CN111170743B

CN111170743B - Silicon carbide infrared radiation ceramic material and preparation method thereof

Info

Publication number: CN111170743B
Application number: CN202010061183.3A
Authority: CN
Inventors: 陈健; 祝明; 黄政仁; 朱云洲; 姚秀敏; 陈忠明; 刘学建
Original assignee: Shanghai Institute of Ceramics of CAS
Current assignee: Shanghai Institute of Ceramics of CAS
Priority date: 2020-01-19
Filing date: 2020-01-19
Publication date: 2021-08-31
Anticipated expiration: 2040-01-19
Also published as: CN111170743A

Abstract

The invention relates to a silicon carbide infrared radiation ceramic material and a preparation method thereof, wherein the silicon carbide infrared radiation ceramic material comprises the following raw materials:β-SiC and MgO-Al₂O₃‑SiO₂An auxiliary agent; preferably comprising: 76.5-95 wt% of beta-SiC, 0-8.5 wt% of AlN, 5-15 wt% of MgO-Al₂O₃‑SiO₂And the sum of the contents of the components is 100 wt%.

Description

Silicon carbide infrared radiation ceramic material and preparation method thereof

Technical Field

The invention relates to a silicon carbide infrared radiation ceramic material and a preparation method thereof, in particular to a silicon carbide ceramic material with high infrared emissivity and a preparation method thereof, belonging to the field of infrared radiation ceramics.

Background

The infrared radiation ceramic material is an inorganic material with high emissivity or characteristic emissivity in an infrared band, and is an important functional material. The infrared radiation ceramic material has the characteristics of excellent infrared radiation performance, chemical stability, high-temperature stability and the like, and can be widely applied to the fields of infrared light sources, infrared heaters, thermophotovoltaic radiators, spacecraft thermal control coatings, satellite-borne microwave calibration sources, nuclear fusion calibration sources, LED heat dissipation substrates and the like.

For example: in a high-temperature furnace, most of heat transfer is caused by radiation, the high-emissivity coating is coated on the surface of a metal or refractory substrate, so that the heat radiation efficiency of the furnace can be effectively improved, the heat loss is obviously reduced, the tempering distribution in the furnace is more uniform, an infrared radiation coating material can play a role in protecting the substrate, the maintenance is reduced, and the service life of a furnace body is prolonged, the infrared radiation material developed by American CRC company can save energy by 10-30% when being applied to an industrial furnace, and meanwhile, the infrared radiation coating material can protect the substrate of a furnace lining to a certain extent, and the service life of the furnace lining can be prolonged by 1-4 times; in the field of hypersonic aircrafts, the hypersonic aerocraft has the outstanding characteristics that the heat transfer to the surface of the aerocraft is realized in the flying process, the heat energy can be reduced by increasing the radiation and conduction heat transfer of the surface, and the high emissivity material can play an effective role in the heat dissipation process; in addition, the infrared radiation coating with high emissivity can be used for the LED heat dissipation substrate to well solve the heat dissipation problem of a power LED, and the infrared radiation material can also be used as an antibacterial building material and has certain application in textiles.

In recent years, related research on infrared radiation materials is rapidly developed, wherein the emissivity of a wave band of 8-20 μm is over 0.9, while the radiation performance of the wave band of 1-8 μm is poor and is only about 0.5, and the emissivity is not high enough under a high temperature condition.

SiC has the advantages of high strength, high heat conductivity, high vacuum adaptability, high elastic modulus, low thermal expansion coefficient, excellent thermal shock resistance, corrosion resistance, oxidation resistance and the like, and is an important high-temperature structural material. SiC is a good infrared radiation material, has high infrared emissivity in all bands, and has high emissivity in the 2.5-8 mu m band. The SiC material has excellent performance and potential to be used as a better substitute in the application field of the existing infrared radiation material. However, the emissivity of the silicon carbide material in the middle band is low, and the lowest point is only about 0.2-0.3 at normal temperature, which is a problem that the SiC infrared radiation material needs to be solved urgently. For example, patent 1 (Chinese publication No. CN110078514A) discloses a silicon carbide ceramic with normal emissivity not less than 0.85 in the wavelength range of 1-22 μm. First, the emissivity is measured under high temperature, and the higher the temperature is, the larger the emissivity of the material is, and there is a large difference. Secondly, the tested wave band is 1-22 μm, and the emissivity of the silicon carbide after the wave band is 15 microns is very high and is close to 1, so that the total emissivity is greatly improved to a certain extent. In fact, the silicon carbide obtained in patent 1 is still low (e.g. only 0.69) at 2.5-16 μm.

