High-temperature-resistant wave-absorbing coating with environmental barrier characteristic and structural member

Abstract

The invention relates to the technical field of electromagnetic wave absorbing materials, and provides a high-temperature-resistant wave-absorbing coating with environmental barrier characteristics and a structural member, the high-temperature-resistant wave-absorbing coating is composed of doped and modified high-temperature-resistant wave-absorbing ceramic, and the conductivity of the doped and modified high-temperature-resistant wave-absorbing ceramic is greater than or equal to 10 <-4 > S / cm and less than or equal to 10 <-1 > S / cm. The high-temperature-resistant wave-absorbing coating can serve as an environment barrier layer to provide protection for a silicon-based ceramic composite material matrix layer and can have good mechanical performance and wave-absorbing performance in a high-temperature environment, the stealth performance of target equipment in the high-temperature environment is improved, and the service life of the target equipment in the high-temperature environment is prolonged.

Description

Technical Field

[0001] The present application relates to the technical field of electromagnetic wave absorbing materials, and in particular to a high temperature resistant absorbing coating with environmental barrier properties, and a structural member formed by using the high temperature resistant absorbing coating with environmental barrier properties. Background Art

[0002] As stealth equipment becomes more and more important in modern combat, the performance improvement of radar-absorbing coatings has also become a research and development focus. The radar-absorbing coating is applied on the substrate layer, not directly on the surface of the structural parts. With the emergence of silicon-based ceramic composites, such as SiC, Si3N4, C / SiC and SiC / SiC ceramic composites, they are often used to replace nickel-based alloys as the substrate material for carrying radar-absorbing coatings because of their good mechanical strength and creep resistance in dry environments above 1000°C, as well as their low density and excellent thermal shock resistance.

[0003] However, when the absorbing coating is scratched or damaged by external factors, the silicon-based ceramic composite matrix will be exposed. When the silicon-based ceramic composite matrix is ​​exposed to a high-temperature, high-velocity water vapor environment or an environment with aviation fuel additives, sand and gravel containing CaO-MgO-Al2O3-SiO2 (CMAS), or volcanic ash, it will be severely corroded and the stability will decrease rapidly, leading to the failure of the absorbing coating. In addition, after the absorbing coating is scratched or damaged by external factors, the absorbing performance and mechanical properties will be greatly reduced, or even completely fail.

[0004] Therefore, it is of great significance to develop a high-temperature resistant and microwave-absorbing coating that has both environmental barrier properties and microwave-absorbing performance. Summary of the invention

[0005] The purpose of the present application is to provide a high-temperature resistant absorbing coating with environmental barrier properties and a structural member formed by using the high-temperature resistant absorbing coating with environmental barrier properties, so as to solve the problem in the prior art that the traditional absorbing coating cannot provide effective environmental protection for the silicon-based ceramic composite material substrate layer after being mechanically damaged, so that the stability of the silicon-based ceramic composite material substrate layer is reduced, and then the absorbing coating is easy to peel off, and at the same time, the mechanical properties and absorbing properties of the absorbing coating are reduced after being mechanically damaged.

[0006] Other features and advantages of the present application will become apparent from the following detailed description, or may be learned in part by the practice of the present application.

[0007] According to a first aspect of the present application, a high temperature resistant absorbing coating having environmental barrier properties is provided: the high temperature resistant absorbing coating is composed of a doped and modified high temperature resistant absorbing ceramic, wherein the electrical conductivity of the doped and modified high temperature resistant absorbing ceramic is greater than or equal to 10-4 S / cm and less than or equal to 10 -1 S / cm.

[0008] In some embodiments of the present application, the doped and modified high temperature resistant absorbing ceramic is one or more of: doped and modified rare earth monosilicate, doped and modified rare earth pyrosilicate, doped and modified rare earth phosphate, and doped and modified rare earth tantalate.

[0009] In some embodiments of the present application, the molecular formula of the doped rare earth monosilicate is ReSi 1-X B X O5, the molecular formula of the doped modified rare earth pyrosilicate is Re2Si 2-Y B Y O7, the molecular formula of the doped modified rare earth phosphate is ReP 1-X B X O4, the molecular formula of the doped and modified rare earth tantalate is ReTa 1-X B x O4;

[0010] Among them, Re is La, Ce, Pr, Sc, Nd, Sm, Eu, Tb, Yb, Y, Ho, Dy, Lu, Tm, Er or Gd; B is Fe, Ti, B, Co, Mn, P, Ga or Ge; X is greater than 0 and less than or equal to 0.5; Y is greater than 0 and less than or equal to 1.

