A multilayer structure silicon carbide wave-absorbing material and a preparation method thereof

Abstract

The application provides a multilayer structure silicon carbide wave-absorbing material and a preparation method thereof. The multilayer structure silicon carbide wave-absorbing material comprises a first plane layer, a first circular tube layer, a second plane layer, a second circular tube layer and a third plane layer which are sequentially stacked, the first circular tube layer and the second circular tube layer comprise a plurality of hollow circular tubes which are arranged in parallel, adjacent hollow circular tubes abut against each other, and the multilayer structure silicon carbide wave-absorbing material comprises the following raw materials in percentage by mass: 40-80% of silicon carbide powder, 10-40% of paraffin, 5-10% of thermoplastic resin, 1-5% of stearic acid and 1-5% of sintering aid. The application improves the raw material composition and structure of the silicon carbide material, can broaden the wave-absorbing frequency band and improve the mechanical properties of the material by adjusting the thermoplastic resin, and the material has a multilayer structure, two layers of hollow circular tubes are arranged at intervals, and the wave-absorbing performance of the material can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wave-absorbing material preparation, in particular to a silicon carbide wave-absorbing material and a preparation method thereof. BACKGROUND

[0002] With the rapid development of aerospace vehicles, higher requirements are put forward for the protective materials and structures on the surface of the vehicles, therefore, it is urgent to develop materials integrated with light weight, load bearing, wide frequency and high-efficiency wave-absorbing functions. Silicon carbide ceramic material is a typical covalent compound, which has the advantages of low density, high thermal conductivity, small thermal expansion coefficient, good chemical stability and high mechanical strength, and is a high-potential high-temperature and corrosion-resistant material, but the electrical conductivity and dielectric loss of silicon carbide material are low, which is not conducive to electromagnetic wave absorption.

[0003] In recent years, a number of studies have shown that different levels of structure have a superposition effect on wave-absorbing ability, which can effectively improve the wave-absorbing performance of the material, so theoretically the wave-absorbing performance of silicon carbide material can be improved by compounding or structure design.

[0004] However, silicon carbide is a compound with extremely strong covalent bond, which has the characteristics of high hardness, insulation and high temperature resistance, so it cannot be processed by traditional methods such as pressure processing, cutting processing and wire electrical discharge machining. At present, the only processing method that can be used is diamond grinding wheel, but this method has high grinding processing cost and long cycle, so it is very difficult to prepare large-size and complex-shaped structure silicon carbide ceramic parts, which cannot effectively control the spatial structure of silicon carbide material and limits the development of silicon carbide wave-absorbing material. SUMMARY

[0005] In view of the deficiencies of the prior art, the technical problem to be solved by the present application is how to control the spatial structure of silicon carbide material and improve its wave-absorbing performance.

[0006] To solve the above problems, the present application provides a multi-layer structure silicon carbide wave-absorbing material, which comprises a first plane layer, a first circular tube layer, a second plane layer, a second circular tube layer and a third plane layer arranged in sequence, the first circular tube layer and the second circular tube layer comprise a plurality of parallel arranged hollow circular tubes, adjacent hollow circular tubes abut, and the multi-layer structure silicon carbide wave-absorbing material comprises the following raw materials in mass percentage: silicon carbide powder 40-80%, paraffin 10-40%, thermoplastic resin 5-10%, stearic acid 1-5% and sintering aid 1-5%.

[0007] The application improves the raw material and structure of the silicon carbide material, and the mechanical properties of the material can be improved by adjusting the content of the organic matter; the material has a multi-layer structure, two layers of hollow circular pipes are arranged at intervals, the wave propagation process can continuously reflect and refract in different directions, thereby reducing the wave propagation energy and improving the wave absorption performance of the material.

[0008] Further, the thickness of the first planar layer is 0.5-1 mm, the thickness of the first circular pipe layer is 0.5-1 mm, the thickness of the second planar layer is 0.5-1 mm, the thickness of the second circular pipe layer is 0.5-1 mm, and the thickness of the third planar layer is 0.5-1 mm. By controlling the thickness of each layer in the composite material, the mechanical properties and wave absorption performance of the material can be adjusted.

[0009] Further, the outer diameter of the hollow circular pipe is 0.5-1 mm, and the wall thickness is 0.1-0.2 mm.

