Re: Borosilicate glass -- easy fracture?

Uncle Al wrote: 
Sporkman wrote:

I was under the impression -- perhaps false -- that "Pyrex" and other
borosilicate glasses didn't fracture as easily as natural untempered
glasses, but a light impact resulting in a very sharp concoidal sliver
from the inside rim of one "ovenware" top that we have made me think
again.  Isn't most "ovenware" tempered?  I know tempering is an entirely
separate consideration from composition, but are untempered
borosilicates any more or less apt to fracture or shatter than regular
glass?



Pyrex doesn't temper given its small coefficient of thermal
expansion.  If it were tempered and you had cracked it, it would have
exploded into rounded shards.  Try dropping Corelleware onto concrete
(wear goggles).

If you ding Pyrex it chips.  It is definitely stronger, harder, and
more survivable than soda lime glass.


What is Corelleware anyway? It is the most unbreakable ceramic dinner ware ever saw.

Gordon
.

Relevant Pages

  • Re: Borosilicate glass -- easy fracture?
    ... > borosilicate glasses didn't fracture as easily as natural untempered ... I know tempering is an entirely ... > borosilicates any more or less apt to fracture or shatter than regular ... If you ding Pyrex it chips. ...
    (sci.materials)
  • Re: Borosilicate glass -- easy fracture?
    ... borosilicate glasses didn't fracture as easily as natural untempered glasses, but a light impact resulting in a very sharp concoidal sliver from the inside rim of one "ovenware" top that we have made me think again. ... I know tempering is an entirely separate consideration from composition, but are untempered borosilicates any more or less apt to fracture or shatter than regular glass? ... It turns out that the coefficient of thermal expansion of the crystalline ceramic is greater than that for the glassy outer material, which means that as the composite cools the center shrinks more than the outer part, causing the inner part to be loaded in tension and the outer part to be loaded in compression. ...
    (sci.materials)
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