Pressure-sensitive coating suitable for ultralow oxygen content and extreme cryogenic environment and preparation process flow of pressure-sensitive coating

Abstract

The invention relates to a pressure-sensitive coating suitable for ultralow oxygen content and extreme cryogenic environment and a preparation process flow of the pressure-sensitive coating. The pressure-sensitive coating of the present invention comprises: a porous adhesive layer formed from poly (1-trimethylsilyl-1-propyne) as an adhesive; and PdTFPP or PtTFPP formed in the pores as a luminescent probe, wherein the thickness of the adhesive layer is 5-20 [mu] m. The pressure-sensitive coating disclosed by the invention can have high sensitivity in an ultra-low oxygen content and extreme cryogenic environment. The preparation process flow provided by the invention has a standardized flow, can be used for preparing the high-stability coating and is easy to operate.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical pressure measurement, and in particular, relates to a low-temperature pressure-sensitive paint (PSP) and a preparation process thereof. Background Art

[0002] Pressure-Sensitive Paint (PSP) is an important means for wind tunnel evaluation of large aircraft boundary layer / shock wave interference characteristics and aerodynamic load characteristics under flight Reynolds number conditions. Compared with traditional aircraft surface pressure measurement methods, non-contact measurement methods based on pressure-sensitive paint can obtain high-resolution continuous pressure distribution maps of the entire aircraft surface. At the same time, it also greatly reduces the cost and workload of sensor layout and installation, and the model making and test cycle are also significantly shortened. The economy and timeliness are significantly improved, and it has excellent applicability. However, under extreme conditions, such as ultra-low oxygen content or extremely cold environments, the traditional PSP has a significantly lower pressure sensitivity than the PSP used under normal conditions due to the greatly reduced oxygen permeability of the polymer adhesive that forms the coating.

[0003] In order to realize the application of PSP technology in extreme conditions such as low-temperature wind tunnels, since the 1990s, NASA, DLR, JAXA and other institutions have continued to conduct research on basic scientific issues and experimental applications of low-temperature PSP. However, the performance of pressure-sensitive coatings known to be suitable for ultra-low oxygen content and extreme deep cold environments needs to be improved, and the spraying process of low-temperature pressure-sensitive coatings lacks standardized processes. The factors that affect the performance of pressure-sensitive coatings are very complex. Probe concentration, coating thickness, curing temperature, solvent type, etc. may affect the final performance of the coating. Summary of the invention

[0004] An object of the present invention is to provide a low-temperature pressure-sensitive coating having high sensitivity in ultra-low oxygen content and extreme deep cold environments.

[0005] Another object of the present invention is to provide a method for preparing a low-temperature pressure-sensitive coating which has a standardized process, can produce a coating with high stability and is easy to operate.

[0006] In order to achieve the above-mentioned purpose of the present invention, the present invention adopts the following technical solutions:

[0007] The present invention provides a low-temperature pressure-sensitive coating, comprising: a porous binder layer formed by poly(1-trimethylsilyl-1-propyne) (PTMSP) as a binder, and palladium tetrakis(pentafluorophenyl) porphyrin (PdTFPP) or platinum tetrakis(pentafluorophenyl) porphyrin (PtTFPP) formed in the pores as a luminescent probe.

[0008] In a specific embodiment, the thickness of the binder layer can be 5-20 μm, preferably 6-10 μm.

[0009] In a specific embodiment, the weight ratio of the luminescent probe to the binder is 0.1-0.5.

[0010] The present invention provides a preparation process for a low-temperature pressure-sensitive coating, comprising the following steps:

[0011] (1) Surface pretreatment of the model: The surface of the model to be measured is polished or ground, and then the surface of the model is cleaned with anhydrous ethanol.

[0012] (2) Preparation of the binder solution: Poly(1-trimethylsilyl-1-propyne) (PTMSP) as a binder is dissolved in a solvent at a ratio of 3-7 mg / ml, and stirred until completely dissolved to obtain a binder solution.

