JP2010271319A - Waveguide ultrasonic sensor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a simple structured waveguide ultrasonic sensor device which increases a phase velocity, while increasing a bandwidth of incident frequency with a fixed group velocity to improve visualization performance of ultrasonic wave. <P>SOLUTION: The waveguide ultrasonic sensor device includes an ultrasonic sensor 10 which transmits and receives ultrasonic signal to an object, wedge 20 supporting one side of the ultrasonic sensor 10 to switch modes of the ultrasonic signal, a waveguide 30 arranged between the wedge 20 and the object to guide the transmitted and received ultrasonic signal, and a high power ultrasound system 50 for processing the transmitted and received ultrasonic signal. A coating layer made of aluminum oxide (Al<SB>2</SB>O<SB>3</SB>) and/or beryllium (Be) is provided on at least part of external surface on the waveguide. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a waveguide ultrasonic sensor device according to the present invention, and more particularly to a waveguide ultrasonic sensor device capable of improving visualization performance via an ultrasonic signal guided and radiated through the waveguide.

  Since internal structures in extreme environments such as sodium that are opaque and hot can be damaged by high temperature clippy, such damage appears as fine surface defects on the surface of the internal structure. By the way, it is difficult for the internal structure in the extreme environment as described above to inspect minute surface defects with naked eyes due to extreme factors such as opaqueness, high temperature, and high radioactivity. Therefore, a method of using an ultrasonic sensor is generally employed as a method for inspecting defects in internal structures in an extreme environment.

There are two methods for visualizing internal structures using an ultrasonic sensor: a method in which an ultrasonic sensor is directly immersed in sodium and an inspection is performed, and an ultrasonic sensor is provided outside and a stainless steel plate waveguide is used. is divided into the waveguide ultrasonic sensor method for transmitting and receiving the Lamb waves a ₀ mode is a Lamb wave follows antisymmetric (Lamb wave). Among these, the ultrasonic sensor method based on the direct immersion has a problem that the life of the ultrasonic sensor is shortened by contacting the ultrasonic sensor with the liquid metal in the extreme environment. On the other hand, in the wave guide ultrasonic sensor method, the ultrasonic sensor transmits and receives an ultrasonic signal remotely using a waveguide of an elongated metal plate having a length of 5 m or more outside the liquid metal, and the ultrasonic wave according to the conveyance position of the ultrasonic sensor. By adopting the C-scan visualization method that expresses the magnitude of the signal amplitude and the time difference between radio waves, there is an advantage that the shortening of the life, which is a problem of the ultrasonic sensor method by liquid immersion, can be directly compensated.

Here, when an SS304 stainless steel waveguide having a thickness of 1 mm is employed, the phase velocity (C _ph ) of the A ₀ mode Lamb wave at an incident frequency of 1.5 MHz is about 2.6 m / ms. The longitudinal wave velocity (V _L ) of the lucite solid wedge is smaller than 2.7 m / ms. Thus, in order to oscillate the Lamb waves A ₀ mode through the waveguide, the couplant liquid inside wedge inevitably applies filled liquid wedge.

On the other hand, in applying the waveguide ultrasonic sensor method, group velocity in order to minimize the occurrence of dispersion of the Lamb waves A ₀ mode must vibrate the incident wave in a certain frequency domain. Since an ultrasonic pulse propagated from a frequency band with a constant group velocity is minimized in dispersibility, the pulse waveform does not change, so the S / N ratio is improved, and the emission angle of the leaky longitudinal wave beam Since no change occurs, the beam pre-file becomes uniform.

Moreover, the increase in the frequency bandwidth of the incident wave by the dispersion occur at the waveguide ultrasonic sensors above 5m the long-range radio waves A ₀ mode Lamb waves, leakage longitudinal emitted out of liquid metal, such as sodium A beam divergence phenomenon occurs due to an increase in the change width of the wave beam emission angle. If the divergence angle of such a beam divergence phenomenon is increased, the resolution is lowered. Thus, in order to realize a C- scan ultrasound image of high resolution, the group velocity of the Lamb wave of the A ₀ mode propagating in the waveguide sensor has to achieve very constant properties. Further, in order to increase the angle switching range of the radiation beam leaks longitudinal waves in in a liquid metal such as sodium, the group velocity of the Lamb wave of the A ₀ mode only possible phase velocity at a fixed frequency band It must change a lot. Thus, in the frequency band where the group velocity of the Lamb wave of the A ₀ mode is fixed, the need to develop a new wave guide sensor phase velocity varies greatly persistently request.

