JPH099394A - Ultrasonic wave element - Google Patents

Abstract

PURPOSE: To provide the ultrasonic wave element used even under an environment causing a wide range temperature change. CONSTITUTION: A metallic plate and a piezoelectric ceramics sintered body whose thermal expansion coefficients are largely different have a shim inbetween, whose thermal expansion coefficient is close to a thermal expansion coefficient of the piezoelectric ceramic sintered body and the shim and the metallic plate and the shim and a piezoelectric ceramic sintered body are adhered by using an adhesives with a high Young's modulus to obtain the ultrasonic wave element.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic element for oscillating or receiving an ultrasonic wave through a metal plate, and particularly to a structure in which a metal plate having a large thermal expansion coefficient and a piezoelectric ceramics sintered body are joined. It relates to an ultrasonic element.

[0002]

2. Description of the Related Art In recent years, piezoelectric ceramics sintered bodies have been widely used as ultrasonic oscillating elements or ultrasonic receiving elements.

Such an ultrasonic element is used when the atmosphere at the place of use adversely affects the piezoelectric ceramics sintered body, for example, when it is used in a corrosive gas atmosphere or when it is in contact with a corrosive fluid. In order to protect the piezoelectric ceramics sintered body, it was necessary to oscillate or receive a vibration through a metal plate having excellent corrosion resistance.

Here, the above-mentioned joining of the metal plate and the piezoelectric ceramics sintered body has not conventionally used an ultrasonic element under a severe temperature environment, and the piezoelectric ceramics sintered body itself has high strength. For this reason, a general organic adhesive, for example, an ultraviolet curable acrylate resin or the like is used to join the two to manufacture an ultrasonic element with a metal plate.

[0005]

However, in the ultrasonic element as described above, when the bonded metal plate and the piezoelectric ceramics sintered body have greatly different thermal expansion coefficients, the place of use When the temperature of changes greatly,
Due to the difference in coefficient of thermal expansion between the metal plate and the piezoelectric ceramics sintered body, a large shearing force acts on the bonding surface between the two, and the shearing force distorts the piezoelectric ceramics sintered body, resulting in the vibration characteristics originally possessed by the piezoelectric ceramics sintered body. In some cases, the shearing force may cause cracks in the piezoelectric ceramics sintered body, or the metal plate and the piezoelectric ceramics sintered body may separate, resulting in a state in which they cannot withstand use. There was also a case.

The present invention has been made in view of the problems of the above-described conventional ultrasonic element, and an object thereof is to provide an ultrasonic element which can be used even in an environment involving a wide range of temperature changes. Especially.

[0007]

In order to achieve the above-mentioned object, the present invention provides a piezoelectric ceramics sintered body with a metal plate and a piezoelectric ceramics sintered body, which have greatly different thermal expansion coefficients, between them. A structure in which a shim material having an approximate coefficient of thermal expansion is interposed, and the shim material and the metal plate and the shim material and the piezoelectric ceramics sintered body are joined with an adhesive having a high Young's modulus. Of ultrasonic element.

According to the ultrasonic element of the present invention described above, the metal plate and the piezoelectric ceramics sintered body, which are directly bonded to each other in the prior art, which differ greatly in thermal expansion coefficient, are disposed between the metal plate and the piezoelectric ceramics sintered body. Since the ultrasonic element has a structure in which a shim material having a thermal expansion coefficient close to that of the expansion coefficient is interposed, the metal plate is caused by a difference in thermal expansion coefficient when the ultrasonic element is subjected to a wide temperature change. The difference in elongation between the piezoelectric ceramic sintered body and the piezoelectric ceramic sintered body is relaxed by the shim material interposed therebetween, and the thermal expansion coefficient of the shim material approximates the thermal expansion coefficient of the piezoelectric ceramic sintered body. Therefore, at least the bonding surface between the piezoelectric ceramics sintered body and the shim material has a structure in which shearing force is hard to work,
Even when used in an environment with a wide range of temperature changes, the piezoelectric ceramic sintered body has an effect of becoming an ultrasonic element in which distortion or cracks hardly occur.

Further, in the above-mentioned present invention, the shim material interposed between the metal plate and the piezoelectric ceramics sintered body is formed of an adhesive having a high Young's modulus, that is, an adhesive having a high hardness which is not easily deformed. Since the structure is such that the adhesive is bonded to the plate and the ceramics sintered body, the adhesive does not affect the vibration of the piezoelectric ceramics sintered body or the vibration of the metal plate, and the ultrasonic wave can be accurately oscillated or received. It has the function of becoming an ultrasonic element.

