阅读说明：本技术 一种高绝缘碳化硅纤维增强陶瓷复合材料的制备方法 (Preparation method of high-insulation silicon carbide fiber reinforced ceramic composite material ) 是由 吴宝林 侯振华 吴迪 于 2021-11-01 设计创作，主要内容包括：本发明提供了一种高绝缘碳化硅纤维增强陶瓷复合材料的制备方法,包括以下步骤：前驱体的制备、表面复合氧化镧粒子的碳化硅纤维的制备、表面复合氧化镧晶须的碳化硅纤维的制备、高绝缘碳化硅纤维增强陶瓷的制备。本发明还提供了上述方法制得的高绝缘碳化硅纤维增强陶瓷复合材料。本发明提供的碳化硅纤维增强陶瓷复合材料,通过在碳化硅陶瓷中分散碳化硅纤维大大提高了材料的韧性,在碳化硅纤维表面复合氧化镧晶须,降低了碳化硅纤维的介电参数,同时在碳化硅陶瓷中分散氧化硅等材料,进一步降低了碳化硅陶瓷的介电参数,提高了绝缘性。(The invention provides a preparation method of a high-insulation silicon carbide fiber reinforced ceramic composite material, which comprises the following steps: the preparation method comprises the steps of preparing a precursor, preparing silicon carbide fibers with lanthanum oxide particles compounded on the surfaces, preparing silicon carbide fibers with lanthanum oxide whiskers compounded on the surfaces, and preparing high-insulation silicon carbide fiber reinforced ceramics. The invention also provides the high-insulation silicon carbide fiber reinforced ceramic composite material prepared by the method. According to the silicon carbide fiber reinforced ceramic composite material provided by the invention, the toughness of the material is greatly improved by dispersing the silicon carbide fibers in the silicon carbide ceramic, the lanthanum oxide whiskers are compounded on the surface of the silicon carbide fibers, the dielectric parameters of the silicon carbide fibers are reduced, and meanwhile, materials such as silicon oxide and the like are dispersed in the silicon carbide ceramic, so that the dielectric parameters of the silicon carbide ceramic are further reduced, and the insulativity is improved.)

1. A preparation method of a high-insulation silicon carbide fiber reinforced ceramic composite material is characterized by comprising the following steps: the method comprises the following steps:

(1) preparing a precursor: dropwise adding alkali liquor into a lanthanum salt aqueous solution with the concentration of 0.4-0.6mol/L while stirring in a water bath at the temperature of 5-15 ℃, and adjusting the pH value to 11-14; adjusting the temperature of the water bath to 25-35 ℃, adding a surfactant, and stirring at constant temperature for 40-60min to obtain a precursor solution;

(2) preparing silicon carbide fiber with lanthanum oxide particles compounded on the surface: adding silicon carbide fiber into 0.4-0.6mol/L lanthanum salt aqueous solution, stirring and simultaneously dripping alkali liquor, and adjusting the pH value to 9-11; transferring into a high-pressure kettle, heating at 120 ℃ for 6-8h, cooling to room temperature, taking out the silicon carbide fiber, alternately washing with water and ethanol, and drying to obtain the silicon carbide fiber with the surface compounded with lanthanum oxide particles;

(3) preparing the silicon carbide fiber with the lanthanum oxide whisker compounded on the surface: soaking the silicon carbide fiber with the surface compounded with the lanthanum oxide particles into the precursor solution prepared in the step (1), preserving heat for 2-6h at the temperature of 100 ℃ and 150 ℃, cooling to room temperature, taking out, alternately washing with water and ethanol, and drying to obtain the silicon carbide fiber with the surface compounded with the lanthanum oxide whiskers;

(4) preparing high-insulation silicon carbide fiber reinforced ceramic: and (3) uniformly mixing the silicon carbide fiber with the surface compounded with the lanthanum oxide whisker prepared in the step (3), a boron compound, silicon nitride and silicon dioxide, putting the mixture into a dry pressing mould, prepressing the mixture for 0.5 to 3min at 4 to 6MPa to obtain a blank, putting the blank into a crucible, vacuumizing, heating, vacuum sintering and cooling to obtain the lanthanum oxide whisker.

