Recommendation? What are the different types of abrasive materials?

'Ceramic' refers more to the process by which the hones are made. It's not a single specific material in itself, but the result of how different non-metallic materials are bonded in a specific process, under extreme temperatures and (sometimes) extreme pressures. The word 'ceramic' is therefore ambiguous, because ceramics can be made using a wide range of different materials other than aluminum oxide, such as pottery from clay, porcelain, 'earthenware', 'stoneware', etc. The origin of the word 'ceramic' actually means 'pottery' in the oldest sense. Still other 'ceramics' are made from SiC, for example. But most of the ceramic hones we use for sharpening are made with aluminum oxide (Al2O3), be it 'synthetic sapphire' or 'ruby' or whatever.
 
Great info guys, thanks a lot.

Fortytwo: how does one dress a ceramic rod? I have a sharpmaker and I want to avoid the problem you spoke of regarding the rods cutting power deminishing.

I wish I could understand everything being said here, but there are a few terms I'm not familiar with. I'm sure I'll pick these things up eventually :).

Thanks guys,

Bo
 
FortyTwoBlades said:
It's not so much a matter of how they're made as much as the material that comprises the product. Both aluminum oxide and silicon carbide are inherently ceramics, in that they are "non-metallic solid material comprising an inorganic compound of metal, non-metal or metalloid atoms primarily held in ionic and covalent bonds."

But, as noted prior, in the knife world we usually mean it to indicate a sintered ceramic, aka "technical ceramic".
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That's where the definition of 'ceramic' looks tricky, in the sense that both synthetic aluminum oxide and silicon carbide are made in processes involving heating requisite ingredients to extreme temperatures as part of the manufacturing process. Manmade Al2O3 (raw powder form) is made in a process involving high-temperature kilns ( > 1000°C ), and SiC in a process involving electrical fusing of clay & carbon, which would obviously bring extreme temperatures as well.

Looks sort of like a 'chicken-or-egg' question, in the sense that no ceramic product would exist without some natural or manmade process involving extreme heating. That's what I'm getting at, in the sense that the heating by some process is what makes a ceramic a 'ceramic'.

( Quote below from: https://www.sciencelearn.org.nz/resources/1769-what-are-ceramics )
"A ceramic is an inorganic non-metallic solid made up of either metal or non-metal compounds that have been shaped and then hardened by heating to high temperatures."
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Obsessed with Edges said:
'Natural' stones:

Usually implies so-called 'Arkansas' stones in the U.S. They are composed of a natural mineral called 'novaculite' (silica-based). Not very hard (Knoop hardness = ~ 825 or so). These only work well with simple carbon steels and low-alloy stainless, like 1095, CV, 420HC, 440A, etc. Elsewhere in the world, other natural stone types exist. Most all natural stones won't be much harder (abrasive-wise) than the Arkansas stones. All are limited to relatively simple steels without much hard carbide content.

Man-made or 'synthetic' stones / other abrasives:

Aluminum oxide (Al2O3) -> these would include Norton's 'India' stones and many other hardware store-type oilstones, as well as many man-made waterstones. Knoop hardness around ~ 2100; suitable for a lot of middle-of-the-road steels with up to moderate wear-resistance (from something like 440C, 154CM, VG-10 up to something like D2, ZDP-189). Doesn't work quite as well with steels containing more than ~ 3% vanadium, the carbides of which are harder than the abrasive (Knoop hardness for vanadium carbide = ~ 2800 or so). Aluminum oxide is heavily used in many polishing applications (pastes, like Simichrome polish, Flitz, Mother's Mag wheel polish, etc). In such form, these also work well as stropping compounds on the same range of steels noted above. (Edited to add: ) Most 'ceramic' hones used in sharpening are also made with aluminum oxide (usually referred to as 'alumina ceramic').