The shim material is 0.9 to 5.0 ×.
It is preferable to use a shim material having a coefficient of thermal expansion of 10 ⁻⁶ / ° C. This is because the piezoelectric ceramics sintered body generally used for ultrasonic elements is a lead zirconate titanate-based (hereinafter,
(PZT-based) ceramics, and the coefficient of thermal expansion of this ceramics is about 3 × 10 ⁻⁶ / ° C., so that a shim material having a coefficient of thermal expansion in the above range approximate to this coefficient of thermal expansion Preferably. If the temperature deviates from the above range, a large shear force due to the difference in coefficient of thermal expansion acts on the bonding surface between the piezoelectric ceramic sintered body and the shim material when subjected to a wide range of temperature changes, and this shear force causes the piezoelectric ceramics to burn. It is not preferable because the possibility of distortion or cracks in the bonded body increases. Examples of the material of the shim material having the thermal expansion coefficient within the above range include 42 alloy, invar (invar), spar invar (spar amba), and metal such as kovar.

The above-mentioned adhesive is 40 to 150 kgf / m
An adhesive having a Young's modulus of m ² is preferable. This is because the Young's modulus adhesive of less than 40 kgf / mm ²
This is because the adhesive greatly attenuates the vibration of the piezoelectric ceramics sintered body or the vibration of the metal plate, and the ultrasonic element cannot accurately oscillate or receive ultrasonic waves. An adhesive with a Young's modulus exceeding kgf / mm ² is too hard and the adhesive reduces the vibration displacement of the piezoelectric ceramics sintered body or the vibration of the metal plate, and only weak oscillation or vibration can be received. This is because it becomes an ultrasonic element. As the adhesive having a Young's modulus in the above range, an anaerobic modified acrylate resin (manufactured by Nippon Loctite Co., Ltd .: Loctite 272),
Alternatively, a low stress epoxy resin (Epicote 806 manufactured by Yuka Shell Epoxy Co., Ltd.) and the like can be mentioned.

[0012]

[Test Example] A test example supporting the effect of the ultrasonic element according to the present invention will be described below.

Diameter 8m made of PZT ceramics
Piezoelectric ceramics sintered body of m, thickness 1.5mm, and SUS3
The metal plate having a diameter of 10 mm and a thickness of 0.7 mm manufactured in Example 16 was joined by the methods of Test Examples 1 to 7 described below. The thermal expansion coefficient of PZT ceramics is 3 × 10 ^-6 /
℃, the thermal expansion coefficient of SUS316 is 17 × 10 ^-6
/ It is about ℃.

-Test Example 1-A shim material having a diameter of 10 mm and a thickness of 0.7 mm manufactured by a spar invar is interposed between the piezoelectric ceramic sintered body and the metal plate, and the shim material and the above An anaerobic modified acrylate resin (Nippon Loctite KK: Loctite 272) was bonded to the piezoelectric ceramic sintered body and to the shim material and the metal plate. The joining conditions were two-step curing of 10 kg / cm ² under pressure and heating at 130 ° C. for 4 minutes, and then under heating at 130 ° C. for 30 minutes. Also, the coefficient of thermal expansion of the spar invar (spar amba) used as the shim material is 1 × 10 ⁻⁶ /
The above Loctite used as an adhesive
The Young's modulus of 272 is about 60 kgf / mm ² .

Test Example 2 A shim material having a diameter of 10 mm and a thickness of 0.7 mm manufactured from 42 alloy is interposed between the piezoelectric ceramic sintered body and the metal plate, and the shim material and the piezoelectric ceramic are used. The Loctite 272 similar to that used in Test Example 1 was used to join the sintered body and the shim member to the metal plate. The joining conditions were the same as in Test Example 1 above. The coefficient of thermal expansion of the 42 alloy used as the shim material is 4 ×
It is about 10 ^-6 / ℃.

Test Example 3 A shim member having a diameter of 10 mm and a thickness of 0.7 mm manufactured by the same spar invar as in Test Example 1 is interposed between the piezoelectric ceramics sintered body and the metal plate. The shim material and the piezoelectric ceramics sintered body, and the shim material and the metal plate were joined with a low stress epoxy resin (Yukaka Shell Epoxy Co., Ltd .: Epicoat 806). In addition, the joining condition is 2 under heating at 100 ° C.
Two-stage curing was performed for 4 hours under heating at 150 ° C. for 4 hours. The Young's modulus of the Epicoat 806 used as the adhesive is about 150 kgf / mm ² .

