High-temperature-resistant wave-absorbing composite material and preparation method thereof

Abstract

The invention relates to a high-temperature-resistant wave-absorbing composite material and a preparation method thereof. The high-temperature-resistant wave-absorbing composite material comprises a resin base material and calcium manganate ceramic powder dispersed in the resin base material, and the resin matrix is polysilicon aryne resin PSAE or paraffin.

Description

Technical Field

[0001] The invention relates to a high temperature-resistant wave-absorbing composite material and a preparation method thereof, and in particular to a CaMnO3-PSAE composite material and a preparation method thereof, belonging to the field of material preparation. Background Art

[0002] Calcium manganate (CaMnO3) ceramics, as a typical perovskite material, exhibits diverse physical properties due to its structural diversity, such as excellent magnetic, electrical and thermoelectric properties. Not only that, it is also a potential excellent absorbing material with dielectric loss as the loss mechanism.

[0003] Silicon-containing arylacetylene resin (polysilylaryl-enyne, PSAE) is a polymer structure generated by m-diethynylbenzene and dichlorodimethylsilane under the catalysis of zinc powder. It can be cured at high temperature to form a high-temperature resistant cross-linked network structure containing benzene rings.

[0004] In the classification of absorbing materials, except for dielectric loss absorbing materials, the rest can be roughly divided into resistance loss type and magnetic loss type. Resistance loss type absorbing materials are mostly carbon materials, with poor impedance matching and poor absorption ability at high frequencies. Magnetic loss type absorbing materials have high density, poor high temperature performance and oxidation resistance. In most studies of absorbing composite materials based on polymers, the matrix is ​​usually high molecular polymers such as epoxy resin and polypyrrole. Although these matrices have good processability and wave transmission performance, their temperature resistance is poor. Summary of the invention

[0005] In view of the above problems, the present invention provides a high temperature resistant wave absorbing composite material and a preparation method thereof.

[0006] On the one hand, the present invention provides a high temperature resistant wave absorbing composite material, comprising: a resin matrix, and calcium manganate ceramic powder dispersed in the resin matrix; the resin matrix is ​​polysilicon aryl acetylene resin PSAE or paraffin. Among them, the present invention selects a large number of interfaces between the specific resin matrix and the calcium manganate ceramic powder, and the polarization effect between the interfaces will improve the wave absorbing performance.

[0007] Preferably, when the resin matrix is ​​paraffin, the content of the calcium manganate ceramic powder is 10 vol% to 60 vol%, preferably 50 vol% to 60 vol%; When the resin matrix is ​​polysilicon aryl acetylene resin PSAE, the content of the calcium manganate ceramic powder is 10 vol% to 50 vol%, preferably 30 vol% to 40 vol%.

[0008] Preferably, the particle size of the calcium manganate ceramic powder is 15 μm to 40 μm, preferably 15 μm to 25 μm; preferably, when the resin matrix is ​​polysilicon aromatic resin PSAE and the particle size of the calcium manganate ceramic powder is 5 μm to 10 μm, the content of the calcium manganate ceramic powder is 10 vol% to 35 vol%.

[0009] Preferably, when the resin matrix is ​​polysilicon aryl acetylene resin PSAE, the effective absorption bandwidth of the high temperature resistant wave absorbing composite material at a test frequency of 2 to 18 GHz is 2.26 GHz to 5.10 GHz, and the maximum reflection loss is -16.76 dB to -48.93 dB.

[0010] Preferably, when the resin matrix is ​​paraffin, the effective absorption bandwidth of the high temperature-resistant wave-absorbing composite material at a test frequency of 2 to 18 GHz is 0 GHz to 2.94 GHz, and the maximum reflection loss is -2.23 dB to -14.83 dB.

[0011] In another aspect, the present invention provides a method for preparing a high temperature resistant wave absorbing composite material, comprising: (1) heating the resin substrate in an oven until it is in a fluidized state, and then adding calcium manganate ceramic powder and mixing to obtain a mixture; (2) The obtained mixture is pre-polymerized and poured into a mold, then solidified, and finally cooled and demolded to obtain the high temperature resistant wave absorbing composite material.

