JP2007297947A - Fluorescence spectroscopic internal stress inspection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an integrity evaluation device for heat insulating coating applied on a present gas turbine or the like. <P>SOLUTION: This device is provided with a bore scope tube 11 provided with an optical fiber transmitting irradiation light and a lens relay transmitting images, a fluorescence excitation visible laser generation device 21, a tunable filter 32, a two dimensional CCD camera 31 and an arithmetic unit 41. A fluorescence excitation visible laser is irradiated to an object from a tip of the bore scope tube 11. Fluorescence emitted from the object is detected by the two dimensional CCD camera 31 through the lens relay via the tunable filter 32. A peak of fluorescence spectrum is detected by the arithmetic unit 41 based on camera output and transmitted light frequency of the tunable filter and existence of detachment is determined by using a relation between peak wavelength transition and internal stress. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a thermal barrier coating applied to high-temperature combustion equipment such as aero engines and industrial gas turbines, and more particularly to a ceramic thermal barrier coating (TBC) that covers the surfaces of rotor blades, stationary blades, and combustor liners in turbine parts. The present invention relates to an apparatus for inspecting the soundness of a machine.

Gas turbines used in aircraft, ships, power generation devices, and the like are designed to increase the gas turbine operating temperature (combustion gas turbine inlet temperature) for higher efficiency and higher output. In order to raise the turbine operating temperature, a cooling technique and a thermal barrier coating technique that protect components such as turbine blades, stationary blades, and combustors that are exposed to high-temperature combustion gas are required.
Furthermore, in order to maintain a safe and secure society, it is required to ensure the safety of aircraft gas turbines and guarantee the life of power generation gas turbines. Further, from the viewpoint of reducing running costs, it is an important issue to improve the durability of gas turbine components, and further improvements in heat shielding performance and durability are required for the heat shielding coating.

Thermal barrier coatings (TBC) often used in gas turbines are generally made of MCrAlY (M) on a superheat-resistant alloy base material mainly composed of nickel (Ni), cobalt (Co), iron (Fe) and the like. Is a metal undercoat by applying a metal bond coat of one or more of nickel, cobalt, and iron), and a ceramic heat shield layer is formed on the metal undercoat. It is a coating.
The ceramic thermal barrier layer is formed of a low thermal conductive ceramic such as zirconium oxide (ZrO ₂ ) partially stabilized with yttrium oxide (Y ₂ O ₃ ).
The metal bond coat adheres to the metal substrate and has a corrosion resistance / oxidation resistance metal coating function to prevent peeling.

However, these thermal barrier coatings have a metal underlayer and ceramic thermal barrier layer when used for a long time due to high temperature corrosion (oxidation) due to exposure to a high temperature environment during operation of the gas turbine and thermal fatigue due to repeated start and stop. Peeling damage between.
Peeling due to high-temperature oxidation is caused by the fact that aluminum contained in the metal underlayer reacts with oxygen supplied from the ceramic heat shield layer, and an oxide layer (TGO) containing alumina (Al ₂ O ₃ ) grows on the surface of the metal underlayer. It is presumed that the thermal stress acting on the ceramic heat shield layer increases as the oxide layer becomes thicker and eventually the ceramic heat shield layer is peeled off.

  The thermal barrier ceramic layer has a thermal expansion coefficient that is significantly different from that of the metal substrate, so that thermal stress is generated and peeling is likely to occur at the interface. In addition, the heat-shielding ceramic layer has many pores and supplies oxygen entering from the outside and oxygen dissociated at high temperature to the lower layer, so that an oxide layer of nickel, cobalt, aluminum, etc. at the interface with the MCrAlY alloy layer The MCrAlY alloy layer cannot be depleted or damaged, and further, oxidation or strength reduction of the metal substrate cannot be suppressed.

The current thermal barrier coating has an effect of suppressing the temperature rise of the member by about 20 to 100 ° C., but the presence or absence of peeling damage of the thermal barrier coating greatly affects the deterioration of the substrate. Therefore, it is desired to develop a technique for evaluating the soundness of the thermal barrier coating of the gas turbine member in a non-destructive manner and performing recoating according to the degree of damage.
In other words, if a device that can observe an event that reflects the situation near the interface of the thermal barrier coating or a device that directly detects the stress state of the TGO that is the crack occurrence site is obtained, the soundness of the thermal barrier coating is reduced. It becomes possible to evaluate by destruction, and the remaining life of the thermal barrier coating can be evaluated.

