CN117030775A - Broadband dual-laser excitation-based solid engine spray pipe adhesive curing viscosity photo-thermal characterization device and characterization method thereof - Google Patents

Abstract

A broadband dual-laser excitation-based solid engine spray pipe adhesive curing viscosity photo-thermal characterization device and a characterization method thereof. The computer (1) is sequentially connected with the first function generator (4) and the high-power semiconductor laser power supply (6), the high-power semiconductor laser power supply (6) is respectively connected with the high-power semiconductor laser (9) and the TEC refrigerator power supply (11), the TEC refrigerator power supply (11) is provided with the TEC semiconductor refrigerator (10), and the high-power semiconductor laser (9) is sequentially connected with the first collimating mirror (20), the first engineering diffuser (21) and the second polaroid (22); the computer (1) is also connected with a phase-locked detection amplifier (39), and the phase-locked detection amplifier (39) is sequentially connected with a preamplifier (15), an HCT heat detector (17), a first polaroid (18) and a band-pass filter (19). The invention solves the problem that the curing time of the solid engine spray pipe adhesive can not be quantified in the practical application process.

Description

Solid engine nozzle adhesive curing viscosity light based on broadband dual laser excitation Thermal characterization device and characterization method

Technical field

The invention belongs to the technical fields of photothermal science and detection and signal processing, and specifically relates to a photothermal characterization device and characterization method of solid engine nozzle adhesive solidified viscosity based on broadband dual laser excitation.

Background technique

The bonding of solid engine nozzles includes the bonding of the resin-based carbon fiber composite lining and the metal shell. The bonding effect is mainly determined by the surface state of the adherend, the performance of the adhesive and the characteristics of the interface layer. Since epoxy resin is active on many materials, the curing reaction is a nucleophilic addition reaction. It does not require high pressure during curing, and the bonding and molding process is simple. The formula selection based on this is also relatively easy. According to the curing temperature used, the corresponding curing agent is selected, taking into account the pot life and the performance of the adhesive after curing. In the actual application process, the E-51 epoxy resin and 2-ethyl-4-methylimidazole formula system adhesive is a medium-temperature curing epoxy resin structural adhesive. After long-term use of batch production models, it has been shown that it can meet the requirements of tactical missile solid Bonding between the metal casing and fiberglass lining of the long tail nozzle in rocket engines. The adhesive performance indicators, molding process, quality stability and reliability fully meet the product usage requirements. Based on the apparent kinetic equation, the complete curing time of the E-51 epoxy resin and 2-ethyl-4-methylimidazole formula system adhesive at the specified temperature can be roughly calculated. When the ambient temperature is set to 80°C, the complete curing time is 4.44 hours. Taking into account the effects of heat conduction and radiation between the material and the environment, the complete curing time is generally 6 to 8 hours in an 80°C environment. In order to ensure the effective bonding between the solid engine composite lining and the metal casing, bonding generally needs to be carried out at a certain point before the material is completely solidified. However, there is currently no empirical formula or theoretical formula for calculation reference at this time. After thorough research, the current production workshop still mainly relies on the actual engineering experience of bonding workers to determine this moment. The adhesive is used to touch the adhesive during the curing process with fingers. The best bonding occurs when the adhesive exhibits the effect of "drawing without sticking". pick up time.

In the existing technology, a terahertz time domain spectrometer is used to collect the terahertz time domain signal of the organic adhesive bonded sample after curing at room temperature for T1 time to obtain a terahertz data set. Make mathematical statistics on the variance value and flight time of each point in the variance imaging map and time-of-flight imaging map to form a histogram; perform Gaussian curve fitting on the histogram, and make statistics on the characteristic value μ of the Gaussian curve after fitting; repeat The above steps are carried out until the Gaussian curve characteristic value after normal temperature curing is completed; statistical analysis is performed on the Gaussian curve characteristic value of the organic adhesive bonded sample at each period of normal temperature curing to obtain a curve graph. This invention uses terahertz time-domain spectroscopy to obtain characteristic changes during the curing process, which can evaluate the curing of the adhesive to a certain extent. However, it lacks quantitative indicators and therefore cannot be quantitatively determined. Another prior art does not mention a method for detecting or quantifying the degree of curing. The existing technology also discloses using magnesium-aluminum alloy as the bonded material, using a nonlinear ultrasonic testing system to excite and receive longitudinal wave ultrasonic signals, and performing Fourier transform on the received ultrasonic signals to obtain the basis of ultrasonic signals transmitted through the bonded structure. The frequency amplitude and frequency multiplication amplitude are obtained, and the corresponding nonlinear coefficients are obtained, and finally the relationship between the nonlinear coefficients and the adhesive curing time is established. In this paper, a custom nonlinear coefficient is used to evaluate the degree of material solidification. The results are not interpretable. At the same time, the method is a contact measurement and is not suitable for scenarios requiring non-contact detection. When the existing technology takes 6061 aluminum alloy/modified acrylate glue/6061 aluminum alloy bonded specimens as the research object, collinear transverse wave and longitudinal wave mixing detection technology is used to experimentally study the resonance wave amplitude with the curing time of the bonding interface. Changes. The results show that there is an intrinsic relationship between the resonance wave amplitude, the number of randomly distributed cracks in the adhesive layer, and the curing time of the bonded specimen. However, this method is still a real-time monitoring method and lacks effective quantitative indicators for measuring the degree of material solidification.