[0013] (3) Spraying of the binder solution: The binder solution is sprayed from one side of the surface of the model to the other side, and reciprocated for 10-30 cycles to uniformly spray the binder solution on the surface of the model.

[0014] (4) Formation of the binder layer: The model sprayed with the binder is placed in a dark, dry, normal temperature and pressure environment until the solvent completely volatilizes, and the binder cures to form a model with a porous binder layer, and the thickness of the binder layer is 5-20 μm.

[0015] (5) Preparation of the probe solution: The probe is dissolved in the solvent at a ratio of 0.5-2 mg / ml, and stirred until completely dissolved to obtain a probe solution.

[0016] (6) Spraying of the probe solution: In the same manner as in step (3), but with a spraying pressure lower than that in step (3), the probe solution is sprayed from one side of the surface of the model to the other side, and reciprocated for 5-25 cycles to uniformly spray the probe solution on the surface of the model with the binder layer.

[0017] (7) Formation of the low-temperature pressure-sensitive coating: Place the model sprayed with the probe solution in a dark, dry environment at normal temperature and pressure until the solvent has completely evaporated. The probe is formed in the pores of the adhesive layer, and the low-temperature pressure-sensitive coating of the present invention is prepared.

[0018] In a specific embodiment, in step (2), the solvent can be toluene or ethanol.

[0019] In a specific embodiment, in step (2), stirring can be carried out for 8 to 24 hours.

[0020] In a specific embodiment, in step (3),

[0021] The spraying equipment used for spraying can include an air compressor, a spray gun, a model fixing device, a pressure reducing valve, a viscometer, or a coating thickness gauge, etc.;

[0022] The spraying pressure can be 0.2 - 0.4 MPa;

[0023] The flow rate of the spray gun can be 0.05 - 0.15 L / min;

[0024] The distance between the spray gun and the model or sample piece can be 15 - 25 cm;

[0025] The ambient temperature can be 20 - 30 °C, and the humidity ≤ 60%.

[0026] Thus, it can be ensured that during the spraying process, the PSP is evenly sprayed on the surface of the model.

[0027] In a specific embodiment, in step (4), the placement time can be 12 - 24 hours.

[0028] In a specific embodiment, in step (5), the probe can be PdTFPP or PtTFPP.

[0029] In a specific embodiment, in step (5), the solvent can be toluene or ethanol.

[0030] In a specific embodiment, in step (5), stirring can be carried out for 5 - 15 minutes.

[0031] In a specific embodiment, in step (6), due to the different viscosities of the probe solution and the PTMSP solution, the spraying pressure of the probe solution can be 0.15 - 0.25 MPa.

[0032] In a specific embodiment, in step (7), the placement time can be 4 - 6 hours.

[0033] Compared with the prior art, the advantages of the present invention are:

[0034] The present invention prepares a cryogenic pressure-sensitive coating applicable to ultra-low oxygen content and extremely cryogenic environments by selecting appropriate adhesives and probe molecules and forming a porous adhesive layer and probes formed in the pores respectively in a specific ratio and order (as Figure 5 shown). The cryogenic pressure-sensitive coating of the present invention uses porphyrin-based oxygen-sensing probes PdTFPP or PtTFPP as core components, improving key properties such as the luminescence intensity, temperature-sensitive characteristics, and pressure-sensitive characteristics of the cryogenic pressure-sensitive coating. In addition, the cryogenic pressure-sensitive coating of the present invention uses a polymer adhesive PTMSP with high oxygen permeability as the adhesive. On the one hand, it can bond the luminescent probe to the surface of the model to prevent the shedding of the luminescent probe when used under extreme conditions such as in an ETW wind tunnel; on the other hand, due to the high oxygen permeability of PTMSP, the pressure sensitivity of the cryogenic pressure-sensitive coating of the present invention is improved.