[0011] In some embodiments of the present application, the particle size of the doped and modified high temperature resistant absorbing ceramic is less than or equal to 90 μm, and the thickness of the high temperature resistant absorbing coating is greater than or equal to 1 mm and less than or equal to 2 mm.

[0012] In some embodiments of the present application, the high temperature resistant absorbing coating is composed of the doped modified high temperature resistant absorbing ceramic and the absorbing agent, so that the high temperature resistant absorbing coating has both environmental barrier properties and self-healing properties.

[0013] In some embodiments of the present application, the absorber is one or more of a conductive metal silicide, a conductive metal boride, a conductive non-metal silicide, a conductive non-metal boride, and a conductive elemental silicon.

[0014] In some embodiments of the present application, the conductive metal silicide is TiSi2, MoSi2, the conductive metal boride is ZrB2, the conductive non-metal silicide is SiC, and the conductive non-metal boride is SiB6, B4C.

[0015] In some embodiments of the present application, the particle size of the doped modified high temperature resistant absorbing ceramic and the particle size of the absorber are both less than or equal to 90 μm, and the thickness of the high temperature resistant absorbing coating is greater than or equal to 1 mm and less than or equal to 2 mm.

[0016] According to a second aspect of the present application, a structural component is provided, comprising: a silicon-based ceramic composite material substrate layer; a high-temperature resistant absorbing coating, located on the silicon-based ceramic composite material substrate layer, for protecting the silicon-based ceramic composite material substrate layer and improving the mechanical properties and absorbing properties of the structural component; wherein the high-temperature resistant absorbing coating is the high-temperature resistant absorbing coating with environmental barrier characteristics described in the above embodiment.

[0017] Compared with the prior art, the high temperature resistant wave absorbing coating with environmental barrier characteristics of the present application has the following advantages:

[0018] 1. The high temperature resistant absorbing coating with environmental barrier properties in the present application has excellent environmental barrier properties, which can prevent the silicon-based ceramic composite material substrate layer from being severely corroded, thereby ensuring that the absorbing coating works stably without failure in an extremely corrosive environment, and at the same time has excellent absorbing performance in a high temperature environment.

[0019] 2. The high temperature resistant absorbing coating with environmental barrier properties containing the absorber in the present application also has self-healing properties, which can ensure that after the absorbing coating is mechanically damaged, the damaged part will self-heal instead of forming larger damage, causing the coating to peel off and fail.

[0020] 3. The high temperature resistant absorbing coating with environmental barrier properties in the present application has good high temperature resistance and can work stably for a long time in an environment above 800°C without failure.

[0021] 4. The high temperature resistant and wave absorbing coating with environmental barrier properties in the present application can be prepared by plasma spraying, flame spraying, laser cladding and other methods, and has the advantages of simple preparation process, low equipment requirements and high repeatability.

[0022] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings herein are incorporated into the specification and constitute a part of the specification, illustrate embodiments consistent with the present application, and together with the specification are used to explain the principles of the present application. Obviously, the drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0024] Figure 1The reflection loss curves of the high temperature resistant absorbing coating in the present application after annealing at room temperature and 800°C are shown.

[0025] Figure 2 An electron microscope photograph is shown of the crack healing of the high temperature resistant microwave absorbing coating in the present application after being kept at 1000° C. for three hours.

[0026] Figure 3 The flowchart of the method for preparing the high temperature resistant radar absorbing coating with environmental barrier properties in the present application is schematically shown.

[0027] Figure 4 A schematic diagram of a process for preparing another high temperature resistant radar absorbing coating in the present application is shown schematically.

[0028] Figure 5 The schematic diagram of the structure of the structural parts is shown schematically. DETAILED DESCRIPTION

[0029] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this application will be more comprehensive and complete and fully convey the concept of the example embodiments to those skilled in the art.

[0030] In addition, described feature, structure or characteristic can be combined in one or more embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present application. However, those skilled in the art will appreciate that the technical scheme of the present application can be put into practice without one or more of the specific details, or other methods, components, devices, steps, etc. can be adopted. In other cases, known methods, devices, realizations or operations are not shown or described in detail to avoid blurring the various aspects of the application.

[0031] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0032] In the relevant technologies in this field, as aircraft engines develop towards high efficiency and high thrust-to-weight ratio, traditional nickel-based high-temperature alloys have approached their service temperature limits and can no longer be used as the matrix material for radar-absorbing coatings. The introduction of new material systems is urgent. Silicon-based ceramic composites have become an ideal material to replace traditional nickel-based high-temperature alloys due to their light weight, high strength, and stable high-temperature properties.