Contents of the invention

The present invention provides a photothermal characterization device and characterization method for the solidified viscosity of a solid engine nozzle adhesive based on broadband dual laser excitation to solve the problem of being unable to quantify the solidifying time of the solid engine nozzle adhesive during practical application. The detection method and system are suitable for the field of accurate quantitative evaluation of solid engine nozzle adhesive curing viscosity and optimal curing time.

The present invention is realized through the following technical solutions:

A photothermal characterization device for solid engine nozzle adhesive solidified viscosity based on broadband dual laser excitation. The characterization device includes a computer 1, a first function generator 4, a high-power semiconductor laser power supply 6, and a high-power semiconductor laser 9 , TEC semiconductor refrigerator 10, TEC refrigerator power supply 11, first mounting bracket 13, large off-axis parabolic mirror 14, preamplifier 15, HCT thermal detector 17, first polarizer 18, bandpass filter 19, The first collimating lens 20, the first engineering diffuser 21, the second polarizing plate 22, the second collimating lens 23, the second engineering diffusing body 24, the third polarizing plate 25, the focusing plate 26, the small off-axis parabola Mirror 27, test piece 28, thermostat 29, two-dimensional micro-displacement moving stage 30, second mounting support 32, two-axis driver 33, low-power semiconductor laser 35, second function generator 37, phase-locked detection amplifier 39 , drive control line 41;

The computer 1 is connected to the first function generator 4 and the high-power semiconductor laser power supply 6 in turn. The high-power semiconductor laser power supply 6 is connected to the high-power semiconductor laser 9 and the TEC refrigerator power supply 11 respectively. The TEC refrigerator power supply A TEC semiconductor refrigerator 10 is provided on 11, and the high-power semiconductor laser 9 is connected to the first collimating mirror 20, the first engineering diffuser 21 and the second polarizing plate 22 in sequence;

The computer 1 is also connected to a lock-in detection amplifier 39, which is connected in turn to a preamplifier 15, an HCT thermal detector 17, a first polarizing plate 18 and a band-pass filter 19; the band-pass The filter 19 is used with a large off-axis parabolic mirror 14, which is arranged on the first mounting support 13;

The lock-in detection amplifier 39 is also connected to a second function generator 37, which is connected in sequence to the low-power semiconductor laser 35, the second collimating mirror 23, the second engineering diffuser 24, and the second function generator 37. The three polarizing plates 25 and focusing plate 26, the second engineering diffuser 24, the third polarizing plate 25 and the focusing plate 26 are embedded in the designated installation position of the small off-axis parabolic lens 27, the small off-axis parabolic lens 27 Set on the second mounting support 32;

The computer 1 is also connected to a two-axis driver 33. The two-axis driver 33 is connected to a two-dimensional micro-displacement mobile platform 30. A thermostatic box 29 is provided on the two-dimensional micro-displacement mobile platform 30. The thermostatic box 29 The test piece 28 is placed inside.

Further, the computer 1 is provided with two output signal terminals and one input/output signal terminal. The computer 1 is connected to the phase-locked detector amplifier 39 through the input/output signal terminal Ethernet cable 40. The computer 1 passes through the first output The first B-type USB data line 3 at the signal end is connected to the input signal end of the first function generator 4; the computer 1 drives the control line 41 through the second output signal end and is connected to the two-axis driver 33; the output of the phase-locked detection amplifier 39 The signal end is connected to the second function generator 37 through the second BNC data line 38; the input signal end of the phase-locked detection amplifier 39 is connected to the preamplifier 15 through the high-performance radio frequency coaxial cable 2; the second function generator 37 is connected through The second B-type USB data line 36 is connected to the low-power semiconductor laser 35, and the laser emitted by the low-power semiconductor laser 35 is transmitted to the second collimating mirror 23 through the second laser fiber 34;

The second engineered diffuser 24, the third polarizing plate 25 and the focusing plate 26 are embedded in the designated installation position of the small off-axis parabolic mirror 27; the test piece 28 is placed in the thermostatic box 29, and the thermostatic box 29 is placed in the two-dimensional microstructure. On the displacement moving stage 30, the position scanning detection of the test piece 28 has been realized; the small off-axis parabolic mirror 27 is installed on the second mounting support 32, and the large off-axis parabolic mirror 14 is installed on the first mounting support 13 ; The HCT thermal detector 17 is connected to the input signal end of the preamplifier 15 through a coaxial cable 16 to achieve amplification of the photothermal signal; the bandpass filter 19 and the first polarizer 18 are fixed on the HCT thermal detector through threaded connections. In front of the device 17, the bandpass filter 19 effectively filters out the near-infrared excitation light; the output signal end of the first function generator 4 is connected to the high-power semiconductor laser power supply 6 through the first BNC data line 5; the high-power semiconductor laser The power supply 6 is connected to the high-power semiconductor laser 9 and the TEC refrigerator power supply 11 through the semiconductor laser power supply line 7 and the TEC refrigerator power supply line 8 respectively, and the TEC semiconductor refrigerator 10 is located between the high-power semiconductor laser 9 and the TEC refrigerator power supply 11; The high-power semiconductor laser 9 transmits laser light to the first collimating mirror 20 through the first laser fiber 12. A first engineering diffuser 21 and a second polarizing plate 22 are respectively installed in front of the first collimating mirror 20.

