Ceramic-based high-temperature wave-absorbing coating, preparation method and application

Abstract

The invention belongs to the technical field of preparation of stealth coatings, and particularly discloses a ceramic-based high-temperature wave-absorbing coating as well as a preparation method and application thereof. The porosity of the coating is regulated and controlled by introducing the pore-forming agent into the preparation raw materials of the ceramic-based high-temperature wave-absorbing coating, so that the coating has the following advantages: 1) the electromagnetic property of the ceramic loss layer can be effectively regulated and controlled, impedance matching is optimized, and good stealth performance at 550 DEG C is ensured; 2) the material has good thermal shock resistance and high-temperature stability, and can work at 550 DEG C for a long time; and (3) raw materials of the coating are convenient to obtain, the preparation process is simple, and the coating has the advantage of low surface density, can be produced in batches, is low in cost and meets the performance requirements of the high-temperature-resistant stealth coating. The preparation process and parameters of the coating are fully optimized, the preparation process is effectively simplified, meanwhile, the performance indexes of the ceramic-based stealth coating are comprehensively improved, and the ceramic-based stealth coating has good application prospects in the field of high-temperature stealth.

Description

Technical Field

[0001] The present invention belongs to the technical field of stealth coating preparation, and specifically relates to a ceramic-based high-temperature radar absorbing coating, and a preparation method and application of the high-temperature radar absorbing coating. Background Art

[0002] In order to cope with the increasingly complex electromagnetic environment of the modern battlefield, improve the survivability and strike capability of weapons and equipment, and meet the needs of future air confrontations, the new generation of fighters have put forward higher requirements on the stealth performance of the entire aircraft, especially the high-temperature parts. This also makes the research and development of comprehensive high-temperature resistant stealth coatings a hot spot and difficulty in current research.

[0003] In order to develop a qualified high-temperature stealth coating product, a comprehensive performance assessment is required. In addition to the basic high-temperature stealth performance, the coating material also needs to have high-temperature stability, thermal shock resistance, low surface density and low thickness, which also puts higher requirements on the selection of coating materials and the preparation process of the coating. The existing process usually uses plasma spraying technology to prepare ceramic-based high-temperature stealth coatings, but it is limited by the shortcomings of poor impedance matching of the ceramic loss layer and difficult to control electromagnetic properties. Most of them face the problems of complex process, high cost and difficulty in further optimizing performance.

[0004] Studies have shown that the electromagnetic loss and impedance matching of ceramic-based absorbing coatings are poor. It is difficult to effectively control the absorption loss curve of the coating only by adjusting the content of the absorber. If the absorber content is too high, the matching performance is poor, and if the content is too low, the loss characteristics are difficult to play. In order to obtain better absorbing performance and to make the coating obtain good thermal stability and thermal shock resistance, the selection of coating materials and the thermal matching of the coating should be considered as a whole, which also increases the design difficulty and the preparation process is relatively complicated. For example, Chinese patent application CN118599346A (Chinese People's Liberation Army Rocket Force Engineering University) discloses a heat-proof and stealth dual-function coating material that can be coated and formed, which is made by mixing SiC-based composite ceramic aerogel slurry and perovskite / MAX phase composite ceramic absorber in proportion and then coating, wherein the porous structure of the composite ceramic aerogel is conducive to the entry of electromagnetic waves into the composite material, increasing the impedance matching between the material and the electromagnetic wave, thereby improving the coating's absorption of electromagnetic waves, and the porous structure also gives the coating a better thermal insulation effect. However, the preparation process of the coating material is complicated, especially SiC nanoparticles are difficult to disperse, and there are many types of raw materials and high preparation costs.

[0005] Therefore, there is an urgent need to develop a ceramic-based high-temperature radar absorbing coating with easily available raw materials, simple preparation process and low cost. Summary of the invention

[0006] The main technical problem solved by the present invention is to provide a ceramic-based high-temperature absorbing coating. By introducing a pore-forming agent into the raw material to regulate the porosity of the ceramic coating, the impedance matching characteristics of the ceramic layer are effectively optimized. At the same time, the thermal shock resistance and thermal stability of the coating are greatly improved, and the surface density of the coating is reduced.

