Translucent zirconia sintered body and zirconia powder, and use therefor

Patent metadata

Field	Value
Publication number	US-9737383-B2
Application number	US-201415104036-A
Country	US
Kind code	B2
Filing date	Dec 19, 2014
Priority date	Dec 24, 2013
Publication date	Aug 22, 2017
Grant date	Aug 22, 2017

Abstract

To provide a zirconia sintered body having both excellent translucency and bending strength, specifically a zirconia sintered body having both translucency and strength suitable as a denture for front tooth, and a process for its production.
A translucent zirconia sintered body containing more than 4.0 mol % and at most 6.5 mol % of yttria and less than 0.1 wt % of alumina, and having a relative density of at least 99.82%, a total light transmittance of at least 37% and less than 40% to light with a wavelength of 600 nm at a thickness of 1.0 mm, and a bending strength of at least 500 MPa, and a process for its production.

First claim

The invention claimed is:

1. A translucent zirconia sintered body containing more than 4.0 mol % and at most 6.5 mol % of yttria and less than 0.1 wt % of alumina, and having a relative density of at least 99.82%, a total light transmittance of at least 37% and less than 40% to light with a wavelength of 600 nm at a thickness of 1.0 mm, a crystal grain size of from 0.3 to 1.0 μm, and a bending strength of at least 500 MPa.

2. The translucent zirconia sintered body according to claim 1 , wherein a ratio of total light transmittance to D65 light at a sample thickness of 1.0 mm, to total light transmittance to light with a wavelength of 600 nm at a sample thickness of 1.0 mm, is at least 1.16.

3. A process for producing a translucent zirconia sintered body as defined in claim 1 , comprising molding a zirconia powder containing more than 4.0 mol % and at most 6.5 mol % of yttria and less than 0.1 wt % of alumina, to obtain a green body, and sintering the green body under normal pressure at a sintering temperature of from 1,350° C. to 1,500° C.

4. The process according to claim 3 , wherein the density of the green body is more than 3.2 g/cm 3 .

5. A zirconia powder containing more than 4.0 mol % and at most 6.5 mol % of yttria and less than 0.1 wt % of alumina, and having a crystallite size of from 320 to 380 Å, and a BET specific surface area of from 8 to 15 m 2 /g.

6. The zirconia powder according to claim 5 , having an average particle size of from 0.40 to 0.50 μm.

7. The zirconia powder according to claim 5 , wherein the total proportion of tetragonal and cubic contained in the crystal is at least 80%.

8. The zirconia powder according to claim 5 , further containing an organic binder.

9. The zirconia powder according to claim 5 , wherein the zirconia powder is spray molded powder granules.

10. A method for producing a zirconia sintered body, comprising forming a body from the zirconia powder as defined in claim 5 , and sintering the formed body.

11. A dental material comprising the translucent zirconia sintered body as defined in claim 1 .

12. The dental material according to claim 11 , which is a denture, a denture mill blank, a denture for front tooth, a denture mill blank for front tooth, or an orthodontic bracket.

13. A process for producing a translucent zirconia sintered body containing more than 4.0 mol % and at most 6.5 mol % of yttria and less than 0.1 wt % of alumina, and having a relative density of at least 99.82%, a total light transmittance of at least 37% and less than 40% to light with a wavelength of 600 nm at a thickness of 1.0 mm, and a bending strength of at least 500 MPa, the process comprising molding a zirconia powder containing more than 4.0 mol % and at most 6.5 mol % of yttria and less than 0.1 wt % of alumina, to obtain a green body having a density of more than 3.2 g/cm 3 , and sintering the green body under normal pressure at a sintering temperature of from 1,350° C. to 1,500° C.

Assignees

• Tosoh Corp

Inventors

• Fujisaki Hiroyuki
• Kawamura Kiyotaka

Classifications

• A61K6/818

  comprising zirconium oxide · CPC title

• C01P2002/76

  by a space-group or by other symmetry indications · CPC title

• C04B2235/96

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

• A61C7/14 Primary

  Brackets (A61C7/28 takes precedence); Fixing brackets to teeth · CPC title

• C01P2004/61

  Micrometer sized, i.e. from 1-100 micrometer · CPC title