[0012] The reaction mechanism of the present invention is as follows: during the prepolymerization process, the viscosity of the PSAE resin gradually increases, and the CaMnO3 ceramic powder is evenly dispersed in the resin without settling and agglomerating. During the mixing process, the slurry is heated under negative pressure conditions for vacuum bubbling treatment, and the resin matrix can fully enter the gaps formed by the ceramics stacked on each other to form a dense structure.

[0013] Preferably, in step (1), the heating temperature is 80-120° C.; the mixing method is mechanical stirring; the speed of the mechanical stirring is 60-120 rpm, and the time is 1-3 hours.

[0014] Preferably, in step (2), the prepolymerization temperature is 100-120° C. and the time is 2-3 hours.

[0015] Preferably, in step (2), vacuum bubbling is performed before curing; the parameters of the vacuum bubbling include: a bubbling temperature of 100 to 120° C., a bubbling time of 1 to 2 hours, and a vacuum degree of ≤100 Pa.

[0016] Preferably, in step (2), the curing temperature is 110 to 220° C., and the total curing time is 10 to 16 hours.

[0017] Furthermore, preferably, the curing method is staged curing; the parameters of the staged curing include: the number of stages n≥2, and the curing temperature T n >T n-1 The curing time of each stage is 3 to 5 hours and the total curing time is 10 to 16 hours; preferably, 25°C ≤ T n -T n-1 ≤35℃.

[0018] Beneficial effects of the present invention: 1. The CaMnO3-PSAE absorbing composite material prepared by the method of the present invention has improved absorbing performance compared with CaMnO3 ceramic powder and has certain temperature resistance; 2. The CaMnO3-PSAE wave absorbing composite material prepared by the method of the present invention has CaMnO3 ceramic powder dispersed evenly without agglomeration; 3. The method of the present invention has simple equipment, low investment, good processing performance, and can mass produce CaMnO3 and PSAE matrix. DETAILED DESCRIPTION

[0019] The present invention is further described below by the following embodiments. It should be understood that the following embodiments are only used to illustrate the present invention, but not to limit the present invention.

[0020] In the present disclosure, a high temperature resistant wave absorbing composite material comprises: a resin matrix, and calcium manganate ceramic powder dispersed in the resin matrix; the resin matrix is ​​polysilicon aryl acetylene resin PSAE or paraffin.

[0021] In an optional embodiment, the content of the calcium manganate ceramic powder may be 10 vol% to 50 vol%. The particle size of the calcium manganate ceramic powder may be 15 μm to 25 μm.

[0022] The following is an exemplary description of the preparation method of the solution cast CaMnO3-PSAE composite material.

[0023] Calcium manganate ceramic powder is prepared by high-energy ball milling. According to the chemical formula, CaCO3 and MnO2 with a purity greater than 99.9% are accurately weighed, added to a nylon jar pre-added with zirconium oxide balls, and deionized water is poured in, with a weight ratio of material: ball: water = 1:2:1.5; after ball milling, put it into an oven and dry it at 110°C for 8 hours. The dried powder is placed in a corundum sagger, calcined at 1100°C for 4 hours, and cooled with the furnace to obtain CaMnO3 synthetic powder.

[0024] The CaMnO3 synthetic material was sintered at 1350℃ for 4h. After crushing, a ceramic powder with a particle size of 15μm to 25μm was obtained. The ceramic powder was added into paraffin wax to test the microwave absorption performance of the ceramic powder.

[0025] The PSAE resin is heated in an oven until it becomes fluidized, and then the ceramic powder is added to the resin and mechanically stirred to mix uniformly to obtain a mixture.

[0026] The uniformly dispersed mixture is placed in an oven at 110°C for prepolymerization. The prepolymerization time may be 2-3 hours.

