A high-temperature-resistant radar wave-absorbing coating material for repairing and a preparation method thereof

Abstract

This invention belongs to the technical field of high-temperature radar absorbing coating materials, specifically disclosing a high-temperature resistant radar absorbing coating material for repair and its preparation method. The coating material includes a radar bonding layer and a radar absorbing layer, and its preparation includes the following steps: 1) substrate pretreatment; 2) preparation of the radar bonding layer; 3) preparation of the radar absorbing layer coating; 4) preparation of the coating material; wherein, the coating material is prepared by weighing a mixture of Al2O3 powder and FeCr in a mass ratio of 1:1:1:(2.5-3.5). 21 Al4 powder, CaTi 0.05 Mn 0.95 O3 powder and inorganic salt binder are mixed evenly. During coating material preparation, the coating is uniformly sprayed onto the radar bonding layer using air spraying technology and then cured. The high-temperature resistant radar absorbing coating material prepared by this invention has excellent absorption performance, mechanical properties, and thermal shock resistance. Furthermore, the air spraying technology and low-temperature curing process used in its preparation enable on-site repair of damaged coatings.

Description

Technical Field

[0001] This invention belongs to the technical field of high-temperature radar absorbing coating materials, specifically relating to a high-temperature resistant radar absorbing coating material for repair and its preparation method, mainly used for repairing weapons and equipment with operating temperatures of 550℃~650℃. Background Technology

[0002] Radar-absorbing coatings are stealth materials that can attenuate incident electromagnetic waves, converting their electromagnetic energy into heat energy for dissipation or causing the electromagnetic waves to disappear due to interference. They are widely used in military, aviation, aerospace, communications, and electronics fields, for example, for the stealth of weapons such as fighter jets and supersonic cruise missiles. In recent years, with the rapid development of radar detection technology, which has posed a significant threat to weaponry, countries are making every effort to develop radar stealth technology to improve the survivability of their equipment. High-temperature broadband radar-absorbing coatings are a key focus of research, as the operating temperatures of components such as engine exhaust nozzles, missile nose cones, and tank exhaust pipes reach around 600℃. Existing high-temperature ceramic-based radar-absorbing coatings have been successfully applied to high-temperature components of weaponry. However, due to the complex and harsh service environment of these coatings, they are prone to localized small-area damage under prolonged airflow erosion and high / low temperature impacts, affecting the overall radar-absorbing performance, mechanical properties, and appearance. However, disassembling parts with small-area coating damage and re-preparing new coatings is not only a complex process, but also wasteful of materials and time. Therefore, on-site rapid repair technology for radar absorbing coatings has become particularly important.

[0003] Currently, high-temperature absorbing coatings successfully applied to weapon components are mainly prepared using plasma spraying technology. While coatings prepared using this technology possess excellent mechanical properties and environmental resistance, they are not suitable for field repair. To repair damaged areas of the coating without disassembling components, air spraying technology and low-temperature curing processes have attracted significant attention due to their advantages, such as simple and portable spraying equipment, stable and controllable processes, and the fact that the coating preparation process is not limited by the external environment.

[0004] In view of this, this invention is hereby proposed. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a high-temperature resistant radar absorbing coating material for repair and its preparation method. This invention mainly utilizes air spraying technology and low-temperature curing process to achieve on-site repair of damaged coatings, and the repaired coating material has excellent radar absorption performance, mechanical properties and thermal shock resistance.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] On one hand, the present invention provides a high-temperature resistant radar absorbing coating material for repair, comprising a radar adhesive layer and a radar absorbing layer, wherein the radar adhesive layer is sprayed onto the metal substrate to be repaired after sandblasting, and the radar absorbing layer is sprayed onto the radar adhesive layer and cured to form a high-temperature resistant radar absorbing coating material.

[0008] The radar absorbing layer includes Al2O3 powder and FeCr. 21 Al4 powder, CaTi 0.05 Mn 0.95 O3 powder and inorganic salt binder, and the Al2O3 powder and FeCr 21 Al4 powder, CaTi 0.05 Mn 0.95 The mass ratio of O3 powder to inorganic salt binder is 1:1:1:(2.5~3.5).