Disclosure of Invention

Aiming at the problems, the invention aims to provide a silicon carbide ceramic infrared radiation material with high mid-band emissivity and a preparation method thereof.

In one aspect, the invention provides a silicon carbide infrared radiation ceramic material, which comprises the following raw materials: beta-SiC and MgO-Al₂O₃-SiO₂An auxiliary agent; preferably comprising: 76.5-95 wt% of beta-SiC, 0-8.5 wt% of AlN, 5-15 wt% of MgO-Al₂O₃-SiO₂And the sum of the contents of the components is 100 wt%.

Preferably, the MgO-Al₂O₃-SiO₂The auxiliary agent comprises the following raw material components: 10 to 30wt% of MgO and 15 to 40wt% of Al₂O₃、20～60wt％SiO₂The sum of the contents of all the components is 100 wt%.

Preferably, the silicon carbide infrared radiation ceramic material comprises the following raw materials: 80-90 wt% of beta-SiC, 0-6 wt% of AlN, and 5-15 wt% of MgO-Al₂O₃-SiO₂And the sum of the contents of the components is 100 wt%.

Preferably, the silicon carbide infrared radiation ceramic material has an infrared emissivity of 0.75-0.84 at a normal temperature of 2.5-16 μm; the density of the silicon carbide infrared radiation ceramic material is 2.01-2.50 g/cm³The bending strength is 68-210 MPa.

On the other hand, the invention provides a preparation method of the silicon carbide infrared radiation ceramic material, which comprises the following steps:

(1) selecting beta-SiC powder and AlN powder as raw material powder, mixing, and carrying out solid solution reaction at 1700-2000 ℃ to obtain solid solution powder;

(2) mixing the obtained solid solution powder with MgO-Al₂O₃-SiO₂Mixing the auxiliary agents to obtain mixed powder;

(3) and pressing and molding the obtained mixed powder, and then performing vacuum de-bonding and sintering to obtain the silicon carbide ceramic material with high infrared emissivity.

In the invention, firstly, the beta-SiC powder and the AlN powder are subjected to solid solution reaction at 1700-2000 ℃ so that the AlN powder is firstly dissolved in the beta-SiC powder in a solid solution way,to avoid the subsequent vacuum debonding and sintering process with MgO-Al₂O₃-SiO₂The oxides of all the components in the auxiliary agent react. Further, the introduction of an AlN impurity element into an SiC crystal destroys the lattice periodicity, resulting in a decrease in the symmetry of lattice vibration, while the enhancement of non-simple harmonic vibration widens the vibration absorption band, thereby promoting the vibration absorption of the lattice. Meanwhile, the existence of the AlN impurity element causes the electronic energy states of the regions to be different from those of other regions, and is favorable for forming impurity energy levels in forbidden band gaps of electrons. The formation of the impurity energy level can provide convenient conditions for the transition of holes and electrons in a valence band, so that the concentration of free carriers in the crystal can be improved, the infrared absorption of the free carriers in the SiC crystal can be improved, namely, the infrared absorption performance of the crystal is improved, and the crystal is formed by the kirchhoff law:

it is known that a good absorber is necessarily a good radiator, and thus, the infrared emissivity of the material is improved. Then solid solution powder and MgO-Al are mixed₂O₃-SiO₂Mixing the auxiliary agents, pressing and forming, and then carrying out vacuum de-bonding and sintering. MgO-Al of specific composition during sintering₂O₃-SiO₂The system can further form cordierite dispersed in the SiC matrix, and the cordierite with high emissivity in a wave band of 8-14 mu m is further realized, namely a material compounding method is adopted, so that the silicon carbide infrared radiation ceramic material can be in different temperature ranges and different wavelength ranges, and the infrared radiation capability of the material is complemented and enhanced.

Preferably, the mass contents of the beta-SiC powder and the AlN powder are respectively 90-100 wt% and 0-10 wt%, and the sum of the mass percentages is 100wt%, which is calculated according to the raw material components of the silicon carbide infrared radiation ceramic material.