[0035] The present invention provides a standardized spraying process for the cryogenic pressure-sensitive coating layer, that is, it standardizes influencing factors such as the coating thickness, spraying order, probe concentration, and solvent type during the coating spraying process, so that a highly stable coating can be prepared. The preparation method of the cryogenic pressure-sensitive coating of the present invention is convenient and easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Shows the pressure sensitivity curves of the cryogenic pressure-sensitive coating prepared in Example 1 at different temperatures;

[0037] Figure 2 Shows the pressure sensitivity curves of the cryogenic pressure-sensitive coating with adhesive layers of different thicknesses prepared in Example 2;

[0038] Figure 3 Shows the pressure sensitivity curves of the cryogenic pressure-sensitive coating prepared in Example 3 with different spraying orders;

[0039] Figure 4 Shows the pressure sensitivity curves of the cryogenic pressure-sensitive coating prepared in Example 4 with different solvents at different temperatures; where, (a) 298K; (b) 273K; (c) 248K; (d) 223K;

[0040] Figure 5 Is a schematic structural diagram of the cryogenic pressure-sensitive coating of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0041] Example 1:

[0042] The surface of the model to be measured (a 50 mm × 8 mm stainless steel strip) is polished, and then the surface of the model is cleaned with absolute ethanol.

[0043] Poly(1-trimethylsilyl-1-propyne) (PTMSP) was dissolved in toluene at a ratio of 5 mg / ml and stirred for 12 hours to completely dissolve it, obtaining a PTMSP solution. At 25 °C and a humidity ≤ 60%, using a spray gun, under the conditions of a spraying pressure of 0.35 MPa, a spray gun flow rate of 0.08 L / min, and a spray gun distance from the model of 15 cm, the PTMSP solution was sprayed from one side of the surface of the stainless-steel strip to the other side, and this was reciprocated for 25 cycles to evenly spray the PTMSP solution on the surface of the model. Subsequently, the model sprayed with PTMSP was placed in a dark, dry, normal temperature and pressure environment. After 12 hours, the solvent completely volatilized, and PTMSP solidified to form a model with a porous PTMSP layer having a thickness of 8 μm.

[0044] The probe PtTFPP was dissolved in toluene at a ratio of 1.2 mg / ml and stirred for 10 minutes to completely dissolve it, obtaining a probe solution. In the same manner as described above, but with a spraying pressure of 0.25 MPa and sprayed for 15 cycles to evenly spray the probe solution on the surface of the model with a PTMSP layer. Subsequently, the model sprayed with the probe solution was placed in a dark, dry, normal temperature and pressure environment. After 5 hours, the solvent completely volatilized, and the probe formed in the pores of the PTMSP layer, where the weight ratio of the luminescent probe to the binder was 0.25, obtaining the low-temperature pressure-sensitive coating of the present invention.

[0045] The prepared low-temperature pressure-sensitive coating was subjected to a pressure sensitivity test at an oxygen concentration of 2000 ppm and different temperatures (i.e., 298 K, 273 K, 248 K, 223 K, 198 K, 173 K, 148 K, and 123 K), and the measurement results are as Figure 1 shown.

[0046] As Figure 1 shown, at 298 K, the pressure sensitivity of the coating was 0.498% / kPa, at 273 K, the pressure sensitivity of the coating was 0.497% / kPa, at 248 K, the pressure sensitivity of the coating was 0.487% / kPa, at 223 K, the pressure sensitivity of the coating was 0.475% / kPa, at 198 K, the pressure sensitivity of the coating was 0.451 / kPa, at 173 K, the pressure sensitivity of the coating was 0.40 / kPa, at 148 K, the pressure sensitivity of the coating was 0.337 / kPa. In particular, the coating still had a pressure sensitivity of 0.29% / kPa in an environment of minus 150 °C (123 K).

[0047] It can be seen therefrom that the properties of the low-temperature pressure-sensitive coating of the present invention have been greatly improved, and it can basically meet the experimental requirements under extreme conditions such as low-temperature high Reynolds number wind tunnels.

[0048] Example 2:

[0049] The surface of the model to be tested (5 stainless steel strips of 50 mm×8 mm) was polished, and then the surface of the model was cleaned with absolute ethanol.

