Can I weld silver with a blow torch?

Could you just braze it?

Could you just braze it?

Thanks for the suggestion, but unfortunately I can't simply braze it. I should have mentioned that the entire assembly must consist of pure silver (for use in a chemistry experiment). As you know, brazing would introduce metals other than silver.

Yes you can. Ancient silversmiths did not blanket anything with inert gas. You may in fact do such with a pencil torch - flame adjusted.

How strong are you talking about that it is even an issue?

cr3

Yes you can. Ancient silversmiths did not blanket anything with inert gas. You may in fact do such with a pencil torch - flame adjusted.

How strong are you talking about that it is even an issue?

cr3

Glad to hear it (yes, I should have thought about the ancient silversmiths). The joint between the two pieces need only have enough strength to withstand gentle handling and the weight of the disk (a few grams). Even a very small contact point should suffice.

Though I know the size of what you're working with, I'm not quite sure what the end result is you want. To reach the temperatures you want you will need a oxyacetylene torch. I regularly work with 50% silver alloy that melts at about 1280°. If you merely wanted to join two pieces of metal this, produces a very strong joint.

The oxyacetylene torch will get hot enough to melt Silver, (I would be more concerned that I would end up with a molten pile than not being able to melt my material) the thickness of material that you're working with is more in the line of what a jeweler would work with than myself. If you decide that you can work with alloys there available at any HVAC supply house along with the flux necessary to use them.

PS. There are other torch's available.A turbo torch is one that would probably get hot enough . Still the oxyacetylene torch with a very small tip would probably be your best choice. It can reach temperatures of over 5000°F. You might want to check with a jeweler and asked them how they weld silver.

A turbo torch is one that would probably get hot enough . Still the oxyacetylene torch with a very small tip would probably be your best choice.

Thanks for these two suggestions. So far, it sounds like an oxyacetylene torch, a turbo torch, and a pencil torch will melt pure silver. Now I just need to educate myself about the latter options (or do they refer to the same equipment?). I obviously have little welding experience, but I promise to take the proper safety precautions. Or I could just pay a jeweler to do it for me.

I had no idea it a pencil torch could reach the temperatures you need, I would guess you're going to need about 1950° for flow. If the pencil torch will do it without moving too much air it would probably be your best bet.

I've never worked with anything as delicate as you are currently working with. If there is an extremely small tip available for oxyacetylene, it has the advantage of being able to produce a very high temperature without excessive gas flow.

To satisfy my curiosity I googled temperature pencil torch. TexasCharlie was right ,at least according to the ads penciled torches can reach this temperature. Now to go full circle here is the best link I found.
http://process-equipment.globalspec.com/Industrial-Directory/pencil_torch

To satisfy my curiosity I googled temperature pencil torch. TexasCharlie was right ,at least according to the ads penciled torches can reach this temperature. Now to go full circle here is the best link I found.

http://process-equipment.globalspec.com/Industrial-Directory/pencil_torch

Thanks, the links look on that page look very useful. The pencil torch seems like the best fit to my project: good with small weld points, hot enough (oxyacetylene is much hotter than needed), and inexpensive equipment. I appreciate the good advice from all of you CR4 members.

You know there is a place where you can mark 'good answer' ....uh hmm.

No matter the method you choose, please remember two things:

1) Use a heat sink - or you may well end up with a pool of molten silver, at least on the first few tries.

2) Use all proper personal protective equipment appropriately, and follow SAFE work procedures.

Oh, and let us know how this works out, OK?

you could blanket the disk and heat the wire to melting before the disk reaches melting point via a blow straw with the torch. but the best would heat both till molten, then let them cool. but heat damage is a big concern. it is just like jewelery making. or you can cast the whole, via lost wax. the purity of the silver will also be a factor in potential discoloration. just old school..

Silver has the greatest thermal conductivity of any metal, so this could get tricky. I think I need to focus the flame as much as possible on the contact point, and complete the weld as quickly as possible, so that I don't convert the parts into a pool of molten silver.

Hi,

all this will not work as the thicknesses are too different.