[0033] However, since the absorbing coating does not have an environmental barrier function and cannot provide protection for the silicon-based ceramic composite matrix layer, the silicon-based ceramic composite matrix is ​​susceptible to CMAS (CaO-MgO-Al2O3-SiO2) molten salt erosion, aviation fuel additive corrosion and high-temperature water and oxygen corrosion in harsh service environments. Furthermore, when the absorbing coating on the surface of the stealth equipment is mechanically damaged by scratches and bumps, the corrosion rate of the silicon-based ceramic composite matrix layer increases, which will cause the absorbing coating to peel off and fail over a large area, and the absorbing performance will be seriously reduced. Moreover, if the damage cannot be repaired in time, the mechanical properties and absorbing properties of the absorbing coating will also be greatly reduced, or even completely fail, which will lead to a decrease in the stealth performance of the stealth equipment.

[0034] In response to the problems existing in the related technologies, the present application provides a high-temperature resistant absorbing coating with environmental barrier properties and a structural member formed using the high-temperature resistant absorbing coating with environmental barrier properties. The high-temperature resistant absorbing coating with environmental barrier properties can prevent the silicon-based ceramic composite material substrate layer from being eroded by CMAS molten salt, corroded by aviation fuel additives, and corroded by high-temperature water and oxygen, etc. Furthermore, it can also prevent the absorbing coating from large-area peeling and failure, and the degradation of mechanical properties and absorbing properties.

[0035] Next, the high temperature resistant absorbing coating with environmental barrier properties in the embodiment of the present application is described in detail.

[0036] The present application first provides a high temperature resistant absorbing coating with environmental barrier properties, wherein the high temperature resistant absorbing coating is composed of a doped and modified high temperature resistant absorbing ceramic, wherein the conductivity of the doped and modified high temperature resistant absorbing ceramic is greater than or equal to 10 -4 S / cm and less than or equal to 10 -1 S / cm.

[0037] In one or more embodiments of the present application, the doped high temperature resistant absorbing ceramic is: one or more of: doped rare earth monosilicate, doped rare earth pyrosilicate, doped rare earth phosphate, and doped rare earth tantalate. In the embodiments of the present application, the doping ions used for doping and modification are positive ions whose ionic radius is equal to or close to the ionic radius of the doping ions, wherein the doping ions are positive ions in the acid radicals contained in the ceramic matrix forming the doped high temperature resistant absorbing ceramic, for example, when the doped high temperature resistant absorbing ceramic is doped rare earth monosilicate, the ceramic matrix is ​​rare earth monosilicate, and the doping ions are silicon ions, when the doped high temperature resistant absorbing ceramic is doped rare earth phosphate, the ceramic matrix is ​​rare earth phosphate, and the doping ions are phosphorus ions, and so on.

[0038] When the ionic radius of the ion to be doped is not equal to the ionic radius of the doping ion, the deviation rate between the ionic radius of the doping ion and the ionic radius of the doping ion is used to determine whether the ion to be doped can be used to dope the ceramic matrix. Specifically, determine whether the deviation rate is greater than 10%. When the deviation rate is less than or equal to 10%, it indicates that the doping ion can be used to dope the ceramic matrix to form a doped and modified high-temperature resistant absorbing ceramic. When the deviation rate is greater than 10%, it indicates that the doping ion cannot be used to dope the ceramic matrix to form a doped and modified high-temperature resistant absorbing ceramic. For example, Fe 3+ 、Ti 4+ , B 3+ Positively charged ions are used to obtain high temperature resistant microwave absorbing ceramics that are doped and modified.

[0039] In one or more embodiments of the present application, the molecular formula of the doped modified rare earth monosilicate is ReSi 1- X B X O5, the molecular formula of the doped rare earth pyrosilicate is Re2Si 2-Y B Y O7, the molecular formula of the doped rare earth phosphate is ReP 1-X B X O4, the molecular formula of the doped rare earth tantalate is ReTa 1-X B x O4, Re in the above molecular formula is La, Ce, Pr, Sc, Nd, Sm, Eu, Tb, Yb, Y, Ho, Dy, Lu, Tm, Er or Gd; the doping element B is Fe, Ti, B, Co, Mn, P, Ga or Ge; at the same time, X is greater than 0 and less than or equal to 0.5; Y is greater than 0 and less than or equal to 1.

