JPH05163054A - Complex electrostrictive ceramics, its production and displacement element using the same ceramics - Google Patents

Abstract

PURPOSE:To provide electrostrictive ceramics manufactured at low temperature and a displaced element comprising the ceramics. CONSTITUTION:Calcined powder having a composition ratio of 0.5Pb(Ni1/3Nb2/3) O3-0.4PbTiO3-0.1Ba(Zn1/3Nb2/3)O3, ground into 3.2mum average particle diameter is mixed with PbO B2O3-based on glass powder having 3.8mum average particle diameter and ground into about 0.2mum average particle diameter by a medium stirring mill to give electrostrictive ceramics powder, which is press molded and burnt to produce complex electrostrictive ceramics 1 wherein the electrostrictive ceramics powder 2 is randomly dispersed into a matrix of glass 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite electrostrictive ceramic, a method for producing the same and a displacement element using the same, and more particularly, a method for producing a composite electrostrictive ceramic which can be produced and fired at a low temperature and a method for producing the same. It relates to a displacement element. The present invention also relates to a composite electrostrictive ceramic useful for positioning precision machinery, displacement elements such as video auto-tracking actuators, and a method for producing the same.

[0002]

2. Description of the Related Art A displacement element using an electrostrictive material does not need polarization treatment, has no or little history of displacement, and has no or little change due to aging, as compared with a displacement element using a piezoelectric material. It is also used as various actuators because it has excellent heat resistance and heat resistance.

As electrostrictive ceramics, Pb has hitherto been used.
(Mg _1/3 Nb _2/3 ) _x Ti _y O ₃ binary system (however, X +
Y = 1), Pb (Ni _1/3 Nb _2/3 ) O ₃ -PbTiO
There is a ceramic material composed of _3- Ba (Zn _1/3 Nb _2/3 ) O ₃ ternary composition (Japanese Patent Publication No. 61-31926). Almost all of the constituents of these conventional ceramic materials are ceramics, and they are produced by forming a raw material or a calcined powder into a predetermined shape and then firing it at a high temperature. Further, as a material which can be produced at a relatively low temperature, there is a mixture of the ceramic powder and an organic substance such as rubber or epoxy resin.

[0004]

Conventional electrostrictive ceramics generally have a high firing temperature and must be fired at a high temperature of 1100 to 1300 ° C. Therefore, the internal electrodes that constitute the element are exposed to the high firing temperature as described above, and therefore it is necessary to use expensive platinum or the like that is not easily oxidized or deteriorated even at high temperatures. Become. Therefore, there is a problem that the cost becomes high as an element such as various parts and it is difficult to use for general purpose.

Further, if the electrostrictive ceramics can be made into a thin film, the displacement element can be made thinner when applied to, for example, a displacement element, so that it can be operated at a low voltage and can be miniaturized. Although there are great advantages, the conventional materials are limited to platinum, which is difficult to form into a thin film and which is expensive as a substrate material, and ceramics having excellent heat resistance. Further, the electrostrictive material made of a mixture with an organic material has a problem that it is inferior in heat resistance, has a small elastic constant, and cannot cope with a large stress.

In order to solve the above conventional problems, it is an object of the present invention to provide an electrostrictive ceramic which can be fired or processed at a low temperature and has excellent heat resistance, a method for producing the same, and a displacement element using the same. And

[0007]

In order to achieve the above object,
The composite electrostrictive ceramics of the present invention comprises at least a composite of electrostrictive ceramic powder and glass.

Further, in the above constitution, it is preferable that the electrostrictive ceramic powder has an average particle diameter of 2 μm or less. The present invention also provides composite electrostrictive ceramics comprising at least electrostrictive ceramic powder and a composite of glass and whiskers.

In the above structure, it is preferable that the electrostrictive ceramic powder has an average particle diameter of 2 μm or less and the whiskers have an average length of 50 μm or less. Also,
In the composite electrostrictive ceramics of the present invention, the glass is preferably crystallized glass.

Further, the method for producing the composite electrostrictive ceramics of the present invention is characterized in that at least the electrostrictive ceramic powder and the glass are mixed and pulverized to have an average particle diameter of 0.6 μm or less, followed by molding and firing.

