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DESCRIPTION JPH01162181

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DESCRIPTION JPH01162181
[0001]
[Industrial application field] This invention is intended to recognize the position and shape of a
structure and various devices in the reactor in a high temperature ultrasonic transducer, in
particular, a reactor vessel filled with liquid sodium which is an opaque substance. Related to
PRIOR ART FIG. 2 is a cross sectional view showing a conventional high temperature ultrasonic
transducer. In the figure, (1) is a cylindrical planar stainless steel case, (2) is a stainless steel case
cover for sealing the opening of the stainless steel case (1), and is assembled by welding to the
stainless steel case (1). Is configured. (3) is a disk-shaped high-temperature ultrasonic transducer
made of lithium niobate disposed on the inner surface of the bottom of a stainless steel case (1),
having a Curie point of 1200 ° C., and an electromechanical coupling coefficient Kt (Kt-Dt 1),
the frequency is 2.5 MIIz, and the pulse width is about 50 μsec. (4) is a silver paste which is a
bonding member fired at 800 ° C., and the high temperature ultrasonic transducer (3) is bonded
to the inner surface of the bottom of the stainless steel case (1). (5) is a hermetic seal connector
attached through the stainless steel case cover (2), (6) is a wire covered with a silicone rubber
tube, and the seal connector (5) and the ultrasonic transducer for high temperature ( 3) are
connected. (7) is an MI cable (Mineral Insulated Cable) connected to the seal connector (10), and
(8) is a post attached to the stainless steel case force / <− (2). A conventional high-temperature
ultrasonic transducer is configured as described above, and a sealed container incorporating a
high-temperature ultrasonic transducer (3) consisting of lithium niobate having a Curie point of
1200 ° C. has a stainless steel case (1) and a stainless steel case Since it consists of a cover (2),
it has corrosion resistance and is used for a long time even in a reactor vessel with a temperature
of 200 ° C to 250 ° C and radiation of 1.0 x 10 BRad order. Can. Also, when a predetermined
voltage is applied to the ultrasonic transducer (3) sealed by the stainless steel case (1) and the
stainless steel case cover (2), an ultrasonic wave with a pulse width of 50 μsec and a frequency
of 2.5 MHz The ultrasonic wave passes through the bottom of the stainless steel case (1) and is
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sent out of the stainless steel case (2). At this time, the directivity angle was 1.3 ° (-6 dB) and
the S / N ratio was at most 20 dB.
[Problems to be solved by the invention] In the conventional high temperature ultrasonic
transducer as described above, the high temperature ultrasonic transducer (3) has a Curie point
of 1200 ° C. and an electromechanical coupling coefficient of 0, 17 niobate It is excellent in
moisture resistance because it is made of lithium, but it has a small electromechanical coupling
coefficient, poor conversion efficiency between electricity and ultrasonic waves, and a low S / N
ratio due to small ultrasonic energy. was there. In addition, lithium niobate has a problem of
intergranularity (i.e., it is easily cracked (also weak to thermal shock, and furthermore, the
production yield at the time of ultrasonic transducer production is poor). The present invention
has been made to solve such problems, and its object is to obtain a high-temperature ultrasonic
transducer having a good S / N ratio and a good production yield at the time of ultrasonic
transducer manufacture. [Means for Solving the Problems] The high-temperature ultrasonic
transducer according to the present invention is a high-temperature ultrasonic transducer having
a Curie point of 300 ° C. or higher and made of lead titanate ceramic on the inner surface of the
bottom of a container made of stainless steel. The vibrator is attached by a bonding material.
[Operation] In the present invention, since the high-temperature ultrasonic transducer is formed
of a lead titanate-based ceramic having a Curie point of 300 ° C. or higher, the
electromechanical coupling coefficient is larger than that of lithium niobate. The conversion
efficiency between electricity and ultrasonic waves is good, there is no space between them and
there is no resistance to thermal shock, and the manufacturing yield at the time of manufacturing
ultrasonic vibrators is also good. FIG. 1 is a cross sectional view showing an embodiment of the
present invention. In the figure, the same components as those of the conventional example are
denoted by the same reference numerals, and the description of the duplicated components is
omitted. (13) is a disk-shaped high-temperature ultrasonic transducer made of lead titanatebased ceramic, having a Curie point of 360 ° C., an electromechanical coupling coefficient of
0.45, a frequency of about 2.5 MHz, and a pulse width of 20 μSee belongs to. The present
invention is the same as the conventional example except for the structure of the hightemperature ultrasonic transducer (13). In the high-temperature ultrasonic transducer configured
as described above, the high-temperature ultrasonic transducer (15) made of lead titanate-based
ceramic has a Curie point of 360 ° C., and the use condition of the transducer is 200 ° C. to
250 ° C. Since the temperature is 0 ° C., the electromechanical coupling coefficient of the
conventional high-temperature ultrasonic transducer (3) which operates normally with an
electromechanical coupling coefficient of 0.45 and a conventional lithium niobate (3) without
influence of temperature is 0. Compared to 17, the conversion efficiency between electricity and
ultrasonic waves is good, and the S / N ratio is improved.
Moreover, since lead titanate ceramics are polycrystalline, they do not break apart, so they are
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hard to break and resistant to thermal shock. Therefore, the manufacturing yield at the time of
ultrasonic transducer manufacture became favorable, and the life was also improved. [Effects of
the Invention] As described above, the high temperature ultrasonic transducer attached with the
bonding material to the inner surface of the bottom of the container made of stainless steel is a
lead titanate-based ceramic having a Curie point of 300 ° C. or higher. Since the range of the
piezoelectric phenomenon spreads to the high temperature side, stable ultrasonic waves can be
generated even at high temperature, the electromechanical coupling coefficient is large, there is
no male openness, and the thermal shock is strong. The mutual conversion efficiency is
improved, the S / N ratio is improved as compared with the conventional one, and the production
yield at the time of ultrasonic transducer manufacture and the life are also improved.
[0002]
Brief description of the drawings
[0003]
FIG. 1 is a cross-sectional view showing an embodiment of the present invention, and FIG. 2 is a
cross-sectional view showing a conventional high-temperature ultrasonic transducer.
In the figure, (1) is a stainless steel case (container), (2) is a stainless steel case cover (container),
(4) is a silver paste (joining member), and (13) is an ultrasonic transducer for high temperature.
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