JPH01223785A - Manufacture of composite piezoelectric material - Google Patents

Abstract

PURPOSE:To easily form a composite piezoelectric material having large anisotropy of piezoelectric characteristics by a method wherein a laminated body is made by winding a piezoelectric material and a composite material including bulking agent around a core which is dissipated when baked, and this body is baked. CONSTITUTION:A piezoelectric material is PZT(lead titanate zirconate), for example, and a material 11 as a green sheet having specified thickness is obtained by a slurry for molding. A composite material 15 including filler 13 is separately prepared. Then the material 11 obtained as a green sheet and the composite material 15 are laminated. Under appropriate temperature the material 11 and the composite material 15 are applied with pressure by a roll so that they can be conformed with each other, and a laminated body 17 is obtained. Then the laminated body 17 is wound around a core 19 of a hollow cylinder made of organic synthetic resin, for example, until specified thickness is reached to obtain a product 21. The product 21 is baked under temperature of approx. 600 to 700 deg.C. This eliminates filler 13 and realizes a composite piezoelectric material 25 consisting of PZT and air in voids 23 formed.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for manufacturing a composite piezoelectric material suitable for use in, for example, a transmitter or receiver of an underwater microphone, and in particular, relates to a method for manufacturing a composite piezoelectric material suitable for use in, for example, a transmitter or receiver of an underwater microphone. The present invention relates to a method of manufacturing a composite piezoelectric body including a substance having a dielectric constant different from that of the piezoelectric material.

(Prior art) Various piezoelectric materials have been used as materials for transducers and the like of acoustic sensors, but in order to improve sensor sensitivity, materials with large anisotropy in piezoelectric properties are desired. There is.

Methods for obtaining this large anisotropy include mixing piezoelectric ceramic powder into an organic material (e.g., epoxy resin, urethane resin, etc.), arranging piezoelectric ceramic rods at predetermined intervals,
There has been a method of filling the spaces between these piezoelectric ceramic rods with resin as described above.

In addition, as another method, for example,
As disclosed in Publication No. 10, slits are formed in advance in a green sheet of piezoelectric material, and the green sheets with slits are laminated and sintered, and the dielectric constant of the piezoelectric material is determined at the slit portion. There is a technique of filling materials with different dielectric constants, such as air or organic materials, to create a composite material.

(Problems to be Solved by the Invention) However, although the composite piezoelectric material obtained by combining the piezoelectric material and resin described above has a large hydrostatic constant, such as a volume sensitivity of 9 h, when used as an underwater micro-on, for example, The piezoelectric material has a problem in that its adhesion to the resin is weak and peeling often occurs.

In addition, in the case of the method disclosed in Japanese Patent Publication No. 59-14910, it is necessary to form slits in the green sheet in advance using mechanical technology, which increases the number of man-hours for manufacturing the bonded piezoelectric body and is difficult to handle. For this reason, there has been a problem in that it is difficult to achieve mass production and further reduce manufacturing costs.

The present invention has been made in view of the above points, and therefore, an object of the present invention is to easily manufacture a composite piezoelectric material with large anisotropy of piezoelectric properties so as to be able to construct a highly sensitive acoustic sensor. The goal is to provide a method that allows you to do so.

(Means for Solving the Problem) In order to achieve this object, according to the method for manufacturing a composite piezoelectric material of the present invention, a piezoelectric material and a substance having a dielectric constant different from that of the piezoelectric material are combined. In manufacturing a composite piezoelectric body, there are two steps: a step of impregnating a filler into a forming material made of piezoelectric material to create a composite forming material, and a step of adding the above-mentioned forming material and the above-mentioned composite forming material to a core that disappears by firing. A bond formed by laminating and rolling up a molded body,
The method is characterized in that it includes a step of firing the molded body 1j8.

Further, when carrying out the method of the present invention, it is preferable to use the above-mentioned filler as an organic substance or an inorganic substance.

(Function) According to the above-described structure of the present invention, a composite material in which a filler made of an organic or inorganic material is included in a material made of a piezoelectric material and the above-mentioned material are layered and wound around a core. to obtain a molded body. At this time, the core is made of a material that disappears at the firing temperature of the molded body.

Therefore, for example, when the filler is composed of an organic substance or other material that disappears at the firing temperature of the molded body, the portion of the composite piezoelectric body obtained by firing the molded body that corresponds to the layer made of the composite forming material A pore consisting of air is formed in the .

On the other hand, if an inorganic substance or other material that does not disappear at the firing temperature of the molded body is used as the above-mentioned filler, for example, the filler will remain in the part of the composite piezoelectric body made of the composite forming material. That's what happens.

