I'm just curious: what happens when you write on a piece of paper with a pencil? Does the graphite actually penetrate the paper, or is it just on the surface? Also, what kind of adhesion occurs between the two materials? Thanks for your time.
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Friction of drawing the graphite across the paper causes the graphite to shear in very thin flakes, which become attached to the paper fibers and perhaps embedded in the fibers or stick to the ceramic filler. The graphite particles are quire small.
They can be removed (erased) so they are at the surface with finer particles penetrating more deeply into pores in the paper surface.
The maybe some van der Waals forces at work, but the magnitude is probably small.