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Gold on Titanium


#1

How to overlay gold onto titanium?

I am making wedding rings for my fiance and me, and the design
we converged on is a titanium frame with ridges at the sides, and
22-24k gold in the trough, with a gentle rounding up in the
center of the gold.

I am having a machinist lathe the Ti parts to my drawings, but
now I have to figure out how to get the gold into the trough.
The suggestions I have heard are:

(1) Casting: make a plaster mold with the Ti part lying flat,
and pour the Au in through a small hole. --> that seems difficult
for me, but if it’s the best way, the I can pay someone to do it.

(2) Compression: start with an oversized gold band and sqeeze it
in from all sides into the Ti trough. --> possible rattle when
done due to “spring back” effect of non-infinite maleability??

(3) Soldering: Wrap a gold band around the Ti trough, and solder
it. --> The only issue I have with that (other than all I know
how to solder is Silver) is that, while Ti does have a much
higher melting point than Gold (1660 vs. 1064 deg.C), Ti,
according to the Handbook of Chemistry and Physics (CRC Press):

“…combines with oxygen at red heat…” and also:

“…is dimorphic. The hexagonal [alpha] form changes to the
cubic [beta] form very slowly at about 880 deg. C.”

Perhaps the cubic form doesn’t look or act much differently, or
the change is really very, very slow, so that the dimorphism
aspect is not a concern – but what about the oxygen issue?
Would the soldering have to be done in an innert atmosphere? Or
is a reducing flame sufficient?

Any responses to these questions would be most welcome
(especially in light of the rapidly approaching wedding date!!)

-Joe Betts


#2

My suggestion for this band would be to have the Ti band machined
with a lip on one side and a second lip made as a separate piece
for the second side. The gold band would slide over the tube shape
to the lip on the first piece, then the second lip would slide on,
and the piece would be hammered into place by flaring the Ti tube.

I make something similar using niobium, see the image on the
Orchid gallery for reference. My band uses a niobium core and a
gold tube with two rims soldered on.

Rick Hamilton
Richard D. Hamilton
Martha’s Vineyard
USA
Fabricated 14k, 18k, and platinum Jewelry
wax carving, modelmaking, jewelry photography

http://www.rick-hamilton.com


#3

Reducing atmoshere is not enough, Must be inert, so of the 3
methods that you described only the second one has possibilty. But
instead of compression I would make sure the ridges on the titanium
band are not to tall say .5mm or so. Put the titanium band on a
mandrel which is relatively cold then heat your gold band to a
cherry red carefully and very quickly slide this ring over the
titanium band and let cool. The gold band will contract over the
titanium band and you will not move it. The key here is the ridges
cannot be to tall gold will expand but there are limits. There
also could be colorization of the titanium due the heat. Why
titanium???


#4

Do you want the titanium to be a color other than gray? If so you
will not want to use any heat process.

Mailyn Smith
Midwest USA


#5

Joe, We make a style of ring that I think can help you and they are
made with a lathe. It is basically a piece of tubing and two discs
that look like washers with their inside diameter being equal to
the outside dia. of the tubing. The i.d. of this tube should be the
finger size measurement. These parts would be Ti in your case. The
gold part would be a band with a inside dia. larger than the o.d.
of the tube. Take this tube and first put the gold band on it, then
the discs one on each side of it. The tube should be a little
longer than the thickness of the other three pieces so that you
can flare or rivet this tubing to hold the whole thing together.
You burnish the edge of this tube and it flares, thereby holding
the washer looking discs in place. Actually when I make these I
only have three pieces instead of four as above. One of my pieces
is a combination of the tube and one disc so that I only have to
flare and burnish one side of the ring. Think about those rings
that are lapis that are solid and cored out with a gold tube
through them and gold sides, and “how do they make them?” Regards-
Ricky Low-Houston (as in HOUSTON,WE HAVE A PROBLEM)


#6

Dear Joe,

Casting gold around, or into Ti works very well.

Form wax into the area where you want the gold to be, sprue it
laying flat with 2-3 sprues, and have it cast.

You might want to make the wax a bit higher than finish size to
allow for finishing.

The Ti might turn a darker gray color, but it survives quite well.

If you apply a torch to the Ti, as in soldering, it will heat
color the Ti. This may or may not be the effect you want.

good luck!