At present, the soundness confirmation method implemented for the thermal barrier coating of the current gas turbine is to insert a borescope or the like into the casing and observe the appearance. The appearance observation by the appearance damage evaluation apparatus can evaluate surface damage such as indentation due to non-combustible material, but cannot obtain information on internal damage of the thermal barrier coating.
Therefore, it is possible to evaluate the peeling damage of the thermal barrier coating, but it is impossible to evaluate the remaining life of the thermal barrier coating that does not lead to peeling.

Patent Document 1 discloses a thermal stress generated in a ceramic layer by non-destructively detecting an oxide layer generated between a ceramic layer and a corrosion-resistant alloy layer and estimating the amount of the oxide layer by imaging processing. A ceramic coating remaining life evaluation diagnostic system that calculates the cumulative damage degree and evaluates the remaining life of the ceramic layer and the corrosion-resistant alloy layer is disclosed.
Here, as the nondestructive detection device, a method using ultrasonic waves, a method using X-ray transmission, and a method using an infrared camera are employed. However, each of these methods is based on the measurement conditions, and the non-measurement body is limited to parts that can be removed from the actual machine or relatively small parts whose shape is not complicated, or in the infrared camera method, heating is performed from the back side of the non-measurement body. Therefore, there is a problem that it is limited to a member that can be heated because it is estimated from the temperature difference appearing on the surface.

In addition, in Patent Document 2, in view of the uncertainty of visual evaluation, after visual inspection, the internal peeling of the thermal barrier coating is inspected by an infrared thermography method, and as a result, a peeling pattern is detected, Disclosed is a thermal barrier coating deterioration diagnosis method that performs surface element analysis inspection by fluorescent X-ray method and film thickness measurement using eddy current flaw detection to detect deterioration by detecting the presence or absence of delamination and wear of the thermal barrier coating, etc. ing.
According to the disclosed method, a part detected by an infrared thermography method is detected by using a surface element analysis method to detect a mere scale or the like, thereby confirming a peeled part. By means of a composite measurement method, it is possible to indirectly detect the target thermal barrier coating peeling phenomenon.

The stress of TGO generated between the ceramic heat shield layer and the metal underlayer has a high value of about 1 to 3 GPa when healthy, and is released and lowered when peeled off. Therefore, there is a method for evaluating the deterioration of the thermal barrier coating by measuring the stress of the ceramic thermal barrier layer or TGO using a laser Raman method, a photoluminescence method, an X-ray diffraction method or the like.
In particular, a photoluminescence method for measuring TGO stress by irradiating a sample with a visible light laser and detecting a spectrum of fluorescence excited by TGO is effective. According to this method, the laser light for exciting the fluorescence passes through the outermost zirconia ceramic heat shield layer of about 0.5 mm and reaches the oxide layer, so that the stress of the oxide layer is measured nondestructively. be able to.

  In Patent Document 3, a soundness evaluation apparatus using a photoluminescence method is used to analyze a radiation spectrum by capturing fluorescence generated by irradiating an ultraviolet laser to a TBC containing a rare earth element as a fluorescent material with a detector. An apparatus capable of estimating the cumulative damage degree and the remaining life by calculating the amount of the crystal phase is disclosed. The disclosed method is based on the fact that the intensity ratio of a certain peak of fluorescence, for example, the ratio of the intensity of the peak at 605 nm to the peak at 615 nm, is related to the amount of monoclinic TBC. The remaining life is calculated.

Furthermore, as a method of judging the deterioration state of the ceramic thermal barrier layer from the measured stress value of TGO, a method of comparing with a value estimated by the finite element method, exposure to a predetermined high-temperature oxidation environment, thermal cycle or heat By measuring the residual stress of TGO for a member that has caused deterioration due to impact, a method of grasping and contrasting the correlation between the deterioration state and the residual stress in advance can be used.
The photoluminescence method uses a microscope configuration, for example, irradiates a sample with a green laser having a wavelength of 532 nm through an objective lens, separates the generated fluorescence with a spectroscope, and picks up an image with a CCD camera. To evaluate the stress.