Silicon carbide (SiC) -> Norton's 'Crystolon' is likely the best-known, but also the old-school 'Carborundum' brand as well. Some hardware store stones will also be in SiC (some ACE branded stones, Gator & others), as with the aluminum oxide oilstones. Knoop hardness around ~ 2600; will do better with more wear-resistant steels and alloys with a more vanadium, at coarser-to-medium finish; not as effective on such steels at higher finish/polishing stages, because SiC still isn't quite as hard as vanadium carbide. Most wet-or-dry sandpaper utilizes SiC abrasive, but some wet/dry paper also uses aluminum oxide.

Diamond -> this is the hardest of all, being the hardest reference material on the Knoop scale, assigned a hardness value of 7000. Works THE BEST with uber-wear-resistant steels having a lot of vanadium content. Think of steels like S30V, S90V, S110V, etc. for sharpening on diamond.

Cubic boron nitride (CBN) -> Also works well with high-vanadium steels. Second place only to diamond in Knoop hardness, at around ~ 4500 or so. CBN is more expensive to produce than synthetic diamond though, so stones made from it can be pricey.

Chrome oxide ('chromium oxide', Cr2O3) -> this is the same stuff originally developed as a powdered pigment for green paint. It's what 'green compound' is ordinarily made of, though some 'green' compounds may be blended with aluminum oxide as well. It's less-hard than aluminum oxide (something like Knoop ~ 1700 or so). Ordinarily only used as a metal buffing/polishing compound; works well on simpler steels with not much wear-resistance (1095, CV, low-alloy stainless like 420HC, etc).
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Very good explanations.

I just ordered a Boron Carbide Ceramic stone from GRIT-O-Matic. I don't know much about it other than it's hardness is between Cubic boron nitride CBN) and Silicon Carbide.
I'm taking a chance with it, do you know any thing about it?
 
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Boron carbide stones currently on the market are mostly dressing sticks used for dressing grinding wheels and aren't formulated for use as sharpening stones. So adjust expectations accordingly.
 
Bo-dacious said:
Great info guys, thanks a lot.

Fortytwo: how does one dress a ceramic rod? I have a sharpmaker and I want to avoid the problem you spoke of regarding the rods cutting power deminishing.

I wish I could understand everything being said here, but there are a few terms I'm not familiar with. I'm sure I'll pick these things up eventually :).

Thanks guys,

Bo
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Extra-fine diamond would do the trick. The key is to bear in mind that the extremely high hardness of the sintered bond means that surface texture will play a huge role in the performance of the end product, and so you want to dress the surface using as close to the desired finish as possible. The particles in alumina technical ceramics is usually about 3µ, give or take, so you don't have to take off much to expose fresh grit.
 
Forty: Okay so just rub a diamond stone against it for a few strokes? Would 1000 grit work for this? Or if it's 3µ would 8000 grit be better? If I don't have a grit that high can I use 3000? I'm a little confused on what is considered fine or course in diamond stones when manufacturers don't assign a grit to them. I read that the higher grit edge pro stones have diamond in them. Will they work?
Good info everyone.

Thanks a lot guys,

Bo
 
The Boron Carbide Ceramic stone came in yesterday so this morning I tried it out on a Manly Wasp S90v and a Benchmade S30v blade.
It did a very good job. Two blades is not much of a test but it's a bit harder than my Silicon Carbide so I think I'll like this stone.
 
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Bo-dacious said:
Forty: Okay so just rub a diamond stone against it for a few strokes? Would 1000 grit work for this? Or if it's 3µ would 8000 grit be better? If I don't have a grit that high can I use 3000? I'm a little confused on what is considered fine or course in diamond stones when manufacturers don't assign a grit to them. I read that the higher grit edge pro stones have diamond in them. Will they work?
Good info everyone.

Thanks a lot guys,

Bo
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Just use the highest grit you have.
 
Can someone tell me what the work sharp and Ken onion work sharp use in their abrasive belts? I read that they have special diamond ones specifically for ceramic knives, but I want to know what the original belts are.

Thanks,

Bk
 
Bo-dacious said:
Can someone tell me what the work sharp and Ken onion work sharp use in their abrasive belts? I read that they have special diamond ones specifically for ceramic knives, but I want to know what the original belts are.

Thanks,

Bk
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They dont come with diamond belts but you can get them separately. I'm not sure if they offer them in sizes for the blade grinding attachment. You have to run it at a very low rpm and use oil or water so they don't wear out.

