JPS58190081A - Sintering method for piezoelectric element - Google Patents

Abstract

PURPOSE:To enable to obtain piezoelectric elements of less dispersion by a method wherein setters provided with supporting grooves in a form of sectional inclination are arranged in a sintering sheath, and then plate formed molded bodies are arranged in a state of erection in a plurality in the supporting grooves, and supported at two points positioned higher than the lowermost part. CONSTITUTION:A plurality of the triangular-prismatic setters 5 consisting of Mg oxide, Al oxide, etc. are arranged at the bottom of the sintering sheath constituted of e.g. alumina or silica, and the supporting grooves in a form of sectional inclination formed between the setters 5 are formed. Further, spacers 6 for preventing the fall of the molded bodies are provided. Next, Pb(CCo1/2W1/2)0.08 (Ti0.47Zr0.45)O3 is compounded by a powder metallurgical method as the piezoelectric element to be sintered, then calcination is performed at 800 deg.C, and thus sample powdered bodies are obtained after grinding and drying. A small amount of binder of polyvinyl alcohol, etc. is added thereto, and accordingly the molded bodies 7 are obtained by using automatical press to 25phiX2mm. at the pressure of 0.8ton/cm<2>.

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention relates to a method for firing a piezoelectric element.

[Prior art and its problems]

Ultrasonic transducers and ceramic filters using piezoelectric elements are widely applied, but these
rO3-based materials, PbTi0. -PbZrOl-Pb(C
o +7°W1//l)0. Composite three-component material of PbTiOs, PbNb, 0.
Tungsten bronze molds such as B i, Ti, 0. Bismuth J-like compounds such as , etc. or their additives are used. When manufacturing a piezoelectric element such as a disc-shaped ultrasonic vibrator using these materials, a plurality of disc molded bodies (1) are used, as shown in the perspective view (a) and cross-sectional view fb in Fig. 1. are placed on an alumina or magnesia plate (2), and alumina bedding powder, magnesia bedding powder, or a similar material is placed between each compact to prevent fusion due to the reaction that occurs when the compact +11 is sintered. Firing was performed using the powder layer (3).

When a piezoelectric element fired using this method is used, for example, as an ultrasonic vibrator, it is said that the piezoelectric constant and dielectric constant vary greatly depending on the upper and lower positions of the sample due to the evaporation of PbO, Bi, 0°, etc. from the sample. There were drawbacks.

Further, this method has the disadvantage that it takes a lot of time to uniformly sprinkle the bedding powder between the molded bodies, and that it is necessary to remove the bedding powder even after firing.

Furthermore, since the bedding powder used in these methods is specially treated to prevent reactions between the molded bodies, there is also the drawback of increased costs. Furthermore, when the arrangement is carried out using this method, there is also the drawback that the stack of compacts tends to collapse even with the slightest vibration when handling the sintered pod (4), resulting in poor operability. Therefore, the stacking height is at most 2 diameters.
There was also a drawback that the sintered pod (4) had a low weight and had a bare limb per sintered pod (4).

[Purpose of the invention]

An object of the present invention is to improve the above-mentioned drawbacks and to provide a sintering force method capable of producing a disk vibrator and a piezoelectric element with less variation.

[Summary of the invention]

The present invention provides a center having a support groove with an inclined cross section,
The piezoelectric ceramic molded bodies are arranged upright in the support groove, and in a state where the molded bodies are supported, the lowest part of the outer circumference of the molded body is placed at two points higher than the lowermost part without coming into contact with the sintered sheath or center. An excellent piezoelectric element can be obtained by sintering the molded body with a spacer for supporting and preventing the molded body from falling over.

[Embodiments of the invention]

As shown in FIG. 2, a plurality of triangular prism-shaped centers (5) made of, for example, magnesium oxide, aluminum oxide, etc. are arranged on the bottom surface of a sintered pod made of, for example, alumina or silica, and between the centers (5), A support groove having an inclined cross section is formed. Furthermore, a spacer (6) was provided to prevent the molded body from falling over.

