JP3456108B2 - Piezoelectric element and method of manufacturing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric element used for, for example, a spark plug or a vibrator and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, an electrode is formed on opposite surfaces of a piezoelectric ceramic, one of the electrodes is marked with a marker for indicating the polarity of polarization, and then the electrode is placed on a polarization jig for polarization. Was there.

[0003]

In the above method, after polarization,
There is a problem that the marker disappears in a process such as washing, and the polarity cannot be discriminated.

Therefore, an object of the present invention is to provide a piezoelectric element whose polarity can be easily discriminated.

[0005]

In order to achieve this object, the piezoelectric element of the present invention comprises a piezoelectric ceramic, an electrode containing silver as a main component, which is provided on the facing surface of the piezoelectric ceramic, and an electrode of this electrode. It is provided with a silver chloride layer provided on at least a part of one of the electrodes, and the above object can be achieved by blackening the silver chloride layer.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention is directed to a piezoelectric ceramic, an electrode containing silver as a main component, which is provided on opposite surfaces of the piezoelectric ceramic, and one of the electrodes. A piezoelectric element including a silver chloride layer provided on at least a part of the piezoelectric element, and the polarization of the polarization of the piezoelectric element can be easily determined by blackening the silver chloride layer.

According to a second aspect of the present invention, the first step of forming an electrode containing silver as a main component on the opposing surfaces of the plate-shaped piezoelectric ceramics, and then the piezoelectric ceramics is placed on a polarization jig. A method for manufacturing a piezoelectric element, comprising a second step, and then a third step of forming a silver chloride layer by bringing one electrode of the piezoelectric ceramic into contact with an aqueous solution of hypochlorite to perform polarization. Since the polarity of polarization can be displayed with the piezoelectric ceramics installed on the polarization jig, there is no need to install the piezoelectric ceramics on the polarization jig by aligning the direction of the electrodes with different colors during polarization. Can be greatly improved.

The invention according to claim 3 is the method for manufacturing a piezoelectric element according to claim 2, wherein a hypochlorite solution having an effective chlorine content of 20 ppm or more is used, and a silver chloride layer can be easily formed. .

The invention according to claim 4 uses a hypochlorite solution containing at least one of calcium hypochlorite, sodium hypochlorite and potassium hypochlorite. The method of manufacturing a piezoelectric element according to No. 1, which is capable of forming a silver chloride layer on an electrode without corroding the silver electrode.

An embodiment of the present invention will be described below with reference to the drawings. (Embodiment 1) FIG. 1 is a side view of a piezoelectric element according to the present embodiment, in which 1 is a piezoelectric ceramic containing lead titanate zirconate as a main component, 2 is a facing silver electrode, and 3 is a facing silver electrode. 2 shows a silver chloride layer formed on the silver electrode on one side of FIG.

Next, a method of manufacturing the piezoelectric element shown in FIG. 1 will be described. Applying silver paste to both end surfaces of piezoelectric ceramics 1 processed to have a diameter of 2.5 mm and a length of 5 mm, and 600-
The silver electrodes 2 facing each other were formed by baking at 800 ° C. Next, the piezoelectric ceramic 1 having the silver electrodes 2 facing each other was placed on the polarization jig in which a spacer made of Teflon resin having a thickness of 4 mm and having a hole of 2.7 mm was provided on the copper plate. I set it up in the room. After that, on the upper surface of the piezoelectric ceramics 1, the silver electrode 2 has an effective chlorine content of 1000 ppm.
The aqueous solution of sodium hypochlorite was applied with a rubber roller having a cloth wrapped around the surface to form a silver chloride layer 3. The silver chloride phase formed at this time becomes black. Next, a copper plate is stacked on the silver electrode 2 of the piezoelectric ceramic 1 100
Immersed in silicone oil at ℃, 15k between upper and lower copper plates
A DC electric field of V was applied for 30 minutes to polarize the piezoelectric ceramic 1.

With the piezoelectric ceramics 1 installed on the polarization jig as described above, a silver chloride aqueous solution is applied to one side of the opposing silver electrode 2 to form a silver chloride layer 3 for polarization. Thus, it is possible to obtain a piezoelectric element in which the polarization of polarization is displayed with high productivity.

