JP2009150692A - Method for inspecting sprayed coating and equipment for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for inspecting a sprayed coating enabling to check the stripping of the sprayed coating through nondestructive inspection by means of ultrasonic waves, in particular, without any contamination due to a liquid medium for ultrasonic waves; and to provide equipment for the method. <P>SOLUTION: In the equipment for inspecting the sprayed coating, a transmitting part and a receiving part respectively comprise a probe 1 and 2 for airborne ultrasonic waves. Both probes 1 and 2 are arranged above the sprayed coating. The probe 1 of the transmitting part faces obliquely to the sprayed coating. Distance between the probe 1 of the transmitting part and the probe 2 of the receiving part is not less than 4 times the thickness of the sprayed coating. The probe 1 of the transmitting part emits ultrasonic waves towards the sprayed coating beneath it and let the ultrasonic waves go into the sprayed coating, the probe 2 of the receiving part receives surface waves coming into the air, and thereby the stripping at the interface is detected from intensities of the received ultrasonic waves. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a thermal spray coating inspection method and apparatus.

Japanese Patent No. 3037627 JP-A-6-331609 Japanese Patent No. 3956486

By forming a thermal spray coating, the surface of an existing structure such as a tank or an industrial machine can be coated to improve life, improve performance, and reduce production / maintenance costs (Patent Document 1). ).
When forming such a sprayed coating, it is necessary to clean and roughen the substrate by blasting before spraying, or to seal the holes present in the formed sprayed coating after spraying.・ Indispensable treatment for thermal spraying for rust prevention.
However, at present, a method for nondestructively examining such pretreatment and the superiority or inferiority of the sealing treatment after thermal spraying on the spot has not been established.
That is, in order to ensure good adhesion between the substrate and the thermal spray coating, a clean rough surface is required. However, contamination of the blasting material, contamination by scattered oil or dust after blasting, etc. It is very difficult to avoid completely. On the other hand, since the process fluid may penetrate into the substrate interface during operation and damage may occur, it is important to quickly inspect the interface properties after thermal spraying or during regular maintenance.
In addition, it is extremely important to ensure that the sealant penetrates the entire surface uniformly in order to ensure the anticorrosion performance, but there is no established method for nondestructive examination of this point as well. .

  Specifically, as the method for inspecting and measuring the above-mentioned interface property (adhesion strength), a peeling method or a scratching method is used as a method for measuring the adhesion strength of the sprayed layer. There are problems such as being a typical evaluation method and a small-area laboratory evaluation method using a special apparatus. In the method of peeling off the sprayed layer using an adhesive, there is a problem that the adhesive may permeate into the sprayed layer, and there is a problem that it cannot be applied to a sprayed layer having an adhesion strength stronger than that of the adhesive. In particular, as described above, these test methods are destructive tests and cannot be used for products.

As a method for examining the degree of sealing, there is a ferroxyl method.
However, this method can be applied only to a non-ferrous metal or ceramic sprayed film, and cannot be applied to an alloy sprayed film containing an iron component.
Further, there is a method of cutting the sprayed layer and examining the cross section with a metal microscope or an electron microscope, but it is not easy to check whether or not the sealing agent has penetrated into the pores and sealed. Since this method is a destructive test, it cannot be used for products.
Electrochemical test methods such as measuring polarization curves and corrosion potentials cannot be applied to large areas even if they can be applied to small areas, and they cannot be applied to products because they damage the sprayed layer.
There is a method of measuring the surface wave excited by a pulsed laser with a laser interferometer and evaluating the film quality from the velocity dispersion (past research by Takemoto et al.). However, an expensive laser device is required, like a sprayed film. Application to rough surfaces is limited. In addition, in the inspection method using a contact ultrasonic sensor (pulse echo method or surface acoustic wave method), the surface of the sprayed layer is rough, so that ultrasonic waves cannot be input efficiently, and the influence of the rough surface is significant. Because it requires a special co-plant agent, it cannot be used in products.

  Thus, it is important to inspect whether peeling occurs between the thermal spray coating and the base material, or between the thermal spray layers constituting the thermal spray coating, as described above, However, at present, no inspection method has been established by nondestructive inspection.

On the other hand, as a nondestructive inspection in other fields for detecting internal defects in railway axles and aircraft materials, an ultrasonic flaw detection method is known in which ultrasonic waves are incident on a material to be detected to detect defect echoes.
In view of the above points, the inventor of the present application has examined whether there is a method that can easily inspect the presence or absence of the thermal spray coating by using such an ultrasonic flaw detection method as a nondestructive inspection method.
In normal ultrasonic flaw detection, an ultrasonic medium such as water or oil that propagates ultrasonic waves is required between the probe and the test material in order for the ultrasonic wave to enter the test material. .
Such a media solution causes contamination of the sprayed coating. In addition, for plant equipment that has undergone thermal spraying, it is necessary to have a large-scale inspection device in order to examine the peeling of the thermal spray coating by using an ultrasonic flaw detection method using a mediator solution. However, it is not possible to carry out inspection simply.

Therefore, the inventor of the present application paid attention to a technique called aerial ultrasound that does not use the above-described medium solution (Patent Document 2).
For example, as seen in Patent Document 2, this technique of aerial ultrasonic waves propagates ultrasonic waves into the air and receives ultrasonic waves reflected by the objects in the air. It is used to measure the position and distance to an object.
In general, when dissimilar media that propagate ultrasonic waves are in contact with each other, if there is a large difference in acoustic impedance (sonic wave velocity × medium density) between the media, the ultrasonic waves propagated in one medium It is known that it is difficult to propagate to a medium.
As described above, the conventional ultrasonic flaw detection method for examining internal defects in steel materials is to propagate ultrasonic waves into the ultrasonic medium between the probe and the test material so that the ultrasonic waves enter the test material. Yes, solid piezoelectric elements have a large acoustic impedance, and gas air has a small acoustic impedance and the difference between them is large. Therefore, the conventional probe is used as it is for aerial ultrasound transmission. It cannot be used as a probe for a part (transducer) or a receiver (receiver), and a dedicated probe is used when using aerial ultrasonic waves.

As such an aerial ultrasonic probe, the following four types are known.
One of them is the one in which the difference in acoustic impedance is relatively small for both the piezoelectric element made of zircon and lead titanate and the air, and clay (clay) is provided on the surface of the piezoelectric element (U.S. Ultran). Company-made).
The other is a sensor called a composite, which is called a composite piezoelectric transducer, in which a part of the piezoelectric element is replaced with a resin having low acoustic impedance. This resin is generally called a 1-3 type composite material. In addition, as such a resin, epoxy is mainly used in the United States, and a composite material using polyurethane is mainly used in Japan (sales of Research Laboratory, Inc.).
The other is to use a capacitor (insulating resin or air layer), and it is necessary to apply a bias voltage to electrodes sandwiching the capacitor (developed by Warbic University, UK).
Still another one uses a polymer piezoelectric film (PVDF / polyvinylidene fluoride), and is called an ultrasonic microscope, which is a method of inspecting a material surface with high-frequency ultrasonic waves using water as a medium. It is used for transmission / reception sensors.

  By using the above probe, it has become possible to propagate ultrasonic waves into the air using air ultrasonic waves. For example, ultrasonic waves are incident on a solid steel material as in the past. The use of this method for examining internal defects was out of the question. As described above, although it is possible to propagate ultrasonic waves in the air, it is difficult to make ultrasonic waves enter the steel material propagated in the air due to the difference between the acoustic impedance of the air and the acoustic impedance of the steel material. As described above, it was used as a position sensor or a distance measurement sensor that can be realized exclusively by propagation of ultrasonic waves in the air.

As a result of research, the present inventor has found that a sprayed powder material is sprayed onto the surface of a substrate at a high temperature, and ultrasonic waves can be incident on the formed metal or ceramic sprayed coating by airborne ultrasonic waves.
The reason that aerial ultrasonic waves can be incident on the thermal spray coating in this way is thought to be because the mechanism for propagating the ultrasonic waves after incident on the thermal spray coating is different from the uniform solid material inside. It is done.
Specifically, the thermal spray coating is generally formed by spraying a thermal spray material melted at a high temperature toward a base material to be coated in the air, and while spraying in the air by the spray, The material is cooled to be in the form of fine flakes, and becomes a thermal spray coating by sequentially overlapping and solidifying on the substrate surface. For this reason, the formed sprayed coating does not form a uniform film microscopically. That is, a plurality of flake-like agglomerates are partly integrated by melting and the material is uniform, but the other part still remains in the form of scaly agglomerates. It is considered that the ultrasonic wave propagates along the boundary between such adjacent agglomerates.
Therefore, by such a mechanism, as described above, air ultrasonic waves can be incident on the sprayed coating.

  On the other hand, in ultrasonic inspection of internal defects in steel materials using the above-described conventional medium, the probe of the receiver (receiver) is tested against the probe of the transmitter (transducer). Place on the same side with respect to the test material, the transmission method to arrange the opposite side across the material, and to examine the ultrasonic wave transmitted through the test material, both the transmitter and the receiver There is a reflection method in which an ultrasonic wave is incident on a test material and an internal defect is detected by detecting a reflected wave (echo) reflected from the test material.

