Making a brass alloy
Making a brass alloy
(OP)
Can someone tell me what the best way to melt copper and zinc together is?
Thanks in advance.
Thanks in advance.
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RE: Making a brass alloy
RE: Making a brass alloy
With the melting point of copper being 1083 and zinc having a boiling point of 907, I wanted to know the best way to melt the 2 together to form an alloy.
RE: Making a brass alloy
RE: Making a brass alloy
Tom
Thomas J. Walz
Carbide Processors, Inc.
www.carbideprocessors.com
RE: Making a brass alloy
There is no reason to fully melt the Cu first. You would be better off if you can melt a small amount of brass to start with. You will keep the melt temp lower and loose less metal.
Don't underestimate the Zn fumes. You don't want to be breathing this.
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RE: Making a brass alloy
Mike Halloran
Pembroke Pines, FL, USA
RE: Making a brass alloy
RE: Making a brass alloy
Starting materials should be small pieces & mixed to enable rapid alloying to lower the zinc activity & vaporization.
Preheat the melting pot or crucible (a gas flame works), load the charge, and cover with an inch or so of borax. Acts as a flux, holds the zinc vapor in, and is inexpensive.
w/o some premixing of the solid pieces and the use of flux, zinc losses are high:
"The appropriate amount of suitable copper alloy scrap is weighed and transferred into an electric furnace where it is melted at about 1,920°F (1,050°C). After adjusting for the amount of zinc in the scrap alloy, an appropriate amount of zinc is added after the copper melts. A small amount of additional zinc, about 50% of the total zinc* required, may be added to compensate for any zinc that vaporizes during the melting operation..."
http://www.madehow.com/Volume-6/Brass.html
*my highlighting. 50% loss is absurdly high.
For fluxing of copper & zinc, see
Molten Light Metal Processing: Part Two
http://www.key-to-metals.com/Article84.htm
Of course, you need a few foundry tools for stirring, skimming off flux and slag, etc.
RE: Making a brass alloy
My be a stupid question but I'll ask anyway, am I wasting my time by trying to melt the copper with a blow torch?
I have a small amount of copper scrap (very small pieces) and I want to melt the copper down but cannot afford a kiln/furnace and only have a propane blow torch and I have heated the copper in a metal dish for a good few minutes and it goes orange but no further.
RE: Making a brass alloy
What metal do you have that may be inert toward copper? Graphite or the cheaper clay-graphite may be better. Use a crucible with a lid to hold in heat & zinc vapor (along with the flux).
RE: Making a brass alloy
RE: Making a brass alloy
It takes some investment, and more heat than from a handheld propane burner, to melt copper alloys. The least expensive set-up:
Of course, need protective gear, etc. See http://www.webcom.com/sknkwrks/foundry.htm
And, what is the point of simply melting the alloy? To cast white hot liquid metal w/o proper equipment & experience may lead to the emergency room of the local hospital.
RE: Making a brass alloy
The picture looks remarkably like my own set-up, except I have a 12x12 hard firebrick tile as a hearth/base, my burner is driven by a small blower, and the insulating firebrick box is wrapped in a batt of mineral fibre insulation.
The trick is to have a proper crucible and a safe means to lift it out of the box- don't bother even trying to do this in a "metal dish".
The borax flux is essential not only to keep the zinc losses down but also to flux (dissolve) the oxides from the scrap you're melting. It's a bit tricky to skim the borax off the melt prior to pouring- still figuring that one out.
RE: Making a brass alloy
My boss has given me a plaster paris (gypsum) mould and said the brass (around 850oc) would be able to cast in that but I am a bit skeptical.
RE: Making a brass alloy
Foundries have special plaster mixes that are more permeable than plaster-of-Paris; this lets air escape from the mold better during filling.
RE: Making a brass alloy
Any presence of moisture in the mold can be disastrous.
" All that is necessary for triumph of evil is that good men do nothing".
Edmund Burke
RE: Making a brass alloy
I do all my castings in sand- roughly 20:3 mix of silica sand and bentonine (or ground cat litter), moistened gently to the point where a clump of sand squeezed in the hand can be broken cleanly in half without crumbling.