[0050] Poly(1-trimethylsilyl-1-propyne) (PTMSP) was dissolved in toluene at a ratio of 3 mg / ml and stirred for 10 hours to completely dissolve it, obtaining a PTMSP solution. At 20 °C and a humidity ≤60%, using a spray gun, under the conditions that the spraying pressure was 0.33 MPa, the flow rate of the spray gun was 0.05 L / min, and the distance between the spray gun and the model was 20 cm, the PTMSP solution was sprayed from one side of the surface of the stainless steel strip to the other side, and 10, 15, 20, 25, 30 cycles were carried out reciprocally to uniformly spray the PTMSP solution on the surface of the model. Subsequently, the model sprayed with PTMSP was placed in a dark, dry, normal temperature and pressure environment. After 12 hours, the solvent volatilized completely, and PTMSP was cured to form a model with PTMSP layers of porous thicknesses of 2 μm, 4 μm, 6 μm, 8 μm, and 10 μm in sequence.

[0051] The probe PtTFPP was dissolved in toluene at a ratio of 0.7 mg / ml and stirred for 8 minutes to completely dissolve it, obtaining a probe solution. In the same manner as described above, but the spraying pressure was 0.25 MPa and sprayed for 12 cycles to uniformly spray the probe solution on the surface of the model with a PTMSP layer. Subsequently, the model sprayed with the probe solution was placed in a dark, dry, normal temperature and pressure environment. After 5 hours, the solvent volatilized completely, and the probe was formed in the pores of the PTMSP layer, where the weight ratio of the luminescent probe to the binder was 0.1, obtaining the low-temperature pressure-sensitive coating of the present invention.

[0052] By adopting the above spraying process, the five groups of low-temperature pressure-sensitive coatings prepared were obtained by simultaneous spraying, and other variables were the same except for the thickness of the binder layer.

[0053] The low-temperature pressure-sensitive coatings with binder layers of different thicknesses prepared were subjected to pressure sensitivity tests at 298 K, and the measurement results are as Figure 2 shown.

[0054] From Figure 2The results show that when the thickness of the adhesive layer is 2 μm, the pressure sensitivity of the coating is almost lost; when the thickness of the adhesive layer is 4 μm, the pressure sensitivity of the coating is 0.172% / kPa, which is significantly lower; when the thickness of the adhesive layer is 6 - 10 μm, the pressure sensitivities of the coating are 0.379% / kPa, 0.389% / kPa, and 0.396% / kPa respectively, that is, the pressure sensitivity of the coating is very high. It can be clearly seen that as the thickness of the adhesive layer increases, the pressure sensitivity of the coating gradually increases, and after 6 μm, the change in pressure sensitivity caused by the thickness is relatively small.

[0055] Example 3:

[0056] According to the method in Example 1, but with different spraying sequences, two groups of low-temperature pressure-sensitive coatings were prepared respectively.

[0057] The first group was sprayed with only PTMSP, and after the PTMSP was cured, the probe PtTFPP was sprayed; the second group was prepared by simultaneously preparing the PTMSP and probe PtTFPP solutions, mixing them, and spraying them on the surface of the sample at the same time. Then, they were placed in the same storage environment, and after experiencing the same curing time, they were simultaneously put into the calibration chamber for synchronous calibration.

[0058] Figure 3 The results respectively show the calibration results at 24 h and 72 h of the low-temperature pressure-sensitive coatings prepared by two different spraying sequences. It can be seen from the figure that after the two groups of samples were placed in the calibration chamber for the same time (72 hours), the pressure sensitivity attenuation of the sample in which the probe PtTFPP and PTMSP were simultaneously dissolved in toluene and sprayed was greater, while the reproducibility of the sample in which they were separately dissolved in toluene and sprayed was better, and the pressure sensitivity attenuation was smaller.

[0059] Example 4:

[0060] According to the method in Example 2, but using toluene and ethanol as solvents respectively, the low-temperature pressure-sensitive coating of the present invention was prepared.

[0061] The pressure sensitivity curves of the low-temperature pressure-sensitive coating at different temperatures, namely, (a) 298K; (b) 273K; (c) 248K; (d) 223K were measured, and the results are as Figure 4 shown.

