High-temperature-resistant bicontinuous structure spherical wave-absorbing powder and preparation method thereof

Abstract

The application relates to the technical field of high-temperature wave-absorbing coating materials, in particular to a high-temperature-resistant bicontinuous structure spherical wave-absorbing powder and a preparation method thereof. The wave-absorbing powder comprises mullite powder and SiCN powder, and the mass ratio of the mullite powder to the SiCN powder is 1.5-9:1. The high-temperature-resistant bicontinuous structure spherical wave-absorbing powder and the preparation method thereof aim to solve the problem that the existing SiC f / SiC ceramic matrix composite material surface-prepared high-temperature wave-absorbing coating material needs to use a thermal matching layer to enhance the thermal shock resistance of the coating, thereby increasing the overall weight of the coating.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high-temperature wave-absorbing coating materials, and particularly relates to a high-temperature-resistant bicontinuous structure spherical wave-absorbing powder and a preparation method thereof. BACKGROUND

[0002] In recent years, the research on microwave absorbing materials has promoted the better use of microwave technology in civil communication and other fields. Through further development, these microwave absorbing materials become thinner, lighter and more efficient. The wave-absorbing coating is an important form of the application of microwave absorbing materials, and has the advantages of convenient construction, good wave-absorbing performance and not easy to affect the original state of the base material. However, most of the current wave-absorbing materials effective at room temperature are invalid due to the loss of magnetism at high temperature (> 700K). Therefore, it is urgent to develop high-temperature-resistant wave-absorbing coating materials as a key technology. At the same time, an ideal high-temperature-resistant wave-absorbing coating needs to be thin, strong in absorption and good in thermal shock resistance, so as to better meet the use requirements.

[0003] He Qing et al. of China Agricultural Mechanization Science and Technology Institute used phosphate glass binder and dispersant, used modified β-SiC material as an absorber, prepared a Ni-Al metal bonding layer with a thickness of about 50 μm by arc spraying to reduce the difference in thermal expansion coefficient between the wave-absorbing coating and the substrate, and prepared a wave-absorbing coating on the surface of carbon steel by flame spraying method, and the thickness of the coating was controlled at about 1 mm. Lv Yanhong of China Steel Research Technology Group Co., Ltd. applied mechanical chemical method to coat nano silicon carbide on the surface of micron nickel powder to prepare nano composite nickel powder wave-absorbing material, and prepared a nano composite nickel powder / carbonyl iron powder double-layer wave-absorbing coating on the surface of aluminum plate by plasma spraying process, and studied the influence of the content change of SiC in the composite material on the wave-absorbing performance of the coating. M. Bégard et al. synthesized Co, Ti substituted barium ferrite BaCoTiFe 10 O 19 by using BaCO3, Co3O4, TiO2 and Fe2O3 as raw materials through solid state reaction, and prepared a wave-absorbing coating on a glass ceramic substrate by high-speed flame spraying (HVOF) and atmospheric plasma spraying (APS), and the research results show that the barium ferrite coating prepared by thermal spraying is suitable for use as a microwave and millimeter wave absorbing material.

[0004] High-temperature wave-absorbing coating materials are mainly ceramic materials. Since the ceramic has poor heat conduction performance, rapid temperature rise or drop can form a temperature difference inside the ceramic. In order to improve the wave-absorbing performance, the coating is often thick, and a large thermal stress is more likely to occur inside the coating, which can cause problems such as layering, cracking and adhesion loss of the coating, and even damage and peeling, thereby restricting the performance of the wave-absorbing material. The main measure taken at the present stage is to select a material with a suitable thermal expansion coefficient as a transition layer for different substrates. However, this solution increases the thickness and weight of the coating, which does not meet the weight reduction index of the coating, and the research on coating materials suitable for SiCf / SiC ceramic matrix composites is relatively less.

[0005] Therefore, the inventors provide a high-temperature-resistant bicontinuous structure spherical wave-absorbing powder and a preparation method thereof. SUMMARY

[0006] (1) Technical problems to be solved

[0007] The embodiments of the present application provide a high-temperature-resistant bicontinuous structure spherical wave-absorbing powder and a preparation method thereof, which solve the technical problem that the preparation of a high-temperature-resistant wave-absorbing coating material on the surface of a SiC f / SiC ceramic matrix composite material increases the overall weight of the coating due to the need for a thermal matching layer to enhance the thermal shock resistance of the coating.

