Silicon carbide ceramic composite material with high thermal shock resistance sintered at medium-low temperature, preparation method and application

Abstract

The application provides a low-temperature sintered silicon carbide ceramic composite material with high thermal shock resistance, a preparation method and application, and belongs to the technical field of ceramic materials. a O b Al c Si d Ca e Na f , wherein a, b, c, d, e and f are atomic contents of corresponding elements, 8.68<=a<=23.81, 45.30<=b<=57.79, 9.83<=c<=17.85, 13.20<=d<=20.29, 0.77<=e<=2.03 and 0<=f<=0.64; the composite material has a pore structure and contains nano-level particles; in an infrared spectrum, 1166cm ‑1 shoulder peaks show Si-O stretching vibration, the strongest peak at 1091cm ‑1 shows Si(Al)-O bond stretching vibration, the secondary peak at 820-824cm ‑l shows Si-O-Si symmetric stretching vibration, and the peak at 781cm ‑1 shows Si-Si bond stretching vibration. The composite material has high thermal shock resistance, high oxidation resistance and high wear resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ceramic materials, and particularly relates to a medium-low temperature sintered silicon carbide ceramic composite material with high thermal shock resistance, a preparation method and application. BACKGROUND

[0002] The burner used in coal-fired power generation is the key to long-period, full-load and safe production of a boiler. In the process of coal-fired power generation, the wind speed of coal powder is usually large, generally greater than 20 m / s, and the part of the burner through which the coal powder flows and the nozzle part of the burner belong to the strong wear part of small particle materials and will be subjected to frequent thermal shock. For example, the nozzle part will be subjected to radiation temperature of up to 800 DEG C to 1250 DEG C from the furnace. In order to improve the wear resistance of the burner at high temperature, the existing technology usually adopts heat-resistant alloy cast steel parts, but the heat-resistant alloy cast steel parts are not resistant to wear at a small angle (0 DEG to 30 DEG), that is, the angle between the flow direction of the coal powder and the surface of the burner, resulting in serious wear of the metal parts of the part through which the coal powder flows of the burner, so that the combustion efficiency of the burner is reduced. The nozzle at the hot end will produce thermal deformation, oxidation and serious wear, and further cause deflection of the jet flame, resulting in damage to the water-cooled wall and other accidents, and even forced shutdown.

[0003] Chinese patent application (CN113446599A) discloses a composite ceramic burner and a preparation method thereof, the composite ceramic burner is prepared from a composite ceramic material; the composite ceramic material is composed of the following components in mass percentage: silicon carbide 55-75%, brown corundum 10-20%, aluminate cement 5-15%, high-temperature-resistant stainless steel fiber 2-5%, and auxiliary materials 5-10%; the composite ceramic burner is prepared by the following steps: 1) raw material preparation: prepare silicon carbide, brown corundum powder, aluminate cement, high-temperature-resistant stainless steel fiber, and auxiliary materials in proportion; 2) calculate the weight of the concentrator, weigh and proportionally mix the silicon carbide, brown corundum, and aluminate cement, then pour them into a mixer, add 4-6% of the total amount of raw materials, start the mixer to stir, stir for 12-18 minutes, add high-temperature-resistant stainless steel fiber after the material in the mixer becomes paste, and stir for another 3-8 minutes to discharge; 3) coal powder concentrator outer frame pouring: paste 40g of film-coated paper in the inner cavity of the previously prepared outer frame mold, place it on a vibration table, fix the mold, start the vibration table, pour the stirred material into the mold gate until the mold gate is filled; 4) guide plate pouring: the guide plate is poured separately from the coal powder concentrator outer frame, and the method of step 3) is used to pour the guide plate; 5) demolding: demolding is performed after 12 hours at room temperature, and the demolded product is placed for 2 days to dry; 6) drying: the demolded blank is placed in a drying room at 75-85°C for 2 days; 7) low-temperature sintering treatment: place the dried guide plate and outer frame blank into a heat treatment furnace for sintering treatment; 8) insert the sintered guide plate into the sintered outer frame to assemble, and use inorganic glue to glue them together to form a whole concentrator. In its preparation process, the highest sintering temperature is 1380°C, however, when the sintering temperature exceeds 1350°C, the steel fiber may partially melt and oxidize, losing the reinforcing effect, and the increased brown corundum has a larger expansion coefficient than silicon carbide, and a smaller thermal conductivity than silicon carbide, which may generate a large internal stress during the use of the composite ceramic burner, causing the product to be loose and cracked.

[0004] Currently, how to sinter at medium and low temperatures to improve the thermal shock resistance, oxidation resistance, and wear resistance of silicon carbide ceramic materials is a problem that needs to be further solved. The above information disclosed in the background section is only used to strengthen the understanding of the background of the present application, and therefore it can include information that does not constitute the relevant technology known to those skilled in the art. SUMMARY

[0005] In view of the problems in the prior art, the present application first provides a silicon carbide ceramic composite material sintered at medium temperature, which has high thermal shock resistance, high oxidation resistance, and high wear resistance, and its chemical composition includes C a O b Al c Si d Ca e Naf Wherein, a, b, c, d, e, f are the atomic content of the corresponding elements, 8.68≤a≤23.81, 45.30≤b≤57.79, 9.83≤c≤17.85, 13.20≤d≤20.29, 0.77≤e≤2.03, 0≤f≤0.64; the composite material has a pore structure and contains nano-sized particles, and in the infrared spectrum, 1166cm -1 The shoulder shows the stretching vibration of Si-O, and the strongest peak at 1091cm -1 The shoulder shows the stretching vibration of Si(Al)-O bond, the secondary strong peak at 820cm -1 The shoulder shows the stretching vibration of Si-O-Si symmetric, and the peak at 781cm -1 The shoulder shows the stretching vibration of Si-Si bond.

[0006] Wherein, the pore structure in the composite material can eliminate the stress generated when the composite material is used in high temperature environment, and improve the thermal shock resistance.

[0007] Further, the nano-sized particles are sheet-like particles, that is, including sheet-like particles and stacked sheet-like particles, and the size is 200nm-500nm, for example, the size can be 200nm, 220nm, 280nm, 300nm, 350nm, 400nm, 450nm, 480nm, 500nm. The sheet-like particles can increase the contact area between each other, so that the composite material formed by the sheet-like particles is more dense and compact, and the strength and wear resistance of the composite material are improved.

[0008] Further, the radial size of the pore structure is 1μm-10μm, for example, the radial size can be 2μm, 4μm, 5μm, 6μm, 8nm, 9μm, 10μm.

[0009] Further, the silicon carbide ceramic composite material includes a crystal structure, which can promote the sintering activity of the material during preparation, and obtain a silicon carbide ceramic composite material with high strength and high wear resistance.

