JP2735148B2 - Micro-crack detection method by coloring indication - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a transparent conductive layer serving as an electrode, an electrochromic material layer whose color changes by a redox reaction of a material, a solid electrolyte, a polarized piezoelectric material layer and a transparent conductive layer. The present invention relates to a method for detecting a micro-crack by coloring, which is used to inspect a micro-crack generated in the detecting device by applying a material to the detecting device by a color change to check the fatigue of an aircraft body or equipment related to nuclear facilities.

[0002]

2. Description of the Related Art Conventionally, a method of detecting the occurrence of cracks in a metal plate or the like by applying ultrasonic vibration to an X-ray or a material to detect cracks and defects in holes is generally known. There is a law (acoustic emission method). In the AE method, when a solid is deformed or ruptured, the strain energy stored up to that time is released and becomes an acoustic pulse signal that propagates through the solid, and is a method for detecting the acoustic pulse signal. In this method, a large number of expensive AE sensors are required for finding crack locations, and the apparatus is complicated.
Not only was it large and expensive, but it could only be detected at the moment of crack initiation.

[0003]

However, it is difficult to detect minute cracks by the above-mentioned generally known detection method using X-rays and ultrasonic vibrations, and sufficient detection has not been performed. In addition, the AE method is complicated, large, and very expensive. Moreover, only the moment of the crack occurrence could be known.

[0004]

Means for Solving the Problems An electrochromic material layer that changes color by an oxidation-reduction reaction, a solid electrolyte layer of an ionic conductor, a piezoelectric material made of a polymer material or a semiconductor material, and a piezoelectric transverse effect on the piezoelectric material A material consisting of a piezoelectric material layer and a transparent conductive layer that has been subjected to polarization treatment so as to cause cracks is applied to the detection equipment, so that the detection is made by the color change of the oxidation-reduction reaction caused by the application of a voltage generated by micro cracks generated in the equipment. The present invention provides a method for detecting microcracks by coloring display, characterized by the following.

[0005]

According to the present invention, the electrode on the side of the piezoelectric material layer 1 on the detecting device 5 changes the color of the display surface on the transparent conductive layer 3 by the displacement of the piezoelectric material from the outside based on the oxidation-reduction reaction of the material by applying a voltage. Operates by an electrochemical mechanism. Considering oxidation and reduction of this material, oxidation is when the "valence = oxidation number" of the chemical species of interest increases in the positive direction, that is, when metal atoms lose extrashell atoms, the general formula Is expressed as follows.

[0006]

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[0007] Similarly, reduction corresponds to this reverse reaction and is expressed as follows.

[0008]

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That is, electrons enter and exit during both oxidation and reduction, and reactions between the electrons and the chemical species occur.

Here, considering the redox reaction of WO _3, a color change is caused by the following reaction.

[0011]

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Therefore, the tungsten oxide in the electrochromic material layer 4 is changed by the application of a voltage into tungsten bronze (M _x WO ₃ , M = Li ⁺ , H ⁺ ), and is proportional to the amount of electricity flowing. That is, coloring or decoloring is performed by the injected electrons or ions.

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an embodiment of a method for detecting micro-cracks by colored display according to the present invention, which will be specifically described below with reference to the drawings.

Reference numeral 1 denotes a piezoelectric material layer, which is a polymer material such as polyvinylidene fluoride (PVF ₂ ), zinc sulfide (ZnS),
Each of the piezoelectric semiconductor materials such as cadmium sulfide (CdS) is a powder paint, and is made of a material that generates a minute voltage by applying an external force to a polarized piezoelectric material, that is, a material having a piezoelectric effect. When a force (displacement) is applied to the piezoelectric material, an electric polarization proportional thereto is generated, and a dipole moment due to the polarization has a fixed direction. As an example, PVF ₂ or the like generates an electromotive force of several volts or more due to a strain force of 1 μm. That is, a crack generated in the equipment causes strain in the piezoelectric material, and as a result, a voltage proportional to the strain is generated. However, the deeper the crack, the higher the voltage. It has this piezoelectric material layer 1 and a solid electrolyte layer 2 such as polyethylene oxide (PEO) or antimonic acid.

The other electrode side is formed of a thin film of a paint such as ITO (indium tin oxide) or tin dioxide (SnO ₂ ) and formed on a transparent conductive layer 3 provided with a display surface by a color change. An electrochromic material such as tungsten oxide (WO ₃ ) is applied with a powder coating to form an electrochromic layer 4. The electrochromic layer 4 causes a color change by a redox reaction of tungsten oxide.

Further, a powder resistance R is provided between the two electrodes, and the coloring retention time can be adjusted by changing the resistance value.

[0017]

[Table 1]

Further, when ITO is used for the transparent conductive layer, it is necessary to apply a transparent insulating material to the surface as a measure against corrosion depending on the environment.

[0019]

As described above, according to the present invention, the cracking of a metal plate, which cannot be visually confirmed, can be easily detected by a color change by the detection method of the present invention (a crack of 1 μm or less which cannot be detected by X-ray or ultrasonic inspection). May be detectable).

Further, since it has a memory for retaining coloring, it is possible to detect even after the occurrence of cracks, which is a feature not found in the AE method. Also, if necessary, the color can be erased from outside. Further, the pulse voltage required for coloring is 0.5 V or less, and the current is about 2 μA.
Good contrast can be obtained if c / cm ^{2 is} about c).

Since the response speed is governed by the movement of ions, the response speed varies depending on the applied voltage, temperature, etc., but the response time for color erasing and erasing at 1 V operation is about 0.1 second at room temperature (as the temperature rises). Response time is shorter).

The repetition life is several million times or more, which is sufficient when used for crack detection.

[Brief description of the drawings]

FIG. 1 is a front view showing the configuration of a coating film in a method for detecting microcracks by coloring display according to the present invention.

FIG. 2 is a conceptual diagram of a coloring operation of the configuration of FIG. 1;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 piezoelectric material layer 2 solid electrolyte layer 3 transparent conductive layer 4 electrochromic material layer 5 detection equipment R powder resistance

Claims (1)

(57) [Claims] An electrochromic material layer that changes color by an oxidation-reduction reaction, a solid electrolyte layer of an ion conductor, a piezoelectric material made of a polymer material or a semiconductor material, and a piezoelectric transverse effect generated in the piezoelectric material. By applying a material consisting of a polarized piezoelectric material layer and a transparent conductive layer to the detection equipment, it is detected by the color change of the oxidation-reduction reaction due to the application of voltage generated by micro cracks generated in the equipment. Micro crack detection method by coloring indication.