When applying such conventional flaw detection technology to peeling inspection by air ultrasonic waves, in large plant equipment such as a tank with a sprayed coating, the transducer and receiver are opposed to each other with the test material in between. It is difficult to arrange them on the side, and flaw detection by the above transmission method is not realistic at the installation site.
For this reason, the inventor of the present application arranges the transducer and the receiver on the surface side of the thermal spray coating, including the case of using a probe for both transmitting and receiving, and reflects the reflected ultrasonic wave incident on the thermal spray coating on the incident side. The examination by the reflection method described above was examined.
However, in the thermal sprayed coating having a thickness of 1 mm or less, the range to be examined is narrow, and the ultrasonic wave directly reflected from the inspection portion, that is, the interface between the substrate and the thermal sprayed coating or the interface between the layers in the thermal sprayed coating ( Echo) is received, and when the state of the interface is examined from the reflected wave, the reflected wave from the interface is discriminated by being hidden by noise (reflected noise) such as a reflected wave generated at the incident position on the surface of the thermal spray coating. Was extremely difficult. In particular, as described above, in the thermal spray coating composed of agglomerates, not only the reflected wave at the incident position on the surface of the thermal spray coating but also multiple reflections between the agglomerates near the incident position on the surface due to the reflected wave are remarkable. Therefore, the decay time of noise is relatively long, making it difficult to detect the reflected wave from the interface.
As shown in the cited document 3, the receiving probe of the AE apparatus is placed on the sound part of the sprayed coating formed on the surface of the structure, and the ultrasonic oscillator is sent over the inspection portion of the sprayed coating. The receiving probe is arranged in such a manner that the thermal spraying at the inspection position is vibrated by the operation of the ultrasonic oscillator by sequentially contacting the credit probe and the vibration propagating through the structure is arranged on the healthy part of the thermal spraying coating. The vibration waveform is displayed on the display after being received by the AE device via the child, and the frequency of the waveform is subjected to an FFT calculation, and from the position of the peak frequency region of the waveform after the FFT calculation, A spray coating peeling detection method on the surface of a structure that distinguishes between a healthy portion and detects a peeling portion has been proposed, but this generates surface waves that enter the thermal spray coating and propagate in the coating. By using the surface wave with directionality Detection of the presence or absence of delamination by performing FFT operation inspection on the frequency of the vibration waveform by directly vibrating both the film and the substrate by contacting the piezoelectric element with an AE device. In reality, it is difficult to detect peeling with high accuracy.
In addition, in Patent Document 3, the influence on the film due to vibration is not taken into consideration, and it may be used for a film baked at a high temperature. It is difficult to implement.

  The present invention makes it possible to inspect the presence or absence of thermal spray coating peeling using airborne ultrasonic waves. In addition, the present invention solves the above-mentioned noise problem and makes it possible to accurately detect the presence or absence of peeling of the sprayed coating installed at a site such as plant equipment using airborne ultrasonic waves. Furthermore, the present invention makes it possible to inspect the sealing suitability using airborne ultrasonic waves.

The inventor of the present application, when the ultrasonic wave traveling between the agglomerates reaches the interface between the sprayed layers or the interface between the sprayed layer and the base material, macroscopically generates a surface wave that propagates along the interface. We considered that the presence or absence of delamination can be detected by investigating the strength of surface waves leaking from the surface of the thermal spray coating into the air after propagating along such an interface. Further, it was considered that by receiving a surface wave leaking out from the above-mentioned noise, it can be reliably detected without being disturbed by the above-mentioned noise.
Then, when the surface waves that leaked out were examined, if the above-mentioned interface was in close contact, the incident ultrasonic waves entered the substrate and the lower layer, so the intensity of the ultrasonic waves that leaked into the air was strong. If there is peeling at the interface, the transmission to the substrate and the lower layer is weakened, and the energy is converted into the generation of surface waves, so the strength of the surface waves leaking into the air is large, The epoch-making fact that peeling can be detected by such a difference in the intensity of ultrasonic waves was confirmed.

Therefore, the present inventor does not examine the ultrasonic wave directly reflected from the interface and coming out of the test material as in the conventional reflection method using an ultrasonic medium, but in the sprayed coating, The invention of the present application is created in which separation of the interface is detected by detecting an ultrasonic wave (surface wave) leaking into the air after propagating between the surface and the interface.
In addition, the inventor of the present application can receive a strong reflected wave of the transmitted aerial ultrasonic wave if the sealing agent that is generally used is properly sealed, and the sealing is appropriately performed. Otherwise, we found that the reflected wave was weak. Although this phenomenon has not been fully elucidated at present, if an appropriate hole is sealed, airborne ultrasonic waves are strongly reflected on the surface of the sealing agent. It is considered that the ultrasonic waves reflected from the inside of the sealing agent are weakly reflected by the multiple reflection of the ultrasonic waves. Therefore, the inventor of the present application has found that the suitability of the sealing treatment can be accurately determined by using the reflected wave of the airborne ultrasonic wave.

Specifically, the first invention of the present application provides a method for inspecting a thermal spray coating having the following configuration.
That is, this method examines the peeling at the interface between the thermal spray coating and the substrate or the peeling at the interface between the thermal spray layers for the thermal spray coating having at least one thermal spray layer covering the substrate. Using a transmitter that emits ultrasonic waves toward the thermal spray coating and a receiver that receives ultrasonic waves from the thermal spray coating, the transmitter propagates the ultrasonic waves into the air and makes it enter the thermal spray coating. A receiver equipped with an aerial ultrasonic probe 1 and a receiver equipped with an aerial ultrasonic probe 2 for receiving ultrasonic waves propagating in the air from the thermal spray coating, respectively. Adopted, the probes 1 and 2 of the transmitter and the receiver are arranged above the sprayed coating, and the probe 1 of the transmitter is directed obliquely with respect to the film surface of the sprayed coating. In a state where the film surface of the coating is viewed in plan, the probe 2 of the receiving unit is connected to the probe 1 of the transmitting unit. It is placed on the extension of the direction. Then, an ultrasonic wave is incident on the thermal spray coating from the probe 1 of the transmission unit to propagate the surface wave in the thermal spray coating, and the intensity of the surface wave received by the probe 2 of the reception unit is determined. The presence or absence of peeling is examined by comparing with the strength of the surface wave when there is no peeling.
It should be noted that the thermal spray coating is assumed to be located on the base material, and that both the probes 1 and 2 are arranged above the thermal spray coating. However, such upper and lower positions are simply relative to each part. It is used for the sake of convenience in explaining the positional relationship, and the upper and lower positions are not defined by limiting the direction in which gravity is applied downward.

A second invention of the present application is the first invention of the present application, and provides a method for inspecting a sprayed coating having the following configuration.
That is, the above-mentioned surface wave travels in the direction along the interface while performing multiple reflections between the interface for examining delamination and the surface of the sprayed coating. This method is generated on the surface of the sprayed coating at the time of incidence. It is characterized by examining surface waves after attenuation of reflected noise.

According to a third invention of the present application, there is provided a thermal spray coating inspection apparatus according to the first or second invention of the present application, which adopts the following configuration.
That is, the probe 2 of the receiving unit receives surface waves leaking from the surface of the thermal spray coating, and the above-described distance between the probe 1 of the transmitting unit and the probe 2 of the receiving unit is , More than 3 times the thickness of the sprayed coating.

According to a fourth invention of the present application, in the invention according to any one of the first to third applications of the present application, a method for inspecting a sprayed coating having the following configuration is provided.
That is, both the air ultrasonic probes 1 and 2 are provided with a vibration part that oscillates when voltage is applied and generates an ultrasonic wave, and an acoustic matching member. The ultrasonic impedance can be propagated in the air while suppressing the difference in acoustic impedance between the transmitter and the air, the interval between the probe 1 of the transmitter and the probe 2 of the receiver, and the transmitter The distance between each probe of the receiver and the sprayed coating surface is within a range where it is not possible to determine separation due to attenuation of the ultrasonic wave being propagated. The probe 1 is at an angle of 30 degrees or more and 89.5 degrees or less with respect to the interface to be inspected. About the line perpendicular to the film surface of the thermal spray coating at the intermediate point between the two, Quito, and serves as a substantially line symmetric.
Here, all angles are defined in the range of 0 to 90 degrees, and obtuse angles and negative numbers are not used. For example, 80 degrees includes 80 degrees ± 90 degrees × n (n is an integer). Therefore, when it is 80 degrees, it includes 100 degrees and -80 degrees.

