JPH01294531A - Production of thin film of stabilized zirconia - Google Patents

Abstract

PURPOSE:To obtain a dense thin film of zirconia stabilized with yttria fast stuck to a substrate, having high uniformity by coating the substrate with a slurry containing plural kinds of zirconia particles stabilized with yttria having limited particles diameters and a binder, drying and burning. CONSTITUTION:Zirconia particles stabilized with yttria, having 1-5mu particle diameter are blended with zirconia particles stabilized with yttria, having <=1mu particle diameters and two or groups of different diameters and a binder to form a slurry. Then the slurry is applied to a substrate, dried and burnt to give the aimed thin film. In this method, when the raw material particles having the above-mentioned particle diameters are blended and packed, the particles are made into a state wherein a small amount of the particles having <=1mu particle diameter are packed into gaps of a large amount of the particles having 1-5mu particle diameter. When the resulting particles are sintered, since the particles having <=1mu particle diameter are melted at a lower temperature than the particles having 1-5mu particle diameter and act like a binder, melting of mixed particles of raw materials is not required and sintering can be carried out at low temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing an ittria-stabilized zirconia film in close contact with a substrate for use as an electrode material, electronic material, or the like.

[Conventional technology]

Conventionally, a well-known method for manufacturing ceramic ceramics is the so-called doctor blade method, in which oxide powder, a binder, and a dispersion medium are kneaded, flatly shaped, dried, and fired.

[Problem to be solved by the invention]

However, the membrane of rear-stabilized ziconium (fully stabilized type) manufactured by the conventional doctor blade method is paper-like when used as a thin film alone, and is brittle due to its low toughness, and does not adhere to the surface of the substrate. It is difficult to support the membrane, and if the membrane thickness is increased in an attempt to increase the strength, the membrane performance deteriorates.

In view of the above-mentioned state of the art, the present invention does not have the disadvantages of ittria-stabilized zirconia obtained by conventional methods, and
The present invention aims to provide a method for manufacturing a dense and highly uniform ittria-stabilized zirconia thin film that adheres to a substrate.

[Means to solve the problem]

The present invention produces a slurry by mixing ittria-stabilized zirconia particles with a particle size of 1 to 5 μm, two or more groups of ittria-stabilized zirconia particles with a particle size of 1 μm or less and different diameters, and a binder. This is a method for producing an yttria-stabilized zirconia thin film that is in close contact with a substrate, which is characterized by coating the substrate and drying and baking it.

In the present invention, the particle size of the raw material ittria-stabilized zirconia particles is specified from the viewpoint of the filling state and sinterability of the raw material ittria-stabilized zirconia particles.

Even if the raw materials for ceramics, including yttoria-stabilized zirconia, have the same composition, the melting temperature varies depending on the size of the particles.Of course, the melting temperature will be higher for larger particles. The sintering temperature of ittria-stabilized ziconium particles of normal particle size is 1400-160.
0°C, and in the present invention, ittria-stabilized zirconia particles with a particle size of 1 to 5 μm (sintering temperature of 1400 to 1600°C) are selected based on that temperature, and these particles are used as the majority of the raw material ittria-stabilized zirconia 7. Use it to occupy. The remaining raw material is made of yttria-stabilized zirconia particles having a particle size of 1 μm or less. When raw material particles of both particle sizes are mixed and filled, the particle size is 1 μm.
The following small amount of particles fills the gaps between the large amount of particles having a particle size of 1 to 5 μm.

When sintered in this state, particles with a particle size of 1 μm or less will have a particle size of 1 μm or less.
Since it melts at a lower temperature than particles of ~5 μm and behaves like glue, it is no longer necessary to melt the entire raw material mixture particle to sinter it, and as a result, it becomes possible to sinter at a lower temperature than the conventional method.