[0010] Further, the thermoplastic resin is selected from any one or more of polylactic acid, ABS, polycarbonate, nylon, polyethylene, ethylene vinyl acetate polymer, etc. Selecting a high polymer with good bonding properties is beneficial to the molding of the wire.

[0011] Further, the sintering aid is selected from any one or more of aluminum, silicon, aluminum oxide, yttrium oxide, carbon black.

[0012] Further, the particle size of the silicon carbide powder and the sintering aid is 200-400 mesh, and the particle size of the thermoplastic resin is greater than 100 mesh.

[0013] The application also provides a preparation method of the above-mentioned multi-layer structure silicon carbide wave absorption material, comprising the following steps:

[0014] S1, mixing and granulation: the silicon carbide powder, sintering aid and stearic acid are uniformly mixed in a ball mill, dried, and then uniformly mixed with the thermoplastic resin and paraffin in a internal mixer, crushed to obtain mixed particles with a particle size of 50-500 μm;

[0015] S2, extruding into a wire: the dried mixed particles are added to a melt extrusion molding machine, the powder is transported forward under the action of the screw, and is melt mixed and extruded to obtain a silicon carbide / thermoplastic resin composite wire;

[0016] S3, printing molding: the silicon carbide / thermoplastic resin composite wire is placed into a 3D printing device, the device parameters are adjusted, and the printing is performed under the control of a computer to perform layer-by-layer solidification and printing of the green body in a layer-by-layer stacking manner;

[0017] S4, debinding: the printed green body is debound to obtain a preform;

[0018] S5, sintering: placing the preform in a sintering furnace, high-temperature sintering to obtain a multi-layer structure silicon carbide wave-absorbing material.

[0019] The preparation method of the application adopts a fused deposition 3D printing forming process, the ceramic raw material is pretreated through a mixing and granulating step, a silicon carbide / thermoplastic resin composite wire that can be compatible with ordinary 3D printing equipment is obtained, a multi-layer structure silicon carbide with a hollow circular tube is successfully prepared, the design and rapid manufacturing of a complex structure are realized, special high-temperature fused 3D printing equipment is not needed, the production efficiency is improved, and the cost is saved.

[0020] Further, in the step S1, the ball milling speed is 200-400 r / min, the drying temperature is 50-80 DEG C, the density mixing temperature is 120-180 DEG C, and the rotating speed is 15-40 r / min.

[0021] Further, in the step S2, the screw rotating speed of the melt extrusion forming machine is 10-20 r / min, the preheating zone temperature is 120-140 DEG C, and the melt mixing temperature is 140-150 DEG C, and the step S1 mixing and extrusion forming can obtain a millimeter level diameter silicon carbide / thermoplastic resin composite wire.

[0022] Further, in the step S3, the nozzle temperature of the 3D printing equipment is controlled at 100-200 DEG C, the object table temperature is controlled at 20-150 DEG C, the printing speed is 10-50 mm / s, and the single layer thickness is 0.1-0.2 mm, and the step S3 is obtained in a layered solidification, layer-by-layer superposition manner to obtain a ceramic / polymer green body.

[0023] Further, the step S4 is specifically as follows: the green body is heated to 150-250 DEG C at a heating rate of 1-5 DEG C / min in a debinding furnace, and then heated to 500-700 DEG C at a heating rate of 0.2-1 DEG C / min, and kept for 1-2 h to obtain a preform. The distributed heating mode can improve the production efficiency, slow down the second stage heating speed, and avoid cracking of the green body during debinding.

[0024] Further, the step S5 is specifically as follows: the preform is placed in a sintering furnace, heated to 1900-2200 DEG C at a heating rate of 2-5 DEG C / min, and kept for 1-3 h to obtain a multi-layer structure silicon carbide wave-absorbing material. Through debinding and sintering, a high-precision silicon carbide wave-absorbing material with excellent performance is obtained. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The structure of the multi-layer structure silicon carbide wave-absorbing material of the embodiment of the application is shown in the figure;

[0026] Figure 2This is a side view of the multilayer silicon carbide microwave absorbing material according to a specific embodiment of the present invention.

[0027] Figure 3 The image shows a scanning electron microscope (SEM) image of the silicon carbide absorbing material obtained in specific embodiment 1 of the present invention.

[0028] Figure 4 The image shows a scanning electron microscope (SEM) image of the silicon carbide absorbing material obtained in specific embodiment 1 of the present invention.