Test Example 4 A shim material made of phosphor bronze and having a diameter of 10 mm and a thickness of 0.7 mm is interposed between the piezoelectric ceramic sintered body and the metal plate, and the shim material and the piezoelectric ceramic are used. Between the sintered body,
Then, the shim material and the metal plate were joined together using the same Loctite 272 as in Test Example 1. The joining conditions are 10 kg / cm ² and 4 under pressure and heating at 130 ° C.
Min, 10 minutes under heating at 130 ° C, and 150 ° C
Under 10 minutes of three-stage curing. Also,
The coefficient of thermal expansion of the phosphor bronze used as the shim material is 1
It is about 7 × 10 ^-6 / ° C.

Test Example 5 A shim material having a diameter of 10 mm and a thickness of 0.7 mm manufactured by the same spar invar (spar umber) as in Test Example 1 is interposed between the piezoelectric ceramic sintered body and the metal plate. The shim material and the piezoelectric ceramics sintered body, and the shim material and the metal plate were joined with an anaerobic modified acrylate resin (Nippon Loctite KK: Loctite 620). The joining conditions were the same as in Test Example 4 above. The Young's modulus of Loctite 620 used as an adhesive is about 35 kgf / mm ² .

Test Example 6 A shim material having a diameter of 10 mm and a thickness of 0.7 mm manufactured by the same spar invar (spar umber) as in Test Example 1 is interposed between the piezoelectric ceramic sintered body and the metal plate. The shim material and the piezoelectric ceramics sintered body and the shim material and the metal plate were bonded together with an epoxy resin. In addition,
The bonding conditions were 2 kg / cm ² and 100 ° C. under pressure and heating for 2 hours. The Young's modulus of the epoxy resin used as the adhesive is about 180 kgf / mm ² .

Test Example 7 The above piezoelectric ceramics sintered body and the metal plate were directly bonded with an ultraviolet-curable acrylate resin (Nippon Loctite Co., Ltd .: LID-1316) without using a shim material. The bonding conditions were 4 kg / cm ² , under pressure and heating at 105 ° C. for 50 seconds, and then UV irradiation intensity of 150 mW / cm ² for 3 seconds.
It was irradiated with ultraviolet rays for 0 seconds.

Each ultrasonic element bonded by the method of Test Examples 1 to 7 was placed on a hot plate heated to 130 ° C., 150 ° C., and 200 ° C. for 5 minutes each, and then each ultrasonic wave. The presence or absence of abnormality of the device was judged. It should be noted that the presence / absence of abnormality is determined by the presence / absence of appearance abnormality such as peeling or cracking, and the impedance phase gain analyzer (Yokogawa / Purette / Packard Co., Ltd .: 4194A) does not generate spurious. It was judged whether or not. Table 1 shows the results.

[0022]

[Table 1]

From Table 1, a shim material having a coefficient of thermal expansion close to that of the piezoelectric ceramics sintered body is interposed between the piezoelectric ceramics sintered body and the metal plate, and the shim material and the metal plate. , And the case where the shim material and the piezoelectric ceramics sintered body are respectively joined with an adhesive having a high Young's modulus (Test Examples 1 to 3), an ultrasonic element capable of withstanding a wide range of temperature changes. It turns out that On the other hand, when the thermal expansion coefficient of the shim material interposed between the piezoelectric ceramics sintered body and the metal plate is not close to the thermal expansion coefficient of the piezoelectric ceramics sintered body (Test Example 4), or It can be seen that if the used adhesive has a low Young's modulus (Test Example 5) or is too high (Test Example 6), some abnormality occurs in the ultrasonic element when subjected to a wide temperature change. .

[0024]

As described above, the ultrasonic element according to the present invention described above has an effect of becoming an ultrasonic element capable of exhibiting the vibration characteristics originally possessed by the piezoelectric ceramics sintered body even when subjected to a wide range of temperature changes. .

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Claims (3)

[Claims] 1. A shim material having a thermal expansion coefficient close to that of a piezoelectric ceramics sintered body is interposed between a metal plate and a piezoelectric ceramics sintered body having a large thermal expansion coefficient, and the shim material is provided. An ultrasonic element having a structure in which an adhesive having a high Young's modulus is connected between the metal plate and the metal plate, and between the shim material and the piezoelectric ceramics sintered body. 2. The coefficient of thermal expansion of the shim material is 0.9 to
The ultrasonic element according to claim 1, wherein the ultrasonic element has a temperature of 5.0 × 10 ^-6 / ° C. 3. The Young's modulus of the adhesive is 40 to 150.
3. The ultrasonic element according to claim 1, wherein the ultrasonic element is kgf / mm ² .