The fifth invention of the present application provides a thermal spray coating inspection apparatus having the following configuration.
That is, this apparatus examines the peeling at the interface between the sprayed coating and the substrate or the peeling at the interface between the sprayed layers with respect to the sprayed coating having at least one sprayed layer covering the substrate. A transmitter that emits ultrasonic waves toward the thermal spray coating and a receiver that receives ultrasonic waves from the thermal spray coating, the transmitter propagates the ultrasonic waves into the air and enters the thermal spray coating, An aerial ultrasonic probe 1 is provided, and a receiving unit is provided with an aerial ultrasonic probe 2 that receives ultrasonic waves propagating from the thermal spray coating in the air. The probe 2 of the receiving unit is oriented obliquely with respect to the film surface of the thermal spray coating, and the distance between the probe 2 of the transmitting unit and the probe 1 of the transmitting unit is opposed to the probe 1 of the transmitting unit in plan view. Open and place. The distance between the probe of the transmitter and the probe of the receiver is at least three times the thickness of the thermal spray coating. Then, this apparatus causes ultrasonic waves to enter the thermal spray coating from the probe of the transmission unit, generates surface waves in the thermal spray coating, and strengthens the surface waves received by the probe of the reception unit. It is characterized by examining the presence or absence of peeling by comparing the strength of the surface wave with no peeling.

6th invention of this application is the said 5th invention of this application, and provides the inspection apparatus of the sprayed coating which takes the following structure.
That is, the substrate is made of metal or ceramic, and the sprayed coating is formed by spraying metal, polymer, ceramic or cermet. The vibration frequency of each probe is 200 to 800 kHz. A scanning unit 10 is provided which holds both the probes 1 and 2 of the transmission unit and the reception unit and can scan the probes 1 and 2 along the surface of the thermal spray coating. The scanning unit 10 holds both the probes 1 and 2 of the transmission unit and the reception unit so as to be at least 5 times the thickness of the thermal spray coating and at intervals of 200 mm or less. Further, the scanning unit 10 holds the probes 1 and 2 at an interval of 5 mm to 80 mm from the surface of the thermal spray coating. And this apparatus detects the peeling in an interface by the change of the intensity of the received surface wave during a scan.

A seventh invention of the present application is the sixth invention of the present application, and provides a thermal spray coating inspection apparatus adopting the following configuration.
That is, the scanning unit 10 is mainly formed of a transparent material, and includes a transmission side holding unit 4 that holds the probe 1 of the transmission unit, a reception side holding unit 5 that holds the probe 2 of the reception unit, At least two casters 7 and 7 as front wheels and rear wheels are provided, and the probes 1 and 2 are held by holding the hands 7 and 7 on the film surface of the sprayed coating so that the casters 7 and 7 follow the sprayed coating. It is possible to scan along the film surface of the sprayed coating. Both casters 7 and 7 are formed of Teflon (registered trademark) resin at least on the surface. The transmission side holding unit 4 holds the probe 1 of the transmission unit at an angle of 30 degrees or more and 89.5 degrees or less with respect to a lower end line (virtual line) connecting the lower ends of the casters 7 and 7. The reception-side holding unit 5 then probes the reception unit so that the perpendicular (virtual line) perpendicular to the lower end line in the side view faces in a direction that is symmetrical with the direction of the probe 1 of the transmission unit. Hold child 2. Further, the transmission side holding unit 4 and the reception side holding unit 5 hold the probes 1 and 2 with an interval of 5 mm or more and 50 mm or less upward from the lower end line in the vertical direction. .

An eighth invention of the present application is the thermal spray coating inspection apparatus according to any one of the fifth to seventh inventions of the present application, which has the following configuration.
That is, this apparatus includes a sub-transmission unit that emits ultrasonic waves toward the thermal spray coating and a sub-reception unit that receives the ultrasonic waves from the thermal spray coating. The sub-transmission unit propagates the ultrasonic waves in the air and sprays it. The sub-reception unit includes an aerial ultrasonic probe that receives ultrasonic waves propagating in the air from the thermal spray coating. Both probes of the sub-transmission part and the sub-reception part are arranged above the sprayed coating. The direction of the probe of the sub-transmission unit is substantially perpendicular to the film surface of the thermal spray coating. The probe of the sub-transmission unit emits ultrasonic waves in the air toward the thermal spray coating, and the sub-reception unit. The state of the sealing treatment of the thermal spray coating is detected by receiving the ultrasonic wave returned from the thermal spray coating with the probe.

Therefore, the first to seventh inventions of the present application use an ultrasonic wave to determine whether or not the interface between the thermal spray coating and the base material or the interface between the thermal spray layers in the thermal spray coating is peeled off using the aerial ultrasonic waves. It was possible to investigate by non-destructive inspection.
For this reason, the sprayed coating is not soiled by the medium. In addition, since it is not necessary to provide means for supplying the medium, the apparatus can be miniaturized, can be inspected on site, and can be inspected quickly.
In particular, the presence or absence of delamination can be detected by investigating the strength of surface waves leaking out of the thermal spray coating using surface waves propagating zigzag between the coating surface and the interface in the thermal spray coating.
In addition, since both the transmitter and receiver probes can be placed above the thermal spray coating, the inspection can be performed on plant equipment where it is difficult to place the probe using a method that transmits air ultrasonic waves. It was possible to inspect such equipment on-site for sprayed coatings.
As described above, the present invention actively generates surface waves by obliquely making ultrasonic waves incident, and in a plan view, by placing a receiving probe at the destination of the waves, It was assumed that the ultrasonic waves leaking during propagation as waves were reliably detected.
As described above, the present invention prevents the contamination of the film by the liquid by eliminating the ultrasonic medium. However, as in the conventional ultrasonic inspection method, the ultrasonic medium is not used. When the probe is interposed between the probe on the receiving side and the thermal spray coating, the surface wave leaking to the surface of the thermal spray coating, which can be detected in the air, is significantly attenuated and cannot be detected. Therefore, by using airborne ultrasonic waves, it is possible to more reliably detect surface waves as well as to eliminate contamination of the film.

The surface wave is precisely an ultrasonic wave that travels in the thermal spray coating while reflecting between the interface between the thermal spray coating and the substrate and the surface of the thermal spray coating on each of the interface and the coating surface. .
In the second invention of the present application, the surface wave can be detected without being disturbed by noise caused by the incidence of ultrasonic waves on the thermal spray coating, and the peeling of the interface can be examined with high accuracy.
In the third invention of the present application, a more specific method for reliably detecting a surface wave without being disturbed by the noise is provided.
Specifically, rather than examining the reflected wave directly reflected from the interface for inspecting the peeling after the incident, the third invention of the present application is the transmission / reception unit of the transmitter / receiver that the present inventor has eagerly studied and further discovered through trial and error. By setting the distance between the two probes, the ultrasonic wave propagated along the interface with the thermal spray layer as a surface wave. Among the ultrasonic waves that leaked into the air (above the thermal spray coating) through the thermal spray coating, It was assumed that it was possible to reliably detect those that were less affected by the reflected wave generated on the surface of the sprayed coating when incident.
That is, the surface wave leaks into the air from the surface of the sprayed coating through the particles of the sprayed coating at each position in the traveling direction, but by setting the interval between the probes described above. By detecting the leaking ultrasonic waves that do not overlap with the noise near the incident position, it is possible to investigate the presence or absence of peeling.

According to the fourth aspect of the present invention, the probe of the transmission unit is set at a more preferable angle with respect to the film surface of the thermal spray coating.
Although the surface of the sprayed coating is microscopically observed, there are undulations, but when viewed macroscopically as the film surface of the sprayed coating, the film pressure of the sprayed coating is formed almost uniformly at each position. The surface is substantially parallel to the substrate surface, that is, the interface between the thermal spray coating and the substrate. Therefore, although the interface cannot be seen from the outside, the angle taken by the probe with respect to the film surface can be considered as the angle with respect to the interface.
As for the sprayed coating formed of a plurality of sprayed layers, the thickness of each position is substantially uniform for each of the sprayed layers, so the interface of each of the above layers is macroscopically about the plane of the film. The angle with respect to the film surface of the probe described above can be considered as the angle with respect to the interface between the layers.
In addition, the normal uniform material causes the refraction of the ultrasonic wave upon incidence due to the difference between the sound velocity in the material on one side with respect to the interface and the sound velocity in the material on the other side with respect to the interface. However, such an angle of refraction does not need to be taken into account for the ultrasonic waves in the thermal spray coating propagating between the agglomerates.

The fifth invention of the present application can provide an inspection apparatus suitable for carrying out the inspection method according to the present invention.
In particular, in the sixth invention of the present application, both the probes are scanned along the surface of the thermal spray coating by the scanning unit, and the intensity of ultrasonic waves leaking from the surface of the thermal spray coating received by the probe of the reception unit is measured. The change detects the separation at the interface, and the presence or absence of the separation at the interface can be checked for each part of the sprayed coating.
In the seventh invention of the present application, a more specific means for inspecting the peeling of the interface can be provided. In particular, according to the present invention, it is possible to more smoothly perform an on-site peeling inspection such as plant equipment by holding each of the transmission / reception probes in a scanning unit that can be scanned by hand. Can do. Further, by making the scanning portion transparent, scanning can be performed while looking at the surface of the sprayed coating, and the surface of the sprayed coating can be traced reliably.
In the eighth invention of the present application, the state of sealing of the sprayed coating can be checked. In other words, if the pores of the thermal spray coating are properly sealed, a strong reflected wave can be received from the uniform sealing agent inside, but the pores reach the substrate without being properly sealed. If so, the ultrasonic wave reflected from the sealing agent becomes weak. The suitability of the sealing can be examined by the strength of the reflected wave.