I was trying to sharpen a 60hrc d2 blade with the stock abrasives and it was going no where. Once I got the diamond belts it worked great but I didn't lube it and it wore the belt out after two knives.

I forgot the abrasives they use though it's not that great. With super steel you will go through alot of belts.

I think that you can buy belts in the sizes you need in other abrasives from a 3rd party but I didn't get that far.
 
Bo-dacious said:
Can someone tell me what the work sharp and Ken onion work sharp use in their abrasive belts? I read that they have special diamond ones specifically for ceramic knives, but I want to know what the original belts are.
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All of the stock WSKO belts are SiC or AlO3. The "coarse" is 120 grit as I recall. The others are X65, X22, X4, and the "6000" grit purple belt.

All of those "X" numbers are micron sizes. X65 is 65 micron. You can kinda sorta convert that to "grit" using the Grand Unified Grit Chart at the top of the forum.

I've been using some replacement belts from worksharp called the stiff Norax. Norax is a belt type from Norton that has some kind of helical striping of the abrasive on the belt. The stiff part is that the belts are stiff and don't flex as much as regular belts. I like them a lot and use the X200, X100, X22, and X5. I also ordered some extremely coarse belts from them: 80 grit (AlO3) and 60 grit ceramic. Both make short work of really super duper damaged blades.

Brian.
 
Mo2: oh, so the diamond belts work on steel blades? The site said they were just for ceramic and steel would clog them. It's good to know I can use them. I may buy some.

Bgentry: thank you, aluminum oxide and silicone carbide, that's what I wanted to know. I did know that the x belts are microns and I've been studying the grit chart.

Thanks guys,

Bo
 
Diamond belts will be ruined on a powered sharpener, if used on steel (ferrous metals) and not kept cool. The clogging happens when the extreme heat of grinding breaks down the carbon of the diamond, which will then combine with the iron from swarf taken off the steel blade. It's not just an issue of the belt wearing out with use, as the damage can happen immediately on a new belt, if it gets too hot.

Iron + carbon have a chemical affinity for one another when hot; that's how steel is made in the first place. It's why industry uses CBN belts/wheels with powered grinding tools on high-wear steels, instead of diamond, because CBN doesn't have that chemical affinity for iron, and it also holds up better at high temps than diamond.
 
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bgentry said:
All of the stock WSKO belts are SiC or AlO3. The "coarse" is 120 grit as I recall. The others are X65, X22, X4, and the "6000" grit purple belt.

All of those "X" numbers are micron sizes. X65 is 65 micron. You can kinda sorta convert that to "grit" using the Grand Unified Grit Chart at the top of the forum.

I've been using some replacement belts from worksharp called the stiff Norax. Norax is a belt type from Norton that has some kind of helical striping of the abrasive on the belt. The stiff part is that the belts are stiff and don't flex as much as regular belts. I like them a lot and use the X200, X100, X22, and X5. I also ordered some extremely coarse belts from them: 80 grit (AlO3) and 60 grit ceramic. Both make short work of really super duper damaged blades.

Brian.
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Brian, are those belts for the grinder attachment or the KO as it comes? I havent even worn out any of the first KO belts that came with it.
Havent done any nice pocket knives, may not, but my mom and her friends are pretty happy and it is about all the sharpening i can do with a broken wrist.

Russ
 
I use diamond 3M belts on my modified HF 1x30. Go slow and flush with water often, they work great for sharpening. For heavier work the Norton Blaze are still my go-to.
 
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mycough said:
Brian, are those belts for the grinder attachment or the KO as it comes?
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Those belts are all for the stock WSKO. I think they have a subset of those belts available for the BGA. Part of the reason I haven't yet purchased the BGA is that I'll have to figure out if the stiff Norax are available, in what micron sizes, and then purchase them separately. ...that and I keep thinking that I'm going to buy a 1x42 Kalimazoo or equivalent at some point.

Sorry to hear about your broken wrist Russ. I hope you heal up quickly.

Brian.
 
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