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AndrewM

Fri Nov 18 2011, 08:39AM

Registered Member #49 Joined: Thu Feb 09 2006, 04:05AM
Location: Bigass Pile of Penguins
Posts: 362

When making small quantities of gold alloys in a crucible, will the metals mix naturally upon melting (like pouring water into alcohol or acetone) or does it require stirring to properly mix the alloy?

Inducktion

Fri Nov 18 2011, 05:23PM

Registered Member #3637 Joined: Fri Jan 21 2011, 11:07PM
Location: Buffalo, NY
Posts: 1068

As far as I know, gold does not oxidize, and shouldn't need mixing...but, I don't know too much about precious metals, and that's just a wild guess!

Conundrum

Fri Nov 18 2011, 10:24PM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4062

Gold might not, but the other metals will.

Best bet is to add some suitable flux to de-oxidise the alloy metals while melting, and melt it in an inert atmosphere.

AndrewM

Sat Nov 19 2011, 01:51AM

Registered Member #49 Joined: Thu Feb 09 2006, 04:05AM
Location: Bigass Pile of Penguins
Posts: 362

I'm trying to make some DIY white gold, which depending on the alloy is gold and palladium plus some combo of silver, copper, or zinc.

I don't believe palladium oxidizes, at least.

So thats the issue, then? - if it oxidizes I'll need to stir and skim, but if it doesn't then it'll probably alloy readily?

Conundrum

Sat Nov 19 2011, 08:35AM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4062

Interesting.
I have some here, if I can find it...

On an aside, does anyone know where to get small amounts of gold? I wanted to try doping Sn4In superconductors with Au nanoparticles to see what it does to the Tc and Jc

-A

Steve Conner

Sat Nov 19 2011, 01:20PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Yeah, I always wanted to try that too! Erm, wait, no I didn't.

Anyway I'm sure your local jeweller's shop would sell you a small piece of scrap gold. The trade price for the stuff is some tens of pounds per gram.

I guess the problem would be that you don't know if it's pure, but refining it is probably easy compared to making the room temperature superconductors!

Nicko

Sun Nov 20 2011, 11:30AM

Registered Member #1334 Joined: Tue Feb 19 2008, 04:37PM
Location: Nr. London, UK
Posts: 615

Getting pure (24 ct) gold is unlikely from a jeweller - they'll probably have 9, 14 or 18 etc. 24ct is bullion and unusual in the West.

I bought a quantity of 24ct Au from a gold mine & refiners in Borneo some years ago - people in that part of the world like 24ct as an investment, but buy it as jewellery, typically chain etc. - it's sold by weight - even the clasp etc. is 24ct. Much deeper yellow, and so soft you can easily mark it with a thumb nail - wears & marks easily, so pretty useless for day-to-day use.

Best bet is to buy a small bit of bullion, either as a small ingot or bullion coin (i.e. certified purity) and then to work with that.

Conundrum

Sun Nov 20 2011, 01:50PM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4062

Thanks!

Fe contamination is especially problematic..

Interesting thought, could a material that superconducts at room temperature actually exist in nature?
Would be cool to have "floating rocks" like on "Avatar" or "Journey to the Centre of the Earth 3-D"

-A

Ocean Waves

Tue Nov 22 2011, 02:34PM

Registered Member #4181 Joined: Thu Nov 03 2011, 02:39PM
Location:
Posts: 42

some gold alloys like sky blue and deep purple gold have to be created in an argon furnace, but you can make green gold and red in an electric kiln but i prefer to flood the kiln with hydrogen or propane just enough to deprive oxygen from the mix or use a borax flux ( 20 mule team from walmart in the laundry section)

many variations of these exist these are the basic............

green=79% gold 1%copper 1%iron %19 silver
red = 70% gold 30% copper
sky Blue= 75% gold 5% indium 20% iron
blue= 95% gold 5% iron
white= 50% gold 50% nickel
purple= 50% gold 50% aluminum (purple poison)

iron can be removed completely by adding silica to a borax flux this rapidly forms iron meta slilcate, which is also why you have to use a zrconia crucible or machined graphite when making blue gold

I have always wanted to make a quantity of purple poison, but have never had all the required equipment in one place at once at any given time......

though I might have made a quantity of blue gold electrolytically once when experimenting with potassium ferro cyanide solutions in lixivating gold, using a small electrolytic cell for recovery I was getting a nice light blue crystals with a bright luster plating out on a carbon cathode.......a bit of tweaking to the solution by adding a surfactant might have yielded a smooth bright finish

Conundrum

Sat Nov 26 2011, 08:02PM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4062

Heh, machined graphite.
Not a bad idea.
Just a thought, but would a homemade fire cement crucible work at all?

On an aside, can anyone confirm or deny the conspiracy theory that possessing any quantity of certain specific gold alloys can get you a visit from the MiB's?

Something to do with nuclear weapons but am not aware of the exact use.
Perhaps to do with the initiator, AFAIK polonium-beryllium but plated with this special gold alloy to alter the pulse generation to sharpen the "spike" so the yield goes up.
Without this particular trick the yield of a typical nuke is down in the 500T range instead of the high tens of kilotons.

I know that "FOGBANK" was to do with fusion devices, as it helped control the X-ray pulse that initiated the fusion (aka hydrogen bomb) reaction and was an aerogel doped with beryllium and some other elements which acted like an X-ray equivalent to a laser's Q-switch.
Obviously the specifics are not public but this is extrapolated from the few papers which are.

-A

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