Next, as the piezoelectric element to be sintered, Pb (CC01AW)
QO8Tjo47Zrcna ) On was prepared by a powder metallurgy method, roasted at 800°C, pulverized, and dried to obtain a sample powder. A small amount of a binder such as polyvinyl alcohol was added to this, and a molded body (7) was obtained using an automatic press of 25φx2iut at a pressure of 0.8 ton/cIrL.

20 of these disc-shaped compacts were fired by the method of the present invention whose force is shown in Fig. 2, and their electromechanical coupling coefficient Kp
, and the values of the relative dielectric constant Cl/ε0 were determined.

The results are shown in Figure 83. For comparison, 20 sheets were similarly fired using the conventional firing method as shown in Figure 1, and their electromechanical coupling coefficient Kp and dielectric constant i were determined.
, H/g. The results are shown in Figure 4.

As is clear from FIGS. 3 and 4, in the conventional firing method, the variation in the coupling coefficient Kp relative permittivity is 5 to 10%, whereas in the method of the present invention, it is 1%.

As described above, by using the present invention, not only the fluctuations and fluctuations in piezoelectric characteristics can be reduced, but also the cost can be significantly reduced.

Furthermore, according to the sintering method of the present invention as described above, there are only two contact points with the center on the outer periphery that supports the molded body, and the electrode forming surface of the molded body contacts not only the sintered pod but also the center. Since the sintering can be performed without any reaction with the sintered sheath and center on the surface of the part, the original properties are not lost. Since the molding is carried out at two locations higher than the lowest point, the weight of the molded product itself is distributed over the two locations, the deformation of the molded product is greatly alleviated, and deterioration of the varistor characteristics can be prevented.

In the above embodiment, a triangular prism-shaped center was used as an example, and a disc-shaped one was used as a molded body.
As shown in the figure, one part is a flat part (8), and using a cylindrical center (9) with a partially cut out cross section, the flat part is placed inside the sintered pod QQl as shown in Figure 6. (8) Molding, for example, in the shape of a rectangular plate or disk, in the inclined support groove formed between the partially cut out cylindrical centers (9) in which a plurality of pieces are arranged at regular intervals so as to be in full contact with each other. A similar effect can be obtained by arranging a plurality of bodies αυ upright.

As described above, according to the present invention, when a compact is placed in a sintering pod and sintered, a center provided with a support groove having an inclined cross section is provided in the sintering pod, and the center is provided in the support groove. A plurality of plate-shaped molded bodies are arranged and supported in an upright state, and the lowermost part of the outer periphery of the molded body is supported at two locations higher than the lowermost part without coming into contact with the sintered sheath or center. This prevents characteristic deterioration and deformation and provides a piezoelectric element with stable characteristics.

[Brief explanation of the drawing]

1 and 6 are a perspective view and a sectional view of a conventional firing method, FIG. 2 is a perspective view of a firing method according to the present invention, and FIG. 3 is an electromechanical coupling coefficient Kp and a dielectric constant 6 according to the present invention.
Figure 4 is a curve diagram showing the values of each disc-shaped piezoelectric element of Φ/6°, and Figure 4 shows the values of the electromechanical coupling coefficient Kp J and relative dielectric constant ε, and I/ε0 of the disc-shaped piezoelectric element obtained by the conventional method. A curve diagram showing
FIG. 5 is a perspective view showing the security used in the present invention. 5.9... SEC 7.11... Molded body 6... Spacer agent Patent attorney Noriyuki Chika (and 1 other person) Figure 1 (D-2 Figure 2 Figure 8/ ?? 4577 j>'7 /dlf I?
l? 14f5tt17Qlriυ-nu Tamawaki Toharuka envy Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] A center provided with a support groove having an inclined cross section is provided, molded bodies made of piezoelectric ceramic are arranged vertically in the support groove, and while the molded bodies are supported, the lowest part of the outer periphery of the molded body is connected to the sintered body. A method for sintering a piezoelectric element, characterized in that the piezoelectric element is sintered by supporting it at two points higher than the lowermost part without contacting the sheath or the center, and by arranging a spacer to prevent the molded body from falling over.