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

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.

Interesting. Thanks for the information. This might explain why my Manix 2 with s110v doesn t stay sharp as long as I would expect after a prolonged session with my SM medium rods. Maybe I ll just try the cbn rods followed by some stropping with plain leather.
 
Interesting. Thanks for the information. This might explain why my Manix 2 with s110v doesn t stay sharp as long as I would expect after a prolonged session with my SM medium rods. Maybe I ll just try the cbn rods followed by some stropping with plain leather.

FortyTwoBlades' explanation was dead-on, and it points out the reasons I eventually backed away from using ceramics in trying to refine high-wear steels. It 'sort of works' for a while. But then you'll start noticing the edge is losing it's bite and is becoming somewhat overpolished and rounded off, and the ceramics are having a tougher time bringing it back. Then, a few easy, light passes with a similar-grit diamond hone (i.e., ~ 1200 or finer) restores the 'bite' very quickly; that's when the light bulb clicks on, about what the ceramic is missing in capability with these steels.


David
 
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Is there any sort of consensus on how much vanadium content it takes to become problematic on ceramic sharpeners? Or is any vanadium content at all problematic, and it's just a matter of degree?
 
Is there any sort of consensus on how much vanadium content it takes to become problematic on ceramic sharpeners? Or is any vanadium content at all problematic, and it's just a matter of degree?

For me, I couldn't help but notice the shortcomings of ceramics on steels like S30V (4% vanadium), or sometimes even D2 (the ingot, non-cpm variety with HUGE chromium carbides). Vanadium isn't much of a factor with D2, but the size of the still fairly hard chromium carbides in D2 adds enough wear resistance, that I start looking elsewhere for better sharpening solutions (SiC or diamond, namely).

It isn't as much about the aluminum oxide abrasive in the ceramics (though AlOx is still limited in effectiveness on the much harder vanadium carbides), but the nature of sintered ceramics themselves, which leaves them prone to loading up very fast, at which time they become almost entirely ineffective on very wear-resistant steels. Other aluminum oxide stones (oil stones, water stones) or abrasives (compounds, or sandpapers) can still work very well on D2; but, sintered ceramics have their own unique handicaps in some kinds of sharpening jobs.


David
 
Vanadium carbide will rapidly wear on the abrasive, which, in sintered ceramics, doesn't shed. You'll glaze the stone much more rapidly that way and then have to refresh the surface with a diamond plate or other superabrasive to remove the dulled surface layer.
 
Could someone show me where I can see some pictures of carbide tear out?
....
Also, any pictures of Bigfoot would be appreciated...

I've searched for evidence of "carbide tear-out" and only ever found that one image from Roman Landes' thesis (IIRC, it was a 30 micron carbide particle). I've seen no evidence that it's an issue in these steels where the carbides (in my experience) are 0.5 - 1 micron in size.
 
So you are saying that even s30v, which is quite the bulk in for example spyderco s lineup, is illsuited for their sharp maker ceramics?
 
Also, any pictures of Bigfoot would be appreciated...

I've searched for evidence of "carbide tear-out" and only ever found that one image from Roman Landes' thesis (IIRC, it was a 30 micron carbide particle). I've seen no evidence that it's an issue in these steels where the carbides (in my experience) are 0.5 - 1 micron in size.

It's a rare day I get to participate in this part of the forum, so.. jumping on the chance.

Bigfoot picture as requested ;)

tip%2Btop1.jpg
 
So you are saying that even s30v, which is quite the bulk in for example spyderco s lineup, is illsuited for their sharp maker ceramics?

Speaking for myself only, I'd just say there are better alternatives for sharpening S30V. Not sure I'd describe it as 'ill-suited' though. If one were to set a good edge with a diamond hone on S30V, it can be maintained to adequate or good sharpness for a while on a tool like the Sharpmaker. But after a number of touch-ups on the ceramic, even if one is doing a diligent job not letting the original edge get too far-gone, some of the original bite in the edge still goes away, and it needs something better-suited to the steel to bring the bite back.

I have a few of Spyderco's S30V blades myself (3 Military, 1 Para-Military, 1 Manix). I tried using ceramics for a long while, to maintain the factory edge on them. It worked OK for a while, keeping them functionally sharp. But the edges eventually became over-burnished on the ceramic, and it then had trouble restoring the original factory sharpness. That's when I started looking for something better able to deal with the vanadium carbides in the steel. At coarser grit, SiC handles it pretty well. Getting down to 10µ grit or lower, diamond makes a huge difference in sharpness, and with much, much less effort expended.

And I think even Spyderco knows this as well, since they've also offered diamond/cbn options for the Sharpmaker itself.


David
 
Speaking for myself only, I'd just say there are better alternatives for sharpening S30V. Not sure I'd describe it as 'ill-suited' though. If one were to set a good edge with a diamond hone on S30V, it can be maintained to adequate or good sharpness for a while on a tool like the Sharpmaker. But after a number of touch-ups on the ceramic, even if one is doing a diligent job not letting the original edge get too far-gone, some of the original bite in the edge still goes away, and it needs something better-suited to the steel to bring the bite back.