Further, the displacement element of the present invention is a displacement element in which electrode layers are formed on the front surface and the back surface of a composite electrostrictive ceramic layer made of a composite of at least electrostrictive ceramic powder and glass.

As the electrostrictive ceramic powder used in the present invention,
Is any powder of electrostrictive ceramics
Well, specifically, for example, Pb (Mg_1/3Nb_2/3)_xT
i_yO₃Binary system (however X + Y = 1), Pb (Ni_1/3
Nb_2/3) O₃-PbTiO ₃-Ba (Zn_1/3Nb
_2/3) O₃Ceramic materials consisting of three-component composition, etc.
Which is the representative one. Electrostrictive ceramics
The powder used preferably has an average particle size of 2 μm or less.
Since it is easy to obtain a high-density molded product,
preferable. For example, a ball mill with a large average particle size
Needless to say, it may be crushed for use. Electrostriction
The lower limit of the average particle size of ceramic powder is the average showing electrostriction.
Any particle size will do. This is the electrostrictive ceramic
Since there is an inherent lower limit that differs depending on the type and composition, that
It depends on each one. For example, in the composition of Example 1 below
Is a composite electrode of the present invention even if the average particle size is about 0.010 μm.
Strained ceramics show electrostrictive characteristics. In addition, the eye of the present invention
Various other ceramic materials, such as
For example, various types of ceramics such as alumina, zirconia, titania, etc.
You may use mix etc. suitably. However, these are
If used in a large amount, electrostrictive properties will decrease and sinterability will decrease.
Therefore, as long as these properties do not deteriorate so much
It is desirable to use.

The glass used in the present invention is not particularly limited.
However, various types of glass can be used.
As an example, for example, PbO · B₂O₃Glass, Pb
OB₂O₃・ SiO₂Glass, PbO / ZnO / B
₂O₃Glass, ZnO / B ₂O₃・ SiO₂System glass
Various glasses can be used. Especially these
The use of crystallized glass obtained by crystallizing
Preferred for improving heat resistance of composite electrostrictive ceramics
Yes. As a glass, it is chemically stable and has a coefficient of thermal expansion.
Should be close to the coefficient of thermal expansion of electrostrictive ceramics.
Good.

The mixing ratio of the electrostrictive ceramic powder and the glass is usually 10 to 90 vol% of the electrostrictive ceramic powder.
On the other hand, it is preferably used in the range of 90 to 10 vol% of glass.

When the electrostrictive ceramic powder and glass are mixed and pulverized, it is preferable to use a medium stirring mill because fine pulverization can be performed in an extremely short time. By reducing the particle size of the electrostrictive ceramic powder or the glass powder, the thickness of the composite electrostrictive ceramic can be made as thin as possible, which is preferable.

When using whiskers together, for example,
Magnesia whiskers, zirconia whiskers, SiC
The whiskers, ZnO whiskers, potassium titanate whiskers, Si ₃ N ₄ whiskers, zirconia whiskers and the like are not particularly limited as long as the objects of the present invention can be achieved, and other appropriate whiskers can be used.

The whiskers referred to in the present invention include fibrous glass such as glass fibers such as quartz glass fibers having good heat resistance, and ceramics such as barium titanate and strontium titanate. If the length of the whiskers exceeds 50 μm, the density of the composite electrostrictive ceramics may be reduced, and the electrostrictive property may be deteriorated. Therefore, it is preferable to use whiskers having a length of 50 μm or less. Further, it is preferable that the length of the whiskers is made smaller when the average particle diameter of the ferroelectric ceramic powder is small. Usually, it is preferable that the length of the whiskers is 2 μm or more in order to exert the bending strength improving effect.

It is preferable to use whiskers in an amount of usually 15 vol% or less in order not to cause a sharp decrease in electrostriction. For molding, various molding methods that can be used for molding ceramic powder can be adopted, and appropriate methods such as pressure molding, casting molding, extrusion molding, doctor blade method, dipping method, and printing method can be applied.

The firing temperature may be near the glass sintering temperature,
Therefore, firing at a low temperature becomes possible. The specific firing temperature varies depending on the type of material used and cannot be specified unconditionally, but is usually in the range of about 300 ° C to 800 ° C. However, it is not limited to this.

