Transparent colored glass ceramic with good thermal stability and variable transmission in the IR region
AssigneeSchott Glaswerke
InventorsWolfgang Pannhorst, Erich Rodek, Herwig Scheidler
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Abstract
A transparent, colored glass ceramic containing high-quartz solid solution crystals, whose transmission in the IR range between 800 nm and 2.6 microns can be variably adjusted, and which has the composition (in weight percent) of 62-68% SiO.sub.2, 19.5-22.5% Al.sub.2 O.sub.3, 3.0-4.0 Li.sub.2 O, 1.5-3.5% BaO, 0.5-2.5% ZnO and 1.5-5.0% TiO.sub.2 in addition to other possible oxides, which are present in small quantities, the color being produced by MnO.sub.2, Fe.sub.2 O.sub.3, CoO, NiO, V.sub.2 O.sub.5 and Cr.sub.2 O.sub.3. This glass ceramic is transformed from the starting glass by a heat treatment between 680.degree. C. and 920.degree. C.
Claims13
A transparent, colored glass ceramic consisting essentially of high quartz solid solution crystals, especially suitable for the manufacture of heatable plates, wherein:
- a) the change in the linear thermal expansion coefficient has a positive value of not greater than 1.8.times.10.sup.-7 /.degree.K. over one to four heat treatment cycles of i) heating from room temperature at 4.degree. C./min to 720.degree. C.;
- ii) maintaining the temperature at 720.degree. C. for one hour, iii) heating at 2.degree. C./min to 880.degree. C., iv) maintaining the temperature at 880.degree. C. for 90 min, and v) cooling to room temperature;
- b) the change in the linear thermal expansion coefficient after one heat treatment cycle and tempering at 825.degree. C. for 35 hours has a positive value of not greater than 1.6.times.10.sup.-7 /.degree.K.;
- c) the transmission of the glass ceramic in the IR region between 800 nm and 2.6 microns can be variably adjusted;
- and
- d) the glass ceramic consists essentially of the following base glass composition (in weight percent):
- ______________________________________ SiO.sub.2 62-68 Al.sub.2 O.sub.3 19.5-22.5 Li.sub.2 O 3.0-4.0 Na.sub.2 O 0-1.0 K.sub.2 O 0-1.0 Na.sub.2 O + K.sub.2 O 0.5-1.5 BaO 1.5-3.5 CaO 0-1.0 BaO + CaO 1.5-4.0 MgO 0-0.5 ZnO 0.5-2.5 TiO.sub.2 2.0-2.8 ZrO.sub.2 0.0-3.0 TiO.sub.2 + ZrO.sub.2 3.5-5.5 MnO.sub.2 0.0-0.40 Fe.sub.2 O.sub.3 0.0-0.20 CoO 0.0-0.30 NiO 0.0-0.30 V.sub.2 O.sub.5 0.0-0.80 Cr.sub.2 O.sub.3 0.0-0.20 F 0.0-0.20 Sb.sub.2 O.sub.3 0.5-2.0 ______________________________________
- and wherein it was transformed from this glass-ceramic base glass by a heat treatment between 680.degree. C. and 920.degree. C.
A transparent, colored glass ceramic consisting essentially of high quartz solid solution crystals, especially suitable for the manufacture of heatable plates, wherein:
- a) the change in the linear thermal expansion coefficient has a positive value of not greater than 1.8.times.10.sup.-7 /.degree.K. over one to four heat treatment cycles of i) heating from room temperature at 4.degree. C./min to 720.degree. C.;
- ii) maintaining the temperature at 720.degree. C. for one hour, iii) heating at 2.degree. C./min to 880.degree. C., iv) maintaining the temperature at 880.degree. C. for 90 min, and v) cooling to room temperature;
- b) the change in the linear thermal expansion coefficient after one heat treatment cycle and tempering at 825.degree. C. for 35 hours has a positive value of not greater than 1.6.times.10.sup.-7 /.degree.K.;
- c) the transmission of the glass ceramic in the IR region between 800 nm and 2.6 microns can be variably adjusted;
- and
- d) the glass ceramic consists essentially of the following base glass composition (in weight percent):
- ______________________________________ SiO.sub.2 62-68 Al.sub.2 O.sub.3 19.5-22.5 Li.sub.2 O 3.0-4.0 Na.sub.2 O 0-1.0 K.sub.2 O 0-1.0 Na.sub.2 O + K.sub.2 O 0.5-1.5 BaO 1.5-3.5 CaO 0-1.0 BaO + CaO 1.5-4.0 MgO 0-0.5 ZnO 0.5-2.5 TiO.sub.2 1.5-5.0 ZrO.sub.2 0.0-3.0 TiO.sub.2 + ZrO.sub.2 3.5-5.5 MnO.sub.2 0.0-0.40 Fe.sub.2 O.sub.3 0.0-0.20 CoO 0.0-0.30 NiO 0.0-0.30 V.sub.2 O.sub.5 0.0-0.80 Cr.sub.2 O.sub.3 0.0-0.20 F 0.0-0.20 Sb.sub.2 O.sub.3 0.5-2.0 ______________________________________
- and wherein it was transformed from this glass-ceramic base glass by a heat treatment between 680.degree. C. and 920.degree. C.
Dependencies are inferred from the claim text.