[0027] The purpose of prepolymerization in the preparation method of the present invention is to increase the viscosity of the resin so that the ceramic powder can be evenly dispersed in the resin matrix, and at the same time, it can prevent the material from generating microcracks due to uneven internal thermal expansion. Without prepolymerization, the ceramic powder will settle in the resin matrix. If the prepolymerization temperature is too high, the resin will react too quickly during the prepolymerization process and implode, which may damage the material at the least and cause a fire at the worst.

[0028] The mixture is poured into a mold by bulk casting technology and placed in a vacuum oven at 100-120°C for bubbling for 1-2 hours.

[0029] The mixture after bubbling is put into a vacuum sintering furnace for curing, and the mold is cooled and demoulded to obtain a product. The curing temperature system preferably includes: 110℃ / 8h+140℃ / 4h+170℃ / 4h+205℃ / 4h.

[0030] In the present invention, the effective absorption bandwidth of the high temperature-resistant wave-absorbing composite material under the test frequency of 2 to 18 GHz is 2.26 GHz to 5.10 GHz by using the coaxial line transmission / reflection method or instrument test.

[0031] In the present invention, the maximum reflection loss of the high temperature-resistant wave-absorbing composite material at a test frequency of 2 to 18 GHz is -16.76 dB to -48.93 dB when tested by a coaxial line transmission / reflection method or an instrument.

[0032] In the present invention, the heat resistance or weather resistance of the high temperature resistant wave absorbing composite material is tested by thermogravimetric analysis or an instrument.

[0033] The following further examples are given to illustrate the present invention in detail. It should also be understood that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention belong to the scope of protection of the present invention. The specific process parameters and the like in the following examples are also only examples within a suitable range, that is, those skilled in the art can make a selection within a suitable range through the description herein, and are not limited to the specific values ​​​​exemplified below.

[0034] Example 1 A high temperature resistant CaMnO3-PSAE wave absorbing composite material and a preparation method thereof are carried out according to the following steps: Step (1): Accurately weigh CaCO3 and MnO2 with a purity greater than 99.9% according to the chemical formula, add them into a nylon jar pre-added with zirconium oxide balls, and pour in deionized water, the weight ratio of which is material: ball: water = 1:2:1.5; after ball milling evenly, put it into an oven and dry it at 110°C for 8 hours. Put the dried powder into a corundum sagger, calcine it at 1100°C for 4 hours, and cool it with the furnace to obtain CaMnO3 synthetic powder; Step (2): sinter the CaMnO3 synthetic material at 1350°C for 4 hours. After crushing, a ceramic powder with a particle size of 15 μm to 25 μm is obtained. The ceramic powder is added to paraffin wax, wherein the volume ratio is ceramic powder: paraffin wax = 1:9, and the microwave absorption performance of the ceramic powder is tested, as shown in Table 1; Step (3): heat the polysilicon aryl acetylene resin PSAE in an oven (90° C.) until it is in a fluidized state, then add the ceramic powder into the resin in a volume ratio of ceramic powder: resin = 1:9, and mechanically stir and mix evenly; Step (4): Place the uniformly dispersed mixture in a 110°C oven for prepolymerization for 4 hours. Pour the mixture into a mold using a bulk casting technique and place it in a 100-120°C vacuum oven for bubbling for 1-2 hours; Step (5): Place the mixture after bubbling in a vacuum sintering furnace for curing at a temperature of 110°C / 8h+140°C / 4h+170°C / 4h+205°C / 4h, and wait for the mold to cool and demould to obtain a product. The composite absorbing material is obtained, and its properties are shown in Table 2.

