Re: Borosilicate glass -- easy fracture?

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.

--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf
.

Relevant Pages

  • 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? ...
    (sci.materials)
  • Re: Borosilicate glass -- easy fracture?
    ... >borosilicate glasses didn't fracture as easily as natural untempered ... >borosilicates any more or less apt to fracture or shatter than regular ... Because Pyrex has a low thermal expansion coefficient, ... but chemical toughening is feasible. ...
    (sci.materials)