Controlling Of Sintering Kinetics Of Oxide Ceramics

Patent metadata

Field	Value
Publication number	US-2016157971-A1
Application number	US-201414906045-A
Country	US
Kind code	A1
Filing date	Jul 21, 2014
Priority date	Jul 22, 2013
Publication date	Jun 9, 2016
Grant date	—

Abstract

The invention relates to multi-layer oxide ceramic bodies and in particular to presintered multi-layer oxide ceramic blanks and oxide ceramic green bodies suitable for dental applications. These bodies can be thermally densified by further sintering without distortion and are thus particularly suitable for the manufacture of dental restorations. The invention also relates to a process for the manufacture of such multi-layer oxide ceramic bodies as well as to a process for the manufacture of dental restorations using the multi-layer oxide ceramic bodies.

First claim

1 . Presintered multi-layer oxide ceramic blank for the manufacture of dental restorations comprising at least two different layers and having a coefficient of distortion

d
=

(

H




V
max

-

H




V
min

)

H



V

_

of less than 0.4, which coefficient is calculated on the basis of at least one measurement of HV 2.5 for each of the different layers,
wherein:
HV 2.5 is the Vickers hardness measured at a load of 2.5 kgf (24.517 N) according to ISO 14705:2008;
HV max is the maximum of the measured values of HV 2.5 ;
HV min is the minimum of the measured values of HV 2.5 ; and
HV is the arithmetic mean of the measured values of HV 2.5 .

2 . Blank according to claim 1 which is suitable for the manufacture of a multi-unit dental restoration.

3 . Blank according to claim 1 , wherein the at least two different layers differ in terms of chemical composition.

4 . Blank according to claim 1 , wherein the oxide ceramic is based on zirconia.

5 . Blank according to claim 1 , wherein the coefficient of distortion is calculated on the basis of measurements of HV 2.5 at measuring points which are distributed at a constant distance along a first line intercepting the different layers on an outer surface of the blank.

6 . Blank according to claim 35 , wherein the constant distance between the measuring points along the first and second lines is not more than 5 mm.

7 . Multi-layer oxide ceramic green body for the manufacture of dental restorations comprising at least two different layers and having a coefficient of distortion

d
=

(

H




V
max

-

H




V
min

)

H



V

_

of less than 0.4, which coefficient is calculated on the basis of at least one measurement of HV 2.5 for each of the different layers, after a sintering step at a temperature in the range of 850 to 1350° C.,
wherein:
HV 2.5 is the Vickers hardness measured at a load of 2.5 kgf (24.517 N) according to ISO 14705:2008;
HV max is the maximum of the measured values of HV 2.5 ;
HV min is the minimum of the measured values of HV 2.5 ; and
HV is the arithmetic mean of the measured values of HV 2.5 .

8 . Multi-layer oxide ceramic body for the manufacture of dental restorations comprising at least two different layers, wherein a sintering behavior of the at least two different layers is aligned to allow the ceramic body to be sintered without distortion.

9 . Process for the manufacture of a multi-layer oxide ceramic body having at least two different layers which body can be sintered without distortion, wherein the process comprises aligning a sintering behavior of the different layers.

10 . Process according to claim 9 , wherein the body is suitable for the manufacture of a multi-unit dental restoration.

11 . Process according to claim 9 , wherein the at least two different layers differ in terms of chemical composition.

12 . Process according to claim 9 , which process comprises
(a) providing at least a first oxide ceramic material and a second oxide ceramic material, wherein the first oxide ceramic material and the second oxide ceramic material differ in terms of a sintering behavior; and (b) adapting at least one of the oxide ceramic materials to align the sintering behavior of the first oxide ceramic material to the sintering behavior of the second oxide ceramic material.

13 . Process according to claim 12 , wherein the sintering behavior is the relative linear shrinkage upon sintering at a temperature in the range of 850 to 1350° C.

14 . Process according to claim 12 , wherein in step (a) the sintering behavior of the first oxide ceramic material and the sintering behavior of the second oxide ceramic material differ by at least 0.15%.

15 . Process according to claim 12 , wherein in step (b) the adapting results in the sintering behavior of the first oxide ceramic material and the sintering behavior of the second oxide ceramic material differing by less than 0.15%.

16 . Process according to claim 12 which further comprises
(c) forming layers of the oxide ceramic materials and arranging the layers on top of one another or forming a layer of the oxide ceramic materials which comprises a continuous gradient from the first oxide ceramic material to the second oxide ceramic material;
(d) optionally compacting the oxide ceramic materials to obtain a green body; and
(e) optionally presintering the oxide ceramic materials to obtain a presintered ceramic blank.

17 . Process according to claim 12 , wherein adapting at least one of the oxide ceramic materials comprises incorporating a dopant into said oxide ceramic material.

18 . Process according to claim 17 , wherein said dopant is selected from sintering aids, and sintering inhibitors.

19 . Process according to claim 12 , wherein adapting at least one of the oxide ceramic materials comprises changing at least one of the primary particle size, the secondary particle size or the specific surface area of at least a portion of said oxide ceramic material.

20 . Process according to claim 12 , wherein adapting at least one of the oxide ceramic materials comprises subjecting said oxide ceramic materials to different degrees of partial densification.

21 . Multi-layer oxide ceramic body obtainable by the process

Assignees

• Ivoclar Vivadent Ag

Inventors

• Rothbrust Frank
• Ritzberger Christian
• Brodkin Dmitri
• Khan Ajmal
• Schweiger Marcel

Classifications

• A61K6/61

  Cationic, anionic or redox initiators · CPC title

• C04B2237/58

  Forming a gradient in composition or in properties across the laminate or the joined articles · CPC title

• C04B2235/604

  Pressing at temperatures other than sintering temperatures · CPC title

• C04B35/486

  Fine ceramics · CPC title

• C04B2235/3217

  Aluminum oxide or oxide forming salts thereof, e.g. bauxite, alpha-alumina · CPC title