In conclusion, the phase velocity (C _ph ) of the A ₀ mode propagating by the waveguide ultrasonic sensor is the wedge longitudinal wave velocity (V _L = 2.7 m / ms) and sodium longitudinal wave velocity (V _L = 2). Larger than .474 m / ms), the group velocity of Lamb waves in the A ₀ mode propagating through the waveguide in the excitation pulse excitation frequency range (0.8 MHz to 1.7 MHz) is constant, and constant incidence research / development is being asked for implementing the a ₀ mode Lamb wave phase velocity difference is large waveguide ultrasonic sensor device of the extent of the wave excitation frequency.

  The object of the present invention has been devised in view of the above-mentioned problems, and increases the phase velocity with a simple structure and increases the bandwidth of the incident frequency with a constant group velocity. An object of the present invention is to provide a waveguide ultrasonic sensor device capable of improving the visualization performance of ultrasonic waves.

  Another object of the present invention is to provide a waveguide ultrasonic sensor device capable of realizing a phase velocity larger than the longitudinal wave velocity of a solid wedge.

  A waveguide ultrasonic sensor apparatus for achieving the above-described object includes an ultrasonic sensor, a wedge, a waveguide, and a high-power ultrasonic system.

  The ultrasonic sensor transmits / receives an ultrasonic signal to / from an object placed in an extreme environment, and the wedge supports one side of the ultrasonic sensor and switches a mode of the ultrasonic signal. At this time, the wedge is preferably formed into a solid.

The waveguide is provided between a wedge and the object, and guides the transmitted and received ultrasonic signals. Here, a coating layer formed of aluminum oxide (Al ₂ O ₃ ) and / or beryllium (Be) is provided on at least a part of the outer surface of the waveguide.

  More specifically, the coating layer is provided symmetrically on one side and the other side across the waveguide, or is asymmetric only on one side or the other side of the waveguide. Provided and has a thickness of 0.125 mm to 0.25 mm. The waveguide provided with such a coding layer is preferably formed on a stainless steel plate, has a length of 5 m or more, and a thickness of 1 mm to 2 mm.

  The high-power ultrasound system processes and visualizes the transmitted and received ultrasound signals.

A waveguide ultrasonic sensor device according to another aspect of the present invention is for visualizing the state of an object placed in a high temperature, high radioactivity and / or opaque extreme environment as an ultrasonic signal. Aluminum oxide (Al ₂ O ₃ ) that is provided between an ultrasonic sensor that transmits and receives a sound wave signal and an object, increases the phase velocity on the outer surface of the waveguide that guides the ultrasonic signal, and maintains the group velocity constant. And / or a coating layer formed of beryllium (Be).

According to the present invention having the above-described configuration, first, the wave guide is formed by providing a coating layer formed of aluminum oxide (Al ₂ O ₃ ) and / or beryllium (Be) on the outer surface of the waveguide. group velocity of the Lamb wave of a ₀ modes propagated to expand the certain frequency regions along the guide. This can minimize the occurrence of A ₀ mode Lamb wave dispersion which is long distance propagation through a waveguide having a length more than 5 m, to minimize the waveform distortion of the incident wave.

Second, the bandwidth of the frequency spectrum of the incident pulse of long-distance A ₀ mode Lamb wave through the waveguide a coating layer formed of aluminum oxide (Al 2 _{O 3)} and / or beryllium (Be) is provided The increase and the beam divergence angle of the leakage longitudinal wave can be minimized, and the ultrasonic visualization resolution can be improved.

Thirdly, the coating layer formed of aluminum oxide (Al ₂ O ₃ ) and / or beryllium (Be) has a phase velocity of Lamb wave in A ₀ mode larger than the longitudinal wave velocity of the wedge formed in the solid. It is possible to increase the frequency range where the group velocity is constant. This makes it possible to use wedges formed into solids that can be used for a long time in high temperature environments, improving the life of the waveguide ultrasonic sensor device and switching the angle of the radiation beam of longitudinal leakage waves in liquid metal It has the advantage of increasing the range so that the radiation beam steering function can operate normally over long distances of 5 m or more.

