Talk:Bronze

From Wikipedia, the free encyclopedia

This article indicates that Bronze does not oxidize, which, according to the Historical Preservation Technical Procedures index (http://w3.gsa.gov/web/p/hptp.nsf/035c614b995c0406852565d1006211b3/6c8c800d5618e023852565c50054b2c6?OpenDocument), is not true. The patina that bronze develops is part of the oxidization and sulphurization process--not a replacement of it.

Acoustic guitar strings and electrical components' contacts are often described to be plated with "phosphor bronze". Any information or references about this? --blades 00:05, May 16, 2004 (UTC)

Does this need to be in the 'metals' category? It's already in alloys which is a subcategory of metals. -David 04:50, Oct 21, 2004 (UTC)

Is there a difference between bronze being harder and more durable than stone or is the latter a consequence of the first? MarSch 13:15, 6 Apr 2005 (UTC)

Contents 1 Brass vs. Bronze 2 Bronze vs. Iron 3 Composition 4 English 5 Origins 6 Expanding slightly just before they set? 7 A list of civilizations 8 Etymology

[edit] Brass vs. Bronze

The brass article seems to imply that, while some brasses are called "bronze", this is incorrect:

Some types of brass are called bronzes, despite their high zinc content.

On the other hand, this article indicates that "bronze" is a general term for copper alloys, and therefore includes brass:

brass, a subset of the bronze alloys in which zinc is the principal additive

I am not qualified to judge which of these is correct, but they seem to contradict each other.

Similar comment posted on Talk:Brass.

— Nowhither 00:20, 25 August 2005 (UTC)

I guess its a wide/narrow use of the word. The narrow definition is bronze=Copper+tin+(impurities). The wide definition is of Copper+something. dic def Zeimusu | Talk page 13:18, 2005 August 25 (UTC)

[edit] Bronze vs. Iron

I thought bronze is weaker than iron. What causes this difference? 66.195.132.2 13:06, 18 October 2005 UTC

To make it easier for others to follow you, please sign your comments with four tildes: ~~~~ Thanks.

Bronze is stronger than simple iron, but weaker than carburized iron. In the ancient period, therefore, bronze was stronger but more expensive than iron. As ironworking techniques improved, iron took over bronze, being both cheaper and stronger. Also, unless I'm mistaken, bronze has a lower melting point than iron and is therefore easier to cast, but harder to forge due to its greater hardness. —Simetrical (talk) 20:47, 18 November 2005 (UTC)

Regarding:

Bronze was also stronger than iron, another common metal of the era,...

This does not sound right to me - to which era is the article refering? I guess that there might have been a period in the late bronze age when small amounts of iron were being used and this iron may been weak due to impurities etc. I would like see some cites for this. Bronze has a much lower melting point than iron and it was quite impossible for the ancients to cast iron. Bronze is far more maleable that iron and bronze artifacts sometimes have beaten details that could never have been achieved in iron. See Yetholm-type shields for example.

Regarding the statement:

As an example, Roman officers were equipped with bronze swords while foot soldiers had to make do with iron blades.

To what period of Roman history does that apply?

Another questionable statement:

Bronze also has very little metal-on-metal friction, which made it invaluable for the building of cannon where iron cannonballs would otherwise stick in the barrel.

Bronze is often used for bearings, but I don't think that has anything to do with cannons. Early cannons did not fire tight-fitting balls which were, in any case, often made of stone. If the above is true, why arn't modern guns which do have tigh-fitting ammunition, made of bronze? My understanding is that early cannons were made of bronze because of the adaptation of bell casting techniques were the only practical method available.

Methinks this article needs some work... Gaius Cornelius 01:08, 23 November 2005 (UTC).