[0009] Furthermore, the thickness of the radar adhesive layer is (100±15)μm; the thickness of the high-temperature resistant radar absorbing coating material is 1.0mm~1.2mm.

[0010] On the other hand, the present invention provides a method for preparing the above-mentioned high-temperature resistant radar absorbing coating material for repair, specifically including the following steps:

[0011] Step 1: Substrate pretreatment: Sandblast the metal substrate to be repaired to remove oxides and impurities from its surface.

[0012] Step 2: Prepare the radar bonding layer: Spray the radar bonding layer onto the sandblasted metal substrate to be repaired.

[0013] Step 3: Preparation of radar absorbing layer coating: Weigh the mixed Al2O3 powder and FeCr according to a mass ratio of 1:1:1:(2.5~3.5). 21 Al4 powder, CaTi 0.05 Mn 0.95 O3 powder and inorganic salt binder are mixed evenly to obtain radar absorbing layer coating;

[0014] Step 4: Prepare coating material: Use air spraying technology to uniformly spray the radar absorbing layer coating obtained in step 3 onto the radar bonding layer prepared in step 2, and then cure it to form a high-temperature resistant radar absorbing coating material.

[0015] Furthermore, in step one, the roughness of the surface of the metal substrate to be repaired after sandblasting should be 5μm to 15μm, and the flatness of the surface of the metal substrate to be repaired after sandblasting should be ≤1.0mm.

[0016] Furthermore, the mixed Al2O3 powder is formed by mixing Al2O3 powder with a particle size ≤5μm and Al2O3 powder with a particle size of 15μm to 75μm in a mass ratio of 1 to 9: 9 to 1.

[0017] Furthermore, the FeCr 21 The composition and proportion of Al4 powder are: 20.0wt% to 22.0wt% Cr, 3.0wt% to 5.0wt% Al and 73wt% to 77wt% Fe.

[0018] Furthermore, the inorganic salt binder is an aluminum dihydrogen phosphate solution with a solid content of 20wt% to 30wt%.

[0019] Furthermore, the mixed Al2O3 powder and FeCr 21 Al4 powder, CaTi 0.05 Mn 0.95 When mixing O3 powder and inorganic salt binder, first use a spatula to manually stir until there is no sediment, and then use a homogenizer to further mix the microwave absorbing coating until the microwave absorbing coating is evenly mixed.

[0020] The process parameters of the homogenizing disperser when mixing coatings are set as follows: rotation speed is set to 1000 r / min to 1500 r / min, and mixing time is set to 3 min to 5 min.

[0021] Furthermore, in step four, during the preparation of the coating material, air spraying and curing are repeated alternately until the thickness of the high-temperature resistant radar absorbing coating material meets the requirement of 1.0 mm to 1.2 mm. Then, the metal substrate coated with the high-temperature resistant radar absorbing coating material is heat-treated.

[0022] Furthermore, during the air spraying process, the weight gain per spray is 10g to 20g;

[0023] During the curing process, the curing equipment used is a resistance furnace or high-temperature oven with a temperature difference of ≤15℃. The curing process is as follows: first, cure at room temperature for ≥10 minutes until surface dry; then, use the curing equipment to raise the temperature from room temperature to 75℃~85℃ and hold for 8 minutes~12 minutes; then raise the temperature to 140℃~160℃ and hold for 8 minutes~12 minutes; then raise the temperature to 290℃~310℃ and hold for 4 minutes~6 minutes; finally, cool down with the curing equipment to ≤100℃, remove the metal substrate, and allow it to cool naturally to room temperature.