[0029] Figure 5 The image shows the absorption curve of the silicon carbide absorbing material obtained in specific embodiment 1 of the present invention.

[0030] Explanation of reference numerals in the attached figures:

[0031] 1-First planar layer, 2-First circular tube layer, 3-Second planar layer, 4-Second circular tube layer, 5-Third planar layer. Detailed Implementation

[0032] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that the following embodiments are only used to illustrate the implementation methods and typical parameters of the present invention, and are not intended to limit the parameter range described in the present invention. Reasonable variations derived therefrom are still within the protection scope of the claims of the present invention.

[0033] It should be noted that the endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0034] Combination Figure 1 and Figure 2 As shown, an embodiment of the present invention provides a multilayer silicon carbide absorbing material, comprising a first planar layer 1, a first circular tube layer 2, a second planar layer 3, a second circular tube layer 4, and a third planar layer 5 stacked sequentially. The first circular tube layer 2 and the second circular tube layer 4 each comprise multiple parallel hollow circular tubes, with adjacent hollow circular tubes abutting each other. This material has a multilayer structure, with two layers of hollow circular tubes spaced apart, which can reduce the mass of the material and improve its microwave absorption performance.

[0035] The thickness of the first planar layer 1 is 0.5-1 mm, the thickness of the first circular tube layer 2 is 0.5-1 mm, the thickness of the second planar layer 3 is 0.5-1 mm, the thickness of the second circular tube layer 4 is 0.5-1 mm, and the thickness of the third planar layer 5 is 0.5-1 mm. The thickness of each planar layer and circular tube layer can be the same or different. Preferably, the outer diameter of the hollow circular tube in the circular tube layer is 0.5-1 mm, and the wall thickness is 0.1-0.2 mm.

[0036] The raw materials of the above-mentioned silicon carbide wave-absorbing material are mainly silicon carbide powder and thermoplastic resin, and the thermoplastic resin is selected from polylactic acid, ABS, polycarbonate, nylon, polyethylene, ethylene vinyl acetate polymer, etc. Preferably, the particle size of the silicon carbide powder is 200-400 mesh, and the particle size of the thermoplastic resin is greater than 100 mesh.

[0037] The silicon carbide wave-absorbing material is prepared by using a fused deposition 3D printing forming process, and the specific preparation method is as follows:

[0038] S1, mixing and granulation: 40%-80% of silicon carbide powder, 1%-5% of stearic acid, and 1%-5% of sintering aid are placed in a ball mill to mix uniformly, dried, and then mixed uniformly with 10%-40% of paraffin and 5%-10% of thermoplastic resin in a banbury mixer, crushed to obtain mixed particles with a particle size of 50-500 μm. In a specific embodiment, the mixing process is as follows: according to the ratio, the silicon carbide powder, stearic acid and sintering aid are placed in a ball mill to mix uniformly, dried, wherein the ball milling speed is 200-400 r / min, and the drying temperature is 50-80℃. Then put the thermoplastic resin and paraffin into the banbury mixer for mixing, the mixing temperature is 120-180℃, the rotating speed is 15-40 r / min, and the time is 1-5 h. After mixing, the particles with a particle size of 50-500 μm are obtained by jaw crusher.

[0039] S2, extruding into a wire: the dried mixed particles are added to a melt extrusion forming machine, the powder is transported forward under the action of the screw, and the silicon carbide / thermoplastic resin composite wire is obtained by melt mixing and extrusion forming. In a specific embodiment, the screw rotating speed of the melt extrusion forming machine is 10-20 r / min, the preheating zone temperature is 120-140℃, and the melt mixing temperature is 140-150℃. This step can obtain a millimeter-level diameter of silicon carbide / thermoplastic resin composite wire through mixing and extrusion forming.

[0040] S3, printing molding: the silicon carbide / thermoplastic resin composite wire is placed into a 3D printing device, the device parameters are adjusted, and printing is performed under computer control to print the green body in a layer-by-layer solidification and layer-by-layer stacking manner. In specific embodiments, the temperature of the nozzle of the 3D printing device is controlled at 100-200°C, the temperature of the object table is controlled at 20-150°C, the printing speed is 10-50 mm / s, and the single layer thickness is 0.1-0.2 mm.

