Compositions: ceramic – Ceramic compositions – Refractory
Reexamination Certificate
2008-02-06
2009-06-02
Group, Karl E (Department: 1793)
Compositions: ceramic
Ceramic compositions
Refractory
C065S374130, C065S195000
Reexamination Certificate
active
07541304
ABSTRACT:
Isopipes for use in making sheet glass by a fusion process are provided which exhibit reduced sag. The isopipes are composed of a zircon refractory which has a mean creep rate (MCR) at 1180° C. and 250 psi and a 95 percent confidence band (CB) for said mean creep rate such that the CB to MCR ratio is less than 0.5, the MCR and the CB both being determined using a power law model. The zircon refractory can contain titania (TiO2) at a concentration greater than 0.2 wt. % and less than 0.4 wt. %. A concentration of titania in this range causes the zircon refractory to exhibit a lower mean creep rate than zircon refractories previously used to make isopipes. In addition, the variation in mean creep rate is also reduced which reduces the chances that the zircon refractory of a particular isopipe will have an abnormally high creep rate and thus exhibit unacceptable sag prematurely.
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Helfinstine John D.
Liebner Daniel J.
Martin John L.
Neubauer Dean V.
Powell William R.
Corning Incorporated
Group Karl E
Klee Maurice M.
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