Can you use ceramics to sharpen s30/90/110v or not?

[HeavyHanded]

These are pics I re-linked from an earlier post. ekretz did some incredible camera work.

https://www.bladeforums.com/threads/stropping-wear-resistant-steels-s30v-s90v-cts204p-etc.1372633/

I list the pics in order how they appear in the thread with exception of two diamond/leather stropped pics at the end.

Clearly shows the blown/partially excavated carbides. These are not Vanadium PM steels, but HSS. Still, it clearly demonstrates the possibility if not certainty on some steels of carbide displacement. If anything this would make one want to use diamond abrasive any time the carbide content is significant - I know it changed my thinking considerably.

The DMT EEF is the only fixed abrasive that really did a clean job to the apex, and still some carbides clearly got popped.


HSS with exposed carbides, abrasive used was a Suehiro 20k water stone (Aluminum Oxide abrasive).

DMT C (325)

Next, Shapton Pro 1k:

Shapton Pro 2k:

Suehiro Rika 5k:

Shapton Pro 8k:

Shapton Pro 12k:

Suehiro Gokumyo 20k:

1 micron diamond compound on leather:

...the finest SiC stone I have, a Carborundum 103

DMT EEF

Spyderco UF

Lapped Spyderco UF

5 micron diamond strop

1 micron diamond strop

 

[ToddS]

Here is another image (I've shown before) of the stropped S30V blade. The (wear resistant) carbides are sitting slightly proud of the edge, and produce a raised tail of matrix material in the down-strop direction. These are no "popped" carbides. This is also what I see in Eric's images.

 

[HeavyHanded]

Here is another image (I've shown before) of the stropped S30V blade. The (wear resistant) carbides are sitting slightly proud of the edge, and produce a raised tail of matrix material in the down-strop direction. These are no "popped" carbides. This is also what I see in Eric's images.

You do not see the empty depressions and even more critical, all the track marks from excavated carbides? You might claim on some of the stones that they are from the abrasive (despite they appear to have a uniformity of size across a range of abrasive media), but not possible with the Spyderco UF, which appears to have fared the worse of the bunch.

The ones off the Shapton 8k look like a meteor shower.

 

[HeavyHanded]

Admittedly the strop will do a more gentle job, erasing the holes just as soon as the carbides are gone and not grinding them into the surrounding to leave telltale tracks. Clearly, if the carbides wind up proud of the surrounding, at some point they fall out and leave a void that will immediately be subject to the strop erosion.

Even on your image there appear obvious remnants on the lower right side slope, a little below dead center on the apex is a void along the ridge line, just above and to the left of that is a dual depression. If it were a picture of a hillside I think we'd all agree some rocks fell out.

 

[ToddS]

You do not see the empty depressions and even more critical, all the track marks from excavated carbides? You might claim on some of the stones that they are from the abrasive (despite they appear to have a uniformity of size across a range of abrasive media), but not possible with the Spyderco UF, which appears to have fared the worse of the bunch.

The ones off the Shapton 8k look like a meteor shower.

Eric has used a glancing angle of illumination to accentuate raised features. When you strop a steel with wear resistant carbides, they become smooth raised bumps.

The human brain assumes that illumination is from above and when we look at an image illuminated from below, it confuses our perspective.

 

[cbwx34]

Clay from Wicked Edge made a post a while back of some high resolution photos... what he originally thought was particles pulled out during sharpening... he thinks now are just "remnants of old scratches"....

http://knife.wickededgeusa.com/forums/topic/small-craters-and-connected-scratches/

 

[HeavyHanded]

Eric has used a glancing angle of illumination to accentuate raised features. When you strop a steel with wear resistant carbides, they become smooth raised bumps.

The human brain assumes that illumination is from above and when we look at an image illuminated from below, it confuses our perspective.

I'm not confused by the lighting, on the Spyderco UF pics its coming right to left as clearly evidenced by highlights along the left side of the scratch depressions. When you see a dark spot and light arc to the left of it, a depression has been illuminated.

Here's what I see:
the images of the steel coming off of a waterstone or strop show raised areas where the carbides are being excavated and are higher than the surrounding - they are tougher than the surrounding material. Presumably at some point they reach a level where they no longer have enough mechanical attachment to hold on - your own pics show evidence of this in the areas I ID'd.

Is there any plausible reason to think they don't reach this point, that at some stage they suddenly begin to wear away at the same rate as the surrounding?

The factor that brings it home for me is the lack of these half exposed carbides on the Spyderco UF images. We see a range of small depressions and tracks, and no other evidence of the carbides retained in the steel. Even the DMT EEF shows some of this but to me anyway, appears significantly fewer and the line along the apex is likewise much cleaner.

Here is one of my own pics of s30v after being stropped with conventional abrasives. You can see depressions that are not related to any of the visible scratchmarks, they are the expected approximate size of the carbides. Lower right the lighting allows one to see carbides standing proud of the surrounding.

Honestly Todd, I don't expect to change your mind on this topic, but am putting it out there for general consideration. My own cut testing and anecdotal use has shown a positive change even on non-Vanadium carbide rich steel - using SIC over AlumOx yields somewhat better retention at comparable abrasive size, and using diamond improves that yet again.

Answer to the OP question - NO, not really. But if its all you have it will do OK.

 

[ToddS]

Shapton Glass 16k on a S30V knife (edge leading strokes):

Same area imaged by optical microscope and SEM....

