JP2971098B2 - Coupling medium for ultrasonic testing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for efficiently transmitting ultrasonic waves transmitted from a probe into a test body when performing an ultrasonic flaw detection test. The present invention relates to a couplant for an ultrasonic flaw detection test which is applied between probes.

[Prior Art] Conventionally, glycerin, oil, water, and the like have been mainly used as a couplant for an ultrasonic flaw detection test applied between a test piece and a probe when performing an ultrasonic flaw detection test. .

[Problems to be Solved by the Invention] There is no problem when these couplants are used at room temperature, but when these couplants are used at high temperatures, organic substances are unstable at high temperatures. Decomposition may cause deterioration, gas may be generated, and boiling may occur, and transmission of ultrasonic waves may be significantly impaired. Generally, nucleate boiling (cavitation) occurs due to the action of ultrasonic waves, so that even at a temperature lower than the boiling point, ultrasonic transmission is significantly inhibited.

On the other hand, various couplants for use at high temperatures have been announced, but many of them have smoked at high temperatures, have significantly deteriorated stability, and transmission loss has rapidly deteriorated with time. As a result, it was not possible to find a couplant which could be used stably at a temperature exceeding 300 ° C. for a long time.

Further, since the liquid does not have a shearing force, flaw detection is performed using honey or the like having extremely high viscosity as a couplant which propagates a shear wave (shear wave). However, when it is necessary to move the probe and perform flaw detection (scanning) in order to use an extremely viscous material, there is a problem that it becomes difficult to move the probe smoothly, and after the flaw detection, There was a problem that removal of the couplant was not easy.

An object of the present invention is to provide a couplant for an ultrasonic flaw detection test that can be used stably for a long time even at a high temperature, can easily propagate a transverse wave, and can smoothly scan a probe. It is intended for.

[Means for Solving the Problems] The couplant for ultrasonic testing according to the present invention has a P ₂ O ₅ of 20 to 69.
Wt.%, M ₂ O (M is an alkali metal) is a couplant consisting of a composition containing 20 to 38 wt.
The couplant is characterized in that it melts in a temperature range from room temperature to 650 ° C., changes in viscosity, and has a property of semi-liquefaction or liquefaction.

Further, the composition is characterized in that B ₂ O ₃ contains 60% by weight or less, SiO ₂ contains 40% by weight or less, and Al ₂ O ₃ contains 40% by weight or less.

Further, the couplant may be dissolved or suspended in water or an organic solvent in a water-soluble or semi-water-soluble one,
It can be solidified by dissolving in water or an organic solvent and leaving, or by heating and dissolving and leaving.

[Operation] By applying the couplant for ultrasonic testing of the present invention between the test piece and the probe, a stable ultrasonic testing can be performed even at a high temperature exceeding 300 ° C.

[Examples] Examples of the present invention will be described below.

Glass powders shown in Table 1 below were prepared and tested as couplants for ultrasonic testing.

Table 1 shows sample symbols and compositions, and FIG. 3 shows a change in viscosity of each sample with respect to a change in temperature.

In the present invention, an inorganic glass is used, and the glass is melted by a rise in temperature and the viscosity gradually changes.
FIG. 3 shows an example of the change in viscosity at high temperature of various glasses within the composition range of the present invention. In addition, glass
Since it is stable at high temperatures for a long time, it can be used as a couplant for propagating ultrasonic waves to a test body stably even when used for a long time. Further, it is clear from FIG. 3, for example, that it is possible to obtain an optimum viscosity for transmission of ultrasonic waves by selecting a composition having an appropriate composition for the operating temperature.

That is, in accordance with the temperature of the place where the ultrasonic inspection test is performed, the glass powder is melted at that temperature, and a glass powder having a composition within a range where an appropriate viscosity is obtained is selected from, for example, FIG. , And can be flawed using a probe that can be used at a high temperature after being melted. Also,
Depending on the composition, it can be melted without crystallization in water. For example, taking the example of the symbol F in Table 2 described below as an example, as shown in FIG. 5, from a solution containing 25% of water, a glassy state is maintained without crystallization as the temperature rises. As shown in FIG. 4, a change in viscosity occurs.
As a result, the water content is also reduced (see FIG. 5), and the operation of the probe can be performed stably and smoothly. Thus, it can be used as a couplant in a wide temperature range from normal temperature to high temperature.

