Method for producing silicon carbide sintered body

Patent metadata

Field	Value
Publication number	US-11208357-B2
Application number	US-201815938223-A
Country	US
Kind code	B2
Filing date	Mar 28, 2018
Priority date	Mar 30, 2017
Publication date	Dec 28, 2021
Grant date	Dec 28, 2021

Abstract

A method for producing a silicon carbide sintered body, comprising adding water to a raw material mixture containing silicon carbide powder, at least one binder, and optionally at least one carbon source other than the silicon carbide and the at least one binder, and subjecting the raw material mixture to kneading, molding, and drying in this order, to obtain a dried body; heating the dried body to remove organic substances from the dried body to obtain a degreased body; and firing the degreased body in an inert atmosphere to obtain a silicon carbide sintered body. The method comprises controlling an expansion/shrinkage rate of the sintered body by adjusting at least one of (1) an amount of the at least one carbon source in the raw material mixture, (2) an amount of the at least one binder in the raw material mixture, and (3) a degreasing rate.

First claim

What is claimed is:

1. A method for producing a silicon carbide sintered body, comprising:
a step 1 of adding water to a raw material mixture containing silicon carbide powder, at least one binder, and optionally at least one carbon source other than the silicon carbide and the at least one binder, and subjecting the raw material mixture with water to kneading, molding, and drying in this order, to obtain a dried body;
a step 2 of heating the dried body obtained in the step 1 to remove organic substances from the dried body to obtain a degreased body; and
a step 3 of firing the degreased body obtained in the step 2 in an inert atmosphere to obtain a silicon carbide sintered body,
wherein the method comprises controlling an expansion rate and shrinkage rate of the sintered body in the step 3 by adjusting at least one selected from the group consisting of (1) an amount of the at least one carbon source other than the silicon carbide and the at least one binder in the raw material mixture, (2) an amount of the at least one binder in the raw material mixture, and (3) a degreasing rate in the step 2,
wherein the carbon concentration in the degreased body to be subjected to the step 3 is from 0.01 to 5.5% by mass.

2. The method according to claim 1 , wherein the method comprises controlling the expansion rate and shrinkage rate of the sintered body in the step 3 such that V2/V1 is from 0.91 to 1.13, in which V1 represents a volume of the dried body and V2 represents a volume of the sintered body.

3. The method according to claim 1 , wherein the method comprises controlling the expansion rate and shrinkage rate of the sintered body in the step 3 such that V2/V1 is from 0.91 to 1.00, in which V1 represents a volume of the dried body and V2 represents a volume of the sintered body.

4. The method according to claim 1 , wherein the method comprises controlling the expansion rate and shrinkage rate of the sintered body in the step 3 such that V2/V1 is from 1.00 to 1.13, in which V1 represents a volume of the dried body and V2 represents a volume of the sintered body.

5. The method according to claim 1 , wherein the method comprises controlling the expansion rate and shrinkage rate of the sintered body in the step 3 such that V2/V1 is from 0.999 to 1.001, in which V1 represents a volume of the dried body and V2 represents a volume of the sintered body.

6. The method according to claim 1 , wherein the method comprises adjusting the content of the at least one carbon source other than the silicon carbide and the at least one binder in the raw material mixture such that the content is in a range of from 0.06% by mass or more to less than 1% by mass, expressed in terms of carbon concentration.

7. The method according to claim 1 , wherein the method comprises adjusting the content of the at least one carbon source other than the silicon carbide and the at least one binder in the raw material mixture such that the content is less than 0.06% by mass, expressed in terms of carbon concentration.

8. The method according to claim 1 , wherein the method comprises adjusting the concentration of the at least one binder in the raw material mixture such that the concentration is in a range of from 2% by mass or more to 18% by mass or less.

9. The method according to claim 1 , wherein the method comprising adjusting the degreasing rate in the step 2 such that the degreasing rate is in a range of from 30 to 99%.

10. The method according to claim 1 , wherein the step 2 comprises heating the dried body at a temperature ranging from 300 to 600° C.

11. The method according to claim 1 , wherein the method comprises adjusting the amount of the at least one carbon source other than the silicon carbide and the at least one binder in the raw material mixture by adding one or more carbon sources selected from the group consisting of carbon black, pyrolytic graphite, expanded graphite, expandable graphite, and phenol resins.

12. The method according to claim 1 , wherein the step 1 comprises extrusion-molding the raw material mixture to obtain a columnar honeycomb formed body comprising a plurality of cells having flow paths penetrating from a first bottom surface to a second bottom surface, the plurality of cells being defined by partition walls.

13. The method according to claim 1 , wherein the firing in the step 3 is carried out while contacting the degreased body with metal silicon.

14. The method according to claim 1 , wherein the mean particle diameter of the at least one carbon source other than the silicon carbide and the at least one binder is more than 0.1 μm and 100 μm or less.

15. The method according to claim 1 , wherein the carbon concentration in the degreased body to be subjected to the step 3 is from 0.01 to 3.5% by mass.

Assignees

• Ngk Insulators Ltd

Inventors

• Ishida Hiroki
• Takahashi Hironori

Classifications

• C04B2235/424

  Carbon black · CPC title

• C04B2235/6581

  Total pressure below 1 atmosphere, e.g. vacuum · CPC title

• C04B35/638

  Removal thereof · CPC title

• C04B2235/606

  Drying · CPC title

• C04B2235/425

  Graphite · CPC title