A photothermal characterization method of solid engine nozzle adhesive solidified viscosity based on broadband dual laser excitation. The characterization method includes the following steps:

Step 1: Identify the piece to be tested 28, place the piece to be tested in the thermostat 29, open the thermostat 29, and set the temperature to 80°C;

Step 2: Turn on the photothermal characterization device for solid engine nozzle adhesive cured viscosity based on broadband dual laser excitation;

Step 3: Adjust the position of the two-dimensional micro-displacement moving stage 30 so that the test piece 28 is at the focus position of the small off-axis parabolic mirror 27. At the same time, adjust the first mounting support 13 so that the component detected by the HCT thermal detector 17 is at The focal position of the large off-axis parabolic mirror 14;

Step 4: The computer 1 issues an instruction to make the low-power semiconductor laser 35 generate a laser with a modulation frequency of 0 Hz through the phase-locked detection amplifier 39 and the second function generator 37. At this time, check whether the laser spot size is normal;

At the same time, the computer 1 issues an instruction to cause the high-power semiconductor laser power supply 6 to generate a laser with a modulation frequency of 0 Hz through the first function generator 4. At this time, check whether the laser emitted by the first collimating mirror 20 completely covers the test piece 28;

Step 5: Observe whether the signal obtained by the lock-in detection amplifier 39 from the HCT thermal detector 17 is within the measurement range. If it is not within the measurement range, you need to adjust the preamplifier 15 to amplify or reduce the gain;

Step 6: When the temperature of the test piece 28 reaches the set temperature, start timing, and carry out a broadband dual-laser excitation adhesive curing viscosity photothermal characterization test at 0 hours 0h, in which the modulation of the low-power semiconductor laser 35 is set The frequency band range is, and the frequency of the high-power semiconductor laser power supply 6 is 0Hz and the power is 45W;

Step 7: Then conduct a broadband dual-laser excitation photothermal characterization test of the cured viscosity of the adhesive every 1 hour, and then determine whether it is the best bonding time based on the hand touch of the worker, and record the photothermal response characteristic data. Record 0-5 hours;

Step 8: After the 5-hour test data is completed, a dual-laser excitation-induced thermal radiation signal response model needs to be established based on the characteristics of the test piece to achieve a quantitative assessment of the degree of curing;

Step 9: At the end of the test, save the broadband scanning results and fitting results obtained from the test. At the same time, the computer 1 controls the high-power semiconductor laser power supply 6 and the low-power semiconductor laser 35 so that the light intensity becomes 0, and controls the two-axis driver at the same time. 33. Return the two-dimensional micro-displacement moving stage 30 to zero and turn off the heating function of the thermostatic box 29;

Step 10: After the test, after an interval of 5 minutes, turn off the first function generator 4, the high-power semiconductor laser power supply 6, the two-axis driver 33, the preamplifier 15, the HCT thermal detector 17, and the second function generator 37. , phase-locked detection amplifier 39. After the thermostat 29 returns to room temperature, place the test piece 28 into a designated storage container.

Further, the dual laser excitation-induced thermal radiation signal response model for the characteristics of the test piece in step 8 is specifically as follows:

In the formula, K ₁ is the response gain of the HCT thermal detector, k is the thermal conductivity of the test piece, h is the convection heat transfer coefficient existing on the surface of the test piece, α _IR (λ) is the infrared absorption coefficient of the test piece; L ₁ is Thickness of the piece to be tested; σ is the Stefan-Boltzmann constant; β is the light absorption attenuation coefficient of the piece to be tested.

Further, the relationship between the thermal radiation signal of the test piece and the surface temperature signal is as follows:

In the formula, K is the system scale factor; P(λ) is the spectral response frequency band of the HCT thermal detector; ε is the emissivity of the test piece; T ₀ is the room temperature; λ ₁ and λ ₂ are the spectral response ranges of the HCT thermal detector respectively. .

Furthermore, since the signal S(ω) is a complex quantity, the amplitude-frequency and phase-frequency dynamic responses of the photothermal radiation of the test piece under modulation laser action can be directly obtained, that is:

Multi-parameter fitting is to find the best parameters, so that the amplitude and phase information calculated by the mathematical model at the best parameters and the amplitude and phase information obtained through experiments are brought into the objective function G, so that G reaches the minimum value.

