On 30/01/2020 13:12, The Natural Philosopher wrote:
On 30/01/2020 12:49, newshound wrote:
On 30/01/2020 09:25, wrote:
On Wednesday, 29 January 2020 18:23:27 UTC, Tim+Â* wrote:
I have a ceramic knife that I use a lot but its definitely
beginning to
lose its edge.

Are they worth sharpening, and if so, whats the best tool? Diamond
file?
If so, what grade?

Tim

Diamond. A set of 3 in different grits is a good plan.

I'm half way between you and Chris, I'd use my double sided diamond
file, coarse side first!

Interestingly, there is a difference between "polishing" and
sharpening by grinding. As I am sure you are all aware, the Moh's
scale is based on finding one material that will actually scratch
another, and I suspect that diamond will not scratch zirconia.

But you can, actually, polish diamond with a material that is less
hard. The surface gets smoothed by a process of deformation rather
than material removal, caused at least in part by softening associated
with frictional heating. So you may be able to improve the cutting of
a ceramic knife with a softer material.

See "Bielby layer".

https://www.lehigh.edu/imi/teched/Gl...e_Lehigh .pdf

stropping a razor?


Yes, another good example. Another thing this is doing is removing any
little curls of swarf left by the previous process. I think that is also
one of the things behind the Ray Mears trick of finishing off a knife
blade against the edge of a car window.