[0007] At the same time, the present invention provides a method for preparing a ceramic-based high-temperature absorbing coating based on porosity adjustment to optimize coating performance, fully optimizes the coating preparation process and parameters, has a simple preparation process and low cost, achieves a comprehensive improvement in the performance indicators of the ceramic-based stealth coating, and has good application prospects in the field of high-temperature stealth.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0009] A ceramic-based high-temperature microwave absorbing coating, the raw materials for preparation thereof include, by weight percentage:

[0010] Conductive ceramic component 1: 30% to 50%;

[0011] Conductive ceramic component 2: 4% to 20%;

[0012] High temperature wave-transmitting agent: 30% to 50%;

[0013] Pore-forming agent: 2%~20%.

[0014] As a preferred embodiment of the present invention, the conductive ceramic component 1 is selected from one or more of strontium lanthanum manganate, strontium lanthanum ferrite, and strontium lanthanum cobaltate, and more preferably strontium lanthanum cobaltate (LaSrCoO3).

[0015] As a preferred embodiment of the present invention, the conductive ceramic component 2 is selected from one or more of MoSi2 (silicon-based), TiC (carbon-based), TiN (nitrogen-based), etc. All of the above materials have good high-temperature conductivity.

[0016] As a preferred embodiment of the present invention, the high temperature wave-transmitting agent is selected from one or more of Al2O3, ZrO2, SiO2 and the like.

[0017] As a preferred embodiment of the present invention, the pore-forming agent is selected from one or both of urea and polyphenyl ester, and more preferably polyphenyl ester.

[0018] Specifically, the polyphenylene ester is a commercially available product, and a spherical powder with a particle size of 10 to 30 μm can be selected.

[0019] As a preferred embodiment of the present invention, the conductive ceramic component 1 is strontium lanthanum cobaltate, the conductive ceramic component 2 is MoSi2, the high-temperature wave-transmitting agent is Al2O3, and the pore-forming agent is polyphenylene ester.

[0020] As a preferred embodiment of the present invention, the raw materials for preparing the ceramic-based high-temperature absorbing coating include, by weight percentage:

[0021] LaSrCoO3: 38%~42%;

[0022] MoSi2: 9%~14%;

[0023] Al2O3: 38%~42%;

[0024] Polyphenylene ester: 6%~10%.

[0025] A method for preparing a ceramic-based high-temperature microwave absorbing coating comprises the following steps:

[0026] S1: mixing the conductive ceramic component 1 and the high-temperature wave-transmitting agent and spraying and granulating them to obtain granulated powder;

[0027] S2: fully mixing the granulated powder, the conductive ceramic component 2 and the pore-forming agent to obtain the powder to be sprayed;

[0028] S3: spraying the powder to be sprayed, and then heat treating to obtain a ceramic-based high-temperature radar absorbing coating.

[0029] As a preferred embodiment of the present invention, in step S1, the spray granulation is: mixing a mixed dry powder of the conductive ceramic component 1 and the high-temperature wave-transmitting agent with water in a mass ratio of 1:5-8, adding a binder accounting for 3wt%-8wt% of the mixture, and setting the following parameters for spray granulation: the air supply temperature is 200-250°C, the air outlet temperature is 100-150°C, and the atomizer frequency is 150-200Hz.

[0030] Specifically, the binder is a polyvinyl alcohol (PVA) aqueous solution with a concentration of 5wt% to 30wt%.

[0031] Specifically, a small amount of thickener (such as methylcellulose M450) or dispersant (such as hand soap) can be added depending on the slurry conditions.

[0032] As a preferred embodiment of the present invention, in step S3, the spraying adopts a plasma spraying process, and the process parameters are as follows: Ar flow rate is 20-60L / min, H2 flow rate is 3-10L / min, spraying power is 30-60kW, spraying distance is 70-130mm, spray gun moving speed is 300-600mm / s, and powder feeding amount is 10-50g / min.

[0033] As a preferred embodiment of the present invention, in step S3, the technical parameters of the heat treatment are as follows: the heating rate is 5-15°C / min, the temperature is raised to 300-600°C, and the temperature is kept for 4-10 hours before cooling with the furnace.

[0034] The invention discloses an application of a ceramic-based high-temperature radar-absorbing coating in the preparation of a stealth coating.

