CN1382662A

CN1382662A - Low-temp sinter process for squar-phase zirconium oxide polycrystal with stabilized nano yttrium oxide

Info

Publication number: CN1382662A
Application number: CN 02110868
Authority: CN
Inventors: 孙义海; 张玉峰; 郭景坤
Original assignee: Shanghai Institute of Ceramics of CAS
Current assignee: Shanghai Institute of Ceramics of CAS
Priority date: 2002-02-20
Filing date: 2002-02-20
Publication date: 2002-12-04
Anticipated expiration: 2022-02-20
Also published as: CN1169747C

Abstract

A low-temp sinter process for preparing nano yttrium oxide stabilized square-phase zirconium oxide polycrystal (Y-TZP) includes preparing additive from CaO, Al2O3 and SiO2 by glass fusing method, adding the additive (0.5-3 wt.%) to superfine Y-TZP powder, shaping, and sintering at 1350-1450 deg.C for 1-3 hr. Its advantages are 100 nm for grain size, high strength and toughness.

Description

The low-temperature sintering method of the tetragonal phase zirconium oxide polycrystalline material of stabilized nano yttrium oxide

Technical field

The present invention relates to a kind of nano zirconium oxide powder, low-temperature sintering utilized and obtain nano zircite crystal grain and high-strength and high ductility, Y ₂O ₃Content is tetragonal zirconia polycrystal body (Y-TZP) preparation methods of 1.5～3mol%, belongs to the structural ceramics field.

Background technology

The Y-TZP material is a kind of application structural ceramic material very widely.Because the effect of transformation toughening, it has intensity, hardness height, and good toughness, characteristics such as anticorrosive play an important role day by day in fields such as chemical industry, oil, machinery, electronics, communication and aerospace.But the present solid-phase sintering process (sintering temperature is 1550 ℃～1650 ℃) that widely adopts is big to equipment requirements height, loss because the sintering temperature height, has increased production cost greatly, has limited the widespread use of this kind material.

The processing of synthesizing nano Y-TZP material be meant its grain-size in 100 nanometers with interior material.By add certain additive in the Y-TZP powder, the change solid state sintering is liquid phase sintering, significantly the sinking sintering temperature and low.Prepare the processing of synthesizing nano Y-TZP material with low sintering method, can reduce the production cost of 2Y-TZP material, expand range of application.Simultaneously, since the low inhibition that reaches additive to grain growing of sintering temperature, nano zircite crystal grain, crystal grain is fully grown up in sintering process, the material that obtains behind the sintering, and its grain-size still is in nano level.Because crystal grain is little, the effect of refined crystalline strengthening makes this material have higher intensity.Therefore, the processing of synthesizing nano Y-TZP material that obtains of low-temperature sintering all has higher intensity.This preparation method is particularly useful for the preparation of 2Y-TZP material.2Y-TZP is a kind of as the Y-TZP material; because stablizer is few; under the solid state sintering condition; grain-size big (1～3 μ m), in the process of cooling after sintering process, regular meeting has some tetragonal phase zirconium oxides to be transformed into the monocline phase; the volumetric expansion of following in the phase transition process; material surface is cracked, serious even can advance to split, can not use as structured material basically.Therefore, about being used for structured material, the 2Y-TZP material rarely has report.Close grain makes the 2Y-TZP fully can be under constrained condition, at room temperature preserves and does not crack and advance to split.If it is suitable that grain size range is selected, the particle diameter of nanometer 2Y-TZP material is between the critical phase transformation size under the room temperature unconfined condition and room temperature have critical phase transformation size under the constraint condition, make tetragonal phase zirconium oxide remain to room temperature with metastable form, so, the toughness reinforcing effect of phase transformation enhancing is just still brought into play.Because the stabiliser content of 2Y-TZP is low, as long as tetragonal phase zirconium oxide can remain to room temperature, the effect of its transformation toughening just clearly.Therefore, nanometer 2Y-TZP material also has fracture toughness property preferably when having higher bending strength.

