CN108535212A - A kind of test method of the erosion pattern of the thermal barrier coating based on Terahertz Technology - Google Patents
A kind of test method of the erosion pattern of the thermal barrier coating based on Terahertz Technology Download PDFInfo
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- 239000012720 thermal barrier coating Substances 0.000 title claims abstract description 145
- 230000003628 erosive effect Effects 0.000 title claims abstract description 87
- 238000005516 engineering process Methods 0.000 title claims abstract description 27
- 238000010998 test method Methods 0.000 title claims abstract description 26
- 239000000919 ceramic Substances 0.000 claims abstract description 45
- 238000004611 spectroscopical analysis Methods 0.000 claims abstract description 27
- 238000001328 terahertz time-domain spectroscopy Methods 0.000 claims abstract description 24
- 230000001934 delay Effects 0.000 claims abstract description 10
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- 238000005259 measurement Methods 0.000 claims description 23
- 230000003595 spectral effect Effects 0.000 claims description 12
- 238000000605 extraction Methods 0.000 claims description 3
- 238000001228 spectrum Methods 0.000 claims description 3
- 239000010410 layer Substances 0.000 description 49
- 238000000034 method Methods 0.000 description 13
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- 238000001514 detection method Methods 0.000 description 6
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- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 2
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- 238000009659 non-destructive testing Methods 0.000 description 2
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- G—PHYSICS
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- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
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- G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
- G01N21/3581—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light using far infrared light; using Terahertz radiation
- G01N21/3586—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light using far infrared light; using Terahertz radiation by Terahertz time domain spectroscopy [THz-TDS]
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/88—Investigating the presence of flaws or contamination
- G01N21/95—Investigating the presence of flaws or contamination characterised by the material or shape of the object to be examined
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Abstract
The present invention provides a kind of test method of the erosion pattern of the thermal barrier coating based on Terahertz Technology, emits terahertz pulse to a thermal barrier coating including the use of reflective terahertz time-domain spectroscopy systematic vertical, obtains its time domain spectrogram；Value at the time of triple reflection peak, obtains the time delays at adjacent two peak before being extracted in figure；Frequency domain spectrogram is obtained by doing Fourier transformation to preceding triple reflection peak, calculates the refractive index and thickness of the ceramic layer of the thermal barrier coating；Erosion thermal barrier coating simultaneously scans, and multiple time-domain spectroscopy figures are obtained using time-domain spectroscopy systematic survey；Value at the time of extracting first reflection peak in figure, and make poor, to be thinned according to mathematic interpolation thermal barrier coating thickness with value at the time of first reflection peak above；Obtain the erosion pattern of thermal barrier coating.The test method of the present invention is saved the step of refractive index for measuring thermal barrier coating, and because what is calculated is the thickness that thermal barrier coating is thinned after erosion, is calculated without using the refractive index of thermal barrier coating, to reduce error.
Description
Technical field
The present invention relates to erosion test methods, more particularly relate to a kind of thermal barrier coating erosion shape based on Terahertz Technology
Looks test method.
Background technology
Aero-engine is known as high-end manufacture field " jewel on imperial crown ", with the high speed of aero engine technology
Development, in order to improve the performance and efficiency of engine, the thrust-weight ratio of engine is continuously improved, is fought with U.S.'s first generation to forth generation
For the development course of bucket machine：Engine thrust-weight ratio less than 2 from developing to more than 10, the inlet temperature of gas turbine at present
1973K is alreadyd exceed, the temperature of military service parts is higher and higher, in order to protect the not oxidized corrosion failure of parts, last generation
It records the fifties, US National Aeronautics and Space Administration takes the lead in proposing thermal barrier coating concept, i.e.,：One layer of thermal boundary is deposited in matrix surface to apply
Layer, plays protection basis material.It is a kind of typical thermal insulation layer construction as shown in Figure 1, including：It arranges successively from bottom to top
Base layer 1 ', adhesive layer 2 ' and ceramic layer 3 '.
