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Questions on making Copper-Silver-Zinc alloy
retro -
Tuesday, December 9, 2008 - 4:23pm
alloy | copper | silver | zinc Hi Everybody, My first post here, a question: I'd like to make an alloy of 80% Copper, 10% Silver and 10% Zinc, to be poured into lost-wax molds (plaster/sand). Copper and silver have reasonably close melting points (Cu 1981F and Ag 1762F), but Zn has a BOILING point of 1664F, meaning it could boil off before the other two melted. Could start with an available base alloy of 95% Cu / 5% Zn, and the pure silver, then add the remaining zinc and mix the alloy just before pouring. Does anyone here know what the melting point of 95Cu/5Zn would be? and would the Zn still boil out of the alloy as readily as pure Zn would? Will the mixing be likely to give problems? Does anyone have an idea what the casting behaviour of the 80:10:10 alloy will be? Thanks for any input. P.s., and yes i know about the dangers of inhaling Zn fumes. |
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ArtMetal
Generally, one melts the
Generally, one melts the lower melting point material first, then dissolves the higher melting point materials in that. I don't know how well that would work with zinc, which is notorious for boiling off. Perhaps if done in an induction furnace in an inert atmosphere you'd have better luck.
As for atributes, it should be a brassy yellow color, with good hardness and ductility, and a waste of the 10% silver you're putting into it. That's just my opinion, but I see no good reason to add a precious metal to an otherwise ordinary copper alloy, when it will offer no benefits in a cast product. Save the silver for where it is needed for higher ductility, greater thermal conduction, etc. You're casting a hunk of brass, basically, so stick with brass and avoid all the headaches and expense of concocting an unknown alloy.
Others here may differ with my opinion, naturally. There are several people here who have much more experience than I with casting, and almost anyone has more experience than I with concocting alloys.