Negative thermal expansion glass ceramic

• US 20020045527A1
• Filed: 10/11/2001
• Published: 04/18/2002
• Est. Priority Date: 10/23/1998
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Ohara
• Original Assignee: Kabushiki Kaisha Ohara
• Inventors: Shindo, Ayako, Goto, Naoyuki
• Granted Patent: US 6,521,556 B2
• Time in Patent Office: Days
• US Class Current: 501/4
• CPC Class Codes: C03C 10/0027 containing SiO2, Al2O3, Li2O as main constituents
• CPC Class Codes: G02B 6/0218 using mounting means, e.g. by using a combination of materials having different thermal expansion coefficients
• CPC Class Codes: G02B 6/3854 Ferrules characterised by materials

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.

Claims

1. A negative thermal expansion glass ceramic having a coefficient of thermal expansion of −

25 to −

100×

10<sup>−

7</sup>/°

C. in a temperature range of −

40°

C. to +160°

C.

2. The negative thermal expansion glass ceramic as claimed in claim 1, comprising main crystalline phases which are one or more types selected from a group consisting of β

-eucryptite solid solution, β

-eucryptite, β

-quartz solid solution, and β

-quartz.

3. The negative thermal expansion glass ceramic as claimed in claim 2, wherein a total amount of crystals of the main crystalline phases are 70 to 100% in mass percent.

4. The negative thermal expansion glass ceramic as claimed in claim 1, wherein the glass ceramic is produced by subjecting a base glass to a heat treatment,

wherein the base glass comprises, in mass percent, the following components:

SiO₂40-65%Al₂O₃25-45%Li₂O 

5-15%B₂O₃0-3%BaO0.5-4% 

 

MgO0-2%CaO0-3%ZnO0-6%P₂O₅0-4%ZrO₂0-4%TiO₂0-4%As₂O₃ + Sb₂O₃0-2%

and the base glass is essentially free of PbO, Na₂O, and K₂O.

5. The negative thermal expansion glass ceramic as claimed in claim 1, wherein the glass ceramic is produced by melting a base glass, quenching the molten glass, reducing the quenched glass to powders to form, and firing the formed product to crystallize,

wherein the base glass comprises, in mass percent, the following components:

SiO₂40-65%Al₂O₃25-45%Li₂O 

5-15%B₂O₃0-3%BaO0.5-4% 

 

MgO0-2%CaO0-3%ZnO0-6%P₂O₅0-4%ZrO₂0-4%TiO₂0-4%As₂O₃ + Sb₂O₃0-2%

and the base glass is essentially free of PbO, Na₂O, and K₂O.

6. The negative thermal expansion glass ceramic as claimed in claim 1, wherein the glass ceramic is produced by melting a base glass, forming the molten glass, annealing the formed glass as needed, and heating the formed product to crystallize,

wherein the base glass comprises, in mass percent, the following components:

SiO₂40-65%Al₂O₃25-45%Li₂O 

5-15%B₂O₃0-3%BaO0.5-4% 

 

MgO0-2%CaO0-3%ZnO0-6%P₂O₅0-4%ZrO₂0-4%TiO₂0-4%As₂O₃ + Sb₂O₃0-2%

and the base glass is essentially free of PbO, Na₂O, and K₂O.

9. The negative thermal expansion glass ceramic as claimed in claim 1, wherein the glass ceramic is a material having little anisotropy.

10. The negative thermal expansion glass ceramic as claimed in claim 1, wherein the glass ceramic is applied to a temperature compensating member, with combined with a material having a positive coefficient of thermal expansion.

11. The negative thermal expansion glass ceramic as claimed in claim 1, wherein the glass ceramic is applied to a device securing an optical fiber.

7. A method for producing a negative thermal expansion glass ceramic, comprising the steps of:

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;

SiO₂40-65%Al₂O₃25-45%Li₂O 

5-15%B₂O₃0-3%BaO0.5-4% 

 

MgO0-2%CaO0-3%ZnO0-6%P₂O₅0-4%ZrO₂0-4%TiO₂0-4%As₂O₃ + Sb₂O₃0-2%

and the base glass is essentially free of PbO, Na₂O, and K₂O.

8. A method for producing a negative thermal expansion glass ceramic, comprising the steps of:

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;

SiO₂40-65%Al₂O₃25-45%Li₂O 

5-15%B₂O₃0-3%BaO0.5-4% 

 

MgO0-2%CaO0-3%ZnO0-6%P₂O₅0-4%ZrO₂0-4%TiO₂0-4%As₂O₃ + Sb₂O₃0-2%

and the base glass is essentially free of PbO, Na₂O, and K₂O.