In the test for using each glass powder as a couplant, as shown in FIG. 1, a piezoelectric element 1 and 2 for transmitting and receiving ultrasonic waves were attached by brazing 3 and a split type in which heat resistance was remarkably improved. The thickness of the test piece 6 was measured using the probes 4 and 5 described above. For the measurement, a steel plate having a thickness of 10 mm was used for the test piece 6, and the couplant 7 shown in Table 1 was placed between the test piece 6 and the probes 4 and 5.
Was applied, the test piece 6 was heated to each temperature by the heater 8, and the plate thickness was measured at each temperature using a couplant. At this time, the waveform shown in FIG. 2 is obtained on the cathode ray tube of the flaw detector. The vertical axis indicates the sound pressure of the obtained echo, and the horizontal axis measures the time until the ultrasonic wave transmitted by the piezoelectric element 1 is received by the piezoelectric element 2 again.

The echo indicated by S in FIG. 2 shows an echo at the interface between the probes 4 and 5 and the test piece 6 (II ′ in FIG. 1), and B ₁ denotes the back surface of the test piece 6 (first The echo at II-II ') in the figure is shown. Further, B ₂ is obtained by the rear surface (II-II of Figure 1 ') ultrasonic waves reflected by the surface (II of Figure 1 of the specimen 6' further reflected by), reflected by the back surface again This is the echo that was received. Therefore, the time difference on the horizontal axis at which the S wave and the B ₁ wave or the B ₁ wave and the B ₂ wave were obtained; from t ₁ and t ₂ , the sound velocity at the temperature at each measurement obtained in advance was obtained. The thickness of the plate can be measured.

According to the test results, it was known that any of the produced glass powders had sufficient performance as a couplant. That is, the glass powder A had an appropriate viscosity at 570 ° C., the glass powders B and C had an appropriate viscosity at 650 ° C., and the glass powder D had an appropriate viscosity at 350 ° C., and good thickness measurement was possible. In addition, the glass powder E was also tested up to 500 ° C. in this test, and in the temperature range, good results were obtained.

That is, according to the measurement using the present couplant, it is possible to stably measure the thinning due to corrosion and abrasion occurring during operation of the structure even at a high temperature during operation. It can also be understood that if glass powder having a composition having an appropriate viscosity is properly used at the time of measurement depending on the temperature of the structure, more stable and accurate measurement is possible.

The high-temperature probe used had a brazing temperature of 600
When the temperature reaches around ℃, the heat resistance is impaired.However, in this test, a steel delay material was attached between the test piece and the piezoelectric element. The measurement was completed before it was transmitted to the attachment part and reached around 600 ° C, and it was possible to measure even when the temperature of the specimen was 650 ° C.

When glass powder is used, it is solid near normal temperature, and ultrasonic waves cannot be transmitted from the probe to the specimen. Ultrasonic waves are transmitted into the specimen only when the temperature becomes high and the glass powder becomes viscous and becomes liquid.

On the other hand, in order to continuously transmit ultrasonic waves from a normal temperature to a high temperature into a test piece, the use of glass powder suspended in water or an organic solvent was studied. The test was performed using the symbol E shown in Table 1 and the glass powder F shown in Table 2.

The test was performed by measuring the plate thickness in the same manner as when the glass powder was used as it was. In this test, glass powder was dissolved in water at room temperature. The ratio of the added water was about 1/4. The results of the test are shown in FIG. The vertical axis represents a relative sensitivity or the like of the first bottom echo height (B ₁ echo height of the second panel), the horizontal axis represents the test temperature. The first bottom echo height may be considered to depend on the ease of transmission of ultrasonic waves in the couplant. The bottom echo height was clearly discernable in all ranges from room temperature to high temperature, and the plate thickness could be measured.

In FIG. 6, the dotted line also shows the measurement results when the same measurement was performed using various commercially available high-temperature couplants. Among the used ones, the operating temperature range is 600 ℃
According to the results of the same tests as the developed couplant, the usable temperature of the commercially available couplant was considered to be at most around 300 ° C. In addition, it can be seen that the one using the developed glass powder is superior to the commercially available one, and that there is a clear difference between the two especially in the temperature region exceeding 300 ° C.