In the current photoluminescence method, the sample is limited to a small flat plate, so even if it is expected as a TBC soundness evaluation method, a thermal barrier coating coated on a turbine blade, stationary blade, or combustor with a complicated shape Can not be used as a means to evaluate as it is.
In addition, since the sample is irradiated with the visible light laser by squeezing the visible light laser, the measurement area has a very small diameter of about 15 μm, and it takes a very long measurement time to measure the entire surface of the thermal barrier coating of the gas turbine member. Is necessary and practically difficult.
Furthermore, it cannot be used as a means for evaluating the remaining life by measuring the current gas turbine in operation as it is.

It is known that when a green laser with a wavelength of 514 nm is irradiated, fluorescence generated by Cr ³⁺ contained in TGO causes a frequency transition corresponding to the stress of TGO.
Non-Patent Document 1 uses this phenomenon to confirm that there is a clear difference in fluorescence wavelength between stress-free sapphire and stressed TGO, and uses it for quality control of TBC through non-destructive measurement. Discussing the possibilities.
However, the trial measuring device is a probe in which a probe using an optical fiber is connected to a laboratory Raman measuring device, and cannot be applied without disassembling an actual machine.
JP-A-11-148931 JP 2004-156444 A US Pat. No. 6,730,918 Maurice Gell, et al., “Photoluminescence Piezospectroscopy: A Multi-Purpose Quality Control and NDI Technique for Thermal Barrier Coatings” Int. J. Applied Ceramic Technology, 1 [4] 316-29 (2004)

  The problem to be solved by the present invention is to provide an internal stress inspection apparatus that estimates the internal stress of a material based on the spectral shift of fluorescence, and in particular, a heat shield coated on a complicated shape member such as a current gas turbine. It is to provide an apparatus that can evaluate the soundness of a coating. Furthermore, it is to provide a soundness evaluation device that can inspect the internal damage of the thermal barrier coating without opening the current gas turbine, and also enables the thermal barrier coating to be inspected while the current gas turbine is in operation. It is to provide a soundness evaluation device. It is another object of the present invention to provide a combined functional damage evaluation apparatus capable of simultaneously inspecting the surface state and internal damage of a thermal barrier coating.

  In order to solve the above problems, a fluorescence spectroscopy internal stress inspection apparatus according to the present invention includes a borescope tube including an optical fiber that transmits irradiation light and a lens relay that transmits an image, a visible light laser generator for fluorescence excitation, and An image output device that outputs a light intensity signal for each wavelength component for each pixel on the fluorescence image, and an arithmetic unit composed of an electronic computer, and the laser generated by the visible light laser generator for excitation of fluorescence is emitted from the borescope tube. The target is irradiated through the fiber, the fluorescence emitted from the target is detected by the image output device through the lens relay, and the peak of the optical frequency spectrum is detected based on the output of the image output device in the arithmetic unit, and the magnitude of the internal stress It is characterized by determining.

The image output apparatus includes a tunable filter and a two-dimensional CCD camera, and further includes a camera controller that controls the CCD camera and a filter controller that adjusts the transmitted light frequency of the tunable filter, and is emitted from an object. The fluorescence may be detected by a two-dimensional CCD camera through a lens relay and a tunable filter. The arithmetic unit detects the peak wavelength of the optical frequency spectrum of fluorescence based on the optical signal detected by the camera and the transmitted optical frequency of the tunable filter obtained from the filter controller, and determines the magnitude of the internal stress of the object. To do.
The image output device also includes a spectroscope, a one-dimensional CCD camera, and a camera controller that controls the CCD camera, and detects the fluorescence emitted from the object through the lens relay and the spectroscope through the spectroscope. You may do. The arithmetic unit can estimate the peak position of the optical frequency spectrum of the fluorescence based on the camera signal that has detected the light transmitted through the spectroscope and the transmitted light frequency of the spectroscope.

The inspection object is an object including a material that generates fluorescence when excited by visible light, and a peak position in the fluorescence spectrum is related to internal stress. In particular, it is a thermal barrier coating that has a structure in which a metal bonding layer, which is a metal underlayer, and a ceramic thermal barrier layer are stacked in this order on a superalloy substrate, and the metal underlayer includes a fluorescent material that generates fluorescence by a visible light laser. Preferably there is.
In such a thermal barrier coating, an oxide layer (TGO) in which the material of the metal underlayer is oxidized by oxygen infiltrated from the ceramic thermal barrier layer grows, and this oxide layer causes the ceramic layer finally. A phenomenon occurs in which the heat shielding layer peels off. In the soundness inspection apparatus of the present invention, the visible light laser for fluorescence excitation passes through the thin ceramic heat shield layer and reaches the TGO, and the internal stress is estimated based on the transition of the fluorescence frequency generated by the fluorescent material contained in the TGO. Therefore, the peeling of the ceramic heat shield layer can be determined in a non-contact manner.