[0024] The heat treatment process is as follows: the cured metal substrate is heated from room temperature to 340℃~360℃ and held for 25min~35min.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The high-temperature resistant radar absorbing coating material provided by this invention consists of two layers: a radar adhesive layer and a radar absorbing layer. The radar adhesive layer is sprayed onto the sandblasted metal substrate to be repaired, and the radar absorbing layer is composed of Al2O3 powder and FeCr... 21 Al4 powder, CaTi 0.05 Mn 0.95 O3 powder and inorganic salt binder are mixed and formed by air spraying and low-temperature curing. Because the ceramic (containing Al2O3) based radar absorbing coating material has good dielectric loss and its coefficient of thermal expansion matches that of titanium alloy, it has excellent adhesion, thermal shock resistance and radar absorption performance when used to repair high-temperature parts of weapon equipment (generally made of titanium alloy). At the same time, the coating material system is a ceramic-alloy system, which has good compatibility with existing ceramic high-temperature radar absorbing coating materials and metal substrates. It is beneficial to repair local damage to existing high-temperature radar absorbing coatings. The repaired coating material has been verified in practice. Under high temperature environment of 550℃~650℃, the coating material does not show abnormal phenomena such as delamination, bulging, cracking or peeling, and its appearance is similar to the original coating and its thermal shock resistance is consistent.

[0027] 2. The method for preparing the high-temperature resistant radar absorbing coating material provided by the present invention first involves sandblasting the damaged area of ​​the original ceramic high-temperature resistant radar absorbing coating material on the metal substrate to be repaired (mainly used for repairing titanium alloy substrates) to remove oxides and impurities, thereby roughening the surface of the metal substrate and increasing the bonding strength with the radar bonding layer and the radar absorbing layer. In addition, the preparation process of the coating material of the present invention mainly consists of air spraying technology + low-temperature curing technology. The preparation process is simple and controllable, so the repair work of the coating damage area can be completed without disassembling weapon equipment parts. Attached Figure Description

[0028] The accompanying drawings are incorporated in and form part of this specification, and together with the description serve to explain the principles of the invention.

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a flowchart of the method for preparing the high-temperature resistant radar absorbing coating material of the present invention;

[0031] Figure 2These are reflection loss curves of different batches of coating materials prepared in Example 3 of the present invention at 550°C; wherein, 1 is the reflection loss curve of the first batch of coating materials; 2 is the reflection loss curve of the second batch of coating materials; and 3 is the reflection loss curve of the third batch of coating materials. Detailed Implementation

[0032] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of apparatuses consistent with some aspects of the invention as detailed in the appended claims.

[0033] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0034] This invention provides a high-temperature resistant radar absorbing coating material for repair. The high-temperature resistant radar absorbing coating material has a two-layer structure: a radar bonding layer and a radar absorbing layer. The radar bonding layer is sprayed onto the sandblasted metal substrate to be repaired, and its thickness is generally (100±15) μm. The radar absorbing layer is sprayed onto the radar bonding layer and cured to form the high-temperature resistant radar absorbing coating material. The total thickness of the high-temperature resistant radar absorbing coating material is 1.0 mm to 1.1 mm. The radar bonding layer mainly includes Ni, Co, Cr, Al, and Y elements, while the radar absorbing layer includes Al2O3 powder and FeCr. 21 Al4 powder, CaTi 0.05 Mn 0.95 O3 powder and inorganic salt binder, and the Al2O3 powder and FeCr 21 Al4 powder, CaTi 0.05 Mn 0.95 The mass ratio of O3 powder to inorganic salt binder is 1:1:1:(2.5~3.5).

[0035] Please see Figure 1 The present invention also provides a method for preparing the above-mentioned high-temperature resistant radar absorbing coating material for repair, specifically including the following steps:

[0036] Step 1: Substrate pretreatment: Sandblast the metal substrate to be repaired to remove oxides and impurities from its surface.

[0037] Step 2: Prepare the radar bonding layer: Spray the radar bonding layer onto the sandblasted metal substrate to be repaired.

