] or to add additional zinc minerals near the end of the process. Dioscorides mentioned that zinc minerals were used for both the working and finishing of brass, perhaps suggesting secondary additions.[81]

Знай и умей

Historically, the distinction between the two alloys has been less consistent and clear,[3] and çağdaş practice in museums and archaeology increasingly avoids both terms for historical objects in favor of the more general "copper alloy".[4]

The pattern the globules form on the surface of the brass increases the available lead surface area which in turn affects the degree of leaching. In addition, cutting operations dirilik smear the lead globules over the surface. These effects yaşama lead to significant lead leaching from brasses of comparatively low lead content.[12]

The composition of brass, generally 66% copper and 34% zinc, makes it a favorable substitute for copper based jewelry, birli it exhibits greater resistance to corrosion. Brass is often used in situations in which it is important that sparks derece be struck, such bey in fittings and tools used near flammable or explosive materials.[5]

Siden de har bodd her har bile satt seg mest inn i ting, og. Die Areca Palme ist nicht giftig und kann deshalb auch problemlos in einem Haus...

The mouthpieces of both brass instruments and, less commonly, woodwind instruments are often made of brass among other metals as well.

The cementation process continued to be used but literary sources from both Europe and the Islamic world seem to describe variants of a higher temperature liquid process which took place in open-topped crucibles.[92] Islamic cementation seems to have used zinc oxide known birli tutiya or tutty rather than zinc ores for brass-making, resulting in a metal with lower iron impurities.[93] A number of Islamic writers and the 13th century Italian Marco Polo describe how this was obtained by sublimation from zinc ores and condensed onto clay or iron bars, archaeological examples of which have been identified at Kush in Iran.

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.[59] "Oreikhalkon" (mountain copper),[60] the Ancient Greek translation of this term, was later adapted to the Latin aurichalcum meaning brassestol trä "golden copper" which became the standard term for brass.[61] In the 4th century BC Plato knew orichalkos as rare and nearly as valuable bey gold[62] and Pliny describes how aurichalcum had come from Cypriot ore deposits which had been exhausted by the 1st century AD.

To enhance the machinability of brass, lead is often added in concentrations of around 2%. Since lead başmaklık a lower melting point than the other constituents of the brass, it tends to migrate towards the grain boundaries in the form of globules bey it cools from casting.

Eventually it was discovered that metallic zinc could be alloyed with copper to make brass, a process known birli speltering,[109] and by 1657 the German chemist Johann Glauber had recognised that calamine was "nothing else but unmeltable zinc" and that zinc was a "half ripe metal".

Other wind instruments may be constructed of brass or other metals, and indeed most çağdaş student-model flutes and piccolos are made of some variety of brass, usually a cupronickel alloy similar to nickel silver/German silver. Clarinets, especially low clarinets such birli the contrabass and subcontrabass, are sometimes made of mühür because of limited supplies of the dense, fine-grained tropical hardwoods traditionally preferred for smaller woodwinds. For the same reason, some low clarinets, bassoons and contrabassoons feature a hybrid construction, with long, straight sections of wood, and curved joints, neck, and/or bell of mühür.

[94] It could then be used for brass making or medicinal purposes. In 10th century Yemen hile-Hamdani described how spreading hile-iglimiya, probably zinc oxide, onto the surface of molten copper produced tutiya vapor which then reacted with the metal.[95] The 13th century Iranian writer tuzak-Kashani describes a more complex process whereby tutiya was mixed with raisins and gently roasted before being added to the surface of the molten metal. A temporary lid was added at this point presumably to minimise the escape of zinc vapor.[96]