Preferably, the solid solution powder and MgO-Al are calculated according to the raw material components of the silicon carbide infrared radiation ceramic material₂O₃-SiO₂Mass content of the auxiliary85-95 wt% and 5-15 wt% respectively, and the sum of the mass percentages is 100 wt%.

Preferably, according to MgO-Al₂O₃-SiO₂Raw material components of the auxiliary agent are weighed MgO powder and Al₂O₃Powder and SiO₂Mixing the powder to obtain the MgO-Al₂O₃-SiO₂And (4) an auxiliary agent.

Preferably, the grain diameter of the beta-SiC powder is 0.5 to 1 mu m; the particle size of the AlN powder is 1-2 mu m; the particle size of the MgO powder is 1-3 μm; the Al is₂O₃The particle size of the powder is 100-200 nm; the SiO₂The particle size of the powder is 1 to 3 μm.

Preferably, the atmosphere of the solid solution reaction is an inert atmosphere, preferably an argon atmosphere; the gas pressure of the solid solution reaction is 40-75 mbar; the time of the solid solution reaction is 2-4 hours.

Preferably, the raw material powder or the mixed powder further comprises a binder; the binder is selected from at least one of phenolic resin, polyvinyl alcohol PVA and polyvinyl butyral PVB; the addition amount of the binder is not more than 8wt% of the total mass of the raw material powder. The binder is added into the raw material powder, so that the binder and the raw material powder are uniformly mixed and simultaneously wrapped on the surfaces of the beta-SiC powder and the AlN powder, the binder is used as a carbon source to be cracked in the subsequent solid solution reaction process to generate nano-scale residual carbon, the carbon and a silicon dioxide layer on the surface of the silicon carbide powder are subjected to reduction reaction to generate silicon carbide and carbon monoxide gas, aluminum nitride is in contact with the surface of fresh silicon carbide powder and further promotes the solid solution reaction to enter a silicon carbide lattice, and the XRD result has no AlN characteristic peak as can be proved in figure 1.

Preferably, the compression molding mode is dry compression molding or/and cold isostatic pressing, and preferably, the dry compression molding is performed before the cold isostatic pressing.

Preferably, the pressure of the dry pressing is 5 to 20MPa, and the pressure of the cold isostatic pressing is 180 to 200 MPa.

Preferably, the temperature of the vacuum de-bonding is 700-1000 ℃, the time is 0.5-2 hours, and the vacuum degree is-5-10 Pa.

Preferably, the sintering atmosphere is an inert atmosphere, preferably an argon atmosphere; the pressure of the inert atmosphere is 40-75 mbar; the sintering temperature is 1400-1950 ℃; the sintering time is 1-3 hours.

Has the advantages that:

in the invention, the silicon carbide infrared radiation ceramic material has higher infrared emissivity, and is sintered at low temperature to obtain a product, thereby greatly reducing the cost investment. At the same time, doped MgO-Al₂O₃-SiO₂The cordierite structure formed by the system enables the prepared silicon carbide material to have a lower thermal expansion coefficient and a higher thermal conductivity, and the prepared silicon carbide ceramic has certain strength and wide application prospect.

Drawings

FIG. 1 is an XRD spectrum of solid solution powders with different AlN contents obtained at 2000 ℃, wherein, no AlN peak is found in the XRD spectrum of the powders with different AlN contents, thus showing that AlN is solid dissolved in the silicon carbide crystal lattice;

FIG. 2 is a chart showing the IR emissivity of SiC IR-radiation ceramic material prepared from the solid solution powder of AlN at 1950 deg.C, in which MgO-Al is shown₂O₃-SiO₂The emissivity of the silicon carbide ceramic prepared by the system with the sintering aid is greatly improved (the silicon carbide ceramic can be distinguished from the lowest point, and the lowest emissivity value of intrinsic silicon carbide ceramic is 0.2-0.3), and the emissivity of the silicon carbide ceramic is improved to a certain extent by introducing AlN;

FIG. 3 is a chart showing the infrared emissivity of a silicon carbide infrared radiation ceramic material prepared by solid solution powders with different AlN contents at 1480 ℃ at normal temperature, and comparing with FIG. 2, it can be seen that the emissivity difference still exists whether AlN is doped or not, and the difference is that all the emissivity is improved compared with that at 1950 ℃.

