Method of producing fired ceramic article and method of firing ceramic green body

Patent metadata

Field	Value
Publication number	US-11136272-B2
Application number	US-201816196057-A
Country	US
Kind code	B2
Filing date	Nov 20, 2018
Priority date	Jan 15, 2018
Publication date	Oct 5, 2021
Grant date	Oct 5, 2021

Abstract

The present disclosure is related to a method of producing a fired ceramic article. The method may include: heating a ceramic green body in a kiln, and controlling oxygen concentration in the kiln such that the oxygen concentration swings during the heating of the ceramic green body.

First claim

The invention claimed is:

1. A method of producing a fired ceramic article comprising:
heating a ceramic green body in a kiln at a temperature equal to or less than 300° C.; and
controlling oxygen concentration in the kiln such that the oxygen concentration swings during the heating of the ceramic green body, wherein
said controlling oxygen concentration in the kiln such that the oxygen concentration swings during the heating of the ceramic green body is performed based on fluctuating oxygen concentration of a gas supplied into the kiln.

2. The method of producing a fired ceramic article according to claim 1 , wherein said fluctuating oxygen concentration of a gas supplied into the kiln includes switching a gas supplied into the kiln at least between a first gas having a first oxygen concentration and a second gas having a second oxygen concentration that is lower than the first oxygen concentration.

3. The method of producing a fired ceramic article according to claim 2 , wherein the first oxygen concentration is equal to or less than 21 vol %.

4. The method of producing a fired ceramic article according to claim 3 , wherein the first oxygen concentration is equal to or less than 15 vol %.

5. The method of producing a fired ceramic article according to claim 2 , wherein the second oxygen concentration is equal to or less than 5 vol %.

6. The method of producing a fired ceramic article according to claim 1 , wherein said heating a ceramic green body in a kiln comprises:
first temperature-rising step, at a first temperature-rising rate, up to a target temperature in a temperature range over 180° C.; and
second temperature-rising step, at a second temperature-rising rate that is greater than the first temperature-rising rate, after the temperature in the kiln reached the target temperature.

7. The method of producing a fired ceramic article according to claim 6 , wherein said controlling oxygen concentration in the kiln such that the oxygen concentration swings during the heating of the ceramic green body is performed in said first temperature-rising step.

8. The method of producing a fired ceramic article according to claim 6 , wherein the target temperature is equal to or less than 300° C.

9. The method of producing a fired ceramic article according to claim 6 , wherein an atmosphere in the kiln is shifted from a low-oxygen atmosphere of less than 21 vol % to an air atmosphere synchronously when a temperature of the atmosphere in the kiln reaches the target temperature.

10. The method of producing a fired ceramic article according to claim 1 , wherein said controlling oxygen concentration in the kiln such that the oxygen concentration swings during the heating of the ceramic green body is performed when an atmosphere temperature in the kiln is equal to or less than 300° C.

11. The method of producing a fired ceramic article according to claim 1 , wherein the ceramic green body has a honeycombed structure built by cell-walls defining cells.

12. The method of producing a fired ceramic article according to claim 1 , wherein said fluctuating oxygen concentration of a gas supplied into the kiln includes repeating a cycle of supplying different gases having different oxygen concentrations into the kiln in a predetermined order.

13. A method of producing a fired ceramic article, comprising:
heating a ceramic green body in a kiln; and
controlling oxygen concentration in the kiln such that the oxygen concentration swings during the heating of the ceramic green body, wherein
said controlling oxygen concentration in the kiln such that the oxygen concentration swings during the heating of the ceramic green body is performed based on fluctuating oxygen concentration of a gas supplied into the kiln, and
wherein said fluctuating oxygen concentration of a gas supplied into the kiln includes repeating a cycle of alternately supplying into the kiln a first gas having a first oxygen concentration and a second gas having a second oxygen concentration that is lower than the first oxygen concentration.

14. The method of producing a fired ceramic article according to claim 13 , wherein the first oxygen concentration is equal to or less than 21 vol %.

15. The method of producing a fired ceramic article according to claim 14 , wherein the first oxygen concentration is equal to or less than 15 vol %.

16. The method of producing a fired ceramic article according to claim 13 , wherein the second oxygen concentration is equal to or less than 5 vol %.

17. The method of producing a fired ceramic article according to claim 13 , wherein a time period of supplying the first gas in one cycle is shorter than a time period of supplying the second gas in one cycle.

18. The method of producing a fired ceramic article according to claim 13 , wherein
3<((E+F)/R)<13 is satisfied, where
E represents a first supply amount calculated by multiplying the first oxygen concentration of the first gas and a time period of supplying the first gas in one cycle;
F represents a second supply amount calculated by multiplying the second oxygen concentration of the second gas and a time period of supplying the second gas in one cycle; and
R represents a time period of one cycle;
wherein oxygen concentration is in volume percent (vol %) and the time period is in any one of seconds, minutes, and hours.

Assignees

• Ngk Insulators Ltd

Inventors

• Kitaguchi Daniel Yukichi
• Tokunaga Takeshi

Classifications

• F27D2019/0068

  Regulation involving a measured inflow of a particular gas in the enclosure · CPC title

• F27D2019/0018

  Monitoring the temperature of the atmosphere of the kiln · CPC title

• F27D5/0031

  Treatment baskets for ceramic articles · CPC title

• C04B2235/6583

  Oxygen containing atmosphere, e.g. with changing oxygen pressures · CPC title

• F27D2007/063

  Special atmospheres, e.g. high pressure atmospheres · CPC title