2. The method for preparing a high-insulation silicon carbide fiber reinforced ceramic composite material according to claim 1, wherein the method comprises the following steps: in the step (1), the lanthanum salt is lanthanum chloride or lanthanum nitrate; the alkali liquor is 0.1-0.3mol/L sodium hydroxide aqueous solution; the surfactant is FSN-100 fluorocarbon surfactant, and the dosage of the surfactant is 2-4% of the volume of the mixed solution.

3. The method for preparing a high-insulation silicon carbide fiber reinforced ceramic composite material according to claim 1, wherein the method comprises the following steps: in the step (2), the lanthanum salt is lanthanum chloride or lanthanum nitrate; the alkali liquor is 0.1-0.3mol/L sodium hydroxide aqueous solution.

4. The method for preparing a high-insulation silicon carbide fiber reinforced ceramic composite material according to claim 1, wherein the method comprises the following steps: in the step (4), the dosage of the raw materials is as follows: 100 parts of silicon carbide fiber with lanthanum oxide whisker compounded on the surface, 3-4 parts of boron compound, 1-2 parts of silicon nitride and 1-3 parts of silicon dioxide, which are calculated by weight.

5. The method for preparing a high-insulation silicon carbide fiber reinforced ceramic composite material according to claim 1, wherein the method comprises the following steps: in the step (4), the boron compound is boron nitride or boron carbide.

6. The method for preparing a high-insulation silicon carbide fiber reinforced ceramic composite material according to claim 1, wherein the method comprises the following steps: in the step (4), the vacuum sintering conditions are as follows: the vacuum degree is below 0.01Pa, and the sintering temperature is 2000-2200 ℃; the sintering time is 10-24 h.

7. The method for preparing a high-insulation silicon carbide fiber reinforced ceramic composite material according to claim 1, wherein the method comprises the following steps: in the step (4), the temperature rise condition is as follows: the temperature rise rate is 50-60 ℃/min when the temperature rises from room temperature to 1650-1850 ℃, and the temperature rise rate is 10-20 ℃/min when the temperature rises from 1650-1850 ℃ to 2000-2200 ℃; cooling conditions are as follows: the cooling rate is 10-20 ℃/min from 2000-2200 ℃ to 1650-1850 ℃, and the cooling rate is 50-60 ℃/min from 1650-1850 ℃ to room temperature.

8. A high insulation silicon carbide fibre reinforced ceramic composite material obtainable by the process of any one of claims 1 to 7.

9. High insulating silicon carbide fibre reinforced ceramic composite material which characterized in that includes: comprises silicon carbide doped with boron compounds, silicon nitride and silicon dioxide, and silicon carbide fiber dispersed in the silicon carbide and compounded with lanthanum oxide whiskers on the surface.

Technical Field

The invention belongs to the field of new materials, and particularly relates to a preparation method of a high-insulation silicon carbide fiber reinforced ceramic composite material and a prepared aluminum oxide fiber reinforced silicon carbide ceramic material.

Background

Ceramic materials have many advantages not comparable to other materials, but their brittleness is an inevitable fatal disadvantage, and the brittleness of ceramic materials greatly affects the reliability and consistency of material properties. Ceramic materials are polycrystalline structures consisting of ionic or covalent bonds and lack a slip system which promotes the deformation of the material, which, once subjected to an applied load, together with the presence of micro-defects on the surface of the material, which are difficult to avoid by ceramic processes, may constitute sources of cracks at which stresses are concentrated at the tips of these cracks, and in which there are no other systems which consume external energy, exchanged only by new free energy, which is the energy absorbed by the new surface formed by the propagation of the crack tip, with the result that the crack rapidly propagates and is manifested as a so-called brittle fracture. It follows that the brittleness of a ceramic material is determined by the chemical bonding properties of the substance and its microstructure. Therefore, in order to make silicon carbide exhibit its excellent wear resistance, its brittleness, i.e., toughness of the silicon carbide ceramic, should be overcome first.

