JPS608990B2 - Method for manufacturing piezoelectric sintered sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a piezoelectric sintered sheet made of a lead-based piezoelectric material, and particularly relates to a piezoelectric sintered sheet having an average particle diameter of 1.0 m.
Using the following lead-based piezoelectric material, the thickness is 0.5 to 2. The purpose of the present invention is to provide a method that can easily and stably produce a smooth, high-density piezoelectric compact sheet that does not cause cracks or deformation even when the green sheet of the "Kou Misaki" sheet is compacted. .

Recently, piezoelectric ceramics have been applied to a wide variety of fields, and their density and size have rapidly increased. Conventionally, piezoelectric elements have been obtained by cutting, polishing, etc. a composite block depending on the application. Particularly in the field of application where thin plates of Shoden ceramic are used, there are many factors that are disadvantageous to mass production, such as the distortion caused by these processes deteriorating the electrical characteristics of the element and the processing costs being high. As a method to solve these problems, a piezoelectric ceramic material is kneaded with a binding substance to create a slurry, poured onto a smooth substrate such as an organic film, formed into a sheet of a certain thickness using a doctor blade method, and dried. A method is known in which a smooth raw sheet is produced, punched into a desired shape depending on the intended use, and then fired. However, shrinkage during firing causes deformation, cracks, warpage, pores, and even non-uniform composition in the bran sheet after firing, which poses the problem of having a significant impact on mechanical and electrical properties. . In order to obtain high-performance, high-precision sintered sheets, it is necessary to increase the density of the raw sheet as much as possible. To achieve this, it is necessary to control the raw material particle size and add a small amount of binder and plasticizer to the ceramic material. In addition, it is important to thoroughly knead the material with an appropriate amount of solvent to ensure good dispersion of the ceramic material, and to ensure that punching is easy and that no processing distortion remains. In addition, for piezoelectric materials containing lead, it is necessary to carefully consider the temperature, atmosphere, filling method, etc. in the firing process.

For this reason, up until now, a high-temperature oxide was uniformly applied to the raw sheet and laminated in several layers, thereby lowering the specific surface area of the raw sheet and suppressing the evaporation of lead. It is placed in an electric furnace, pre-fired to remove organic components, and then main fired at a predetermined temperature.
A method has been used to obtain a lead-based piezoelectric composite sheet with high density, high homogeneity, and excellent smoothness. However, in this case, the powder particle diameter of the lead-based piezoelectric material is 1 to 3A.
m, the amount of binder and plasticizer added to the ceramic body is small. In addition, since the thickness of the green sheet to be formed was approximately 100 m, the forming, preliminary firing, and main firing of the sheet were easy. However, when trying to use a lead-based piezoelectric material with an average particle diameter of 1.0 mm or less, the dispersibility of the powder particles is poor and cracks tend to occur in the raw sheet.

In addition to that, raw sheets can be added to 0.5 to 2. The thicker the material, the more difficult it becomes to produce a green sheet. For this reason, it was necessary to add binders and plasticizers in larger amounts than in the past. If a large amount of binder or plasticizer was added, the sintered sheet would deform, crack, or warp, making it impossible to manufacture it under the same pre-firing conditions and main firing conditions as the secondary one. The present invention eliminates these defects and makes it possible to easily and stably produce a smooth, high-density piezoelectric heating element sheet.

The lead-based piezoelectric ceramic material used in the method of the present invention may be a single-component type, a two-component type, or a ternary-component type consisting of a berovskite type compound or a tungsten freon type compound.

Examples of the organic binder include polyvinyl butyral, polyvinyl alcohol, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, methyl cellulose, ethyl cellulose, and the like. As the plasticizer, phthalate-based dibutyl phthalate, dioctyl phthalate, dioctyl adipate, glycerin, polyethylene glycol, etc. are used. From the viewpoint of moldability, processability and densification of the raw sheet, the total amount of binder and plasticizer added to the raw sheet should be 4 to 4.
7% by weight is suitable. If the amount added is less than 4% by weight, cracks will occur in the green sheet. Also,
If the amount added is more than 7% by weight, the density of the sintered sheet,
Piezoelectric properties deteriorate. Since it is impossible to prevent raw sheets from cracking with organic binders and plasticizers alone,
In the present invention, a nonionic polyoxyethylene sorbitan fatty acid ester was further used as a dispersant, and polyethylene glycol was used as a wetting agent as a dispersion promoter. In the raw sheet, 1 to 2% by weight of the dispersant;
As for the wetting agent, the amount added is 3 to 4% by weight.
If the addition amount of either or both of them is decreased from the appropriate range, cracks will occur in the green sheet, and if they are increased, the adhesive strength of the binder will decrease, resulting in cracks in the green sheet. Regarding the solvent, a solvent containing alcohol as a main component which has good wettability with the piezoelectric ceramic material and 6% by volume of trichlorethylene added thereto to dissolve the polyoxyethylene sorbitan fatty acid ester was used. Add 35 parts by weight based on the weight part.
A slurry is made with these piezoelectric ceramic materials, a binder, a plasticizer, a dispersant, a wetting agent, and a solvent.