1 is a conceptual diagram schematically showing a nuclear reactor in which a waveguide ultrasonic sensor device according to a preferred embodiment of the present invention is employed. It is a block diagram which shows schematically the waveguide ultrasonic sensor apparatus by this invention shown by FIG. Lamb waves of S ₀ mode Lamb wave and A ₀ mode which is propagated along the waveguide is a diagram schematically showing. Lamb waves of S ₀ mode Lamb wave and A ₀ mode which is propagated along the waveguide is a diagram schematically showing. It is a figure which shows schematically the state by which the coating layer was equipped with the asymmetrical type and the symmetrical type in the waveguide. It is a figure which shows schematically the state by which the coating layer was equipped with the asymmetrical type and the symmetrical type in the waveguide. It is a figure for demonstrating the state by which an ultrasonic signal is radiated | emitted by the other end of a waveguide. Is a graph curve is shown of the dispersion characteristics of phase velocity and group velocity of the Lamb wave thickness by A ₀ mode waveguide. Is a graph curve is shown of the dispersion characteristics of phase velocity and group velocity of the Lamb wave thickness by A ₀ mode waveguide. Curve of the dispersion characteristics of phase velocity and group velocity of the Lamb wave of the A ₀ mode waveguide which coating layer is provided with a graph shown. Curve of the dispersion characteristics of phase velocity and group velocity of the Lamb wave of the A ₀ mode waveguide which coating layer is provided with a graph shown. Curve of the dispersion characteristics of phase velocity and group velocity of the Lamb wave of the A ₀ mode thickness different waveguides of the coating layer is a graph shown. Curve of the dispersion characteristics of phase velocity and group velocity of the Lamb wave of the A ₀ mode thickness different waveguides of the coating layer is a graph shown. Is a graph curve of the dispersion characteristics of phase velocity and group velocity of the asymmetric / symmetric Lamb wave of the wave guide A ₀ modes coating layer provided for are shown. Is a graph curve of the dispersion characteristics of phase velocity and group velocity of the asymmetric / symmetric Lamb wave of the wave guide A ₀ modes coating layer provided for are shown. It is a graph by which the radiation angle of a leaking longitudinal wave is shown.

  Hereinafter, a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

  Referring to FIGS. 1 and 2, a waveguide ultrasonic sensor device 1 according to the present invention includes an ultrasonic sensor 10, a wedge 20, a waveguide 30, and a high-power ultrasonic system 50.

  For reference, as shown in FIG. 1, a waveguide ultrasonic sensor device 1 according to an embodiment of the present invention directly uses a ultrasonic signal such as a liquid metal furnace, a lead-cooled reactor, an integrated nuclear reactor, and the like. Remote ultrasonic visualization inspection is performed on internal structures (O, hereinafter referred to as “objects”) in an extreme environment that is difficult to approach. In the present embodiment, the object (O) is exemplified as being immersed in a nuclear reactor (N) in which a liquid metal (L) such as sodium is received.

  Such a waveguide ultrasonic sensor device 1 is not shown in detail, but is fixed to a double rotating plug (not shown) of a head (H) provided at the upper part of the nuclear reactor (N). H) protrudes to the outside, and the lower part faces the upper end of the core of the object (O). With such a configuration, the waveguide ultrasonic sensor device 1 can detect the object (from the ultrasonic signal collected during the rotational driving of the double rotary plug (not shown) provided in the head (H)) and the position information of the ultrasonic sensor. Acquire a C-scan image (I) of the upper end of the core which is O).

  The aforementioned waveguide ultrasonic sensor device 1 will be described in more detail with reference to FIG.

  First, the ultrasonic sensor 10 transmits an ultrasonic signal to the object (O) or receives an ultrasonic signal reflected from the object (O).

  The wedge 20 is provided to support one side of the ultrasonic sensor 10 and switches the mode of the ultrasonic signal. Specifically, the wedge 20 switches the ultrasonic signal transmitted from the ultrasonic sensor 10 to a lamb wave, or switches the lamb wave received via the waveguide 30 described later to a longitudinal wave. That is, when the ultrasonic signal transmitted / received by the ultrasonic sensor 10 passes through the wedge 20, the mode is switched to the Lamb wave or the longitudinal wave. In the present embodiment, the wedge 20 is illustrated as being formed into a solid, and more preferably as a lucite.