Further, the objective function of the multi-parameter fitting is,

In the formula, Z ₁ and Z ₂ are scaling factors; g is the coefficient to be fitted; n is the number of collection points; _fi is the modulation frequency; Ampl ^T and Phase ^T are the calculated amplitude and phase; Ampl ^E and Phase ^E are the tests. Obtained amplitude and phase characteristic data.

The beneficial effects of the present invention are:

The invention can effectively identify the optimal curing time of the solid engine nozzle adhesive, the thickness of the adhesive covers 20 μm to 200 μm, the characteristic phase difference between the optimal cured and uncured adhesive is greater than 30 degrees, and the dual laser excitation photothermal radiation response The signal frequency covers 0.01Hz~102KHz. At the same time, the adhesive curing time can be quantitatively evaluated based on the thermal conductivity and thermal diffusion coefficient inversion resin. The inversion accuracy of thermal conductivity and thermal diffusion coefficient is better than 10 ^-4 W/m℃ and 10 ^-3 m ² respectively. /s.

The invention can also be applied to various technical fields such as photothermal performance evaluation of high molecular polymers and real-time monitoring and quantitative evaluation of the curing degree of aerospace adhesives.

Compared with detection methods such as ultrasound and terahertz time domain spectroscopy, this invention can make full use of the advantages of non-contact photothermal radiation, tunable laser, and high heat injection efficiency. At the same time, it uses dual-channel detection operations to filter high-frequency harmonics such as noise. The advantage of the wave signal is that it can effectively extract characteristic information including the degree of adhesive curing, and can effectively identify the optimal curing time of the solid engine nozzle adhesive, detect the thickness of the adhesive covering 20 μm to 200 μm, and determine the optimal cured and uncured adhesive. The characteristic phase difference of the joints is greater than 30 degrees.

Description of the drawings

Figure 1 is a schematic structural diagram of the present invention.

Figure 2 is a schematic diagram of the test piece of the present invention.

Figure 3 shows the broadband thermal radiation response results of the solid engine nozzle adhesive sample of the present invention at different curing times, including (a) amplitude-frequency response results and (b) phase-frequency response results.

Figure 4 is the characteristic results of the solid engine nozzle adhesive sample of the present invention at specific frequencies at different curing times, including (a) amplitude and (b) phase.

Figure 5 is the fitting result of the present invention.

Figure 6 is the inversion result of the thermal conductivity and thermal diffusion coefficient of the solid engine nozzle adhesive of the present invention, where (a) the thermal conductivity fitting result, (b) the thermal diffusion coefficient fitting result.

1-Computer, 2-High performance RF coaxial cable, 3-First type B USB data cable, 4-First function generator, 5-First BNC data cable, 6-High power semiconductor laser power supply, 7- Semiconductor laser power supply line, 8-TEC refrigerator power supply line, 9-high power semiconductor laser, 10-TEC semiconductor refrigerator, 11-TEC refrigerator power supply, 12-first laser fiber, 13-first installation support, 14 -Large off-axis parabolic mirror, 15-preamplifier, 16-coaxial cable, 17-HCT thermal detector, 18-first polarizer, 19-bandpass filter, 20-first collimating mirror, 21 -The first engineering diffuser, 22-the second polarizing plate, 23-the second collimating lens, 24-the second engineering diffuser, 25-the third polarizing plate, 26-focusing plate, 27-small off-axis parabola Mirror, 28-piece to be tested, 29-thermostat box, 30-two-dimensional micro-displacement moving stage, 31-motion control line, 32-second installation support, 33-two-axis driver, 34-second laser fiber, 35 -Low power semiconductor laser, 36-second type B USB data line, 37-second function generator, 38-second BNC data line, 39-phase lock-in detection amplifier, 40-Ethernet line, 41-drive control line

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

A photothermal characterization device for solid engine nozzle adhesive solidified viscosity based on broadband dual laser excitation. The characterization device includes a computer 1, a first function generator 4, a high-power semiconductor laser power supply 6, and a high-power semiconductor laser 9 , TEC semiconductor refrigerator 10, TEC refrigerator power supply 11, first mounting bracket 13, large off-axis parabolic mirror 14, preamplifier 15, HCT thermal detector 17, first polarizer 18, bandpass filter 19, The first collimating lens 20, the first engineering diffuser 21, the second polarizing plate 22, the second collimating lens 23, the second engineering diffusing body 24, the third polarizing plate 25, the focusing plate 26, the small off-axis parabola Mirror 27, test piece 28, thermostat 29, two-dimensional micro-displacement moving stage 30, second mounting support 32, two-axis driver 33, low-power semiconductor laser 35, second function generator 37, phase-locked detection amplifier 39 , drive control line 41;

The computer 1 is connected to the first function generator 4 and the high-power semiconductor laser power supply 6 in turn. The high-power semiconductor laser power supply 6 is connected to the high-power semiconductor laser 9 and the TEC refrigerator power supply 11 respectively. The TEC refrigerator power supply A TEC semiconductor refrigerator 10 is provided on 11, and the high-power semiconductor laser 9 is connected to the first collimating mirror 20, the first engineering diffuser 21 and the second polarizing plate 22 in sequence;