(Embodiments) Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that the figures used in the explanation are merely illustrative to the extent that this invention can be understood, and therefore, the shapes, dimensions, arrangement relationships, and numerical examples of each component are not included in the embodiments described below. This is not intended to be limiting, and similar components in each figure are designated by the same reference numerals.

Various composite piezoelectric materials can be considered to which the method of the present invention can be applied; in this example, the piezoelectric material is PZT.
(lead zirconate titanate), and specific conditions will be explained by illustrating cases in which a substance having a dielectric constant different from that of PZT disappears at the firing temperature of the molded body, and cases in which it remains. . Further, although the configuration of the resulting composite piezoelectric body differs depending on the materials constituting these fillers, the same manufacturing process can be used. Therefore, in the following description, in order to avoid redundant explanation, the disappearance and remaining of the filler after firing will be expressed in a comprehensive manner.

As an example of a forming material of PZT as a piezoelectric material, P
The manufacturing process using a green sheet made of ZT will be explained.

First, each chemically highly pure Pb0(-oxidized!
8) Weigh predetermined amounts of TiO2 (titanium dioxide) and Zr02 (zirconium dioxide), respectively, in accordance with the composition ratio of Pb(2r-Ti)03. Thereafter, these mixed powders are mixed with pure water for about 20 hours using a pot mill according to a conventionally known ceramic process.

Subsequently, the above-mentioned mixture is dehydrated and dried to give about 900 to 10
By calcining at a temperature of 00℃ for about 2 hours,
Obtain a calcined product. Thereafter, using the Bot mill again, pure water is added to the above-mentioned calcined product, which is pulverized and dehydrated and dried to obtain a PZT calcined product.

Next, to the above calcined powder 100 (9), pure water 20 (
9) and peptizer (manufactured by Wara-Kogyo Yakuhin ■, rCeramo D-+3
4Jl (Add product 8-2.5 (9). After that,
The mixtures are mixed using a pot mill for about 4-5 hours.

Next, a binder (manufactured by Daiichi Kogyo Yakuhin ■, Ii'Ceramo T8-13.71 (trade name)) was added to the above mixture.
40(9), plasticizer (manufactured by Daiichi Kogyo Yakuhin ■, Ii' Ceramo P-17, U (trade name)) 5 (9), antifoaming agent (manufactured by Daiichi Kogyo Yakuhin ■, ii' Acitiflos Fa02.o (Product name))0.2(9)! In addition, rough mixing is carried out in a ball mill for about 20 hours to obtain a forming material slurry consisting of PZT.

In addition, apart from this, the above-mentioned PZT calcined powder 100 (
9), pure water 30 (9), and the above-mentioned deflocculant 4 (9)
), the above-mentioned binder 60 (C1), the above-mentioned plasticizer 10
(9), polyethylene particles (particle size 100-5
00(um) ) 30 (9) fir, using
A slurry for a composite forming material made of PZT was prepared through a similar process. Incidentally, as described above, in this step, even if other materials are used as the filler, the same procedure can be carried out.

Hereinafter, embodiments of the manufacturing method of the present invention will be described in detail with reference to the drawings.

FIGS. 1(A) to 1(E) are schematic explanatory diagrams (shown in perspective) for each step in order to explain the present invention in detail.

Further, in these figures, in order to facilitate understanding of the explanation, some of the constituent components are shown cut away, and hatching indicating the cross section is omitted.

First, using the slurry for forming material obtained through the above-mentioned procedure, using a well-known doctor blade device, for example, 0,
A forming material 11 as a green sheet having a predetermined thickness of about 2 to 0.3 (mm) is obtained (FIG. 1(A)).

Separately from this, a composite forming material 15 containing a filler 13 is obtained in the same manner using a slurry for a composite forming material (FIG. 1(B)).

Next, the forming material 11 obtained as a green sheet and the composite forming material 15 are overlapped. Thereafter, the forming material 11 and the composite forming material 15 are pressurized with rolls at an arbitrary suitable temperature so that they suitably blend together to form a laminate 17, resulting in the state shown in FIG. 1(C).

Next, for example, it is made of organic synthetic resin and has a cylindrical (hollow) shape.
A core body 19 is prepared, and the above-described laminate 17 is wound around the core body 19 until it has a predetermined thickness according to the design, and a molded body 21 in the state shown in FIG. 1(D) is formed. obtain.

The above-mentioned core body 19 may have a cross-sectional shape other than a circle, but may be a columnar or cylindrical quadrangle, or any other shape depending on the design. Furthermore, the material of the core body 19 is not limited to the above-mentioned organic synthetic resin, but may also be a material that disappears in some form during the firing process, wax, or any other suitable material. It is also suitable to use

The layers (portions corresponding to the forming material 11 or the composite forming material 15) constituting the cylindrical molded body 21 wound up in this manner are arranged alternately in the radial direction of the core body 19. It is in a state.