For example, itria-stabilized zirconia particles with a particle size of 1 to 5 μm are usually sintered at 1400 to 1600°C;
When ultrafine ittria-stabilized zirconia particles of 01 to 102 μm are mixed, the sintering temperature is 1200 to 1200 μm.
It becomes 1300°C.

However, particles with a particle size of 1 to 5 μm and particles with a particle size of α01 to (
When a mixed raw material of ultrafine particles such as 102 μm is sintered,
Because there are no particles of intermediate particle size, the shrinkage due to sintering is large.
This causes the resulting ittria-stable diconia thin film to crack. Therefore, in the present invention, itria-stabilized zirconia particles with a particle size of 1 μm or less, medium to large particle sizes,
For example, at least two types of particles with different diameters, ie, particles with a diameter of 01 to 1 μm and particles with a smaller diameter, such as particles with a diameter of α01 to 1 μm, are used to prevent shrinkage during sintering. Of course, it is possible to mix three or more types of particles with a particle size of 1 μm or less, but this complicates the operation and is not a good idea.

Among ittria-stabilized zirconia particles with a particle size of 1 μm or less, particles with a relatively large particle size, such as αf' ~ 1 μm
m, preferably [particles with a diameter of L1 to α5 μm,
Particles with a relatively small particle size, such as CL01~(LO5,
Preferably, particles with a diameter of L101 to [1L02 μm are referred to as ultrafine particles, and when itria-stabilized zirconia particles with a particle size of 1 to 5 μm are mounted on coarse particles, the blending ratio of coarse particles: feed particles: super-imitation particles is ) IJ stabilization
The density of the Conia flake is determined by the particle size of each raw material particle so that it has the highest density. When blending ultrafine particles with a gL diameter of α01 to [102 μm, the ratio of coarse particles: fine particles: ultrafine particles =
tO:S: about 1 is preferable. Even if the ittria-stabilized zirconia particles are blended in this way, the slurry is formed, the coating is simply applied and dried, the density is 60 to 70%.

This value is significantly higher than that of a typical press-molded body of ittria-stabilized zirconia particles, which has a density of 50% or less.

The yttria-containing density of the yttria-stabilized zirconia used in the present invention is 1 to 20 mol% (2
If it exceeds 0 mol %, ittria will become unstable.) When itria is less than 8 mol %, partially stabilized zirconia is not obtained, and when it is more than 8 mol %, completely stabilized zirconia is obtained. Since itria is more expensive than zirconia, it should be used in the minimum necessary amount depending on the purpose, and when considering conductivity, about 8 mol % is optimal.

Ittria-stabilized di/I/:rnia raw materials are obtained by air classification using coarse particles with a particle size of 1 to 5 μm and fine particles with a particle size of α1 to (L5 μm), which are commercially available. It can be classified and used.

Further, itria-stabilized zirconia having ultrafine particles of α01 to 102 μm can be obtained by hydrothermally treating a mixed aqueous solution of zirconium oxychloride and yttrium chloride at a temperature of about 200°C.

A slurry of ittria-stabilized zirconia is produced by mixing ittria-stabilized zirconia of various particle sizes, adding a binder such as polyvinyl alcohol, and then adding water as a dispersion medium, followed by dispersion using a ball mill, followed by dispersion treatment. ,
Obtained by vacuum defoaming using a rotary evaporator.

〔Example〕

Commercially available 8 mol% ittria-stabilized zirconia with an average particle size of 1.5 μm was air classified into coarse particles of 1 to 5 μm (11
It was classified into fine particles of ~α5 μm.

Also, zirconium oxychloride (Zr0C4118/HI
O) 568 moA//t, yttrium chloride (YC7
4-6H, O) Add distilled water to give a concentration of 0.32-eμ/l, put the mixture in a Teflon-finished stainless steel pressure-resistant container, seal it, and after sealing, store it in a constant temperature bath at 200°C. The sample was placed in a container and maintained for 5 days (120 hours). In this way, itria-stabilized diμ-fair ultrafine particles having a particle size of about 15 OA (α015 μm) were obtained.