[0038] Step 3: Preparation of radar absorbing layer coating: Weigh the mixed Al2O3 powder and FeCr according to a mass ratio of 1:1:1:(2.5~3.5). 21 Al4 powder, CaTi 0.05 Mn 0.95 O3 powder and inorganic salt binder are mixed evenly to obtain radar absorbing layer coating;

[0039] Step 4: Prepare coating material: Use air spraying technology to uniformly spray the radar absorbing layer coating obtained in step 3 onto the radar bonding layer prepared in step 2, and then cure it to form a high-temperature resistant radar absorbing coating material.

[0040] Specifically, in step one, the main task is to sandblast the damaged areas where the original ceramic-based high-temperature radar absorbing coating material has detached. The surface roughness of the metal substrate to be repaired after sandblasting should be 5μm to 15μm, and the flatness of the surface should be ≤1.0mm. The roughness requirement is to increase the bonding strength with the high-temperature radar absorbing coating material and ensure adhesion. The flatness requirement is to ensure that the thickness of the high-temperature radar absorbing coating material adhered to each area is basically consistent during repair.

[0041] In step two, the radar bonding layer is mainly used to match the metal substrate and the radar absorbing layer. Its specific content can be set according to the actual situation. Generally, it mainly includes Ni, Co, Cr, Al and Y elements. It is prepared by spraying technology. During preparation, the non-sprayed areas can be protected with tape in advance. After preparation, its thickness is (100±15)μm.

[0042] In step three, the mixed Al2O3 powder is prepared by mixing Al2O3 powder with a particle size ≤5μm and Al2O3 powder with a particle size of 15μm~75μm in a mass ratio of 1:1; FeCr 21 The composition and ratio of Al4 powder are: 20.0wt%~22.0wt% Cr, 3.0wt%~5.0wt% Al and 73wt%~77wt% Fe, preferably -325 mesh spherical powder; the inorganic salt binder is an aluminum dihydrogen phosphate solution with a solid content of 20wt%~30wt%; when preparing the coating, first use a spatula to manually stir and mix until there is no sediment, and then use a homogenizing disperser to further mix the microwave absorbing coating until the microwave absorbing coating is uniformly mixed. The process parameters of the homogenizing disperser when mixing the coating are set as follows: the speed is set to 1000r / min~1500r / min, and the mixing time is set to 3min~5min.

[0043] In step four, during the preparation of the coating material, air spraying and curing are repeated alternately until the thickness of the high-temperature resistant radar-absorbing coating material meets the requirements of 1.0 mm to 1.2 mm. Then, the metal substrate coated with the high-temperature resistant radar-absorbing coating material is subjected to heat treatment. The specific process is as follows:

[0044] When air spraying, the weight gain per spray is 10g to 20g.

[0045] During curing, the curing equipment used is a resistance furnace or high-temperature oven with a temperature difference of ≤15℃. The curing process is as follows: first, cure at room temperature for ≥10 minutes until surface dry, then use the curing equipment to raise the temperature from room temperature to 75℃~85℃ and hold for 8 minutes~12 minutes, then raise the temperature to 140℃~160℃ and hold for 8 minutes~12 minutes, then raise the temperature to 290℃~310℃ and hold for 4 minutes~6 minutes, and finally cool down with the curing equipment to ≤100℃, then take out the metal substrate and let it cool naturally to room temperature.

[0046] The heat treatment process is as follows: the cured metal substrate is heated from room temperature to 340℃~360℃ and held for 25min~35min.

[0047] To further verify the effectiveness of the high-temperature resistant radar-absorbing coating material of the present invention, the inventors conducted the following specific experiments.

[0048] Example 1

[0049] The metal substrate of the sample to be repaired is a flat titanium alloy substrate with dimensions of Φ25.4mm×4mm. The original coating material of this flat titanium alloy substrate is a ceramic-based high-temperature radar absorbing coating material, which has peeled off and is damaged. The ceramic-alloy system provided by this invention, i.e., the high-temperature radar absorbing coating material, is used to repair the peeled-off and damaged areas. The preparation process is as follows:

[0050] 1) Substrate pretreatment: Place the flat titanium alloy substrate with dimensions of Φ25.4mm×4mm in a sandblasting machine and sandblast the damaged areas. After sandblasting, the surface roughness of the flat titanium alloy substrate should be 10μm and the flatness should be 0.8mm.

