Cold Welding in a Vacuum

Blacksmiths have been forging metals together with hammers for centuries.

Japanese sword makers comes to mind...

I'm talking about a light force, like pushing them together....no forge, no hammer, just a push...

Like fusion... sounds like an Einstein theory of cold fusion.

Vacuum welding seems like more of a nuisance than useful. There are a lot of ways to intentionally weld metals together. Since vacuum welding is a natural process, I would think the quality of the welds would be hard to control.

Well the vacuum only serves one purpose, to eliminate the oxygen that forms the oxides that prevents similar metals from joining with just a little pressure....so if there was a spray on material that would accomplish this, then the vacuum would no longer be necessary....with a perfectly smooth, or somewhat so, smooth surface the joining would be nearly complete....much better than being welded just around the perimeter, the two pieces would become as one, no stress area....the trick is to formulate a spray that was compatible with the type metal that was being welded, and also could block the oxide formation that prevents this process from taking place...sort of a liquid metal that matched the molecular qualities of that particular metal, but was immune to oxidation...maybe a two part process, with the first spray-on cleaning and deoxidizing the metal surfaces, perhaps acting as a primer...then joining by possible sonic vibration while gentle pressure is applied....

You're putting something else besides air between the two pieces. So the pieces need to stick to that something. I think that's how glue works.

https://newatlas.com/mesoglue-metal-glue/41292/

That's very interesting, like instant solder. I've never liked soldering semiconductor devices for fear of overheating, and this was back in the day of dip packages.

I'm wondering about the price and whether the connection can be undone.

https://newatlas.com/mesoglue-metal-glue/41292/

https://www.edn.com/mesoglue-will-not-replace-solder/

https://www.evgroup.com/technologies/metal-diffusion-bonding/#:~:text=Metal%20diffusion%20bonding%2C%20also%20known,to%20form%20the%20bond%20interface.

https://opentextbc.ca/chemistry/chapter/11-1-the-dissolution-process/

That's exactly how the cyanoacrylate adhesives work.

I've experienced and dealt with cold welding in UHV chambers.

Applying any fluid between the smooth similar metals may block oxygen to prevent oxidation but it will also add a lubricating layer between the metals and prevent cold welding unless enough pressure is applied to squeeze out the fluid.

It is also believed by some that the root of most smooth bearing experiences of stiction is actually a tiny cold weld. When cold welds happen the actual two metals bonding as one weld area is rarely known. Thus even when polished metal surface areas are in contact with each other in a vacuum, predicting how much force will be needed to break a cold weld weld is impossible to know. Hot welding liquifies the metals so the entire worked upon area (when performed correctly) becomes one metal.