Thermal barrier coating due to severe working environment and applies series of strata during the application of engine thermal end pieces is on active service
It unites the material characteristics of itself, often causes the premature failure of thermal barrier coating, when thermal barrier coating is anti-in the air-flow with hard particles
Under multiple effect, theres is a phenomenon where thickness that thinning, crackle formed or even disbonding, destruction finish for the ceramic layer in the zone of action
The integrality of structure can directly have an impact the service life of equipment.In order to ensure the service safety of thermal barrier coating, a kind of energy is needed
Be enough in the detection method of practical military service operating mode, and can rapid monitoring coating convenient in real time by erosion state, and ensure
So that hot-end component is generated secondary destruction, ensures the safety of operating personnel.
The erosion test method of currently used coating non-destructive testing mainly has：Method of magnetic and eddy-current method, belong to contact
It measures, for the environment of thermal barrier coating service, contact, which is detected a flaw, is unfavorable for the operation of engineer, again cannot easily be achieved online inspection
It surveys.And the weight-loss method in traditional erosion test method, i.e., it is characterized by the weight loss after erosion, belongs to semidefinite scale
Sign, erosion depth and pattern for practical thermal barrier coating can not carry out quantitatively characterizing.Further, since weight-loss method is by liquidating
Erosion front and back coating quality loss characterizes degree of the coating by erosion, there is tested sample specification when laboratory carries out erosion experiment
Coating is deposited on high-temperature service portion when limiting, therefore laboratory can be analyzed and researched using such methods, and being actually on active service
The surface of part, military service severe and specification of changing commanders is big, therefore such method is not suitable for actually detected, is suitable only in the lab
Detection.
The patent document of Publication No. CN103063534A discloses a kind of simulate and is applied with real-time testing turbo blade thermal boundary
The experimental rig of layer erosion, thermal barrier coating to be measured need to adulterate pure cobalt powder in the preparation in order to detect, utilize the device
The erosion test method of progress is only applicable to that the erosion of thermal barrier coating is simulated and tested in laboratory, and past in practical engineering application
Toward the pure cobalt powder that undopes, therefore practical engineering application is not suitable for it.
The patent document of Publication No. CN103776382A and CN105588516A, individually disclose the film thickness of multi-layer ceramics
Assay method and a kind of film thickness measurement method based on terahertz pulse spectrum, they are tested more using Terahertz Technology
The thickness and film thickness of layer ceramics, can measure the thickness change at different location by the delay time of reflection peak, from
Depending on scale levies in kind border thermal barrier coating thickness, i.e. erosion depth.But it needs to obtain by other means in advance and is tested material
Light refractive index parameter, that is, need to re-start that prepared by sample and experiment could extract the refractive index of measured material, and again
The sample of preparation can not ensure identical with the refractive index of sample to be tested, and there are errors, and if Practical Project need when using
The refractive index of measured material can just be obtained by adding new experiment, then greatly reduces convenience；In addition this two parts of patent documents
Content in be not related to thermal barrier coating erosion measure application, thermal barrier coating after by erosion remaining coat inside can increase newly
Crackle and hole, this can cause the refractive index of ceramic layer to change, if according to original THICKNESS CALCULATION model and refraction
Rate carries out the THICKNESS CALCULATION after erosion, will introduce large error, if being continuing with this method measures the coating after erosion
Thickness, substantial measurement errors can constantly increase with the progress of erosion.
Invention content
The present invention is intended to provide the test method of the erosion pattern of the thermal barrier coating based on Terahertz Technology, to save individually
The step of measuring the refractive index of thermal barrier coating, and reduce error caused by the variations in refractive index of thermal barrier coating before and after erosion.
