Sintered Metals & Ceramics: Possibly In Spyderco's Future?

[Cliff Stamp]

Damasteel :

"It is significant feature of the invention that at least two stainless steel materials having different chemical compositions are bonded together through hot isostatic compaction at a pressure exceeding 600 bar and a temperature exceeding 1000° C."

The full patent : https://www.google.ca/patents/US5815790 ... CB4Q6AEwAA" target="_blank

Note that in blending steels, either using PM or traditional forge welding, it isn't as simple as say taking S5, AEB-L and 10V and blending them to get something which has the toughness of S5, the apex stability of AEB-L and the wear resistance of 10V. It is likely what you would end up with is a steel which is a muddled bit of all of them because of the inability to harden it to optomize any aspect and the severe inhomogeneity of the steel.

[Bill1170]

Damasteel :

"It is significant feature of the invention that at least two stainless steel materials having different chemical compositions are bonded together through hot isostatic compaction at a pressure exceeding 600 bar and a temperature exceeding 1000° C."

The full patent : https://www.google.ca/patents/US5815790 ... CB4Q6AEwAA" target="_blank

Note that in blending steels, either using PM or traditional forge welding, it isn't as simple as say taking S5, AEB-L and 10V and blending them to get something which has the toughness of S5, the apex stability of AEB-L and the wear resistance of 10V. It is likely what you would end up with is a steel which is a muddled bit of all of them because of the inability to harden it to optomize any aspect and the severe inhomogeneity of the steel.

Ah, so it has been done. Thank you, Cliff.

[SpyderEdgeForever]

Diamondoid. Lot's and lots of diamondoid and related materials:

Fullerene/Buckyballs/Buckytubes mixed with and composited with diamond and diamondoid.

http://phys.org/news/2014-09-buckyballs ... adget.html" target="_blank

https://www.princeton.edu/~achaney/tmve ... ndoid.html" target="_blank

" A diamondoid, in the context of building materials for nanotechnology components, most generally refers to structures that resemble diamond in a broad sense: namely, strong, stiff structures containing dense, 3-D networks of covalent bonds, formed chiefly from first and second row atoms with a valence of three or more. Examples of diamondoid structures would include crystalline diamond, sapphire, and other stiff structures similar to diamond but with various atom substitutions which might include N, O, Si, S, and so forth. Sp²-hybridized carbon structures that – in contrast to sp³-hybridized carbon in diamond – arrange in planar sheets ("graphene" sheets) are sometimes also included in the class of diamondoid materials for nanotechnology, e.g., graphite, carbon nanotubes consisting of sheets of carbon atoms rolled into tubes, spherical buckyballs and other graphene structures."


Also, biomimetic ceramics and advanced polymer-ceramic compounds. Man, the list can be nearly endless.

Great question, and great posts!

[bluntcut]

Excellent point, Cliff! I agree with you.

Note that in blending steels, either using PM or traditional forge welding, it isn't as simple as say taking S5, AEB-L and 10V and blending them to get something which has the toughness of S5, the apex stability of AEB-L and the wear resistance of 10V. It is likely what you would end up with is a steel which is a muddled bit of all of them because of the inability to harden it to optomize any aspect and the severe inhomogeneity of the steel.

In advance - please forgive me for my rusted science babbling...

In doing ht tinkering/research, my general objective is:
* obtain global minima energy potential configuration in large matrix(simulation per say) consist of structures weave together mostly by lattice and covalend bond (for non-steel-matrix).

It's interdisciplinary optimization of: finite elements, combinatorial, chemistry and structural physics. When # of variables (elements; size; shape) count is low - e.g. steels with simple composition - often there is a general global energy minima configuration. The closer you get toward that minima, the stronger+tougher+flex+etc.. outcome. As # of variables increase, many local maxima appear and if global minima still there, it will has higher energy potential. After some upper threshold of variable count, global maxima disappear, replaced with a lot of local maxima. Steels at this stage are plain brittle, because they don't require much energy to get out of a shallow energy hole/maxima. Fracture or unwanted transformation occurred.