Since both the excitation laser and the fluorescence are visible light, the same borescope tube as that used in a commercially available borescope can be used. Further, a light source for illumination and an eyepiece may be provided to the borescope tube so as to be shared with the borescope, and surface observation and internal stress observation may be performed simultaneously or by switching as necessary.
Because the tube with the same structure as the borescope is used, even if you want to measure thermal barrier coatings that protect parts such as moving blades, stationary blades, and combustors of gas turbines, A tube-like probe can be inserted through the viewing hole for inspection.
Tunable filters are filters that can electrically adjust the frequency of transmitted light. For example, liquid crystal tunable filters that use the characteristics of liquid crystals (VariSpec (trade name, manufactured by Cambridge Research and Instrumentation)) are commercially available. You can also use what is being done.

Furthermore, an eddy current film thickness meter or an AC impedance film thickness meter is provided, and the thickness of the ceramic heat shield layer and the thickness of the metal bonding layer are simultaneously measured and taken into account. By observing from the viewpoint, the soundness and remaining life of the thermal barrier coating can be more accurately evaluated.
In addition, by measuring the fluorescence generated by laser irradiation with a pulse synchronized with the appearance time interval of the moving blade while rotating the turbine etc., the internal stress distribution according to the surface position is measured by looking at the moving blade as a group. can do.

By using the fluorescent spectroscopic internal stress inspection apparatus of the present invention, the state of the inner layer of the thermal barrier coating such as a turbine rotor blade, stationary blade, combustor, etc. without being disassembled using the same thing as the probe tube of the borescope Can detect the exfoliation of the ceramic thermal barrier layer and estimate the remaining life, so it is possible to accurately recoat thermal barrier coatings applied to high-temperature combustion equipment such as aircraft engines and industrial gas turbines. To provide more information and to perform more advanced maintenance.
The fluorescence spectroscopic internal stress inspection apparatus of the present invention is not limited to a thermal barrier coating, and generates fluorescence in the visible light region when irradiated with a visible light laser, and the wavelength of the fluorescence is affected by internal stress. Needless to say, the present invention can be similarly applied to other materials.

Hereinafter, the best mode of a fluorescence spectroscopy internal stress inspection apparatus of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional view schematically showing the configuration of a fluorescence spectroscopy internal stress inspection apparatus according to an embodiment of the present invention, FIG. 2 is a drawing showing stress transition of fluorescence, and FIG. 3 is obtained by a two-dimensional CCD camera. FIG. 4 is a block diagram for explaining the procedure of peeling determination, FIGS. 5 and 6 are diagrams for explaining an example of measuring a moving blade by a fluorescence spectroscopic internal stress inspection apparatus, and FIG. Drawing which shows the example of an observation of the internal stress of the fluorescence spectroscopy type | mold internal stress exposed to high temperature for a long time, FIG. 8 is a conceptual diagram of the turbine blade automatic inspection apparatus comprised with a fluorescence spectroscopy type internal stress inspection apparatus.

The fluorescence spectroscopic internal stress inspection apparatus of the present embodiment includes a borescope tube 11, a fluorescence excitation laser generator 21, a two-dimensional CCD camera 31, a calculation device 41, and an eyepiece 51.
The borescope tube 11 is a stainless steel tube in which a lens relay that transmits an image is provided along the central axis, and an optical fiber bundle that transmits laser light is disposed outside the lens relay, similar to a borescope tube that is an industrial endoscope. It is coated with.

The output laser of the fluorescence excitation laser generator 21 is incident on the borescope tube 11 through the optical fiber 12 via the optical fiber 22, the optical path switching mirror 23, and the transflective plate 24. An object is irradiated as excitation light 13 from the end face.
The target object includes a fluorescent substance that generates fluorescence by a fluorescence excitation laser, and when an excitation light beam 13 is received, fluorescence 14 having a specific wavelength is generated.

