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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.

Timothy
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  • seems too broad and speculative a topic for this type forum. – agentp May 07 '18 at 15:57
  • Ceramic coating comes to mind... – Solar Mike May 07 '18 at 17:20
  • Speculative questions like this are not a good fit for the site. Closing as too broad. –  May 07 '18 at 23:19
  • 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 https://chemistry.stackexchange.com/questions/91540/can-diamond-be-made-to-have-low-friction-in-an-ultra-high-vacuum-by-replacing-so. 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. – Timothy May 09 '18 at 17:09
  • 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. – Timothy May 11 '18 at 16:39
  • I made a major edit to this question. I first asked https://physics.stackexchange.com/questions/409553/does-the-force-of-kinetic-friction-per-area-really-vary-linearly-with-the-normal and was going to wait for an answer to it before I edited this question to use the result of that answer but I never got one so I edited it to discuss my speculation of how friction between smooth surfaces works. – Timothy Jun 04 '18 at 03:20
  • Maybe if this question is not suitable for this site, it's no problem as long https://chemistry.stackexchange.com/questions/91540/can-diamond-be-made-to-have-low-friction-in-an-ultra-high-vacuum-by-replacing-so is still suitable for the site it's on. Once that question gets a good answer, it will be easy for researchers to figure out how to apply the possibility of such a revolutionary substance to the real world except maybe it's not getting much attention because engineers who would have recognized it as a good question for engineering and answered it won't find it on a different site. – Timothy Jun 04 '18 at 18:20
  • My question was focused. It's just a short simple question. The rest was explaining why the question might be useful. Do you think engineers can figure out the applications of that substance themselves so I don't need to add them. However, I still think it's worth adding them so that free content will be available for them in this question and nobody can be a patent troll for the applications such as a pan. I believe nonprofit organizations could start all over from scratch and be like "Screw it, we don't need to engage with for profit companies. We will start all over from scratch and figure – Timothy Feb 29 '20 at 19:01
  • out this stuff ourselves." I want to make the applications available to such nonprofit organizations without people being a troll and stopping the nonprofit organizations from using those ideas by being a patent troll for them. – Timothy Feb 29 '20 at 19:03
  • It may just be too hard for me to figure out how to make this question really good because I have so little knowledge and experience and am not an engineer. I would love it if somebody else asked another better question based on this question linking it just like Tommi did when they asked the question https://matheducators.stackexchange.com/questions/15475/is-the-education-system-in-finland-particularly-good. – Timothy Feb 29 '20 at 19:08
  • @agentp What are your thought on the comments I just wrote earlier today? – Timothy Mar 01 '20 at 03:11
  • I believe that once on Physics Stack Exchange, I asked a question whether diamond could be made nonstick by replacing some of its carbon atoms with nitrogen atoms or something like that. Then they suggested I ask it on Chemistry Stack Exchange so I did. It lasted there a really long time but eventually got deleted. I think that in theory if we had enough researchers with the right technique who are good at answering questions, Chemistry Stack Exchange would be the best website for that question. Maybe here is useful to to reveal how once such a substance gets created, it could be useful for so – Timothy Jul 01 '20 at 02:17
  • many applications. Maybe it is better to get an answer to this one first then ask about the possibility of creating one in the first place on Chemistry Stack Exchange so that they will then see that such an idea is so useful. – Timothy Jul 01 '20 at 02:18
  • I don't always think of every possible idea there is to think of because it's a quite advanced thing to do but now I'm thinking it would have been better to edit this question into the question at https://engineering.stackexchange.com/questions/36484/could-yellow-lab-grown-diamond-be-used-as-a-space-lubricant instead of asking it as a separate question. If that questions gets a lot of attention and then a question gets asked on Chemistry Stack Exchange confirming the underlying assumption and then it becomes obvious that that idea is being used, I might edit this question to be specifically – Timothy Jul 01 '20 at 14:10
  • about nonstick corundum. We could produce nonstick corondum burners. – Timothy Jul 01 '20 at 14:12
  • It's okay. You can keep this question closed for ever and not worry about it anymore. I finally got a good enough substitute for it with my questions https://mattermodeling.stackexchange.com/questions/4047/can-replacing-some-of-the-atoms-in-a-covalent-network-with-that-of-the-element-o and https://mattermodeling.stackexchange.com/questions/4047/can-replacing-some-of-the-atoms-in-a-covalent-network-with-that-of-the-element-o where they are well received. I know I just added more to the question about corundum being a covalent network having applications after that question already – Timothy Jan 05 '21 at 21:15
  • got the upvote. – Timothy Jan 05 '21 at 21:15

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