In order to improve the toughness of silicon carbide ceramics, a great deal of scientific research is carried out. The fiber reinforcement is a development direction for overcoming the brittleness problem of ceramic materials, and the fiber reinforced ceramic matrix composite not only maintains the advantages of high temperature resistance, corrosion resistance, low expansion and the like of the ceramic materials, but also has the advantages of high strength, high toughness and high specific strength of fibers, and has wide application prospect. The fiber reinforced ceramic matrix composite mainly comprises reinforcement fibers, an interface layer and a matrix material, and can realize the combination of multiple performances by selecting different reinforcement fibers and ceramic matrixes, thereby meeting the requirements of aircraft parts on the performances. The fiber reinforced ceramic matrix composite prepared aiming at the high temperature requirement mainly comprises: carbon fiber, quartz fiber, and silicon carbide fiber reinforced ceramic matrix composites.

The silicon carbide fiber reinforced ceramic composite material is an ideal material for heat-resistant structural members in the fields of aerospace, nuclear energy and the like by virtue of the advantages of high specific strength, high-temperature oxidation resistance, ablation resistance, low density and the like. The loss characteristics of silicon carbide fibers are related to their electrical properties, and for applications in the insulation field, it is desirable that the resistivity of the silicon carbide fibers be as high as possible to reduce the microwave losses incurred by the silicon carbide fibers. Although the resistivity of the silicon carbide fiber is far higher than that of the carbon fiber, the resistivity of the silicon carbide fiber prepared by the traditional method is between 1 and 10 omega cm, and the dielectric loss of the silicon carbide fiber is still large. The Si-C-O structure in the silicon carbide fiber and the carbon-rich layer at the surface are the main factors affecting the resistivity of the silicon carbide fiber. Currently, researchers have increased the resistivity of silicon carbide fibers by changing the sintering atmosphere of silicon carbide fibers, reducing the surface carbon content, and increasing the oxygen content. The existence of the Si-C-O structure can cause the resistivity of the silicon carbide fiber to be increased, so that the silicon carbide fiber can be applied to the fields of insulation and dielectric. However, the Si-C-O structure has poor high-temperature stability, can be decomposed at high temperature to form SiO2 and CO, and has poor temperature resistance compared with KD-I fiber, and higher requirements are provided for the preparation process of coatings and composite materials.

Disclosure of Invention

The technical problem is as follows: in order to overcome the defects of the prior art, the invention provides a preparation method of a high-insulation silicon carbide fiber reinforced ceramic composite material and an alumina fiber reinforced silicon carbide ceramic material prepared by the preparation method.

The technical scheme is as follows: the invention provides a preparation method of a high-insulation silicon carbide fiber reinforced ceramic composite material, which comprises the following steps:

(1) preparing a precursor: dropwise adding alkali liquor into a lanthanum salt aqueous solution with the concentration of 0.4-0.6mol/L while stirring in a water bath at the temperature of 5-15 ℃, and adjusting the pH value to 11-14; adjusting the temperature of the water bath to 25-35 ℃, adding a surfactant, and stirring at constant temperature for 40-60min to obtain a precursor solution;

(2) preparing silicon carbide fiber with lanthanum oxide particles compounded on the surface: adding silicon carbide fiber into 0.4-0.6mol/L lanthanum salt aqueous solution, stirring and simultaneously dripping alkali liquor, and adjusting the pH value to 9-11; transferring into a high-pressure kettle, heating at 120 ℃ for 6-8h, cooling to room temperature, taking out the silicon carbide fiber, alternately washing with water and ethanol, and drying to obtain the silicon carbide fiber with the surface compounded with lanthanum oxide particles;

