"Ed Huntress" wrote in message
...
Some of the engineering ceramics are unbelievable.

....
It dug a 1/2" gouge in my door. But it didn't break the first time. I
really
had to hit it very hard before it broke.

The funny thing about this story is Si3N4 isn't really all that strong -
between porcelain and steel for reaction bonded stuff.
http://www.matweb.com/search/Specifi...bassnum=CM0019
Some of the tougher processes, HIP for instance, get up there though.

I don't suppose your sample was monocrystalline?

Tim

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