How to determine ceramic fracture toughness?

[ceramix]

Hello, everyone!
I am quite new in this area (technical ceramics) and there are few things bothering me...

First, and the most important one, is the ceramics fracture toughness. I have read so many scientific papers about this subject and I am nothing but confused :-(

So, to shorten this, I will just ask this: do you know which of the popular models (Anstis, Niihara, Lankford, Casellas, Lawn...) are STILL applicable? Or, in other words, which WERE NOT denied during the last years?

Thank you very much!

 

[cloa]

Anstis must be of great one. Its still referred to.

http://cmr.curtin.edu.au/archive.cfm

 

[cloa]

http://ceramics.org/acers-community/award-winners-resources/?bio=15891

 

[ceramix]

@cloa: Thank you, but i still have questions...
I had used the Anstis model, but a colleague from another country told me this model is applicable ONLY for median / radial cracks, while I have Palmqvist...

Is he right?

 

[ceramix]

I've just read paper written by Gong et al. (Indentation toughness of ceramics: a modified approach, 2002).
They say that the Anstis model is applicable only when using the Vickers indenter (or: it's not suitable for Knoop hardness testing).

What do you know about this?

And about my previous question (previous post) ?

Thank you!!

 

[ceramix]

Hi, again.

I would really appreciate if ANYBODY tries to discuss this subject with me. Please, I'm in the research dead end :-(

 

[cloa]

I am sorry that you haven't had much replies. I only did one ceramics unit in my Materials Engineering degree and maybe fracture mechanics.

 

[cloa]

http://www.physicsforums.com/

might be worth a try or directly contacting a ceramics academic.

 

[ceramix]

Hello, once again.

I just wanted to inform you that I've finally (kind of) found the solution for my problem and I want to share it with you all, in case someone else needs this information.

The answer was in the work Fracture Toughness of Ceramics by the Vickers Indentation Crack Length Method: A Critical Review, written by Quinn.

I'm not sure what's with copyright, so I won't be so precise with my explanation, but the general idea (as I've understood it) is: indentation method is unreliable and should not be seriously used, and none of the models gives satisfactory results.