For example, chromium ions (Cr ³⁺ ) contained in an oxide film (TGO) of a thermal barrier coating (TBC) receive R1 (wave number 14402 cm ⁻¹ ) and R2 (14432 cm) in a stress-free state when subjected to a green laser having a wavelength of 514 nm. ^-1 ) fluorescence can be excited. As shown in FIG. 2, since the peak wave value of this fluorescence changes due to the stress, the stress can be estimated by the change in the wavelength of the peak. The R2 peak changes more accurately with respect to the stress change.

FIG. 2 is a drawing schematically showing an example of the wave number distribution of fluorescence of chromium ions. The fluorescence peak of TGO constrained in the thermal barrier coating transitions to the smaller wave number with respect to the fluorescence peak of unstressed aluminum oxide (sapphire). The transition amount Δν is proportional to the stress σ,
Δν = Πσ (Formula 1)
It is known that Π is a proportional coefficient.

Therefore, the green laser generator is used as the fluorescence excitation laser generator 21. Since the green laser is in the visible light region, it penetrates the optical fiber bundle of the borescope tube 11 as well as the illumination light of the borescope.
The image signal of the object is transmitted by a lens relay incorporated in the borescope tube 11, passes through the transflective reflector 24, and enters the two-dimensional CCD camera 31. The image signal received by the two-dimensional CCD camera 31 includes fluorescence emitted from the object.
When observing fluorescence, the second optical path switching mirror 25 is retracted to a position avoiding the optical path.

At the entrance of the two-dimensional CCD camera 31, a tunable filter 32 having a narrow light transmission region and having a variable center wavelength is provided, and the wavelength of the transmitted light is changed at every predetermined interval to scan the CCD camera 31. The wavelength of incident light can be selected sequentially.
Therefore, the two-dimensional CCD camera 31 combined with the tunable filter 32 performs the same operation as that of the spectrum analysis, and provides a two-dimensional image for each wavelength selected by the filter.

  The tunable filter 32 is preferably a liquid crystal variable filter such as a liquid crystal tunable filter LCTF (VariSpec (trade name) manufactured by Cambridge Research and Instrumentation) utilizing the characteristics of liquid crystal. Varispec (trade name) is a unit in which a plurality of units in which a phase retardation plate and a liquid crystal cell are sandwiched between a pair of linear polarizers are arranged in series, and the bandwidth of transmitted light is adjusted to be extremely narrow. It is a filter that can adjust the frequency electrically, and achieves a bandwidth of about 0.25 nm in the region of 500-720 nm.

A filter controller 34 is attached to the tunable filter 32, and the filter controller 34 adjusts the transmitted light center frequency and transmits the frequency to the arithmetic unit 41.
A camera controller 33 is attached to the two-dimensional CCD camera 31. The camera controller 33 controls the camera 31 to acquire an image and transmits the output of the camera to the arithmetic unit 41. Since the two-dimensional CCD camera 31 captures an image transmitted through the tunable filter 32, it acquires and outputs an image cut out for each transmission frequency of the filter.
One screen of the two-dimensional CCD camera 31 corresponds to 40 μm square on the surface of the object. In the conventional microscopic photoluminescence method, the measurement area is greatly enlarged as compared with observation in a measurement area having a diameter of about 15 μm, and the efficiency is greatly improved even when the same surface area is measured.

  In addition, the halogen lamp 52 is turned on by switching the first optical path switching mirror 23 and the second optical path switching mirror 25. Then, the light from the halogen lamp 52 enters the optical fiber bundle of the borescope tube 11 and illuminates the object. The illuminated image of the surface of the object is transmitted through the lens relay, transmitted through the transflective reflector 24, reflected by the second optical path switching mirror 25 that has advanced into the optical path, and observed with the naked eye from the eyepiece 51. become able to. In this way, the fluorescence spectroscopic internal stress inspection apparatus can be used as a borescope. Note that a CCD camera may be set on the eyepiece 51, and an image signal may be transmitted to the arithmetic unit 41 for image processing.

The computing device 41 detects the internal stress of the measurement object using the camera output and the transmitted light frequency information from the filter controller, and evaluates the soundness more quantitatively.
FIG. 3 is a graph in which a light intensity signal obtained from a predetermined pixel in the two-dimensional CCD camera 31 is plotted with respect to wavelength and wave number.
The upper graph (a) shows the light intensity when measured by irradiating a green laser with a wavelength of 532 nm on alumina in a state without internal stress, and the lower graph (b) shows the oxide layer generated in the thermal barrier coating. It is a measured value of the light intensity at the time. Since the filter transmission frequency is a light intensity signal acquired from the image signal when the filter transmission frequency is sequentially set electrically at predetermined intervals, the measurement value is obtained for each frequency having a discrete value.