[0010] Further, in the infrared spectrum, the peak in the range of 480-650cm -1 Range shows the bending vibration mode of Si-O.

[0011] The application also provides a preparation method of the above-mentioned silicon carbide ceramic composite material with high thermal shock resistance sintered at medium and low temperature, which comprises the following steps:

[0012] (1) Put the main material: get 55-75 parts of pre-processed silicon carbide graded particles, 10-12 parts of 200-300 mesh silicon carbide powder, 2-10 parts of aluminate cement, 2-10 parts of aluminum oxide powder, 2-10 parts of silicon dioxide powder and 0.5-5 parts of reinforcing material by weight fraction; wherein the pre-processed silicon carbide graded particles include silicon carbide sand with different particle sizes.

[0013] (2) Put the auxiliary material: get 0.5-3 parts of compound antioxidant sintering aid and 3-5 parts of water by weight fraction, the compound antioxidant sintering aid includes boron carbide powder.

[0014] (3) Mix the main material and the auxiliary material, and place it in the mold to form a green body.

[0015] (4) Brush the anti-oxidation coating on the surface of the green body, and perform low-temperature sintering, the temperature of the low-temperature sintering is not higher than 750℃.

[0016] Among them, the aluminate cement in the main material can be calcium aluminate cement, which can improve the high temperature performance of silicon carbide ceramic composite material, so that the material is resistant to high temperature. The grade of calcium aluminate cement can be selected from any one of CA50, CA60, CA70 and CA80.

[0017] Among them, the pre-processed silicon carbide graded particles can be taken as 55 parts, 60 parts, 65 parts, 66 parts, 70 parts, 72 parts, 74 parts, 75 parts. The 200-300 mesh silicon carbide powder can be taken as 10 parts, 11 parts, 11.5 parts, 12 parts. The aluminate cement can be taken as 2 parts, 3 parts, 5 parts, 6 parts, 8 parts, 10 parts. The aluminum oxide powder can be taken as 2 parts, 3 parts, 5 parts, 6 parts, 8 parts, 10 parts. The silicon dioxide powder can be taken as 2 parts, 3 parts, 5 parts, 6 parts, 8 parts, 9 parts, 10 parts. The reinforcing material can be taken as 0.5 parts, 1 parts, 1.2 parts, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 3.8 parts, 4 parts, 4.5 parts, 4.7 parts, 5 parts.

[0018] Among them, the compound antioxidant sintering aid in the auxiliary material can be 0.5 parts, 1.2 parts, 1.5 parts, 2 parts, 2.5 parts, 3 parts. The water in the auxiliary material can be 3 parts, 4 parts, 5 parts.

[0019] Further, before the main material is put in, the preparation method further comprises: preparing the pretreated silicon carbide graded particles, including: obtaining 12-15 parts of silicon carbide sand with a diameter of 3.35-4.75 mm, 27-35 parts of silicon carbide sand with a diameter of 1.18-2.8 mm, 15-22 parts of silicon carbide sand with a diameter of 0.5-0.7 mm, and 1-3 parts of modified sodium type silica sol, and mixing, then stirring and drying to obtain the pretreated silicon carbide graded particles.

[0020] That is, in the embodiment of the present application, the pretreated silicon carbide graded particles contain silicon carbide sand with different levels of particle size, according to the principle of similarity and compatibility, the silicon carbide sand with smaller particle size can be filled in the gap of the silicon carbide sand with larger particle size, thereby improving the strength. And the silicon carbide sand with multiple particle sizes can reduce the bonding limit and correspond to multiple size wear particles, thereby enhancing the wear resistance.

[0021] The silicon carbide sand with a diameter of 3.35-4.75 mm can be 12 parts, 13 parts, 14 parts, or 15 parts. The silicon carbide sand with a diameter of 1.18-2.8 mm can be 27 parts, 28 parts, 29 parts, 30 parts, 31 parts, 32 parts, 33 parts, 34 parts, or 35 parts. The silicon carbide sand with a diameter of 0.5-0.7 mm can be 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, 21 parts, or 22 parts. The modified sodium type silica sol can be 1 part, 1.5 parts, 2 parts, 2.5 parts, or 3 parts.

[0022] Further, the modified sodium type silica sol includes silicon dioxide and sodium silicate. For example, a sol obtained by uniformly mixing silica sol and sodium silicate. The silica sol is a dispersion liquid of silicon dioxide particles in water or other solvents, and the modified sodium type silica sol of the embodiment of the present application is obtained by adding a predetermined amount of sodium silicate. In some embodiments of the present application, the weight content of SiO2 in the modified sodium type silica sol can be 30%, but can also be other contents, such as 25%, 40%, etc., which can be prepared according to actual needs by those skilled in the art, and is not specially limited here. The modified sodium type silica sol is used to treat the particles, so that the particles have a layer of highly active SiO2 on the surface, and the particles are more easily sintered at low temperature.

[0023] Further, the low-temperature sintering of the green body coated with the anti-oxidation coating in step (4) comprises: heating the green body, heating from room temperature to a first preset temperature, and keeping the temperature at the first preset temperature for 4-6 hours, then heating to a second preset temperature, and keeping the temperature at the second preset temperature for 4-6 hours, and naturally cooling to room temperature.

[0024] That is, after brushing the green body with the anti-oxidation coating, low-temperature sintering is performed. In the embodiment of the present application, the first preset temperature is 130-160°C, for example, the first preset temperature is 130°C, 135°C, 140°C, 145°C, 150°C, 155°C, 160°C, and the temperature rising speed from room temperature to the first preset temperature is 30-40°C / h, for example, the temperature rising speed can be 30°C / h, 33°C / h, 35°C / h, 37°C / h, 38°C / h, 40°C / h, the second preset temperature is 650-750°C, and the temperature rising speed from the first preset temperature to the second preset temperature is 30-40°C / h. For example, the second preset temperature is 650°C, 680°C, 700°C, 720°C, 730°C, 750°C, and the temperature rising speed of the second preset temperature can be 30°C / h, 33°C / h, 35°C / h, 37°C / h, 38°C / h, 40°C / h. The holding time of the first preset temperature and the second preset temperature can be 4h, 4.5h, 4.8h, 5h, 5.5h, 5.8h, 6h, respectively.