[0008] (2) Technical solutions

[0009] The first aspect of the present application provides a high-temperature-resistant bicontinuous structure spherical wave-absorbing powder, which comprises mullite powder and SiCN powder, and the mass ratio of the mullite powder to the SiCN powder is 1.5-9:1.

[0010] Further, the particle size of the SiCN powder is 1-10 μm.

[0011] The second aspect of the present application provides a preparation method of a high-temperature-resistant bicontinuous structure spherical wave-absorbing powder, which comprises the following steps:

[0012] The mullite powder, the SiCN powder, the binder and the deionized water are uniformly mixed to obtain a suspension;

[0013] The suspension is prepared into a powder by a spray drying granulation process, and the obtained powder is subjected to a drying treatment to obtain a mullite / SiCN bicontinuous structure composite powder.

[0014] Further, the particle size of the SiCN powder is 1-10 μm.

[0015] Further, the uniformly mixed mullite powder, SiCN powder, binder and deionized water to obtain a suspension are specifically as follows:

[0016] The suspension is obtained by mixing in a ball milling manner, the ball milling speed is 150 rpm-420 rpm, the ball milling time is 2.5 h-5 h, and the ball-to-material ratio is 4-6:1.

[0017] Further, the mass percentage of the binder in the suspension is 0.21%-0.54%, the sum of the mass percentages of the mullite powder and the SiCN powder is 30%-50%, and the mass ratio of the mullite powder to the SiCN powder is 1.5-9:1.

[0018] Further, the parameters of the spray drying granulation process are as follows: the inlet temperature is 200-300 DEG C, the outlet temperature is 120-160 DEG C, the nozzle rotation speed is 25-40 Hz, and the peristaltic pump rotation speed is 30-45 rpm.

[0019] Further, the obtained powder is subjected to a drying treatment, specifically:

[0020] The powder is dried at 100-150 DEG C for 20-30 h.

[0021] Further, after the drying treatment, the powder is subjected to a screening test, and a mullite / SiCN double-continuous-structure composite powder with a particle size of 30-80 mu m is obtained.

[0022] Further, the binder is polyvinyl alcohol.

[0023] (3) Beneficial effects

[0024] In summary, the mullite phase and the SiCN phase are both uniformly combined with SiC f / SiC composite material has good thermal matching, and the prepared coating and SiC f / SiC ceramic matrix composite substrate have good thermal matching performance, without the need for further introduction of a transition layer, which is conducive to the lightweight of the material; at the same time, by adjusting the component content and the particle size of the powder, a double-continuous-structure composite powder is realized, so that the mullite phase for impedance matching and the SiCN phase as a wave absorber can be uniformly combined, the prepared coating of the material meets the impedance matching requirement and has good wave absorption performance. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments of the present application will be briefly introduced as follows. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0026] Figure 1is a flowchart of a preparation method of a high-temperature-resistant bicontinuous structure spherical wave-absorbing powder provided by an embodiment of the application.

[0027] Figure 2 is a micro-morphology diagram of the high-temperature-resistant bicontinuous structure spherical wave-absorbing powder.

[0028] Figure 3 is Figure 2 is a partial enlarged view of the micro-morphology of the high-temperature-resistant bicontinuous structure spherical wave-absorbing powder. DETAILED DESCRIPTION

[0029] The embodiments of the application will be further described in detail below with reference to the accompanying drawings and embodiments. The detailed description of the following embodiments and the accompanying drawings are used to exemplarily illustrate the principles of the application, but cannot be used to limit the scope of the application, that is, the application is not limited to the described embodiments.

[0030] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0031] Figure 2 is a micro-morphology diagram of a high-temperature-resistant bicontinuous structure spherical wave-absorbing powder provided by an embodiment of the application, which comprises mullite powder and SiCN powder, the mass ratio of the mullite powder to the SiCN powder is 1.5-9:1, and the particle size of the SiCN powder is 1-10 microns.

[0032] In the above embodiment, by testing the electromagnetic parameters of a plurality of selected powders, the wave-absorbing coating matrix is preferably mullite phase, and the wave-absorbing agent is SiCN, and the mullite phase and the SiCN phase have high-temperature resistance and oxidation resistance, which are suitable for preparing a high-temperature-resistant coating, and the mullite phase and the SiCN phase with a suitable particle size are screened, the mullite phase is attached around the SiCN phase to form a bicontinuous structure, which is beneficial to the wave-absorbing performance of the SiCN phase, the SiCN phase is prepared by self-cracking of the research group and has process adjustability, and different cracking temperatures have different performances.