 

[ToddS]

What I observe in the above images is that the carbides are abraded by the stone, albeit more slowly than the surrounding matrix, but they most certainly do abrade. The carbides become smooth raised bumps on the surface of the bevel, and these bumps create shallow scratches in the surface of the stone. As a result, there is a tail of matrix material trailing each carbide (following the scratch in the stone). In the above image, the grinding direction is bottom to top, so we see these tails above the raised bump.

 

[BluntCut MetalWorks]

Todds - excellent SEM pics, thanks Also feel free to lmk if my uses of your pics is improper or should treat them as non-public.

My subjective interpretation of Todds's SEM images -

1. Actual apex line is much more jagged than 'perfect apex' because carbides shielded matrix from edge leading* abrasive flow. *less shielding with edge trailing. Further more, perfect apex would decorated with near-flattened-top carbides.
2. carbides on apex are protruding and surrounding/holding by receded matrix because abrasive wear/abrade matrix many times faster than carbide. Carbide surface smoothness level indicate how much wear occurred. Look to me - protruding carbides still have surface features/textures, so wear/abrade rate is very slow.
3. Fractured site (left red ellipse) is more/less the future of area in right red ellipse -> area sub-surface has crumbled, so when the ~2um fall out will take the area with it, turning into similar site as left red ellipse.
4. Abrasive flow channeling due to carbide blockage... maybe easier to imagine this whole edge leading abrasive flow into steel as water flow onto packed mud with stone aggregates.

 

[Mo2]

Shapton Glass 16k on a S30V knife (edge leading strokes):

Same area imaged by optical microscope and SEM....

What do I need to purchase to get these types of photos? Or is this expensive lab equipment?

 

[FortyTwoBlades]

What do I need to purchase to get these types of photos? Or is this expensive lab equipment?

It's a scanning electron microscope. Not exactly the most budget-tier variety of microscope.

 

[scottc3]

What do I need to purchase to get these types of photos? Or is this expensive lab equipment?

I would find university equipment, follow the rules, play nice, write clearly, and maybe, just maybe, you could get some time and a microscopist when a slow season is at hand. Alternative would be work through your Alma Mater or industry / govt. folks you know.
NIH still offers Post processing software that is free fast extendable and easy enough for middle school kids to use, runs in JAVA so it is cross platform: ImageJ
https://imagej.nih.gov/ij/index.html

Gotta say, great thread! thx

 

[ToddS]

1. Actual apex line is much more jagged than 'perfect apex' because carbides shielded matrix from edge leading* abrasive flow. *less shielding with edge trailing. Further more, perfect apex would decorated with near-flattened-top carbides.
2. carbides on apex are protruding and surrounding/holding by receded matrix because abrasive wear/abrade matrix many times faster than carbide. Carbide surface smoothness level indicate how much wear occurred. Look to me - protruding carbides still have surface features/textures, so wear/abrade rate is very slow.
3. Fractured site (left red ellipse) is more/less the future of area in right red ellipse -> area sub-surface has crumbled, so when the ~2um fall out will take the area with it, turning into similar site as left red ellipse.
4. Abrasive flow channeling due to carbide blockage... maybe easier to imagine this whole edge leading abrasive flow into steel as water flow onto packed mud with stone aggregates.

Sorry, this was a quick and dirty freehand on one on side of the blade and I didn't create a new apex (which is why there is so much crud)....So I wouldn't interpret too much about the apex from these images, but you are correct that the carbides on the apex do protrude (with use) and produce the micro-scale roughness we associate with "toothiness"

The image below is ZDP189, and those are chromium carbides protruding from the apex after cutting some cardboard.

 

[Chris "Anagarika"]

I finally able to see the images. Not sure why.

Thanks for the discussion!

 

[BluntCut MetalWorks]

Todds - Thanks for the zdp189 sem pic! Most abrasives are harder than CrC however matrix loss rate still faster than CrC. I like this pic quite a bit because it shows possible evidence of large events in sharpening (and deduce on usage edge deformation and longevity). Here is my yet-another-interpretation

#3 - is a CrC so its matrix footing supports very little elasticity and hardly any plasticity because of very thin interface volume. Therefore lateral impact on #3 will fracture self+interface and possibly connected near by volume (whichever weaker surface). E.g. my guess - 10um wide focus lateral shallow impact on apex at #3, est most likely fracture size around: W X D in microns - 20 x 5.

 

[maximus83]

Cool pics. So what's the point you're making then, for sharpening, with regard to the OP question?

 

[adamlau]

ToddS veers yes. FortyTwoBlades disagrees. Cliff Stamp in response to this very thread also says yes. HeavyHanded says no. I say yes and BluntCut MetalWorks probably disagrees. Conclusions and interpretations are all over the place

 

[miso2]

If CBN is considered a ceramic material (I think it is), then yes.
Anyway, I guess you can use any ceramics to sharpen them without considering efficiency.

 

[Mikeg9]

Simple answer: No.

Long answer: Sort of. You can use silicon carbide and aluminum oxide stones for coarse work or sintered ceramics for just crisping up the apex in the final stages, but for your fine grit sharpening you'll need diamonds. Aluminum oxide and silicon carbide are softer than vanadium carbide, so you need diamond, boron carbide, or cubic boron nitride to abrade it. The aluminum oxide and silicon carbide will only abrade the steel matrix and chromium carbides, not the vanadium carbides.

It's one of the reasons I personally don't care for high-vanadium steels. If you sharpen them using standard abrasives you'll get the steel sharp, but will have torn the carbides out of the edge and so you're not getting any benefit from them and your edge won't hold any longer than a low-alloy steel would.

What is your favorite steel?
or best steel that could still be fully sharpened on ceramic