EDGE RETENTION/ROLLING PART II

[KnifeGrinders]

Our SET-testing results of ceramic knives are in line with Mike's findings:
sharpened at the same dps and to the same initial sharpness, the ceramic edge lasts 6 times as long as a quality boning knife (0.5% carbon, 56-58 HRC), and twice as long as a Vanadis-10 knife (2.9% carbon, 9.8% Vanadium, 63 HRC).

The ceramic knife I've tested is Zirconium Dioxide of a cheap make, that you can buy under $10 retail, and for $1.00 bulk from China.

No rolling in the impact area as you would expect, but microscopic chipping as seen in the below image taken after 600 impact cycles when the edge started scoring blunt over 500 BESS. The chipping develops on the side of the blade opposite the impact roller, i.e. where on a steel blade you would feel the rolled/bent apex.



Now to the most interesting part - correlation between the ceramic edge retention and angle is reverse to what we've seen in steel knives.
The above results are for a ceramic edge sharpened at 12 dps.
The ceramic edge sharpened at 15 dps stays by 30% sharper and lasts by 3 times longer than the ceramic 12 dps - it took 600 impact cycles for the 12 dps ceramic edge sharpness score to go over 500 BESS, and more than 1500 cycles for the 15 dps.
The 15 dps (30 degrees included) ceramic edge stays sharp longer than a steel boning knife at least by 15 times, and longer than Vanadis-10 at least by 5 times.
I say "at least" because I didn't have patience to continue rolling the edge till its sharpness scores over 500 BESS - it didn't after 1500 impact rolls, and I stopped there.
Microscopically I didn't see any chipping in the impact area on the 15 dps edge.




Impact roller wear in the ceramic knife test: