Pyroceram
Pyroceram is the original glass-ceramic material developed and trademarked by Corning Glass in the 1950s.[1] Pyroceram is an opaque, white, glass material, commonly used in kitchenware, glass stove tops, wood stove doors, etc.. It has high heat tolerance and low thermal expansion.
Development
[edit | edit source]Its development has been traced to Corning's work in developing photosensitive glass.[2] Corning credits S. Donald Stookey with the discovery of Pyroceram. While conducting research in 1953 on a photosensitive lithium silicate glass called Fotoform containing a dispersion of silver nanoparticles, Stookey noted that an accidentally overheated fragment of the glass resisted breakage when dropped.[3] This discovery evolved into Pyroceram, with β-spodumene as the crystalline phase, and was used in 1958 for the production of CorningWare cookware.[4] Pyroceram's thermal stability also results in its being used for mirrors in astronomical telescopes.
A transparent version of Pyroceram, with β-quartz as the crystalline phase, was also described in 1950s patents. By 1963 this variant was also being seriously studied for use in making cookware.[5] It would be extensively explored over the next two decades and result in the creation of Visions cookware, by Corning France, in the late 1970s.[6]
The manufacture of the material involves controlled crystallization.[2] NASA classifies it as a glass-ceramic product.[7]
After about 30 years of informal use as a standard in high-heat (≥1000 °C) applications, Pyroceram 9606 was approved by NIST as a certified reference material for thermal conductivity measurements.
For kitchenware, this ceramic-glass family has been composed approximately, as calculated from precursor glass batches in percent by weight on an oxide basis, of (or similar variations):
- 68.2% Silica Sand (SiO2)
- 19.2% Aluminium oxide (Al2O3)
- 2.8% Lithium oxide (Li2O)
- 1.8% Magnesium oxide (MgO)
- 1.0% Zinc oxide (ZnO)
- 0.75% Barium oxide (BaO)
- 2.7% Titanium dioxide (TiO2)
- 1.75% Zirconium dioxide (ZrO2)
Plus additional oxides and colorants depending on the product line being produced.
Trademark
[edit | edit source]Pyroceram was originally a proprietary brand name. Corning registered Pyroceram as a trademark for glass-ceramic vessels and utensils in 1958, and in 1966 added polished glass-ceramic tabletops and countertops to the registered uses of the brand name. Both of those registrations have since ended.[8]
In 1998, Corning registered Pyroceram as a trademark for clear glass-ceramic window glass for wood-burning stoves.[8] It was also studied as a material for rocket nose cones.
See also
[edit | edit source]References
[edit | edit source]- ^ M. Montazerian, S. P. Singh & E. D. Zanotto, "An Analysis of Glass-Ceramic Research and Commercialization," American Ceramic Society Bulletin, Vol. 94, No. 4, pp. 30-35 (2015).
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- ^ W. W. Shaver & S. D. Stookey, "Pyroceram," SAE Technical Papers, 90428, 1959.
- ^ US 3252811 Beall, George, ”Glass-ceramic bodies and method of making them"
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External links
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