As described above, in the present invention, the ultrasonic wave incident on the sprayed layer is penetrated into the sprayed layer using a transmitter (transmitting probe) installed obliquely, and the generated surface waves are applied to the sprayed layer and Then, it was possible to propagate the interface between the sprayed layer and the base material and detect ultrasonic waves leaking in the air with a receiver (referred to here as a receiving probe) to examine the interface properties from the intensity.
Therefore, it enables early detection of under-film damage that cannot be visually observed, such as whether spraying has been performed on a clean blasted surface during spraying, detection of blistering or peeling of the film, etc. Can be expected to be used in a wide range of fields.
In addition to such advantages (in the eighth invention of the present application), a location where the sealing is insufficient can be detected quickly, so that the sealing process can be redone, and the most suitable sealing agent is selected. Also show power. It is also possible to easily check on site whether or not an aged sprayed layer has a sufficient insulating function.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic side view of an inspection apparatus according to an embodiment of the present invention, which is a cross-sectional view of a scanning unit. FIG. 2A is an explanatory view in which the main part of FIG. 1 is viewed from the side, and FIG. 2B is an explanatory view of surface waves. FIG. 3 is a schematic side view showing a use state of the inspection apparatus of FIG. FIG. 4 is a schematic side view showing another embodiment of the scanning unit. FIG. 5 is an explanatory diagram showing a scanning position of a peeling test performed on a sample having peeling, which is performed using this apparatus. FIG. 6 is an explanatory diagram showing the test results of the sample. FIG. 7 is an explanatory diagram showing the relationship between the amplitude of the ultrasonic wave received in the test and the scanning position. FIG. 8 is an explanatory diagram showing the relationship between the amplitude of an ultrasonic wave received in a peel test performed on a sample different from that in FIG. 7 and the scanning position. FIG. 9A is an explanatory view showing a microscope image of a sample having the above-described peeling, and FIG. 9B is an explanatory view showing a microscope image of a healthy sample without peeling. FIG. 10 is an explanatory view showing the inspection position of the sealing inspection performed using the above-described apparatus. FIG. 11 (A) is an explanatory view showing the relationship between the amplitude of ultrasonic waves and the time for pores that are not sealed for the aluminum sprayed coating in the ferroxyl test, and FIG. 11 (B) is the seal sealed for the aluminum sprayed coating. It is explanatory drawing which shows the relationship between the amplitude of an ultrasonic wave, and time about what is made appropriately. FIG. 12 (A) is an explanatory diagram showing the relationship between the amplitude of ultrasonic waves and time for pores that are not sealed with respect to the ceramic sprayed coating, and FIG. 12 (B) is a diagram showing appropriate sealing with respect to the ceramic sprayed coating. It is explanatory drawing which shows the relationship between the amplitude of an ultrasonic wave, and time about what is made. FIG. 13 is an explanatory diagram showing the relationship between the amplitude of the received ultrasonic wave and the scanning position for the aluminum sprayed coating shown in FIG. FIG. 14 is an explanatory diagram showing the relationship between the amplitude of the received ultrasonic wave and the scanning position for the ceramic sprayed coating shown in FIG. FIG. 15 (A) is an explanatory view showing the result of a ferroxyl test for a ceramic sprayed coating that is not properly sealed, and FIG. 15 (B) is a diagram showing a properly sealed ceramic sprayed coating. It is explanatory drawing which shows the result of a ferroxyl test about. FIG. 16 is an explanatory diagram of a graph showing the relationship between the reflected ultrasonic intensity in the ceramic sprayed coating and the blue spots by the ferroxyl test.
In the figure, U indicates the upper side, S indicates the lower side, F indicates the front side, and B indicates the rear side.

The apparatus includes an aerial ultrasonic wave transmission unit and an aerial ultrasonic wave reception unit.
Specifically, as shown in FIG. 1, this apparatus includes an aerial ultrasonic wave transmission probe 1, an aerial ultrasonic wave reception probe 2, and an aerial ultrasonic wave transmission / reception probe 3. The scanning unit 10 holding these probes 1 to 3 and the encoder, the signal processing unit 11 formed separately from the scanning unit 10 and connected to the probes 1 to 3, and the signal processing unit 11 and a data processing unit 13 connected to the waveform display unit 12.

The transmission probe 1 for airborne ultrasonic waves is a transmitter capable of propagating ultrasonic waves in the air, and includes a vibrator that receives an excitation signal from the signal processing unit 11 and vibrates.
The above-described receiving probe 2 for aerial ultrasonic waves includes a vibrator that vibrates in response to ultrasonic waves propagating in the air, converts the vibration into a signal, and sends the signal to the signal processing unit 11.
The sub probe 3 for transmitting and receiving airborne ultrasonic waves includes a transducer that propagates ultrasonic waves in the air and receives ultrasonic waves propagated in the air.
As described above, the sub-probe 3 has been shown to be used for both transmission and reception of aerial ultrasonic waves. However, as with the other probes 1 and 2, the sub-probe also transmits and receives. Each can be implemented independently. However, when both transmission and reception are combined with one probe, it is easier to adopt an arrangement in which ultrasonic waves are incident perpendicularly to the film surface of the sprayed coating, and the scanning unit 10 can be saved. It is preferable in terms of space.

Airborne ultrasound uses longitudinal waves that are less attenuated in air.
Each of the above-described aerial ultrasonic probes 1 to 3 includes a vibration part and an acoustic matching member provided on the vibration surface of the vibration part.
The vibration unit is a piezoelectric element, and vibrates by applying a signal voltage in the probe 1 of the transmission unit, and converts the vibration into a signal voltage in the probe 2 of the reception unit. The acoustic matching member is a member having an acoustic impedance larger than air and smaller than that of the piezoelectric element. A zircon lead titanate (PZT) or a composite vibrator can be used for such a vibration part. The acoustic matching member is made of a material using clay, resin, polyurethane, and is formed as a layer on the surface of the vibration surface of the vibration unit, or a member provided on the vibration unit as a part of the vibration unit. be able to.

More specifically, each of the above probes 1 to 3 is provided with clay (clay) as an acoustic matching layer on the transmitting surface of the piezoelectric element made of zircon lead titanate (PZT) described above. The product made by Ultra can be adopted. In addition, the above-described probes 1 to 3 can employ a composite voltage transducer including the above-described sensor called a composite. This composite voltage transducer is obtained by replacing a part of the PZT element with a composite material having a low acoustic impedance, and using an epoxy as the above resin or a composite material using polyurethane. Can be adopted.
Although it is possible to employ one using the above-mentioned capacitor, this type needs to apply a bias voltage to the electrodes sandwiching the capacitor as described above. Two types are preferably employed.
In the type employing a polymer piezoelectric film (PVDF), the frequency is usually several megahertz in a metal or ceramic microscope, and the attenuation is large and difficult to use for an airborne ultrasonic wave.

The signal processing unit 11 includes a pulsar 11a that excites the above-described transmission probe 1 for aerial ultrasound, a receiver 11b that amplifies a signal from the reception probe 2 for aerial ultrasound, and an A-D converter ( And a control unit (not shown).
The pulsar 11 that has received a command from the control unit transmits an excitation signal to the transmission probe 1 to vibrate the transducer of the transmission probe 1 and transmit an aerial ultrasonic wave.
The receiver 11b receives the signal from the receiving probe 2, amplifies the signal, and sends it to the A-D converter.

The AD converter converts the analog signal into a digital signal and sends it to the waveform display unit 12.
The waveform table 12 receives a signal obtained through the AD converter 12 of the signal processing unit 11 and displays a waveform with an A scope (A mode). The waveform display unit 12 is preferably a digital oscilloscope.
In addition, the data processing unit 13 can acquire waveform data from the waveform display unit 12, store it, and print it out. A commercially available computer can be used for the data processing unit 13. In particular, it is preferable in terms of portability to employ a notebook personal computer for the data processing unit 13.
The person who performs the inspection, that is, the operator can determine whether or not the inspection object is peeled off and whether or not the sealing process is appropriate by looking at the waveform display unit 12 or by viewing the waveform data printed out. In the determination of the presence or absence of peeling, it can be confirmed by examining the intensity of the received wave, that is, the change in the amplitude of the waveform in the A scope.

  As described above, the transmission unit mainly includes the above-described probe 1 for transmitting an ultrasonic wave, the pulsar 11a of the signal processing unit 11, and the control unit. As described above, the receiving unit mainly includes the above-described probe 2 for receiving the aerial ultrasonic wave, the receiver 11b of the signal processing unit 11, the A-D converter, the control unit, and the waveform display unit. Consists of.

The transmission probe 1 and the reception probe 2 are used for a thermal spray coating peeling test. The transmission / reception sub-probe 3 is used for inspection of sealing treatment. As described above, in the embodiment, the inspection device serves as both a spray coating peeling inspection and a sealing inspection device.
In this embodiment, the sub-processing probe 3 is connected to the pulsar 11a of the signal processing unit 11 and the receiver 11b, and an operator selects whether to perform peeling inspection or sealing inspection. The control unit receiving the pulser 11a sends an excitation signal corresponding to the probe to either the transmission probe 1 or the sub probe 3, and the receiver 11b receives the reception probe 2 The signal sent from either of the sub-probe 3 is processed.
The peeling inspection and the sealing inspection are selected by switching the probe commanded by the control unit.