[0035] Example 2 A high temperature resistant CaMnO3-PSAE wave absorbing composite material and a preparation method thereof are carried out according to the following steps: Step (1): Accurately weigh CaCO3 and MnO2 with a purity greater than 99.9% according to the chemical formula, add them into a nylon jar pre-added with zirconium oxide balls, and pour in deionized water, the weight ratio of which is material: ball: water = 1:2:1.5; after ball milling evenly, put it into an oven and dry it at 110°C for 8 hours. Put the dried powder into a corundum sagger, calcine it at 1100°C for 4 hours, and cool it with the furnace to obtain CaMnO3 synthetic powder; Step (2): sinter the CaMnO3 synthetic material at 1350°C for 4 hours. After crushing, a ceramic powder with a particle size of 15 μm to 25 μm is obtained. The ceramic powder is added to paraffin wax, wherein the volume ratio is ceramic powder: paraffin wax = 2:8, and the microwave absorption performance of the ceramic powder is tested, as shown in Table 1; Step (3): heat the polysilicon aryl acetylene resin PSAE in an oven (90° C.) until it is in a fluidized state, then add the ceramic powder into the resin in a volume ratio of ceramic powder: resin = 2:8, and mix them evenly with mechanical stirring; Step (4): Place the uniformly dispersed mixture in a 110°C oven for prepolymerization for 4 hours. Pour the mixture into a mold using a bulk casting technique and place it in a 100-120°C vacuum oven for bubbling for 1-2 hours; Step (5): Place the mixture after bubbling in a vacuum sintering furnace for curing at a temperature of 110°C / 8h+140°C / 4h+170°C / 4h+205°C / 4h, and wait for the mold to cool and demould to obtain a product. The composite absorbing material is obtained, and its properties are shown in Table 2.

[0036] Example 3 A high temperature resistant CaMnO3-PSAE wave absorbing composite material and a preparation method thereof are carried out according to the following steps: Step (1): Accurately weigh CaCO3 and MnO2 with a purity greater than 99.9% according to the chemical formula, add them into a nylon jar pre-added with zirconium oxide balls, and pour in deionized water, the weight ratio of which is material: ball: water = 1:2:1.5; after ball milling evenly, put it into an oven and dry it at 110°C for 8 hours. Put the dried powder into a corundum sagger, calcine it at 1100°C for 4 hours, and cool it with the furnace to obtain CaMnO3 synthetic powder; Step (2): sinter the CaMnO3 synthetic material at 1350°C for 4 hours. After crushing, a ceramic powder with a particle size of 15 μm to 25 μm is obtained. The ceramic powder is added to paraffin wax, wherein the volume ratio is ceramic powder: paraffin wax = 3:7, and the microwave absorption performance of the ceramic powder is tested, as shown in Table 1; Step (3): heat the polysilicon aryl acetylene resin PSAE in an oven (90° C.) until it is in a fluidized state, then add the ceramic powder into the resin in a volume ratio of ceramic powder: resin = 3:7, and mix them evenly with mechanical stirring; Step (4): Place the uniformly dispersed mixture in a 110°C oven for prepolymerization for 4 hours. Pour the mixture into a mold using a bulk casting technique and place it in a 100-120°C vacuum oven for bubbling for 1-2 hours; Step (5): Place the mixture after bubbling in a vacuum sintering furnace for curing at a temperature of 110°C / 8h+140°C / 4h+170°C / 4h+205°C / 4h, and wait for the mold to cool and demould to obtain a product. The composite absorbing material is obtained, and its properties are shown in Table 2.