In this test, glass powder was dissolved in water and used.However, semi-water-soluble glass powder was suspended in water, and the surface of the powder was melted and the connection between particles occurred. However, it can transmit ultrasonic waves and can be used as a high-temperature couplant.

In addition, if the suspension obtained by suspending glass powder in water is put into a tube or the like and stored for a long period of time, the viscosity gradually increases and may gradually solidify. In some cases, it is difficult to remove the couplant from the material, which may significantly impair workability. For this reason, storage is facilitated by solidifying in advance and shaping the shape into thin pieces so that the shape is easy to use. That is, when a previously shaped flake is placed on a high-temperature specimen and heated, liquefaction occurs, and the flake can be easily used as a couplant. As a result, a couplant which is excellent in storage and further excellent in workability can be supplied.

Furthermore, suspensions containing glass powder allow the propagation of shear waves and can also be used as couplants for shear waves.

The glass powder has a suitable viscosity according to the temperature as the temperature becomes high from the state containing water and loses water. Therefore, when the glass powder is used as a couplant, the probe can move extremely smoothly (scan). It is clear that this is possible. In particular, the conventional shear wave couplant has a very high viscosity,
Although the scanning of the probe was difficult, the scanning was extremely easy with the present invention.

In addition, not only water but also a suspension in an appropriate organic solvent or the like can be used.

Further, the glass powder can be used as a high-temperature couplant as long as the composition is as described in claim 1 without using the glass powder suspended in water or an organic solvent. The result indicated by the dashed line in FIG. 6 is the result of using the same composition as that of F in Table 2, but using the powder of each component uniformly mixed and then suspended in water. Yes, the powder is not vitrified. Compared to the solution of vitrified material in water, the measurement sensitivity in the temperature range over 150 ° C was worse, and although it reached a minimum at around 300 ° C,
It can be seen that it can be sufficiently used as a couplant even at a temperature of not less than 0 ° C., and has an excellent measuring ability as compared with a commercially available couplant for high temperature. That is, the composition range described in claim 1 of the present invention is a claim, and does not necessarily assume that the composition is vitrified. However, the use of a vitrified material in advance can provide more stable and superior characteristics.

If the glass powder is dissolved in water and the paste is left as it is, the glass powder gradually loses its viscosity and solidifies.
This tendency was remarkable especially when it was melted in the warm summer months and cold in the winter months. It has excellent workability when the melted material is used immediately, but when it is stored in a tube for a long period of time, for example, a problem that it hardens in the tube occurs, which significantly impairs the workability.

In order to facilitate workability and storage of the couplant, it is conceivable that the solidified in advance is processed into a thin slice for easy use, and this is attached to a high-temperature structure for measurement. . The results indicated by the double line in FIG. 6 were obtained by dissolving a glass powder having the composition of F in Table 2 in hot water at about 50 ° C., and then leaving it at room temperature to make a test. The results are shown.

At a sensitivity of about 200 ° C or less, the thickness can be measured, although the glass powder is slightly inferior to that of a glass powder suspended in water. Thus, the results are comparable to those obtained by using a solution dissolved in liposome, and provide a couplant excellent in storage and workability.

If a glass powder is used, some bubbles are generated at a high temperature. However, even in this case, the measurement can be performed without any problem only by slightly applying pressure to the probe from above, as shown in the measurement results in FIG. 6, but in order to reduce the amount of generated bubbles, Naturally, it is also conceivable to remove bubbles by heating in a reduced pressure beforehand.

Further, when the glass powder is used at a high temperature exceeding, for example, 500 ° C., some components may show slight corrosiveness, but for the purpose of reducing this corrosiveness, an organic component may be added and stabilized. Of course, this is predictable and is within the scope of the claims.

Also, the scope of the present invention includes a case where the couplant of the present invention is used for acoustic emission in which an AE sensor having the exact same structure is attached to a structure and ultrasonic waves generated by the structure are received.

Next, a test was performed as a couplant for propagating a transverse wave. A shear wave, which is a shear wave, does not propagate in a liquid having no shear force. For this reason, even if these liquids are used as a couplant, ultrasonic waves cannot be transmitted. For this reason, an extremely viscous liquid such as honey is used as a couplant. However, when these are used, the scanning of the probe becomes extremely poor, and the workability becomes extremely poor.