Although the illustration of the means for inputting the selection of the inspection is omitted, here, the signal processing unit 11 includes such an input means. However, the present invention can be implemented, for example, by connecting a computer constituting the data processing unit 13 to the control unit and receiving an input from the computer.
Although not shown, the transmitting probe 1, the receiving probe 2, and the sub-probe 3 can be implemented by being connected to separate pulsars and receivers, respectively. Moreover, this apparatus can also be implemented without providing the sub-probe 3 as an apparatus dedicated to peeling inspection.

The scanning unit 10 holds the transmission-side holding unit 4 that holds the transmission probe 1, the reception-side holding unit 5 that holds the reception probe 2, and the sub-probe 3. Sub-holding section 6, casters 7..., And an encoder (not shown).
The scanning unit 10 has a size and a weight that can be grasped with one hand. The main body of the scanning unit 10 is formed as a gripping unit. The main body of the scanning unit 10 (a portion excluding the casters 7... 7 and the encoder) can be formed of plastic, and is preferably formed of a transparent polymer material. This is because, by employing a transparent material, scanning can be performed while observing the surface of the sprayed coating. In particular, it is preferable to employ an acrylic material for the scanning unit 10 body.
In this embodiment, as shown in FIG. 1, the scanning unit 10 is a rectangular parallelepiped having an upper surface 10a, a lower surface 10b, left and right side surfaces, a front surface 10c, and a rear surface 10d, and the front and rear width (length w1) is about 100 mm. The vertical width (the height w2 from the lower surface 10b to the upper surface) is about 40 mm, and the left and right width is about 60 mm. Such numerical values can be variously changed. However, considering the securing of the gap w3 between the transmitting and receiving probes 1 and 2 necessary for the peel inspection and the ease of gripping, the front-rear width is 50-300 mm and the upper-lower width is 10-100 mm. It is preferable that the left and right (between side surfaces) width is 40 to 70 mm, particularly 60 to 70 mm.

The plurality of casters 7... 7 of the scanning unit 10 are preferably made of resin, particularly those made of Teflon (registered trademark) resin. This is because the use of a Teflon (registered trademark) caster can prevent contamination of the sprayed surface with metal. Each caster 7... 7 is fixed to the main body of the scanning unit 10. In this embodiment, a part of the caster 7... 7 is a front wheel of the scanning unit 10 and another part of the caster 7. The rear wheel of the scanning unit 10 is used.
The scanning unit 10 is preferably provided with four casters 7... 7 constituting left and right front wheels and left and right rear wheels. In this embodiment, as shown in FIG. 1, in the front-rear direction, the transmission side holding portion 4 is provided in front of the casters 7, 7 that are rear wheels, and the sub holding portion 6 is provided in front of the transmission side holding portion 4. In addition, a receiving side holding unit 5 is provided in front of the sub holding unit 6, and casters 7 and 7 serving as front wheels are provided in front of the receiving side holding unit 5. The front-rear direction is the scanning direction, and the positional relationship between the front and rear of the transmission unit side holding unit 4 and the reception side holding unit 5 may be opposite to the above.
In addition, as described above, the probes 1 and 2 are not limited to those that have a front-rear positional relationship with respect to the scanning direction. For example, the present invention can be implemented even if the probes 1 and 2 are arranged in the left-right direction intersecting the scanning direction with the scanning direction as the front-rear direction.

The encoder indicates the position of the scanning unit 10 on the surface of the test material (on the surface of the thermal spray coating), and is connected to the control unit.
As the encoder, a rotary encoder that indicates the traveling position of the scanning unit 10 by the rotation of the caster 7 can be employed.

As shown in FIG. 1, each of the transmission side holding unit 4, the reception side holding unit 5, and the sub holding unit 6 is a through-hole penetrating from the upper surface 10 a to the lower surface 10 c of the scanning unit 10. Each holding | maintenance part 4-6 is provided with the inner shape and dimension corresponding to the external shape and dimension of a probe, and the probes 1-3 are each fitted.
Specifically, for the cylindrical probes 1 to 3, the holding portions 4 to 6 are formed in the main body of the scanning unit 10 as a cylindrical hollow portion having an inner diameter substantially equal to the outer diameter of the probe. Is done.
The probes 1 to 3 are fitted to the holding portions 4 to 6 with the vibration surfaces 1a, 2a, and 3a facing downward.
The probes 1 to 3 are fixed to the scanning unit 10 using bolts. However, each probe can be fixed using a known fixing means other than bolts, nuts and screws, for example, an adhesive.

In the side view of the scanning unit 10, as shown in FIG. 1, the transmission side holding unit 4 has its direction, that is, the axial direction (the direction of the dashed line drawn on the transmission side holding unit 4 in FIG. 1) at the lower end of the front wheel caster 7. With respect to a line segment perpendicular to the lower end line x connecting the lower end of the rear wheel caster 7 (hereinafter referred to as a vertical line as necessary), it is formed in a state inclined 0.5 to 30 degrees rearward. Yes. That is, the direction of the transmission side holding unit 4 is such that the lower end opening is directed obliquely forward from below with an angle of 30 degrees to 89.5 degrees with respect to the lower end line x.
By fitting the transmission probe 1 to the transmission side holding portion 4 as described above, the vibration surface 1a of the transmission probe 1 is set to 30 degrees to 89.5 with respect to the lower end line x. It is directed obliquely forward from below with an angle θ of degrees. That is, the transmission probe 1 can transmit an aerial ultrasonic beam in the direction of an angle θ of 30 degrees to 89.5 degrees with respect to the lower end line x. The aerial ultrasonic wave transmission probe 1 has directivity, but has a certain extent of ultrasonic wave, so that the supersonic wave of 30 degrees to 89.5 degrees with respect to the lower end line x here is super The sound wave is transmitted in the direction of the central beam of the ultrasonic wave emitted from the vibration surface 1a.
With respect to the lower end line x, if the angle θ is less than 30 degrees, the inclination is too large, and the aerial ultrasonic waves cannot be appropriately incident on the thermal spray coating. It is almost perpendicular to the surface and cannot generate surface waves.

  In particular, the angle θ with respect to the lower end line x is 70 degrees to 89 degrees when the sprayed coating to be inspected is formed by aluminum spraying in the peel inspection (the angle of the lower end line x with respect to the perpendicular is 1 degree to 20 degrees), and when formed by ceramic spraying, it is preferably 77 degrees to 84 degrees (the angle of the lower end line x with respect to the perpendicular is 6 degrees to 13 degrees).

In the plan view of the scanning unit 10, the reception side holding unit 5 is located on an extension of the axis of the transmission side holding unit 5.
In the side view of the scanning unit 10, the reception side holding unit 5 is line-symmetric with the axial direction of the transmission side holding unit 4 with respect to the vertical bisector y of the lower end line x as shown in FIG. 1. The axial direction (the direction of the alternate long and short dash line shown in the receiving side holding unit 5 of FIG. 1) is directed to
Therefore, when the transmission side holding unit 4 is tilted 82 degrees backward (so that θ = 82 degrees counterclockwise in FIG. 1), the reception side holding unit 5 is 82 degrees forward (clockwise in FIG. 1). It is preferably formed in an inclined state (so that φ = 82).
In order to generate a surface wave, it is necessary to tilt the probe on the transmitting side as described above. On the other hand, if the surface wave can be received, the direction of the probe on the receiving side is as described above. As described above, the present invention can be implemented without adopting a symmetrical positional relationship with the transmitting probe. For example, if the distance between the probes 1 and 2 is small, the probe can be implemented without tilting.

  By fitting the receiving probe 2 to the receiving side holding unit 5 as described above, the direction of the receiving probe 2 is changed with respect to the vertical bisector y. It can arrange | position so that it may become line symmetrical with direction of 1.

The tip surfaces of the cylindrical probes 1 and 2 are vibration surfaces 1a and 2a. The distance between the center points of the circles of the contours of the vibration surfaces of the probes between the probes 1 and 2 for transmission and reception is defined as the distance between the probes 1 and 2. When the probe is a polygonal column, the interval between the center of gravity of the polygon that the vibration surface exhibits is set as the interval w3 between the probes 1 and 2.
As shown in FIG. 2 (A), this interval w3 attenuates reflection noise (hereinafter referred to as surface reflection wave t) at the incident position on the surface of the coating among the sound waves received by the probe 2 for reception. It is assumed that the subsequent surface wave KW can be received.
The surface reflected wave t is generated when the ultrasonic wave transmitted from the transmission probe 1 is reflected by the sprayed coating surface MS at the time of incidence, and the transmission probe 1 receives the probe for reception. If it is too close to the child 2, the ultrasonic wave reflected from the interface position such as the surface wave KW is hidden in the shadow of the surface reflected wave t, and it becomes difficult to detect peeling. Accordingly, the interval W3 is set to a sufficient size so that the surface wave KW after the surface reflected wave t is attenuated can be received so that the surface reflected wave t does not get in the way of noise.
As described above, by mounting the transmission probe 1 on the transmission side holding unit 4 and mounting the reception probe 2 on the reception side holding unit 5, the interval w3 can be secured. Thus, the interval between the transmission side holding unit 4 and the reception side holding unit 5 is set in advance.
In this embodiment, the distance w4 with respect to the lower end line x of the probe 1 of the transmitting unit is the same as the distance w5 with respect to the lower end line x of the probe 2 of the receiving unit (FIG. 1).

