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Hardness of fine silver vs 22KY gold


#1

A question for the experienced metal workers out there. Which is
harder… fine silver or 22kt yellow gold? Or is the difference
negligible?

Thanks very much,

Joseph Bloyd
Bloomington, IN (Absolutely beautiful day!)


#2

It depends on the 22k alloy and whether it is work hardened, or
annealed etc but in general they are very similar. 22k annealed is 52
HV and sterling is 56-68 HV

Jim

James Binnion
James Binnion Metal Arts


#3

Jim

It seems to me that I saw a 24K (I think 24K US, which allowed some
small percent adulterant) gold that was tauted as being as hard as
conventional 18k. They added a low molecular weight element (Ca?) in
small percent by weight - the “k” thing, but a large percent by
molecule. Gold has a mass of about 197 (density of 19.3), Ca is about
40, Li is 3 with a density of about 1/2. Now while there is the
concern of intermetalics vs alloys (like purple, brittle AlxAu), the
folks pushing the 24k hard gold said there was no problem there.

Marlin, in hot today, cold tomorrow, Denver


#4
It seems to me that I saw a 24K (I think 24K US, which allowed
some small percent adulterant) gold that was tauted as being as
hard as conventional 18k. They added a low molecular weight element
(Ca?) in small percent by weight - the "k" thing, but a large
percent by molecule. Gold has a mass of about 197 (density of
19.3), Ca is about 40, Li is 3 with a density of about 1/2. Now
while there is the concern of intermetalics vs alloys (like purple,
brittle AlxAu), the folks pushing the 24k hard gold said there was
no problem there. 

Yes the technique is called micro-alloying. They add calcium and
gadolinium in a very tiny amount that would really almost would
qualify as an impurity rather than an alloy. In the case of the
"Pure Gold" alloy it is.9985 gold with the balance being the Ca and
Gd. When heat treated it would indeed reach hardness equivalent of a
typical 18k yellow. It is not an intermetallic but rather the Ca and
Gd act to “pin” the crystals in the gold matrix making it difficult
for them to move i.e. it is harder.

James Binnion
James Binnion Metal Arts