[0040] In one or more embodiments of the present application, the size and structure of the doped ions will affect the lattice parameters and electronic structure of the crystal. Ions of different sizes may cause lattice distortion or change the electronic band structure, thereby affecting the conductive properties. In view of this, in the embodiments of the present application, the particle size of the doped ions can be set to be less than or equal to 90 μm, and of course it can be set to other values ​​according to actual needs. The embodiments of the present application do not specifically limit this. Furthermore, the thickness of the high temperature resistant absorbing coating can also be set according to actual needs. In the embodiments of the present application, the thickness of the high temperature resistant absorbing coating can be set to be greater than or equal to 1 mm and less than or equal to 2 mm.

[0041] In the present application, the conductivity of the ceramic matrix can be changed by doping the ceramic matrix. At the same time, the absorbing performance of the ceramic matrix can be adjusted by adjusting the doping concentration of the doped ions to obtain a doped high temperature resistant absorbing ceramic. When the conductivity of the doped high temperature resistant absorbing ceramic is greater than or equal to 10 -4 S / cm and less than or equal to 10 -1 S / cm, the high temperature resistant absorbing coating can show excellent absorbing performance and also has excellent environmental barrier properties. That is to say, the doped and modified high temperature resistant absorbing ceramics are formed on the silicon-based ceramic composite matrix layer. On the one hand, it can prevent the silicon-based ceramic composite matrix layer from being eroded by CMAS molten salt, corroded by aviation fuel additives, and corroded by high temperature water and oxygen, thereby improving the mechanical properties and service life of the structural parts; on the other hand, it can make the structural parts have excellent absorbing performance in high temperature environment and improve the stealth performance of the structural parts.

[0042] Next, the structure and performance of the high temperature resistant absorbing coating with environmental barrier characteristics in the embodiments of the present application are described through four groups of embodiments, as shown in Table 1:

[0043] Table 1 Coating composition, thickness, temperature resistance and microwave absorption performance corresponding to each embodiment

[0044]

[0045] As shown in Table 1, the high temperature absorbing coating formed by the doped and modified high temperature absorbing ceramics has both high temperature resistance (≥800°C) and excellent absorbing performance. At the same time, the high temperature resistant ceramics as the base material themselves have excellent environmental barrier properties. Therefore, the high temperature absorbing coating formed by the doped and modified high temperature absorbing ceramics can be used as an environmental barrier coating to protect the silicon-based ceramic composite material base layer, and can also enable the target equipment to have excellent absorbing performance and stability in a high temperature environment above 800°C.

[0046] In one or more embodiments of the present application, the absorbing coating is the outermost layer of the stealth equipment in contact with the environment. In addition to being affected by high temperature, it will also produce scratches and cracks due to collision and friction. If the scratches and cracks are not treated, the silicon-based ceramic composite matrix layer will be corroded, and the mechanical properties and absorbing properties of the absorbing coating will also be greatly reduced, or even fail. Therefore, the doped and modified high-temperature resistant absorbing ceramic can be used as the matrix material, and an absorbing agent can be added therein. When scratches and cracks are produced on the absorbing coating, the scratches and cracks will heal themselves under the action of the absorbing agent, thereby improving the protective effect on the silicon-based ceramic composite matrix layer, and at the same time improving the absorbing properties and mechanical properties of the high-temperature resistant absorbing coating.

[0047] In one or more embodiments of the present application, the composition and type of the doped and modified high temperature resistant absorbing ceramic material are the same as those of the doped and modified high temperature resistant absorbing ceramic material in the above embodiments, and are not described in detail here. The absorber may be one or more of a conductive metal silicide, a conductive metal boride, a conductive non-metal silicide, a conductive non-metal boride, and a conductive elemental silicon. Exemplarily, the conductive metal silicide may be TiSi2, MoSi2, etc., the conductive metal boride may be ZrB2, etc., the conductive non-metal silicide may be SiC, etc., and the conductive non-metal boride may be SiB6, B4C, etc.

[0048] It can be understood that in the embodiment of the present application, by adding conductive absorbing agents such as silicide, boride, elemental silicon, etc. to the high temperature resistant absorbing ceramic, under the action of high temperature, silicide, boride or elemental silicon can be oxidized to produce amorphous silicon dioxide, boron oxide, etc. with good fluidity. These oxides can form a layer of dense glassy substance on the surface of the absorbing coating. When there are scratches and cracks on the absorbing coating, the glassy substance can fill the cracks to achieve self-healing of the absorbing coating and avoid corrosion of the substrate layer of the silicon-based ceramic composite material. At the same time, the glassy substance can also isolate oxygen to prevent the absorbing coating from being oxidized, thereby improving the mechanical properties of the absorbing coating.