[0025] Silicon carbide and the reinforcing material are easy to oxidize at high temperature, for example, above 1300°C, while in the embodiment of the present application, the temperature of low-temperature sintering is not higher than 750°C, thus the oxidation of silicon carbide and the reinforcing material can be avoided, the strength of the composite material is further increased, and the oxidation resistance and thermal shock resistance of the silicon carbide composite material are improved. In the embodiment of the present application, the first preset temperature is 130-160°C, and the holding time is 4-6h, which can remove the moisture on the surface of the green body and the surface of the internal material (such as silicon carbide), and release the crystal water of the internal material of the green body in the process of slow temperature rising, so that the green body is further dried, and the silicon carbide ceramic composite material with high strength and high wear resistance can be obtained when the second preset temperature of 650-750°C is reached.

[0026] In addition, the composite anti-oxidation sintering aid in the embodiment of the present application includes boron carbide powder (B4C), which can be oxidized to generate B2O3 at a lower temperature, and B2O3 can generate a glass phase with silicon oxide in the material of the green body, so as to promote the sintering of the material in the green body at a lower temperature (650-750°C), that is, the sintering activity of the material is improved, and thus the green body can be sintered at low temperature to obtain a silicon carbide ceramic material with high strength, high wear resistance and high thermal shock resistance, avoiding high-temperature oxidation.

[0027] Further, the anti-oxidation sintering aid further comprises at least one of aluminum powder (Al), silicon powder (Si), aluminum oxide powder (Al2O3), silicon oxide powder (SiO2), and aluminum-silicon alloy powder (AlSi). The anti-oxidation sintering aid will melt and recrystallize during sintering, which reduces the recrystallization temperature. Therefore, these materials can promote the sintering activity of the green body at low temperature, and obtain high-strength and high-wear-resistance silicon carbide ceramic materials. The silicon oxide powder refers to the particle size of the silicon oxide reaching micron or nanometer level.

[0028] Further, the weight content of the B4C powder in the anti-oxidation sintering aid is more than 50%, for example, 60%, 70%, 80%, etc., to ensure better low-temperature sintering performance. For example, the anti-oxidation sintering aid comprises boron carbide powder and aluminum powder, and the weight ratio of the boron carbide powder to the aluminum powder is 1:1. For another example, the anti-oxidation sintering aid comprises boron carbide powder and aluminum-silicon alloy powder, and the weight ratio of the boron carbide powder to the aluminum-silicon alloy powder is 1:1.

[0029] Further, the reinforcing material in the main material comprises at least one of steel fiber (for example, 310s stainless steel fiber), silicon nitride whisker, silicon carbide whisker, and aluminum oxide whisker. These materials can further enhance the strength of the silicon carbide ceramic composite material. Since the above-mentioned low-temperature sintering temperature is low, these reinforcing materials (for example, steel fiber) will not be oxidized and melted, which can significantly improve the strength of the silicon carbide ceramic composite material, increase the toughness, and avoid cracking.

[0030] Further, the above-mentioned reinforcing materials are heat-resistant materials. For example, the steel fiber is a heat-resistant steel fiber, which can be subjected to solid solution treatment and surface passivation. The diameter of the cross section of the steel fiber is 0.2mm~0.5mm, for example, 0.2mm, 0.25mm, 0.3mm, 0.35mm, 0.4mm, 0.45mm, or 0.5mm. The steel fiber is in end hook shape or corrugated shape to increase the pullout work of the steel fiber. The material of the steel fiber can be selected from any one of the following grades: 16Cr25N, 08Cr18Ni9, 20Cr23Ni13, 08Cr25Ni20, or 08Cr17Ni12Mo2.

[0031] Further, the anti-oxidation coating layer comprises mullite micropowder, micropowder of andalusite and modified sodium type silica sol, and the weight ratio is 4:1:5. The modified sodium type silica sol is the same as the modified sodium type silica sol in the pre-processed silicon carbide graded particles in the above embodiment, which will not be repeated here. The above micropowder and modified sodium type silica sol are mixed and stirred, water or other solvents can be added according to the actual situation to obtain the required viscosity to form the anti-oxidation coating layer. The thickness of the anti-oxidation coating layer brushed on the green body is 0.2mm~2mm, in addition to the above two end values, the thickness can also be 0.5mm, 1mm, 1.2mm, 1.5mm, 1.8mm, the thickness value can be selected by the person skilled in the art according to the actual situation, which is not specially limited here. The anti-oxidation coating layer can prevent the silicon carbide and the reinforcing material in the silicon carbide ceramic composite material from being oxidized by oxygen in the working medium during sintering, further ensuring the strength of the silicon carbide ceramic composite material and improving the oxidation resistance.

[0032] Further, the auxiliary material further comprises 0.1~0.3 parts of a rheological modifier, such as 0.1 parts, 0.15 parts, 0.2 parts, 0.25 parts, 0.3 parts, the rheological modifier comprises at least one of sodium tripolyphosphate, sodium hexametaphosphate and polynaphthalene sulfonate. By adding the rheological modifier, the mixing between the various components is smoother, the water consumption is reduced, the subsequent sintering time is further shortened, and the construction performance is improved.

[0033] Further, the auxiliary material can further comprise 0.1~0.3 parts of a retarder, such as 0.1 parts, 0.15 parts, 0.2 parts, 0.25 parts, 0.3 parts, the retarder comprises at least one of citric acid and oxalic acid.

[0034] In order to adjust the construction time and product performance of the silicon carbide ceramic composite material at different temperatures (seasons), for example, when the environmental temperature is high, the activity of each component is high, a retarder can be added to reasonably control the solidification time of the material to achieve the best performance.

[0035] Further, the auxiliary material can further comprise 0.01~0.05 parts of an accelerator, such as 0.01 parts, 0.02 parts, 0.03 parts, 0.04 parts, 0.05 parts. When the environmental temperature is low, the activity of each component is low, after adding the accelerator, the activity between each component can be improved, the solidification time is shortened, and the best performance is achieved. The brand of the accelerator can be KAD-20 or CS-511. The accelerator can be anhydrous lithium chloride, lithium carbonate, etc.

[0036] Therefore, the retarder or the accelerator can be selected according to the actual situation to ensure that the silicon carbide ceramic composite material has more excellent performance and has more sufficient construction time, reasonable hydration time, and improved product performance.

[0037] Further, the auxiliary material further comprises 0.2-0.6 parts of an anti-explosion agent and 4.5-6.5 parts of water; wherein the anti-explosion agent comprises at least one of polypropylene fiber and polyethylene fiber.

[0038] The addition of the anti-explosion agent in the auxiliary material can avoid the explosion of the blank (preform) during use, thereby prolonging the service life of the silicon carbide ceramic composite material. The anti-explosion agent can be at least one of polypropylene fiber and polyethylene fiber, with a length of 2-10 mm (e.g., 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm) and a diameter of 10-50 μm (e.g., 10 μm, 20 μm, 30 μm, 40 μm, 50 μm).