To achieve the goals above, the present invention provides a kind of erosion patterns of the thermal barrier coating based on Terahertz Technology
Test method has the thermal barrier coating of ceramic layer for measuring one, including：Step S1：Utilize reflective terahertz time-domain spectroscopy
Systematic vertical emits terahertz pulse to a complete thermal barrier coating, obtains the time-domain spectroscopy figure of complete thermal barrier coating；Step
Rapid S2：Value at the time of extracting the preceding triple reflection peak of complete thermal barrier coating in time-domain spectroscopy figure described in step S1 obtains
The time delays Δ t of the adjacent reflection peak twice of complete thermal barrier coating；Step S3：Calculate the ceramic layer of complete thermal barrier coating
Refractive index n；Step S4：Calculate the original depth D of the ceramic layer of thermal barrier coating；Step S5：The thermal barrier coating is removed, to institute
It states thermal barrier coating and carries out erosion；Step S6：The thermal barrier coating after erosion is scanned, is sent out using reflective terahertz time-domain spectroscopy system
It penetrates terahertz pulse and obtains multiple time-domain spectroscopy figures corresponding to continuous multiple measurement point measurements of the thermal barrier coating after the erosion；
Step S7：The first of the measurement point of the thermal barrier coating after erosion is extracted in time-domain spectroscopy figure described in each step S6 respectively
Value at the time of secondary reflection peak, and value is obtained as difference at the time of first reflection peak with the complete thermal barrier coating of step S2 extraction
Difference DELTA T, and according to the thinned thickness deltat D of the thermal barrier coating after the mathematic interpolation erosion；Step S8：According to the Δ being calculated
D values, are depicted as line chart, obtain the erosion pattern of thermal barrier coating.
The step S3 includes：Step S31：It is respectively obtained in the time-domain spectroscopy figure described in step S1 using Fourier transformation
Preceding triple reflection peak spectrogram；Step S32：It is read respectively on the spectrogram at the preceding triple reflection peak described in step S31
The spectral intensity F at preceding triple reflection peakS、FR1And FR2；Step S33：According to the spectral intensity F at preceding triple reflection peakS、FR1And FR2
Calculate the refractive index n of the ceramic layer of complete thermal barrier coating；The step S32 and step S33 is repeated several times in step S34, and right
Refractive index n takes mean value.
In the step S32, it is used as abscissa by choosing any Frequency point in the frequency range of 0.3-0.5THZ, preceding
The value that corresponding ordinate is read on the spectrogram at triple reflection peak is the spectral intensity F at preceding triple reflection peakS、FR1And FR2；And
All Frequency points that the step S34 repeats to choose in the frequency range of 0.3-0.5THZ come repeating said steps S32 and step S33.
The refractive index n of the ceramic layer of thermal barrier coating described in step S33 is
Wherein, FS、FR1And FR2The spectral intensity at respectively preceding triple reflection peak.
The original depth D of the ceramic layer of the complete thermal barrier coating is
Wherein, c is the aerial spread speed of light, and n is the refractive index of the ceramic layer of complete thermal barrier coating, and Δ t is
The time delays of the adjacent reflection peak twice of complete thermal barrier coating.
The thinned thickness deltat D of thermal barrier coating after the erosion is
C is the aerial spread speed of light, and Δ T is the first reflection peak of the measurement point of the thermal barrier coating after erosion
The difference of value at the time of moment value and the first reflection peak of complete thermal barrier coating.
The scanning of the step S6 is carried out along a current straight line.
The test method of the erosion pattern of the thermal barrier coating based on Terahertz Technology further includes step S9：It will be a plurality of flat
Row is set as current straight line successively in the update straight line of current straight line, and respectively repeats steps S6-S8, obtains being located at for thermal barrier coating
Erosion shape characteristic on a plurality of parallel scanned straight lines.
After step s 4 is completed, the mobile thermal barrier coating, and step S1-S4 is repeated, it repeatedly measures and obtains ceramic layer
Original depth D simultaneously takes mean value.
The reflective terahertz time-domain spectroscopy system or the thermal barrier coating are fixed on a gearshift.
The test method of the erosion pattern of the thermal barrier coating based on Terahertz Technology of this method only by it is reflective too
Hertz time-domain spectroscopy system emits the time-domain spectroscopy figure that a terahertz pulse is obtained to a complete thermal barrier coating to calculate thermal boundary
The refractive index of coating, and then the thickness of the ceramic layer of thermal barrier coating is calculated, time delays and folding can be obtained simultaneously when measuring
The step of penetrating rate, saving the refractive index of independent measurement thermal barrier coating；In addition, the present invention directly measures the thermal barrier coating before and after erosion
First reflection peak at the time of value variable quantity, therefore after calculating erosion can be carried out using the refractive index (n=1) of air
The thinned thickness of thermal barrier coating, need not be calculated using the refractive index of thermal barrier coating, before and after erosion
Error caused by the variations in refractive index of thermal barrier coating.