[0041] S4, debinding: the printed green body is debound to obtain a preform. In specific embodiments, the green body is heated in a debinding furnace at a heating rate of 5-10°C / min to 150-250°C, and then heated at a heating rate of 0.2-1°C / min to 500-700°C, and held for 1-2 h to complete the debinding.

[0042] S5, sintering: the preform is placed in a sintering furnace to obtain a multi-layer structure silicon carbide wave-absorbing material by high-temperature sintering. In specific embodiments, the preform is heated in the sintering furnace at a heating rate of 2-5°C / min to 1900-2200°C, and held for 1-3 h to complete the sintering process.

[0043] The above preparation method of the fused deposition 3D printing molding process successfully prepared a multi-layer structure silicon carbide wave-absorbing material, the equipment used is simple, the production cycle is short, the constraints of mold forming are eliminated, the production efficiency is improved, the cost is saved, and the wave-absorbing material can be efficiently and batch-prepared.

[0044] The technical solutions and effects of the present application are described below through specific embodiments. The performance test methods used in the following embodiments are as follows: the material density test method refers to GB / T 25995-2010 Fine Ceramics Density and Apparent Porosity Test Method; the material bending strength test method refers to GB / T 6569-2006 Fine Ceramics Bending Strength Test Method.

[0045] Example 1

[0046] A multi-layer structure silicon carbide wave-absorbing material is designed, which includes a first planar layer, a first circular tube layer, a second planar layer, a second circular tube layer, and a third planar layer arranged in sequence, the first circular tube layer and the second circular tube layer include a plurality of parallel arranged hollow circular tubes, and adjacent hollow circular tubes abut. The thickness of the first planar layer is 1 mm, the thickness of the first circular tube layer is 1 mm, the thickness of the second planar layer is 1 mm, the thickness of the second circular tube layer is 1 mm, the thickness of the third planar layer is 1 mm, the outer diameter of the hollow circular tube in the circular tube layer is 1 mm, and the wall thickness is 0.1 mm.

[0047] The preparation process of the silicon carbide wave-absorbing material is as follows:

[0048] Mixing and granulation: 76% silicon carbide powder, 3% stearic acid, 2% carbon black were mixed uniformly in a ball mill, dried, and then put into an internal mixer with 16% paraffin, 3% thermoplastic resin. The mixing temperature was 160°C, the rotation speed was 25r / min, and the time was 3h. Then the mixed particles with a particle size of about 50-500μm were obtained.

[0049] Extrusion into wire: the dried mixed particles were added to a melt extrusion molding machine, the screw rotation speed was controlled at 20r / min, the preheating zone temperature was 130°C, and the melt mixing temperature was 160°C. The silicon carbide / thermoplastic resin composite wire with a diameter of 1.75±0.05mm was obtained by extrusion molding.

[0050] Printing molding: the silicon carbide / thermoplastic resin composite wire was put into a 3D printing device, the nozzle temperature was controlled at 180°C, the stage temperature was controlled at 50°C, the printing speed was 20mm / s, and the single layer thickness was 0.1mm. The green body was printed in a layer-by-layer solidification and layer-by-layer stacking manner.

[0051] S4, debinding: the printed green body was put into a debinding furnace, heated to 200°C at a heating rate of 5°C / min, and then heated to 600°C at a heating rate of 10°C / h, and kept for 1h to complete the debinding to obtain a preform.

[0052] S5, sintering: the preform was placed in a sintering furnace and heated to 2000°C at a heating rate of 5°C / min, and kept for 2h to obtain a designed structure of silicon carbide wave-absorbing material, as shown in Figure 3 and Figure 4 , the material is dense.

[0053] S6, wave-absorbing test: the prepared structure type silicon carbide wave-absorbing material was printed into wave-absorbing test samples under different wave bands by melt deposition, and the wave-absorbing performance in the X wave band 8.2-12.4GHz was tested.

[0054] The density of the silicon carbide wave-absorbing material was 3.15g / cm 3 ; the bending strength was 220MPa; and Figure 5 It can be seen that the multi-layer structure of the silicon carbide material has excellent wave-absorbing performance, and the minimum reflection loss in the X wave band is-19.8dB.

