I once read on a web page I can no longer find that corundum is a covalent network. I'm guessing that's because despite the fact that the electronegativity difference between aluminum and oxygen is more than 1.7, corundum has exactly 2 valence electrons per bond so its valence orbitals hybridize into one orbital for each bond each of which is filled with 2 electrons making the substance really strong like a covalent network. Since it's a covalent network, if you replace each aluminum atom with a silicon atoms, would you have excess electrons some of which random walk to the surface atoms filling their outer shells and making nothing adhere very strongly to the surface?

There could be so many practical applications for it when it's etched nanosmooth. According to this article, diamond has high friction with itself in an ultra high vacuum and according to this question, super smooth surfaces have high friction with each other so I'm guessing that because of diamond's strong adhesion to itself from forming bonds between the surfaces, even when the normal force is tiny, the force of friction per area between the surfaces is almost as high or higher than the sheer modulus of diamond so the two diamond surfaces undergo the stick-slip phenomenon contributing to wearing out.

On the other hand, when you have 2 smooth spheres of corundum with some of its aluminum atoms replaced with silicon atoms sliding against each other even in an ultra high vacuum, the force of friction between them per area of contact will be much smaller than the shear modulus of the material so they should slide smoothly and not wear out. Also, a nanosmooth frying pan made of that material would be so revolutionary. It would not chemically degrade over time. All sorts of food would have so little adhesion with it. Maybe soft solids like squash though won't roll off because they have some adhesion to it and lack the ability to flow like a liquid and roll off and would have to be rinsed off. We could make tongs out of the exact same substance for those pans and have the food not stick to the tongs either and the tongs would not scratch the pan because the pan is made of such a hard material and they're both smooth and the tongs would not undergo the stick-slip phenomenon with the pan. Also, according to the Wikipedia article Fracture mechanics, brittle materials are weak because they have surface cracks and it takes a smaller amount of tension to magnify the tension to the breaking point at the tip of the crack and the longer the crack is, the less tension it takes to crack the material but if it's etched nanosmooth, its strength will probably be a significant fraction of its sheer modulus but according to this answer, the strength a material needs in order to not break on collision varies as its sheer modulus to the power of $\frac{4}{5}$ so it should totally resist breaking from colliding as long as it doesn't hit something rough in the collision like a rock and get scratched. Also, because it's so nonstick, it could be etched smooth and when it's pulled out of the etching liquid, the liquid will not cling to it and evaporate redepositing the material it dissolved away as a rough surface so it will remain nanosmooth after it's etched.

  • $\begingroup$ seems too broad and speculative a topic for this type forum. $\endgroup$
    – agentp
    May 7, 2018 at 15:57
  • $\begingroup$ Ceramic coating comes to mind... $\endgroup$
    – Solar Mike
    May 7, 2018 at 17:20
  • $\begingroup$ Speculative questions like this are not a good fit for the site. Closing as too broad. $\endgroup$
    – user16
    May 7, 2018 at 23:19
  • $\begingroup$ I suppose this question could be narrowed down to "Can corundum be made hard, slick, nonstick, and nondegredable that way?" but I already asked a similar question at chemistry.stackexchange.com/questions/91540/…. I originally posted that question on this site then they suggested I post it there. I originally posted this question on Physics Stack Exchange then they suggested that I post it here. Maybe this question is suitable for Worldbuilding Stack Exchange. $\endgroup$
    – Timothy
    May 9, 2018 at 17:09
  • $\begingroup$ I think that using math and the laws of quantum mechanics, it's possible to figure out what substance will have that property and how to produce it if such a substance is possible. $\endgroup$
    – Timothy
    May 11, 2018 at 16:39