Description of the drawings
Fig. 1 is a kind of structural schematic diagram of typical thermal barrier coating.
Fig. 2 is the structural schematic diagram of reflective terahertz time-domain spectroscopy system of the present invention.
Fig. 3 is the test of the erosion pattern of the thermal barrier coating according to an embodiment of the invention based on Terahertz Technology
The time-domain spectroscopy figure and its principle schematic of method.
Fig. 4 is the spectrogram changed as Fourier to the preceding triple reflection peak of time-domain spectroscopy figure as shown in Figure 3.
Fig. 5 is the test of the erosion pattern of the thermal barrier coating according to an embodiment of the invention based on Terahertz Technology
Method to the thermal barrier coating after erosion along the time-domain spectroscopy figure of 6 measurement points of linear scanning.
Fig. 6 is by the erosion shape characteristic schematic diagram as determined by Fig. 5.
Specific implementation mode
Below in conjunction with the accompanying drawings, presently preferred embodiments of the present invention is provided, and is described in detail, makes to be better understood when this hair
Bright function, feature.
Terahertz typically refers to frequency in 0.1-10THz, wave-length coverage in 0.03-3mm, between radio wave and light wave it
Between electromagnetic radiation, be otherwise known as far infrared in optical field Terahertz.Because Terahertz has frequency high, pulse is short, differentiates
The features such as rate is high, and photon energy is low, and compared with traditional detection mode have the advantages that it is safe and efficient, without contacting and lossless, as
A kind of new technology, at present in field of non destructive testing extensive use.In view of the design feature of thermal barrier coating, top layer ceramic layer is dielectric
Material, intermetallic metal adhesive layer and protected basal layer belong to conductive material, because Terahertz can penetrate dielectric material
And conductive material can not be penetrated, so can occur on the interface of air and ceramic layer when Terahertz vertical incidence reflection and thoroughly
It penetrates, and emits on the interface of ceramic layer and metal bonding coating, the time delays between multiple reflections peak and ceramic layer
Thickness it is in a linear relationship, slope coefficient be ceramic material refractive index.
Based on this, the present invention provides a kind of test method of the erosion pattern of the thermal barrier coating based on Terahertz Technology,
For measuring a thermal barrier coating with ceramic layer, thermal barrier coating can be rushed using reflective terahertz time-domain spectroscopy system
Erosion is tested.The test side of the erosion pattern of thermal barrier coating according to an embodiment of the invention based on Terahertz Technology
Method includes the following steps：
Step S1：Emit terahertz pulse to a complete thermal boundary using reflective terahertz time-domain spectroscopy systematic vertical to apply
Layer, obtains the time-domain spectroscopy figure of complete thermal barrier coating.
As shown in Figure 1 and as described above, typical thermal barrier coating includes the base layer 1 ' arranged successively from bottom to top, glues
Tie layer 2 ' and ceramic layer 3 '.In the present embodiment, thermal barrier coating is prepared using air plasma spraying method.Base layer 1 '
Material be nickel-base alloy 738,2 ' material of adhesive layer be metal, preferably NiCrAlY, 3 ' material selection sintering crushing of ceramic layer
8Y2O3-ZrO2It is prepared by powder.After utilizing 1 ' to 200-300 DEG C of spray gun preheated substrate layer in the case of not powder feeding first, directly
It is connected on base layer 1 ' and sprays NiCrAlY powder, to which adhesive layer 2 ' be prepared.At this point, voltage is set as 60V, electric current setting
For 500A, main atmospheric pressure is 0.4MPa, Hydrogen Vapor Pressure 0.25MPa；Spray gun movement speed is set as 150mm/s, spray distance
For 100mm, powder feeding rate is 10g/min.The thickness control of adhesive layer 2 ' is at 150 μm or so.Then ceramic coated top layer is (i.e. ceramic
Layer 3 '), equally in the case of not powder feeding utilize spray gun by substrate preheating to 750 DEG C.At this point, voltage is 65V, electric current is
600A, main atmospheric pressure are 0.4MPa, Hydrogen Vapor Pressure 0.25MPa.Spray gun movement speed is set as 150mm/s, and spray distance is
80mm, powder feeding rate are 15g/min or so.Range or so of the 3 ' thickness control of ceramic layer at 400 μm.