Next, regarding the above powder, the polymerization ratio is 10 to 5 μm coarse particles, 11 to 15 μm fine particles to 31 particles with a particle diameter of α05 μm.
m ultrafine particles were blended at a ratio of 1:1, polyvinyl alcohol was added as a binder to the powder at 1 wt%, water was added to this to make the slurry concentration 15 wtX, and then a ball mill was used. A slurry was obtained by grinding and mixing for 24 hours. Next, the slurry was vacuum degassed using a rotary evaporator to obtain a coating slurry.

This slurry has an average pore diameter of 1.511 m, a thickness of 1 cm,
The surface of an alumina base tube with a porosity of 65% was dip coated and then dried indoors. Next, the heating rate is 2°C/
The temperature was raised to 1250°C at a minimum speed of 1,250°C, maintained at this temperature for 4 hours, and then cooled with an oven.

By doing so, dense ittria-stabilized zirconium with a thickness of about 15 μm was formed on the surface of the alumina base tube.

For reference, after forming a slurry in the same manner as above using coarse particles of 1 to 5 μm, fine particles of 0.1 to O.S μm, and ultrafine particles of 15 μm, coating, drying, and baking were performed in the same manner. Sample A for comparison under the conditions of
/I prepared the money.

■Gas permeation method (N3
) and ■Conductivity (DC 4-terminal method) were used.

Evaluation using the gas permeation method is based on the differential pressure ('f4/,
, "> was given, and the gas permeability coefficient was determined from the amount of nitrogen that permeated through the pipe. The test results are shown in Figure 1. In Figure 1, the horizontal axis is the differential pressure (kg/J). The vertical axis is the gas permeability coefficient (Nm). In the figure, ■ is obtained by blending particles of five different particle sizes according to the present invention, and υ, ■, and ■ are those obtained by blending particles of 1 to 5 μm, and α1 to α1, respectively. It is 15 μm.

(The 1015 μm sample alone caused cracks and the transmittance was higher than that of the 1 to 5 μm sample.As a result of this test, the amount of gas permeation decreased by a small amount υ, indicating that the method of the present invention is useful. found.

The electrical conductivity was evaluated by attaching a lead wire for measurement using the 1-current 4-terminal method to the sample and then heating the sample. The measurement results of electrical conductivity are shown in FIG. In FIG. 2, the horizontal axis shows the reciprocal of the glycoside temperature multiplied by 111,000, and the vertical axis shows the conductivity. In the figure, ■ is obtained by blending three different particle sizes of the present invention, and ■■■ are those of 1 to 5 μm, 11 to 15 μm, and 1015 μm, respectively.

As a result of this test, the conductivity of the method of the present invention maintained a relatively high value, indicating that the present invention is useful. In ■■, sintering is insufficient, and in ■, cracks occur due to sintering, resulting in a decrease in electrical conductivity.

As described above, it has become clear that according to the present invention, it is possible to obtain a dense and highly uniform zirconia layer.

〔Effect of the invention〕

According to the present invention, it is possible to produce a dense ittria-stabilized zirconia thin film that adheres closely to a substrate at a relatively low temperature from the viewpoint of particle filling properties and the use of ultrafine particles.

[Brief explanation of the drawing]

Figure 1 is a chart showing the relationship between the differential pressure and gas permeability coefficient of the prototype sample, and Figure 2 is a chart showing the relationship between the temperature and electrical conductivity of the prototype sump μ.

Claims (1)

[Claims] A slurry is produced by mixing yttria-stabilized zirconia particles with a particle size of 1 to 5 μm, two or more groups of yttria-stabilized zirconia particles with a particle size of 1 μm or less and different diameters, and a binder, and the slurry is applied to a substrate. A method for producing an yttria-stabilized zirconia thin film that adheres to a substrate, the method comprising drying and baking the film.