(3) preparing the silicon carbide fiber with the lanthanum oxide whisker compounded on the surface: soaking the silicon carbide fiber with the surface compounded with the lanthanum oxide particles into the precursor solution prepared in the step (1), preserving heat for 2-6h at the temperature of 100 ℃ and 150 ℃, cooling to room temperature, taking out, alternately washing with water and ethanol, and drying to obtain the silicon carbide fiber with the surface compounded with the lanthanum oxide whiskers;

(4) preparing high-insulation silicon carbide fiber reinforced ceramic: and (3) uniformly mixing the silicon carbide fiber with the surface compounded with the lanthanum oxide whisker prepared in the step (3), a boron compound, silicon nitride and silicon dioxide, putting the mixture into a dry pressing mould, prepressing the mixture for 0.5 to 3min at 4 to 6MPa to obtain a blank, putting the blank into a crucible, vacuumizing, heating, vacuum sintering and cooling to obtain the lanthanum oxide whisker.

In the step (1), the lanthanum salt is lanthanum chloride or lanthanum nitrate; the alkali liquor is 0.1-0.3mol/L sodium hydroxide aqueous solution; the surfactant is FSN-100 fluorocarbon surfactant, and the dosage of the surfactant is 2-4% of the volume of the mixed solution.

In the step (2), the lanthanum salt is lanthanum chloride or lanthanum nitrate; the alkali liquor is 0.1-0.3mol/L sodium hydroxide aqueous solution.

In the step (4), the dosage of the raw materials is as follows: 100 parts of silicon carbide fiber with lanthanum oxide whisker compounded on the surface, 3-4 parts of boron compound, 1-2 parts of silicon nitride and 1-3 parts of silicon dioxide, which are calculated by weight.

In the step (4), the boron compound is boron nitride or boron carbide.

In the step (4), the vacuum sintering conditions are as follows: the vacuum degree is below 0.01Pa, and the sintering temperature is 2000-2200 ℃; the sintering time is 10-24 h.

In the step (4), the temperature rise condition is as follows: the temperature rise rate is 50-60 ℃/min when the temperature rises from room temperature to 1650-1850 ℃, and the temperature rise rate is 10-20 ℃/min when the temperature rises from 1650-1850 ℃ to 2000-2200 ℃; cooling conditions are as follows: the cooling rate is 10-20 ℃/min from 2000-2200 ℃ to 1650-1850 ℃, and the cooling rate is 50-60 ℃/min from 1650-1850 ℃ to room temperature.

The invention also provides the high-insulation silicon carbide fiber reinforced ceramic composite material prepared by the method.

The invention also provides a high-insulation silicon carbide fiber reinforced ceramic composite material, which comprises the following components in percentage by weight: comprises silicon carbide doped with boron compounds, silicon nitride and silicon dioxide, and silicon carbide fiber dispersed in the silicon carbide and compounded with lanthanum oxide whiskers on the surface.

Has the advantages that: according to the silicon carbide fiber reinforced ceramic composite material provided by the invention, the toughness of the material is greatly improved by dispersing the silicon carbide fibers in the silicon carbide ceramic, the lanthanum oxide whiskers are compounded on the surface of the silicon carbide fibers, the dielectric parameters of the silicon carbide fibers are reduced, and meanwhile, materials such as silicon oxide and the like are dispersed in the silicon carbide ceramic, so that the dielectric parameters of the silicon carbide ceramic are further reduced, and the insulativity is improved.

Drawings

FIG. 1 is an SEM image of a high-insulation silicon carbide fiber reinforced ceramic composite material prepared by the method.

Detailed Description

The present invention is further explained below.