The concrete structure of the reflective terahertz time-domain spectroscopy system 10 of the present invention is as shown in Fig. 2, which includes：
Laser 101, the first beam splitter 102, photoconductive exploring antenna 108, the mirror phase amplifier arranged successively along the trend of light path
109, computer 110；Wherein the centre wavelength of the laser 101 be 1560nm, repetition rate 100MHZ,；First beam splitter
It is equipped with the optical time delay portion 103 being arranged in the first light path between 102 and photoconductive exploring antenna 108 and is arranged in second successively
Photoconductive transmitting antenna 105, the second beam splitter 106 in light path；Photoconductive transmitting antenna 105 is equipped with a DC polarization device
104, for applying bias voltage to photoconductive transmitting antenna 105, to generate terahertz pulse.
Its operation principle is as follows：In use, by 107 face of a complete thermal barrier coating, one reflective terahertz time-domain spectroscopy
The side of second beam splitter 106 of system is placed, to complete thermal boundary before making terahertz pulse impinge perpendicularly on the non-erosion
The surface of coating 107.The laser 101 of reflective terahertz time-domain spectroscopy system exports a terahertz pulse, the Terahertz arteries and veins
Punching is divided into detection light and pump light after the first beam splitter 102.Pump light is incident on first on a photoconductive transmitting antenna 105,
Since DC polarization device 104 applies voltage to the photoconduction transmitting antenna 105, pump light just produces terahertz when reaching antenna
Hereby pulse, and the terahertz pulse of generation is then impinged perpendicularly on to the side for being set to the second beam splitter 106 through beam splitter 106
Thermal barrier coating 107 on, due to the second beam splitting of the reflective terahertz time-domain spectroscopy system of the surface face of the thermal barrier coating 107
Device 106 to be reflected back in the second beam splitter 106 from the terahertz pulse that the second beam splitter 106 emits, and enters through beam splitter
It is mapped on photoconductive exploring antenna 108.Detection light is incident on by optical time delay portion 103 on photoconductive exploring antenna 108, optics
The setting in delay portion 103 to detect light and terahertz pulse while reaching photoconductive exploring antenna 108, for signal point
Analysis.Amplify through lock-in amplifier 109 after reaching the detection light and terahertz pulse of photoconductive exploring antenna 108, to ensure locking phase
Function and the data of signal stablize acquisition, after be transmitted to computer 110, computer 110 for data final receiving and locate
Reason.
In the present embodiment, thermal barrier coating 107 is fixed on a gearshift 111, to realize thermal barrier coating 107 and anti-
The relative movement of formula terahertz time-domain spectroscopy system is penetrated, the accuracy of displacement and measurement angle when ensureing to measure.In addition, reflective
Terahertz time-domain spectroscopy system can also be fixed on instead of thermal barrier coating 107 on gearshift 111.
Step S2：Complete thermal barrier coating is extracted in the time-domain spectroscopy figure of complete thermal barrier coating described in step S1
Value at the time of preceding triple reflection peak obtains the time delays Δ t of adjacent reflection peak twice in the time-domain spectroscopy figure；
Fig. 3 is the terahertz time-domain spectroscopy figure and propagation path schematic diagram for the thermal barrier coating that step S1 is obtained.Wherein, terahertz
Hereby the first reflection peak in time-domain spectroscopy figure is S, and second of reflection peak is R1, and third time reflection peak is R2, first reflection
Peak S is represented by being back to the terahertz time-domain light through air and the reflection of ceramic layer interface after the transmitting of terahertz time-domain spectroscopy system
The terahertz pulse of spectra system, second of reflection peak R1 are represented by passing through enamel coating after the transmitting of terahertz time-domain spectroscopy system and through pottery
The interface of enamel coating and adhesive layer is back to the terahertz pulse of the terahertz time-domain spectroscopy system, and third time reflection peak R2 is represented
Enamel coating and interface, air and ceramic layer boundary through ceramic layer and adhesive layer are passed through after being emitted by terahertz time-domain spectroscopy system
The terahertz pulse of the terahertz time-domain spectroscopy system is back to after the interface triple reflection in face, ceramic layer and adhesive layer.