Summary of the invention

The object of the present invention is to provide a kind of low-temperature sintering method of processing of synthesizing nano Y-TZP material, the required production unit of this production technique is simple, and cost is low, be easy to realize suitability for industrialized production, and the processing of synthesizing nano Y-TZP material that obtains has good toughness characteristics such as crystal grain is little, intensity height.Be particularly useful for the 2Y-TZP material.

Low-temperature sintering provided by the invention, be glass powder by in the Y-TZP powder, adding calcium-aluminium-silicon series (CAS) as the sintering aid of liquid phase sintering, the add-on of CAS glass powder must be in certain scope, its add-on is 0.5～3% (quality).

Elaborate with regard to the preparation of sinter additives CAS powder and the preparation of Y-TZP material below.

1. sinter additives---the preparation of CAS powder

CAS powder as additive utilizes the preparation of melten glass method.Concrete steps are: with the certain mass ratio is 1: 3～5: 3～5 CaO, SiO ₂, and Al ₂O ₃Use zirconia ball, ball milling mixing 24h is incubated 4h down at 1500 ℃ then, after the fusion, at quenching-in water, obtains transparent CAS glass.CAS glass be crushed to certain size (＜1mm) after, put into ball grinding cylinder, with zirconia ball ball milling 72h.For preventing crystallization and improving mixing efficiency, all add deionized water in the mechanical milling process as dispersion medium.Oven dry after 120 mesh sieves sieve, promptly can be used as sintering aid and uses.CaO is with CaCO in the CAS glass powder ₃Form add.The add-on of CAS glass powder is vital to the sintering temperature that reduces the Y-TZP powder.It is obvious inadequately to be lower than 0.5% reduction temperature action, and is difficult to homodisperse; Surpass 3% (quality) sintering temperature is reduced, but the high-temperature behavior of performance, especially material is influenced, so be advisable to add 0.5～3% (quality), is preferably 1～2% (quality).

2. the preparation of processing of synthesizing nano Y-TZP material

The superfine Y-TZP powder that makes with known coprecipitation method is a raw material, (its meta particle diameter is 0.5～4 μ m), Y ₂O ₃Add-on be 1.5～3mol%, be additive with the CAS powder, the content of adding is 0.5～3wt% of Y-TZP powder, with zirconia ball and deionized water, wet-milling 24h.80 ℃ of oven dry down, after 120 orders sieve, add 1～3% (quality) PVA binding agent, add-on is to be that radix calculates with the Y-TZP powder, PVA is a pressed powder, adds fashionablely preferably to make 10% or be lower than 10% solution, water bath method earlier, add hydrothermal solution, add the PVA pressed powder more gradually, make it whole dissolvings, and don't can make solution temperature surpass 100 ℃, mixing, oven dry then sieved through 40 mesh sieves.The powder that mixes dry-pressing under 100MPa earlier, and then under 250MPa, wait static pressure.Last under different sintering temperatures sintering (1350 ℃～1450 ℃), and stove is chilled to room temperature after being incubated 1～3h.

The characteristics that low-temperature sintering legal system provided by the invention is equipped with nanometer high-strength and high ductility Y-TZP material are:

1. the grain-size of Zhi Bei processing of synthesizing nano Y-TZP material is in 60～120nm scope;

Production technique simple, to production unit require low, cost is low.Because only 1350～1450 ℃ of sintering temperatures are lower to the requirement of sintering oven furnace lining, and work-ing life of furnace lining and being prolonged, therefore production unit is required lowly, cost also is reduced;

3. the processing of synthesizing nano Y-TZP material that obtains has good comprehensive mechanical properties, intensity height, good toughness.Bending strength is 820～960MPa, Kic=9.5～9.8MPam ^1/2Be particularly suitable for low cost and prepare the superior 2Y-TZP material of over-all properties, be the condition created of applying of 2Y-TZP material.

Description of drawings

Fig. 1 is the X-ray diffractogram of the CAS additive of the present invention's preparation, does not have the obvious diffraction peak to occur among the figure, shows that under 1500 ℃ what obtain is the CAS glassy phase.