Pour this slurry onto a smooth substrate such as an organic film,
It is formed into a sheet of a certain thickness using the doctor blade method and dried to produce a smooth raw sheet. Next, the raw sheet is punched into the desired shape. The punched raw sheet contains organic components and is therefore easily charged with static electricity. Utilizing this property of being easily charged, a high melting point oxide powder, ie, zirconium oxide, magnesium oxide, aluminum oxide, or two or more thereof, is attached. In order to increase the amount of adhesion, since the organic binder and plasticizer have thermoplasticity, the green sheet may be heated to soften it. This method allows the high melting point oxide powder to be deposited in a short time.
These adhered powders make it possible to prevent fusion after sintering. Raw sheets with powder attached are laminated,
It is installed in an electric furnace and pre-fired at a temperature within the range of 250 to 3500° to remove organic components. At this time, at a temperature lower than 250 mm, the organic components cannot be removed sufficiently, so that cracks, warps, and deformations occur in the sintered sheet after main firing. Further, at a temperature higher than 35,000° C., although organic components can be removed, cracks, warping, and deformation occur during pre-firing. After pre-firing at a temperature within the range of 250 to 350 q0, it is slowly cooled to room temperature, and the pre-fired sheet is placed in a porcelain container containing magnesium oxide, aluminum oxide, zirconium oxide, or two or more thereof as a main component. Stack them into pods and seal them.

This is placed in an electric furnace and main firing is performed at a temperature within the range of 1,150 to 135,000 ℃. At this time, 11500○
At temperatures lower than that, sufficient sintering does not occur. Also, 1
At temperatures higher than 35,000 ℃, a composition shift occurs or it cannot decompose into a single phase. After the main firing is completed, the sintered body is cooled down to room temperature at an appropriate cooling rate and taken out from the furnace. The lead-based piezoelectric porcelain sintered sheet obtained by the present invention was highly homogeneous and had good smoothness.

Moreover, it is possible to perform laminated firing, has excellent mass productivity, and can be supplied at low cost. The piezoelectric composite sheet element thus obtained is useful for piezoelectric filters, piezoelectric buzzers, piezoelectric speakers, piezoelectric elements for auto-tracking of video tape recorders, and the like. Hereinafter, the present invention will be explained with reference to examples.

Example 1 The average particle diameter was about 0.81 m, Pbo. 9$
ro. 05 (Znl/3, Nb2/3) 0.10 (Sn
l/3, Nb2/3) 0.10Tio. 41Zro. 3
Binder 1 is added to the calcined raw material blended to have a composition ratio of 3.
．． 5-6% by weight, plasticizer 0.5-3% by weight, dispersant 0.
5 to 3% by weight of the wetting agent and 1 to 5% by weight of the wetting agent were weighed out (both are expressed as percentages in the raw sheet).

Further, as a solvent, alcohol containing 6% by volume of trichlorethylene was weighed out at a ratio of 35% by weight based on the calcined raw material. First, a dispersant and a solvent were added to the temporary bran raw material using a ball mill, and the mixture was mixed for 10 minutes, and then a wetting agent, a binder, and a plasticizer were added and mixed again for 24 hours. The kneaded product was poured onto a polyester film, formed into a sheet by a doctor blade method, and air-dried to produce a 1.0-thick willow green sheet. Table 1 shows its composition. Next, using a punching machine, each is punched out into a ring shape with 6 ribs on the outer diameter and 50 on the inner diameter side. Zirconium oxide powder with a particle size of approximately 5 m was filled into a component supply device having a vibration mechanism, and while heating at 7,000 ℃ from the bottom, a raw punched sheet was introduced into the device to adhere the zirconium oxide powder. This green sheet was layered horizontally in 10 layers, placed on an alumina substrate with a purity of 99.5% with a load applied for 3 days/day, placed in a furnace, and pre-fired as shown in Table 1. After removing organic components under the following conditions, main firing was performed under the firing conditions shown in Table 1. After firing, the Akatsuki compact was slowly cooled to room temperature and taken out. Although this burner sheet showed a shrinkage rate of 15 to 25% in the flea direction compared to the green sheet, it had excellent smoothness without cracking, warping, or deformation. Table 1 Example 2 PbTj03:PbZ 3 with an average particle diameter of 0.5 mm
:Pb(Mg1/3, Nb2/3)03=38:25:
The binder, plasticizer, and total amount added as shown in Table 2 were added to the temporary scale raw material blended to have a composition ratio of 4 to 6.
% by weight of a dispersing agent and a wetting agent were each added, 35% by weight of ethyl alcohol containing 6% by volume of trichlorethylene was added, and the mixture was thoroughly mixed to form a slurry.

Hereinafter, a raw sheet was prepared according to the same procedure as in Example 1,
Further, a sintered sheet was obtained under the preliminary firing conditions and main firing conditions shown in Table 2. These properties are shown in Table 2.
All had excellent smoothness with no cracks, warpage, or deformation. Table 2 As is clear from the above explanation, according to the method of the present invention, a thin raw sheet with a thickness of 0.5 to 2 legs using a fine lead-based piezoelectric material with an average particle diameter of 11 m or more can be produced. However, smooth and high-density piezoelectric crystalline sheets can be produced.

Claims (1)

[Claims] 1. A lead-containing piezoelectric raw material containing 3 to 5% by weight of a binder, 1 to 2% by weight of a plasticizer, 1 to 2% by weight of a dispersant, and 3 to 4% by weight of a wetting agent. After making a green sheet and punching it into a desired shape, the surface of the green sheet is heated in a high melting point oxide powder made of at least one of aluminum oxide, magnesium oxide, or zirconium oxide.
A method for manufacturing a piezoelectric sintered sheet, which comprises applying vibration to adhere the powder, stacking a single sheet or a plurality of sheets to remove organic components, and then sealing the sheet in a high melting point container and firing. 2. A method for producing a piezoelectric sintered sheet according to claim 1, characterized in that a single sheet or a plurality of raw sheets are stacked and pre-fired to remove organic components. 3. The method for producing a piezoelectric sintered sheet according to claim 1, wherein the main firing is performed at a temperature of 1150 to 1350°C.