[0055] Example 2

[0056] A multi-layer structure silicon carbide wave-absorbing material is designed, which comprises a first planar layer, a first circular tube layer, a second planar layer, a second circular tube layer and a third planar layer arranged in sequence, the first circular tube layer and the second circular tube layer comprise a plurality of hollow circular tubes arranged in parallel, and adjacent hollow circular tubes abut each other. The thickness of the first planar layer is 0.5 mm, the thickness of the first circular tube layer is 1 mm, the thickness of the second planar layer is 1 mm, the thickness of the second circular tube layer is 1 mm, and the thickness of the third planar layer is 0.5 mm. The outer diameter of the hollow circular tube in the circular tube layer is 1 mm, and the wall thickness is 0.2 mm.

[0057] The preparation process of the silicon carbide wave-absorbing material is as follows:

[0058] Granulation: 60% silicon carbide powder, 5% stearic acid and 5% carbon black are uniformly mixed in a ball mill, dried, and then put into a banbury mixer with 25% paraffin and 5% thermoplastic resin. The mixing temperature is 180℃, the rotating speed is 20r / min, and the time is 2h. Then crush to obtain mixed particles with a particle size of about 50-500μm.

[0059] Mixing into wire: After drying, the mixed particles are added to a melt extrusion molding machine, the screw rotating speed is controlled at 10r / min, the preheating zone temperature is 120℃, and the melt mixing temperature is 140℃. Extrusion molding obtains a silicon carbide / thermoplastic resin composite wire with a diameter of 1.75±0.05mm.

[0060] Printing molding: The silicon carbide / thermoplastic resin composite wire is put into a 3D printing equipment, the nozzle temperature is controlled at 170℃, the object table temperature is controlled at 80℃, the printing speed is 30mm / s, and the single layer thickness is 0.2mm. Layered solidification, layer-by-layer stacking method is used to print the green body.

[0061] S4, debinding: The printed green body is put into a debinding furnace, heated to 250℃ at a heating rate of 10℃ / min, then heated to 700℃ at a heating rate of 10℃ / h, and kept for 1h to complete the debinding to obtain a preform.

[0062] S5, sintering: The preform is placed in a sintering furnace and heated to 1900℃ at a heating rate of 2℃ / min, and kept for 3h to obtain a silicon carbide wave-absorbing material with a designed structure.

[0063] The density of the silicon carbide material is 3.06g / cm 3 ; the bending strength is 183MPa, and the minimum reflection loss in X wave band is-18.4dB.

[0064] Example 3

[0065] A multi-layer structure silicon carbide wave-absorbing material is designed, which comprises a first planar layer, a first circular tube layer, a second planar layer, a second circular tube layer and a third planar layer arranged in sequence, the first circular tube layer and the second circular tube layer comprise a plurality of hollow circular tubes arranged in parallel, and adjacent hollow circular tubes abut each other. The thickness of the first planar layer is 1 mm, the thickness of the first circular tube layer is 0.8 mm, the thickness of the second planar layer is 0.6 mm, the thickness of the second circular tube layer is 0.8 mm, and the thickness of the third planar layer is 1 mm. The outer diameter of the hollow circular tube in the circular tube layer is 0.8 mm, and the wall thickness is 0.1 mm.

[0066] The preparation process of the silicon carbide wave-absorbing material is as follows:

[0067] Banbury granulation: 70% silicon carbide powder, 3% stearic acid, 5% aluminum oxide and yttrium oxide are mixed uniformly in a ball mill, dried, and then put into a banbury mixer with 17% paraffin and 5% thermoplastic resin. The banbury temperature is 185℃, the rotation speed is 15r / min, and the time is 3h. Then crush to obtain mixed particles with a particle size of about 50-500μm.

[0068] Extruded into wire: the dried mixed particles are added to a melt extrusion molding machine, the screw rotation speed is controlled at 15r / min, the preheating zone temperature is 120℃, and the melt mixing temperature is 150℃. Extrusion molding obtains a silicon carbide / thermoplastic resin composite wire with a diameter of 1.75±0.05mm.

[0069] Printed molding: the silicon carbide / thermoplastic resin composite wire is put into a 3D printing device, the nozzle temperature is controlled at 150℃, the object table temperature is controlled at 40℃, the printing speed is 80mm / s, and the single layer thickness is 0.1mm. Print the blank in a layered solidification and layer-by-layer stacking manner.

[0070] S4, debinding: the printed blank is put into a debinding furnace, heated to 200℃ at a heating rate of 5℃ / min, then heated to 600℃ at a heating rate of 10℃ / h, and kept for 2h to complete the debinding to obtain a preform.