The computer 1 is also connected to a lock-in detection amplifier 39, which is connected in turn to a preamplifier 15, an HCT thermal detector 17, a first polarizing plate 18 and a band-pass filter 19; the band-pass The filter 19 is used with a large off-axis parabolic mirror 14, which is arranged on the first mounting support 13;

The lock-in detection amplifier 39 is also connected to a second function generator 37, which is connected in sequence to the low-power semiconductor laser 35, the second collimating mirror 23, the second engineering diffuser 24, and the second function generator 37. The three polarizing plates 25 and focusing plate 26, the second engineering diffuser 24, the third polarizing plate 25 and the focusing plate 26 are embedded in the designated installation position of the small off-axis parabolic lens 27, the small off-axis parabolic lens 27 Set on the second mounting support 32;

The computer 1 is also connected to a two-axis driver 33. The two-axis driver 33 is connected to a two-dimensional micro-displacement mobile platform 30. A thermostatic box 29 is provided on the two-dimensional micro-displacement mobile platform 30. The thermostatic box 29 The test piece 28 is placed inside.

Further, the computer 1 is provided with two output signal terminals and one input/output signal terminal. The computer 1 is connected to the phase-locked detector amplifier 39 through the input/output signal terminal Ethernet cable 40. The computer 1 passes through the first output The first B-type USB data line 3 at the signal end is connected to the input signal end of the first function generator 4; the computer 1 drives the control line 41 through the second output signal end and is connected to the two-axis driver 33; the output of the phase-locked detection amplifier 39 The signal end is connected to the second function generator 37 through the second BNC data line 38; the input signal end of the phase-locked detection amplifier 39 is connected to the preamplifier 15 through the high-performance radio frequency coaxial cable 2; the second function generator 37 is connected through The second B-type USB data line 36 is connected to the low-power semiconductor laser 35, and the laser emitted by the low-power semiconductor laser 35 is transmitted to the second collimating mirror 23 through the second laser fiber 34;

The second engineered diffuser 24, the third polarizing plate 25 and the focusing plate 26 are embedded in the designated installation position of the small off-axis parabolic mirror 27; the test piece 28 is placed in the thermostatic box 29, and the thermostatic box 29 is placed in the two-dimensional microstructure. On the displacement moving stage 30, the position scanning detection of the test piece 28 has been realized; the small off-axis parabolic mirror 27 is installed on the second mounting support 32, and the large off-axis parabolic mirror 14 is installed on the first mounting support 13 ; The HCT thermal detector 17 is connected to the input signal end of the preamplifier 15 through a coaxial cable 16 to achieve amplification of the photothermal signal; the bandpass filter 19 and the first polarizer 18 are fixed on the HCT thermal detector through threaded connections. In front of the device 17, the bandpass filter 19 effectively filters out the near-infrared excitation light; the output signal end of the first function generator 4 is connected to the high-power semiconductor laser power supply 6 through the first BNC data line 5; the high-power semiconductor laser The power supply 6 is connected to the high-power semiconductor laser 9 and the TEC refrigerator power supply 11 through the semiconductor laser power supply line 7 and the TEC refrigerator power supply line 8 respectively, and the TEC semiconductor refrigerator 10 is located between the high-power semiconductor laser 9 and the TEC refrigerator power supply 11; The high-power semiconductor laser 9 transmits laser light to the first collimating mirror 20 through the first laser fiber 12. A first engineering diffuser 21 and a second polarizing plate 22 are respectively installed in front of the first collimating mirror 20.

The photothermal characterization device for solid engine nozzle adhesive solidified viscosity based on broadband dual laser excitation is implemented as shown in Figure 1. The modulated light used in the test in this embodiment is an 808nm low-power semiconductor laser 35 (laser power 32mW). , spot diameter 600μm), DC light is a high-power semiconductor laser 9 with a wavelength of 808nm (laser power 45W, coverage area 100mm×100mm); HCT thermal detector 17 (detection band 2μm~12μm, detection area 100μm×100μm); relevant detection is applicable The frequency band is 0.01Hz~102KHz, and the test scanning frequency range is 100Hz~100KHz. The test piece 28 is an adhesive formulated with E-51 epoxy resin and 2-ethyl-4-methylimidazole, with a thickness of 150 μm.