Detailed Description

The present invention is further illustrated by the following examples, which are to be understood as merely illustrative and not restrictive.

Book of JapaneseIn the beginning, the raw material components of the silicon carbide infrared radiation ceramic material comprise: 76.5 to 95wt% of beta-SiC, 0 to 8.5wt% of AlN, and 5 to 15wt% of MgO-Al₂O₃-SiO₂And the sum of the contents of the components is 100 wt%. Wherein, MgO-Al₂O₃-SiO₂The auxiliary agent is MgO and Al₂O₃And SiO₂The mixed powder of (1). Preferably, MgO-Al₂O₃-SiO₂The auxiliary agent comprises the following raw material components: 10 to 30wt% of MgO and 15 to 40wt% of Al₂O₃、20～60wt％SiO₂The sum of the contents of all the components is 100 wt%.

In an alternative embodiment, the feedstock composition of the silicon carbide infrared radiating ceramic material preferably comprises: 80-90 wt% of SiC, 0-6 wt% of AlN, and 5-15 wt% of MgO-Al₂O₃-SiO₂The sum of the contents of all the components is 100 percent.

In one embodiment of the present invention, the beta-SiC powder and the AlN powder are subjected to a solid solution reaction under normal pressure sintering conditions, and MgO-Al is used₂O₃-SiO₂The system is used as a sintering aid and added into the powder prepared by the solid solution reaction for normal pressure sintering to obtain the silicon carbide infrared radiation ceramic material with excellent performance. The preparation method of the silicon carbide infrared radiation ceramic material provided by the invention is exemplarily described below.

Mixing 90-100 wt% of beta-SiC powder and 0-10 wt% of AlN powder according to different proportions, and simultaneously adding absolute ethyl alcohol as a solvent for ball milling to obtain mixed slurry 1 with the solid content of 40-50 wt%. And directly drying the mixed slurry 1 or performing spray granulation to obtain powder to be solid-dissolved (raw material powder). In the ball milling process, SiC balls with certain gradation are added as ball milling media, and the ball milling time can be 12 hours. The grain diameter of the beta-SiC powder can be 0.5-1 mu m. The AlN powder has a particle size of 1 to 2 μm.

In an alternative embodiment, in the mixed slurry 1, a binder is preferably added as a carbon source in an amount of 0 to 8wt% (preferably 0 to 6 wt%) based on the total mass of the raw material powder to promote the solid solution reaction. The binder may be at least one of phenolic resin, polyvinyl alcohol PVA, and polyvinyl butyral PVB. Wherein the binder may be added in the form of a solution, such as a phenolic resin solution.

And placing the powder to be solid-dissolved in a high-purity graphite crucible, and carrying out solid-solution reaction in a normal-pressure sintering furnace to obtain the solid-solution powder. Wherein the specific parameters of the solid solution reaction are as follows: the temperature of the solid solution reaction is controlled to be 1800-2000 ℃, the heat preservation time is 2-4 h, and the furnace pressure is controlled to be 40-75 mbar in an inert atmosphere (such as argon atmosphere). Preferably, the temperature rise rate in the solid solution reaction process is 2-8 ℃/min. If the AlN powder and the MgO-Al are directly added into the beta-silicon carbide at the same time₂O₃-SiO₂And the AlN powder is wrapped by the oxide assistant and cannot reach the preliminarily designed solid solution in the silicon carbide crystal lattice.

10-30 wt% of MgO and 15-40 wt% of Al are taken₂O₃、20～60wt％SiO₂Mixing the powder, adding absolute ethyl alcohol, and performing ball milling by using SiC balls for 6-12 hours to obtain mixed slurry 2. Placing the obtained mixed slurry 2 in an oven, drying for 12-24 hours at 70 ℃, and sieving the dried slurry with a sieve of 80-120 meshes to obtain MgO-Al₂O₃-SiO₂And (4) an auxiliary agent. The particle size of the MgO powder may be 1 to 3 μm. Al (Al)₂O₃The particle size of the powder can be 100-200 nm. SiO 2₂The particle size of the powder can be 1-3 μm.