As shown in figure 3, the corresponding abscissa at the preceding triple reflection peak in time-domain spectroscopy figure is respectively its moment value, and
The difference of abscissa corresponding to adjacent reflection peak twice is time delays Δ t.
Step S3：The refractive index n for calculating the ceramic layer of complete thermal barrier coating, specifically includes：
Step S31：The preceding triple reflection peak in the time-domain spectroscopy figure described in step S1 is respectively obtained using Fourier transformation
Spectrogram；
It is illustrated in figure 4 the spectrogram at the preceding triple reflection peak in the time-domain spectroscopy figure obtained using Fourier transformation.
Step S32：Suitable abscissa (i.e. Frequency point) is chosen on spectrogram described in step S31 respectively and reads first three
The spectral intensity F at secondary reflection peakS、FR1And FR2；
The spectral intensity at corresponding preceding triple reflection peak is denoted as FS、FR1And FR2。
According to consulting literatures it is found that firstly because be suitble to calculate in the data volume abundances of 0.1-0.5THZ frequency ranges, and examine
Consider the scattering of low-frequency range, therefore, for the reasonability for ensureing value and the scattering for avoiding low-frequency range larger, needs to choose
F of the frequency range of the spectrogram abscissa of step S2 in the frequency range of 0.3~0.5THZS、FR1And FR2Data carry out | γ |
It calculates, particular by the frequency range of 0.3-0.5THZ, choosing some Frequency point as abscissa, at preceding triple reflection peak
Spectrogram on read corresponding ordinate value be preceding triple reflection peak spectral intensity FS、FR1And FR2, such as：Abscissa takes
The ordinate value of 0.3THZ, the correspondence 0.3THZ at preceding triple reflection peak are FS、FR1And FR2To avoid the error of data excessive.
Step S33：According to the spectral intensity F at preceding triple reflection peakS、FR1And FR2Calculate the ceramic layer of complete thermal barrier coating
Refractive index n.
Wherein, the refractive index n of the ceramic layer of complete thermal barrier coating is calculated according to following formula：
Wherein, the spectral intensity at triple reflection peak before FS, FR1 and FR2 are respectively.
Step S34：Above steps may be repeated multiple times S32 and step S33, and refractive index n takes mean value.Wherein, the step weight
All Frequency points in the frequency range of 0.3-0.5THZ are had chosen again come the S32 and step S33 that repeats the above steps, and thus obtained
The mean value of refractive index n so that the error smaller of refractive index n.
Step S4：Calculate the original depth D of the ceramic layer of thermal barrier coating.
The original depth D of the ceramic layer of thermal barrier coating is calculated with specific reference to following measurement model：
Wherein, c is the aerial spread speed of light, and n is the refractive index of the ceramic layer of complete thermal barrier coating, and Δ t is
The time delays of the adjacent reflection peak twice of complete thermal barrier coating.
Preferably, the test method of the erosion pattern of the thermal barrier coating of the invention based on Terahertz Technology further includes：
After the completion of step S4, the mobile thermal barrier coating, and step S1-S4 is repeated, the original depth D that multiple measurement obtains ceramic layer takes
Mean value.Thus, it is possible to reduce the error of the original depth D of ceramic layer.
Step S5：The thermal barrier coating is removed, erosion is carried out to the thermal barrier coating.
In order to obtain the sample after erosion, the present invention impacts thermal barrier coating after using the moist steam with erosion abrasive material to accelerate
Surface, with to the thermal barrier coating carry out erosion.Wherein erosion abrasive material is diamond dust, and grain size is 61-75 μm, and powder feeding rate is about
5.12g/min, moist steam are that originally water vapour, steam flow 6.5-7kg/h are vertically beaten in coating table according to 90 degree of erosion angles
Face, erosion time control is in 180-210s.