I have a few of Spyderco's S30V blades myself (3 Military, 1 Para-Military, 1 Manix). I tried using ceramics for a long while, to maintain the factory edge on them. It worked OK for a while, keeping them functionally sharp. But the edges eventually became over-burnished on the ceramic, and it then had trouble restoring the original factory sharpness. That's when I started looking for something better able to deal with the vanadium carbides in the steel. At coarser grit, SiC handles it pretty well. Getting down to 10µ grit or lower, diamond makes a huge difference in sharpness, and with much, much less effort expended.

And I think even Spyderco knows this as well, since they've also offered diamond/cbn options for the Sharpmaker itself.


David

Thanks for your reply... I still wonder though what options there are for a fine finish in that case... DMT extra extra fine? shapton?
Or is all this grit progression and extra high grit finishing pointless with these steels as mentioned in the video above?
 
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Also, any pictures of Bigfoot would be appreciated...

I've searched for evidence of "carbide tear-out" and only ever found that one image from Roman Landes' thesis (IIRC, it was a 30 micron carbide particle). I've seen no evidence that it's an issue in these steels where the carbides (in my experience) are 0.5 - 1 micron in size.
Pretty sure that's what's shown here, though it's with large carbides.
 
Thanks for your reply... I still wonder though what options there are for a fine finish in that case... DMT extra extra fine? shapton?
Or is all this grit progression and extra high grit finishing pointless with these steels as mentioned in the video above?

For a really high finish (polish), I'd stick with a diamond progression. A progression through DMT's EEF (3µ) gets it very close, after which diamond compounds/pastes in 6/3/1µ sizes on hard strops of wood work really well. In particular, DMT's 3µ Dia-Paste used on wood will show a big jump in visible polish, after honing on something like the EF or EEF hones.


David
 
Pretty sure that's what's shown here, though it's with large carbides.

This is about the extent of what's usually presented as evidence - pictures of chips that could have been carbides, maybe.

I've shown this image of an S30V blade before. The dark spots are vanadium carbides - there are two right in the apex - it doesn't appear to me that the bond between the carbide and matrix is a weak point.

s30v_06.jpg
 
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To answer the OP, my experience is that any friable stone can sharpen most any high-carbide steel to an edge that draw cuts newsprint. Assuming similar pressure is applied, sintered ceramics with low bond strength can reduce time spent on a stone versus the typical. While I understand that AlOx and SiC are unable to abrade VC and arguably plough the matrix at best, I feel that even the XXF DMT produces a finish which cannot take full advantage of said argument due to the irregularity and depth of its scratch pattern. ≤ 1μm compounds and sprays, perhaps. But I have not experienced an XXF DMT finish being superior in sharpness or edge retention to that of an SPS II 3K for high-carbide steels.
 
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I think, among us we might termed/called same data differently rather than disagreed with visual data & hand-on experience. My (2nd time at this same pic) interpretation/annotation of ToddS's image above:

dsl0fu6.jpg
 
To answer the OP, my experience is that any friable stone can sharpen most any high-carbide steel to an edge that draw cuts newsprint. Assuming similar pressure is applied, sintered ceramics with low bond strength can reduce time spent on a stone versus the typical. While I understand that AlOx and SiC are unable to abrade VC and arguably plough the matrix at best, I feel that even the XXF DMT produces a finish which cannot take full advantage of said argument due to the irregularity and depth of its scratch pattern. ≤ 1μm compounds and sprays, perhaps. But I have not experienced an XXF DMT finish being superior in sharpness or edge retention to that of an SPS II 3K for high-carbide steels.

Sintered ceramics inherently have among the highest of bond strengths that are able to be produced with a particle size so small (typically 3µ and less.) I think you may have intended to say vitrified rather than sintered. Spyderco's ceramic stones are an example of sintered ceramics. Ceramic-bonded Japanese water stones would be an example of a vitrified bond with a low bond strength.

Edit to add: Typical pressure when sintering alumina is 14,500-21,750 pounds per square inch. That's not a typo. Firing temperature is 1600°C (2912°F). Pressure and temperature for vitrified ceramics, while still quite high, is nowhere near that extreme. Usually more like 150-10,000 PSI and 1400°C (2500°F).
 
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Stu from TFJ has mentioned that the SPS II series uses a form of sintering:

Sintering as I understand can be done by several different methods, only one of which is compression and heating at the same time. Another is to use a binder which is completely vaporised during firing, separating the compression and firing steps and giving a porous material with no residual binder.

That’s how I read it from what they’ve given me. I need to get back to them about a few points, specifically the sintered stuff and whether it’s actually done as compression/heat together or separately (nobody’s ever asked, just taken the words of compression and heat and surmised it was at the same time) and a few other details.


But then again, the stones may very well be classified as vitrified with definitions lost in translation.
 
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