Negative thermal expansion glass ceramic
First Claim
1. A negative thermal expansion glass ceramic having a coefficient of thermal expansion of −
- 25 to −
100×
10−
7/°
C. in a temperature range of −
40°
C. to +160°
C.
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Abstract
A negative thermal expansion glass ceramic having a negative coefficient of thermal expansion, which is a sufficiently large absolute value in a temperature range of −40° C. to +160° C. and a method for producing the same are provided. The negative thermal expansion glass ceramic has a coefficient of thermal expansion of −25 to −100×10−7/° C. in the temperature range of −40° C. to +160° C., and comprises main crystalline phases which are one or more types selected from a group consisting of β-eucryptite solid solution (β-Li2O.Al2O3.2SiO2 solid solution), β-eucryptite (β-Li2O.Al2O3.2SiO2), β-quartz solid solution (βSiO2 solid solution), and β-quartz (β-SiO2), wherein a total amount of crystals of the main crystalline phases can be 70 to 100% in mass percent.
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Citations
11 Claims
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1. A negative thermal expansion glass ceramic having a coefficient of thermal expansion of −
- 25 to −
100×
10−
7/°
C. in a temperature range of −
40°
C. to +160°
C. - View Dependent Claims (2, 3, 4, 5, 6, 9, 10, 11)
- 25 to −
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7. A method for producing a negative thermal expansion glass ceramic, comprising the steps of:
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melting a base glass;
quenching the molten base glass;
reducing the quenched base glass to powders to form; and
firing the formed product at a temperature range of 1200°
C. to 1350°
C. to crystallize;
wherein the base glass comprises, in mass percent, the following components;
SiO2 40-65% Al2O3 25-45% Li2O
5-15%B2O3 0-3% BaO 0.5-4%
MgO 0-2% CaO 0-3% ZnO 0-6% P2O5 0-4% ZrO2 0-4% TiO2 0-4% As2O3 + Sb2O3 0-2% and the base glass is essentially free of PbO, Na2O, and K2O.
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8. A method for producing a negative thermal expansion glass ceramic, comprising the steps of:
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melting a base glass;
forming the molten base glass;
annealing the formed base glass as needed;
subjecting the formed product to a heat treatment at a temperature range of 620°
C. to 800°
C. to nucleate; and
subjecting the resulting product to a heat treatment at a temperature range of 700°
C. to 950°
C. to crystallize;
wherein the base glass comprises, in mass percent, the following components;
SiO2 40-65% Al2O3 25-45% Li2O
5-15%B2O3 0-3% BaO 0.5-4%
MgO 0-2% CaO 0-3% ZnO 0-6% P2O5 0-4% ZrO2 0-4% TiO2 0-4% As2O3 + Sb2O3 0-2% and the base glass is essentially free of PbO, Na2O, and K2O.
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Specification