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metal | 21 août 2007

Publié par Tolar à 18:40:39 dans Metal MMaxi | Commentaires (0) | Permaliens

Metal | 13 juillet 2007

Bronze is any of a broad range of copper alloys, usually with tin as the main additive, but sometimes with other elements such as phosphorus, manganese, aluminium, or silicon. It is strong, tough and has myriad uses in industry. It was particularly significant in antiquity, giving its name to the Bronze Age. That name, in turn, is perhaps ultimately taken from the Persian word "birinj," meaning "copper".

Publié par Tolar à 13:47:29 dans Metal MMaxi | Commentaires (0) | Permaliens

Metal | 23 mars 2007

A cannon is any large tubular firearm designed to fire a heavy projectile over a long distance. The cannon is the archetypical form of artillery.
Cannon comes through Old French from Old Italian cannone, ultimately derived from Latin canna—a tube. The Latinised word canon was used for a gun since 1326 in Italy, and 1418 in England. Bombardum, or "bombard", was earliest used for "cannon", but from 1430 it came to refer only to the largest weapons."Cannon" serves both as the singular and plural of the noun, although the plural "cannons" can also be used. The term can apply to a modern day rifled machine gun with a calibre of 20 mm or more (see autocannon).

Cannon also refers to a large, smooth-bored, muzzle-loading gun used before the advent of breech-loading, rifled guns firing explosive shells. Although a variety of such guns are commonly referred to as "cannon", the term specifically refers to a gun designed to fire a 42 lb shot as opposed to a "Demi-cannon" (32 lb), Culverin (18 lb) or Demi-culverin (9 lb).

When on board a warship a cannon is called a gun, while a cannonball is a roundshot.

Publié par Tolar à 11:45:19 dans Metal MMaxi | Commentaires (0) | Permaliens

metal | 21 mars 2007

In chemistry, a metal (Greek: Metallon) is an element that readily loses electrons to form positive ions (cations) and has metallic bonds between metal atoms. Metals form ionic bonds with non-metals. Metals are sometimes described as a lattice of positive ions surrounded by a cloud of delocalized electrons. The metals are one of the three groups of elements as distinguished by their ionization and bonding properties, along with the metalloids and nonmetals. On the periodic table, a diagonal line drawn from boron (B) to polonium (Po) separates the metals from the nonmetals. Most elements on this line are metalloids, sometimes called semi-metals; elements to the lower left are metals; elements to the upper right are nonmetals.

A modern definition of metals is that they have overlapping conduction bands and valence bands in their electronic structure. This definition opens up the category for metallic polymers and other organic metals, which have been made by researchers and employed in high-tech devices. These synthetic materials often have the characteristic silvery-grey reflectiveness (luster) of elemental metals.

The traditional definition focuses on the bulk properties of metals. They tend to be lustrous, ductile, malleable, and good conductors of electricity, while nonmetals are generally brittle (if solid), lack luster, and are insulators.

Publié par Tolar à 02:05:13 dans Metal MMaxi | Commentaires (0) | Permaliens

metal | 21 mars 2007

Publié par Tolar à 01:50:58 dans Metal MMaxi | Commentaires (0) | Permaliens

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