From the viewpoint of increasing the decay time of the above-described surface reflection wave, the interval w3 is 3 times or more, preferably 4 times or more, particularly preferably the thickness of the sprayed coating in any of the aluminum sprayed coating and the ceramic sprayed coating. The interval w3 is set so as to be 5 times or more the thickness. However, since the surface wave is also attenuated, the intervals w3, w4, and w5 are set within a range in which the reception probe 2 cannot receive the appropriate surface wave due to the attenuation of the surface wave.
Specifically, the vibration frequency of the probes 1 and 2 can be set to 200 to 800 kHz, and the output voltage (spike voltage) of the pulsar can be set to 150 to 300 V. The distance between the transmitting and receiving probes 1 and 2 having the angles θ and φ, that is, the distance w3 between the centers of the vibration surfaces 1a and 2a of the transmitting and receiving probes 1 and 2 is 10 to 100 mm.
Further, in this case, the center (shortest) distance w4 of the vibration surface 1a of the transmitting probe 1 with respect to the lower end line x and the (shortest) distance w5 of the center of the vibration surface 2a of the receiving probe 2 with respect to the lower end line x. Are 5 to 30 mm, and w4 and w5 are preferably 10 to 25 mm, and most preferably 10 mm.
When a commercially available probe is used, a pulsar output voltage of 200V can be used.
Also, the sub-probe 3 may be one having a vibration frequency of 200 to 800 kHz, preferably a vibration frequency of 200 to 500 kHz.
Note that the distance w4 and the distance w5 may be different from each other within the above range.
The transmission side holding unit 4 of the scanning unit 10 is provided with respect to the reception side holding unit 5 so that the probes 1 and 2 have the above positional relationship.

  In the side view of the scanning unit 10, the axial direction of the sub holding unit 6 is perpendicular to the lower end line x. By fitting the sub-probe 3 to the sub-holding portion 6, the sub-probe 6 makes the axial direction (center beam) perpendicular to the lower end line x.

  On the other hand, although not shown in the drawings, the holding units 4 to 6 are configured so that the left and right casters of the front wheel and the rear wheel are in front view of the scanning unit 10, that is, in a state where the scanning unit 10 is viewed from the front or the rear of the scanning unit. The axial direction (the direction of the one-dot chain line in FIG. 1) is perpendicular to the line segment connecting the lower ends (the line segment perpendicular to the lower end line x in plan view). That is, in a state where the scanning unit 10 is viewed from the front, the angle probes 1 to 3 make the axial direction perpendicular to the line segment connecting the lower ends of the left and right casters.

As shown in FIG. 3, the inspection apparatus having the above-described configuration is carried to the site where the thermal spray coating M is provided (base N), the operator holds the scanning unit 10 by hand, and the surface of the thermal spray coating. Make MS imitate.
At this time, by bringing the casters 7... 7 into contact with the surface of the thermal spray coating M, the respective angles .theta., .Phi. , W6. Then, by manually sliding the scanning unit 10 on the sprayed coating, it is possible to inspect the presence or absence of peeling at each part of the sprayed coating.
As shown in FIG. 2 (B), the aerial ultrasonic wave transmitted from the transmitting probe 1 is incident obliquely into the thermal spray coating, and the ultrasonic wave after the incident is a surface wave KW, and the thermal spray coating M and the substrate. It propagates along the interface K while reflecting between the interface K of N and the sprayed coating surface MS. At this time, a part of the surface wave KW leaks into the air from the sprayed coating surface MS, and the leaked surface wave KW can be detected by the receiving probe 2.
The surface wave is a Rayleigh wave. Further, an interface wave is generated together with this surface wave (not shown). The interface wave is a sound wave that propagates linearly along the interface between the substrate and the thermal spray coating. Investigate the presence or absence of delamination by detecting the intensity of the interfacial wave (Stonery wave) leaking from the thermal spray coating along with the above interface wave as the strength of the sound wave propagating along the interface in the thermal spray coating. Can do.
The above Stoneley wave is a wave that propagates along a boundary while generally concentrating energy at a heterogeneous interface and attenuating in a manner similar to a Rayleigh wave into the inside of both materials.
As described above, the interface wave (Stonley wave) and the surface wave (Rayleigh wave) are macroscopically the same in that they are sound waves propagating along the interface in the thermal spray coating. With respect to the above-mentioned surface wave, it can be used for detection of peeling.

Similarly, when the sealing inspection is performed, the sub probe 3 can be scanned along the thermal spray coating by manually causing the scanning unit 10 to follow the surface of the thermal spray coating.
The peeling inspection and the sealing inspection are performed by switching as described above. When both the peeling inspection and the sealing inspection are performed, any inspection may be performed first. When one of the inspections is completed, the probe to be used may be switched through the control unit, and either one of the inspections may be performed.

  On the premise of securing the width w3 shown in FIG. 1, which is necessary for performing the peeling inspection of the present invention, it is more portable and easier to perform hand-held scanning if the width w1 before and after the scanning unit 10 is made as small as possible. Therefore, in the embodiment shown in FIG. 1, the arrangement of the sub-holding unit 6 installed between the transmission-side holding unit 4 and the receiving-side holding unit 5 is as shown in FIG. The scanning unit 10 can be formed more compactly by being disposed at either the left or right of the transmission side holding unit 4 at substantially the same position as the unit 4. In addition, it can also be implemented by providing the sub-holding unit 6 at approximately the same position as the receiving-side holding unit 5 for F and B in the front-rear direction.

  In addition, in order to excite the transducers of the above-described probes 1 to 3, in addition to applying a pulse voltage, a wave called a chirp wave whose frequency changes with time can be applied. A sensor having a resonance frequency may be selected from well-known sensors and used for the purpose. The airborne ultrasonic waves detected by the sensor can be observed in situ using a digital oscilloscope. For this reason, it can be judged on the spot whether the amplitude changes, and can also be recorded on a notebook computer. The inspection position can also be recorded by the encoder.

Regarding the thermal spray coating that can perform peeling inspection and sealing inspection according to the present invention, the general thermal spray coating formed of various thermal spray materials such as metal, polymer thermal spray coating, ceramic thermal spray coating, cermet thermal spray coating, etc. set to target.
In particular, when a steel material is used as a base material, it is possible to perform a good inspection on a typical aluminum spray coating or a ceramic spray coating as a metal spray.
For example, as a coating by metal spraying, a thermal spray coating by aluminum, alumina, aluminum alloy, nickel alloy represented by nickel-cobalt alloy and nickel-chromium alloy, titania, and other metals and alloys should be inspected. Can do. In addition, as a coating by ceramic spraying, it is possible to inspect a coating by an oxide ceramic, a carbonized ceramic, a nitride, or other ceramics.
In addition, in this sealing inspection, all sealing agents generally used can be set as inspection targets.
Specifically, sealants containing organic silicon such as silicon-epoxy, silicon-urethane, and silicon-phenol, inorganic silicon, epoxy, tar-epoxy, and vinyl-based resin as a component are to be inspected. be able to.

Hereinafter, each test result is demonstrated in order about the test | inspection (peeling state) of an interface state, and a sealing | blocking test | inspection performed using the apparatus shown in FIG.
In order to examine the effectiveness of the present invention in the inspection of the interface state, the following two types of samples (test pieces) were used.

(Sample No. 1)
An oil spot (oil film) is applied to the center of the surface of a square test piece in plan view after blasting, and then aluminum is sprayed (Sample No. 2)
After blasting, an oil spot (oil film) is attached to the center of the surface of a square test piece in plan view, and then aluminum is sprayed and treated with metalact and sealant

As shown in FIG. 5, Samples No. 1, 2 are both thermally sprayed on a square carbon steel plate having a length and width of 200 mm, and an oil spot H having a diameter of about 15 mm is present in the center of the square when viewed in plan. The oil spot H is a simulation of the blast surface stain, and this part is poorly adhered because the oil is interposed between the base material and the sprayed coating.
The scanning unit 10 (not shown) used in this test holds the transmitting probe 1 and the receiving probe 2 at a distance of 60 mm in the scanning direction (from left to right in FIG. 4). It is. The distance between both probes 1 and 2 for transmission and reception and the surface of the film is 10 mm. The dimension setting of each part of the scanning unit 10 is also as described above, and the angle θ of the transmission probe 1 is 82 degrees (8 degrees with respect to the vertical line y). The angle φ of the receiving probe 2 is symmetrical with the direction of the transmitting probe 1 in the previous line.
As shown in FIG. 5, the scanning unit 10 was inspected by sequentially scanning from left to right along seven parallel scanning lines I, II, III, VI, V, VI, and VII. .
In this inspection, since there are oil spots on the scanning line IV, it can be said that if an oil spot is detected as a poor adhesion position on this scanning line, appropriate peeling can be detected. There are no defects on the scanning lines other than the scanning line IV.
As shown in FIG. 5, the left and right positions (in the scanning direction) of each scanning line are indicated by scales a to w set at intervals of 5 mm.