Example 1

The preparation method of the high-insulation silicon carbide fiber reinforced ceramic composite material comprises the following steps:

(1) preparing a precursor: dropwise adding alkali liquor into a lanthanum salt aqueous solution with the concentration of 0.5mol/L while stirring in a water bath at the temperature of 10 ℃, and adjusting the pH value to 12; then adjusting the temperature of the water bath to 30 ℃, adding a surfactant, and stirring for 50min at constant temperature to obtain a precursor solution;

wherein the lanthanum salt is lanthanum chloride; the alkali liquor is 0.2mol/L sodium hydroxide aqueous solution; the surfactant is FSN-100 fluorocarbon surfactant, and the dosage of the surfactant is 3% of the volume of the mixed solution.

(2) Preparing silicon carbide fiber with lanthanum oxide particles compounded on the surface: adding silicon carbide fiber into 0.5mol/L lanthanum salt aqueous solution, stirring and simultaneously dripping alkali liquor, and adjusting the pH value to 10; transferring the mixture into a high-pressure kettle, heating the mixture for 7 hours at the temperature of 120 ℃, cooling the mixture to room temperature, taking out the silicon carbide fiber, alternately washing the silicon carbide fiber with water and ethanol, and drying the washed silicon carbide fiber to obtain the silicon carbide fiber with the surface compounded with lanthanum oxide particles;

wherein the lanthanum salt is lanthanum chloride; the alkali liquor is 0.2mol/L sodium hydroxide aqueous solution.

(3) Preparing the silicon carbide fiber with the lanthanum oxide whisker compounded on the surface: soaking the silicon carbide fiber with the surface compounded with lanthanum oxide particles into the precursor solution prepared in the step (1), preserving heat for 4h at the temperature of 125 ℃, cooling to room temperature, taking out, alternately washing with water and ethanol, and drying to obtain the silicon carbide fiber with the surface compounded with lanthanum oxide whiskers;

(4) preparing high-insulation silicon carbide fiber reinforced ceramic: uniformly mixing the silicon carbide fiber with the surface compounded with the lanthanum oxide whisker prepared in the step (3), a boron compound, silicon nitride and silicon dioxide, putting the mixture into a dry pressing mould, prepressing the mixture for 2min at 5MPa to obtain a blank, putting the blank into a crucible, vacuumizing, heating, sintering in vacuum, and cooling to obtain the lanthanum oxide whisker-containing silicon carbide fiber;

wherein, the raw material dosage is as follows: 100 parts of silicon carbide fiber with lanthanum oxide whisker compounded on the surface, 3.5 parts of boron compound, 1.5 parts of silicon nitride and 2 parts of silicon dioxide in parts by weight; the boron compound is boron nitride or boron carbide; temperature rising conditions are as follows: when the temperature is increased from the room temperature to 1750 ℃, the heating rate is 55 ℃/min, and when the temperature is increased from 1750 ℃ to 2100 ℃, the heating rate is 15 ℃/min; the vacuum sintering conditions are as follows: vacuum degree below 0.01Pa, sintering temperature is 2100 ℃; the sintering time is 18 h; cooling conditions are as follows: the cooling rate is 15 ℃/min from 2100 ℃ to 1750 ℃, and the cooling rate is 55 ℃/min from 1750 ℃ to room temperature.

Example 2

The preparation method of the high-insulation silicon carbide fiber reinforced ceramic composite material comprises the following steps:

(1) preparing a precursor: dropwise adding alkali liquor into a lanthanum salt aqueous solution with the concentration of 0.6mol/L while stirring in a water bath at the temperature of 5 ℃, and adjusting the pH value to 11; then adjusting the temperature of the water bath to 35 ℃, adding a surfactant, and stirring at constant temperature for 60min to obtain a precursor solution;

wherein the lanthanum salt is lanthanum nitrate; the alkali liquor is 0.1mol/L sodium hydroxide aqueous solution; the surfactant is FSN-100 fluorocarbon surfactant, and the dosage of the surfactant is 2% of the volume of the mixed solution.