[0071] S5, sintering: the preform is placed in a sintering furnace and heated to 2100℃ at a heating rate of 5℃ / min, and kept for 2h to obtain a silicon carbide wave-absorbing material with a designed structure.

[0072] The density of the silicon carbide material is 3.13g / cm 3 ; the bending strength is 204MPa, and the minimum reflection loss in the X wave band is-17.6dB.

[0073] Example 4

[0074] A multi-layer structure silicon carbide wave-absorbing material is designed, which comprises a first planar layer, a first circular tube layer, a second planar layer, a second circular tube layer and a third planar layer arranged in sequence, the first circular tube layer and the second circular tube layer comprise a plurality of hollow circular tubes arranged in parallel, and adjacent hollow circular tubes abut each other. The thickness of the first planar layer is 0.8 mm, the thickness of the first circular tube layer is 0.5 mm, the thickness of the second planar layer is 1 mm, the thickness of the second circular tube layer is 0.8 mm, and the thickness of the third planar layer is 1 mm. The outer diameter of the hollow circular tube in the circular tube layer is 0.5 mm, and the wall thickness is 0.1 mm.

[0075] The preparation process of the silicon carbide wave-absorbing material is as follows:

[0076] Banbury granulation: 67% silicon carbide powder, 1% stearic acid and 4% aluminum oxide are uniformly mixed in a ball mill, dried, and then put into a banbury mixer with 25% paraffin and 3% thermoplastic resin. The banbury temperature is 160℃, the rotation speed is 30r / min, and the time is 4h. Then crush to obtain mixed particles with a particle size of about 50-500μm.

[0077] Mixing into wire: the dried mixed particles are added to a melt extrusion molding machine, the screw rotation speed is controlled at 10r / min, the preheating zone temperature is 130℃, and the melt mixing temperature is 150℃. Extrusion molding obtains a silicon carbide / thermoplastic resin composite wire with a diameter of 1.75±0.05mm.

[0078] Printing molding: the silicon carbide / thermoplastic resin composite wire is put into a 3D printing equipment, the nozzle temperature is controlled at 170℃, the object table temperature is controlled at 60℃, the printing speed is 30mm / s, and the single layer thickness is 0.1mm. Print the blank in a layered solidification and layer-by-layer stacking manner.

[0079] S4, debinding: the printed blank is put into a debinding furnace, heated to 200℃ at a heating rate of 5℃ / min, then heated to 650℃ at a heating rate of 10℃ / h, and kept for 2h to complete the debinding to obtain a preform.

[0080] S5, sintering: the preform is placed in a sintering furnace and heated to 2200℃ at a heating rate of 5℃ / min, and kept for 1.5h to obtain a silicon carbide wave-absorbing material with a designed structure.

[0081] The density of the silicon carbide material is 3.09g / cm 3 ; the bending strength is 189MPa, and the minimum reflection loss in the X wave band is-19dB.

[0082] Comparative Example 1

[0083] A single-layer structure silicon carbide wave-absorbing material is prepared, with a thickness of 5mm; the preparation raw materials and process are the same as those of Example 1.

[0084] The density of the tested silicon carbide material is 3.16 g / cm 3 ; the minimum reflection loss thereof in the X waveband is -14 dB.

[0085] Comparative Example 2

[0086] A multi-layered structure of a silicon carbide wave-absorbing material is prepared, which comprises a first planar layer, a first circular tube layer and a second planar layer arranged in sequence. The thickness of the first planar layer is 1.5 mm, the thickness of the first circular tube layer is 1 mm, and the thickness of the second planar layer is 1.5 mm. The outer diameter of the hollow circular tube in the circular tube layer is 1 mm, and the wall thickness is 0.2 mm.

[0087] The raw materials and the process for preparing the same are the same as those of Example 2.

[0088] The density of the tested silicon carbide material is 3.15 g / cm 3 ; the minimum reflection loss thereof in the X waveband is -15.7 dB.

[0089] Although the present application has been disclosed with reference to the above embodiments, the present application is not limited to the above embodiments. Any person skilled in the art can make various modifications and changes without departing from the spirit and scope of the present application, and the scope of protection of the present application should be defined by the scope of claims.

