Stock material or miscellaneous articles – Composite – Of quartz or glass
Reexamination Certificate
2005-04-05
2005-04-05
Jones, Deborah (Department: 1775)
Stock material or miscellaneous articles
Composite
Of quartz or glass
C428S689000, C428S697000, C106S286400, C106S286600
Reexamination Certificate
active
06875515
ABSTRACT:
A fused quartz article, such as a muffle tube or crucible, with enhanced creep resistance. The enhanced creep resistance is the result of controlled devitrification of the fused quartz article. Controlled devitrification is achieved by coating the article with a colloidal silica slurry doped with metal cations, such as barium, strontium, and calcium. The metal cations in the slurry promote nucleation and growth of cristobalite crystals into the fused quartz at temperatures in the range from about 1000° C. to about 1600° C. The cristobalite has significantly higher viscosity, and therefore greater creep resistance at elevated temperatures, than fused quartz. Methods for applying a doped coating to a fused quartz article and improving the creep resistance of a fused quartz article are also disclosed.
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Journal of the American Ceramic Society,Devitrification of High-SiO2Glasses of the System Al2O3-SiO2SD Brown et al., vol. 42, No. 6, pp 263-270, Jun. 1, 1959.
Translated from Fizika I Khimiya Stekla, “Combined Effect of Impurity Oxides of Alkali Metals and Aluminum On the Viscosity of Vitreous Silica”, vol. 6, No. 5, pp 553-557, Sep.-Oct. 1980. Original article submitted Feb. 22, 1980.
PCT Search Report.
Ahlgren Frederic Francis
Giddings Robert Arthur
Lou Victor Lien-Kong
McNulty Thomas Francis
Pender David Charles
Blackwell-Rudasill G.
Caruso Andrew J.
Jones Deborah
Patnode Patrick K.
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