Ceramic edge, metal blade

Aug 28, 1999
I'm interested in the concept of a composite knife with a metal body and ceramic cutting edge bonded onto it. Clearly differences in brittleness and fracture toughness could be a problem, but I would tend to believe that some pretty spectacular cutting implements could be obtained. Any experience out there?
I've never seen any (and hope never to) but I have heard of some surgical instruments such as scalpels that use glass or ceramics to obtain a super-sharp edge. Don't know how durable those might be.
I think these ceramic knives are close, but missing the obvious fix: ceramet.

Ceramet is a material that currently exists, has great hardness and tensile strength, but also is relatively tough.

There are several variants of this material, but a good way to think about it is as a ceramic with a metalic matrix, often silicon boride ceramic and aluminum for the metal matrix I believe.

It was developed as armor for aircraft I believe, and I saw a film that showed a piece that appeared to be about .5 inches thick take a hit from a medium caliber anti-aircraft cannon and suffer only deformation, no actual penetration.

Anyway, bitch'n material and would probably make a pretty good knife. I'm sure it's expensive, and I can't find a source for it, but there's got to be a market for it with people spending hundreds of dollars on collector's knives that offer little advantage in way of material or design. This stuff would really be something no and different. Be a pain in the butt to sharpen though, but what do you want?
Ceramics are not well suited to knives in and of themselves because they are so brittle. However there are ways of improving the strength of ceramics significantly such as transformation toughening which uses small particles of metastable zirconia which change phase at crack boundries generating compressive forces and thus retarding growth. Ceramics composites have fracture strengths up to 6 times as high as pure ceramics.

Cermets are totally different. These are hard carbides (TiC) in a very ductile matric like cobalt or nickel. Cermet tool wear is much faster than ceramic composites. I would also bet that the yeild would be too high to hold a crisp edge well but would be interesting to see.

NASA, or DARPA, will come through.When I went to school, there was no such subject as ceramic engineering.


[This message has been edited by ghostsix (edited 02 September 1999).]
Cermets are totally different. These are hard carbides (TiC) in a very ductile matric like cobalt or nickel.
"Hard Carbides in a ductile matrix" isn't that a description of Talonite?

SDouglas, there is a big difference between Talonite and cermets. Check out :


For more detailed information on cermets and Talnite. There is a very big difference between the two.

For example cermets have a lot of ceramic carbide (like 90%) and little matix. They could be considered as just just a bit more wear resistant and durable than regular carbides.

Talonite on the other hand is a "super alloy" and is not really accurately described as carbides in a matrix sort of statement as that leaves out a lot of details.

Appreciate the great replies.

I guess that my point of view is that if ceramic blades are viable in a specialty market that ceramic coated edges should have a broader niche. Anything as hard as a ceramic will be brittle, but a thin coating on a ductile surface won't fracture catastrophically, but will only nick. Nicks could then be diamond ground to serrations without compromising cutting power.

It still sounds like a Cemet with a modified ratio maybe 50/50 as a starting point could be interesting as a knife blade material.

We would be looking for enough really hard carbides to cut really well in a matric ductile enough to maintain strength.

It sounds like Talonite has done an excellent job of this using alloy techiniques.

Could a Cemet be engineered that had many of it's excellent qualities at a lower cost?
TDean, there are knives with coated edges, nitrided usually. I can't recall off hand who has made them though.

SDouglas, cermets are sintered, they are not heat treated thus the matrix could not be elevated to such a high % and still have a usuable material. A nickel knife, even with a large percentage of tungsten carbides in it would make a pretty crappy knife.

Cermets should be basically though of as slightly ductile ceramic carbides. However this strength is not greater by a lot. They are not recommended to replace carbides for example if breakage is a problem.

The way to go for knife blades are the "super alloys" like Talonite (yes, "super alloy" is an actual materials term).

Right now the closest that you can come to a ceramic edged blade is with the various coatings such as Titanium Nitride, titanium carbo nitride, titanium aluminum nitride and such applied over an already heat treated and sharpened blade. Until these eventually wear through, the edge holding will be extraordinary. Afterwards the proper proceedure is to sharpen the blade on ONE SIDE ONLY with a diamond stone so the hard coat is left on one side to provide wear resistance to the blade. In theory the hard coating will resist wear more than the parent steel and the edge will become self sharpening. In practice the hard coating will eventually be exposed enough to become susceptable to chipping and will have to be dressed using a diamond stone, again working on one side only.

Besides these coatings look great on a blade.