Selecting solid solution powder obtained by 85-95 wt% of solid solution reaction and 5-15 wt% of MgO-Al₂O₃-SiO₂The system liquid phase auxiliary agent is taken as a raw material, a proper amount of absolute ethyl alcohol is added, and ball milling and mixing are carried out to obtain mixed slurry 2. And drying and sieving the obtained mixed slurry 2 to obtain mixed powder. For example, the mixed slurry 2 is put in an oven, dried at 70 ℃ for 12 hours, and the dried slurry is passed through a 100-mesh sieve to obtain a mixed powder. In the ball milling process, SiC balls with certain gradation are also used for ball milling, and the ball milling time can be 12 hours.

In an alternative embodiment, a binder is preferably added to the mixed slurry 2 in an amount of 0 to 8wt% (preferably 0 to 6 wt%) based on the total mass of the mixed powder. The binder may be at least one of phenolic resin, polyvinyl alcohol PVA, and polyvinyl butyral PVB. Wherein the binder may be added in the form of a solution, such as a phenolic resin solution.

And directly pressing and molding the mixed powder to obtain a blank. Wherein the compression molding mode can be dry compression molding or/and cold isostatic pressing. Wherein, the pressure of dry pressing molding can be 5-20 MPa. The pressure of the cold isostatic pressing can be 180-200 MPa. As an example of the press molding of a blank, dry press molding is performed at a pressure of 5 to 20MPa, and then cold isostatic pressing is performed at a pressure of 180 to 200MPa, wherein the medium of the cold isostatic pressing is oil or water.

And placing the blank into a high-purity graphite crucible, and performing vacuum debonding in a normal-pressure debonding furnace. The specific parameters of the vacuum debonding process are as follows: controlling the de-bonding temperature to be 700-1000 ℃, the heat preservation time to be 0.5-2 h, and controlling the furnace pressure to be-5-10 Pa.

Placing the blank after vacuum debonding in a high-purity graphite crucible, and adopting a powder embedding process to contain 10-20 wt% of MgO-Al₂O_3-SiO₂And (3) wrapping the vacuum-debonded green body with SiC powder of the system liquid phase auxiliary agent, and further placing the green body in a normal-pressure sintering furnace for sintering to prepare the silicon carbide ceramic material with high infrared emissivity. Wherein, the sintering process parameters comprise: controlling the sintering temperature to 1400-1950 ℃, the heat preservation time to 1-3 h, and controlling the furnace pressure to 40-75 mbar in an inert atmosphere (such as argon atmosphere).

According to the invention, the obtained silicon carbide ceramic material has high infrared emissivity, and the normal-temperature normal infrared emissivity of the silicon carbide ceramic material can be 0.75-0.84 in a spectral range of 2.5-16 mu m by testing with an IR-2 dual-band emissivity tester. The density of the silicon carbide infrared radiation ceramic material measured by an Archimedes drainage method can be 2.01-2.50 g/cm³. The bending strength of the prepared silicon carbide infrared radiation ceramic material measured by a three-point bending method can be 68-210 MPa.

The present invention will be described in detail by way of examples. It is also to be understood that the following examples are illustrative of the present invention and are not to be construed as limiting the scope of the invention, which is defined by the appended claimsThe invention is intended to cover by the appended claims some insubstantial modifications and adaptations of the invention. The specific process parameters and the like of the following examples are also only one example of suitable ranges, i.e., those skilled in the art can select the appropriate ranges through the description herein, and are not limited to the specific values exemplified below. In the following examples, MgO-Al is mentioned, unless otherwise specified₂O₃-SiO₂The ball milling and mixing process of the auxiliary agent comprises the following steps: taking 20 wt% MgO and 25 wt% Al₂O₃、55wt％SiO₂Mixing the powder, adding absolute ethyl alcohol, and performing ball milling by using SiC balls for 12 hours; placing the obtained mixed slurry in an oven, drying for 12 hours at 70 ℃, sieving the dried slurry with a 100-mesh sieve to obtain MgO-Al₂O₃-SiO₂Liquid phase system assistant (MgO-Al for short)₂O₃-SiO₂Auxiliaries), i.e., MgO, Al₂O₃And SiO₂The mixed powder of (1).

