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A zirconia ceramic

A zirconia ceramic, zirconia technology, applied in zirconia, inorganic chemistry, zirconium compounds, etc., can solve the problems of complex, expensive, unsuitable for large-scale production, etc.

Inactive Publication Date: 2007-09-19
ADVANCED NANO TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

With these prior art methods, powders still have to be pressed at relatively high pressures on the order of 400 MPa to obtain sinterable green bodies, thus limiting their application to very small articles
In addition to this problem, these techniques (especially pressure-assisted sintering) are inherently more complex and more expensive than conventional pressureless sintering in air, and are not suitable for large-scale production

Method used

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  • A zirconia ceramic
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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0089] Using ZrOCl as described in US Patent 6,203,768 2 .8H 2 Combination of mechanochemical treatment and precipitation of O and NaCl dilute phases produces multicomponent powders with a total cation molar ratio of Zr:Ce=91:9, the contents of which are incorporated herein by reference. to ZrOCl 2 .8H 2 O and NaCl were subjected to high-energy ball milling followed by heat treatment at a temperature of 750 °C, after which the diluted NaCl phase was removed by washing with water. The product of this first stage was a slurry of 12% by weight nano-sized zirconia particles suspended in water. The zirconia particles are kept in slurry form to avoid the formation of hard agglomerates that tend to form when the nano-sized zirconia particles are allowed to dry.

[0090] The average size of the nanosized zirconia particles in the slurry is about 20 nm, and has a relatively broad size distribution range of about 5-50 nm, as shown in Fig. 1(a). The BET surface area of ​​the nanosiz...

Embodiment 2

[0099] In the same manner as in Example 1, the multi-component powders with a total cation molar ratio Zr: Ce: Al: Fe of 88.8: 6: 4: 1.2 and 82.8: 12: 4: 1.2 were prepared, except that before the precipitation step Add appropriate amount of Al to the feed 2 Cl 4 (OH) 2 and FeCl 3 , and CeCl 3 .7H 2 O.

[0100] Figure 5 shows the thermal expansion curves of green bodies prepared by uniaxially pressing multi-component powders at 150 MPa. 9Ce-ZrO described in Example 1 2 Compared to the curves for the multicomponent powders (shown as dashed lines), it is clear that the multicomponent powders containing Al and Fe sinter at lower temperatures. The data also show that the sintering temperature increases with Ce content. Separate sintering experiments showed that a multicomponent powder containing 6% Ce, 4% Al and 1.2% Fe became substantially fully dense after sintering at 1120°C for 3 h, while at least 1150°C was required for the other two powders to become fully dense. The...

Embodiment 3

[0102] Prepare the multi-component powder with total cationic molar ratio Zr: Ce=70: 30 in the same manner as in Example 1, except that the powder containing 20% ​​CeO is used 2 zirconia powder instead of pure zirconia powder, adjust the CeCl added to the slurry before the precipitation step accordingly 3 .7H 2 O amount.

[0103] The green body obtained by uniaxial pressing at 150 MPa has 3.21 g / cm 3 density. After sintering at 1200 °C for 5 hours, the green body became almost completely dense (6.27 g / cm 3 ). The crystal structure of sintered zirconia ceramics is 100% cubic.

[0104] By comparison, a multicomponent powder prepared from pure zirconia particles (as in Example 1) with the same cation molar ratio Zr:Ce=70:30 could not be sintered to full density even at 1250°C because it contained too much more cerium hydroxide.

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Abstract

A multi-component powder for consolidation to form a sinterable green body for a zirconia ceramic is described. The multi-component powder comprises at least 80% by volume of nano-sized particles of zirconia and up to 20% by volume of a stabilising agent which may form a coating around the nano-sized particles of zirconia and is optionally in particulate form. A multi-component slurry formed by suspending the powder in a liquid is also described as well as a green body formed from either the slurry or the powder. A zirconia ceramic formed by sintering the green body is also described.

Description

field of invention [0001] The present invention relates to multicomponent powders for consolidation to form green bodies to be sintered into zirconia ceramics. The term "multicomponent powder" is used throughout this specification to describe a powder that is composed of two or more components, regardless of the manner in which they are distributed. [0002] The invention also relates to multicomponent slurries for the preparation of green bodies to be sintered into zirconia ceramics. [0003] The invention also relates to a green body for sintering zirconia ceramics formed by consolidation of multi-component powders and a method for producing the green body. [0004] The invention also relates to a zirconia ceramic formed by sintering the green body and a method of producing the zirconia ceramic. The present invention is particularly, but not exclusively, concerned with zirconia ceramics that are sintered to near full theoretical density at temperatures significantly lower ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01G25/02
CPCC04B35/6261C04B2235/3229C04B2235/765C04B2235/3217C04B2235/6567C04B35/486C04B2235/5472C04B2235/5454C04B2235/77C04B2235/608C04B2235/96C04B35/6455C04B2235/762C04B35/62892C04B2235/3272C04B35/4885C04B2235/3224B82Y30/00C01G25/00C04B2235/444C04B2235/9615C04B35/62615C04B35/488C01P2004/03C04B35/62815C01G25/02C04B35/62886C04B2235/02C04B2235/604C04B35/645C04B2235/656C01P2006/10C01P2004/64C01P2004/04C04B35/628C04B2235/3225C04B2235/3244C04B35/106B82B1/00
Inventor 室井道人G·J·特罗特
Owner ADVANCED NANO TECH
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