Cold welding!

[tight fart]

I'd never heard of this before (and struggle to believe it)

If two pieces of the same type of metal touch in space, they will bond and be permanently stuck together

This amazing effect is called cold welding. It happens because the atoms of the individual pieces of metal have no way of knowing that they are different pieces of metal, so the lumps join together.

This wouldn't happen on Earth because there is air and water separating the pieces. The effect has a lot of implication for spacecraft construction and the future of metal-based construction in vacuums

[Mr Pointy]

Why don't any metals in a vacuum chamber on Earth weld themselves together then? We can make much higher vacuums than those that exist in space.

[CubanPete]

Yep, why you should always leave your micrometer or slip gauges separated.

There are other cold welding techniques, ultrasonic and friction stir.

[2fast748]

tight fart said:

I'd never heard of this before (and struggle to believe it)

If two pieces of the same type of metal touch in space, they will bond and be permanently stuck together

This amazing effect is called cold welding. It happens because the atoms of the individual pieces of metal have no way of knowing that they are different pieces of metal, so the lumps join together.

This wouldn't happen on Earth because there is air and water separating the pieces. The effect has a lot of implication for spacecraft construction and the future of metal-based construction in vacuums

I thought this was fairly common knowledge? Tools used in space have to have an ultra think plastic coating to prevent cold welding.

[take-good-care-of-the-forest-dewey]

You can recreate the effect with a bare alloy seat post into an alloy frame... Ask me how I know

OK... Some friction welding too.

[Beati Dogu]

^ is that what they call butt welding?

[ndtman]

[Nimby]

Mr Pointy said:

... We can make much higher vacuums than those that exist in space.

Apparently not.

This might also be of interest: ultra-flat gauge blocks "weld" together even in air.

[take-good-care-of-the-forest-dewey]

Beati Dogu said:

^ is that what they call butt welding?

[McGee_22]

Nimby said:

Apparently not.

This might also be of interest: ultra-flat gauge blocks "weld" together even in air.

Making a pair of gauge blocks was part of every Marine Naval Apprentices training programme... when they still had Artificers.

[Huff]

OP - its not true that it can;t happen on earth - Titanium, for a start, will 'diffusion-bond' when in contact and effect that accelerates with heat - its even used in some fabrication processes; and its also one reason it galls like a bd if used eg. as a fastener in steel without a suitable coating/lube.

I thought guage-block 'wringing' was van der waals forces rather than diffusion bonding as such.

[Brother D]

I think this is kinda cold welding with earth bound applications

https://www.popularmechanics.com/military/navy-shi...