B Matter and Friction: Adhesion, Deformation & Hydraulic Press

[mark2142]

Friction happens because of adhesion between high points of the pertubrances of the two surfaces. The pertubrances deform. More the force between surfaces more deformation. Is the deformation elastic or inelastic? Will the surface of one body become smoother if pressed with hydraulic press?

 

[jack action]

Friction happens because of adhesion between high points of the pertubrances of the two surfaces

... and intermolecular interactions (for example Van der Waals forces)

Is the deformation elastic or inelastic?

It will most likely depend on the material type and roughness (shape of the protuberances).

Will the surface of one body become smoother if pressed with hydraulic press?

One can imagine that the hydraulic press cannot make a surface smoother than its own surface.

Even assuming a high smoothness of the press surface, it might break some peaks, but at a certain point, the deformation might be only elastic. If you add force to a point of plastic deformation, the whole part will probably break/deform as well.

 

[mark2142]

... and intermolecular interactions (for example Van der Waals forces)

It will most likely depend on the material type and roughness (shape of the pertubrances).

One can imagine that the hydraulic press cannot make a surface smoother than its own surface.

Even assuming a high smoothness of the press surface, it might break some peaks, but at a certain point, the deformation might be only elastic. If you add force to a point of plastic deformation, the whole part will probably break/deform as well.

Like rubber vs steel. I guess what you are saying is Steel pertubrances too get deformed elastically to a certain point but that would require large hydraulic force. Got it!
Do pertubrances deform elastically while sitting on surfaces , without any force on them?

 

[jack action]

Do pertubrances deform elastically while sitting on surfaces , without any force on them?

How would they deform if there is no force acting on them?

 

[Baluncore]

Friction happens because of adhesion between high points of the pertubrances of the two surfaces. The pertubrances deform.

"pertubrances"? I think you meant "protuberances".
But a protuberance is usually something that protrudes from a different thing.
When discussing tribology, the term "asperity" is used to describe a high point on a surface.

 

[mark2142]

How would they deform if there is no force acting on them?

I meant no force other than mg.

 

[PeroK]

Do pertubrances deform elastically while sitting on surfaces , without any force on them?

Where's the mystery here? Just look at macroscopic objects. If you stand on something it could deform temporarily and then return to its former shape (e.g. a door mat); or, it could remain deformed (e.g. a gravel path).

 

[mark2142]

Thank you all.

 

[Bystander]

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