Step S6：Thermal barrier coating after a current linear scanning erosion, utilizes reflective terahertz time-domain spectroscopy system
Transmitting terahertz pulse simultaneously obtains multiple time-domain spectroscopies corresponding to continuous multiple measurement point measurements of the thermal barrier coating after the erosion
Figure.Wherein, thermal barrier coating moves along a straight line, and the spacing of adjacent measurement points is 1.5mm.In the present embodiment, the measurement point
Quantity be 6, the time-domain spectroscopy figure corresponding to continuous 6 measurement points of thermal barrier coating is as shown in Figure 5.In addition, measurement point
Quantity can increase or decrease.
Step S7：The measurement point of the thermal barrier coating after erosion is extracted in time-domain spectroscopy figure described in each step S6
Value at the time of first reflection peak, and at the time of first reflection peak with the complete thermal barrier coating of step S2 extraction value make it is poor
Difference DELTA T is obtained, and according to the thinned thickness deltat D of the thermal barrier coating after the mathematic interpolation erosion.
Wherein, the thickness deltat D thinned because of erosion of the thermal barrier coating after erosion is calculated with specific reference to following measurement model：
C is the aerial spread speed of light, and Δ T is the first reflection peak of the measurement point of the thermal barrier coating after erosion
The difference of value at the time of moment value and the first reflection peak of complete thermal barrier coating.
In the present embodiment, the data of the difference DELTA T of different erosion degree position (point 1-6) and the Δ D being calculated are shown in
The following table 1.
Step S8：According to the Δ D values being calculated, it is depicted as line chart as shown in FIG. 6, obtains being located at for thermal barrier coating
Erosion pattern at one linear position；
In addition, the scanning in above-mentioned steps S6 can think that the path of setting is measured along arbitrary gauger, and not only
It is limited to along a current linear scanning, finally can not only obtains the shape characteristic on line, this measuring surface can be characterized in fact
Shape characteristic, in the present embodiment, it is contemplated that measuring condition, test method of the invention can also include step S9：It will be a plurality of
The update straight line for being parallel to current straight line is set as current straight line successively, and respectively repeats steps S6-S8, obtains the position of thermal barrier coating
Erosion shape characteristic on a plurality of parallel scanned straight lines, quantity and terahertz time-domain spectroscopy system of the measuring accuracy by scanning element
The resolving accuracy of system codetermines.The step sweeps (parallel or vertical) by carrying out a plurality of line, can characterize so tested
The shape characteristic in face.Step S9 can also be omitted according to specific needs.
Above-described, only presently preferred embodiments of the present invention is not limited to the scope of the present invention, of the invention is upper
Stating embodiment can also make a variety of changes.Made by i.e. every claims applied according to the present invention and description
Simply, equivalent changes and modifications fall within the claims of patent of the present invention.The not detailed description of the present invention is
Routine techniques content.
Claims (10)
1. a kind of test method of the erosion pattern of the thermal barrier coating based on Terahertz Technology has ceramic layer for measuring one
Thermal barrier coating, which is characterized in that including：
Step S1：Emit terahertz pulse to a complete thermal barrier coating using reflective terahertz time-domain spectroscopy systematic vertical,
Obtain the time-domain spectroscopy figure of complete thermal barrier coating；
Step S2：At the time of extracting the preceding triple reflection peak of complete thermal barrier coating in time-domain spectroscopy figure described in step S1
Value, obtains the time delays Δ t of the adjacent reflection peak twice of complete thermal barrier coating；
Step S3：Calculate the refractive index n of the ceramic layer of complete thermal barrier coating；
Step S4：Calculate the original depth D of the ceramic layer of thermal barrier coating；
Step S5：The thermal barrier coating is removed, erosion is carried out to the thermal barrier coating；
Step S6：The thermal barrier coating after erosion is scanned, simultaneously using reflective terahertz time-domain spectroscopy system transmitting terahertz pulse
Continuous multiple measurement point measurements corresponding to the thermal barrier coating after the erosion obtain multiple time-domain spectroscopy figures；
Step S7：The measurement point of the thermal barrier coating after erosion is extracted in time-domain spectroscopy figure described in each step S6 respectively
Value at the time of first reflection peak, and at the time of first reflection peak with the complete thermal barrier coating of step S2 extraction value make it is poor
Difference DELTA T is obtained, and according to the thinned thickness deltat D of the thermal barrier coating after the mathematic interpolation erosion；
Step S8：According to the Δ D values being calculated, it is depicted as line chart, obtains the erosion pattern of thermal barrier coating.
