Process for forming sintered ceramic bodies having improved properties

Patent metadata

Field	Value
Publication number	US-12077477-B2
Application number	US-202117503459-A
Country	US
Kind code	B2
Filing date	Oct 18, 2021
Priority date	Oct 31, 2017
Publication date	Sep 3, 2024
Grant date	Sep 3, 2024

Abstract

A method is provided for making ceramic bodies having improved properties, such as optical and/or strength properties in which the ceramic bodies are densified by new sintering processes. The sintering profiles may have shorter run times than conventional sintering processes. Ceramic bodies made by these methods are suitable for use in dental applications, for example, as crowns.

First claim

We claim:

1. A method for forming a sintered ceramic body comprising
heating a bisque stage ceramic body in a heating chamber of a sintering oven, comprising
i. in a first heating stage, heating the sintering oven to a first temperature that is from 1200° C. to 1500° C. for an optional first dwell time that is from 0 minutes to 180 minutes, and raising the first temperature by 50° C. to 500° C. to a second temperature between 1400° C. and 1700° C.;
ii. in a second heating stage, holding the second temperature for a second dwell time of between 0 minutes and 20 minutes;
iii. a third heating stage wherein the second temperature is decreased between 50° C. and 200° C. to a third temperature for a dwell time of about 0 minutes to 120 minutes; and
iv. a fourth heating stage wherein the third temperature is increased between 100° C. and 800° C. to a fourth temperature for a dwell time of about 0 minutes to about 5 minutes.

2. The method of claim 1 , wherein the first heating stage has a ramp rate of 0.5° C./minute to 60° C./minutes from the first heating temperature to the second temperature.

3. The method of claim 1 , wherein the first temperature is from 1350° C. to 1500° C.

4. The method of claim 1 , wherein the first dwell time is from 15 minutes to 180 minutes.

5. The method of claim 1 , wherein the first temperature is from 50° C. to 200° C. lower than the second temperature.

6. The method of claim 1 , wherein the first temperature is from 300° C. to 500° C. lower than the second temperature.

7. The method of claim 1 , wherein the second temperature is from 1530° C. to 1600° C.

8. The method of claim 1 , wherein
i. the first temperature is from 1350° C. to 1500° C. and the first dwell time is from 15 minutes to 180 minutes, and
ii. the second temperature is from 1530° C. to 1600° C. and the second dwell time is from 0 minutes to 20 minutes.

9. The method of claim 1 , wherein the sintering oven is heated to the first temperature from a preliminary heating temperature that is lower than the first temperature, and the preliminary heating temperature is from 1000° C. to 1450° C.

10. The method of claim 1 , wherein the third temperature is 1200° C.

11. The method of claim 1 , wherein the fourth temperature is between 1600° C. and 1800° C.

12. The method of claim 1 , wherein the ceramic body comprises yttria-stabilized zirconia stabilized comprising from 2 mol % to 8 mol % yttria.

13. The method of claim 10 , wherein the ceramic body comprises yttria-stabilized zirconia stabilized comprising from 2 mol % to 8 mol % yttria.

14. The method of claim 11 , wherein the ceramic body comprises yttria-stabilized zirconia stabilized comprising from 2 mol % to 8 mol % yttria.

Assignees

• Glidewell James R Dental Ceramics Inc

Inventors

• Balasubramanian Sreeram
• Yang Yan
• Akash

Classifications

• A61C13/0022

  Blanks or green, unfinished dental restoration parts · CPC title

• C04B2235/6027

  Slip casting · CPC title

• C04B35/486

  Fine ceramics · CPC title

• C04B2235/96

  Properties of ceramic products, e.g. mechanical properties such as strength, toughness, wear resistance · CPC title

• C04B2235/785

  Submicron sized grains, i.e. from 0,1 to 1 micron · CPC title