For reference, a Lamb wave refers to a wave traveling in a thin plate-like solid. As shown in FIG. 3, a symmetric mode (S-Mode) and an antisymmetric mode (A -Mode). As shown in FIG. 3A, in the symmetric mode Lamb wave (S-Mode), the wave component oscillating in the traveling direction is symmetric with respect to the center line (C) of the plate thickness, or as shown in FIG. The anti-symmetric mode Lamb wave (A-Mode) is asymmetric. In the present embodiment, it is exemplified that the 0th-order antisymmetric Lamb wave (A ₀ ) shown in FIG. 3B is used from Lamb waves of various modes. Hereinafter, for convenience of explanation, a 0th-order antisymmetric Lamb wave (A ₀ ) whose mode is switched by the wedge 20 is referred to as an A ₀ mode Lamb wave.

The wave guide 30 is provided between the ultrasonic sensor 10 and the object (O), and guides an ultrasonic signal to be transmitted and received. Specifically, as shown in the figure, one end of the waveguide 30 is connected to a wedge 20 that supports one side of the ultrasonic sensor 10 outside the reactor (N), and the other end is received by the reactor (N). It is immersed in the liquid metal (L) to be faced with the object (O). Thus, Lamb waves A ₀ mode is switched by being radiated wedge 20 from the ultrasonic sensor 10 is propagated in the longitudinal direction of the wave guide 30, is guided to the subject (O). Such a waveguide 30 is formed in a long and narrow stainless steel plate having a thickness of 1 mm to 2 mm and a length of 5 m or more.

On the other hand, as shown in FIG. 4, a coating layer 40 formed of aluminum oxide (Al ₂ O ₃ ) or beryllium (Be) is provided on the outer surface of the waveguide 30 according to the present invention. Here, the coating layer 40 is formed in an asymmetric shape provided only on one side of the outer surface of the waveguide 30 as shown in FIG. 4A, or on both sides of the outer surface of the waveguide 30 as shown in FIG. 4B. It may be formed symmetrically. Further, the coating layer 40 may be formed on at least a part of the outer surface such as the radiation end of the waveguide 30.

The coating layer 40 on the nature of the material to expand a certain frequency region of the group velocity of the Lamb wave of the A ₀ mode. This can minimize the occurrence of A ₀ mode Lamb wave dispersion which is long distance propagation through a waveguide 30 having a length more than 5 m, to minimize the waveform distortion of the incident wave. Further, by minimizing the increase and beam divergence of leakage longitudinal band width of the frequency spectrum of the incident pulse of radio waves of the Lamb waves of long distance A ₀ mode through the waveguide 30, improves the visualization resolution ultrasound Let

In addition, the coating layer 40 increases the phase velocity of the A ₀ mode Lamb wave to the longitudinal wave velocity of the wedge 20 formed in the solid, and the phase velocity and the magnitude change in the frequency region where the group velocity is constant. Increase range. As a result, it becomes possible to use the wedge 20 formed into a solid that can be used for a long time in a high-temperature environment, to improve the life of the waveguide ultrasonic sensor device 1 and to emit a leakage longitudinal wave radiation beam in the liquid metal (L). By increasing the angle switching range, there is an advantage that the steering function of the radiation beam can be normally operated even for a long distance of 5 m or more.

That is, by providing the coating layer 40 formed of aluminum oxide (Al ₂ O ₃ ) or beryllium (Be) on the outer surface of the waveguide 30 as described above, the phase velocity and group velocity of the A ₀ mode Lamb wave The constant frequency region is increased to improve the radio wave performance of A ₀ mode Lamb waves and the radiation angle switching performance of leaky longitudinal waves.

  The high-power ultrasound system 50 includes a high-power ultrasound pulser / receiver 51 and a computer 53 by processing and visualizing transmitted and received ultrasound signals.

  The high-power ultrasonic pulsar / receiver 51 is connected to the ultrasonic sensor 10 to generate an ultrasonic signal transmitted to the object (O), and is reflected from the object (O) and received by the ultrasonic sensor 10. An ultrasonic signal is provided. At this time, the high output ultrasonic pulsar / receiver 51 adjusts the frequency of the incident pulse to generate an ultrasonic signal, and collects the ultrasonic signal received with the surface information of the object (O). On the other hand, the ultrasonic signal collected by the high-power ultrasonic pulser / receiver 51 is measured by the oscilloscope 52, switched to a digital signal by the A / D converter 54, and controlled by the computer 53.