[0035] As a preferred embodiment of the present invention, the application comprises the following steps:

[0036] (1) Spraying on the surface of the metal lining to obtain a metal bonding layer;

[0037] (2) A ceramic-based high-temperature radar absorbing coating is prepared on the surface of the metal bonding layer, thereby obtaining a stealth coating.

[0038] As a preferred embodiment of the present invention, in step (1), the raw materials for preparing the metal bonding layer are selected from one or two of NiCrAlY and NiCrAl.

[0039] As a preferred embodiment of the present invention, in step (1), the spraying adopts a plasma spraying process, and the process parameters are as follows: Ar flow rate is 20-60 L / min, H2 flow rate is 3-6 L / min, spraying power is 20-50 kW, spraying distance is 70-130 mm, spray gun moving speed is 200-500 mm / s, and powder feeding amount is 10-50 g / min.

[0040] As a preferred embodiment of the present invention, in step (1), the thickness of the metal bonding layer is 0.05 to 0.15 mm.

[0041] As a preferred embodiment of the present invention, in step (2), the raw materials and preparation method of the ceramic-based high-temperature absorbing coating are the same as above.

[0042] As a preferred embodiment of the present invention, in step (2), the thickness of the ceramic-based high-temperature absorbing coating is 1.0 to 1.5 mm.

[0043] Beneficial effects of the present invention:

[0044] The present invention provides a ceramic-based high-temperature absorbing coating with optimized coating performance based on porosity regulation, and the coating has the following advantages: 1) it can effectively regulate the electromagnetic properties of the ceramic loss layer, optimize impedance matching, and ensure good stealth performance at 550°C; 2) it has good thermal shock resistance and high-temperature stability, and can work for a long time at 550°C; 3) the coating raw materials are easy to obtain, the preparation process is simple, it has the advantage of low surface density, can be mass-produced, and has low cost, meeting the performance requirements of high-temperature resistant stealth coatings.

[0045] The present invention introduces a pore-forming agent into the raw materials for preparing the ceramic-based high-temperature absorbing coating to regulate the porosity of the coating, thereby achieving effective optimization of the impedance matching characteristics of the ceramic layer, while effectively improving the thermal shock resistance and thermal stability of the coating and reducing the surface density of the coating.

[0046] The method for preparing a ceramic-based high-temperature absorbing coating based on porosity adjustment to optimize coating performance provided by the present invention effectively simplifies the preparation process by fully optimizing the preparation process and parameters of the coating, while achieving a comprehensive improvement in the performance indicators of the ceramic-based stealth coating, and has good application prospects in the field of high-temperature stealth. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 Schematic diagram of the structure of the stealth coating.

[0048] Figure 2 This is a process flow chart for preparing ceramic-based high-temperature absorbing coatings.

[0049] Figure 3 Reflection loss of coatings at 550°C before and after adjustment for porosity.

[0050] Figure 4 Metallographic pictures of the thermal shock specimen and the specimen cross section;

[0051] In the figure, (a) the actual thermal shock sample; (b) the metallographic structure and porosity calibration of the left sample (containing 8% polyphenyl ester pore-forming agent); (c) the metallographic structure and porosity calibration of the right sample (without pore-forming agent).

[0052] In order to more clearly illustrate the technical solution to be protected by the present invention, the drawings in the embodiments and / or experimental examples are briefly introduced above. It should be understood that the above drawings should not be regarded as any limitation on the protection scope of the present invention. DETAILED DESCRIPTION

[0053] The technical solution of the present invention is described in detail below through specific embodiments. The following embodiments are intended to further illustrate the content of the present invention in detail, but are not intended to limit the scope of protection of the claims of the present invention.

[0054] In the following examples and comparative examples, unless otherwise specified, the raw materials, reagents, equipment, etc. used are all commercially available products. The lanthanum strontium cobaltate (LaSrCoO3) used was purchased from the Institute of Process Engineering, Chinese Academy of Sciences, and the product was a spherical powder with a particle size of 8 μm; the polyphenylene ester used was purchased from Wuhan University of Technology, and the product was a spherical powder with a particle size of 20 μm.