Claims

1. A multi-layered structure of a silicon carbide wave absorbing material, characterized in that, The multilayer structure carbonized silicon wave absorbing material comprises the following raw materials in percentage by mass: 40-80% of silicon carbide powder, 10-40% of paraffin, 5-10% of thermoplastic resin, 1-5% of stearic acid, and 1-5% of sintering aid. The preparation method of the multilayer structure carbonized silicon wave absorbing material comprises the following steps: S1, mixing and granulation: uniformly mix the silicon carbide powder, the sintering aid and the stearic acid in a ball mill, dry, then uniformly mix the thermoplastic resin and the paraffin in a closed kneader, crush, and obtain mixed particles with a particle size of 50-500 μm; S2, extruding into a wire: add the dried mixed particles into a melt extrusion molding machine, the powder is transported forward under the action of the screw, melt mixed, and extrusion molding to obtain a silicon carbide / thermoplastic resin composite wire; S3, printing molding: put the silicon carbide / thermoplastic resin composite wire into a 3D printing device, adjust the device parameters, print under the control of a computer, and print a green body in a layer-by-layer solidification and layer-by-layer stacking manner; S4, debinding: debind the printed green body to obtain a preform; S5, sintering: place the preform in a sintering furnace, and high-temperature sintering to obtain a multilayer structure carbonized silicon wave absorbing material.

2. The multi-layered structure of the silicon carbide wave-sorbing material according to claim 1, characterized in that, The thermoplastic resin is selected from any one or more of polylactic acid, ABS, polycarbonate, nylon, polyethylene, and ethylene vinyl acetate polymer; and the sintering aid is selected from any one or more of aluminum, silicon, aluminum oxide, yttrium oxide, and carbon black.

3. The multi-layered structure of the silicon carbide wave-sorbing material according to claim 2, characterized in that, The particle size of the silicon carbide powder is 200-400 mesh, and the particle size of the thermoplastic resin is greater than 100 mesh.

4. A method of producing a multilayer structure of the silicon carbide wave absorbing material as claimed in any one of claims 1 to 3, characterized by, The preparation method comprises the following steps: S1, mixing and granulation: uniformly mix the silicon carbide powder, the sintering aid and the stearic acid in a ball mill, dry, then uniformly mix the thermoplastic resin and the paraffin in a closed kneader, crush, and obtain mixed particles with a particle size of 50-500 μm; S2, extruding into a wire: add the dried mixed particles into a melt extrusion molding machine, the powder is transported forward under the action of the screw, melt mixed, and extrusion molding to obtain a silicon carbide / thermoplastic resin composite wire; S3, printing molding: put the silicon carbide / thermoplastic resin composite wire into a 3D printing device, adjust the device parameters, print under the control of a computer, and print a green body in a layer-by-layer solidification and layer-by-layer stacking manner; S4, debinding: debind the printed green body to obtain a preform; S5, sintering: place the preform in a sintering furnace, and high-temperature sintering to obtain a multilayer structure carbonized silicon wave absorbing material.

5. The method of claim 4, wherein the multilayer structure of the SiC wave absorbing material is prepared by the steps of: In the step S1, the ball milling speed is 200-400 r / min, the drying temperature is 50-80℃, the internal mixing temperature is 120-180℃, and the rotating speed is 15-40 r / min.

6. The method of claim 4, wherein the multilayer structure of the SiC wave absorbing material is prepared by the steps of: In the step S2, the screw rotating speed of the melt extrusion molding machine is 10-20 r / min, the preheating zone temperature is 120-140℃, and the melt mixing temperature is 140-150℃.

7. The method of claim 4, wherein the multilayer structure of the SiC wave absorbing material is prepared by the steps of: In the step S3, the nozzle temperature of the 3D printing equipment is controlled at 100-200℃, the stage temperature is controlled at 20-150℃, the printing speed is 10-50 mm / s, and the single layer thickness is 0.1-0.2 mm.

8. The method of claim 4, wherein the multilayer structure of the SiC wave absorbing material is prepared by the steps of: In the step S4, the green body is heated to 150-250℃ at a heating rate of 1-5℃ / min in a debinding furnace, and then heated to 500-700℃ at a heating rate of 0.2-1℃ / min, and kept for 1-2 h to obtain a preform; in the step S5, the preform is placed in a sintering furnace and heated to 1900-2200℃ at a heating rate of 2-5℃ / min, and kept for 1-3 h to obtain the multi-layered structure silicon carbide wave-absorbing material.

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