ZrO2-Al2O3-based ceramic sintered compact and production method thereof

Patent metadata

Field	Value
Publication number	US-9902654-B2
Application number	US-201615390088-A
Country	US
Kind code	B2
Filing date	Dec 23, 2016
Priority date	Jun 20, 2016
Publication date	Feb 27, 2018
Grant date	Feb 27, 2018

Abstract

A ZrO2—Al2O3-based ceramic sintered compact containing tetragonal ZrO2 particles having a crystallite size of from 5 to 20 nm as a main component and having an α-Al2O3 crystallite size of not greater than 75 nm and a relative density of not less than 99% can be produced by preparing a Y2O3 partially stabilized ZrO2—Al2O3-based powder having a molar ratio (mol %) of zirconia (ZrO2) and yttria (Y2O3) of from 96.5:3.5 to 97.5:2.5 and a mass ratio (mass %) of ZrO2 containing Y2O3 and alumina (Al2O3) of from 85:15 to 75:25, molding this powder by cold isostatic pressing, and then performing sintering to a high density by microwave sintering for 45 to 90 min in an inert gas atmosphere at 1200 to 1400° C. When performing microwave sintering, a heating rate is preferably from 5 to 20° C./min up to 600° C. and from 50 to 150° C./min at 600° C. or higher.

First claim

The invention claimed is:

1. A ZrO 2 —Al 2 O 3 -based ceramic sintered compact comprising a Y 2 O 3 partially stabilized ZrO 2 —Al 2 O 3 composite sintered compact having a molar ratio (mol %) of zirconia (ZrO 2 ) and yttria (Y 2 O 3 ) of from 96.5:3.5 to 97.5:2.5 and a mass ratio (mass %) of zirconia containing yttria and alumina (Al 2 O 3 ) of from 85:15 to 75:25; wherein the ZrO 2 —Al 2 O 3 composite sintered compact contains tetragonal ZrO 2 particles having a crystallite size of from 5 to 20 nm as a main component, a crystallite size of α-Al 2 O 3 is not greater than 75 nm; and the sintered compact has a relative density of not less than 99%.

2. The ZrO 2 —Al 2 O 3 -based ceramic sintered compact according to claim 1 , wherein a three-point bending strength is not less than 1.0 GPa; a fracture toughness is not less than 6.0 MPa·m 1/2 ; and a Vickers hardness H V is not less than 12.0 GPa.

3. A production method for a ZrO 2 —Al 2 O 3 -based ceramic sintered compact described in claim 1 , comprising the following steps:
(A): preparing a Y 2 O 3 partially stabilized ZrO 2 —Al 2 O 3 -based powder having a molar ratio (mol %) of zirconia (ZrO 2 ) and yttria (Y 2 O 3 ) of from 96.5:3.5 to 97.5:2.5 and a mass ratio (mass %) of zirconia containing yttria and alumina (Al 2 O 3 ) of from 85:15 to 75:25; and
(B): producing a high-density compact by molding the Y 2 O 3 partially stabilized ZrO 2 —Al 2 O 3 -based powder by cold isostatic pressing and then performing microwave sintering on the compact in an inert gas atmosphere at 1200 to 1400° C. for 45 to 90 min.

4. The method according to claim 3 , wherein a heating rate during performing microwave sintering in (B) is from 5 to 20° C./min up to 600° C. and from 50 to 150° C./min at 600° C. or higher.

5. The method according to claim 3 , wherein a mixture of a Y 2 O 3 partially stabilized ZrO 2 and an Al 2 O 3 powder or a solid solution powder produced by a coprecipitation process is used as the Y 2 O 3 partially stabilized ZrO 2 —Al 2 O 3 -based powder.

6. A production method for a ZrO 2 —Al 2 O 3 -based ceramic sintered compact described in claim 2 , comprising the following steps:
(A): preparing a Y 2 O 3 partially stabilized ZrO 2 —Al 2 O 3 -based powder having a molar ratio (mol %) of zirconia (ZrO 2 ) and yttria (Y 2 O 3 ) of from 96.5:3.5 to 97.5:2.5 and a mass ratio (mass %) of zirconia containing yttria and alumina (Al 2 O 3 ) of from 85:15 to 75:25; and
(B): producing a high-density compact by molding the Y 2 O 3 partially stabilized ZrO 2 —Al 2 O 3 -based powder by cold isostatic pressing and then performing microwave sintering on the compact in an inert gas atmosphere at 1200 to 1400° C. for 45 to 90 min.

7. The method according to claim 4 , wherein a mixture of a Y 2 O 3 partially stabilized ZrO 2 and an Al 2 O 3 powder or a solid solution powder produced by a coprecipitation process is used as the Y 2 O 3 partially stabilized ZrO 2 —Al 2 O 3 -based powder.

Assignees

• The Doshisha
• Daiichi Kigenso Kagaku Kogyo

Inventors

• Hirota Ken
• Ge Xiaoteng
• Kimura Hideo

Classifications

• C04B2235/3246

  Stabilised zirconias, e.g. YSZ or cerium stabilised zirconia · CPC title

• C04B2235/6562

  Heating rate · CPC title

• C04B2235/667

  Sintering using wave energy, e.g. microwave sintering · CPC title

• C04B2235/3225

  Yttrium oxide or oxide-forming salts thereof · CPC title

• C04B2235/765

  Tetragonal symmetry · CPC title