Precrack preparation problem on WC/Co CT sample

Hi All

Can someone help mi find any method to prepare SHARP precrack on CT sample of Wc/Co ?

I need to gain R-curve but I have no idea how to make proper preparation of ma samples. What I did already

Made a incline notch
Vickers Indent (no indents crack) Samples were polished by 9mikron and marked by 1mm step After that stress concetration is too big - I broke sample

Fracture toughness is about 13-15

Fatiging it does not make sense because of fine grain size and I think there is no fatigue effect in ceramics

Has anyone experience of that kind of tests or an idea how to test this really brittle material?

Marcin Knec

WC - Co is ceramic particles in a metal matrix. It does fatigue but you are correct about the fine grain properties.

What the hey, give the fatiguing a shot.

good luck, Tom

P.S. You might try the ASM web site. They have a society of carbide tool engineers.

Ok thank You. I'll try to find a little deeper :) because society of carbide tool eng is providing tool for cuting only.

Marcin Knec.