The composite electrostrictive ceramics of the present invention are
For example, it can be formed on various ceramic substrates, metal substrates, electrodes, or the like. In the composite electrostrictive ceramics of the present invention, the electrostriction can be controlled in a wider range than before by changing the mixing ratio of the electrostrictive ceramic powder and the glass.

Further, it is desirable that the composite electrostrictive ceramics of the present invention have as few pores as possible in order to obtain an element having high mechanical strength and an element having excellent moisture resistance. However, inclusion of pores does not hinder the effect of the present invention.

FIG. 1 is a conceptual diagram showing an example of a cross-sectional structure of a composite electrostrictive ceramic 1 comprising electrostrictive ceramic powder 2 and glass 3 according to the present invention. Glass 3 serves as a matrix and electrostrictive ceramic powder 2 serves as glass 3. In the matrix, the particles are randomly dispersed and dispersed, and three-dimensionally, the glass region itself forms a three-dimensional continuous layer.

FIG. 2 is a sectional view showing an example of the structure of the displacement element 4 using the composite electrostrictive ceramics of the present invention. Reference numeral 1 is a composite electrostrictive ceramics layer of the present invention, which is formed on both sides of a metal plate 7 which serves as a substrate and also serves as an electrode. The composite electrostrictive ceramics layer 1 is usually formed by coating the metal plate 7 with a slurry of electrostrictive ceramics powder and glass powder by coating or dipping, and then drying and firing. be able to. After firing, any of the composite electrostrictive ceramic layers formed on both sides of the metal plate 7 is left by leaving a part of its peripheral portion by Cr-Au or other electrodes 5 and 6 by evaporation or the like (here, the electrode 5 is the a electrode, the electrode 6 as the b electrode.) Is formed. However, in addition to the metal plate 7, a
Although the displacement element is provided with the electrode and the b electrode, it may be provided with only one of the a electrode and the b electrode. Also,
In this example, the fixed end 9 of the portion of the metal plate 7 where the composite electrostrictive ceramics is not formed is fixed with an adhesive or the like.
The displacement element is configured by being fixed to. In the former case, the open end 10 is moved to the left by applying a DC electric field between the metal plate 7 and the a electrode 5 or the metal plate 7 and the b electrode 6 which are the central electrodes of this displacement element. It can be displaced, and in the latter case the release end 10 can be displaced to the right.

[0024]

Since the composite electrostrictive ceramics of the present invention comprises at least a composite of electrostrictive ceramic powder and glass,
It is possible to provide the electrostrictive ceramics which can be manufactured at a remarkably low temperature as compared with the conventional material consisting only of the electrostrictive ceramics.

Further, preferably, by setting the average particle diameter of the electrostrictive ceramic powder to 2 μm or less, it is possible to provide a high density electrostrictive ceramic which can be manufactured at a low temperature.

Further, the composite electrostrictive ceramics of the present invention is
By configuring at least the electrostrictive ceramic powder and the composite of glass and whiskers, it is possible to provide the electrostrictive ceramic with high mechanical strength that can be manufactured at low temperature.

In the above composite electrostrictive ceramics,
By setting the average particle size of the electrostrictive ceramic powder to 2 μm or less and the average length of the whiskers to 50 μm or less, it is possible to provide a high-density electrostrictive ceramic with high mechanical strength that can be manufactured at low temperature. ..

Further, in the composite electrostrictive ceramics of the present invention, by using glass as crystallized glass, it is possible to provide the composite electrostrictive ceramics excellent in heat resistance which can be manufactured at a low temperature.

Further, in the method for producing the composite electrostrictive ceramics of the present invention, at least the electrostrictive ceramic powder and the glass are mixed and pulverized to have an average particle size of 0.6 μm or less, which is then molded and fired. Ceramics can be manufactured at low temperatures.

Further, in the displacement element of the present invention, since the electrode layers are formed on the front surface and the back surface of the composite electrostrictive ceramic layer composed of at least a composite of electrostrictive ceramic powder and glass, the composite electrostrictive electrode is formed on the electrode at a low temperature. It is possible to form ceramics, and it is possible to provide a displacement element using a cheaper material as an electrode material.

