JPS61287183A - Polarizing method for piezoelectric body material - Google Patents

Abstract

PURPOSE:To simplify operation, and to stabilize electric characteristics by polarizing a titanic acid-lead zirconic acid group piezoelectric body material by applying specific DC voltage in air. CONSTITUTION:Titanium acid-lead zirconium acid group piezoelectric materials, such as lead oxide, titanium oxide, zirconium oxide, zinc oxide, strontium oxide and niobium oxide are compounded and mixed, and dried and calcined and crushed, and methyl cellulose, glycerin and water are added to the crushed powder and kneaded, thus manufacturing a sheet in thickness such as 300mum or less through an extrusion method. The sheet is punched in a discoid manner, and baked and changed into a pellet-shaped sintered body, electrodes are formed on both surfaces, and the sintered body is set to a polarizing device and DC voltage of 3KV/mm or less is applied in air, thus executing polarization treatment. Accordingly, the piezoelectric body materials having stable electric characteristics can be acquired simply.

Description

Detailed Description of the Invention "Industrial Application Field" The present invention relates to a method for polarizing piezoelectric materials, which is particularly capable of obtaining stable piezoelectric properties in thin-walled piezoelectric ceramic materials, and which is suitable for processing operations. This relates to a simple polarization method.

"Conventional technology" Piezoelectric ceramic materials include lead, titanium, zirconium,
Although it is composed of oxides of zinc, strontium, niobium, etc., it is necessary to perform polarization treatment to improve the dielectric constant and electrical mechanical coupling coefficient. This polarization treatment usually involves immersing the piezoelectric material in an electrical insulator such as oil that has been heated to around 100°C to promote polarization.
A method of applying a DC voltage is used.

``Problem to be solved by the invention'' However, when the above-mentioned polarization process was performed, it was necessary to wash the piezoelectric material after polarization to remove oil, and it was also necessary to dry it. .

Furthermore, since the piezoelectric material is polarized in oil, complicated steps such as setting and taking out the piezoelectric material into an oil bath are required. In addition, the piezoelectric elements currently in practical use are generally small in shape and thin in wall thickness, so they are prone to chipping or cracking during handling, so the above polarization method is not suitable for industrial mass production. It wasn't necessarily suitable. Further, when the piezoelectric material is pipe-shaped, it is difficult to completely remove oil remaining in the pores, resulting in a lack of reliability.

SUMMARY OF THE INVENTION An object of the present invention is to provide a polarization method that eliminates the drawbacks of the prior art described above and that is easy to operate and that allows the production of a piezoelectric material with stable characteristics.

In order to achieve the above object, the present invention is characterized in that a piezoelectric material is polarized in air by applying a DC voltage of 3 KV/m or less. .

In the present invention, the piezoelectric material that can be polarized in air at room temperature is particularly suitable.

For example, piezoelectric materials that can be polarized relatively easily are suitable, such as piezoelectric materials made of lead oxide, titanium oxide, zirconium oxide, zinc oxide, and niobium oxide. Sunaochi,
For example, a piezoelectric material based on Pb(Ti, Zr)O, in which a portion of pb is replaced with Sr and a portion of Ti and Zr is replaced with Nb or Zn, is preferable because it can be polarized relatively easily.

Furthermore, in the present invention, if the DC voltage is too high, dielectric breakdown will occur, so the applied DC voltage is preferably 3 KV/- or less.

The shape of the piezoelectric material to which the present invention is applied has a thickness of 30 mm.
Desirably, the thickness is less than 0 μm; if the thickness of the piezoelectric material exceeds 300 μm, sufficient polarization will not be achieved. Also,
When the piezoelectric material is pipe-shaped, it is preferable to use a small one with a diameter of 0.5 to 5 m11 and a length of about 5 to 20 mm. Electrodes are formed on the inner and outer surfaces by plating, and each After attaching lead wires to the electrodes, a DC voltage is applied between the electrodes to polarize them. In this case as well, the thinner the piezoelectric material is, the easier it is to polarize.

Usually, the wall thickness is 50 to 500 μm, preferably 50 to 300 μm.

In addition, in the present invention, the polarization time, that is, the application time of the DC voltage, is preferably 2 minutes to 30 minutes. If the treatment time is shorter than 2 minutes, the polarization may be insufficient, and the aging treatment The dielectric constant etc. may decrease when conducting high-temperature tests or conducting high-temperature tests. On the other hand, in the case of a material having a wall thickness of the above-mentioned extent, a polarization treatment of 5 minutes is sufficient, and since an excessively long polarization treatment is rather disadvantageous industrially, the maximum length of the polarization treatment is 30 minutes.

"Example" The present invention will be described in more detail below based on an example.

<Example 1> Lead monoxide (pbo, Resurge A, manufactured by Mitsui Kinzoku Kogyo ■), titanium oxide (TiO2, KA-10 manufactured by Titanium Industries ■), and zirconium oxide (ZrO, manufactured by EP Rare Element ■) Zinc oxide (ZnO, Seido Kagaku 111111), strontium carbonate (S r COs v manufactured by Rare Metallic Co., Ltd.), and niobium oxide (Nb, O, manufactured by HPC Starck ■)
, Pba, ss Sro, 1sCZn1ysNb*
After blending and mixing to have a composition of yz>o, zsTio, *5Zro, 40m, it was dried, calcined at 850°C, and pulverized. Methyl cellulose (S M
-4000 (manufactured by Shin-Etsu Chemical) and glycerin (Wako Pure Chemical)
After adding water and kneading, sheets of various thicknesses (100.180° and 300 μm) were produced by extrusion. This was punched out into a disc shape with a diameter of 25+ am, and then fired at 1,280°C to obtain a pellet-shaped sintered body. Electrodes were formed by vapor-depositing gold and chromium on both sides of the obtained sintered body. Next, this was set in a polarizer and a DC voltage of 3 KV/- was applied for 5 minutes at 20°C in air. Then, polarization treatment was performed. The electrical properties of the obtained ferroelectric material are shown in Table 1.