[0033] The mullite powder, the SiCN powder and the SiC fThe SiC ceramic matrix composite has good thermal matching performance, is not easy to crack, has strong adhesion, and does not need to introduce a transition layer, so that the problem of quality increase caused by the transition layer can be avoided. According to the electromagnetic wave transmission line theory, the material system is creatively optimized, including adjusting and controlling the component content and the particle size of the powder and the like. The component and the particle size have a decisive influence on the structure of the composite material and the subsequent coating wave absorption performance. By adjusting the spatial impedance matching and improving the dispersion state of the powder, the double-continuous structure of the composite powder can be realized. The double-continuous structure can fully play the impedance matching performance of the mullite phase and the wave absorption performance of the SiCN phase, so that the coating has good wave absorption performance.

[0034] The double-continuous spherical structure wave absorption powder component has good high-temperature stability and has great application potential in high-temperature environments (800 DEG C and above).

[0035] The double-continuous structure spherical wave absorption powder has good fluidity and uniform composition distribution, is beneficial to plasma spraying, and the prepared coating material is more uniformly distributed, which is beneficial to reducing internal defects of the coating.

[0036] Figure 1 is a flowchart of a preparation method of a high-temperature-resistant double-continuous structure spherical wave absorption powder provided by an embodiment of the present application, as shown in Figure 1 The method can include the following steps:

[0037] S100, mullite powder, SiCN powder, a binder and deionized water are uniformly mixed to obtain a suspension;

[0038] S200, the suspension is prepared into a powder by using a spray drying granulation process, and the obtained powder is subjected to drying treatment to obtain a mullite / SiCN double-continuous structure composite powder.

[0039] In the above embodiment, the magnetic absorption agent is easy to lose magnetism at high temperature and thus loses wave absorption performance, and the powder component has good high-temperature stability and has great application potential in high-temperature environments (800 DEG C and above). The preparation process of the spherical wave absorption powder is simple and convenient, and is easy to realize mass production.

[0040] As an optional embodiment, the mullite powder, the SiCN powder, the binder and the deionized water are uniformly mixed to obtain a suspension, specifically: the suspension is obtained by using ball milling, the ball milling speed is 150 rpm to 420 rpm, the ball milling time is 2.5 h to 5 h, and the ball-to-material ratio is 4 to 6:1. The specific process parameters of the ball milling are specifically selected according to the specific component and content of the suspension selected by the present application.

[0041] As an optional implementation, the mass percentage of the binder in the suspension is 0.21% to 0.54%, the sum of the mass percentages of the mullite powder and the SiCN powder is 30% to 50%, and the mass ratio of the mullite powder to the SiCN powder is 1.5 to 9:1. The component content of the suspension is specifically selected to facilitate the preparation of the high-temperature-resistant double-continuous-structure spherical wave-absorbing powder and is greatly different from the existing high-temperature wave-absorbing coating material, so as to ensure that the mullite phase serving as an impedance matching agent and the SiCN phase serving as a wave-absorbing agent can be homogeneously compounded.

[0042] As an optional implementation, the parameters of the spray drying granulation process are as follows: an inlet temperature of 200°C to 300°C, an outlet temperature of 120°C to 160°C, a nozzle rotation speed of 25 Hz to 40 Hz, and a peristaltic pump rotation speed of 30 rpm to 45 rpm. The parameters of the spray drying granulation process are specifically selected according to the specific components and content of the suspension selected in the application.

[0043] As an optional implementation, the obtained powder is subjected to a drying treatment, specifically, the powder is dried at 100°C to 150°C for 20 h to 30 h. The parameters of the drying treatment process are specifically selected according to the specific components and content of the powder selected in the application.

[0044] As an optional implementation, the mullite / SiCN double-continuous-structure composite powder with a particle size of 30 μm to 80 μm is obtained after the drying treatment and the inspection screening. Specifically, the screening of the particle size range of the mullite / SiCN double-continuous-structure composite powder is mainly to facilitate the preparation of the wave-absorbing coating by spray coating of the powder.