The graph clearly shows that the R1 peak and the R2 peak exist, and the wavelength λ transitions to a longer one in the stress state than in the no-stress state. As described above, the internal stress of TGO can be estimated by using the wavelength transition amount Δλ2 of the R2 peak. However, since the measurement data is obtained as discrete numerical values, the peak cannot be obtained directly from the graph. Further, since the two peaks overlap, the peak values are interfered with each other and deviate from the peaks on the graph.
Therefore, in order to know the correct internal stress value, it is necessary to obtain an accurate peak position, and a method capable of accurately estimating the position of the mutually interfered peak using this discrete information is required.

By fitting the peak positions of R1 and R2 to two bell-shaped distribution function curves, accurate values can be obtained. In general, a Gaussian function (G (ν−ν0; w)) and a Lorentz function (L (ν−ν0; w)) are used as this distribution function. Does not fit. However, from experience in the nano-stress microscope, it is known that fitting can be performed with high accuracy by using the pseudo-Fockt function PV shown below.
PV (ν−ν0) = G (ν−ν0; w1) [L (ν−ν0; w2)] ^β
(Formula 2)
Here, G is a Gaussian distribution function related to the width w1, L is a Lorentz distribution function related to the width w2, and the index β is a positive constant.

The internal stress of the TGO in the image is calculated from the wavelength or wave number at the peak obtained as a result of such spectrum analysis.
The internal stress of TGO shows a compressive stress of about 2 to 2.3 GPa when the TGO layer is thin and there is no interfacial delamination with the base material, and when the thickness is slightly increased, interfacial cracks are generated and 1.5 to 1 Then, the internal stress is further reduced as the interfacial peeling progresses, and when the metal underlayer and the ceramic heat shield layer are completely peeled, the internal stress is released and becomes almost 0 MPa.

Therefore, the state of peeling damage between the metal underlayer and the ceramic heat shield layer is estimated by measuring the internal stress.
FIG. 4 is a block diagram for explaining a procedure of peeling determination executed in the arithmetic device 41.
The tip of the borescope tube 11 is directed toward the surface of the measurement object, and a green laser is irradiated. The generated fluorescence is received by the two-dimensional CCD camera 31.
The arithmetic unit 41 acquires the CCD camera output (101) from the camera controller 33, acquires the wavelength information (102) of the transmitted light from the filter controller 34, and performs the spectrum analysis (103).

In the spectrum analysis, the fluorescence spectrum of the object surface corresponding to each pixel of the CCD camera 31 is generated from the result of changing the transmitted light wavelength in a predetermined wavelength range. Peak fitting is performed on the generated fluorescence spectrum, the peak position is accurately estimated, and the wavelength shift (Δλ) from the peak position in the unstressed state is calculated.
Using the calculated wavelength shift, the internal stress value is estimated based on the previous relational expression (Formula 1) that indicates that the wave number deviation and the internal stress are proportional (104).
The presence or absence of peeling is determined from the estimated value of internal stress (105). The correspondence relationship between the internal stress and the peeled state can be investigated in advance and used as a criterion (106) for determining the presence or absence of peeling. In addition, it is preferable to improve the accuracy of determination in consideration of the result (107) of surface observation by the borescope.

If the fluorescence spectroscopic internal stress inspection apparatus of the present embodiment is used, the borescope tube 11 is inserted through the observation hole 63 provided in the cover 62 of the aircraft engine 60 as shown in FIGS. The internal stress can be measured and the peeled state can be observed while the thermal barrier coating coated on the surface of 61 is housed inside the engine.
The peeled state is estimated based on the internal stress obtained based on the fluorescence of chromium ions contained in the oxide layer of the thermal barrier coating by the visible light laser irradiated from the tip of the borescope tube 11.
By adjusting the position of the moving blade 61 and scanning the borescope tube 11 along the surface of the moving blade, the surface of the heat shielding coating on the moving blade can be widely observed.