[0051] 2) Preparation of radar bonding layer: The radar bonding layer was prepared using existing spraying technology, and its thickness was 95 μm after preparation;

[0052] 3) Preparation of radar absorbing layer coating: Weigh the mixed Al2O3 powder and FeCr according to the mass ratio of 1:1:1:3. 21 Al4 powder, CaTi 0.05 Mn 0.95 O3 powder and inorganic salt binder are mixed evenly to obtain radar absorbing layer coating;

[0053] The mixed Al2O3 powder is composed of Al2O3 powder with a particle size ≤5μm and Al2O3 powder with a particle size of (15~75)μm mixed in a mass ratio of 1:1; FeCr 21Al4 powder is a 325-mesh spherical powder with the following composition and ratio: 21.0 wt% Cr, 4.0 wt% Al, and 75 wt% Fe; the inorganic salt binder is a 25 wt% aluminum dihydrogen phosphate solution; when mixing the coating, first stir manually with a spatula until there is no sediment, then use a homogenizer to further mix the microwave absorbing coating until the coating is uniformly mixed. The process parameters for the homogenizer when mixing the coating are set as follows: rotation speed is set to 1500 r / min, and mixing time is set to 5 min;

[0054] 4) Preparation of coating material: The radar absorbing layer coating obtained in step 3) is uniformly sprayed onto the radar bonding layer prepared in step 2) using air spraying technology and cured to form a high-temperature resistant radar absorbing coating material;

[0055] In the preparation of the coating material, air spraying and curing are repeated alternately until the thickness of the high-temperature resistant radar-absorbing coating material reaches 1.1 mm (flush with the original coating material). Then, the flat titanium alloy substrate coated with the high-temperature resistant radar-absorbing coating material is heat-treated. The specific operation is as follows:

[0056] During air spraying, the weight gain per spray is 15g. During curing, a high-temperature oven with a temperature difference of ≤15℃ is used. The curing process is as follows: first, cure at room temperature for 15 minutes until surface dry, then use the curing equipment to raise the temperature from room temperature to 80℃ and hold for 10 minutes, then raise the temperature to 150℃ and hold for 10 minutes, then raise the temperature to 300℃ and hold for 5 minutes, and finally cool down to 50℃ with the curing equipment, then remove the flat titanium alloy substrate and allow it to cool naturally to room temperature. The heat treatment process is as follows: the cured flat titanium alloy substrate is heated from room temperature to 350℃ and held for 30 minutes.

[0057] Finally, for the three batches of high-temperature radar absorbing coating materials (ceramic-alloy system) prepared in this embodiment of the invention, six samples from each batch were randomly selected, marked, and then subjected to adhesion performance testing using the pull-off method. The testing equipment was a tensile testing machine, and the test results are shown in Table 1 below:

[0058] Table 1

[0059]

[0060]

[0061] Analysis of the test results in Table 1 shows that the multiple batches of radar absorbing coating materials (ceramic-alloy system) prepared in Example 1 of this invention all have excellent adhesion performance, with an adhesion performance ≥10MPa. Furthermore, after comparison with the original ceramic high-temperature radar absorbing coating materials, their appearance is similar and their adhesion performance is consistent.

[0062] Example 2

[0063] The metal substrate of the sample to be repaired is a flat titanium alloy substrate with dimensions of Φ25.4mm×6mm. The original coating material of this flat titanium alloy substrate is a ceramic-based high-temperature radar absorbing coating material, which has peeled off and is damaged. The ceramic-alloy system provided by this invention, i.e., the high-temperature radar absorbing coating material, is used to repair the peeled-off and damaged areas. The preparation process is as follows:

[0064] 1) Substrate pretreatment: Place the flat titanium alloy substrate with dimensions of Φ25.4mm×6mm in a sandblasting machine and sandblast the damaged areas. After sandblasting, the surface roughness of the flat titanium alloy substrate should be 15μm and the flatness should be 0.5mm.

