| Purpose |
-
Mix Alloy #860 with fine gold to obtain 10K
or 14K White Gold for sheet, plate, and wire fabrication.
-
Can also be used for investment casting if
desired.
|
| Melting |
-
#860 Alloy and fine gold should be melted
together in a clean crucible. Put the alloy in the bottom of the crucible
and the fine gold on top.
-
Initial melting temperature should be 1070°
C / 1958° F. Drop the temperature somewhat before pouring as
listed below.
-
Boric acid flux should be used to keep the
metal clean during the melting process. The molten metal should be mixed
well with a stirring rod before pouring to assure a good mix.
-
A neutral or reducing cover gas is very helpful
in melting white gold alloys.
|
Pouring Temperature
for Ingots |
-
1OK 1040°C / 1904°F.
-
14K 1010°C / 1850°F.
|
| Pouring |
-
Metal should be poured into a preheated, vertical
graphite, or lightly lubricated iron mold.
-
A steady even pouring motion should be used,
slowing down at the end of the pour to prevent shrinkage in the top of
the ingot.
-
Use a round rod mold for wire, and a 2 piece
L shaped mold for plate and sheet.
|
| Quenching |
-
Remove the ingot from the mold and allow to
air cool - don't quench. Nickel white gold rolling alloys will be
much softer if allowed to air cool after pouring and after annealing.
-
Soak ingot in a hot pickle solution to remove
surface oxides.
|
| Fabrication |
-
The metal ingot should be cleaned of all adhering
oxide or fluxes before rolling.
-
The ingot should be rolled or drawn to a 50%
reduction in size before annealing.
-
Too small of a reduction can cause ingot to
crack during anneal.
-
After annealing continue the reduction at
50% before annealing again. Clean the ingot after each anneal in hot pickle
solution.
-
Keep the rolls, dies, and metal clean to prevent
defects in the finished stock.
|
| Annealing |
-
Annealing temperature 732° C/1350°
F for 20 minutes.
-
DO NOT QUENCH INGOT, allow ingot to air
cool.
-
A boric acid fire coat should be applied before
annealing in an open atmosphere oven to protect the metal from heavy oxidation.
-
Clean the ingot in hot pickle solution to
remove surface oxidation after annealing.
-
Avoid over-annealing wire, plate or sheet
stock as this can cause excessive grain growth creating orange peel surface
or poor strength in finished goods.
|
| Re-Melting |
-
Use a 30% scrap to 70% fresh mix on nickel
white gold alloys.
-
White gold alloys have about 1/3 the re-usability
of yellow gold alloys.
|
| Investment Casting |
-
Pre-alloy #860 and Fine Gold and pour into
water to make shot.
-
White gold alloys have about 1/3 the re-usability
of yellow gold alloys.
|
| Pre-Alloying
Temperature |
|
| Casting Temperature |
-
10K 1040°C, 1904°
F.
-
14K 1000°C, 1832°
F.
|
|
Flask Temperature
|
-
Use somewhat hotter flask temperature.
|
| Quench Time |
-
8 to 12 Minutes for invested flasks.
|