[0049] In one or more embodiments of the present application, in order to improve the absorbing performance and mechanical properties of the absorbing coating while reducing the weight of the structural member, the particle size of the doped and modified high temperature resistant absorbing ceramic and the absorbing agent can be set to be less than or equal to 90 μm, and the thickness of the high temperature resistant absorbing coating can be set to be greater than or equal to 1 mm and less than or equal to 2 mm. Of course, the particle size of the doped and modified high temperature resistant absorbing ceramic and the absorbing agent, and the thickness of the high temperature resistant absorbing coating can also be set to other values ​​according to actual needs, and the embodiments of the present application are not specifically limited to this.

[0050] Furthermore, the mass ratio of the doped and modified high-temperature resistant absorbing ceramic and the absorbing agent in the high-temperature resistant absorbing coating can be set to (7-9):(3-1) to obtain a high-temperature resistant absorbing coating with excellent absorbing performance.

[0051] In one or more embodiments of the present application, since the magnetism of common absorbing materials disappears in high temperature scenarios above 800°C, in order to improve the absorbing performance of the absorbing coating, the conductive absorbing agent in the embodiments of the present application can select a conductive absorbing material with a melting point higher than 800°C to improve the stability and absorbing performance of the absorbing coating in high temperature scenarios above 800°C.

[0052] The absorbent with high temperature resistance and self-healing properties in the present application not only has a high conductivity at high temperature, and can be used as a radar wave absorbent in a high temperature environment above 800°C, but also has a certain antioxidant ability, which improves the stability and service life of the coating's self-healing performance. Furthermore, the high temperature resistant absorbing coating with self-healing and environmental barrier properties composed of a ceramic matrix with environmental barrier properties and an absorbent with high temperature resistance and self-healing properties can take into account good corrosion resistance, good self-healing ability, good high temperature resistance and good absorbing performance.

[0053] Next, the structure and performance of the high temperature resistant absorbing coating with environmental barrier characteristics in the embodiments of the present application are described through eleven groups of embodiments, as shown in Table 2:

[0054] Table 2 Coating composition, thickness, temperature resistance and performance corresponding to each embodiment

[0055]

[0056] Note: Cracks are formed by applying external force to the absorbing coating to break it; the crack healing condition is obtained by heating the absorbing coating to the self-healing temperature at a heating rate of 5℃ / min and keeping it at this temperature for a certain period of time, and then taking electron microscope photos to observe.

[0057] According to Table 2, the absorbing coatings corresponding to each group of embodiments have an X-band absorption bandwidth of more than 1.4 GHz and up to 1.7 GHZ under a high temperature environment of more than 850°C. Compared with the absorbing coatings formed by only using doped and modified high-temperature resistant absorbing ceramics, the temperature resistance is improved and the absorbing performance is also improved, indicating that the absorbing coatings composed of doped and modified high-temperature resistant absorbing ceramics and absorbing agents have environmental barrier characteristics and high-temperature resistant wave absorbing characteristics. At the same time, the absorbing coatings corresponding to each group of embodiments can also achieve self-healing under certain temperature conditions, and the self-healing time is ≤4h. As shown in Example 9, when the absorbing coating is mechanically damaged, it only takes 1h to heal the cracks under the condition of 700±50°C, indicating that the absorbing coatings composed of doped and modified high-temperature resistant absorbing ceramics and absorbing agents in the embodiments of the present application have both environmental barrier characteristics, high-temperature resistant wave absorbing characteristics and self-healing characteristics.

[0058] Figure 1 The reflection loss curves of the high temperature resistant absorbing coating corresponding to Example 1 in Table 2 after annealing at room temperature and 800°C are shown. Figure 1As shown, curve A is the reflection loss curve of the absorbing coating at room temperature, and curve B is the reflection loss curve of the absorbing coating after annealing in air at 800°C for three hours. Analysis shows that the effective absorption bandwidth of the absorbing coating at room temperature is greater than 2.1GHz. After annealing in air at 800°C for three hours, the effective absorption bandwidth is still 1.3GHZ, with a small decrease. This shows that the absorbing coating has a good microwave absorption effect whether it is annealed at room temperature or in air at 800°C for three hours. This also further illustrates that the high-temperature resistant absorbing coating with environmental barrier characteristics in the embodiment of the present application has excellent absorbing performance in a high-temperature environment.