[0037] Example 4 A high temperature resistant CaMnO3-PSAE wave absorbing composite material and a preparation method thereof are carried out according to the following steps: Step (1): Accurately weigh CaCO3 and MnO2 with a purity greater than 99.9% according to the chemical formula, add them into a nylon jar pre-added with zirconium oxide balls, and pour in deionized water, the weight ratio of which is material: ball: water = 1:2:1.5; after ball milling evenly, put it into an oven and dry it at 110°C for 8 hours. Put the dried powder into a corundum sagger, calcine it at 1100°C for 4 hours, and cool it with the furnace to obtain CaMnO3 synthetic powder; Step (2): sinter the CaMnO3 synthetic material at 1350°C for 4 hours. After crushing, a ceramic powder with a particle size of 15 μm to 25 μm is obtained. The ceramic powder is added to paraffin wax, wherein the volume ratio is ceramic powder: paraffin wax = 4:6, and the microwave absorption performance of the ceramic powder is tested, as shown in Table 1; Step (3): Heat the polysilicon aryl acetylene resin PSAE in an oven (90° C.) until it is in a fluidized state, then add the ceramic powder into the resin in a volume ratio of ceramic powder:resin = 4:6, and mix them evenly with mechanical stirring; Step (4): Place the uniformly dispersed mixture in a 110°C oven for prepolymerization for 4 hours. Pour the mixture into a mold using a bulk casting technique and place it in a 100-120°C vacuum oven for bubbling for 1-2 hours; Step (5): Place the mixture after bubbling in a vacuum sintering furnace for curing at a temperature of 110°C / 8h+140°C / 4h+170°C / 4h+205°C / 4h, and wait for the mold to cool and demould to obtain a product. The composite absorbing material is obtained, and its properties are shown in Table 2.

[0038] Example 5 A high temperature resistant CaMnO3-PSAE wave absorbing composite material and a preparation method thereof are carried out according to the following steps: Step (1): Accurately weigh CaCO3 and MnO2 with a purity greater than 99.9% according to the chemical formula, add them into a nylon jar pre-added with zirconium oxide balls, and pour in deionized water, the weight ratio of which is material: ball: water = 1:2:1.5; after ball milling evenly, put it into an oven and dry it at 110°C for 8 hours. Put the dried powder into a corundum sagger, calcine it at 1100°C for 4 hours, and cool it with the furnace to obtain CaMnO3 synthetic powder; Step (2): sinter the CaMnO3 synthetic material at 1350°C for 4 hours. After crushing, a ceramic powder with a particle size of 15 μm to 25 μm is obtained. The ceramic powder is added to paraffin wax, wherein the volume ratio is ceramic powder: paraffin wax = 5:5, and the microwave absorption performance of the ceramic powder is tested, as shown in Table 1; Step (3): heat the polysilicon aryl acetylene resin PSAE in an oven (90° C.) until it is in a fluidized state, then add the ceramic powder into the resin in a volume ratio of ceramic powder: resin = 5:5, and mix them evenly with mechanical stirring; Step (4): Place the uniformly dispersed mixture in a 110°C oven for prepolymerization for 4 hours. Pour the mixture into a mold using a bulk casting technique and place it in a 100-120°C vacuum oven for bubbling for 1-2 hours; Step (5): Place the mixture after bubbling in a vacuum sintering furnace for curing at a temperature of 110°C / 8h+140°C / 4h+170°C / 4h+205°C / 4h, and wait for the mold to cool and demould to obtain a product. The composite absorbing material is obtained, and its properties are shown in Table 2.

[0039] Example 6 The preparation method of the high temperature resistant CaMnO3-PSAE absorbent composite material in Example 6 is the same as that in Example 5, with the only difference being that in step (4), the uniformly dispersed mixture is placed in an oven at 105°C for prepolymerization for 4 hours.

[0040] Example 7 The preparation method of the high temperature resistant CaMnO3-PSAE absorbent composite material in Example 7 is similar to that in Example 4, with the only difference being that in step (4), the uniformly dispersed mixture is placed in an oven at 115°C for prepolymerization for 4 hours.

[0041] Example 8 The preparation method of the high temperature resistant CaMnO3-PSAE wave absorbing composite material in Example 8 is the same as that in Example 4, except that in step (3), the CaMnO3 synthetic material is sintered at 1350° C. for 4 h and crushed to obtain a ceramic powder with a particle size of 5 μm to 10 μm.

[0042] Example 9 The preparation method of the high temperature resistant CaMnO3-PSAE wave absorbing composite material in this embodiment 9 is the same as that in embodiment 4, except that in step (3), the CaMnO3 synthetic material is sintered at 1350°C for 4 hours and crushed to obtain a ceramic powder with a particle size of 30 μm to 40 μm.

