Answered By: Regan Brumagen Last Updated: Oct 30, 2016 Views: 182
I am not a scientist, so I will be quoting from published sources (and from our Museum Scientist) to answer your questions! I am also attaching some lists of information that may be helpful to you should you need more information than the brief comments below. I would be happy to scan any interesting article, chapter or pamphlet on the attached lists. I also included an image sent by our research scientist in his answer.
Pyrex, invented around 1915, was developed from a glass Corning called NONEX. It could withstand temperatures which were rapid or uneven. Borosilicate glass was invented earlier by German glassmaker, Otto Schott in the late 19th century and sold under the brand name "Duran" in 1893. After Corning Glass Works introduced Pyrex in 1915, it became a synonym for borosilicate glass in the English-speaking world.
Vycor emerged out of Corning's research to try to strengthen and improve borosilicate. Vycor has an extremely low coefficient of expansion and can withstand severe thermal shocks without breaking. It has a high softening point--making it able to keep its shape at temperatures up to 1800 degrees Fahrenheit. It is chemically stable, so it doesn't contaminate contents of the container. Vycor is 96% pure silica.
Pyroceram is a glass ceramic invented by Donald Stookey in the 1950s. Dr. Stookey recently died, so you will probably find his name easily if you search him in google or google news. Pyroceram, famously, was used in missile nose cones and then developed into a line of housewares called Corning ware. Patent 2,920,971 was granted to Donald Stookey, for the Lithia-alumina-silica mix nucleated by titanium oxide, which was called Pyroceram 9609.
I had trouble finding the answer as to why lab ware is not made from Pyroceram (great question!!), so I checked with our Research Scientist, Dr. Glen Cook, who used to work for Corning, Inc. I am copying his response:
Very interesting question! And I think I can give a couple of good answers.
One answer is THAT IT IS! Although it’s not generally realized, the top surface of Corning’s stirring plates and hot plates is Pyroceram. The thermal shock resistance, mechanical strength, and ease of cleaning, make it a perfect material for this “portable cooktop” application. Also, it is common in labs to actually use store-bought Corningware casserole dishes and other bakeware when a larger size low vessel is needed.
But, the questioner is correct - it isn’t seen in the places one typically finds borosilicate or Vycor. Two reasons for that, really: 1) it is not transparent, and being able to visually monitor an experiment is often critical; and 2) the process to make something out of Pyroceram isn’t nearly as flexible as for borosilicates, which can be easily flameworked into almost any shape imaginable. Pyroceram is restricted generally to relatively simple vessels, or rolled into sheets. Tubing, multi-stem flasks, and the like would be very challenging even in a manufacturing plant environment, and even more difficult by a lone scientific glassworker supporting a university lab, where specialty apparatus must often be fabricated in-house.
For more info, someone in Sales in the Corning Life Sciences business division might have some comments.
I hope this is helpful and please do let me know if you'd like scans of some of the material attached. I realize some of these publications aren't readily available at many libraries!