[0055] Example 1

[0056] This embodiment provides a ceramic-based high-temperature radar absorbing coating. The raw materials for its preparation include, by weight percentage:

[0057] LaSrCoO3: 40.25%;

[0058] MoSi2: 11.5%;

[0059] Al2O3: 40.25%;

[0060] Polyphenylene ester: 8%.

[0061] This embodiment also provides a method for preparing a ceramic-based high-temperature microwave absorbing coating, comprising the following steps:

[0062] S1: LaSrCoO3 and Al2O3 are mixed and spray granulated to obtain granulated powder;

[0063] The specific operation of the spray granulation is as follows: a mixed dry powder of LaSrCoO3 and Al2O3 is mixed with water in a mass ratio of 1:6, a PVA aqueous solution (concentration of 10wt%) accounting for 5wt% of the mixture is added, and the following parameters are set for spray granulation: the air supply temperature is 220°C, the air outlet temperature is 120°C, and the atomizer frequency is 150Hz;

[0064] S2: Fully mechanically mixing the granulated powder, MoSi2 and polyphenylene ester to obtain powder to be sprayed;

[0065] S3: The powder to be sprayed is sprayed by plasma spraying process, and the process parameters are as follows: Ar flow rate is 40L / min, H2 flow rate is 4L / min, spraying power is 32kW, spraying distance is 80mm, spray gun moving speed is 500mm / s, and powder feeding amount is 20g / min; heat treatment is carried out after spraying, and the technical parameters are as follows: heating rate is 10℃ / min, heating to 500℃, keeping warm for 8h and then cooling with the furnace to obtain a ceramic-based high-temperature radar absorbing coating.

[0066] This embodiment also provides a ceramic-based high-temperature absorbing coating for preparing a stealth coating (schematic diagram of the structure as shown in FIG. Figure 1 The application of (as shown) comprises the following steps:

[0067] (1) A metal bonding layer with a thickness of 0.1 mm was prepared on the surface of a metal liner (TA15 titanium alloy) by plasma spraying. The raw material was NiCrAlY. The plasma spraying process parameters were as follows: Ar flow rate was 40 L / min, H2 flow rate was 6 L / min, spraying power was 35 kW, spraying distance was 130 mm, spray gun moving speed was 500 mm / s, and powder feeding amount was 20 g / min;

[0068] (2) A ceramic-based high-temperature absorbing coating with a thickness of 1.2 mm was prepared on the surface of the metal bonding layer. LaSrCoO3 and Al2O3 were first mixed and then spray granulated (the operation was the same as above) to obtain granulated powder;

[0069] The granulated powder, MoSi2 and the pore-forming agent are fully mechanically mixed to obtain the powder to be sprayed;

[0070] The powder to be sprayed is sprayed using a plasma spraying process. The process parameters are as follows: Ar flow rate is 40L / min, H2 flow rate is 4L / min, spraying power is 32kW, spraying distance is 80mm, spray gun moving speed is 500mm / s, and powder feeding amount is 20g / min; heat treatment is carried out after spraying, and the technical parameters are as follows: heating rate is 10℃ / min, heating to 500℃, keeping warm for 8h and then cooling with the furnace to obtain a (high temperature resistant) stealth coating.

[0071] Example 2

[0072] This embodiment provides a ceramic-based high-temperature radar absorbing coating. The raw materials for its preparation include, by weight percentage:

[0073] LaSrCoO3: 45%;

[0074] MoSi2: 6%;

[0075] Al2O3: 45%;

[0076] Polyphenylene ester: 4%.

[0077] This embodiment also provides an application of a ceramic-based high-temperature radar absorbing coating in preparing a stealth coating, comprising the following steps:

[0078] (1) A metal bonding layer with a thickness of 0.1 mm was prepared on the surface of the metal liner by plasma spraying process. The raw material was NiCrAlY. The plasma spraying process parameters were as follows: Ar flow rate was 30 L / min, H2 flow rate was 4 L / min, spraying power was 30 kW, spraying distance was 100 mm, spray gun moving speed was 400 mm / s, and powder feeding amount was 30 g / min;

[0079] (2) A ceramic-based high-temperature absorbing coating with a thickness of 1.2 mm was prepared on the surface of the metal bonding layer. LaSrCoO3 and Al2O3 were first mixed and then spray granulated (the operation was the same as in Example 1) to obtain granulated powder;