Example 1

Taking 200g of 100wt% beta-SiC and 0wt% AlN, and 4g of phenolic resin, using SiC balls with a certain gradation as a ball milling medium, adding absolute ethyl alcohol as a solvent, carrying out ball milling for 12 hours, drying and sieving to obtain raw material powder;

putting the obtained raw material powder into a normal pressure sintering furnace, carrying out solid solution reaction under the argon atmosphere, controlling the temperature to be 2000 ℃, and keeping the temperature for 3 hours to obtain SiC powder;

90g of the SiC powder was taken, and 10g of the MgO-Al powder obtained above was added₂O₃-SiO₂Adding an auxiliary agent, namely adding 2g of phenolic resin, using SiC balls with a certain gradation as a ball milling medium, adding absolute ethyl alcohol as a solvent, carrying out ball milling for 12 hours, drying and sieving, forming the obtained powder on a manual hydraulic press at the pressure of 8MPa, and then carrying out isostatic pressing at the pressure of 200MPa to obtain a blank;

and (3) performing vacuum de-bonding on the obtained blank (the temperature is 900 ℃, and the heat preservation time is 0.5 hour), placing the blank into a normal-pressure sintering furnace, sintering in the argon atmosphere, controlling the sintering temperature to 1950 ℃, preserving the heat for 2 hours, controlling the temperature to 1300 ℃ by a program, preserving the heat for 2 hours, and then cooling along with the furnace, and grinding the obtained silicon carbide ceramic wafer to obtain the silicon carbide infrared radiation ceramic material.

The silicon carbide infrared radiation ceramic material has a normal temperature normal infrared emissivity of 0.75 in a spectral range of 2.5-16 mu m by an IR-2 dual-waveband emissivity measuring instrument. The bending strength of the prepared silicon carbide infrared radiation ceramic material test strip (3mm multiplied by 4mm multiplied by 36mm) measured by a three-point bending method is 205 MPa. The density of the silicon carbide infrared radiation ceramic material measured by an Archimedes drainage method is 2.47g/cm³。

Example 2

Taking 200g of 96 wt% of beta-SiC and 4 wt% of AlN, taking 4g of phenolic resin, using SiC balls with a certain gradation as a ball milling medium, adding absolute ethyl alcohol as a solvent, carrying out ball milling for 12 hours, drying and sieving to obtain raw material powder;

putting the obtained raw material powder into a normal pressure sintering furnace, carrying out solid solution reaction under the atmosphere of argon, controlling the temperature to be 2000 ℃, and keeping the temperature for 3 hours to obtain SiC-AlN solid solution powder;

90g of the SiC-AlN solid solution powder was taken, and 10g of the MgO-Al obtained above was added₂O₃-SiO₂Adding an auxiliary agent, namely adding 2g of phenolic resin, using SiC balls with a certain gradation as a ball milling medium, adding absolute ethyl alcohol as a solvent, carrying out ball milling for 12 hours, drying and sieving, forming the obtained powder on a manual hydraulic press at the pressure of 8MPa, and then carrying out cold isostatic pressing at the pressure of 200MPa to obtain a blank;

The silicon carbide infrared radiation ceramic material has a normal temperature normal infrared emissivity of 0.79 within a spectral range of 2.5-16 mu m through the test of an IR-2 dual-waveband emissivity measuring instrument. The silicon carbide infrared radiation ceramic material (size 3 mm. times.4 mm. times.36 mm) had a flexural strength of 157MPa as measured by a three-point bending method. Measured by Archimedes drainage methodThe density of the silicon carbide infrared radiation ceramic material is 2.33g/cm³。

Example 3

90g of the SiC powder was taken, and 10g of the MgO-Al powder obtained above was added₂O₃-SiO₂Adding an auxiliary agent, namely adding 2g of phenolic resin, using SiC balls with a certain gradation as a ball milling medium, adding absolute ethyl alcohol as a solvent, carrying out ball milling for 12 hours, drying and sieving, forming the obtained powder on a manual hydraulic press at the pressure of 8MPa, and then carrying out cold isostatic pressing at the pressure of 200MPa to obtain a blank;

and (3) after vacuum de-bonding (the temperature is 900 ℃ and the heat preservation time is 0.5 hour), placing the obtained blank in a normal-pressure sintering furnace, sintering in the argon atmosphere, controlling the sintering temperature to 1480 ℃ and the heat preservation time to be 2 hours, controlling the temperature to 1300 ℃ by a program, preserving the heat for 2 hours, and then cooling along with the furnace, grinding the obtained silicon carbide ceramic wafer to obtain the silicon carbide infrared radiation ceramic material.