(2) Preparing silicon carbide fiber with lanthanum oxide particles compounded on the surface: adding silicon carbide fiber into 0.4mol/L lanthanum salt aqueous solution, stirring and simultaneously dripping alkali liquor, and adjusting the pH value to 11; transferring the silicon carbide fiber into a high-pressure kettle, heating the silicon carbide fiber at 120 ℃ for 8h, cooling the silicon carbide fiber to room temperature, taking out the silicon carbide fiber, alternately washing the silicon carbide fiber with water and ethanol, and drying the silicon carbide fiber to obtain the silicon carbide fiber with the surface compounded with lanthanum oxide particles;

wherein the lanthanum salt is lanthanum nitrate; the alkali liquor is 0.1mol/L sodium hydroxide aqueous solution.

(3) Preparing the silicon carbide fiber with the lanthanum oxide whisker compounded on the surface: soaking the silicon carbide fiber with the surface compounded with lanthanum oxide particles into the precursor solution prepared in the step (1), preserving heat for 6h at the temperature of 100 ℃, cooling to room temperature, taking out, alternately washing with water and ethanol, and drying to obtain the silicon carbide fiber with the surface compounded with lanthanum oxide whiskers;

(4) preparing high-insulation silicon carbide fiber reinforced ceramic: uniformly mixing the silicon carbide fiber with the surface compounded with the lanthanum oxide whisker prepared in the step (3), a boron compound, silicon nitride and silicon dioxide, putting the mixture into a dry pressing mould, prepressing the mixture for 3min at 4MPa to obtain a blank, putting the blank into a crucible, vacuumizing, heating, sintering in vacuum, and cooling to obtain the lanthanum oxide whisker-containing silicon carbide fiber;

wherein, the raw material dosage is as follows: 100 parts of silicon carbide fiber with lanthanum oxide whisker compounded on the surface, 4 parts of boron compound, 1 part of silicon nitride and 1 part of silicon dioxide in parts by weight; the boron compound is boron nitride or boron carbide; temperature rising conditions are as follows: when the temperature is increased from room temperature to 1650 ℃, the heating rate is 50 ℃/min, and when the temperature is increased from 1650 ℃ to 2000 ℃, the heating rate is 10 ℃/min; the vacuum sintering conditions are as follows: vacuum degree below 0.01Pa, and sintering temperature of 2000 deg.C; the sintering time is 24 h; cooling conditions are as follows: the cooling rate is 10 ℃/min from 2000 ℃ to 1650 ℃, and the cooling rate is 50 ℃/min from 1650 ℃ to room temperature.

Example 3

The preparation method of the high-insulation silicon carbide fiber reinforced ceramic composite material comprises the following steps:

(1) preparing a precursor: dropwise adding alkali liquor into a lanthanum salt aqueous solution with the concentration of 0.6mol/L while stirring in a water bath at 15 ℃, and adjusting the pH value to 14; then adjusting the temperature of the water bath to 25 ℃, adding a surfactant, and stirring at constant temperature for 40min to obtain a precursor solution;

wherein the lanthanum salt is lanthanum chloride or lanthanum nitrate; the alkali liquor is 0.3mol/L sodium hydroxide aqueous solution; the surfactant is FSN-100 fluorocarbon surfactant, and the dosage of the surfactant is 4% of the volume of the mixed solution.

(2) Preparing silicon carbide fiber with lanthanum oxide particles compounded on the surface: adding silicon carbide fiber into 0.6mol/L lanthanum salt aqueous solution, stirring and simultaneously dripping alkali liquor, and adjusting the pH value to 9; transferring the mixture into a high-pressure kettle, heating the mixture for 6 hours at 120 ℃, cooling the mixture to room temperature, taking out silicon carbide fibers, alternately washing the silicon carbide fibers with water and ethanol, and drying the silicon carbide fibers to obtain the silicon carbide fibers with the surface compounded with lanthanum oxide particles;

wherein the lanthanum salt is lanthanum chloride; the alkali liquor is 0.3mol/L sodium hydroxide aqueous solution.