[0062] As Figure 4 It can be seen that compared with using toluene as the solvent, the pressure sensitivity curves of the low-temperature pressure-sensitive coating prepared using ethanol as the solvent show better consistency at 298K, 273K, 248K, and 223K.

[0063] By the method for preparing a low-temperature pressure-sensitive coating with a standardized process and easy operation of the present invention, a coating with high stability can be obtained. This low-temperature pressure-sensitive coating of the present invention can have high pressure sensitivity under an ultra-low oxygen content and an extremely cryogenic environment.

Claims

1. A pressure-sensitive coating applicable to an ultra-low oxygen content and an extremely cryogenic environment, comprising: A porous adhesive layer formed of poly(1-trimethylsilyl-1-propyne) as an adhesive, and palladium tetrakis(pentafluorophenyl)porphyrin or platinum tetrakis(pentafluorophenyl)porphyrin formed as a luminescent probe in the pores, wherein the thickness of the adhesive layer is 5-20 μm.

2. The pressure-sensitive paint according to claim 1, wherein the thickness of the adhesive layer is 6-10 μm.

3. The pressure-sensitive paint according to claim 1, wherein the weight ratio of the luminescent probe to the adhesive is 0.1 to 0.

5.

4. A preparation process flow of a pressure-sensitive paint applicable to an ultra-low oxygen content and an extremely cryogenic environment, comprising the following steps: (1) Surface pretreatment of the model: The surface of the model to be measured is polished or ground, and then the surface of the model is cleaned with anhydrous ethanol; (2) Preparation of the adhesive solution: Poly(1-trimethylsilyl-1-propyne) as an adhesive is dissolved in a solvent at a ratio of 3-7 mg / ml, and stirred until completely dissolved to obtain an adhesive solution; (3) Spraying of the adhesive solution: The adhesive solution is sprayed from one side of the surface of the model to the other side, and reciprocated for 10-30 cycles to uniformly spray the adhesive solution on the surface of the model; (4) Formation of the adhesive layer: The model sprayed with the adhesive is placed in a dark and dry environment at normal temperature and pressure until the solvent completely volatilizes, and the adhesive cures to form a model with a porous adhesive layer, and the thickness of the adhesive layer is 5-20 μm; (5) Preparation of the probe solution: The probe is dissolved in the solvent at a ratio of 0.5-2 mg / ml, and stirred until completely dissolved to obtain a probe solution; (6) Spraying of the probe solution: In the same manner as in step (3), but with a spraying pressure lower than that in step (3), the probe solution is sprayed from one side of the surface of the model to the other side, and reciprocated for 5-25 cycles to uniformly spray the probe solution on the surface of the model with the adhesive layer; (7) Formation of the cryogenic pressure-sensitive paint: The model sprayed with the probe solution is placed in a dark and dry environment at normal temperature and pressure until the solvent completely volatilizes, and the probe is formed in the pores of the adhesive layer to obtain the cryogenic pressure-sensitive paint of the present invention.

5. According to the preparation process flow of claim 4, wherein in step (2), the solvent can be toluene or ethanol; the stirring time is 8-24 hours.

6. According to the preparation process flow of claim 4, wherein in step (3), the spraying equipment used for spraying includes an air compressor, a spray gun, a model fixing device, a pressure reducing valve, a viscometer, or a coating thickness gauge; the spraying pressure is 0.2-0.4 MPa; the flow rate of the spray gun is 0.05-0.15 L / min; the distance between the spray gun and the model is 15-25 cm.

7. According to the preparation process flow of claim 4, wherein in step (4), the placement time is 12-24 hours.

8. According to the preparation process flow described in claim 4, wherein in step (5), the probe is palladium tetrakis(pentafluorophenyl)porphyrin or platinum tetrakis(pentafluorophenyl)porphyrin; the solvent is toluene or ethanol; the stirring time is 5 to 15 minutes.

9. According to the preparation process flow described in claim 5, wherein in step (6), the spraying pressure is 0.15 to 0.25 MPa.

10. According to the preparation process flow described in claim 5, wherein in step (7), the placement time is 4 to 6 hours.

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