[0039] The anti-explosion agent can be 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, and the water can be 4.5 parts, 4.8 parts, 5 parts, 5.5 parts, 5.8 parts, 6 parts, 6.2 parts, 6.5 parts.

[0040] The application further provides an application of the silicon carbide ceramic composite material sintered at a medium-low temperature and having high thermal shock resistance in a burner.

[0041] Further, the silicon carbide ceramic composite material can be used to form a burner, or at least to form a part through which high-temperature coal powder flows and a nozzle of the burner.

[0042] According to the above technical solution, the silicon carbide ceramic composite material and the preparation method thereof have at least one of the following beneficial effects:

[0043] The silicon carbide ceramic composite material has a porous structure, which can eliminate the stress generated when the composite material is used in a high temperature environment, and improve the thermal shock resistance. In the preparation process, the pre-processed silicon carbide graded particles contain silicon carbide sand with different particle sizes and reinforcing materials, which can enhance the wear resistance of the silicon carbide ceramic composite material. In the sintering process, the compounded antioxidant sintering aid includes boron carbide powder, which can be oxidized to generate B2O3 at a lower temperature. B2O3 can form a glass phase with silicon oxide in the green body material, improve the sintering activity of the material, and promote the sintering of the material in the green body at a lower temperature (650-750°C) to achieve the required performance, avoid high temperature oxidation, eliminate internal stress of the product, improve the thermal shock resistance of the silicon carbide ceramic composite material, and increase the toughness. By brushing an anti-oxidation coating on the surface of the green body, the silicon carbide and reinforcing materials in the silicon carbide ceramic composite material can be further prevented from being oxidized by oxygen in the working medium during sintering, further ensuring the strength of the silicon carbide ceramic composite material. Therefore, the silicon carbide ceramic composite material prepared by the above method has higher oxidation resistance, higher strength and wear resistance, and longer service life. BRIEF DESCRIPTION OF DRAWINGS

[0044] The above and other features and advantages of the present application will become more apparent by describing in detail example embodiments thereof with reference to the attached drawings.

[0045] Figure 1 The XRD test graph of the silicon carbide ceramic composite material of Example 1.

[0046] Figure 2 The infrared test graph of the silicon carbide ceramic composite material of Example 1.

[0047] Figure 3 The EDS test graph of the silicon carbide ceramic composite material of Example 1.

[0048] Figure 4 The SEM test of the silicon carbide ceramic composite material of Example 1 Figure 1 .

[0049] Figure 5 The SEM test of the silicon carbide ceramic composite material of Example 1 Figure 2 .

[0050] Figure 6 The TEM test graph of the silicon carbide ceramic composite material of Example 1.

[0051] Figure 7 The XRD test graph of the silicon carbide ceramic composite material of Example 2.

[0052] Figure 8 The infrared test graph of the silicon carbide ceramic composite material of Example 2.

[0053] Figure 9 EDS test pattern of the silicon carbide ceramic composite material of Example 2.

[0054] Figure 10 SEM test pattern of the silicon carbide ceramic composite material of Example 2.

[0055] Figure 11 TEM test pattern of the silicon carbide ceramic composite material of Example 2.

[0056] Figure 12 EDS test pattern of the silicon carbide ceramic composite material of Example 3.

[0057] Figure 13 SEM test pattern of the silicon carbide ceramic composite material of Example 3.

[0058] Figure 14 EDS test pattern of the silicon carbide ceramic composite material of Example 4.

[0059] Figure 15 SEM test pattern of the silicon carbide ceramic composite material of Example 4.

[0060] Figure 16 EDS test pattern of the silicon carbide ceramic composite material of Example 5.

[0061] Figure 17 EDS test pattern of the silicon carbide ceramic composite material of Example 6. DETAILED DESCRIPTION

[0062] Example embodiments now will be described more fully hereinafter with reference to the accompanying drawings; however, these embodiments can be implemented in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the example embodiments to those skilled in the art. Like reference numerals refer to like elements throughout the several views of the drawings, and description of the same or like elements can be simplified in some instances through cross references among the drawings and text.

[0063] The operations / steps in the examples are not necessarily performed in the order described in the figures. For example, some operations / steps can be further divided, and some operations / steps can be combined or partially combined, so the actual order of performance can be changed according to actual conditions.

[0064] Performance test

[0065] 1. XRD (X-ray diffraction) test

[0066] Instrument name: X-ray diffractometer

[0067] Make: D8 ADVANCE (Bruker, Germany)

[0068] Test condition: Cu-Ka radiation (0.15406 nm).

[0069] 2. Fourier transform infrared spectroscopy (FTIR) test

[0070] Instrument name: Fourier transform infrared spectrometer

[0071] Make: VERTEX 70, Germany

[0072] Test condition: Wavenumber range: 4000-400 cm -1 ; Resolution: 2 cm -1 ; Scanning times: 32 times.

[0073] 3. EDS (energy dispersive spectrometer) analysis

[0074] Instrument name: Field emission transmission electron microscope & energy dispersive spectrometer

[0075] Make: ZEISS Sigma 300 & OXFORD Ultim® Max100

[0076] Test condition: Accelerating voltage is 200 kV.

[0077] 4. SEM (scanning electron microscope) test

[0078] Instrument name: Scanning electron microscope

[0079] Make: ZEISS Sigma 300

[0080] Test condition: Accelerating voltage is 10 kV.

[0081] 5. TEM (transmission electron microscope) test

[0082] Instrument name: Transmission electron microscope

[0083] Make: Tecnai G 2 F20 S-TWIN

[0084] Test condition: The sample is dispersed in water after ultrasonic treatment; accelerating voltage is 200 kV.

[0085] 6. Thermal shock resistance test

[0086] According to GB / T30873-2014, the water quenching method is used to test the thermal shock resistance of the silicon carbide ceramic composite material of the application, as follows.

[0087] Apparatus: (1) Test furnace, which can be an electric heating furnace, with uniform temperature distribution in the sample area, ensuring that the temperature difference between any two points on the heated end of the sample is not greater than 15℃, and the uniform temperature area should be sufficient to accommodate more than 3 samples for simultaneous testing. The thermocouple temperature measuring end is 10mm~20mm from the heated end of the sample. (2) Flowing water tank, which can accommodate multiple samples for simultaneous quenching, and ensure that the temperature rise of water flowing into and out of the tank is not greater than 10℃, and the tank has a support for placing the sample, and the surface of the support is not less than 20mm from the bottom of the tank to ensure normal flow of cooling water, and the depth of water in the tank should ensure that the sample is fully immersed in water. (3) Manipulator or clamp. (4) Sample cooling rack, which is a steel rack paved with parallel refractory bricks, and can hold 50mm×50mm cylindrical samples. (5) Electric heating air drying oven, room temperature~300℃. (6) Thermometer, accurate to 1℃. (7) Steel ruler, accurate to 1mm.