FIG. 7 is a drawing showing an example in which internal stress was observed for a thermal barrier coating exposed to a high temperature of 1150 ° C. for a long time. In the figure, the lightest part is the region where the internal stress of TGO is -3.5 to -4.5 MPa, the part where the stress is high due to adhesion, and the darkest part is the region of +0.5 to -0.5 MPa. The part is peeled off and the stress is released.
7A shows the stress distribution state when exposed for 10 hours, (b) for 50 hours, (c) for 100 hours, and (d) for 200 hours. It was observed that only a part of the film peeled off after a short exposure, but peeled off almost over the entire surface.

Moreover, as shown in FIG. 8, the turbine blade automatic inspection device can be configured by combining the fluorescence spectroscopy internal stress inspection device 70, the sample driving device 71, and the automatic conveyance device 72 of this embodiment.
The sample driving device 71 holds the turbine blade in a predetermined position and orientation with respect to the fluorescence spectroscopy internal stress inspection device 70, and drives the turbine blade according to the program to automatically set the inspection target portion of the turbine blade 73 inside the fluorescence spectroscopy method. Apply to stress testing equipment. The fluorescence spectroscopic internal stress inspection apparatus analyzes the spectrum of the fluorescence excited by the visible light laser to determine the position of the R2 peak, calculates the internal stress, and estimates the peeling state. When the measurement is completed for one turbine blade, the turbine blade that has been inspected is discharged by the automatic conveyance device, and the next turbine blade is supplied to the sample driving device to perform automatic inspection one after another.

  In addition, blinking the excitation laser at an interval synchronized with the interval between the rotating blades and observing it with a CCD camera to observe the average peel-off state of the thermal barrier coating at the same site for the rotating blades Can do.

In addition, the fluorescence spectroscopic internal stress inspection apparatus according to the present embodiment is provided with an appearance damage inspection apparatus such as a borescope, and further, an eddy current type film thickness measuring device capable of measuring the thickness of the ceramic thermal barrier layer, a metal bonding layer By providing an AC impedance meter or the like that can measure the thickness of the film and making it a multiple function, it is possible to configure a device that realizes more advanced damage evaluation.
TBC peeling or collision marks such as metal powder can be found by TBC appearance inspection performed in the borescope, and the internal state of the TBC can be estimated by fluorescence detection of a fluorescence spectroscopic internal stress inspection apparatus. However, with this alone, when the TBC film thickness is thin, the TGO stress is evaluated to be small, and it is difficult to properly evaluate the soundness of the TBC.
On the other hand, by taking into account the results of simultaneously measuring the thickness of the TBC and the thickness of the metal bonding layer, it is possible to evaluate the soundness and remaining life of the TBC with high reliability.

The porosity changes with the sintering of the ceramic thermal barrier layer. However, if the porosity is different, the transmittance of the fluorescence generated by TGO changes. Therefore, by observing the change in luminance from the fluorescence spectrum, the ceramic barrier is observed. The sinterability of the heat layer can be evaluated.
Moreover, since the temperature level at which the thermal barrier coating has a history similarly affects the peak luminance of the fluorescence spectrum, it is possible to estimate the exposure temperature history by the photoluminescence method using the fluorescence spectroscopy internal stress inspection apparatus of this embodiment. it can.
As described above, various internal damage inspections can be performed by using the fluorescence spectroscopic internal stress inspection apparatus according to the present embodiment.

The fluorescence spectroscopic internal stress inspection apparatus of the present embodiment is mainly composed of a high-temperature combustion device such as an aero engine or an industrial gas turbine, in particular, a thermal barrier coating applied to a moving blade, a stationary blade or a combustor liner of the turbine portion. The purpose is to check the soundness of TBC).
By using the fluorescence spectroscopic internal stress inspection apparatus of this embodiment, a wider range of measurement is possible than with the conventional photoluminescence method, the inspection efficiency is improved, and the current gas turbine is not opened efficiently and efficiently. Sex assessment is possible.