Similar to nanotube/graphene/etc. A perfect iron structure(mostly up to a few hundreds nm total in size) shown to have super strength/toughness too. But the law of large number drastically reduce probability 'perfect' to 'impossibilities'. This is the case where the whole configuration look like a bowl, 1 global minima, where the wall consist of this 'perfect' structures bond or crystalize next to each other. In practice/reality, impurity & mfg processes problem crumble this wall of 'perfection'.

[Cliff Stamp]

In doing ht tinkering/research, my general objective is:
* obtain global minima energy potential configuration in large matrix(simulation per say) consist of structures weave together mostly by lattice and covalend bond (for non-steel-matrix).

Ha, you should use that as the tag line on your knives.

As an aside, interestingly enough, I was able to locate active research in extreme quenching of steels and the effects on martensite formation, including martensite formation well above the Ms point. The rates of quenching are orders above brine in terms of temperature gradients and come into play in welding large parts where the heat sink potential is essentially infinite compared to the media being cooled. I am still wading through some of the references now, but in contrary to popular web-belief, ultra-high speed quenching is researched in martensitic formation.

[Bill1170]

Isn't friction forging an example of ultra high speed quenching as applied to cutlery? Same dynamic of very local liquification amidst a large cooler solid mass of metal.

[Cliff Stamp]

It is a combination of very high soak+minimal time, mechanical deformation and fast soak which produces an extremely fine aus-grain, very fine distribution of carbides and extremely high working hardness. I have one of the blades on a pass around.

[bluntcut]

Thanks Cliff. I am looking forward to hearing your take on this mart-ultra-quench, share here or on your forum. Is it related to on going UHC research?

As an aside, interestingly enough, I was able to locate active research in extreme quenching of steels and the effects on martensite formation, including martensite formation well above the Ms point. The rates of quenching are orders above brine in terms of temperature gradients and come into play in welding large parts where the heat sink potential is essentially infinite compared to the media being cooled. I am still wading through some of the references now, but in contrary to popular web-belief, ultra-high speed quenching is researched in martensitic formation

Somehow my mind closed shut - a few years back - on friction forge, after I spent a few hrs in estimating how heat propagation/radiate into blade from a small friction disc (basically a dry mill head). One side of the bevel will has diff transformation than the other due to heat gradient and material displacement.

It is a combination of very high soak+minimal time, mechanical deformation and fast soak which produces an extremely fine aus-grain, very fine distribution of carbides and extremely high working hardness. I have one of the blades on a pass around.

Hey Scotty beam me up... so I can use the conherent focusing inductor with dual-opposing ultra-sonic ceramic composite heads to epsilon nucleatized then 10 above Kelvin flash my blade :p

[JD Spydo]

I hope this is not too far off topic but I had been meaning to bring this up for some time>> About 8 years ago "BLADE" magazine did a huge article on a metallic epoxy type material call "LIQUIDMETAL" >> In the article they listed a lot of advantages this knife material had going for it.

Corrosion resistance topped the list and they bragged that it had a lot going for it for use in harsh environments. To me it seemed like an epoxy version of H-1 because it had a lot of the traits of nitrogen based steels. Just wonder if any of you guys have had any experience with it or know anything about it. Never heard any follow up after the BLADE article.

[SolidState]

About 8 years ago "BLADE" magazine did a huge article on a metallic epoxy type material call "LIQUIDMETAL" >> In the article they listed a lot of advantages this knife material had going for it.

Liquidmetal is an amorphous metal, or bulk metallic glass material. Typically, the Liquidmetal concoctions are a mix of zirconium, copper, aluminum, nickel with some large atom like Barium. Initial mixes were not amenable to grinding or heat really in general and would have to be cast. More recent mixes have been reported to have better machining capabilities, but I have yet to see that in the avenues of amorphous metal that I work in. These are typically melts that are quickly cooled. Pseudo-ceramic sintered pucks of the desired metallic composition are typically sintered under argon and sold for use in semiconductor industrial processes like sputtering.
Last I read, multiple makers have had disappointment with the material upon trying to make edged implements. Unless cast, and ion beam sharpened, I would assume that you won't get a good edge on the stuff just because of how sharpening works. I know the Chinese had a small market for barium-free amorphous metal in scalpels, but that's about it.

