Tungsten carbide and tin solder 1

[7330]

Hi all,

I bought a Tungsten-carbide ring which has turned out to be too large... I thought of making the inner diameter of the ring smaller by soldering some tin in a thin layer onto the inside of the Tungsten-carbide ring.

I know Tungsten carbide would not melt anywhere near the melting temp. of tin, but would it even stay on ?

Has anyone here try something like this or at least has theoretical knowledge of possible problems ?

I really really don't want to end up loosing the ring....

Thanks

(Eng. Applied Physics)

 

[ornerynorsk]

Never tried tin solder, but I do know that brazing and silver solder both work quite well.

 

[1gibson]

Press fit a thin ring of something on ID. If you find a good hardware store, you can probably get small aluminum pipe. If it fits as-is, great. If not, get oversized and chop out 10* out of the 360* Solder the ends and file rough edges.


Or try casting a thin layer of epoxy on the ID, not sure how well it will adhere. Set ring flat, put some sort of core in the middle (sharpie, marker, dowel, use mold release or wrapped in tape sticky side out so it will release). Then fill.

 

[tomwalz]

The two major problems with sticking braze alloy to the carbide are contaminants, such as carbon and no oxides on the surface of the carbide, as well as ordinary oils and greases.

If you thoroughly clean the tungsten carbide with a detergent, dish soap, oven cleaner or similar and then very lightly rough up the surface of the tungsten carbide it will braze well.

I have been brazing carbide for 30 years but never tried to solder it. If you get the surface rough enough you can get the solder to adhere by physical attraction. You are not going to get it hot enough to create intermetallic bonds which, is where brazing gets its real strength.

Please be very careful how you handle the ring. Our e-commerce manager’s husband wore his carbide ring through a full tour in Iraq with no problems. He got back to the states and was going to order a pizza. When he reached for the phone book, his ring slipped off, hit the floor and broke in three pieces.

Some carbide is extremely tough while other is extremely fragile.


Thomas J. Walz
Carbide Processors, Inc.

http://www.carbideprocessors.com

Good engineering starts with a Grainger Catalog.

 

[jim07601]

Soldering is very difficult. They do make silver brazes which can be applied using a torch. If you can get by, you might just try an epoxy.

 

[7330]

Thanks all

The only gear I have in my lab is a simple soldering tool, silver melting temp is around 960 C, which is way too high for it...

I noticed that the electronic-shell configuration of silver is very different to that of tin - so I wonder if the 2 metals, the tin and the tungsten will stick.

The epoxy idea is interesting - is this comfortable to use on a ring for daily wear ? and what epoxy would you recommend ?

(Eng. Applied Physics)

 

[7330]

I found a chapter of some guide about working Tungsten carbide (attached). See page 33 "low temperature soldering" do you think that might work on a ring... ?



(Eng. Applied Physics)

 

[7330]

@ tomwalz

That's a good one.... Sounds like a mechanically resistant material with a crystalline structure (the reason I chose it) - also the corresponding low thermal-expansion coefficient, this is why together with molybdenum it is used with quartz... It shatters rather than bend.

Youtube shows some demos on how to remove tungsten rings.... but I still chose to buy ours the larger size from between-sizes...

Mind - they are wedding rings, so I will be careful if needing to rework them

(Eng. Applied Physics)

 

[ornerynorsk]

Mind you, most silver solder alloys are worked at ~around~ 625C. Easily obtainable with a hobby torch or plumbers torch.

Is your local jeweler out of the question? Sounds like a good way to get the significant other ticked off :>)

 

[tomwalz]

The general carbide information looks pretty good. I would quibble with them all in a message on a on a couple points but nothing major.

There is another discussion on here where somebody wants to put a metal ring around the outside of a carbide rod. You might check that out. There's some good discussions there.

It's called heating a ring in machines and machining engineering.

I'm thinking that maybe you could have a stainless steel insert made, shrink it with dry ice, slip it in and let it warm up. If you had a very small lip on either side it should stay in place really well.

The lips would have to be very, very small so that the lip part of the ring ring could pass through the carbide ring.

You would want to be very careful to take into account the coefficients of expansion between carbide and the stainless steel. You wouldn't want the stainless steel to grow so much during assembly or during use that it would stress the carbide from the inside.

You might go talk to a jeweler and see what they recommend. It would be another source of information and may give you something that you'd want to do yourself.

I wasn't implying that you were not going to be careful. I just never know how much people understand about the properties of tungsten carbide. Quite often I run into somebody who thinks that, because it's hard, it is also tough.

Anyway, congratulations on being in love and happily married. It sounds like a really interesting project. If you think about it post to let us know how it came, please.

Tom

Thomas J. Walz
Carbide Processors, Inc.

http://www.carbideprocessors.com

Good engineering starts with a Grainger Catalog.

 

[swall]

What about a build up with electro plating? Mask the O.D. and plate to the build up you need. I am thinking nickel or copper plate.