A photothermal characterization method of solid engine nozzle adhesive solidified viscosity based on broadband dual laser excitation. The characterization method includes the following steps:

Step 1: Identify the piece to be tested 28, place the piece to be tested in the thermostat 29, open the thermostat 29, and set the temperature to 80°C;

Step 2: Turn on the photothermal characterization device for solid engine nozzle adhesive cured viscosity based on broadband dual laser excitation; this process includes the first function generator 4, high-power semiconductor laser power supply 6, preamplifier 15, HCT thermal Turning on the detector 17, phase-locked detection amplifier 39, second function generator 37, two-axis driver 33 and other equipment;

Step 3: Adjust the position of the two-dimensional micro-displacement moving stage 30 so that the test piece 28 is at the focus position of the small off-axis parabolic mirror 27. At the same time, adjust the first mounting support 13 so that the component detected by the HCT thermal detector 17 is at The focal position of the large off-axis parabolic mirror 14;

Step 4: The computer 1 issues an instruction to make the low-power semiconductor laser 35 generate a laser with a modulation frequency of 0 Hz through the phase-locked detection amplifier 39 and the second function generator 37. At this time, check whether the laser spot size is normal;

At the same time, the computer 1 issues an instruction to cause the high-power semiconductor laser power supply 6 to generate a laser with a modulation frequency of 0 Hz through the first function generator 4. At this time, check whether the laser emitted by the first collimating mirror 20 completely covers the test piece 28;

Step 5: Observe whether the signal obtained by the lock-in detection amplifier 39 from the HCT thermal detector 17 is within the measurement range. If it is not within the measurement range, you need to adjust the preamplifier 15 to amplify or reduce the gain;

Step 6: When the temperature of the test piece 28 reaches the set temperature, start timing, and carry out a broadband dual-laser excitation adhesive curing viscosity photothermal characterization test at 0 hours 0h, in which the modulation of the low-power semiconductor laser 35 is set The frequency band range is, and the frequency of the high-power semiconductor laser power supply 6 is 0Hz and the power is 45W;

Step 7: Then conduct a broadband dual-laser excitation photothermal characterization test of the cured viscosity of the adhesive every 1 hour, and then determine whether it is the best bonding time based on the hand touch of the worker, and record the photothermal response characteristic data. Record 0-5 hours;

Step 8: After the 5-hour test data is completed, a dual-laser excitation-induced thermal radiation signal response model needs to be established based on the characteristics of the test piece to achieve a quantitative assessment of the degree of curing;

Step 9: At the end of the test, save the broadband scanning results and fitting results obtained from the test. At the same time, the computer 1 controls the high-power semiconductor laser power supply 6 and the low-power semiconductor laser 35 so that the light intensity becomes 0, and controls the two-axis driver at the same time. 33. Return the two-dimensional micro-displacement moving stage 30 to zero and turn off the heating function of the thermostatic box 29;

Step 10: After the test, after an interval of 5 minutes, turn off the first function generator, high-power semiconductor laser power supply, two-axis driver, preamplifier, HCT thermal detector, second function generator, and phase-locked detection amplifier in order; After the thermostat returns to room temperature, place the test piece into the designated storage container.

Further, the dual laser excitation-induced thermal radiation signal response model for the characteristics of the test piece in step 8 is specifically as follows:

In the formula, K ₁ is the response gain of the HCT thermal detector, k is the thermal conductivity of the test piece, h is the convection heat transfer coefficient existing on the surface of the test piece, α _IR (λ) is the infrared absorption coefficient of the test piece; L ₁ is Thickness of the piece to be tested; σ is the Stefan-Boltzmann constant; β is the light absorption attenuation coefficient of the piece to be tested.

Further, the relationship between the thermal radiation signal of the test piece and the surface temperature signal is as follows:

In the formula, K is the system scale factor; P(λ) is the spectral response frequency band of the HCT thermal detector; ε is the emissivity of the test piece; T ₀ is the room temperature; λ ₁ and λ ₂ are the spectral response ranges of the HCT thermal detector respectively. .

Furthermore, since the signal S(ω) is a complex quantity, the amplitude-frequency and phase-frequency dynamic responses of the photothermal radiation of the test piece under modulation laser action can be directly obtained, that is:

Multi-parameter fitting is to find the best parameters, so that the amplitude and phase information calculated by the mathematical model at the best parameters and the amplitude and phase information obtained through experiments are brought into the objective function G, so that G reaches the minimum value.

Further, the objective function of the multi-parameter fitting is,

In the formula, Z ₁ and Z ₂ are scaling factors; g is the coefficient to be fitted (including thermal conductivity and thermal diffusion coefficient); n is the number of collection points; f _i is the modulation frequency; Ampl ^T and Phase ^T are the calculated amplitudes. and phase; Ampl ^E , Phase ^E are the amplitude and phase characteristic data obtained from the experiment. Figure 3 shows the broadband thermal radiation response test results of solid engine nozzle adhesive samples at different curing times. Figure 4 is drawn by analyzing the characteristic results of different curing times of solid engine nozzle adhesive samples at specific frequencies. It can be clearly seen from Figure 4 that the optimal curing time is around 3 hours. This mathematical model is used to solve the range problem of the obtained experimental data. Figure 5 shows the fitting results of the experimental values. Based on the fitting results, the specific values of thermal conductivity and thermal diffusion coefficient can be obtained (as shown in Figure 6), which can be used as a standard for quantitative evaluation of curing time.