The silicon carbide infrared radiation ceramic material has a normal temperature normal infrared emissivity of 0.82 in a spectral range of 2.5-16 mu m through the test of an IR-2 dual-waveband emissivity measuring instrument. The silicon carbide infrared radiation ceramic material (3 mm. times.4 mm. times.36 mm in size) had a bending strength of 68MPa as measured by a three-point bending method. The density of the silicon carbide infrared radiation ceramic material measured by an Archimedes drainage method is 2.01g/cm³。

Example 4

The silicon carbide infrared radiation ceramic material has a normal temperature normal infrared emissivity of 0.84 in a spectral range of 2.5-16 mu m by an IR-2 dual-waveband emissivity measuring instrument. The silicon carbide infrared radiation ceramic material (size 3 mm. times.4 mm. times.36 mm) had a bending strength of 73MPa as measured by a three-point bending method. The density of the silicon carbide infrared radiation ceramic material measured by an Archimedes drainage method is 2.03g/cm³。

Claims

1. The silicon carbide infrared radiation ceramic material is characterized by comprising the following raw materials: 76.5 to 95wt% of beta-SiC, 0 to 8.5wt% of AlN, and MgO-Al in an amount of not 0 but 5 to 15wt%₂O₃-SiO₂The additive accounts for 100wt% of the total content of the components;

the MgO-Al₂O₃-SiO₂The auxiliary agent comprises the following raw material components: 10 to 30wt% of MgO and 15 to 40wt% of Al₂O₃、20～60wt% SiO₂The sum of the contents of all the components is 100 wt%;

the preparation method of the silicon carbide infrared radiation ceramic material comprises the following steps:

(3) pressing and molding the obtained mixed powder, and then performing vacuum de-bonding and sintering to obtain the silicon carbide infrared radiation ceramic material;

the silicon carbide infrared radiation ceramic material has an infrared emissivity of 0.75-0.84 at a normal temperature of 2.5-16 mu m.

2. The silicon carbide infrared radiation ceramic material as claimed in claim 1, wherein the density of the silicon carbide infrared radiation ceramic material is 2.01-2.50 g/cm³The bending strength is 68-210 MPa.

3. Silicon carbide infrared radiating ceramic material according to claim 1, characterised in that it is MgO-Al in terms of its properties₂O₃-SiO₂Raw material components of the auxiliary agent are weighed MgO powder and Al₂O₃Powder and SiO₂Mixing the powder to obtain the MgO-Al₂O₃-SiO₂And (4) an auxiliary agent.

4. The silicon carbide infrared radiation ceramic material of claim 3, wherein the particle size of the beta-SiC powder is 0.5 to 1 μm; the particle size of the AlN powder is 1-2 mu m; the particle size of the MgO powder is 1-3 μm; the Al is₂O₃The particle size of the powder is 100-200 nm; the SiO₂The particle size of the powder is 1 to 3 μm.

5. The silicon carbide infrared radiating ceramic material of claim 1, wherein the atmosphere of the solution reaction is an inert atmosphere; the gas pressure of the solid solution reaction is 40-75 mbar; the time of the solid solution reaction is 2-4 hours.

6. The silicon carbide infrared radiating ceramic material of claim 5, wherein the atmosphere of the solid solution reaction is an argon atmosphere.

7. The silicon carbide infrared radiation ceramic material as claimed in claim 1, wherein the raw material powder or mixed powder further comprises a binder; the binder is selected from at least one of phenolic resin, polyvinyl alcohol PVA and polyvinyl butyral PVB; the addition amount of the binder is not more than 8wt% of the total mass of the raw material powder or the mixed powder.

8. The silicon carbide infrared radiation ceramic material as claimed in claim 1, wherein the temperature of the vacuum de-bonding is 700 ℃ to 1000 ℃, the time is 0.5 to 2 hours, and the vacuum degree is-5 to 10 Pa.

9. The silicon carbide infrared radiating ceramic material of claim 1, wherein the sintering atmosphere is an inert atmosphere; the pressure of the inert atmosphere is 40-75 mbar; the sintering temperature is 1400-1950 ℃; the sintering time is 1-3 hours.

10. The silicon carbide infrared radiating ceramic material of claim 9, wherein the sintering atmosphere is an argon atmosphere.