1 is a structural conceptual diagram of a fluorescence spectroscopy internal stress inspection apparatus according to an embodiment of the present invention. It is drawing which showed typically the example of wave number distribution which shows the stress transition of the fluorescence of the chromium ion in a present Example. It is the graph which plotted the light intensity signal obtained with the two-dimensional CCD camera of a present Example with respect to a wavelength and a wave number. It is a block diagram explaining the procedure of the peeling determination performed in a present Example. It is a conceptual diagram which shows the example which measures a moving blade with the fluorescence spectroscopy type internal stress inspection apparatus of a present Example. It is a perspective view which shows the aircraft engine which is a measuring object in FIG. It is drawing which shows the example which observed the internal stress about the thermal barrier coating exposed to high temperature for a long time. It is a block diagram which shows the turbine blade automatic test | inspection apparatus comprised with the fluorescence spectroscopy type internal stress inspection apparatus of a present Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Borescope tube 12 Optical fiber 13 Excitation light 14 Fluorescence 21 Laser generator for fluorescence excitation 22 Optical fiber 23 Optical path switching mirror 24 Semi-transmission reflector 25 2nd optical path switching mirror 31 Two-dimensional CCD camera 32 Tunable filter 33 Camera controller 34 Filter Controller 41 Arithmetic Unit 51 Eyepiece 52 Halogen Lamp 60 Aero Engine 61 Rotor Blade 62 Cover 63 Observation Hole 70 Fluorescence Spectroscopic Internal Stress Inspection Device 71 Sample Drive Device 72 Automatic Conveyance Device 73 Turbine Blade

Claims (9)

  A borescope tube equipped with an optical fiber that transmits irradiation light and a lens relay that transmits an image, a visible light laser generator for fluorescence excitation, and an image that outputs a light intensity signal for each wavelength component for each pixel on the fluorescence image An output device and an arithmetic device are provided, and the laser generated by the fluorescence excitation visible light laser generator is applied to the object through the optical fiber of the borescope tube, and the fluorescence emitted from the object is emitted. Fluorescence detected by the image output device, and a peak of the optical frequency spectrum of the fluorescence is detected based on an output of the image output device in the arithmetic device to determine the magnitude of internal stress of the object. Spectroscopic internal stress inspection device.   The object has a structure in which a metal bonding layer, which is a metal underlayer, and a ceramic heat shielding layer are sequentially laminated on a superalloy base material, and the metal underlayer includes a shielding material containing a fluorescent substance that generates fluorescence by a visible light laser. 2. The fluorescence spectroscopic internal stress inspection apparatus according to claim 1, wherein the apparatus is a thermal coating. 3. The fluorescence spectroscopy internal stress inspection apparatus according to claim 1, wherein the fluorescence excitation visible light laser is a green laser, and the fluorescent material is chromium ion (Cr ³⁺ ).   4. The fluorescence excitation visible light laser generator generates a pulse laser, and the period of the pulse laser can be adjusted to be synchronized with the rotation of an object. The fluorescence spectroscopic internal stress inspection apparatus as described.   5. The fluorescence spectroscopic internal stress inspection device according to claim 1, wherein a light source for illumination and an eyepiece are provided to the borescope tube to share the borescope tube.   The image output device includes a tunable filter and a two-dimensional CCD camera, and further includes a camera controller that controls the CCD camera and a filter controller that adjusts a transmitted light frequency of the tunable filter, and the object. Fluorescence emitted from the camera is detected by the two-dimensional CCD camera through the lens relay and through the tunable filter, and the arithmetic unit detects the optical signal detected by the camera and the tunable filter acquired from the filter controller. 6. The fluorescence spectroscopy according to claim 1, wherein a peak wavelength of the optical frequency spectrum of the fluorescence is detected on the basis of a transmitted light frequency of the object, and the magnitude of the internal stress of the object is determined. Type internal stress inspection device.   The tunable filter is a filter in which a plurality of sandwiched phase retardation plates and liquid crystal cells sandwiched between a pair of linear polarizers are arranged in series so that the frequency of transmitted light can be adjusted electrically. The fluorescence spectroscopic internal stress inspection apparatus according to claim 6.   The image output device includes a spectroscope, a one-dimensional CCD camera, and a camera controller for controlling the CCD camera, and transmits the fluorescence emitted from the object through the lens relay and the spectroscope through the one-dimensional CCD. Detected by a camera, and the arithmetic unit detects a peak position of the optical frequency spectrum of the fluorescence based on an optical signal transmitted through the spectroscope detected by the camera and a transmitted light frequency of the spectroscope. 6. The fluorescence spectroscopic internal stress inspection apparatus according to claim 1, wherein a magnitude of the internal stress is determined. The fluorescence spectroscopic internal stress inspection apparatus according to any one of claims 1 to 8, further comprising an eddy current film thickness meter or an AC impedance film thickness meter.

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