Claims (7)

1. A photothermal characterization device for solid engine nozzle adhesive solidified viscosity based on broadband dual laser excitation, characterized in that the characterization device includes a computer (1), a first function generator (4), a high-power Semiconductor laser power supply (6), high-power semiconductor laser (9), TEC semiconductor refrigerator (10), TEC refrigerator power supply (11), first mounting bracket (13), large off-axis parabolic mirror (14), front amplifier (15), HCT thermal detector (17), first polarizer (18), bandpass filter (19), first collimator (20), first engineering diffuser (21), Two polarizers (22), second collimator (23), second engineered diffuser (24), third polarizer (25), focusing film (26), small off-axis parabolic lens (27), and Test piece (28), thermostat (29), two-dimensional micro-displacement moving stage (30), second mounting support (32), two-axis driver (33), low-power semiconductor laser (35), second function generator Detector (37), phase-locked detection amplifier (39), drive control line (41); The computer (1) is connected to the first function generator (4) and the high-power semiconductor laser power supply (6) in sequence, and the high-power semiconductor laser power supply (6) is connected to the high-power semiconductor laser (9) and the TEC refrigerator power supply respectively. (11) are connected to each other, a TEC semiconductor refrigerator (10) is installed on the TEC refrigerator power supply (11), and the high-power semiconductor laser (9) is connected to the first collimating mirror (20) and the first engineering diffuser in sequence. body (21) and the second polarizing plate (22); The computer (1) is also connected to a lock-in detection amplifier (39), which is connected in sequence to a preamplifier (15), an HCT thermal detector (17), and a first polarizing plate (18). ) and a bandpass filter (19); the bandpass filter (19) is used with a large off-axis parabolic mirror (14), which is arranged on the first mounting support (13) superior; The phase-locked detection amplifier (39) is also connected to a second function generator (37), which is connected in turn to a low-power semiconductor laser (35) and a second collimating mirror (23). , the second engineering diffuser (24), the third polarizing plate (25) and the focusing plate (26), the second engineering diffuser (24), the third polarizing plate (25) and the focusing plate (26) Embedded into the designated installation position of the small off-axis parabolic mirror (27), which is provided on the second mounting support (32); The computer (1) is also connected to a two-axis driver (33). The two-axis driver (33) is connected to a two-dimensional micro-displacement moving stage (30). On the two-dimensional micro-displacement moving stage (30) A constant temperature box (29) is provided, and the piece to be tested (28) is placed in the constant temperature box (29). 2. A photothermal characterization device for solid engine nozzle adhesive cured viscosity based on broadband dual laser excitation according to claim 1, characterized in that the computer (1) is provided with 2 output signal terminals and 1 input/output signal terminal, the computer (1) is connected to the phase-locked detector amplifier (39) through the input/output signal terminal Ethernet cable (40), the computer (1) passes the first output signal terminal first B-type USB data The line (3) is connected to the input signal end of the first function generator (4); the computer (1) drives the control line (41) and is connected to the two-axis driver (33) through the second output signal end; the phase-locked detection amplifier ( The output signal end of 39) is connected to the second function generator (37) through the second BNC data line (38); the input signal end of the phase-locked detection amplifier (39) is connected to the front signal through a high-performance radio frequency coaxial cable (2). The second function generator (37) is connected to the low-power semiconductor laser (35) through the second B-type USB data line (36), and the laser emitted by the low-power semiconductor laser (35) passes through the second The laser fiber (34) is transmitted to the second collimating mirror (23); The second engineering diffuser (24), the third polarizing plate (25) and the focusing plate (26) are embedded in the designated installation position of the small off-axis parabolic mirror (27); the test piece (28) is placed in the thermostat (29) ), the thermostatic box (29) is placed on the two-dimensional micro-displacement moving stage (30), which has realized the position scanning detection of the test piece (28); the small off-axis parabolic mirror (27) is installed on the second installation On the support (32), the large off-axis parabolic mirror (14) is installed on the first installation support (13); the HCT thermal detector (17) is input to the preamplifier (15) through the coaxial cable (16) The signal ends are connected to achieve amplification of the photothermal signal; the bandpass filter (19) and the first polarizer (18) are fixed in front of the HCT thermal detector (17) through threaded connections, and the bandpass filter (19) achieves Effective filtering of near-infrared excitation light; the output signal end of the first function generator (4) is connected to the high-power semiconductor laser power supply (6) through the first BNC data line (5); the high-power semiconductor laser power supply (6) It is connected to the high-power semiconductor laser (9) and TEC refrigerator power supply (11) through the semiconductor laser power supply line (7) and the TEC refrigerator power supply line (8) respectively, and the TEC semiconductor refrigerator (10) is located in the high-power semiconductor laser (10). 9) and between the TEC refrigerator power supply (11); the high-power semiconductor laser (9) transmits the laser to the first collimating mirror (20) through the first laser fiber (12), respectively in front of the first collimating mirror (20) A first engineering diffuser (21) and a second polarizer (22) are installed. 