[0080] The granulated powder, MoSi2 and polyphenylene ester are fully mechanically mixed to obtain the powder to be sprayed;

[0081] The powder to be sprayed is sprayed using a plasma spraying process. The process parameters are as follows: Ar flow rate is 30L / min, H2 flow rate is 3L / min, spraying power is 40kW, spraying distance is 90mm, spray gun moving speed is 400mm / s, and powder feeding amount is 30g / min; after spraying, heat treatment is carried out, and the technical parameters are as follows: heating rate is 5℃ / min, heating to 400℃, keeping warm for 10h and then cooling with the furnace to obtain a (high temperature resistant) stealth coating.

[0082] Example 3

[0083] This embodiment provides a ceramic-based high-temperature radar absorbing coating. The raw materials for its preparation include, by weight percentage:

[0084] LaSrCoO3: 36%;

[0085] MoSi2: 16%;

[0086] Al2O3: 36%;

[0087] Polyphenylene ester: 12%.

[0088] This embodiment also provides an application of a ceramic-based high-temperature radar absorbing coating in preparing a stealth coating, comprising the following steps:

[0089] (1) A metal bonding layer with a thickness of 0.1 mm was prepared on the surface of the metal liner by plasma spraying process. The raw material was NiCrAlY. The plasma spraying process parameters were as follows: Ar flow rate was 50 L / min, H2 flow rate was 3 L / min, spraying power was 40 kW, spraying distance was 70 mm, spray gun moving speed was 500 mm / s, and powder feeding amount was 50 g / min;

[0090] (2) A ceramic-based high-temperature absorbing coating with a thickness of 1.2 mm was prepared on the surface of the metal bonding layer. LaSrCoO3 and Al2O3 were first mixed and then spray granulated (the operation was the same as in Example 1) to obtain granulated powder;

[0091] The granulated powder, MoSi2 and polyphenylene ester are fully mechanically mixed to obtain the powder to be sprayed;

[0092] The powder to be sprayed is sprayed using a plasma spraying process. The process parameters are as follows: Ar flow rate is 60L / min, H2 flow rate is 8L / min, spraying power is 50kW, spraying distance is 100mm, spray gun moving speed is 500mm / s, and powder feeding amount is 50g / min; heat treatment is carried out after spraying, and the technical parameters are as follows: heating rate is 10℃ / min, heating to 600℃, keeping warm for 4h and then cooling with the furnace to obtain a (high temperature resistant) stealth coating.

[0093] The reflection loss curve of the absorbing coating is affected by the content of the conductive ceramic and the porosity of the coating (the proportion of the pore-forming agent). The amount of each component depends on the performance requirements of the coating. In other embodiments of the present invention, the raw materials for preparing the ceramic-based high-temperature absorbing coating and the metal bonding layer can be selected or taken within the given type and amount range.

[0094] In other embodiments of the present invention, the technical parameters of spray granulation, plasma spraying, heat treatment, etc. can be taken within a given range.

[0095] In other embodiments of the present invention, the thickness of the metal bonding layer and the thickness of the ceramic-based high-temperature absorbing coating can be within a given range.

[0096] Experimental example

[0097] This experiment uses the Figure 2 The process flow shown is used to prepare waveguide samples and thermal shock samples. The metal liner material used is TA15 titanium alloy. The size of the high-temperature absorbing coating sample is 180mm×180mm×3mm, and the size of the thermal shock sample is 40mm×20mm×3mm. The experimental method includes: (1) fully mechanically mixing ceramic loss layer powders with different ratios and pore-forming agent powders with different ratios to obtain powders to be sprayed; (2) using plasma spraying technology to prepare waveguide samples and thermal shock samples with different ratios of powders to be sprayed; (3) placing the sample in a muffle furnace for heat treatment for a period of time to remove the pore-forming agent, measuring the high-temperature electromagnetic parameters of the waveguide sample after heat treatment and calculating the reflection loss, characterizing the number of water-cooled thermal shock cycles of the thermal shock sample, and determining the component ratio of the sample with satisfactory thermal shock performance and excellent target frequency domain performance; (4) using plasma spraying technology to prepare a ceramic loss layer with a determined component ratio, and placing the ceramic loss layer in a muffle furnace for heat treatment for a period of time to remove the pore-forming agent to obtain a finished ceramic-based high-temperature absorbing coating.