[0088] Sample: The sample is prepared according to the provisions of YB / T5116, and the sample size is 40mm×40mm×160mm.

[0089] Test procedure: (1) Dry the sample in the electric heating drying oven at 110℃±5℃ until constant weight. (2) Preheat the heating furnace to 1100℃±10℃, and after 15min of heat preservation, quickly move the sample into the uniform temperature area in the furnace cavity. The samples should not be stacked and should be separated from each other, and the distance between the samples should be not less than 10mm, and the distance between the sample and the heating body surface should be not less than 30mm. (3) After the sample is put into the furnace, the furnace temperature should not decrease by more than 50℃, and should be restored to the test temperature within 5min. The sample should be kept at the test temperature for 20min. (4) Quickly immerse the sample in 5℃~35℃ flowing water, and adjust the water flow to ensure that the temperature rise of water flowing into and out of the tank is not greater than 10℃. (5) After the sample is rapidly cooled in the water tank for 3min, it is immediately taken out and placed on the cooling rack, and the air is placed for not less than 5min. When the sample is rapidly cooled, the furnace door should be closed in time to keep the furnace temperature within 10℃ of the test temperature. (6) When the sample has been kept in the air for 5min and the furnace temperature has been restored to the test temperature, the sample can be quickly moved into the furnace, and the above rapid cooling and heating process is repeated until the test is completed. (7) During the heat exchange process, the sample should not be mechanically damaged. (8) The test is stopped when visible cracks appear on the sample or the agreed number of times is reached.

[0090] Example 1

[0091] The preparation method of the silicon carbide ceramic composite material of the present embodiment comprises the following steps (1)~(4).

[0092] (1) Put in the main materials

[0093] The following components are weighed by weight parts: 66 parts of pre-processed silicon carbide graded particles, 11 parts of 200 mesh silicon carbide fine powder, 8 parts of calcium aluminate cement, 8 parts of aluminum oxide micro powder, 7 parts of silicon dioxide micro powder and 4 parts of steel fiber.

[0094] The pre-processed silicon carbide graded particles include:

[0095] 12 parts of silicon carbide sand with a diameter of 3.35mm~4.75mm, 32 parts of silicon carbide sand with a diameter of 1.18mm~2.8mm, 20 parts of silicon carbide sand with a diameter of 0.5mm~0.7mm and 2 parts of modified sodium type silica sol. The above different diameter silicon carbide sand and modified sodium type silica sol are mixed uniformly by stirring and then dried to obtain the pre-processed silicon carbide graded particles.

[0096] (2) Put in the auxiliary materials

[0097] The following components are weighed by weight parts: 2 parts of compound anti-oxidation sintering aid (B4C and Al powder, mass ratio 1:1), 0.2 parts of rheological modifier (sodium tripolyphosphate), 0.2 parts of retarder (citric acid), 0.5 parts of anti-explosion agent (polypropylene fiber) and 5 parts of water.

[0098] (3) Mix the main materials and auxiliary materials, and place them in the mold to form a green body.

[0099] (4) Brush a roughly 1mm thick anti-oxidation coating on the green body, which includes mullite micro powder, micro powder of andalusite and modified sodium type silica sol, with a weight ratio of 4:1:5. After brushing the anti-oxidation coating, low-temperature sintering is carried out, starting from room temperature and heating to 150℃ at a heating rate of 30℃ / h~40℃ / h. After reaching 150℃, keep the temperature for 5h, and then continue to heat to 700℃ at a heating rate of 30℃ / h~40℃ / h, keep the temperature for 5h, and then naturally cool to room temperature to obtain the silicon carbide ceramic composite material doped with steel fiber.

[0100] The silicon carbide ceramic composite material of the present embodiment is subjected to XRD test, as shown in Figure 1 , it contains a large amount of inorganic compound crystals, and the XRD peak is similar to the characteristics of olivine and kaolinite, with a strong peak at 35.5 degrees, further proving that the silicon carbide ceramic composite material of the present embodiment is a high-wear-resistant and refractory material.

[0101] As shown in Figure 2 , the infrared test shows that the 1166cm -1 -1 peak of the composite material of the present embodiment shows Si-O stretching vibration, the strongest peak at 1091cm -1 -1 shows Si(Al)-O bond stretching vibration, the secondary strong peak at 820cm -1 -1 shows Si-O-Si symmetric stretching vibration, and the peak at 781cm-1 stretching vibration of Si-Si bond, 480-650 cm -1 peaks in the range of 800-1200 cm

[0102] Figure 3 EDS spectrum of the composite material of the present embodiment is shown, combined with the EDS spectrum analysis results below:

[0103]

[0104] The chemical composition of the composite material of the present embodiment is C 16.89 O 52.22 Al 12.39 Si 17.19 Ca 1.31 Of course, in fact, the composite material of the present application can also include other trace elements or impurities, such as B, P, etc., which are within the allowable error of EDS measurement, and are not shown due to their extremely small amount.

[0105] Figure 4 The SEM photo of the present embodiment shows that the composite material has a pore structure, and the radial size (diameter) of the pore structure is about 1 μm-10 μm. Figure 5 The SEM photo of the present embodiment shows that the composite material has a pore structure, and the composite material includes a sheet-like material.

[0106] Figure 6 The TEM photo of the present embodiment further proves that the composite material includes a sheet-like particle.

[0107] The thermal shock resistance test was performed on the composite material of the present embodiment, and the results are shown in Table 1.

[0108] Table 1 Test results

[0109]

[0110] Embodiment 2

[0111] The preparation method of the silicon carbide ceramic composite material of the present embodiment includes the following steps (1)-(4).

[0112] (1) Put in the main materials

[0113] The following components are weighed by weight parts: 64 parts of pretreated silicon carbide graded particles, 11 parts of 250 mesh silicon carbide fine powder, 8 parts of calcium aluminate cement, 10 parts of aluminum oxide micro powder, 7 parts of silicon dioxide micro powder and 4 parts of steel fiber.

[0114] Among them, the pretreated silicon carbide graded particles include:

[0115] 12 parts of silicon carbide sand with a diameter of 3.35mm~4.75mm, 30 parts of silicon carbide sand with a diameter of 1.18mm~2.8mm, 20 parts of silicon carbide sand with a diameter of 0.5mm~0.7mm and 2 parts of modified sodium type silica sol. Wherein, the above different diameter silicon carbide sand and modified sodium type silica sol are mixed uniformly by stirring and then dried to obtain the pretreated silicon carbide graded particles.

