Ancient dagger found in Bulgaria

Azsoldier said:
An old broken knife....
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Probably broken intentionally to help keep it from walking out of the grave. The thing is priceless to us today; but, when they buried this guy it had been recently manufactured junk.

n2s
 
kronckew said:
'sharp enough to shave with' ??????
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It just goes to remind us that our language is very poor when it comes to discribing levels of sharp.

n2s
 
They did say it was gold and platinum mix, so it wouldn't have corroded any. Not sure how long the edge would hold up with use, but just sitting thee it should still be sharp. Maybe???
 
i was interested in how they'd managed to get an edge on a gold/platinum alloy blade in the 1st place, gold doesn't work harden like copper or bronze & stays soft, mebbe it's a very low gold/platinum bronze alloy?. mebbe more details will emerge, the little picture & one paragraph is not enough.
 
kronckew said:
i was interested in how they'd managed to get an edge on a gold/platinum alloy blade in the 1st place, gold doesn't work harden like copper or bronze & stays soft, mebbe it's a very low gold/platinum bronze alloy?
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I'd like to know more about what platinum does to gold in alloys as well. How much platinum is needed to really change things? This blade is actually broken- not the typical bending malleable nature of gold.

I did want to point out that pure gold does indeed work harden, and the various common alloys can get a lot harder than many folks seem to expect. One time when I was forging out a piece of 18 karat, as it work hardened it was leaving big dents in the face of my hammer and anvil!
 
DannyinJapan said:
chances are very good that all of us white folks were a part of this Thracian civilization....
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Danny, How do you know how white those Thracians were? :confused:
 
Id guess that its platinum powder in a gold matrix, that can be smelted at much lower tempratures & presumably would be more brittle as well.

If its brittle it would probably also take a sharp edge.

Spiral
 
alloys are an interesting subject, i'm of course not a materials engineer, just a mechanical one & thus more used to steel alloys, but i just did a little research, which of course is dangerous as i'm probably spouting nonsense.

appears that gold-platinum alloys have very variable melting points and need to be cooled quickly or can result in a hard and unfortuneatley brittle form.

can also be age-hardened by heating and soaking it for extended time. this is for alloys of 900 parts platinum to 100 parts gold, normal vickers hardness of 135*.... probably why this blade is broken, if it was hard enough to hold any kind of an edge, musta been quite brittle. the blade was probably not an alloy commonly in use today....

also, found out 18k gold alloy is generally harder than lower carat, so it's a myth that 9k gold is harder still, it's actually about half as hard, still harder than 24k stuff tho.. titanium can harden it at very low levels....

*-difficult to convert to rockwell C hardness but bronze is about 60-80 vickers & razor sharp bronze weapons were of course produced, roman razors are frequently bronze...
 
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