3. A photothermal characterization method of solid engine nozzle adhesive curing viscosity based on broadband dual laser excitation according to claim 1 or 2, characterized in that the characterization method includes the following steps: Step 1: Identify the piece to be tested (28), place the piece to be tested in the thermostat (29), open the thermostat (29), and set the temperature to 80°C; Step 2: Turn on the photothermal characterization device for solid engine nozzle adhesive cured viscosity based on broadband dual laser excitation; Step 3: Adjust the position of the two-dimensional micro-displacement moving stage (30) so that the test piece (28) is at the focus position of the small off-axis parabolic mirror (27). At the same time, adjust the first installation support (13) to make the HCT hot. The element detected by the detector (17) is at the focal position of the large off-axis parabolic mirror (14); Step 4: The computer (1) issues an instruction to make the low-power semiconductor laser (35) generate a laser with a modulation frequency of 0Hz through the lock-in detection amplifier (39) and the second function generator (37). At this time, check whether the laser spot size is normal; At the same time, the computer (1) issues instructions to cause the high-power semiconductor laser power supply (6) to generate laser light with a modulation frequency of 0 Hz through the first function generator (4). At this time, check whether the laser light emitted by the first collimating mirror (20) is completely Cover the item under test (28); Step 5: Observe whether the signal obtained from the HCT thermal detector (17) by the lock-in detection amplifier (39) is within the measurement range. If it is not within the measurement range, you need to adjust the preamplifier (15) to amplify or reduce the gain; Step 6: When the temperature of the test piece (28) reaches the set temperature, start timing, and carry out a broadband dual-laser excitation adhesive curing viscosity photothermal characterization test at 0 hours (0h), in which the low-power semiconductor is set The modulation frequency band range of the laser (35) is, and the frequency of the high-power semiconductor laser power supply (6) is 0Hz and the power is 45W; Step 7: Then conduct a broadband dual-laser excitation photothermal characterization test of the cured viscosity of the adhesive every 1 hour, and then determine whether it is the best bonding time based on the hand touch of the worker, and record the photothermal response characteristic data. Record 0-5 hours; Step 8: After the 5-hour test data is completed, a dual-laser excitation-induced thermal radiation signal response model needs to be established based on the characteristics of the test piece (28) to achieve a quantitative evaluation of the degree of curing; Step 9: At the end of the test, save the broadband scanning results and fitting results obtained from the test, and at the same time, the computer (1) controls the high-power semiconductor laser power supply (6) and the low-power semiconductor laser (35) to make the light intensity become 0 , simultaneously control the two-axis driver (33) to return the two-dimensional micro-displacement moving stage (30) to zero and turn off the heating function of the thermostatic box (29); Step 10: After the test, after an interval of 5 minutes, turn off the first function generator (4), high-power semiconductor laser power supply (6), two-axis driver (33), preamplifier (15), and HCT thermal detector in order (17), the second function generator (37) and the lock-in detection amplifier (39); after the thermostat (29) returns to room temperature, the test piece (28) is placed in a designated storage container. 4. A photothermal characterization method of solid engine nozzle adhesive curing viscosity based on broadband dual laser excitation according to claim 3, characterized in that in step eight, the characteristics of the test piece are established to induce heat induced by dual laser excitation. The radiation signal response model is specifically, In the formula, K ₁ is the response gain of the HCT thermal detector, k is the thermal conductivity of the test piece, h is the convection heat transfer coefficient existing on the surface of the test piece, α _IR (λ) is the infrared absorption coefficient of the test piece; L ₁ is Thickness of the piece to be tested; σ is the Stefan-Boltzmann constant; β is the light absorption attenuation coefficient of the piece to be tested. 5. A photothermal characterization method of solid engine nozzle adhesive solidified viscosity based on broadband dual laser excitation according to claim 4, characterized in that the relationship between the thermal radiation signal of the test piece and the surface temperature signal is as follows , In the formula, K is the system scale factor; P(λ) is the spectral response frequency band of the HCT thermal detector; ε is the emissivity of the test piece; T ₀ is the room temperature; λ ₁ and λ ₂ are the spectral response ranges of the HCT thermal detector respectively. . 6. A photothermal characterization method of solid engine nozzle adhesive solidified viscosity based on broadband dual laser excitation according to claim 5, characterized in that since the signal S(ω) is a complex quantity, it can be directly modulated The dynamic response of the amplitude frequency and phase frequency of the photothermal radiation of the test piece under laser action, that is: Multi-parameter fitting is to find the best parameters, so that the amplitude and phase information calculated by the mathematical model at the best parameters and the amplitude and phase information obtained through experiments are brought into the objective function G, so that G reaches the minimum value. 7. A photothermal characterization method of solid engine nozzle adhesive solidified viscosity based on broadband dual laser excitation according to claim 6, characterized in that the objective function of the multi-parameter fitting is, In the formula, Z ₁ and Z ₂ are scaling factors; g is the coefficient to be fitted; n is the number of collection points; _fi is the modulation frequency; Ampl ^T and Phase ^T are the calculated amplitude and phase; Ampl ^E and Phase ^E are the tests. Obtained amplitude and phase characteristic data.