[0045] As an optional implementation, the binder is polyvinyl alcohol (PVA). The specific type of the binder is not limited as long as the binder can satisfy the mutual adhesion of the mullite powder and the SiCN powder in the suspension.

[0046] Example 1

[0047] (1) 268 g of mullite powder, 32 g of SiCN powder, 1.5 g of PVA (polyvinyl alcohol), and 450 g of deionized water are added into a ball mill tank, the ball-to-material ratio is 5:1, the ball milling is performed at a rotation speed of 200 rpm for 4.5 h, the components are uniformly mixed, and a suspension is obtained;

[0048] (2) The suspension is transferred to a spray drying granulation tower for powder preparation. The prepared powder is dried in an oven at 110°C for 28h, and is sieved to obtain mullite / SiCN bicontinuous structure composite powder with a particle size of 30-80μm.

[0049] The spray drying granulation process parameters are as follows: inlet temperature 220°C, outlet temperature 150°C, nozzle rotation speed 35Hz, and peristaltic pump rotation speed 40rpm.

[0050] It should be noted that each of the embodiments in the present specification is described in a progressive manner, and the same or similar parts between the embodiments can be mutually referred to. Each of the embodiments mainly describes the differences from other embodiments. The present application is not limited to the specific steps and structures described above and shown in the drawings. Moreover, for the sake of brevity, detailed descriptions of known methods and techniques are omitted herein.

[0051] The above is merely an embodiment of the present application, and is not limited to the present application. The present application can have various modifications and changes for those skilled in the art without departing from the scope of the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application shall be included in the scope of claims of the present application.

Claims

1. A high-temperature resistant, dual-continuous structure spherical microwave absorbing powder, characterized in that, It includes mullite powder and SiCN powder, wherein the mass ratio of mullite powder to SiCN powder is 1.5 to 9:1, and the mullite phase is attached to the SiCN phase to form a bicontinuous structure.

2. The high-temperature resistant, dual-continuous structure spherical microwave absorbing powder according to claim 1, characterized in that, The particle size of the SiCN powder is 1–10 μm.

3. A method for preparing high-temperature resistant, dual-continuous structure spherical microwave absorbing powder as described in any one of claims 1-2, characterized in that, The method includes the following steps: Mullite powder, SiCN powder, binder and deionized water are mixed evenly to obtain a suspension; The suspension was prepared into powder by spray drying granulation process, and the obtained powder was dried to obtain mullite / SiCN dual continuous structure composite powder.

4. The method for preparing high-temperature resistant, dual-continuous structure spherical microwave absorbing powder according to claim 3, characterized in that, The particle size of the SiCN powder is 1–10 μm.

5. The method for preparing high-temperature resistant, dual-continuous structure spherical microwave absorbing powder according to claim 3, characterized in that, The process of uniformly mixing mullite powder, SiCN powder, binder, and deionized water to obtain a suspension is as follows: The suspension was obtained by ball milling at a speed of 150 rpm to 420 rpm for 2.5 h to 5 h and a ball-to-material ratio of 4 to 6:

1.

6. The method for preparing high-temperature resistant, dual-continuous structure spherical microwave absorbing powder according to claim 3, characterized in that, The mass percentage of the binder in the suspension is 0.21% to 0.54%, the sum of the mass percentages of the mullite powder and the SiCN powder is 30% to 50%, and the mass ratio of the mullite powder to the SiCN powder is 1.5 to 9:

1.

7. The method for preparing high-temperature resistant, dual-continuous structure spherical microwave absorbing powder according to claim 3, characterized in that, The parameters of the spray drying granulation process are: inlet temperature 200℃~300℃, outlet temperature 120℃~160℃, nozzle speed 25Hz~40Hz, and peristaltic pump speed 30rpm~45rpm.

8. The method for preparing high-temperature resistant, dual-continuous structure spherical microwave absorbing powder according to claim 3, characterized in that, The process of drying the obtained powder specifically involves: The powder is dried at 100℃~150℃ for 20h~30h.

9. The method for preparing high-temperature resistant, dual-continuous structure spherical microwave absorbing powder according to claim 3, characterized in that, After drying and sieving, mullite / SiCN bicontinuous structure composite powder with a particle size of 30μm to 80μm was obtained.

10. The method for preparing high-temperature resistant, dual-continuous structure spherical microwave absorbing powder according to any one of claims 3-9, characterized in that, The adhesive is polyvinyl alcohol.

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