[0059] Figure 2 The electron microscope photographs of the crack healing of the high temperature resistant absorbing coating corresponding to Example 1 in Table 2 after being kept at 1000° C. for three hours are shown. Figure 2 As shown, the cracks are filled and have a good self-healing effect, which indicates that the high temperature resistant absorbing coating with environmental barrier properties containing the absorber in the embodiment of the present application has good crack healing performance.

[0060] The present application also provides a method for preparing a high temperature resistant radar absorbing coating having environmental barrier properties. Figure 3 The schematic diagram of the process of preparing the high temperature resistant wave absorbing coating with environmental barrier properties is shown schematically, as shown in FIG. Figure 3 As shown, the preparation method comprises:

[0061] Step S310: weighing a preset mass of doped and modified high temperature resistant microwave absorbing ceramics;

[0062] Step S320: preparing microwave absorbing ceramic powder by conventional spray drying method;

[0063] Step S330: using the absorbing ceramic powder as a raw material, preparing a high temperature resistant absorbing coating having environmental barrier properties on the pretreated silicon-based ceramic composite material substrate layer.

[0064] Furthermore, we can also use Figure 3 The doped modified high temperature resistant absorbing ceramics and the absorbing agent with self-healing properties form a high temperature resistant absorbing coating to improve the absorbing performance and self-healing performance of the high temperature resistant absorbing coating, thereby increasing the service life of the high temperature resistant absorbing coating.

[0065] Figure 4 A schematic diagram of another method for preparing a high temperature resistant radar absorbing coating is shown schematically. Figure 4 As shown, the preparation method comprises:

[0066] Step S410: weighing the doped and modified high temperature resistant absorbing ceramic and the absorbing agent according to a preset mass ratio;

[0067] Step S420: preparing composite powder by conventional spray drying method;

[0068] Step S430: using the composite powder as a raw material, preparing a high temperature resistant wave absorbing coating having self-healing and environmental barrier properties on the pretreated silicon-based ceramic composite material substrate layer.

[0069] Next, the preparation method and performance of the high temperature resistant radar absorbing coating in the present application are described in detail.

[0070] In one or more embodiments of the present application, when a conventional spray drying method is used to prepare absorbing ceramic powder or composite powder, it is first necessary to ball-mill the doped and modified high-temperature resistant absorbing ceramic, or the doped and modified high-temperature resistant absorbing ceramic and the absorber to obtain a slurry, and then granulate the slurry to obtain the absorbing ceramic powder or composite powder.

[0071] During ball milling, liquid grinding aids need to be added. In the embodiment of the present application, when the high temperature absorbing coating does not contain an absorber, the doped high temperature absorbing ceramic and the liquid grinding aid are weighed according to a preset mass ratio, wherein the mass percentage of the liquid grinding aid is greater than or equal to the mass percentage of the doped high temperature absorbing ceramic; when the high temperature absorbing coating contains an absorber, the doped high temperature absorbing ceramic and the absorber are first weighed according to the first mass ratio, and then the liquid grinding aid is weighed according to the second mass ratio, the mass of the solid substances corresponding to the doped high temperature absorbing ceramic and the absorber. Among them, the mass percentage of the doped high temperature absorbing ceramic in the first mass ratio is greater than the mass percentage of the absorber, and the mass percentage of the liquid grinding aid in the second mass ratio is greater than or equal to the mass percentage of the solid substances corresponding to the doped high temperature absorbing ceramic and the absorber. Further, the ratio of the mass of the liquid grinding aid to the mass of the solid substance is 1:1 to 2:1, and of course it can also be set to other ratios according to actual needs, and the embodiment of the present application does not specifically limit this.

[0072] In one embodiment of the present application, after weighing the doped and modified high temperature resistant absorbing ceramic, the absorbing agent and the liquid grinding aid, the doped and modified high temperature resistant absorbing ceramic, the absorbing agent and the liquid grinding aid can be placed in a ball mill for ball milling to obtain a slurry. The ball milling parameters of the ball mill can be set to: a rotation speed of 40 to 80 r / min and a ball milling time of 8 to 24 hours.

[0073] After obtaining the slurry, the slurry can be used as a raw material and granulated using a spray granulator to obtain absorbing ceramic powder or composite powder. The specific granulation process is: first, add 2wt% to 5wt% of polyvinyl alcohol or sodium carboxymethyl cellulose aqueous solution to the slurry, drip 1 to 5 drops of defoaming agent, and stir evenly; then, pass the stirred slurry into a spray granulator configured with granulation parameters to obtain powder; wherein the granulation parameters can be specifically set to: air inlet temperature 280 to 380°C, air outlet temperature 70 to 140°C, peristaltic pump speed 18 to 25r / min; finally, use a 100 to 200 mesh sieve to sieve the powder, and dry the sieved powder in an environment of 60 to 150°C for 2 to 5 hours to obtain absorbing ceramic powder or mixed powder.