(3) Preparing the silicon carbide fiber with the lanthanum oxide whisker compounded on the surface: soaking the silicon carbide fiber with the surface compounded with lanthanum oxide particles into the precursor solution prepared in the step (1), preserving heat for 2h at the temperature of 150 ℃, cooling to room temperature, taking out, alternately washing with water and ethanol, and drying to obtain the silicon carbide fiber with the surface compounded with lanthanum oxide whiskers;

(4) preparing high-insulation silicon carbide fiber reinforced ceramic: uniformly mixing the silicon carbide fiber with the surface compounded with the lanthanum oxide whisker prepared in the step (3), a boron compound, silicon nitride and silicon dioxide, putting the mixture into a dry pressing mould, prepressing the mixture for 0.5min at 6MPa to obtain a blank, putting the blank into a crucible, vacuumizing, heating, sintering in vacuum, and cooling to obtain the lanthanum oxide whisker-containing silicon carbide fiber;

wherein, the raw material dosage is as follows: 100 parts of silicon carbide fiber with lanthanum oxide whisker compounded on the surface, 3 parts of boron compound, 2 parts of silicon nitride and 3 parts of silicon dioxide, wherein the silicon carbide fiber is calculated by weight parts; the boron compound is boron nitride or boron carbide; temperature rising conditions are as follows: when the temperature is increased from room temperature to 1850 ℃, the heating rate is 60 ℃/min, and when the temperature is increased from 1850 ℃ to 2200 ℃, the heating rate is 20 ℃/min; the vacuum sintering conditions are as follows: vacuum degree below 0.01Pa, sintering temperature 2200 ℃; the sintering time is 10 h; cooling conditions are as follows: the cooling rate is 20 ℃/min from 2200 ℃ to 1850 ℃, and the cooling rate is 60 ℃/min from 1850 ℃ to room temperature.

Comparative example

The preparation method of the silicon carbide fiber reinforced ceramic composite material comprises the following steps: uniformly mixing silicon carbide fiber, boron compound, silicon nitride and silicon dioxide, putting into a dry pressing mould, prepressing for 2min at 5MPa to obtain a blank body, putting the blank body into a crucible, vacuumizing, heating, sintering in vacuum, and cooling to obtain the silicon carbide fiber/boron compound/silicon nitride/silicon dioxide composite material;

wherein, the raw material dosage is as follows: 100 parts of silicon carbide fiber, 3.5 parts of boron compound, 1.5 parts of silicon nitride and 2 parts of silicon dioxide in parts by weight; the boron compound is boron nitride or boron carbide; temperature rising conditions are as follows: when the temperature is increased from the room temperature to 1750 ℃, the heating rate is 55 ℃/min, and when the temperature is increased from 1750 ℃ to 2100 ℃, the heating rate is 15 ℃/min; the vacuum sintering conditions are as follows: vacuum degree below 0.01Pa, sintering temperature is 2100 ℃; the sintering time is 18 h; cooling conditions are as follows: the cooling rate is 15 ℃/min from 2100 ℃ to 1750 ℃, and the cooling rate is 55 ℃/min from 1750 ℃ to room temperature.

Examples of the experiments

The product properties of examples 1 to 3 and comparative example 1 were tested. The results are as follows:

note:

the dielectric property test method comprises the following steps: the dielectric property of the composite material is tested by adopting a rectangular waveguide method, the essence of the method is to test the reflection coefficient and the transmission coefficient of the ports at two sides, and the dielectric constant of the composite material is calculated by a transmission/reflection method model. Agilent N5230C vector network analyzer was used for the test. The actual test band is the X band (8.2-12.4GHz), corresponding to a sample size of 22.86mm by 10.16mm by 2 mm.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.