  For reference, the ultrasonic sensor 10 is controlled by the scanner controller 60 separately from the high-power ultrasonic system 50 (see FIG. 1).

The 5 vertically leaking into the liquid metal (L) via the radio wave A ₀ mode Lamb waves which via a wave guide 30 connected to the wedge 20 which supports the ultrasonic sensor 10, the other end of the waveguide 30 A conceptual diagram of the wave breaking out is shown.

As shown in FIG. 5, the leakage to the longitudinal waves Lamb waves A ₀ modes propagated by the waveguide 30 is in contact with the liquid metal (L), this time, the beam emission angle leakage longitudinal wave (alpha) is the following It is determined according to the Snell law of Formula 1.

Here, V _L is the longitudinal velocity of the liquid metal (L), C _ph is the phase velocity of the Lamb wave in the A ₀ mode, and f is the frequency. For reference, the waveguide 30 is formed on an SS304 stainless steel plate having a thickness of 1 mm, an ultrasonic signal of 1.5 MHz is incident on the waveguide 30, the phase velocity of the A ₀ mode Lamb wave and the liquid metal (L) When the longitudinal wave velocities are about 2560 m / s and 2474 m / s, respectively, the beam radiation angle (α) of the leaky longitudinal wave is about 75 degrees according to Equation 1.

Referring to FIGS. 6 and 7, the phase velocity (C _ph ) of the A ₀ mode Lamb wave according to the thickness (t) of the waveguide 30 in the liquid metal (L) formed of sodium, and the group velocity ( A curve of the dispersion characteristic of _Cg ) is shown. In order to apply the long-distance waveguide 30 having a length of 5 m or more to the liquid metal (L) containing sodium, the phase velocity (C _ph ) of the A ₀ mode Lamb wave is that of the sodium liquid metal (L). If the longitudinal wave velocity (V _L ) is not larger than 2474 m / s, the mode is switched to the leaky longitudinal wave and the ultrasonic beam cannot be emitted through the other end of the waveguide 30. Here, the ultrasonic sensor 10 mainly used in the waveguide ultrasonic sensor device 1 is a 1 MHz sensor and a 1.5 MHz sensor, and the frequency band mainly used for the excitation frequency of the ton burst incident wave is 0.8 MHz. ~ 1.7 MHz. The group velocity (C _g ) must be constant as shown in FIG. 7 in the 0.8 MHz to 1.7 MHz band, which is the range of the excitation frequency of the incident wave, and the phase velocity has a magnitude as shown in FIG. The width of change must be large. Here, if the group velocity (C _g ) of the A ₀ mode Lamb wave is not constant, the dispersion of the A ₀ mode Lamb wave is generated by the long-range radio wave of the waveguide 30 having a length of 5 m or more. If the phase velocity (C _ph ) cannot be minimized and the width of the magnitude change is not large, the angle switching range of the leaky longitudinal wave radiation beam in the liquid metal (L) cannot be increased. .

For reference, as shown in FIG. 6 and FIG. 7, the waveguide 30 that satisfies the condition that the phase velocity (C _ph ) of the Lamb wave in the A ₀ mode has a large range of magnitude change and the group velocity (C _g ) is constant. Although the thickness (t) is 1.5 mm, the frequency region where the group velocity (C _g ) is constant is in the range of 0.9 MHz to 1.2 MHz. (˜1.7 MHz) is limited.

In order to improve the existing problems as described above, the phase velocity (C _ph ) of the A ₀ mode Lamb wave propagated through the waveguide 30 provided with the coating layer 40 as in the present invention, and the group velocity. Curves of the dispersion characteristics of (C _g ) are shown in FIGS. FIGS. 8 and 9 show that a waveguide 30 formed of SS304 stainless steel plate having a thickness of 1.5 mm and beryllium (Be) on the outer surface of the waveguide 30 formed of SS304 stainless steel plate having a thickness of 1 mm. , The phase velocity (C _ph ) of the A ₀ mode Lamb waves and the group velocity (C _g ) in the waveguide 30 provided with the coating layer 40 formed of aluminum oxide (Al ₂ O ₃ ) and copper (Cu). ) Shows the results of numerical analysis based on theoretical formulas.