[0074] In one embodiment of the present application, after obtaining the absorbing ceramic powder or composite powder, it can be used as a raw material to prepare a high temperature absorbing coating with environmental barrier properties on a silicon-based ceramic composite material substrate layer. It should be noted that before preparing the coating, the silicon-based ceramic composite material substrate layer needs to be pretreated. Specifically, the silicon-based ceramic composite material substrate layer can be sandblasted and cleaned to remove impurities on the surface of the silicon-based ceramic composite material substrate layer and improve the surface roughness, thereby improving the bonding strength between the absorbing coating and the silicon-based ceramic composite material substrate layer.

[0075] In one or more embodiments of the present application, any method can be used to prepare a coating formed by absorbing ceramic powder or composite powder on a pretreated silicon-based ceramic composite material substrate layer. For example, a high-temperature resistant absorbing coating can be formed on a pretreated silicon-based ceramic composite material substrate layer by a spraying method such as plasma spraying or flame spraying. A high-temperature resistant absorbing coating can also be formed on a pretreated silicon-based ceramic composite material substrate layer by a laser cladding method. A high-temperature resistant absorbing coating can also be formed on a pretreated silicon-based ceramic composite material substrate layer by a screen printing method, and so on. The embodiments of the present application do not specifically limit this.

[0076] Next, the performance of the high temperature resistant radar absorbing coating with environmental barrier properties in the embodiments of the present application is described through two groups of comparative examples.

[0077] Comparative Example 1

[0078] A 1.3 mm thick absorbing coating is formed by using 20 wt% B4C and 80 wt% Al2O3. The absorbing coating can work in an environment not exceeding 500°C. If it exceeds 500°C, the absorbing performance of the absorbing coating will disappear. In an environment of 450±50°C, the X-band absorption bandwidth of the absorbing coating is 1.7 GHz. Analysis shows that compared with the absorbing coating in Example 1, the coating cannot work stably in a high temperature environment above 800°C, and has poor resistance to CMAS corrosion, thereby failing to improve the stability and service life of the structural parts.

[0079] Comparative Example 2

[0080] A 1.3 mm thick absorbing coating is formed by using 15 wt% MWCNTs and 85 wt% Al2O3. The absorbing coating can work in an environment not exceeding 450°C. If it exceeds 450°C, the absorbing performance of the absorbing coating will disappear. In an environment of 400±50°C, the X-band absorption bandwidth of the absorbing coating is 1.9 GHz. Similar to the absorbing coating in Comparative Example 1, the absorbing coating cannot work stably in a high temperature environment above 800°C, and has poor resistance to CMAS corrosion, and cannot achieve a good protective effect on the substrate formed by the carbon-carbon composite material, thereby failing to improve the stability and service life of the target.

[0081] The high temperature resistant absorbing coating in the present application is composed of doped modified high temperature resistant absorbing ceramics, or is composed of doped modified high temperature resistant absorbing ceramics and absorbing agents. When the absorbing coating is composed of doped modified high temperature resistant absorbing ceramics, the absorbing coating has both environmental barrier properties and high temperature resistant absorbing properties. When the absorbing coating is composed of doped modified high temperature resistant absorbing ceramics and absorbing agents, the absorbing coating has self-healing properties, environmental barrier properties and high temperature resistant absorbing properties. The high temperature resistant absorbing coating with environmental barrier properties in the present application can achieve better protection for the silicon-based ceramic composite material substrate layer, preventing it from being threatened by the erosion of CMAS molten salt and high temperature water and oxygen corrosion, so that the prepared absorbing coating is not easy to fall off or crack, and has a longer service life. In addition, since the high-temperature resistant absorbing coating with environmental barrier properties in the present application can be used in a high-temperature environment above 800°C, the absorbing coating in the present application has a wide range of applications and can be applied to substrates formed by materials such as silicon-based ceramic composite materials that have the characteristics of low density, high temperature resistance, good mechanical properties, and poor resistance to CMAS and water-oxygen corrosion. Specifically, it can be applied to equipment that requires stealth to improve the stealth performance and service life of the equipment.