With Amorphous metals, most of the beneficial material properties come from atomic confusion - the absence of a crystal. This is typically induced by having all different sizes of metal atoms in the mix - prohibiting a regular repeating structure. Another key component is having metal atoms with different propensities to give away their electrons. Some give and some take, making a kind of ionic situation (+ and - charges) Think about glass vs. steel. Liquidmetal acts more like glass, and less like metal. A processing problem is that the metals used often involve very electropositive elements like zirconium, aluminum, and titanium. These metals are quite reactive and require special processing of melts.

The ability of amorphous metal to have a smooth, as-processed surface allowed us to patent tunneling devices using Amorphous metals as electrodes - because they are smooth down to the atomic level (0.1 nm). I have made free-standing amorphous metal layers of 8 nm in thickness - so I'm aware that it CAN take an edge. The thinnest edge I have seen it take was 3nm. The problem is that when it goes from amorphous to crystalline it goes from being as hard as glass and sturdy as steel to as soft as copper and kind of brittle like rust. The zirconium oxidizes and the copper crystallizes into a copper nickel alloy. What I saw were maximum processing temperatures of 300 C. Damage from exceeding that temperature could permeate multiple microns into the material. I would assume that makes stone grinding an edge on the stuff pretty darn difficult.

[Bill1170]

SolidState, what is the work of fracture like on the amorphous alloys you've worked with? How does the toughness compare with simple steels at comparable hardness? Would there be anything resembling a dislocation mechanism (in practical effect) in a metallic glass?

[SolidState]

SolidState, what is the work of fracture like on the amorphous alloys you've worked with? How does the toughness compare with simple steels at comparable hardness? Would there be anything resembling a dislocation mechanism (in practical effect) in a metallic glass?

I haven't done anything with steels of comparable hardness in the lab, so it is hard for me to comment on macroscale toughness.
My experiments looked primarily at surface effects, crystallization, and corrosion mechanisms of amorphous metals. The studies are primarily on electronics-scale geometries, and not knife blades.

For most experiments the fracture patterns mimic those of SiO2 glass on an SEM scale. That is to say that the pressure wave of the fracture dictated the appearance of the surface along the break. No grains or domains were present in the images as is normal with polycrystalline metals. It is kind of neat on an SEM to see the pressure wave carry over into the metal from thermally-oxidized silicon, as the metal gives great contrast. I must put the caveat in that I've looked at maximum thicknesses of 200 nm of Titanium Aluminum, Zirconium Copper Aluminum Nickel, and Copper Zirconium amorphous alloys. Further, electron diffraction indicated very little order in these materials and was backed up by transmission electron microscopy showing the same.

The only hardness indicators I have were nano-indentation studies using diamond points, and those tests put it below amorphous silica and amorphous alumina but higher than most steels. I'm not sure I can say much more than that.
I hope this helps.

[Cliff Stamp]

I would assume that makes stone grinding an edge on the stuff pretty darn difficult.

I have used the original liquid metal, it isn't overly difficult to sharpen though originally there were some complaints about it. Similar to the cobalt based alloys, or things like SM-100 or even beta-ti, they don't react exactly the same to abrasives as steel and thus you have to adjust how you are sharpening. Often it is a case of not being as dependent on burr formation, or dealing with excessive tenancies to load (titanium is very annoying in that respect).

The big problem with them is often than they are very weak compared to steel, especially in thin cross sections hence why you don't see things like yield points noted as these often are horrible compared to cutlery steels. SM-100 for example, even though it has similar hardness to cutlery steels, has an much lower yield point .

[Bill1170]

Thank you to SolidState and Cliff for your latest replies. They help paint the picture. Modern steels still look pretty impressive overall when compared with new experimental materials. It pays to keep looking.

[SolidState]

Hi Cliff,

Did you see a lot of plastic deformation out of thin cross sections?

[Cliff Stamp]

Did you see a lot of plastic deformation out of thin cross sections?

No, it was brittle fracture :



The fracture was so extreme that the edges were actually sharp, very little deformation. To be clear though this was a particular alloy in a particular thermal processing/composition. I would not infer from this properties of the entire field of alloys no more than I would use one "steel" knife and generalize to how all steels behave.