Of the above-mentioned steps, for example, in the production of the laminate 17 explained with reference to FIG. 1(C) and the production of the molded body 21 explained with reference to FIG. 1(D), as a product The above-described forming material 11 and composite forming material 15 of the composite piezoelectric body
There may be cases where it is necessary to consider peeling, cracks, etc. that occur in the corresponding part between the two. In such a case, for example, when producing the laminate 17, as described above, the case where pressure is applied using a roller has been described as an example, but the above-mentioned binder etc. It is also suitable to perform this by coating. In addition, when producing the molded body 21, in addition to applying the binder described above, the laminate 1
7 may be wound up while applying tension, or may be pressurized using a mold having a predetermined suitable shape.

Next, the length of the above-mentioned molded body 21 is adjusted by cutting it with a suitable method such as a cutter so that it has a length determined by, for example, the operating frequency of the transmitter/receiver.

Subsequently, the above-described molded body 21 is fired at a temperature in the range of approximately 600 to 700° C. for several hours.

In this question, the binder etc. added when preparing the green sheet,
The core 19 or the polyethylene particles as the filler 13 in this embodiment disappear. In this example, since the filler 13 uses a material that disappears by firing,
As shown in FIG. 1(E), holes 23 are formed.
A composite piezoelectric material 25 of PZT and air is obtained.

In this case, in the composite piezoelectric body 25, the anisotropy 'i of the ratio of PZT to pores can be adjusted by controlling the amount of the filler 13 added when preparing the slurry for the composite forming material. When configuring the laminate 17, the anisotropy of the composite piezoelectric body can also be easily controlled by adjusting the relative thicknesses of the forming material 11 and the composite forming material 15.

In the above-described embodiments, the green sheet is formed by the doctor blade method, but it may be formed by any other suitable technique.

Although the embodiments of the present invention have been described above, the method of the present invention is not limited to the above embodiments.

For example, in the above-described embodiment, the piezoelectric material tPZT was used, but it is clear that the manufacturing method of the present invention can be applied even if the piezoelectric material is changed to another suitable material.

In addition, although the case where granular polyethylene is used as the hollow filler has been described, other fillers that are made of materials other than polyethylene and that substantially disappear during firing may be used, and the shape may also be granular. It is not limited.

Furthermore, as already explained, the effects of the present invention are not limited to fillers that disappear during firing. The present invention can also be applied to fillers made of inorganic materials such as silicon carbide, zirconia, alumina, etc. and having any suitable shape as such materials, and a composite piezoelectric body with excellent strength can be easily and easily produced. obtain.

It is clear that these materials, shapes, dimensions, dimensional relationships, numerical conditions, and other conditions can be arbitrarily and appropriately changed and modified according to the design without departing from the scope of the present invention.

(Effects of the Invention) As is clear from the above explanation, according to the method for manufacturing a composite piezoelectric material of the present invention, a composite forming material in which a filler made of an organic or inorganic material is included in a forming material made of a piezoelectric material. , the above-mentioned forming material is wound around a core body in a laminated state,
Obtain a molded body.

Therefore, by appropriately selecting a material that disappears at the firing temperature of the compact or a material that remains at the firing temperature as the core material depending on the design, a composite piezoelectric body suitable for the purpose can be easily and easily obtained. be able to.

Furthermore, by variously changing the size or shape of the filler, the density of the filler, the direction, etc., it is possible to easily adjust the anisotropy of the piezoelectric properties.

Therefore, it is possible to easily manufacture a composite piezoelectric material having a large anisotropy of piezoelectric properties, which can constitute a highly sensitive acoustic sensor.

[Brief explanation of the drawing]

FIGS. 1(A) to 1(E) are schematic process diagrams showing a method for manufacturing a composite piezoelectric body of the present invention. 11...forming material, 13...filling material, 15...
- Composite forming material 17... Laminated body, 19... Core body,
21... Molded body 23... Holes, 25... Composite piezoelectric body. Patent applicant: Oki Electric Industry Co., Ltd.Explanatory diagram of the embodiment (Figure 1 GC) Figure 1 (GC)

Claims (1)

[Claims] (1) When manufacturing a composite piezoelectric body of a piezoelectric material and a substance having a dielectric constant different from that of the piezoelectric material, a filler is included in a forming material made of a piezoelectric material to produce a composite forming material. and a step of laminating the forming material and the composite forming material on a core that disappears by firing and winding them to form a molded body, and then firing the molded body. Method for manufacturing composite piezoelectric material.