[0082] Finally, the present application also provides a structural component, which is a part of the target equipment. Figure 5 The schematic diagram of the structure of the structural parts is shown schematically. Figure 5As shown, the structural member sequentially comprises a silicon-based ceramic composite material substrate layer 501 and a high temperature resistant absorbing coating 502. The high temperature resistant absorbing coating 502 is a high temperature resistant absorbing coating with environmental barrier characteristics in the embodiment of the present application or a high temperature resistant absorbing coating with environmental barrier characteristics prepared according to the preparation method of the high temperature resistant absorbing coating with environmental barrier characteristics in the embodiment of the present application, and is located on the silicon-based ceramic composite material substrate layer 501, and is used to protect the silicon-based ceramic composite material substrate layer and improve the mechanical properties and absorbing properties of the structural member.

[0083] The above are only preferred embodiments of the present application, and do not limit the scope of the present application. For those skilled in the art, the present application may have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the scope of the patent protection of the present application.

Claims

1. A high temperature resistant radar absorbing coating with environmental barrier properties, characterized in that: The high temperature resistant wave absorbing coating is composed of doped and modified high temperature resistant wave absorbing ceramics; The electrical conductivity of the doped and modified high temperature resistant wave absorbing ceramic is greater than or equal to 10 -4 S / cm and less than or equal to 10 - 1 S / cm.

2. The high temperature resistant radar absorbing coating with environmental barrier properties according to claim 1, characterized in that: The doped and modified high temperature resistant wave absorbing ceramic is one or more of: doped and modified rare earth monosilicate, doped and modified rare earth pyrosilicate, doped and modified rare earth phosphate, and doped and modified rare earth tantalate.

3. The high temperature resistant radar absorbing coating with environmental barrier properties according to claim 2, characterized in that: The molecular formula of the doped and modified rare earth monosilicate is ReSi 1-X B X O5, the molecular formula of the doped modified rare earth pyrosilicate is Re2Si 2-Y B Y O7, the molecular formula of the doped modified rare earth phosphate is ReP 1-X B X O4, the molecular formula of the doped and modified rare earth tantalate is ReTa 1-X B x O4; Among them, Re is La, Ce, Pr, Sc, Nd, Sm, Eu, Tb, Yb, Y, Ho, Dy, Lu, Tm, Er or Gd; B is Fe, Ti, B, Co, Mn, P, Ga or Ge; X is greater than 0 and less than or equal to 0.5; Y is greater than 0 and less than or equal to 1.

4. The high temperature resistant radar absorbing coating with environmental barrier properties according to any one of claims 1 to 3, characterized in that: The particle size of the doped and modified high temperature resistant wave absorbing ceramic is less than or equal to 90 μm, and the thickness of the high temperature resistant wave absorbing coating is greater than or equal to 1 mm and less than or equal to 2 mm.

5. The high temperature resistant radar absorbing coating with environmental barrier properties according to claim 1, characterized in that: The high temperature resistant wave absorbing coating is composed of the doped and modified high temperature resistant wave absorbing ceramic and the wave absorbing agent, so that the high temperature resistant wave absorbing coating has both environmental barrier properties and self-healing properties.

6. The high temperature resistant radar absorbing coating with environmental barrier properties according to claim 5, characterized in that: The wave absorber is one or more of a conductive metal silicide, a conductive metal boride, a conductive non-metal silicide, a conductive non-metal boride, and a conductive elemental silicon.

7. The high temperature resistant radar absorbing coating with environmental barrier properties according to claim 6, characterized in that: The conductive metal silicide is TiSi2 and MoSi2, the conductive metal boride is ZrB2, the conductive non-metal silicide is SiC, and the conductive non-metal boride is SiB6 and B4C.

8. The high temperature resistant radar absorbing coating with environmental barrier properties according to any one of claims 5 to 7, characterized in that: The particle size of the doped and modified high temperature resistant absorbing ceramic and the particle size of the absorbing agent are both less than or equal to 90 μm, and the thickness of the high temperature resistant absorbing coating is greater than or equal to 1 mm and less than or equal to 2 mm.

9. A structural member, characterized in that: include: Silicon-based ceramic composite material substrate layer; A high temperature resistant wave absorbing coating, located on the silicon-based ceramic composite material substrate layer, for protecting the silicon-based ceramic composite material substrate layer and improving the mechanical properties and wave absorbing properties of the structural component; Wherein, the high temperature resistant radar absorbing coating is the high temperature resistant radar absorbing coating with environmental barrier properties as described in any one of claims 1 to 8.

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