[0065] 2) Preparation of radar bonding layer: The radar bonding layer was prepared using existing spraying technology, and its thickness was 115 μm after preparation;

[0066] 3) Preparation of radar absorbing layer coating: Weigh the mixed Al2O3 powder and FeCr according to the mass ratio of 1:1:1:2.5. 21 Al4 powder, CaTi 0.05 Mn 0.95 O3 powder and inorganic salt binder are mixed evenly to obtain radar absorbing layer coating;

[0067] The mixed Al2O3 powder is composed of Al2O3 powder with a particle size ≤5μm and Al2O3 powder with a particle size of (15~75)μm mixed at a mass ratio of 1:9; FeCr 21 Al4 powder is a 325-mesh spherical powder with the following composition and ratio: 22.0 wt% Cr, 3.0 wt% Al, and 77 wt% Fe; the inorganic salt binder is a 30 wt% aluminum dihydrogen phosphate solution; when mixing the coating, first manually stir with a spatula until there is no sediment, then use a homogenizer to further mix the microwave absorbing coating until it is uniformly mixed. The process parameters for the homogenizer when mixing the coating are set as follows: rotation speed is set to 1000 r / min, and mixing time is set to 5 min;

[0068] 4) Preparation of coating material: The radar absorbing layer coating obtained in step 3) is uniformly sprayed onto the radar bonding layer prepared in step 2) using air spraying technology and cured to form a high-temperature resistant radar absorbing coating material;

[0069] In the preparation of the coating material, air spraying and curing are repeated alternately until the thickness of the high-temperature resistant radar-absorbing coating material reaches 1.0 mm (flush with the original coating material). Then, the flat titanium alloy substrate coated with the high-temperature resistant radar-absorbing coating material is heat-treated. The specific operation is as follows:

[0070] During air spraying, the weight gain per spray is 10g. During curing, a high-temperature oven with a temperature difference of ≤15℃ is used. The curing process is as follows: first, cure at room temperature for 10 minutes until surface dry, then use the curing equipment to raise the temperature from room temperature to 75℃ and hold for 12 minutes, then raise the temperature to 140℃ and hold for 12 minutes, then raise the temperature to 290℃ and hold for 6 minutes, and finally cool down to 60℃ with the curing equipment, then remove the flat titanium alloy substrate and allow it to cool naturally to room temperature. The heat treatment process is as follows: the cured flat titanium alloy substrate is heated from room temperature to 340℃ and held for 35 minutes.

[0071] Finally, the thermal shock resistance of three batches of high-temperature radar absorbing coating materials prepared in the embodiments of the present invention was tested. The testing equipment was a thermal shock furnace. The testing method was to keep the material at (550±10)℃, (600±10)℃, and (650±10)℃ for (5±1) min, and then keep it at room temperature air for (5±1) min as one test. The tests were repeated cyclically and cumulatively. The test results are shown in Table 2 below.

[0072] Table 2

[0073]

[0074] Analysis of the test results in Table 2 shows that the three batches of high-temperature radar absorbing coating materials (ceramic-alloy system) prepared in Example 2 of this invention all have excellent thermal shock resistance. After withstanding 500 thermal shocks at room temperature to 500℃, 200 thermal shocks at room temperature to 550℃, and 100 thermal shocks at room temperature to 600℃, the coating materials did not exhibit any abnormal phenomena such as delamination, bulging, cracking, or peeling. Furthermore, after comparison with the original ceramic-based high-temperature radar absorbing coating materials, their appearance is similar, and their thermal shock resistance is consistent.