FIG. 6 shows the waveform of the A scope of the airborne ultrasonic wave detected when the surface of sample No. 1 is scanned. 6 correspond to the positions of the scales a to w in FIG.
As can be seen from FIG. 6, the amplitude of the detection wave becomes extremely large when the defective portion (oil spot H) is directly under the transmitting probe 1 or under the receiving probe 2. Yes. That is, when the waveform is observed while scanning the scanning unit 10 on the sample surface, it can be seen that the interface property of the portion where the waveform having a large amplitude is detected is not good (peeling occurs).

The results of examining the amplitude distribution of the detected wave are shown in FIG. 7 for sample No. 1 and FIG. 8 for sample No. 2 respectively.
7 and 8, the black circles indicate the amplitude distribution in the scanning line II in the healthy area, and the white triangles in the scanning line IV with the oil spots. In FIGS. 7 and 8, since surface waves with large amplitude are detected at both ends of the oil spot on the scanning line, it can be seen that the adhesion failure portion exists in the valley portion with small amplitude.
FIG. 9A shows an image of a micrograph of a vertical cross section of the oil spot portion of sample No. 1. FIG. 9B shows an image of a micrograph of a vertical cross section of a healthy part of sample No. 1. As can be seen from FIG. 9A, peeling is observed between the film and the base material at the oil spot, but as can be seen from FIG. 9B, a good adhesion structure can be observed at the healthy portion. .

When the surface wave is peeled off, energy is not dissipated, so that the surface wave becomes a strong reflection echo and propagates through the film. For this reason, as described above, it is considered that delamination or delamination between the substrate and the film can be detected.
In normal oblique flaw detection in which ultrasonic waves are incident inside a uniform solid, it is necessary to determine the incident angle with respect to the test material in consideration of the refraction angle. It propagates between the agglomerates constituting the sprayed coating, and does not need to take into account the refraction angle.

Next, the sealing inspection will be described. Here, using the apparatus shown in FIG. 1, the sub probe 3 was used for inspection. The vibration surface of the sub probe 3 was separated from the surface of the sprayed coating by 10 mm. The orientation of the sub probe 3 is perpendicular to the film surface of the thermal spray coating as shown in FIG.
In this inspection for sealing quality, the quality of the sealing is determined from the reflection intensity of the airborne ultrasonic wave.
The following two types of samples A and B were used for verification.

That is,
Sample A-1 is aluminum sprayed and not sealed.
Sample A-2 was subjected to sealing by aluminum spraying.
Sample B-1 is ceramic (102) sprayed and not sealed.
Sample B-2 was ceramic (102) sprayed and sealed.

  Each sample was obtained by thermal spraying an oxygen-acetylene flame on a carbon steel substrate (SS400 / thickness 8 mm), and the film thickness was 150 μm. As described above, two types of samples were prepared, one not sealed (for example, A-1) and one sealed (A-2). The sealing agent used for the test is silicon resin KR251 manufactured by Shin-Etsu Chemical Co., Ltd. for both aluminum spraying and ceramic spraying.

FIG. 10 shows measurement points (a to t) (measurement point symbols indicate observation points in this sealing inspection, and are used separately from the alphabetic symbols shown in FIGS. 5 to 8).
Specifically, as shown in FIG. 10, in plan view, points from point a to point s, which are set in a rectangular range of 15 mm in length and 15 mm in width, with an interval of 5 mm in length and width, respectively. Measurement points were used.

  FIG. 11 shows the A scope waveform detected in the aluminum sprayed samples (A-1, A-2). This wave has been averaged 512 times to reduce the measurement error, but the time required for this averaging is approximately 0. Since it is 1 second, it can be measured while moving the scanning unit 10 of the apparatus shown in FIG. However, in practice, many such averages are not always necessary. FIG. 11A shows the waveform of sample A-1 that is not sealed, and FIG. 11B shows the waveform of sample A-2 that is sealed. As shown in FIG. 11, the maximum amplitude of the sealing treatment sprayed layer is larger than that of the sample without sealing.

  FIG. 12 shows A scope waveforms detected in the ceramic spray samples (B-1, B-2). FIG. 12A shows the waveform of sample B-1 which is not sealed, and FIG. 12B shows the waveform of sample B-2 which is sealed. As shown in FIG. 12, since the amplitude of the wave is considerably different between the unsealed sample and the sealed sample, the quality of the sealing can be determined by visual observation of the wave. In FIGS. 11 and 12, the first wave seen up to 50 μs is noise at the time of voltage transmission, and the wave seen at about 120 μs is a reflected wave (inspected wave). The time difference between the two depends on the distance w6 (lift-off distance) between the sensor and the sprayed surface, so that lift-off needs to be 10 mm or more.

FIG. 13 compares the reflected wave amplitude values (Vpp, values from + peak to −peak) of the aluminum spray samples A-1 and A-2, and FIG. 14 shows the ceramic spray samples B-1 and B−. The Vpp of 2 is compared. The horizontal axes of the graphs of FIGS. 13 and 14 correspond to the observation points a to t shown in FIG.
13 and 14, the reflection amplitude of the sample with the black square point sealed and the reflection amplitude of the sample with the white square point not sealed are shown.
As shown in FIGS. 13 and 14, the black squares indicating the sealed holes in both the aluminum sprayed and ceramic sprayed samples are larger than the open squares indicating the unsealed holes. This difference in amplitude is particularly noticeable in the ceramic spray sample B.

In order to demonstrate the effectiveness of the proposed method, the correspondence with the ferroxyl test was examined.
FIG. 15 shows the ferroxyl test results of Sample B. FIG. 15A shows the ferroxyl test results of ceramic sprayed non-sealing sample B-1, and FIG. 15B shows the ferroxyl test results of ceramic sprayed sealing sample B-2.
In the unsealed sample B-1 shown in FIG. 15A, large spots are observed, but the number is small. In the sealing treatment sample B-2 shown in FIG. 15B, the number of spots is extremely small, indicating that the sealing is well performed. From this, it can be confirmed that the results agree well with the results shown in FIG.
Next, the relationship between the number of spots and reflectance by a ferroxyl test was examined using Sample B-2 (sealing treatment for ceramic spraying). Since the blue spots in the ferroxyl test mean that there are unsealed vacancies, the relationship between the number of spots and the reflectance was investigated.

FIG. 16 shows the relationship between the intensity of the reflected ultrasonic wave of Sample B-2 and the number of blue spots (penetrating holes) by the ferroxyl test.
In FIG. 16, the intensity of the reflected ultrasonic wave of sample B-2 is indicated by a black diamond point, and the number of blue spots according to the ferroxyl test per square centimeter is indicated by a black dot. The horizontal axis in FIG. 16 corresponds to the observation points a to t in FIG.
It can be seen from FIG. 16 that the reflection intensity is reduced where the number of spots is large. That is, in this method, if the reflected ultrasonic intensity (black diamond points) and the number of blue spots per unit (black dots) tend to contradict each other, the sealing inspection can be performed appropriately. As shown in FIG. 16, a very good reciprocal relationship is shown, and it can be seen that a poorly sealed place can be detected with extremely high sensitivity.
Some sealants are not necessarily suitable for sprayed ceramics.
The above inspection method means a new quantitative evaluation method that replaces the semi-quantitative evaluation method that evaluates by the number of spots. Become a research tool.

In each of the above inspections, an apparatus using the apparatus shown in FIG. 1 was shown. On the other hand, when the sub probe 3 is provided in the scanning unit 10 together with the probes 1 and 2 for peeling test, the positional relationship of the sub probe 3 with respect to the probes 1 and 3 for peeling test is shown in FIG. It is not limited to what is shown. For example, it may be provided behind the probe 1 of the transmission unit, or may be provided in front of the probe 1 of the reception unit.
In the above embodiment, the probe 2 of the receiving unit is arranged in front of the probe 1 of the transmitting unit in the scanning direction, but the front and rear of both probes 1 and 2 may be reversed. Can be implemented.
In the above embodiment, the probes 1 to 3 are arranged along the scanning direction of the scanning unit 10 (the direction of rolling by the casters 7... 7), but intersect the scanning direction. Even those arranged in a direction can be implemented.

  In each of the above implementations, the thermal spray coating M is a single layer, and the peeling of the interface between the thermal spray coating M and the substrate N is inspected. In addition, the thermal spray coating M is assumed to be composed of a plurality of thermal spray layers, and can be implemented as a method for examining the delamination.

  As described above, the invention of the present application is a novel one that non-destructive inspection is performed using airborne ultrasonic waves for peeling and sealing of the thermal spray coating. Of these, it is an epoch-making thing that makes it possible to inspect the peeling reliably by examining surface waves.