[0116] (2) Put in the auxiliary materials

[0117] The following components are weighed by weight parts: 2 parts of compound antioxidant sintering aid (B4C and AlSi powder, mass ratio of 1:1), 0.2 parts of rheological modifier (sodium hexametaphosphate), 0.2 parts of retarder (citric acid), 0.5 parts of anti-explosive agent (polyethylene fiber) and 5 parts of water.

[0118] (3) Mix the main materials and auxiliary materials, and place them in the mold to form the green body.

[0119] (4) Brush a roughly 1mm thick anti-oxidation coating on the green body, which includes mullite powder, microcline powder and modified sodium type silica sol, with a weight ratio of 4:1:5. After brushing the anti-oxidation coating, low-temperature sintering is carried out, starting from room temperature and heating to 150℃ at a rate of 30℃ / h~40℃ / h. After reaching 150℃, keep the temperature for 5h, and then continue to heat to 700℃ at a rate of 30℃ / h~40℃ / h, keep the temperature for 5h, and then naturally cool to room temperature to obtain the steel fiber doped silicon carbide ceramic composite material.

[0120] The silicon carbide ceramic composite material of the present embodiment is subjected to XRD test, as shown in Figure 7 , it contains a large amount of inorganic compound crystals, and the XRD peak is similar to the characteristics of olivine and kaolinite, with a strong peak at 35.5 degrees, further proving that the silicon carbide ceramic of the present embodiment is a high wear-resistant refractory material.

[0121] As shown in Figure 8 , the infrared test shows that the composite material of the present embodiment has a strong peak at 1166cm -1 , which shows the stretching vibration of Si-O, a strong peak at 1091cm -1 , which shows the stretching vibration of Si(Al)-O bond, a secondary strong peak at 824cm -1 , which shows the symmetric stretching vibration of Si-O-Si, and peaks in the range of 480~650cm -1 , which show the bending vibration mode of Si-O.

[0122] Figure 9 The EDS spectrum of the composite material of the present embodiment is shown, and the EDS spectrum analysis results below are combined:

[0123]

[0124] The chemical composition of the composite material of the present embodiment is C 13.90 O 54.44 Al 13.30 Si 16.34 Ca 2.03 .

[0125] Figure 10 The SEM photo of the present embodiment shows that the composite material has a pore structure with a radial dimension (diameter) of about 1-10 microns.

[0126] Figure 11 The TEM photo of the present embodiment further proves that the composite material includes a sheet-like material.

[0127] Embodiment 3

[0128] The preparation method of the silicon carbide ceramic composite material of the present embodiment includes the following steps (1)-(4).

[0129] (1) Put in the main material

[0130] The following components are weighed by weight parts: 66 parts of pretreated silicon carbide graded particles, 11 parts of 300 mesh silicon carbide fine powder, 3 parts of calcium aluminate cement, 8 parts of aluminum oxide micro powder, 7 parts of silicon dioxide micro powder and 4 parts of steel fiber.

[0131] The pretreated silicon carbide graded particles include:

[0132] 12 parts of silicon carbide sand with a diameter of 3.35-4.75 mm, 32 parts of silicon carbide sand with a diameter of 1.18-2.8 mm, 20 parts of silicon carbide sand with a diameter of 0.5-0.7 mm and 2 parts of modified sodium type silica sol. The above different diameter silicon carbide sand and modified sodium type silica sol are mixed uniformly by stirring and then dried to obtain the pretreated silicon carbide graded particles.

[0133] (2) Put in the auxiliary material

[0134] The following components are weighed by weight parts: 2 parts of compound antioxidant sintering aid (B4C), 0.2 parts of rheological modifier (sodium tripolyphosphate), 0.2 parts of retarder (citric acid), 0.5 parts of anti-explosive agent (polypropylene fiber) and 5 parts of water.

[0135] (3) Mix the main material and the auxiliary material, and place them in a mold to form a green body.

[0136] (4) brushing an anti-oxidation coating layer with a thickness of about 2 mm on the green body, the anti-oxidation coating layer comprising mullite micro powder, andalusite micro powder and modified sodium type silica sol, and the weight ratio being 4:1:5. After brushing the anti-oxidation coating layer, low-temperature sintering is performed, starting from room temperature and heating to 160℃ at a heating rate of 30℃ / h~40℃ / h, and after reaching 160℃, keeping the temperature for 4 h, and then continuing to heat to 750℃ at a heating rate of 30℃ / h~40℃ / h, keeping the temperature for 4 h, and naturally cooling to room temperature, to obtain the silicon carbide ceramic composite material doped with steel fibers.

[0137] Figure 12 EDS spectrum of the composite material of the present embodiment is shown, combined with the EDS spectrum analysis result below:

[0138]

[0139] The chemical composition of the composite material of the present embodiment is C 23.81 O 45.30 Al 9.83 Si 20.29 Ca 0.77 .

[0140] Figure 13 The SEM photo shows that the composite material of the present embodiment has a pore structure, and the radial size (diameter) of the pore structure is about 1 μm~10 μm.

[0141] Example 4

[0142] The preparation method of the silicon carbide ceramic composite material of the present embodiment comprises the following steps (1)~(4).

[0143] (1) adding main materials

[0144] The following components are weighed by weight parts: 75 parts of pretreated silicon carbide graded particles, 10 parts of 200 mesh silicon carbide fine powder, 10 parts of calcium aluminate cement, 10 parts of aluminum oxide micro powder, 10 parts of silicon dioxide micro powder and 5 parts of steel fiber.

[0145] Among them, the pretreated silicon carbide graded particles comprise:

[0146] 15 parts of silicon carbide sand with a diameter of 3.35 mm~4.75 mm, 35 parts of silicon carbide sand with a diameter of 1.18 mm~2.8 mm, 22 parts of silicon carbide sand with a diameter of 0.5 mm~0.7 mm and 3 parts of modified sodium type silica sol. Among them, the above different diameter silicon carbide sand and modified sodium type silica sol are mixed uniformly by stirring and then dried to obtain the pretreated silicon carbide graded particles.

[0147] (2) adding auxiliary materials

[0148] The following components are weighed by weight parts: 3 parts of compounded antioxidant sintering aid (B4C and Al powder, mass ratio 1:1), 0.3 parts of rheological modifier (sodium tripolyphosphate), 0.3 parts of retarder (citric acid), 0.6 parts of anti-explosive agent (polypropylene fiber) and 6.5 parts of water.

[0149] (3) The main material and the auxiliary material are mixed and placed in a mold to form a green body.

