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peculiar strop question

N

Nebulae

Joined
Aug 24, 2009
Messages
1,260
So I got some diamond paste in the mail today (1/.5 micron) and immediately I go and start working on my knives, but a question occurs to me. I have a knife with a tungsten carbide blade, so if I strop it, it will leave behind little tiny tungsten carbide particles. Since these particles are very hard they will cut steel, behaving like a compound. So will the WC particles that get abraded away by the diamond compound be bigger or smaller than the abrasive particle that removed them?
Its a really interesting problem that I had never thought of before.
 
Sure, PM steel carbides will deposit themselves on the strop, with carbides size from 2 to 8 microns. Yes, those carbides are now will abrade as an abrasive would. When I detect - hear/feel - the present of these large (larger than my cbn/diamond compound) particles, I brush them off using a piece of toilet paper. leave them there = mysterious scratches on current and subsequent knives. N/A to carbon knives, i.e. no carbides.
 
It is a peculiar question, but interesting to ponder all the same.

I'd assume the WC particles would be smaller (assuming much smaller) than the diamond particles. Being that the WC is extremely hard, the diamond wouldn't (I assume) dig as deeply into the blade as it might if abrading something softer, like buttery-soft 1095 steel (relatively speaking). Only a small portion of each diamond particle's surface area would be making direct contact on the blade's surface, so the amount of material displaced should be small by comparison. Whatever swarf comes off, I'd imagine it would be quite fine.

Comparing with other sanding/filing/abrading tasks, where both the abrasive particles and the 'dust' generated are coarse enough to actually see by the naked eye (and feel by touch), the 'dust' is always much finer than the particles of abrasive making it. I'd have to assume the same would generally hold true, with other materials at much smaller sizes.

It would be very interesting to see microscopic images of the swarf generated, to see what shape they take too. In my mind (read: complete speculation ;)), I'm wondering if they'd actually look like particles per se, or maybe like thin shavings/strands, such as might be seen coming off a piece of wood when being filed/carved/planed, or from a piece of steel being turned or milled in a machine shop.

Hmmm.... :cool:

Edit: bluntcut's point about the large carbides breaking out makes good sense.
 
Take S30v for examples: 4% by content is VC with average size is 2microns. If strop began at 1micron avg thick apex, likely that there would be 4%+- VC sitting on and near the apex. Well, diamond will abrade away steel & VC, sure alot more steel even to the point that VC just fall off from steel matrix. ugh quite a few VC on compound loaded strop. For plain leather strop, silicate can knock some barely hang-on VC from matrix.

Avg WC in cpm-m4 is around 4microns due to clumping. Hey, could be worse like D2 (non-PM) mondo carbides 10-20microns.
 
Obsessed with edges, you thoughtfully put into words my own suspicions on the subject. I was wondering about possible ribbons, as you mention, but upon further thought I doubt WC would do that, it seems too hard and brittle. But now I wonder what shape do the swarf particles take? Knowing this would help me to understand what is really goingis on. I wonder if tribology can give a satisfactory answer.
As for the carbide tearout, that is interesting too, I had never really considered that, but I don't imagine it would be too much of a problem, because the diamond should cut the carbide, not tear it out especially on a strop. However this could be a problem on a super fine Arkansas stone, or silacate or CrO strop and it would certainly be more common than my particular case.
 
tungsten blade or tungsten coated blade? i have never seen a knife with a solid tungsten blade.
 
bluntcut said:
Sure, PM steel carbides will deposit themselves on the strop, with carbides size from 2 to 8 microns. Yes, those carbides are now will abrade as an abrasive would. When I detect - hear/feel - the present of these large (larger than my cbn/diamond compound) particles, I brush them off using a piece of toilet paper. leave them there = mysterious scratches on current and subsequent knives. N/A to carbon knives, i.e. no carbides.
Click to expand...

This reply makes my head hurt.
 
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