[0031]

EXAMPLES Hereinafter, examples will be described to facilitate understanding of the present invention, but the present invention is not limited to these examples.

Example 1 As an electrostrictive ceramic powder, 0.5 Pb (Ni _1/3 Nb) was used.
_2/3 ) O ₃ -0.4 PbTiO ₃ -0.1 Ba (Zn _1/3 N
b _2/3 ) O ₃ composition ratio calcined powder (120 after mixing the raw materials
It was calcined at 0 ° C for 2 hours and then pulverized with a ball mill to an average particle size of 3.2 µm) and glass powder (Nippon Electric Glass Co., Ltd. PbO / B ₂ O ₃ based glass powder, product number CF).
-8, average particle diameter 3.8 μm, and this glass contains some ceramic powder) were weighed at the ratio shown in (Table 1), and then a medium stirring mill (Eiger Engineering Co., Ltd.) using ethanol as a dispersion medium. "Motor mill M5
0 "," Pulverizing medium: zirconia boulder with a diameter of 0.4 mm,
At a peripheral speed of a stirrer of 10 m / s), an average particle diameter of about 0.2 μm was mixed, pulverized, and dried. Then, the particles were granulated with pure water, and then passed through a 500 μm sieve for sizing. This powder is pressure-molded using a mold to produce a plate-shaped molded body having a length of 10 mm, a width of 5 mm and a thickness of about 1 mm, which is fired for 2 hours in an electric furnace to obtain a composite electrostrictive ceramic. It was made. The rate of temperature rise / fall is 400 ° C./h. Cr on both sides of the plate sample after firing
An electrostrictive element was obtained by applying a vapor deposition electrode of -Au. A DC electric field of 2 kV / mm was applied between both electrodes of this sample, and the displacement amount in the length direction of the sample was measured using a differential transformer type displacement meter.
The amount of displacement is shown by the rate of change. The measurement results are shown in Table 1.

[0033]

[Table 1]

As is clear from Table 1, the composite electrostrictive ceramics of the present invention were manufactured according to Comparative Example No. Although the amount of displacement is slightly lower than that of the electrostrictive ceramic of No. 8, it can be manufactured at a remarkably low temperature. In addition, No. In Comparative Example No. 8, when the firing temperature is 1000 ° C. or less, no sintering occurs. In addition,
No. The average particle size after mixing and pulverizing with a medium stirring mill at the same compounding ratio as 5 is 2.4, 1.12, 0.56, 0.1.
At 9 and 0.063 μm, the density of the sintered body was 93, 94, 98, 99 and 98% of the theoretical density, respectively. When the average particle size after mixing and pulverizing was 0.6 μm or less, the density became high. It can be fired, but if it exceeds 0.6 μm, the firing density is small and it is difficult to obtain dense ceramics.

Further, in the above embodiment, the electrostrictive ceramic powder and the glass were mixed and pulverized by the medium stirring mill, but they may be pulverized separately and then mixed. In this case, the average particle size of the electrostrictive ceramic powder is preferably 2 μm or less. If it exceeds 2 μm, the sinterability is significantly reduced. That is, when the average particle diameters of the electrostrictive ceramic powder are 3.2, 1.9, and 0.51 μm, the densities of the sintered bodies are 70, 89, and 93% of the theoretical density, respectively. If the average particle diameter of the ceramic powder exceeds 2 μm, the sintered density is small. Mixing and pulverizing with a medium stirring mill is preferable because the degree of mixing of the electrostrictive ceramic powder and glass is improved, the homogeneity of the composite electrostrictive ceramic is improved, and the sinterability is also improved.