[0150] (4) An oxidation-resistant coating with a thickness of about 1 mm is brushed on the green body, and the oxidation-resistant coating includes mullite powder, andalusite powder and modified sodium type silica sol, with a weight ratio of 4:1:5. After brushing the oxidation-resistant coating, low-temperature sintering is carried out, starting from room temperature to 150°C at a heating rate of 30°C / h~40°C / h, and after reaching 150°C, the temperature is kept for 5h, and then the temperature is continuously increased to 700°C at a heating rate of 30°C / h~40°C / h, and kept for 5h, and then naturally cooled to room temperature, to obtain a silicon carbide ceramic composite material doped with steel fibers.

[0151] Figure 14 The EDS spectrum of the composite material of the present embodiment is shown, combined with the EDS spectrum analysis result below:

[0152]

[0153] The chemical composition of the composite material of the present embodiment is C 15.11 O 53.92 Al 15.36 Si 13.20 Ca 1.88 Na 0.53 .

[0154] Figure 15 The SEM photo shows that the composite material of the present embodiment has a pore structure and includes lamellar particles.

[0155] Example 5

[0156] The preparation method of the silicon carbide ceramic composite material of the present embodiment includes the following steps (1)~(4).

[0157] (1) Put in the main material

[0158] The following components are weighed by weight parts: 70 parts of pretreated silicon carbide graded particles, 10 parts of 200 mesh silicon carbide fine powder, 8 parts of calcium aluminate cement, 2 parts of aluminum oxide micro powder, 2 parts of silicon dioxide micro powder and 0.5 parts of steel fiber.

[0159] The pretreated silicon carbide graded particles include:

[0160] 14 parts of silicon carbide sand with a diameter of 3.35mm~4.75mm, 35 parts of silicon carbide sand with a diameter of 1.18mm~2.8mm, 18 parts of silicon carbide sand with a diameter of 0.5mm~0.7mm and 3 parts of modified sodium type silica sol. Wherein, the above different diameter silicon carbide sand and modified sodium type silica sol are mixed uniformly by stirring and then dried to obtain the pretreated silicon carbide graded particles.

[0161] (2) Put in auxiliary materials

[0162] The following components are weighed by weight parts: 0.5 parts of compounded antioxidant sintering aid (B4C and Al powder, mass ratio is 1:1), 0.1 parts of rheological modifier (sodium tripolyphosphate), 0.01 parts of coagulant (lithium carbonate), 0.2 parts of anti-explosive agent (polypropylene fiber) and 4.5 parts of water.

[0163] (3) Mix the main materials and the auxiliary materials, and place them in the mold to form a green body.

[0164] (4) Brush a roughly 1mm thick anti-oxidation coating on the green body, the anti-oxidation coating includes mullite powder, microcline powder and modified sodium type silica sol, the weight ratio is 4:1:5. After brushing the anti-oxidation coating, low temperature sintering is carried out, starting from room temperature and heating to 150℃ at a heating rate of 30℃ / h~40℃ / h, after reaching 150℃, keeping for 5h, then continuing to heat to 650℃ at a heating rate of 30℃ / h~40℃ / h, keeping for 5h, and naturally cooling to room temperature, to obtain the silicon carbide ceramic composite material doped with steel fibers.

[0165] Figure 16 The EDS spectrum of the composite material of the present embodiment is shown, combined with the EDS spectrum analysis result below:

[0166]

[0167] The chemical composition of the composite material of the present embodiment is C 17.62 O 53.06 Al 15.37 Si 11.77 Ca 1.54 Na 0.64 .

[0168] Example 6

[0169] The preparation method of the silicon carbide ceramic composite material of the present embodiment includes the following steps (1)~(4).

[0170] (1) Put in main materials

[0171] The following components are weighed by weight parts: 57 parts of pre-processed silicon carbide graded particles, 10 parts of 200 mesh silicon carbide fine powder, 9 parts of calcium aluminate cement, 8 parts of aluminum oxide micro powder, 7 parts of silicon dioxide micro powder and 4 parts of steel fiber.

[0172] The pre-processed silicon carbide graded particles include:

[0173] 12 parts of silicon carbide sand with a diameter of 3.35mm~4.75mm, 27 parts of silicon carbide sand with a diameter of 1.18mm~2.8mm, 15 parts of silicon carbide sand with a diameter of 0.5mm~0.7mm and 3 parts of modified sodium type silica sol. The pre-processed silicon carbide graded particles are obtained by mixing the above-mentioned silicon carbide sand with different diameters and the modified sodium type silica sol uniformly through stirring and then drying.

[0174] (2) Put in the auxiliary materials

[0175] The following components are weighed by weight parts: 3 parts of compounded anti-oxidation sintering aid (B4C and Al powder, mass ratio 1:1), 0.2 parts of rheological modifier (sodium tripolyphosphate), 0.2 parts of retarder (citric acid), 0.5 parts of anti-explosive agent (polypropylene fiber) and 5 parts of water.

[0176] (3) Mix the main materials and the auxiliary materials, and place them in a mold to form a green body.

[0177] (4) Brush an anti-oxidation coating with a thickness of about 1mm on the green body, the anti-oxidation coating including mullite micro powder, andalusite micro powder and modified sodium type silica sol, with a weight ratio of 4:1:5. After brushing the anti-oxidation coating, low-temperature sintering is carried out, starting from room temperature and heating to 150℃ at a heating rate of 30℃ / h~40℃ / h, and after reaching 150℃, keeping the temperature for 5h, and then continuing to heat to 600℃ at a heating rate of 30℃ / h~40℃ / h, keeping the temperature for 5h, and naturally cooling to room temperature, to obtain the silicon carbide ceramic composite material doped with steel fiber.

[0178] Figure 17 The EDS spectrum of the composite material of the present embodiment is shown, and the EDS spectrum analysis result below is combined:

[0179]

[0180] The chemical composition of the composite material of the present embodiment is C 8.68 O 57.79 Al 17.85 Si 13.59 Ca 1.60 Na 0.50 .

[0181] Comparative Example 1

[0182] A method for preparing a silicon carbide ceramic composite material, which is different from example 1 in that the main material does not contain pre-processed silicon carbide graded particles, but only contains silicon carbide particles with a diameter of 1.18-2.8 mm in the pre-processed silicon carbide graded particles.

[0183] Comparative example 2

[0184] A method for preparing a silicon carbide ceramic composite material, which is different from example 1 in that the complex antioxidant sintering aid does not contain boron carbide, but only contains silicon powder and aluminum oxide with a mass ratio of 1:1.

[0185] Comparative example 3

[0186] A method for preparing a silicon carbide ceramic composite material, which is different from example 1 in that after forming the green body, the green body is not coated with an anti-oxidation coating and is directly subjected to low-temperature sintering.

[0187] Comparative example 4

[0188] A method for preparing a silicon carbide ceramic composite material, which is different from example 1 in that the green body is first subjected to low-temperature sintering, then brushed with an anti-oxidation coating, and baked at 200-300°C until dry.