I did find in general that the combination of edge retention (across many different media/cutting types) and brittleness was not overly attractive. It was outperformed by even very basic 12C27 knives on abrasive cutting but yet had no where near the toughness. However it is only through experimenting with various things do we find what works. The successes are often dependent on failures to be found.

The other alloys behave differently, beta-ti and SM-100 for example are not very much in common aside from both should be ground like titanium. The working hardness and toughness ranges are very different, both have low yield points.

[SolidState]

Thanks for the great info Cliff. That image is what I was hoping to see.

We typically sputter-deposited the metals for my studies, and if we went thicker than 2 micrometers, the film would actually crack from internal stresses. I think the elasticity in these materials in terms of ball bearing rebound-type measurements is really a misguided interpretation of something that is metallically conductive having ionicity approaching that of more ionic materials.

Like you said, other materials have vastly different qualities. We have also found that the titanium-based materials act completely differently than the zirconium-based ones.

[Cliff Stamp]

What would be nice to see in general for anyone making that kind of claim would be to see some actual properties related to the actual use. But of course I am looking at it from the point of view of understanding it not from the perspective of selling it. In many cases a lot of these move/sell as collectibles and a liquid metal blade sounds like a pretty cool thing, especially compared to something which is basically used to make lawnmower blades, not very interesting at all. I had a bunch of blades made out of SM-100, interesting material. None of them are impressive material wise (low strength, very brittle) but they again are interesting pieces collection wise.

However all of these things may be obvious in use, but you can only get there if someone is willing to make a knife out of it and you might never know about it until someone gets the idea to do so. Hence why I have a lot of positive views on people who experiment, even if some of the choices are odd. It isn't like we know that much about properties of materials that is is obvious from composition if something would work well or not anyway.

[JD Spydo]

What would be nice to see in general for anyone making that kind of claim would be to see some actual properties related to the actual use. But of course I am looking at it from the point of view of understanding it not from the perspective of selling it. In many cases a lot of these move/sell as collectibles and a liquid metal blade sounds like a pretty cool thing, especially compared to something which is basically used to make lawnmower blades, not very interesting at all.

Cliff I assume you're just kidding about LAWNMOWER BLADES being made of Liquidmetal?? Which makes me wonder what primary use they had for the material to begin with. From what I can remember of that article in BLADE magazine they really didn't say what it's creators made it for primarily.

Also I remember BOKER using a material called "CERMET" for knife blades. I actually had one of them but later traded it to Dr. Hannibal Lecter here at Spyderville. I'm also wondering what you and Solidstate might know about that material?

[Cliff Stamp]

Cliff I assume you're just kidding about LAWNMOWER BLADES being made of Liquidmetal??

I guess I didn't write that very clear, when I wrote this :

"In many cases a lot of these move/sell as collectibles and a liquid metal blade sounds like a pretty cool thing, especially compared to something which is basically used to make lawnmower blades, not very interesting at all. "

I meant that many common knife steels are used to make some very basic things like lawnmower blades. Having a knife which is made out of the same materials which is used to make a handsaw or lawnmower blade isn't as exciting to some as that which is used to make a jet turbine or some other much more exotic type use.

Also I remember BOKER using a material called "CERMET" for knife blades.

Cermets are basically composites of steel and ceramics which attempt to give ceramics some of the toughness of steel, they are usually much more ceramic than steel. There are entire classes of such super alloys which use various binders (cobalt is another) to try to balance the necessary toughness with the extreme wear resistance, hardness and heat resistance of carbide. I am not sure in general any of these types of materials would actually be superior to steel for a knife assuming you wanted one which was designed to cut well. They however can work very well in particular applications.

For example there are lots of craft knives now which have tiny ceramic scalpels which just barely stick out from the holder. I have bought a bunch of them as gifts and they are very well received. As the load/shocks are essentially zero, and you are doing just very soft and abrasive cutting then those little ceramic blades will keep cutting paper much longer than even HSS would, plus they don't rust. But if you put the same type of material in a knife then you get into an issue where the lack of ductility and toughness will reduce cutting ability as you will be forced to thicken the profile.