[0098] Specifically, the experimental method includes the following steps:

[0099] (1) Obtaining powders to be sprayed with different proportions: LaSrCoO3 and Al2O3 are sprayed and granulated according to a certain mass ratio (the operation is the same as above), wherein the mass proportion of LaSrCoO3 is 40% to 70%, and then the obtained granulated powder is fully mechanically mixed with a certain proportion of MoSi2 and a pore-forming agent to obtain the powder to be sprayed, wherein the mass proportion of MoSi2 is 4% to 20%, and the pore-forming agent is urea and / or polyvinyl ester, and the mixing ratio is 2% to 20%.

[0100] (2) The waveguide specimen and thermal shock specimen to be sprayed with powder were prepared by plasma spraying process: the composition of the metal bonding layer on the surface of the metal liner was NiCrAlY, and the plasma spraying process parameters were: Ar flow rate was 20-60 L / min, H2 flow rate was 3-6 L / min, spraying power was 20-50 kW, spraying distance was 70-130 mm, spray gun moving speed was 200-500 mm / s, and powder feeding amount was 10-50 g / min; the plasma spraying process parameters of the ceramic loss layer (i.e., ceramic-based high-temperature absorbing coating) were: Ar flow rate was 20-60 L / min, H2 flow rate was 3-10 L / min, spraying power was 30-60 kW, spraying distance was 70-130 mm, spray gun moving speed was 300-600 mm / s, and powder feeding amount was 10-50 g / min.

[0101] (3) Heat treatment of samples and characterization of high-temperature electromagnetic parameters and thermal shock performance: The waveguide sample and the thermal shock sample are placed in a muffle furnace with a heating rate of 5 to 15 °C / min to 300 to 600 °C. The temperature is kept at this temperature for 4 to 10 h and then cooled in the furnace. The high-temperature electromagnetic parameters of the sample at 550 °C and the number of water-cooled thermal shock cycles are characterized to determine the component ratio.

[0102] (4) A plasma spraying process is used to prepare a ceramic-based high-temperature absorbing coating with a determined component ratio: the metal liner is chamfered, degreased and sandblasted; a metal bonding layer is sprayed on the surface of the metal liner by a plasma spraying process, and the spraying process parameters are as in step (2); a ceramic-based high-temperature absorbing coating with a determined component ratio is sprayed on the surface of the metal bonding layer by a plasma spraying process, and the spraying process parameters are as in step (2); the ceramic loss layer is heat treated, and the process is as in step (3).

[0103] In view of the Ku-band absorption performance requirements, the raw material ratios finally determined in this experimental example are shown in Table 1 below.

[0104] Table 1 Raw materials for preparing ceramic-based high-temperature absorbing coatings (by mass percentage)

[0105]

[0106] The final preparation process parameters determined in this experimental example are as follows:

[0107] (1) The thickness of the metal bonding layer is 0.1 mm. The plasma spraying process parameters are: Ar flow rate is 40 L / min, H2 flow rate is 6 L / min, spraying power is 35 kW, spraying distance is 130 mm, spray gun moving speed is 500 mm / s, and powder feeding amount is 20 g / min.

[0108] (2) The thickness of the ceramic-based high-temperature absorbing coating is 1.2 mm. The plasma spraying process parameters are: Ar flow rate is 40 L / min, H2 flow rate is 4 L / min, spraying power is 32 kW, spraying distance is 80 mm, spray gun moving speed is 400 mm / s, and powder feeding amount is 20 g / min.

[0109] (3) The pore-forming agent polyphenyl ester was removed by heat treatment. The program parameters of the muffle furnace were as follows: the heating rate was 10°C / min, the temperature was raised to 500°C, and the temperature was kept at this temperature for 8 hours before cooling with the furnace.

[0110] The characterization results of this experimental example are as follows:

[0111] Figure 3 In order to keep the absorption peak position similar, the reflection loss of the coating at 550°C is compared before and after porosity adjustment.