Either make the silver disk thicker or the wire thinner or make thinner only a short (5mm) length of the wire, flattening by some big hammer and anvil will do it best.

The thermal conductivity of the two parts should be equal, else one will melt down and the other stay too cold.

If you can get an electrolytic oxygen-hydrogen generator, enhanced by some added alkohol in a bubbler, this would do best. These are sold with ultrafine nozzles down to 0.1 mm. Some goldsmiths have these, so ask and let them do.

I would not try acetylene on any silver. Silver can form a high explosive - silver acetylide - if excess acetylene is existing. In a flame this will burn immediately so no problem but better to avoid.

RHABE

I have welded , soldered and melted silver for casting for ten years with no ill effects.

I'm not sure if I could flatten the 2 mm diameter silver wire enough to achieve the desired surface without also making it so thin that it becomes too delicate, but this would avoid the need for welding. Worth a try. And thanks for the warning about the possible formation of explosive silver acetylide.

If lacking in either confidence or suitable tools, a high-street jeweller that has a workshop attached may be able to carry out this task for a small fee, perhaps (just a thought)?

If lacking in either confidence or suitable tools, a high-street jeweller that has a workshop attached may be able to carry out this task for a small fee, perhaps (just a thought)?

Yes, I agree -- especially since I only need about a dozen of these wire-disk connections. A jeweler could probably finish them all in a few minutes. I imagine it would not cost much. On the other hand, I would miss out on the enjoyment of developing my construction skills.

good answer. It does take quite a bit of skill to weld different size pieces of silver together. I have done it. Joint preperation is the key. It the silver disk were fashioned with a little tail coming out say 4 or 5 mm then the piece of wire could be welded to the tail. Silver has some of the best heat transferrence propertities of any metal.

Start with an oversized piece and file it down til you have a tail weather you or a jeweler do it.

There are mini oxy acetetelyne torches that can do it. Perhaps a jeweler in your area can weld it for you. If you cannot do that, try making a spot welder using a battery. It will take some trial and error but a large 6v battery, for instance can provide a significant amount of current momentarily.

Can you drill 4 holes (2 on each piece) and then bind them together with silver wire?

Orpheuse

Can you drill 4 holes (2 on each piece) and then bind them together with silver wire?

Orpheuse

You suggest an elegantly simple answer. Sounds like a good idea except for one possible problem: I must maintain very good electrical contact between the silver wire and disk. And since I will expose the silver wire-disk assembly to a potentially corrosive solution, I fear that a non-conductive or semi-conductive film might form between the two parts. I need to perform electrochemical measurements of the disk's electrical conductivity after bonding a mono-layer of fatty acids to its surface.

Indian Silversmiths do this easily with a simple (mouth-blowning) blowpipe while advancing a finer silver wire into the melt pool.Heat source is a tiny Oil Lamp Wicker Flame.

Theoretically you can ALSO weld high conductivity Aluminium ,Magnesium with Forging Force applied while passing a 3X pulse current . Silver is just a little more!

3X here will be 3 times the current of low carbon steel(~500A/mm2.)

For your wire dia 2mm >area 3mm2 you will need a peak pulse current=~5000 Amp. This will be possible from a Capacitor- stored- to -calculated volts and discharged by a MOSFET or Thyristor switch through Primary of a Pulse transformer.

Secondary coil of Pulse Trans.: -1 terminal will clamp onto a forced- down upper 2mm dia Silver wire. Terminal 2 of secondary will be a hefty Copper electrode on whose pencil flat top of minimum 5mm dia will sit the 25mmdia silver disk 0.2 mm thick.

Only variable will then be Capacitor Charged DC top Volts.

Now on you will need to create your own KNOW-HOW

You can use diffusion welding.

This is effective at 100 to 200°C below melting point at pressures of 2 to 5N/mm² and takes 1 to 2 hours to have enough time for diffusion.

For silver, gold and platinum group metals air is suitable else protective or reducing atmosphere recommended.

The higher the temperature the faster, same with pressure and time.

We did it with gold and platinum alloys and it worked at first trial.

RHABE