[0075] Example 3

[0076] The metal substrate of the sample to be repaired is a flat titanium alloy substrate with dimensions of 180mm × 180mm × 5mm. The original coating material of this flat titanium alloy substrate is a ceramic-based high-temperature radar absorbing coating material, which has peeled off and is damaged. The ceramic-alloy system provided by this invention, i.e., the high-temperature radar absorbing coating material, is used to repair the peeled-off and damaged areas. The preparation process is as follows:

[0077] 1) Substrate pretreatment: Place the flat titanium alloy substrate with dimensions of 180mm×180mm×5mm in a sandblasting machine and sandblast the damaged areas. After sandblasting, the surface roughness of the flat titanium alloy substrate should be 5μm and the flatness should be 1.0mm.

[0078] 2) Preparation of radar bonding layer: The radar bonding layer was prepared using existing spraying technology, and its thickness was 85 μm after preparation;

[0079] 3) Preparation of radar absorbing layer coating: Weigh the mixed Al2O3 powder and FeCr according to the mass ratio of 1:1:1:3.5. 21 Al4 powder, CaTi 0.05 Mn 0.95 O3 powder and inorganic salt binder are mixed evenly to obtain radar absorbing layer coating;

[0080] The mixed Al2O3 powder is composed of Al2O3 powder with a particle size ≤5μm and Al2O3 powder with a particle size of (15~75)μm mixed at a mass ratio of 9:1; FeCr 21 Al4 powder is a 325-mesh spherical powder with the following composition and ratio: 20.0 wt% Cr, 5.0 wt% Al, and 73 wt% Fe; the inorganic salt binder is a 20 wt% aluminum dihydrogen phosphate solution; when mixing the coating, first stir manually with a spatula until there is no sediment, then use a homogenizer to further mix the microwave absorbing coating until the coating is uniformly mixed. The process parameters for the homogenizer when mixing the coating are set as follows: rotation speed is set to 1500 r / min, and mixing time is set to 3 min;

[0081] 4) Preparation of coating material: The radar absorbing layer coating obtained in step 3) is uniformly sprayed onto the radar bonding layer prepared in step 2) using air spraying technology and cured to form a high-temperature resistant radar absorbing coating material;

[0082] In the preparation of the coating material, air spraying and curing are repeated alternately until the thickness of the high-temperature resistant radar-absorbing coating material reaches 1.2 mm (flush with the original coating material). Then, the flat titanium alloy substrate coated with the high-temperature resistant radar-absorbing coating material is heat-treated. The specific operation is as follows:

[0083] During air spraying, the weight gain per spray is 20g. During curing, a high-temperature oven with a temperature difference of ≤15℃ is used. The curing process is as follows: first, cure at room temperature for 30 minutes until surface dry, then use the curing equipment to raise the temperature from room temperature to 85℃ and hold for 8 minutes, then raise the temperature to 160℃ and hold for 8 minutes, then raise the temperature to 310℃ and hold for 4 minutes, and finally cool down to 55℃ with the curing equipment, then remove the flat titanium alloy substrate and allow it to cool naturally to room temperature. The heat treatment process is as follows: the cured flat titanium alloy substrate is heated from room temperature to 360℃ and held for 25 minutes.

[0084] Finally, reflection loss tests were conducted on multiple batches of the prepared high-temperature resistant radar absorbing coating materials. The testing equipment was a vector network analyzer, and the testing method was the bow-shaped method. The test results are as follows: Figure 2 As shown:

[0085] pass Figure 2Analysis of the test results shows that the three batches of high-temperature radar absorbing coating materials (ceramic-alloy system) prepared in Example 1 of this invention all have excellent high-temperature absorption performance. After comparison with the original ceramic high-temperature radar absorbing coating materials, their appearance is similar and their reflectivity curves at high temperatures are consistent.

[0086] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention.