For reference, beryllium (Be) and aluminum oxide (Al ₂ O ₃ ) are substances having the highest ultrasonic velocity among various naturally occurring materials, and each longitudinal wave velocity is 12.89 m / ms. And 10.75 m / ms. The longitudinal wave velocity of such beryllium (Be) and aluminum oxide (Al ₂ O ₃ ) corresponds to twice the longitudinal wave velocity of the waveguide 30 formed of SS304 stainless steel plate, 5.79 m / ms. On the other hand, the longitudinal wave velocity of copper (Cu) is 4.66 m / ms, which is slower than the waveguide 30 formed of SS304 stainless steel plate.

Accordingly, if the wave guide 30 is provided with the coating layer 40 formed of beryllium (Be) and aluminum oxide (Al ₂ O ₃ ) having a high ultrasonic velocity on the SS304 stainless steel plate, the phase velocity (C _ph ) and the group velocity are obtained. It can be seen that (C _g ) significantly increases as compared to the waveguide 30 in which the coating layer 40 is not provided, as shown in FIGS. In particular, as shown in FIG. 9, the waveguide 30 including the coating layer 40 formed of beryllium (Be) and aluminum oxide (Al ₂ O ₃ ) has an excitation wave excitation frequency region (0.8 MHz to 1.7 MHz) has a characteristic that the group velocity becomes extremely constant, and the waveform distortion phenomenon due to long-distance radio waves of 5 m or more can be improved. At this time, the phase velocity (C _ph ) and group velocity (C _g ) characteristics of the waveguide 30 provided with the coating layer 40 formed of beryllium (Be) and aluminum oxide (Al ₂ O ₃ ) are similar to each other. I understand that.

When the waveguide 30 is provided with the coating layer 40 formed of copper (Cu) having a low ultrasonic velocity, the phase velocity (C _ph ) is compared with the waveguide 30 without the coating layer 40. And the characteristic that group velocity ( _Cg ) decreases appears. This shows that copper (Cu) is not suitable as a material for the coating layer 40 described in the present invention.

Referring to FIGS. 10 and 11, the phase velocity (C _ph ) of A ₀ mode Lamb waves propagated through the waveguide 30 as the thickness of the coating layer 40 formed of beryllium (Be) increases. It can be seen that the group velocity (C _g ) increases relatively. However, as shown in FIG. 11, when the thickness of the coating layer 40 is 0.5 mm, the phenomenon that the group velocity (C _g ) is kept constant decreases. Accordingly, it is preferable that the thickness of the coating layer 40 coated on the waveguide 30 is approximately 0.125 mm to 0.25 mm for a constant group velocity (C _g ). As shown in FIG. 10, when the thickness of the coating layer 40 is 0.125 mm or more, the phase velocity (C _ph ) of the A ₀ mode Lamb wave is 2 of the longitudinal wave velocity of the lucite wedge 20. It can be seen that it becomes larger than 0.7 m / ms, and it becomes possible to use the wedge 20 formed into a solid that can be used more stably and for a long time even in a high temperature environment.

FIGS. 12 and 13 show curves of dispersion characteristics of the phase velocity (C _ph ) and the group velocity (C _g ) of the waveguide 30 provided with the coating layer 40 in an asymmetric type and a symmetric type. More specifically, in FIG. 12 and FIG. 13, beryllium (Be) is formed only on one side surface of the waveguide 30 formed of SS304 stainless steel plate having a thickness (t) of 1 mm as shown in FIG. 4A. When the asymmetrical coating layer 40 is provided, and as shown in FIG. 4B, beryllium (Be) is formed on both outer surfaces of the waveguide 30 formed of SS304 stainless steel plate having a thickness (t) of 1 mm. Comparison was made with a case where a symmetric coating layer 40 is provided. Here, all the thicknesses of the asymmetric / symmetrical coating layer 40 are 0.125 mm.

As shown in the graphs of FIGS. 12 and 13, the symmetric waveguide 30 having the coating layers 40 on the outer surfaces on both sides is compared with the asymmetric waveguide 30 having the coating layer 40 only on the outer surface on one side. It can be seen that the phase velocity (C _ph ) and the group velocity (C _g ) increase and the group velocity (C _g ) becomes more constant.

