Elastic Ceramic knife - 2,350 cuts by Cedric & Ada

Currawong

Currawong

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Anyone know more about this?

Pete at 'Cedric and Ada' just posted a video of a custom knife made from 'elastic ceramic' (it is slightly flexible ceramic). Quote from Pete at the end of the video: "It's pretty safe to say this is the longest lasting edge-retaining material that I can expect exists on the planet right now."

It lasted 2,350 cuts on twisted sisal rope before it would no longer cleanly slice paper - about 800 cuts more than Sandrin and about 850 more than Rex121.


Knife is experimental, made by custom maker KKnives Switzerland youtube.com/channel/UCv7WhIE11ClB9BiaJWOJZRg/

The maker commented on Pete's video:

"A quick word about sharpening, will make a detailed video on it. Sharpening is as easy (or as hard, depending how you look at it, lol) as a steel knife. Yea. For real. Will make a video on it soon. But one needs to use the following abrasive, or it will NOT work: one needs to use diamond lapping films on a squishy material like a mouse pad as backing and perform a stropping motion, using oil or WD40 as lubricant. Just like stropping, light pressure. These diamond films run for 8-10USD a pop and last suuuuper long. So the total sharpening setup will cost you less than 30USD. Again, I'll do a dedicated video on it."
 
In that same comment he also said that it “is in the same toughness range as Rex 121.” That would be pretty tough for a ceramic but of course that is about as brittle as steel can be considering Rex 121 is typically 69+ Rc and has over 30% carbide in it.
 
I saw that video earlier today - the maker also said in the comments that they plan to be selling a batch of these guys soon - for UNDER $100 each!!
 
Sounds like they got the idea from Sandrin's flexible tungsten blades.

Interesting, I'll keep an eye on this.
 
Pomsbz said:
Why wouldn't it be? Unless it's very chippy.
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What happens if you drop it onto a hard floor from counter height ? That's just for a kitchen knife .

Can you use it to chop ? Can you put lateral , prying force that would occur in normal moderate use ?

Toughness is important in many applications .

Much more so than pure edge retention alone , IMO .

You can sharpen a dull knife . A broken blade is useless .
Alberta Ed said:
Interesting, but hard to say if it's practical.
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DocJD said:
What happens if you drop it onto a hard floor from counter height ? That's just for a kitchen knife .

Can you use it to chop ? Can you put lateral , prying force that would occur in normal moderate use ?

Toughness is important in many applications .

Much more so than pure edge retention alone , IMO .

You can sharpen a dull knife . A broken blade is useless .
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Agreed..... My first thought was I don't usually drop my knives but sure as shit with my luck I'd drop this one and on concrete too, no grass!!
 
Well this one flexes so it should be less prone to chipping or shattering than a regular ceramic blade . . . which to me is even more interesting from a practical food prep perspective than its edge retention over regular ceramic blades.
 
jfk1110 said:
Agreed..... My first thought was I don't usually drop my knives but sure as shit with my luck I'd drop this one and on concrete too, no grass!!
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We already have widely available and cheap ceramic kitchen knives that are useful within reason and respecting their limited toughness .

So this new "elastic " ceramic's value will be determined mostly by the reality of the elasticity claim , i.e. toughness .
 
patrickguignot said:
I noticed he threw the knife on wood and not on concrete. But it's certainly an interesting material and if it's really less than $100 a piece I'll buy one.
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:) It does look interesting , but videos can be misleading . We shall see . :confused:

I did like the way it sliced that paper towel ! :eek:
 
I saw the video.
I was surprised at how poorly it cut that onion. The technique wasn't too bad but the blade had to be forced to get the initial penetration on the radial slices. With an onion a good sharp knife should be able to glide right into a slice not pop into it like this one did.
Not impressed at all.
 
NorthernSouthpaw said:
I saw the video.
I was surprised at how poorly it cut that onion. The technique wasn't too bad but the blade had to be forced to get the initial penetration on the radial slices. With an onion a good sharp knife should be able to glide right into a slice not pop into it like this one did.
Not impressed at all.
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I'll just believe you on the onion slicing .

I avoid it ...always makes me cry . ;)
 
The “flexibility” of a blade is controlled by its geometry. Long, thin blades flex much more easily than a short, thick one. A steel fillet knife can flex 90 degrees without breaking. The thickness of the blade also controls how much “stress” it sees at the surface which is why a fillet knife can flex that far and return straight while a chopper cannot. The chopper will either break (if it’s hard) or stay bent (if it’s soft).

The “material property” that controls how difficult it is to flex something is the “elastic modulus” which is significantly higher in carbide like from Sandrin but the blades are still flexible because they are very thin. In the case of Zirconia the elastic modulus is actually quite similar to steel according to Kyocera: https://global.kyocera.com/prdct/fc/list/material/zirconia/zirconia.html

The chart of properties shows 200-220 GPa for the modulus, steel is in the same range (also modulus is largely unaffected by heat treatment so both hard and soft steel is in that range).
 
Not on Instagram so can’t watch that video, but if you haven’t seen the YouTube by Cedric and Ada you should.
This knife (rather this material) is extremely interesting in how it performed in a very controlled experiment which Pete has been running on hundreds of blades for years, and this one WHOMPED EVERYTHING ELSE! He mentioned that other ceramic knives he’s tested have failed at around 150 cuts of twisted sisal rope because while ceramic knives stay sharp cutting soft foods, they don’t do well on coarse material and tend to chip out. That’s compared to 2350 rope cuts! Personally can’t wait to get my hands on the kitchen knife.
 
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scdub said:
I saw that video earlier today - the maker also said in the comments that they plan to be selling a batch of these guys soon - for UNDER $100 each!!
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Don't get your hopes too high just yet. Looks like the first batch of knives is small wharnie necker. This was on a post about a couple months ago. So, yea, it makes sense it would be under $100. I have a feeling a kitchen knife would be priced closer to 3 bills.

I personally would have liked the Shard design as the first model.

Don't get me wrong, though, the results are certainly interesting and I would still definitely be interested in a knife made with this type of ceramic.

I wonder if the Sandrin would be able to do a little better if the geometry was closer to the flexible ceramic proto. I think the Sandrin was set at 20 DPS while the Proto was set at 17 DPS. The Sandrin also doesn't really have a primary bevel (well, I guess the primary bevel is the edge bevel). The Torino is suppose to have an 18 DPS edge so Sandrin's ceramic can certainly maintain a thinner edge angle.
 
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Spears said:
Don't get your hopes too high just yet. Looks like the first batch of knives is small wharnie necker. This was on a post about a couple months ago. So, yea, it makes sense it would be under $100. I have a feeling a kitchen knife would be priced closer to 3 bills.
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Really?? Dang it I thought that was too good a price. Hmm - the wharnie isn’t as interesting but we’ll see...
 
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