Example 2 As an electrostrictive ceramic powder, 0.5 Pb (Ni _1/3 Nb) was used.
_2/3 ) O ₃ -0.4 PbTiO ₃ -0.1 Ba (Zn _1/3 N
b _2/3 ) O ₃ composition ratio calcined powder (120 after mixing the raw materials
After calcination at 0 ° C. for 2 hours, powder pulverized with a ball mill to an average particle size of 3.2 μm) and glass powder (PbO / B ₂ O ₃ system glass powder manufactured by Nippon Electric Glass Co., Ltd., product number CF-
8. Average particle diameter of 3.8 μm, and this glass contains some ceramic powder) were weighed at the ratio shown in Table 2, and then a medium stirring mill (Eiger Engineering's “motor mill” was used as a dispersion medium). M50 ″, grinding medium: zirconia boulders with a diameter of 0.4 mm, and an agitator peripheral speed of 10 m / s) were mixed and ground to an average particle diameter of about 0.2 μm, and then dried. This mixed pulverized powder and magnesia whiskers (magnesia having an average diameter of about 2 μm and an average length of 24 μm)
And were mixed in the ratio shown in Table 2, granulated with pure water, and passed through a 500 μm sieve for sizing. This powder is pressure-molded using a mold to produce a plate-shaped molded body having a length of 10 mm, a width of 5 mm and a thickness of about 1 mm, which is fired for 2 hours in an electric furnace to obtain a composite electrostrictive ceramic. It was made. The rate of temperature rise / fall is 400 ° C./h. After firing, Cr-
A vapor deposition electrode of Au was applied to obtain an electrostrictive element. A DC electric field of 2 kV / mm was applied between both electrodes of this sample, and the displacement amount in the length direction of the sample was measured using a differential transformer type displacement meter. Table 2 shows the measurement results of the displacement amount and the bending strength.

[0037]

[Table 2]

As shown in Table 2, the composite electrostrictive ceramics containing whiskers can have a higher flexural strength than those without whiskers. As described above, as the whiskers, other appropriate whiskers other than the above can be used as long as the objects of the present invention such as zirconia and SiC whiskers other than those in the examples can be achieved.

Example 3 Nos. Of Examples 1 and 2 were used. Regarding 3 and 10, as the glass material, crystallized glass (PbO · manufactured by Nippon Electric Glass Co., Ltd.)
ZnO / B ₂ O ₃ type powder glass, product number “LS-710
A composite electrostrictive ceramics was produced by substantially the same method as in the above-mentioned example except that 5 ″ and an average particle diameter of 7.5 μm) were used.
The amount of displacement and the deformation temperature of these samples were measured. The measurement results are shown in Table 3. The deformation temperature was a temperature at which the corners of the disk-shaped sample were rounded when each temperature was maintained for 5 hours.

[0040]

[Table 3]

As shown in Table 3, when the crystallized glass was used as the glass, the deformation temperature was significantly higher than that of the non-crystallized glass, and the heat resistance of the composite electrostrictive ceramic was remarkably improved. Therefore, the composite electrostrictive ceramics using crystallized glass is preferable because it can withstand high temperature processing and heat treatment.

Example 4 As an electrostrictive ceramic powder, 0.5 Pb (Ni _1/3 Nb) was used.
_2/3 ) O ₃ -0.4 PbTiO ₃ -0.1 Ba (Zn _1/3 N
b _2/3 ) O ₃ composition ratio calcined powder (120 after mixing the raw materials
After calcination at 0 ° C. for 2 hours, powder pulverized with a ball mill to an average particle size of 3.2 μm) and glass powder (PbO / B ₂ O ₃ system glass powder manufactured by Nippon Electric Glass Co., Ltd., product number CF-
No. 8 in Table 1, No. 8, average particle diameter 3.8 μm, and this glass contains some ceramic powder). After weighing at the ratio shown in 4, the medium stirring mill (“Motor Mill M” manufactured by Eiger Engineering Co., Ltd., using ethanol as a dispersion medium).
50 ", grinding medium: zirconia cobblestone with a diameter of 0.4 mm,
The peripheral speed of the stirrer was 10 m / s), and the mixture was pulverized to an average particle diameter of about 0.2 μm. This mixed and crushed slurry has a length of 20 m
Dip coating was performed on both surfaces of a stainless steel plate having m, a width of 5 mm, and a thickness of about 0.05 mm, leaving 5 mm in the length direction. After drying, this was baked at 450 ° C. for 2 hours to obtain a composite electrostrictive ceramic film having an average thickness of 0.045 mm. Using this, an electrostrictive element as shown in FIG. 2 was created. After firing, Cr-Au vapor deposition electrodes (a electrode 5 and b electrode 6) were formed leaving 1 mm on both sides of the composite electrostrictive ceramics layer 1 to obtain an electrostrictive element. As shown in FIG. 2, the displacement element 4 was constructed by fixing the fixed end 9 of the metal plate 7 made of a stainless steel plate without the composite electrostrictive ceramics layer 1 to the fixed block 8 with an epoxy resin adhesive. A direct current electric field of 2 kV / mm was applied between the metal plate 7 and the a electrode 5 or the metal plate 7 and the b electrode 6 to be the central electrode of this sample, and using an optical microscope,
The flexural displacement of the open end 10 of the sample was measured. In the former,
The open end 10 was displaced 122 μm to the left. In the latter case, the displacement was 105 μm to the right.