[0112] Figure 4 Metallographic pictures of the thermal shock specimen and the specimen cross section;

[0113] Among them, the porosity of the left sample (80.5% LaSrCoO3 / Al2O3-11.5% MoSi2-8% polyphenylene ester) is 55%; after 10 cycles of 550℃ water cooling thermal shock, the coating did not fall off;

[0114] The porosity of the right sample (90% LaSrCoO3 / Al2O3+10% MoSi2) is 42%, and the coating falls off completely after three 550℃ water-cooling thermal shock cycles.

[0115] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention specification, or directly or indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A ceramic-based high-temperature microwave absorbing coating, characterized in that: Calculated by mass percentage, the preparation raw materials include: Conductive ceramic component 1: 30% to 50%; Conductive ceramic component 2: 4% to 20%; High temperature wave-transmitting agent: 30% to 50%; Pore-forming agent: 2%~20%.

2. The ceramic-based high-temperature microwave absorbing coating according to claim 1, characterized in that: The conductive ceramic component 1 is selected from one or more of strontium lanthanum manganate, strontium lanthanum ferrite, and strontium lanthanum cobaltate; And / or, the conductive ceramic component 2 is selected from one or more of MoSi2, TiC, and TiN; And / or, the high temperature wave-transmitting agent is selected from one or more of Al2O3, ZrO2, and SiO2; And / or, the pore-forming agent is selected from one or both of urea and polyphenylene ester.

3. The ceramic-based high-temperature microwave absorbing coating according to claim 1, characterized in that: The conductive ceramic component 1 is strontium lanthanum cobaltate, the conductive ceramic component 2 is MoSi2, the high-temperature wave-transmitting agent is Al2O3, and the pore-forming agent is polyphenylene ester.

4. A method for preparing a ceramic-based high-temperature microwave absorbing coating according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1: mixing the conductive ceramic component 1 and the high-temperature wave-transmitting agent and spraying and granulating them to obtain granulated powder; S2: fully mixing the granulated powder, the conductive ceramic component 2 and the pore-forming agent to obtain the powder to be sprayed; S3: spraying the powder to be sprayed, and then heat treating to obtain a ceramic-based high-temperature radar absorbing coating.

5. The preparation method according to claim 4, characterized in that: In step S1, the spray granulation is: mixing the mixed dry powder of the conductive ceramic component 1 and the high-temperature wave-transmitting agent with water in a mass ratio of 1:5-8, adding a binder accounting for 3wt%-8wt% of the mixture, and setting the following parameters for spray granulation: the air supply temperature is 200-250°C, the air outlet temperature is 100-150°C, and the atomizer frequency is 150-200Hz.

6. The preparation method according to claim 4, characterized in that: In step S3, the spraying adopts a plasma spraying process, and the process parameters are as follows: Ar flow rate is 20-60 L / min, H2 flow rate is 3-10 L / min, spraying power is 30-60 kW, spraying distance is 70-130 mm, spray gun moving speed is 300-600 mm / s, and powder feeding amount is 10-50 g / min; And / or, in step S3, the technical parameters of the heat treatment are as follows: a heating rate of 5 to 15°C / min, heating to 300 to 600°C, keeping warm for 4 to 10 hours and then cooling with the furnace.

7. Use of the ceramic-based high-temperature radar absorbing coating according to any one of claims 1 to 3 in the preparation of a stealth coating.

8. The use according to claim 7, characterized in that: The application comprises the following steps: (1) Spraying on the surface of the metal lining to obtain a metal bonding layer; (2) A ceramic-based high-temperature radar absorbing coating is prepared on the surface of the metal bonding layer, thereby obtaining a stealth coating.

9. The use according to claim 8, characterized in that: In step (1), the raw materials for preparing the metal bonding layer are selected from one or two of NiCrAlY and NiCrAl; And / or, in step (1), the spraying adopts a plasma spraying process, and the process parameters are as follows: Ar flow rate is 20-60 L / min, H2 flow rate is 3-6 L / min, spraying power is 20-50 kW, spraying distance is 70-130 mm, spray gun moving speed is 200-500 mm / s, and powder feeding amount is 10-50 g / min.

10. The use according to claim 8, characterized in that: In step (1), the thickness of the metal bonding layer is 0.05 to 0.15 mm; And / or, in step (2), the thickness of the ceramic-based high-temperature absorbing coating is 1.0 to 1.5 mm.

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