[0189] The silicon carbide ceramic composite materials in examples 1-6 of the present application were tested for physical and chemical performance indicators, and the results are shown in Table 2.

[0190] Table 2: Physical and chemical performance indicators

[0191]

[0192] In Table 2, the tests of various properties simulate their usual use environment, for example, ceramic materials will be subjected to a radiation temperature of 800-1250°C. The detection standard for wear loss is GB / T18301, and the sample is tested for wear after being kept at 900°C for 3h. The cold bending strength is tested after the sample is kept at different temperatures (110-1350°C) for a certain time, for example, 110°C x 24h, i.e. the sample is kept at 110°C for 24h.

[0193] As can be seen from Table 2, the physical and chemical performance indicators of the silicon carbide ceramic composite material of the present application meet the requirements of the standard. Among them, the wear loss of the silicon carbide ceramic composite material is increased from ≤8cm 3 to ≤5cm 3The anti-bending strength is increased from the original ≥8MPa to ≥25MPa, and the average thermal expansion coefficient is increased from the original 0.47% to 0.4% at 20-750℃. The above-mentioned physical and chemical performance indexes of the composite materials in Comparative Examples 1-4 are all not as good as the example, so the above-mentioned performance of the low-temperature sintered silicon carbide ceramic composite material in the application is greatly and comprehensively improved.

[0194] It should be understood that the application is not limited to the details of the components and arrangement of the components set forth in the description. The application can have other embodiments and can be implemented and executed in various ways. The foregoing variations and modifications fall within the scope of the application. It should be understood that the application disclosed and defined in the specification extends to all alternative combinations of two or more of the individual features mentioned or evident from the description and / or drawings. All these different combinations constitute various alternative aspects of the application. The embodiments described in the specification illustrate the best way known to the inventors for carrying out the application and will enable others to adopt the application.

Claims

1. A silicon carbide ceramic composite sintered at a medium-low temperature with high thermal shock resistance, characterized in that, Its chemical composition includes C a O b Al c Si d Ca e Na f Wherein, a, b, c, d, e, f are the atomic content of the corresponding elements, 8.68≤a≤23.81, 45.30≤b≤57.79, 9.83≤c≤17.85, 13.20≤d≤20.29, 0.77≤e≤2.03, 0≤f≤0.64; the composite material exists pore structure and contains nano-sized particles, in the infrared spectrum, 1166cm -1 The shoulder peak shows the stretching vibration of Si-O, the strongest peak at 1091cm -1 The strongest peak at 1091cm -l The strongest peak at 1091cm -1 The strongest peak at 1091cm The temperature of the medium-low temperature sintering is not higher than 750 DEG C. The raw materials for preparing the composite material include main materials and auxiliary materials. The main materials include 55-75 parts by weight of pretreated silicon carbide graded particles, 10-12 parts by weight of 200-300 mesh silicon carbide powder, 2-10 parts by weight of calcium aluminate cement, 2-10 parts by weight of aluminum oxide powder, 2-10 parts by weight of silicon dioxide powder and 0.5-5 parts by weight of reinforcing materials; the reinforcing materials include at least one of steel fiber, silicon nitride whisker, silicon carbide whisker and aluminum oxide whisker. The pretreated silicon carbide graded particles include 12-15 parts by weight of silicon carbide sand with a diameter of 3.35-4.75 mm, 27-35 parts by weight of silicon carbide sand with a diameter of 1.18-2.8 mm, 15-22 parts by weight of silicon carbide sand with a diameter of 0.5-0.7 mm and 1-3 parts by weight of modified sodium type silica sol. The auxiliary materials include 0.5-3 parts by weight of compounded anti-oxidation sintering aid and 3-5 parts by weight of water; the compounded anti-oxidation sintering aid includes boron carbide powder.

2. The composite material of claim 1, wherein, The nano-sized particles are sheet-like particles with a size of 200-500 nm.

3. The composite material according to claim 1 or 2, characterized in that, The radial size of the hole-like structure is 1-10 microns.

4. The composite material according to claim 1 or 2, characterized in that, The composite material has a crystal structure.

5. The composite material according to claim 1 or 2, characterized in that, In the infrared spectrum, 480~650cm -1 The peaks in the range show the bending vibration modes of Si-O.

6. A method of producing a silicon carbide ceramic composite material sintered at a medium-low temperature with high thermal shock resistance according to any one of claims 1 to 5, characterized by, The method comprises the following steps: The main materials include 55-75 parts by weight of pretreated silicon carbide graded particles, 10-12 parts by weight of 200-300 mesh silicon carbide powder, 2-10 parts by weight of calcium aluminate cement, 2-10 parts by weight of aluminum oxide powder, 2-10 parts by weight of silicon dioxide powder and 0.5-5 parts by weight of reinforcing materials; the pretreated silicon carbide graded particles include silicon carbide sand with different particle sizes; The auxiliary materials include 0.5-3 parts by weight of compounded anti-oxidation sintering aid and 3-5 parts by weight of water; the compounded anti-oxidation sintering aid includes boron carbide powder; The main materials and the auxiliary materials are mixed and poured into a mold to form a green body; The surface of the green body is coated with an anti-oxidation coating, and the green body is subjected to medium-low temperature sintering at a temperature not higher than 750 DEG C. Before the main materials are poured, the method further comprises preparing the pretreated silicon carbide graded particles, which comprises the following steps: 12-15 parts by weight of silicon carbide sand with a diameter of 3.35-4.75 mm, 27-35 parts by weight of silicon carbide sand with a diameter of 1.18-2.8 mm, 15-22 parts by weight of silicon carbide sand with a diameter of 0.5-0.7 mm and 1-3 parts by weight of modified sodium type silica sol are obtained, and then mixed, stirred and dried to obtain the pretreated silicon carbide graded particles.

7. The method of claim 6, wherein, The green body coated with the anti-oxidation coating is subjected to medium-low temperature sintering, which comprises the following steps: The green body is heated from room temperature to a first preset temperature, and then kept at the first preset temperature for 4-6 hours, and then heated to a second preset temperature, and kept at the second preset temperature for 4-6 hours, and then naturally cooled to room temperature.

8. The method of claim 7, wherein The first preset temperature is 130°C to 160°C, and the heating rate from room temperature to the first preset temperature is 30°C / h to 40°C / h; The second preset temperature is 650° C. to 750° C., and a heating rate from the first preset temperature to the second preset temperature is 30° C. / h to 40° C. / h.

9. Use of the silicon carbide ceramic composite material according to any one of claims 1 to 5 and the silicon carbide ceramic composite material prepared by the method according to any one of claims 6 to 8 in a burner.

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