Negative thermal expansion glass ceramic and method for producing the same

• US 6,506,699 B1
• Filed: 10/15/1999
• Issued: 01/14/2003
• Est. Priority Date: 10/23/1998
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Ohara
• Original Assignee: Kabushiki Kaisha Ohara
• Inventors: Shindo, Ayako, Goto, Naoyuki
• Primary Examiner(s): GROUP, KARL E
• Application Number:
  US09/418,754
• Time in Patent Office: 1,187 Days
• Field of Search: 501/4, 501/7, 65/338
• US Class Current: 501/7
• 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 (β-SiO₂ 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 produced by subjecting a base glass to a heat treatment,

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

2. The negative thermal expansion glass ceramic of claim 1, comprising a main crystalline phase which is at least one crystalline phase selected from the group consisting of β

-eucryptite solid solution, β

-eucryptite, β

-quartz solid solution, and β

-quartz.

3. The negative thermal expansion glass ceramic of claim 1, wherein a total amount of crystals of the main crystalline phases is from 70 to 100 mass percent.

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

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

8. The negative thermal expansion glass ceramic according to claim 5, wherein the formed glass is annealed after forming the molten glass and before heating the formed product.

10. The negative thermal expansion glass ceramic of claim 1, comprising from 0 to less than 4 mass percent of ZrO₂.

6. 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 a powder;

forming the powder into a product; and

firing the formed product at a temperature range of 1200°

C. to 1350°

C. to crystallize the product, the product having a coefficient of thermal expansion of from −

25 to −

100×

10<sup>−

7</sup>/°

C. in the temperature range of from −

40°

C. to =160°

C.;

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

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

melting a base glass to form a molten base glass;

forming the molten base glass into a product;

heat treating the formed product at a temperature range of 620°

C. to 800°

C. to nucleate the product; and

heat treating the resulting product at a temperature range of 700°

C. to 950°

C. to crystallize the product, the product having a coefficient of thermal expansion of from −

25 to −

100×

10<sup>−

7</sup>/°

C. in the temperature range of from −

40°

C. to =160°

C.;

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

9. The method for producing a negative thermal expansion glass ceramic according to claim 7, further comprising annealing the formed base glass, after forming the molten base glass and before subjecting the formed product to the heat treatment.