This says that "Iron is not superior to bronze for tools. Wrought iron, the form first encountered by Near Eastern smelters, is roughly equivalent in hardness to annealed 10% tin bronze, and inferior to all cold-worked tin bronzes. It is only when carbon dissolves into the iron (carburization) and the artisan quenches the resulting steel that ferrous metals have a definite hardness advantage over bronze." No mention of when carburization was discovered, though, do you know? Partial carburization was certainly possible during early-mid Roman times, but I don't know at what point iron surpassed bronze in price or strength. —Simetrical (talk) 02:27, 23 November 2005 (UTC)

Well, when you take into account that the period where 90% of the tools were iron was in the 10th century BC, I think we can safely say that bronze was surpassed by iron in terms of cost at that point, and hardness equality would follow. This is long before even the beginnings of a Roman Senate, so I seriously doubt that Roman officers (Centurions or whathaveyou) were equipped with bronze weapons when the Romans did have access to steel, and used it in their swords. It is also my opinion (and only that) that (HC) steel is a superior sword material because once properly tempered it has good edge retention but is still nice and springy.

As far as cold-working bronze vs iron goes, I can safely assume that would create alot of stresses in the metal (it does so for iron or steel, anyway), making it very hard, yes, but very brittle too. That is not the sort of thing you want in a tool like a scratchplough or a nail. Instead, toughness is much preferred. Alej

[edit] Composition

This article does not contain the usual composition of bronze, which a quick google:define turns up as 60% copper to 40% tin. I'll pop this up.

80.2.26.219 20:29, 18 November 2005 (UTC)

That sounds like far too much tin. Anything around 10% tin would be considered a high-tin bronze. 62.239.24.22 13:16, 24 November 2005 (UTC)

That composition would be Speculum which was used for coin making in Roman times (in Gaul and Britain anyway) --Nomiro 11:25, 9 November 2006 (UTC)

40% is way too high. The (approx.) 23% tin of the bronze used in Indonesian gamelan and the similar tin content of bell metal are the highest tin contents in regular use, apart from speculum metal. In engineering applications, 18% tin is around the upper limit for a high-tin bronze. 40% tin is therefore not 'typical'. There is really too much variation among bronzes for any 'usual composition' or 'typical' figure to be given. And brasses and bronzes are two separate families of copper alloys. EEye 12:04, 27 March 2007 (UTC)

[edit] English

"Bronze" is English, but not that anciently. I've modified the statement.

[edit] Origins

The Bronze Age article states that bronze was developed by the Maykops (see Maykop culture). Is there a reason why this article states differently? --Brunnock 14:05, 2 February 2006 (UTC)

I am quite sure that the patina of bronze is formed by oxidation, so the statement "While bronze forms a patina, it does not oxidize" is incorrect. Will someone else confirm this?

Patination composition varies with the reacted elements and will determine the color of the patina. Exposure to chlorides leads to green, while sulpher compounds (such has "liver of sulpher") tend to brown. Patination is deliberately accellerated by heat. Colors range from matte sandstone yellow to deep blues, reds and various blacks, sometimes with the surface sheen enhanced by waxing for artwork displayed indoors. - Leonard G. 18:44, 31 December 2006 (UTC)

[edit] Expanding slightly just before they set?

"Common bronze alloys often have the unusual and very desirable property of expanding slightly just before they set, thus filling in the finest details of a mould"

I don't think this is true. Has anyone a source? As far as I know, liquid to solid shrinkage of about 5% occurs with copper and most of it's alloys. This can be offset by regulating the oxygen content which will allow microscopic bubbles to form, which will offset some of the shrinkage. But I don't think you can get it to expand....

--Nomiro 11:15, 9 November 2006 (UTC)

[edit] A list of civilizations

It would be good to list civilizations and their usage of bronze.--HalaTruth(ሀላካሕ) 08:25, 31 December 2006 (UTC)

[edit] Etymology

The etymology of "Britain" here given seems spurious - the cited page makes no mention, and the only other references I can find on the 'net (don't have any books handy) are mirrors of Wikipedia. Identical line in Brython, removing both. - Somnior 21:21, 30 January 2007 (UTC)