Lithium-aluminosilicate glass ceramic with high keatite content and structural member made thereof
AssigneeSchott AG
InventorsThorsten Doehring, Ralf Jedamzik, Hauke Esemann, Eva Hoelzel, Ina Mitra
Life of this patent
Estimating the term…
Abstract
A lithium-aluminosilicate glass ceramic is transformed by a suitable heat treatment into a glass ceramic comprising at least 80 vol.-% of keatite mixed crystals. This may be utilized for the preparation of optical or mechanical high-precision parts having a high temperature resistance, a good stability and compatibility with components consisting of metals having a small coefficient of thermal expansion based on nickel and iron, such as Invar®.
Claims52
A method for the manufacture of a lithium-aluminosilicate glass ceramic comprising at least 70 vol.-% of keatite mixed crystals, the method comprising the following steps:
- casting a lithium-aluminosilicate base glass comprising
- (in wt.-%):
- 4 SiO2:
- 50-75 Al2O3:
- 17-30 Li2O:
- 2-8 B2O3:
- 0-5 P2O5:
- 0-15 SnO2 + ZrO2 + TiO2:
- 0.1-7 Na2O + K2O + Cs2O:
- 0-6 CaO + MgO + SrO + BaO + ZnO:
- 0-8 refining agents:
- 0-3 coloring oxides 0-5 and other oxides:
- into a mold;
- annealing the base glass for nucleation at a nucleation temperature of about 600 to 900° C.;
- annealing for keatite formation at a temperature of 800 to 1300° C., wherein the temperature and the duration of annealing for keatite formation is selected so as to yield a glass ceramic comprising at least 70 vol.-% of keatite mixed crystals and having a coefficient of thermal expansion between 1.5×10−6/K and 3×10−6/K in the range between 20° C. and 700° C.;
- and
- cooling to room temperature.
A method for the manufacture of a lithium-aluminosilicate glass ceramic comprising at least 70 vol.-% of keatite mixed crystals, the method comprising the following steps:
- casting a lithium-aluminosilicate base glass into a mold;
- annealing the base glass for nucleation at a nucleation temperature of about 600 to 900° C.;
- annealing for keatite formation at a temperature of 800 to 1300° C., wherein the temperature and the duration of annealing for keatite formation is selected so as to yield a glass ceramic comprising at least 70 vol.-% of keatite mixed crystals and having a coefficient of thermal expansion between 1.5×10−6/K and 3×10−6/K in the range between 20° C. and 700° C.;
- and
- cooling to room temperature.
A method for the manufacture of a lithium-aluminosilicate glass ceramic comprising keatite mixed crystals, the method comprising the following steps:
- casting a lithium-aluminosilicate base glass into a mold;
- annealing the base glass for nucleation at a nucleation temperature of about 600 to 900° C.;
- annealing for keatite formation at a temperature of 800 to 1300° C., wherein the temperature and the duration of annealing for keatite formation is selected so as to yield a glass ceramic comprising at least 50 vol.-% of keatite mixed crystals and having a coefficient of thermal expansion between 1.5×10−6/K and 3×10−6/K in the range between 20° C. and 700° C.;
- and
- cooling to room temperature.
A component made of a lithium-aluminosilicate glass ceramic comprising at least 70 vol.-%, of keatite mixed crystals, the coefficient of thermal expansion of the component being between 1.5×10−6/K and 3×10−6/K in the temperature range of 20° C. to 700° C.
A composite component comprising at least a first component of a lithium-aluminosilicate glass ceramic comprising at least 70 vol.-% of keatite mixed crystals and having a coefficient of thermal expansion between 1.5×10−6/K and 3×10−6/K in the range between 20° C. and 700° C., and further comprising at least a second component of an iron/nickel alloy having a coefficient of thermal expansion of 3×10−6/K at the most between 0° C. and 200° C.
A utilization of a lithium-aluminosilicate glass ceramic, comprising at least 80 vol.-% of keatite mixed crystals, for the preparation of mechanically fine machined high-precision parts.
Dependencies are inferred from the claim text.