Using the properties of amorphous glass, we investigated its use as a couplant for shear waves. The test was carried out using the glass powder of E in Table 1 and a plate thickness of 10 using a vertical probe for shear wave.
The characteristics of the couplant were studied by comparing the echo height of the first bottom surface of a steel plate of mm. The results are shown in FIG. The horizontal axis shows the concentration of the glass powder when the glass powder is dissolved in water.
The relative sensitivity on the vertical axis is shown in comparison with the sensitivity when a commercially available shear wave couplant is used. It can be seen that the higher the concentration of the glass powder, the higher the sensitivity, and that it exhibits superior ultrasonic transmission properties than commercially available ones. In addition, the developed couplant was known to be a very high performance couplant having excellent probe scanability and excellent workability.

In addition, although the test regarding the measurement of the plate thickness was performed here,
It is clear that the generated couplant can also be used effectively for detecting defects in the material at a high temperature by using a vertical probe or an oblique probe.

[Effects of the Invention] Conventionally, when detecting the thickness or defect of a specimen exceeding 300 ° C., the measurement was not possible due to fumes and vaporization or solidification of the couplant. If a medium is used, stable measurement can be performed even at a high temperature exceeding 300 ° C.

Further, the conventional couplant for propagating the shear wave has poor workability in scanning the probe, but the present invention can be used as a couplant for the shear wave having excellent workability.

By adjusting the composition of the couplant of the powder to a composition suitable for the purpose of measurement, it is possible to apply the powder to the test object and obtain a suitable viscosity at each measurement temperature to perform stable measurement. it can. Further, in order to enable continuous measurement from room temperature, the powder of the present invention is suspended in water or an organic solvent and used, thereby enabling stable ultrasonic inspection from room temperature to high temperature. Furthermore, by solidifying the couplant with excellent preservability and shaping it into a flake shape in advance, it can be used as a couplant with excellent workability.

Therefore, it was possible to perform ultrasonic inspection performed by scanning the probe using a couplant at a temperature exceeding 300 ° C., which was difficult in the past.

Conventionally, it has been difficult to operate a probe for a couplant that propagates a transverse wave, but a couplant having excellent scanning properties can be obtained by utilizing the properties of amorphous glass.

[Brief description of the drawings]

FIG. 1 is a side view showing a state in which an ultrasonic flaw detection test is being performed, FIG. 2 is a waveform diagram appearing on a CRT at the time of the test, and FIGS. FIG. 5 is a graph showing the relationship between the temperature and the water content of the couplant, FIG. 6 is a graph showing the relationship between the test temperature and the relative echo height, and FIG. 7 is the concentration of the glass powder and the relative echo. It is a graph which shows the relationship with height. In the figure, reference numerals 1 and 2 denote piezoelectric elements, 4 and 5 probes, 6 a test body, 7 a couplant, and 8 a heater.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor, Yoshimichi Atsuta 1-9-4, Fukuura, Kanazawa-ku, Yokohama-shi, Kanagawa Pref. 1-8-8 Kagaoka (72) Inventor Joji Ota 1-680-24 Satsukidai, Ikoma-gun, Nara Prefecture (56) References JP-A-2-115764 (JP, A) JP-A-61-105459 (JP, A) JP-A-60-82854 (JP, A) JP-A-56-119851 (JP, A) Kaisho 60-36952 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G01N 29/00-29/28

Claims (4)

(57) [Claims] 1. A couplant comprising a composition comprising 20 to 69% by weight of P ₂ O _{5 and} 20 to 38% by weight of M ₂ O (M is an alkali metal). A couplant for an ultrasonic flaw detection test, characterized in that it has the property of melting in the temperature range from room temperature to 650 ° C., changing its viscosity and becoming semi-liquefied or liquefied. 2. The ultrasonic flaw detection method according to claim 1, wherein the composition contains 60% by weight or less of B ₂ O ₃ , 40% by weight or less of SiO _{2 and} 40% by weight or less of Al ₂ O _3. Test couplant. 3. The couplant for an ultrasonic flaw detection test according to claim 1, wherein the couplant is dissolved or suspended in water or an organic solvent. 4. The couplant for an ultrasonic flaw detection test according to claim 1, wherein the couplant is solidified by being dissolved in water or an organic solvent and allowed to stand, or by being dissolved by heating and allowed to stand.