Table 1 From these results, it can be seen that the electrical properties are good and polarization is sufficiently performed.

<Example 2> The 300μ sintered bodies produced in Example 1 were heated at 20°C to 1
The sample was annealed at a temperature of 00° C. for 2 hours, and then left at room temperature for 3 months. The results are as shown in Table 2.
The electrical properties of the sample aged at 80° C. did not change even after 3 months.

Table 2 ε8: Relative dielectric constant kp: Electromechanical coupling coefficient <Example 3> Materials calcined and kneaded in the same manner as in Example 1 were extruded to form a mold with an outer diameter of 1.5 mm and an inner diameter of 1.0 mm. (Wall thickness 250μm)
A pipe-shaped piezoelectric body with a length of 15 mm is molded, and this is
It was fired at 0°C. Electrodes were formed on the inner and outer surfaces of this sintered body by electroless plating, and lead wires were connected to the electrodes by soldering. Next, apply a DC voltage of 3 kV/mm in air to 5
After polarization was applied for a minute, it was aged at 65° C. for 2 hours. The electrical properties of the obtained pipe-shaped piezoelectric material were as follows: dielectric constant: 5,800. Its properties were stable with an electromechanical coupling coefficient of 61%.

"Effects of the Invention" As explained above, the present invention performs polarization treatment in air,
Furthermore, piezoelectric materials with stable electrical properties can be obtained by annealing at high temperatures if necessary, so compared to the conventional method of immersing in oil and polarizing, post-processes such as cleaning are not required. have Furthermore, the present invention has the effect that even a small pipe-shaped piezoelectric body can be easily polarized.

1985 Patent application No. 128760 Name of the invention Relationship to the case of a person who corrects the polarization method of piezoelectric material Patent applicant address 2-1-2 Marunouchi, Chiyoda-ku, Tokyo Name (5
08) Subject of Hitachi Metals Co., Ltd. amendment The "Claims" column and the "Detailed Description of the Invention" column of the specification.

Contents of the amendment As shown in the attached document, the contents of the amendment (■) and the statement in the "Claims" column of the specification are corrected as follows.

(1) A method for polarizing a piezoelectric material, which comprises polarizing a lead titanium tosylconate-based piezoelectric material by applying a DC voltage of 3 KV/u+ or less in air.

(2) In the polarization method according to claim 1,
The above piezoelectric materials are lead monoxide and titanium oxide.

A method for polarizing a piezoelectric material comprising zirconium oxide, zinc oxide, strontium oxide, and niobium oxide.

(3) A method for polarizing a piezoelectric material according to claim 1 or 2, characterized in that the piezoelectric material has a thickness of less than or equal to 10 mm.

(4) In the polarization method according to claim 1 or 2, the piezoelectric material has a pipe shape with a diameter of 0.5 to 5 ml and a length of 5 to 20 m+a, and electrodes are formed by plating. A method for polarizing a piezoelectric material, comprising: connecting lead wires after the polarization is performed.

(5) In the polarization method according to any one of claims 1 to 4, the temperature of the air atmosphere is 0 to 0.
A method for polarizing a piezoelectric material, characterized in that the temperature is 30°C.

(6) In the polarization method according to any one of claims 1 to 5, the temperature is 50 to 80°C after the polarization treatment.
"A method for polarizing a piezoelectric material characterized by aging at a temperature of 1 hour or more" (2) The description in the "Detailed Description of the Invention" column of the specification is corrected as follows.

1. Change "300μl" on page 4, line 18 to "700μ■"
Correct.

2) Correct "300μ蹹" on the same page to "700μ■".

3. "50-500μI" on page 5, line 6 is set to r50-2
im J to correct.

4. "50 to 300μIIJ to l"1μm on the same page
- Corrected to 111 J.

5, page 6, lines 12-13 [(100, 180, and 300 μn) J to r 100. 300 μm and 1 mm)].

6. Change the value in the first row of Table 1 on page 7 to ``180J'' to ``300J''.
” is corrected.

7. Correct the numerical value on the same page and table from "300" to "100".

that's all

Claims (6)

[Claims] (1) A method for polarizing a piezoelectric material, which comprises polarizing a lead titanate-zirconate-based piezoelectric material by applying a DC voltage of 3 KV/mm or less in air. (2) In the polarization method according to claim 1,
A method for polarizing a piezoelectric material, characterized in that the piezoelectric material is comprised of lead monoxide, titanium oxide, zirconium oxide, zinc oxide, strontium oxide, and niobium oxide. (3) A method for polarizing a piezoelectric material according to claim 1 or 2, wherein the piezoelectric material has a thickness of 300 μm or less. (4) In the polarization method according to claim 1 or 2, the piezoelectric material has a pipe shape with a diameter of 0.5 to 5 mm and a length of 5 to 20 mm, and an electrode is formed by plating. A method for polarizing a piezoelectric material, characterized in that a lead wire is connected after the polarization is performed. (5) In the polarization method according to any one of claims 1 to 4, the temperature of the air atmosphere is 0 to 0.
A method for polarizing a piezoelectric material, characterized in that the temperature is 30°C. (6) In the polarization method according to any one of claims 1 to 5, the temperature is 50 to 80°C after the polarization treatment.
A method for polarizing a piezoelectric material, characterized by aging at a temperature of 1 hour or more.