For reference, a change in the displacement distribution of the S ₀ mode Lamb wave shown in FIG. 3A appears greatly at the thickness center line (C) of the waveguide 30, and a change in the displacement distribution of the A ₀ mode Lamb wave shown in FIG. to appear larger at the outer surface of the waveguide 30, greatly affected by the surface properties in the case of Lamb waves a ₀ mode. Thus, the effect of increasing the phase velocity (C _ph ) of the A ₀ mode Lamb wave by the coating layer 40 provided on the outer surface of the waveguide 30 is relatively larger than that of the S ₀ mode Lamb wave. On the other hand, as shown in FIG. 13, when it is asymmetric coating layer 40, the effect of group velocity (C _g) is constant appears relatively lower as compared with the coating layer 40 of the symmetric type, A ₀ mode This is because it greatly affects the symmetry of the displacement distribution of Lamb waves.

  FIG. 14 shows that a waveguide 30 formed on an SS304 stainless steel plate having a thickness of 1 mm or 1.5 mm and a waveguide 30 formed on an SS304 stainless steel plate having a thickness of 1 mm are formed of beryllium (Be). A graph representing the radiation angle of leaky longitudinal waves emitted by the waveguide 30 provided with a coating layer 40 of 0.125 mm or 0.25 mm in a liquid metal (L) containing sodium is shown.

The radiation angle (α) of the leaking longitudinal wave is derived by α (f) = sin ⁻¹ [V _L / C _ph (f)] according to Equation 1. When the thickness (t) of the waveguide 30 is 1 mm in the excitation frequency region (0.8 MHz to 1.7 MHz) of the incident wave, a leakage longitudinal wave is generated in a limited manner, and the thickness of the waveguide 30 ( When t) is 1.5 mm, it can be seen that there is a problem in that the beam radiation angle changes rapidly in the low frequency region of 1 MHz or less and the beam divergence angle of the radiation beam increases. However, it can be seen that by providing the waveguide 30 with the coating layer 40, the switching range of the beam radiation angle of the leakage longitudinal wave becomes constant.

  As described above, the preferred embodiments of the present invention have been described with reference to the preferred embodiments of the present invention. However, those skilled in the relevant technical field will not depart from the spirit and scope of the present invention described in the claims. Thus, it will be understood that the present invention can be variously modified and changed. That is, the technical scope of the present invention is defined based on the claims, and is not limited by the best mode for carrying out the invention.

1: Wave guide ultrasonic sensor device 10: Ultrasonic sensor 20: Wedge 30: Wave guide 40: Coating layer 50: High power ultrasonic system

Claims (8)

An ultrasonic sensor that transmits and receives an ultrasonic signal to and from the object;
A wedge that supports one side of the ultrasonic sensor and switches a mode of the ultrasonic signal;
A wave guide provided between the wedge and the object, for guiding the transmitted and received ultrasonic signals;
A high-power ultrasound system for processing the transmitted and received ultrasound signals;
Including
A waveguide ultrasonic sensor device, wherein a coating layer formed of aluminum oxide (Al ₂ O ₃ ) and / or beryllium (Be) is provided on at least a part of an outer surface of the waveguide.   The coating layer is provided symmetrically on one side and the other side across the waveguide, or is provided asymmetrically only on one side or the other side of the waveguide. The waveguide ultrasonic sensor device according to claim 1.   The waveguide ultrasonic sensor device according to claim 2, wherein the coating layer has a thickness of 0.125 mm to 0.25 mm.   The waveguide ultrasonic sensor device according to claim 2, wherein the waveguide is formed on a stainless steel plate, has a length of 5 m or more, and a thickness of 1 mm to 2 mm.   The waveguide ultrasonic sensor device according to claim 1, wherein the wedge is formed as a solid. A wave guide ultrasonic sensor device for visualizing an ultrasonic signal of a state of an object placed in a high temperature, high radioactivity and / or opaque extreme environment,
Aluminum oxide (Al ₂ O) provided between an ultrasonic sensor that transmits and receives the ultrasonic signal and an object, increases the phase velocity on the outer surface of the waveguide that guides the ultrasonic signal, and maintains the group velocity constant. ₃ ) A waveguide ultrasonic sensor device provided with a coating layer formed of beryllium (Be) and / or beryllium (Be).   The waveguide is provided in a plate shape, and the coating layer is provided asymmetrically or symmetrically on the outer surface of one side or both sides of the waveguide, or in at least a partial region of the outer surface of the waveguide. The waveguide ultrasonic sensor device according to claim 6, wherein the waveguide ultrasonic sensor device is formed. The waveguide ultrasonic sensor device according to claim 6, wherein the coating layer has a thickness of 0.125 mm to 0.25 mm.

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