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Are there any processes yet that can yield a blade for a kitchen knife? 8-12 inch/20-30 cm, for an affordable price? Due to the high hardness it would be possib

by namibj 8y ago

Are there any processes yet that can yield a blade for a kitchen knife? 8-12 inch/20-30 cm, for an affordable price? Due to the high hardness it would be possible to cut the edge very shallow, possibly even with a slight undercut near the blade. It could retain razor sharpness for days, possibly longer. This enables much sharper knifes at tool life suitable for normal usage. I'd even settle for a carbide blade, which, while I know one company made one [0], I am unable to find a source for such a knife. [0]: This is a publicity stunt, but from what I can tell, this does not need to be faked: https://www.youtube.com/watch?v=IcyluvvEfQo https://www.youtube.com/watch?v=IcyluvvEfQo

s0rce 8y ago
It would still be very brittle.
iamgopal 8y ago
You coat carbon steel with diamond nano particle to give it nice hardness. They already do that on machine tool cutters. Same process also used for TiN or similar hard coating. I think unfavorable production price being the reason for it not being consumer product.
MisterTea 8y ago
You trade strength for hardness. As hardness increases its ductility decreases becoming more brittle. That super hard blade will shatter like glass if dropped on a hard floor or snap if too much lateral force is applied. Same reason ceramic knives aren't more popular. I grew up in a machine shop and those little super hard carbide cutter inserts are surprisingly easy to crack or break if you feed too fast. I remember getting cocky on the lathe trying to take a big cut off a 2 inch bar of mild steel; came in too fast and the lip on the bar from hand cutting on the bandsaw caught the edge of the little $25 carbide insert and shattered it like glass.
- namibj 8y ago
  The thing is, the very edge, i.e., the first about 5 micrometers, possibly up to about 20 micrometers, need to be strong enough. There are measurements on [0] that show how one can get a steel edge about 50 nm wide, and the same source claims 100nm to be necessary for cutting a free-hanging mustache hair. That "a triangular bevel with a 16 degree included angle is typically too weak to survive shaving a normal-to-heavy beard" [1] leads me to think that this coating is unlikely to reach the required thinness of the edge. You can buy utility knifes with such coatings, or at least I stumbled upon someone comparing different coatings on utility knifes, including diamond nano particles. Judging by the low life of such a sharp blade which 'just' cuts hairs, I don't think a coating will reach the target. And yes, the edge will be prone to shattering, but I never said I'd want to be careless with the knife, or never have to care for it. I just don't want to sharpen it more than once a week. If you look, the video I posted shows them hitting a rope, I assume nylon fibers, which certainly isn't that soft, and instead of shattering it results in an almost complete cut. For your carbide cutter you do have to remember that neither your cutter not the lip/bar was particularly likely to give in much. As long as it won't break if I cut a fish and hit a bone, it's not too brittle. I might need a softer cutting mat, but considering the (lack of) force I'd need, the softness shouldn't be much an an issue. And the cubic zirconia knifes I have do experience significant wear, judging by how quickly they lost their reasonably-sharp state and are no longer superior to a regularly sharpened (cheap) steel knife. One would probably need a hard-ish backing, e.g. maybe something like an edge-hardened steel blade, but with the thermal expansion coefficient matched to the diamond edge/insert. [0]: https://scienceofsharp.wordpress.com/2014/01/25/quantifying-sharp/ https://scienceofsharp.wordpress.com/2014/01/25/quantifying-... [1]: https://scienceofsharp.wordpress.com/2015/03/24/sharp-and-keen-part-2/ https://scienceofsharp.wordpress.com/2015/03/24/sharp-and-ke...

by namibj 8y ago

s0rce 8y ago

It would still be very brittle.

iamgopal 8y ago

You coat carbon steel with diamond nano particle to give it nice hardness. They already do that on machine tool cutters. Same process also used for TiN or similar hard coating. I think unfavorable production price being the reason for it not being consumer product.

MisterTea 8y ago

You trade strength for hardness. As hardness increases its ductility decreases becoming more brittle. That super hard blade will shatter like glass if dropped on a hard floor or snap if too much lateral force is applied. Same reason ceramic knives aren't more popular. I grew up in a machine shop and those little super hard carbide cutter inserts are surprisingly easy to crack or break if you feed too fast. I remember getting cocky on the lathe trying to take a big cut off a 2 inch bar of mild steel; came in too fast and the lip on the bar from hand cutting on the bandsaw caught the edge of the little $25 carbide insert and shattered it like glass.

namibj 8y ago
The thing is, the very edge, i.e., the first about 5 micrometers, possibly up to about 20 micrometers, need to be strong enough. There are measurements on [0] that show how one can get a steel edge about 50 nm wide, and the same source claims 100nm to be necessary for cutting a free-hanging mustache hair. That "a triangular bevel with a 16 degree included angle is typically too weak to survive shaving a normal-to-heavy beard" [1] leads me to think that this coating is unlikely to reach the required thinness of the edge. You can buy utility knifes with such coatings, or at least I stumbled upon someone comparing different coatings on utility knifes, including diamond nano particles. Judging by the low life of such a sharp blade which 'just' cuts hairs, I don't think a coating will reach the target. And yes, the edge will be prone to shattering, but I never said I'd want to be careless with the knife, or never have to care for it. I just don't want to sharpen it more than once a week. If you look, the video I posted shows them hitting a rope, I assume nylon fibers, which certainly isn't that soft, and instead of shattering it results in an almost complete cut. For your carbide cutter you do have to remember that neither your cutter not the lip/bar was particularly likely to give in much. As long as it won't break if I cut a fish and hit a bone, it's not too brittle. I might need a softer cutting mat, but considering the (lack of) force I'd need, the softness shouldn't be much an an issue. And the cubic zirconia knifes I have do experience significant wear, judging by how quickly they lost their reasonably-sharp state and are no longer superior to a regularly sharpened (cheap) steel knife. One would probably need a hard-ish backing, e.g. maybe something like an edge-hardened steel blade, but with the thermal expansion coefficient matched to the diamond edge/insert. [0]: https://scienceofsharp.wordpress.com/2014/01/25/quantifying-sharp/ https://scienceofsharp.wordpress.com/2014/01/25/quantifying-... [1]: https://scienceofsharp.wordpress.com/2015/03/24/sharp-and-keen-part-2/ https://scienceofsharp.wordpress.com/2015/03/24/sharp-and-ke...