2. the test method of the erosion pattern of the thermal barrier coating according to claim 1 based on Terahertz Technology, feature
It is, the step S3 includes：
Step S31：The frequency at the preceding triple reflection peak in the time-domain spectroscopy figure described in step S1 is respectively obtained using Fourier transformation
Spectrogram；
Step S32：The spectrum at triple reflection peak is strong before being read respectively on the spectrogram at the preceding triple reflection peak described in step S31
Spend FS、FR1And FR2；
Step S33：According to the spectral intensity F at preceding triple reflection peakS、FR1And FR2Calculate the folding of the ceramic layer of complete thermal barrier coating
Penetrate rate n；
The step S32 and step S33 is repeated several times in step S34, and refractive index n takes mean value.
3. the test method of the erosion pattern of the thermal barrier coating according to claim 2 based on Terahertz Technology, feature
It is, in the step S32, is used as abscissa by choosing any Frequency point in the frequency range of 0.3-0.5THZ, at first three
The value that corresponding ordinate is read on the spectrogram at secondary reflection peak is the spectral intensity F at preceding triple reflection peakS、FR1And FR2；And institute
It states all Frequency points that step S34 repeats to choose in the frequency range of 0.3-0.5THZ and comes repeating said steps S32 and step S33.
4. the test method of the erosion pattern of the thermal barrier coating according to claim 2 based on Terahertz Technology, feature
It is, the refractive index n of the ceramic layer of the complete thermal barrier coating described in step S33 is
Wherein, FS、FR1And FR2The spectral intensity at respectively preceding triple reflection peak.
5. the test method of the erosion pattern of the thermal barrier coating according to claim 4 based on Terahertz Technology, feature
It is, the original depth D of the ceramic layer of thermal barrier coating is
Wherein, c is the aerial spread speed of light, and n is the refractive index of the ceramic layer of complete thermal barrier coating, and Δ t is complete
Thermal barrier coating adjacent reflection peak twice time delays.
6. the test method of the erosion pattern of the thermal barrier coating according to claim 1 based on Terahertz Technology, feature
It is, the thinned thickness deltat D of the thermal barrier coating after the erosion is
C is the aerial spread speed of light, at the time of Δ T is the first reflection peak of the measurement point of the thermal barrier coating after erosion
The difference of value at the time of value and the first reflection peak of complete thermal barrier coating.
7. the test method of the erosion pattern of the thermal barrier coating according to claim 1 based on Terahertz Technology, feature
It is, the scanning of the step S6 is carried out along a current straight line.
8. the test method of the erosion pattern of the thermal barrier coating according to claim 7 based on Terahertz Technology, feature
It is, further includes step S9：The a plurality of update straight line for being parallel to current straight line is set as current straight line successively, and repeats to walk respectively
Rapid S6-S8 obtains the erosion shape characteristic of thermal barrier coating being located on a plurality of parallel scanned straight lines.
9. the test method of the erosion pattern of the thermal barrier coating according to claim 1 based on Terahertz Technology, feature
It is, after step s 4 is completed, the mobile thermal barrier coating, and step S1-S4 is repeated, it repeatedly measures and obtains the initial of ceramic layer
Thickness D simultaneously takes mean value.
10. the test method of the erosion pattern of the thermal barrier coating according to claim 1 based on Terahertz Technology, feature
It is, the reflective terahertz time-domain spectroscopy system or the thermal barrier coating are fixed on a gearshift.
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