As described above, the composite electrostrictive ceramics of the present invention can be manufactured at a significantly lower temperature than conventional electrostrictive ceramics. For this reason, a large-area thin film electrostrictive ceramic can be produced on a variety of substrates such as metal plates made of stainless steel by a coating method or the like. Further, the present invention is easy to form a thin film, and by making the electrostrictive ceramic powder and the glass powder fine, it is possible to reduce the thickness of the composite electrostrictive ceramic and the displacement element formed thereof to the order of nanometer.

[0044]

INDUSTRIAL APPLICABILITY The composite electrostrictive ceramics of the present invention can provide electrostrictive ceramics which can be manufactured at a remarkably low temperature as compared with the conventional materials consisting of only electrostrictive ceramics. Therefore, even when used in combination with a material having low heat resistance, which could not be used until now, it can be effectively used for manufacturing various elements.

Further, by setting the average particle diameter of the electrostrictive ceramic powder to 2 μm or less, it is possible to provide an electrostrictive ceramic which can be manufactured at a higher density and at a lower temperature. Further, by using whiskers together with the composite electrostrictive ceramics of the present invention, it is possible to provide electrostrictive ceramics having higher mechanical strength and which can be manufactured at a low temperature.

In the composite electrostrictive ceramics of the present invention, the electrostrictive ceramic powder has an average particle diameter of 2 μm or less, and the whiskers have an average length of 50 μm or less, so that it can be manufactured at a low temperature. It is possible to provide high-density electrostrictive ceramics having high mechanical strength.

Further, in the composite electrostrictive ceramics of the present invention, by using glass as crystallized glass, it is possible to provide a composite electrostrictive ceramics which can be manufactured at a low temperature and which is more excellent in heat resistance.

The method for producing the composite electrostrictive ceramics of the present invention can provide a method for producing high density electrostrictive ceramics at a low temperature. Further, the displacement element of the present invention can provide a displacement element using a material having low heat resistance or an inexpensive material as an electrode material or other material.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing an example of a sectional structure of a composite electrostrictive ceramics of the present invention.

FIG. 2 is a schematic sectional view showing an example of a structure of a displacement element using the composite electrostrictive ceramics of the present invention.

[Explanation of symbols]

 1 Composite Electrostrictive Ceramics 2 Electrostrictive Ceramics Powder 3 Glass 4 Displacement Element 5 a Electrode 6 b Electrode 7 Metal Plate 8 Fixed Block 9 Fixed End 10 Open End

Claims (7)

[Claims] 1. A composite electrostrictive ceramic comprising a composite of at least electrostrictive ceramic powder and glass. 2. The average particle diameter of the electrostrictive ceramic powder is 2
The composite electrostrictive ceramic according to claim 1, wherein the composite electrostrictive ceramic has a thickness of not more than μm. 3. A composite electrostrictive ceramic comprising at least an electrostrictive ceramic powder and a composite of glass and whiskers. 4. The average particle diameter of the electrostrictive ceramic powder is 2
is less than μm, and the average length of the whiskers is 50μ
The composite electrostrictive ceramic according to claim 3, wherein the composite electrostrictive ceramics has a thickness of m or less. 5. The glass according to claim 1, which is a crystallized glass.
4. The composite electrostrictive ceramic according to any one of 4 above. 6. At least electrostrictive ceramic powder and glass are mixed and pulverized to have an average particle size of 0.6 μm or less,
A method for producing a composite electrostrictive ceramic, which comprises molding and firing. 7. A displacement element in which electrode layers are formed on the front surface and the back surface of a composite electrostrictive ceramic layer made of a composite of at least electrostrictive ceramic powder and glass.