Fig. 2 is the stereoscan photograph of the nanometer 2Y-TZP material that makes with present method.

Fig. 3 is the polished surface of the nanometer 2Y-TZP material that makes with present method and the X-ray diffraction photo of fracture.Showing among the figure does not have the monocline phase zircite to exist on polished surface, illustrates because zirconic crystal grain makes tetragonal phase zirconium oxide can remain to room temperature fully.Being further illustrated among the figure has tangible monocline to exist mutually on the fracture, illustrate that the transformation toughening effect is the major cause that this material has higher toughness.

Embodiment further specifies embodiment and effect with following non-limiting enforcement example

Embodiment 1

In the 2Y-TZP powder that co-precipitation makes, be adding 1wt%CAS additive (CaO, Al ₂O ₃, SiO ₂Proportioning is 1: 4: 4), use ZrO ₂Ball and deionized water damp-warm syndrome 24 hours, 80 ℃ of oven dry, cross the choosing of 120 mesh sieves, add the 10% concentration PVA solution that is equivalent to 3%PVA dry powder amount, mixing oven dry, first 100MPa premolding, 250MPa moulding then, be incubated the 2Y-TZP material that obtained in 2 hours down at 1400 ℃, Fig. 2 is the photo of the scanning electron microscope of this material, and grain-size is about 80nm.Illustrate and adopt this kind method, can prepare nanometer 2Y-TZP material fully.After tested, the bending strength of this material is 900MPa, and fracture toughness property is 9.5MPam ^1/2, show that this material has good comprehensive mechanical properties.The photo (as shown in Figure 3) of the X diffraction of the polished surface of this material and fracture.

Embodiment 2

The add-on of sintering aid CAS powder is 2wt%, its CaO, Al ₂O ₃, SiO ₂Proportioning is 1: 3: 5, and the PVA add-on is 2%, 1350 ℃ of 3 hours sintering of insulation down.All the other conditions are with embodiment 1.After tested, the bending strength of this material is 820MPa, and fracture toughness property is 9.7MPam ^1/2

Embodiment 3

On the basis of embodiment 1, replace the 2Y-TZP powder with the 3Y-TZP powder, other conditions and example 1 are identical, and sintering obtains the 3Y-TZP material.The bending strength of this material is 965MPa.

Claims

1. the low-temperature sintering method of a processing of synthesizing nano Y-TZP material comprises that the preparation of the selection of additive and Y-TZP nanopowder is dry-pressing formed, it is characterized in that: Y ₂O ₃Stablizer is that the calcium-silicon-lead glass powder of the Y-TZP nanopowder adding 0.5～3% (quality) of 1.5～3mol% is a sinter additives, in 1350～1450 ℃, is incubated 1～3 hour.

2. by the low-temperature sintering method of the described processing of synthesizing nano Y-TZP material of claim 1, what it is characterized in that described sinter additives calcium-silicon-lead glass powder consists of CaO: SiO ₂: Al ₂O ₃=1: 3～5: 3～5 (mass ratio).

3,, it is characterized in that the meta particle diameter of the Y-TZP nanopowder of 1.5～3mol% is (0.5～4 μ m) by the low-temperature sintering method of the described processing of synthesizing nano Y-TZP material of claim 1.

4. by the low-temperature sintering method of the described processing of synthesizing nano Y-TZP material of claim 1, it is characterized in that described Y-TZP nanopowder is 2mol%Y ₂O ₃Stable Y-TZP powder.

5. by the low-temperature sintering method of the described processing of synthesizing nano Y-TZP material of claim 1, the add-on that it is characterized in that sinter additives CAS is 1～2% (quality).

6. by the low-temperature sintering method of claim 1 or 3 described processing of synthesizing nano Y-TZP materials, it is characterized in that the binding agent when dry-pressing formed is PVA, add-on is 1～3% (quality) of Y-TZP powder; After 100MPa premolding is adopted in dry-pressing, 200MPa isostatic pressing again.