[0043] Example 10 The preparation method of the high temperature resistant CaMnO3-PSAE absorbent composite material in Example 10 is the same as that in Example 4, except that in step (4), the uniformly dispersed mixture is placed in an oven at 110° C. for prepolymerization for 4 hours. The mixture is poured into a mold by bulk casting technology without vacuum degassing.

[0044] Embodiment 11 The preparation method of the high temperature resistant CaMnO3-PSAE wave absorbing composite material in this embodiment 11 is the same as that in embodiment 8, except that in step (3), the CaMnO3 synthetic material is sintered at 1350°C for 4 hours. The ceramic powder with a particle size of 5 μm to 10 μm is obtained by crushing; and the ratio of CaMnO3 ceramic powder to resin is controlled to be 3.5:6.5.

[0045] Comparative Example 1 The preparation method of the high temperature resistant CaMnO3-PSAE absorbing composite material in this comparative example 1 is similar to that in example 4, with the only difference being that in step (4), the uniformly dispersed mixture is placed in an oven at 95°C for prepolymerization for 4 hours.

[0046] Comparative Example 2 The preparation method of the high temperature resistant CaMnO3-PSAE absorbing composite material in Comparative Example 2 is the same as that in Example 4, with the only difference being that in step (4), the uniformly dispersed mixture is placed in an oven at 125°C for prepolymerization for 4 hours.

[0047] Comparative Example 3 The preparation method of the high temperature resistant CaMnO3-PSAE absorbent composite material in this comparative example 3 refers to that in example 4, with the only difference being that in step (3), the polysilicon aryl acetylene resin PSAE is heated in an oven until it becomes fluidized, and then the ceramic powder is added to the resin, wherein the volume ratio of ceramic powder:resin = 6:4.

[0048] Table 1 shows the performance parameters of the composite absorbing material prepared by the present invention:

[0049] Table 2 shows the performance parameters of the composite absorbing material prepared by the present invention: Sample No. Resin CMO addition amount Effective absorption bandwidth Maximum reflection loss Test frequency Example 1 Polysilicon Aromatic Resin 10vol% 2.26 16.76 2-18GHz Example 2 Polysilicon Aromatic Resin 20vol% 3.64 28.01 2-18GHz Example 3 Polysilicon Aromatic Resin 30vol% 4.24 37.53 2-18GHz Example 4 Polysilicon Aromatic Resin 40vol% 5.10 41.66 2-18GHz Example 5 Polysilicon Aromatic Resin 50vol% 4.16 48.93 2-18GHz Example 6 Polysilicon Aromatic Resin 40vol% 4.78 40.51 2-18GHz Example 7 Polysilicon Aromatic Resin 40vol% 4.56 38.69 2-18GHz Example 8 Polysilicon Aromatic Resin 40vol% Cannot be prepared - 2-18GHz Example 9 Polysilicon Aromatic Resin 40vol% 3.96 36.64 2-18GHz Example 10 Polysilicon Aromatic Resin 40vol% 4.06 42.11 2-18GHz Embodiment 11 Polysilicon Aromatic Resin 35vol% 4.42 38.92 2-18GHz Comparative Example 1 Polysilicon Aromatic Resin 40vol% 3.65 35.26 2-18GHz Comparative Example 2 Polysilicon Aromatic Resin 40vol% Product Explosion - 2-18GHz Comparative Example 3 Polysilicon Aromatic Resin 60vol% Cannot be prepared - 2-18GHz .