[0087] It should be understood that the present invention is not limited to the content already described above, and various modifications and changes can be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A high-temperature resistant radar-absorbing coating material for repair, characterized in that, It includes a radar bonding layer and a radar absorbing layer. The radar bonding layer is sprayed onto the metal substrate to be repaired after sandblasting. The radar absorbing layer coating is uniformly sprayed onto the radar bonding layer by air spraying and cured to form a high-temperature resistant radar absorbing coating material. The radar absorbing layer coating includes Al2O3 powder and FeCr. 21 Al4 powder, CaTi 0.05 Mn 0.95 O3 powder and inorganic salt binder, and the Al2O3 powder and FeCr 21 Al4 powder, CaTi 0.05 Mn 0.95 The mass ratio of O3 powder to inorganic salt binder is 1:1:1:(2.5~3.5); the radar bonding layer mainly includes Ni, Co, Cr, Al and Y elements; The Al2O3 powder is composed of Al2O3 powder with a particle size ≤5μm and Al2O3 powder with a particle size of 15μm~75μm mixed in a mass ratio of 1~9∶9~1; The FeCr 21 The composition and ratio of Al4 powder are: 20.0wt%~22.0wt% Cr, 3.0wt%~5.0wt% Al and 73wt%~77wt% Fe; The inorganic salt binder is an aluminum dihydrogen phosphate solution with a solid content of 20wt% to 30wt%. The air spraying and curing processes are repeated alternately until the thickness of the high-temperature resistant radar absorbing coating material is 1.0 mm to 1.2 mm. Then, the metal substrate coated with the high-temperature resistant radar absorbing coating material is heat-treated. The curing process is carried out using a resistance furnace or high-temperature oven with a temperature difference of ≤15℃. The curing process is as follows: first, cure at room temperature for ≥10 minutes until the surface is dry; then, use the curing equipment to raise the temperature from room temperature to 75℃~85℃ and hold for 8 minutes~12 minutes; then raise the temperature to 140℃~160℃ and hold for 8 minutes~12 minutes; then raise the temperature to 290℃~310℃ and hold for 4 minutes~6 minutes; finally, cool down to ≤100℃ with the curing equipment, remove the metal substrate and allow it to cool naturally to room temperature. The heat treatment process is as follows: the cured metal substrate is heated from room temperature to 340℃~360℃ and held for 25min~35min.

2. The high-temperature resistant radar-absorbing coating material for repair according to claim 1, characterized in that, The thickness of the radar bonding layer is 100±15μm; the thickness of the high-temperature resistant radar absorbing coating material is 1.0mm~1.2mm.

3. The method for preparing the high-temperature resistant radar absorbing coating material for repair according to claim 1 or 2, characterized in that, Specifically, the following steps are included: Step 1: Substrate pretreatment: Sandblast the metal substrate to be repaired to remove oxides and impurities from its surface. Step 2: Prepare the radar bonding layer: Spray the radar bonding layer onto the sandblasted metal substrate to be repaired. Step 3: Preparation of radar absorbing layer coating: Weigh Al2O3 powder and FeCr according to a mass ratio of 1:1:1:(2.5~3.5). 21 Al4 powder, CaTi 0.05 Mn 0.95 O3 powder and inorganic salt binder are mixed evenly to obtain radar absorbing layer coating; Step 4: Prepare coating material: Use air spraying technology to uniformly spray the radar absorbing layer coating obtained in step 3 onto the radar bonding layer prepared in step 2, and then cure it to form a high-temperature resistant radar absorbing coating material.

4. The preparation method according to claim 3, characterized in that, In step two, the surface roughness of the metal substrate to be repaired after sandblasting is 5μm to 15μm, and the flatness of the surface of the metal substrate to be repaired after sandblasting is ≤1.0mm.

5. The preparation method according to claim 3, characterized in that, In step three, the Al2O3 powder and FeCr 21 Al4 powder, CaTi 0.05 Mn 0.95 When mixing O3 powder and inorganic salt binder, first use a spatula to manually stir until there is no sediment, and then use a homogenizer to further mix the microwave absorbing coating until the microwave absorbing coating is evenly mixed. The process parameters for the homogenizing disperser when mixing the microwave absorbing coating are set as follows: rotation speed is set to 1000 r / min to 1500 r / min, and mixing time is set to 3 min to 5 min.

6. The preparation method according to claim 3, characterized in that, During air spraying, the weight gain per spray is 10g to 20g.

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