1 is a schematic side view of an inspection apparatus according to an embodiment of the present invention, and is a cross-sectional view of a scanning unit. (A) is explanatory drawing which looked at the principal part of FIG. 1 from the side, (B) is explanatory drawing of a surface wave. It is a schematic side view which shows the use condition of the inspection apparatus of FIG. It is a schematic side view which shows other embodiment of a scanning part. It is explanatory drawing which shows the scanning position of the peeling test | inspection with respect to the sample which has peeling which was performed using this apparatus. It is explanatory drawing which shows the test result of the said sample. It is explanatory drawing which shows the relationship between the amplitude of the ultrasonic wave received in the said test, and a scanning position. It is explanatory drawing which shows the relationship between the amplitude of the ultrasonic wave received in the peeling test | inspection performed about the sample different from FIG. 6, and a scanning position. (A) is explanatory drawing which shows the microscope image of the sample which has the said peeling, (B) is explanatory drawing which shows the microscope image of the healthy sample without peeling. It is explanatory drawing which shows the test | inspection position of the sealing test performed using the said apparatus. (A) is explanatory drawing which shows the relationship between the amplitude of an ultrasonic wave and the time about the void | hole which is not made | formed about an aluminum sprayed coating about a ferroxyl test, and (B) is made sealing appropriately about an aluminum sprayed coating. It is explanatory drawing which shows the relationship between the amplitude of an ultrasonic wave, and time about what is. (A) is explanatory drawing which shows the relationship of the amplitude and time of the ultrasonic wave about the void | hole which is not made | formed with respect to a ceramic sprayed coating, (B) is what is made to seal appropriately about a ceramic sprayed coating It is explanatory drawing which shows the relationship between the amplitude of the ultrasonic wave, and time. It is explanatory drawing which shows the relationship between the amplitude of the received ultrasonic wave, and a scanning position about the aluminum sprayed coating shown in FIG. It is explanatory drawing which shows the relationship between the amplitude of the received ultrasonic wave, and a scanning position about the ceramic sprayed coating shown in FIG. (A) is explanatory drawing which shows the result of a ferroxyl test about the thing in which sealing is not made appropriately about a ceramic sprayed coating, (B) is a thing of a ferroxyl test about what is well sealed about a ceramic sprayed coating. It is explanatory drawing which shows a result. It is explanatory drawing of the graph which shows the relationship between the reflected ultrasonic intensity in the said ceramic sprayed coating, and the blue spot by a ferroxyl test.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Probe (of transmission part) 2 Probe (of reception part) 3 Sub probe 4 Transmission side holding part 5 Reception side holding part 6 Sub holding part 7 Caster

Claims (8)

This is a thermal spray coating inspection method for examining the peeling at the interface between the thermal spray coating and the substrate or the peeling at the interface between the thermal spray layers for a thermal spray coating having at least one thermal spray layer covering the substrate. And
Using a transmitter that emits ultrasonic waves toward the thermal spray coating and a receiver that receives ultrasonic waves from the thermal spray coating,
The transmitter is equipped with an aerial ultrasonic probe that propagates ultrasonic waves into the air and enters the thermal spray coating, and the receiver receives ultrasonic waves propagating from the thermal spray coating into the air. Receiving, equipped with an aerial ultrasonic probe, respectively,
Both the transmitter and the receiver are placed above the thermal spray coating,
Point the probe of the transmitter at an angle to the surface of the thermal spray coating,
In a state in which the film surface of the thermal spray coating is viewed in plan, the probe of the receiving unit is arranged on an extension line of the direction of the probe of the transmitting unit,
The ultrasonic wave is incident on the thermal spray coating from the probe of the transmission unit, the surface wave is propagated in the thermal spray coating, and the strength of the surface wave received by the probe of the reception unit is not separated. A method for inspecting a sprayed coating, characterized by examining the presence or absence of peeling by comparing with the strength of surface waves in the case. The above-mentioned surface wave travels in the direction along the interface while performing multiple reflections between the interface for examining peeling and the surface of the thermal spray coating.
2. The thermal spray coating inspection method according to claim 1, wherein a surface wave after reflection noise attenuation generated on the surface of the thermal spray coating upon incidence is examined. The probe of the receiver receives surface waves that leak from the surface of the thermal spray coating,
3. The thermal spray coating inspection method according to claim 1, wherein the distance between the probe of the transmitter and the probe of the receiver is at least four times the thickness of the thermal spray coating. Both probes of the air ultrasonic wave are provided with a vibration part that oscillates when voltage is applied and generates an ultrasonic wave, and an acoustic matching member, and the acoustic matching member is provided in the vibration part, so that the vibration part and the air By suppressing the difference in acoustic impedance, it is possible to propagate ultrasonic waves into the air,
The distance between the probe of the transmitter and the probe of the receiver, and the distance between each probe of the transmitter and receiver and the surface of the thermal spray coating are separated by the attenuation of the ultrasonic wave being propagated. Is within a range that does not become impossible,
In the state viewed from the side, the probe of the transmitting unit forms an angle of 30 degrees or more and 89.5 degrees or less with respect to the interface to be inspected, and the direction of the probe of the receiving unit is viewed from the side. A line perpendicular to the film surface of the thermal spray coating at an intermediate point between the two probes in a state is substantially line symmetric with the direction of the probe of the transmitting unit. 4. The thermal spray coating inspection method according to any one of 1 to 3. This is a thermal spray coating inspection device that examines the thermal spray coating provided with at least one thermal spray layer covering the substrate, for peeling at the interface between the thermal spray coating and the substrate, or for peeling at the interface between the thermal spray layers. And
A transmitter that emits ultrasonic waves toward the thermal spray coating, and a receiver that receives the ultrasonic waves from the thermal spray coating,
The transmitter is equipped with an aerial ultrasonic probe that propagates the ultrasonic wave into the air and enters it into the thermal spray coating.
The receiver is equipped with an aerial ultrasonic probe that receives ultrasonic waves propagating in the air from the thermal spray coating,
Point the probe of the transmitter at an angle to the surface of the thermal spray coating,
In a plan view, the probe of the receiving unit is arranged at a distance from the probe of the transmitting unit at the tip of the probe of the transmitting unit,
The distance between the probe of the transmitter and the probe of the receiver is at least three times the thickness of the thermal spray coating,
The ultrasonic wave is incident on the thermal spray coating from the probe of the transmission unit to generate a surface wave in the thermal spray coating, and the strength of the surface wave received by the probe of the reception unit is not separated. An apparatus for inspecting a sprayed coating characterized by examining the presence or absence of delamination by comparing with the strength of surface wave in the case. The base material is metal or ceramic, and the thermal spray coating is formed by thermal spraying of metal, polymer, ceramic or cermet,
The vibration frequency of each probe is 200 to 800 kHz,
A scanning unit that holds both the probe of the transmission unit and the reception unit, and that can scan both probes along the surface of the thermal spray coating,
The scanning unit is to hold the probes of the transmission unit and the reception unit to be at least three times the thickness of the thermal spray coating and to take an interval of 200 mm or less,
Furthermore, the scanning unit holds each probe with an interval of 5 mm or more and 80 mm or less from the surface of the thermal spray coating,
6. The thermal spray coating inspection apparatus according to claim 5, wherein peeling is detected at the interface based on a change in intensity of the received surface wave during scanning. The scanning unit is mainly formed of a transparent material, and includes at least a transmission side holding unit that holds the probe of the transmission unit, a reception side holding unit that holds the probe of the reception unit, and at least a front wheel and a rear wheel. With two casters, the probe can be scanned along the film surface of the thermal spray coating by holding it by hand and making the caster follow the surface of the thermal spray coating. Yes,
Both casters have at least a surface formed of Teflon (registered trademark) resin,
The transmission side holding unit holds the probe of the transmission unit at an angle of 30 degrees or more and 89.5 degrees or less with respect to a lower end line connecting the lower ends of both casters. In view, about the perpendicular perpendicular to the lower end line, hold the probe of the reception unit so as to face the direction of line symmetry with the direction of the probe of the transmission unit,
Further, the transmitting side holding unit and the receiving side holding unit hold each of the probes with an interval of 5 mm or more and 50 mm or less upward from the lower end line in the vertical direction. The thermal spray coating inspection apparatus according to claim 6. A sub-transmission unit that emits ultrasonic waves toward the thermal spray coating, and a sub-reception unit that receives ultrasonic waves from the thermal spray coating,
The sub-transmission unit includes an aerial ultrasonic probe that propagates ultrasonic waves into the air and enters the thermal spray coating.
The sub-reception unit has an aerial ultrasonic probe that receives ultrasonic waves propagating from the thermal spray coating in the air,
Both the sub-transmitter and sub-receiver probes are arranged above the thermal spray coating,
The direction of the probe of the sub-transmission unit is substantially perpendicular to the film surface of the thermal spray coating,
The sub-transmitter probe emits ultrasonic waves in the air toward the thermal spray coating, and the sub-receiver probe receives the ultrasonic waves returning from the thermal spray coating to seal the thermal spray coating. 8. The thermal spray coating inspection apparatus according to claim 5, wherein a state of the hole treatment is detected.

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