[0050] In Example 8 of the present invention, since the ceramic powder has a relatively low particle size and a relatively large surface energy, the maximum doping ratio when mixed with the silicon-containing aromatic acetylene resin can only reach 35 vol%. If the doping ratio is increased further, the slurry viscosity will be too high to be stirred, and a finished product doped with 40 vol% ceramic powder cannot be prepared. In Comparative Example 2 of the present invention, since the polymer curing reaction speed is too fast when the prepolymerization temperature is 125° C., an implosion phenomenon (polymerization is too violent and explosion occurs) will occur, and a finished product cannot be prepared; In comparative example 3 of the present invention, since the resin itself has a certain viscosity, the viscosity of the ceramic-resin slurry will further increase with the increase of ceramic powder, and the maximum doping ratio can only reach 50 vol%. If the doping ratio is further increased, the slurry viscosity will be too high and it will be impossible to stir, and a uniformly dispersed composite material cannot be prepared.

Claims

1. A high temperature resistant wave absorbing composite material, characterized in that: include: A resin matrix and calcium manganate ceramic powder dispersed in the resin matrix; the resin matrix is ​​polysilicon aryl acetylene resin PSAE or paraffin.

2. The high temperature resistant wave absorbing composite material according to claim 1, characterized in that: When the resin matrix is ​​paraffin, the content of the calcium manganate ceramic powder is 10 vol% to 60 vol%, preferably 50 vol% to 60 vol%; When the resin matrix is ​​polysilicon aryl acetylene resin PSAE, the content of the calcium manganate ceramic powder is 10 vol% to 50 vol%, preferably 30 vol% to 40 vol%.

3. The high temperature resistant wave absorbing composite material according to claim 1, characterized in that: The particle size of the calcium manganate ceramic powder is 15 μm to 40 μm, preferably 15 μm to 25 μm; Preferably, when the resin matrix is ​​polysilicon aryl acetylene resin PSAE and the particle size of the calcium manganate ceramic powder is 5 μm to 10 μm, the content of the calcium manganate ceramic powder is 10 vol% to 35 vol%.

4. The high temperature resistant wave absorbing composite material according to any one of claims 1 to 4, characterized in that: When the resin matrix is ​​polysilicon aromatic acetylene resin PSAE, the effective absorption bandwidth of the high temperature resistant wave absorbing composite material at a test frequency of 2 to 18 GHz is 2.26 GHz to 5.10 GHz, and the maximum reflection loss is -16.76 dB to -48.93 dB; Alternatively, when the resin matrix is ​​paraffin, the effective absorption bandwidth of the high temperature-resistant wave-absorbing composite material at a test frequency of 2 to 18 GHz is 0 GHz to 2.94 GHz, and the maximum reflection loss is -2.23 dB to -14.83 dB.

5. A method for preparing the high temperature resistant wave absorbing composite material according to any one of claims 1 to 4, characterized in that: include: (1) heating the resin substrate in an oven until it is in a fluid state, and then adding calcium manganate ceramic powder and mixing to obtain a mixture; (2) pre-polymerizing the obtained mixture and pouring it into a mold, and then curing it, and finally cooling and demolding it to obtain the high temperature resistant wave absorbing composite material.

6. The preparation method according to claim 5, characterized in that: In step (1), the heating temperature is 80-120° C.; the mixing method is mechanical stirring; the speed of the mechanical stirring is 60-120 rpm, and the time is 1-3 hours.

7. The preparation method according to claim 5, characterized in that: In step (2), the prepolymerization temperature is 100 to 120° C. and the time is 2 to 3 hours.

8. The preparation method according to claim 5, characterized in that: In step (2), vacuum bubbling is performed before curing; the parameters of the vacuum bubbling include: a bubbling temperature of 100 to 120° C., a bubbling time of 1 to 2 hours, and a vacuum degree of ≤100 Pa.

9. The preparation method according to any one of claims 5 to 8, characterized in that: In step (2), the curing temperature is 110 to 220° C., and the total curing time is 10 to 16 hours.

10. The preparation method according to claim 9, characterized in that: The curing method is staged curing; the parameters of the staged curing include: the number of stages n≥2, and the curing temperature T n >T n-1 The curing time of each stage is 3 to 5 hours and the total curing time is 10 to 16 hours; preferably, 25°C ≤ T n -T n-1 ≤35℃.

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