Here, the features of this piezoelectric element and its manufacturing method will be shown below.

(1) In this embodiment, lead zirconate titanate is used as the piezoelectric ceramic 1, but the same effect can be obtained with other piezoelectric ceramics such as lead titanate.

(2) In this embodiment, the silver chloride layer 3
Although an aqueous solution of sodium hypochlorite was used to form the above, any aqueous solution that forms the silver chloride layer 3 without corroding the silver electrode 2 may be used, such as calcium hypochlorite, sodium hypochlorite, An aqueous solution containing at least one kind of potassium hypochlorite may be used. However, since a mixed solution containing two or more kinds of the above hypochlorites is unstable, it is better to use an aqueous solution containing one kind of the above hypochlorites.

(3) The effective chlorine content of the aqueous solution of hypochlorite used for forming the silver chloride layer 3 on the silver electrode 2 is 20 p.
If it is less than pm, the silver chloride layer 3 formed is thin and the color is too light to discriminate the polarity of polarization.

(4) The effective chlorine content of the aqueous solution of the hypochlorite used to form the silver chloride layer 3 on the silver electrode 2 is 20 p.
Although it is necessary to have pm or more, it is preferable to use an aqueous solution of a hypochlorite having an effective chlorine amount of 100 ppm or more in order to reliably display a color for discriminating the polarity of polarization.

(5) In this embodiment, the silver chloride layer 3
Although it was formed before applying the DC voltage to the piezoelectric ceramics 1 of 1, the same effect can be obtained by forming the silver chloride layer 3 before applying the piezoelectric ceramics 1 from the polarization jig after applying the DC voltage. Since an insulating heat medium such as oil may adhere to the piezoelectric ceramics 1, there is a drawback that the silver chloride layer 3 is difficult to form.

(6) Although silicon oil is used as the insulating heat medium during polarization in the present embodiment, an insulating heat medium such as fluorine-based insulating oil or sulfur hexafluoride may be used.

(7) In this embodiment, the piezoelectric element having the silver electrodes 2 facing each other in the thickness direction has been described, but a piezoelectric element having the electrodes facing each other on the same plane also has the same effect.

(8) The silver chloride layer 3 may be formed on the entire surface of the silver electrode 2 or a part thereof, as long as the polarity can be selected.

However, when the silver electrode 2 is soldered, the silver chloride layer 3 cannot be soldered, and therefore the silver chloride layer 3 cannot be formed on the entire surface of the silver electrode 2.

[0023]

As described above, according to the present invention, a piezoelectric element capable of easily discriminating the polarity of polarization by forming a silver chloride layer on one surface of an opposing silver electrode of a piezoelectric ceramic and exhibiting a black color. Obtainable.

Further, since the piezoelectric element can display the polarity while being installed on the polarization jig, the productivity is improved.

[Brief description of drawings]

FIG. 1 is a side view of a piezoelectric element according to an embodiment of the present invention.

[Explanation of symbols]

1 Piezoelectric ceramics 2 Silver electrode 3 Silver chloride layer

Claims (4)

(57) [Claims] 1. A piezoelectric ceramic, an electrode containing silver as a main component, which is provided on opposite surfaces of the piezoelectric ceramic, and a silver chloride layer provided on at least a part of one of the electrodes. Piezoelectric element. 2. A first step of forming an electrode containing silver as a main component on opposite surfaces of a plate-shaped piezoelectric ceramic, a second step of setting the piezoelectric ceramic on a polarizing jig, and a second step of And a third step of forming a silver chloride layer by contacting one electrode of the piezoelectric ceramic with an aqueous solution of hypochlorite, and performing polarization. 3. The hypochlorite solution has an effective chlorine amount of 20 pp.
The method for manufacturing a piezoelectric element according to claim 2, wherein a piezoelectric element having a thickness of m or more is used. 4. The piezoelectric element according to claim 2, wherein the hypochlorite solution is a solution containing at least one kind of calcium hypochlorite, sodium hypochlorite and potassium hypochlorite. Production method.