Multiphase ceramic material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of ceramic materials, and particularly relates to a composite ceramic material as well as a preparation method and application thereof. The composite ceramic material comprises a matrix and silicon carbide, the substrate coats silicon carbide, and the substrate comprises high-entropy carbide and high-entropy boride. According to the invention, through the design of components of the high-entropy material and the optimization of a preparation process, the composite ceramic material with a matrix being high-entropy carbide and high-entropy boride and SiC being a main second phase is obtained, the SiC is wrapped by the high-entropy carbide and the high-entropy boride in a dual-phase manner, the high-entropy carbide and the high-entropy boride are used in a combined manner, and the high-entropy material can be used for preparing the composite ceramic material. According to the present invention, the SiC particles are introduced into the ultra-high temperature ceramic, such that the mechanical property, the thermal stability and the chemical stability of the material can be improved, the toughening can be achieved by introducing the SiC particles into the ultra-high temperature ceramic, and the oxidation resistance and the ablation resistance of the material at the medium-high temperature can be effectively improved so as to provide the good mechanical property and the good ablation resistance of the ceramic material, and the certain wave absorbing property is hopeful.

Description

Technical Field

[0001] The present invention belongs to the technical field of ceramic materials, and in particular relates to a composite ceramic material and a preparation method and application thereof. Background Art

[0002] As the Mach number of high-speed aircraft continues to increase, the thermal barriers faced by thermal structures and thermal protection systems during service have become increasingly prominent. The surfaces of the aircraft's nose cone, leading edge, and scramjet engine combustion chamber and nozzle must withstand the aerodynamic heating effects of high heat flux and high dynamic pressure. Surface temperatures can reach over 2000°C in a short period of time, placing increasingly stringent demands on the thermal shock, high-temperature mechanical, and oxidation resistance properties of thermal structure and thermal protection materials.

[0003] Ultra-high temperature ceramics (UHTCs) are a class of specialized materials that maintain chemical stability at high temperatures (>2000°C) and in reactive atmospheres (such as oxidizing environments). These materials, primarily transition metal carbides, borides, and nitrides, are the preferred materials for thermal structures and thermal protection systems operating in extreme service environments. However, current ceramic materials still struggle with mechanical properties and oxidation and ablation resistance that meet these requirements.

[0004] Therefore, it is of great significance to provide a ceramic material with good mechanical properties and anti-oxidation and ablation properties. Summary of the Invention

[0005] The present invention aims to solve one or more technical problems existing in the above-mentioned prior art and at least provide a beneficial alternative. Specifically, the present invention provides a multiphase ceramic material having good mechanical properties and anti-oxidation and ablation properties.

[0006] The inventive concept of the present invention is as follows: The composite ceramic material of the present invention comprises a matrix and silicon carbide; the matrix coats the silicon carbide, and the matrix comprises high-entropy carbide and high-entropy boride. The combined use of high-entropy carbide and high-entropy boride of the present invention can improve the mechanical properties, thermal stability, and chemical stability of the material. By introducing SiC particles into ultrahigh-temperature ceramics, on the one hand, toughening mechanisms such as crack deflection, crack branching, and crack bridging can be activated, thereby achieving toughening. On the other hand, the glassy SiO2 phase formed during the oxidation and ablation process can effectively improve the material's oxidation resistance and ablation resistance at medium and high temperatures, resulting in the ceramic material having good mechanical properties and ablation resistance. Furthermore, ultrahigh-temperature ceramic carbides and borides both have high electrical conductivity and dielectric loss properties, and SiC has semiconductor properties and dielectric loss properties, making the prepared composite ceramic material potentially possessing certain microwave absorption properties.

[0007] Therefore, a first aspect of the present invention provides a composite ceramic material.

[0008] Specifically, the multiphase ceramic material includes a matrix and silicon carbide;

[0009] The substrate covers the silicon carbide, and the substrate includes high entropy carbide and high entropy boride.

[0010] Preferably, the molar ratio of the high entropy carbide, high entropy boride and SiC is (1.8-9):(1.8-9):(2.7-13).

[0011] Further preferably, the molar ratio of the high entropy carbide, high entropy boride and SiC is (2-8):(2-8):(3-12).

[0012] Preferably, the structural formula of the high entropy carbide is (M1 x1 M2 x2 ...Mn xn )C, the M1, M2, ...Mn are independently selected from any one of Ti, Zr, Hf, V, Nb, Ta, Mo, W, and Cr, and the M1, M2, ...Mn are different from each other, the sum of the x1, x2, ...xn is 1, and the n is ≥5.

[0013] Preferably, the structural formula of the high entropy boride is (M1 y1 M2 y2 ...Mn yn )B2, the M1, M2, ...Mn are independently selected from any one of Ti, Zr, Hf, V, Nb, Ta, Mo, W, Cr, and the M1, M2, ...Mn are different from each other, the sum of the y1, y2, ...yn is 1, and the n≥5.

[0014] Preferably, the M1, M2, ..., Mn are independently selected from any one of Ti, Zr, Hf, Nb and Ta, and the M1, M2, ..., Mn are different from each other.

[0015] Preferably, the x1, x2, ..., xn are equal or unequal, and the y1, y2, ..., yn are equal or unequal.

[0016] Specifically, rational composition and structural design are key to overcoming the inherent brittleness of ceramics and improving their oxidation resistance and ablation resistance. High-entropy ultrahigh-temperature ceramics combine the characteristics of ultrahigh-temperature ceramics and high-entropy materials, and are expected to have superior mechanical properties, thermal stability, and chemical stability compared to traditional single-component ultrahigh-temperature ceramics. High-entropy ultrahigh-temperature ceramics also offer advantages such as designable composition and controllable material properties.

[0017] The second aspect of the present invention provides a method for preparing the multiphase ceramic material described in the first aspect of the present invention.

[0018] Specifically, the method for preparing the composite ceramic material comprises the following steps:

[0019] (1) Carbide, B4C and Si are mixed and ground to obtain a mixture;

[0020] (2) placing the mixture obtained in step (1) in a mold, shaping it, and sintering it to obtain the composite ceramic material.

[0021] Preferably, in step (1), the carbides include at least five of TiC, ZrC, HfC, NbC, TaC, WC, Mo2C, VC and Cr3C2.

[0022] Further preferably, in step (1), the carbide includes TiC, ZrC, HfC, NbC and TaC.

[0023] Preferably, the molar ratio of the carbide, B4C and Si is 10:(0.9-4.5):(1.3-13).

[0024] Further preferably, the molar ratio of the carbide, B4C and Si is 10:(1-4):(1.5-12).

[0025] Preferably, the reaction equation during sintering is: 2TaC+2HfC+2NbC+2ZrC+2TiC+2.5B4C+xSi=5(Ta 0.2 Hf 0.2 Nb 0.2 Zr 0.2 Ti 0.2 )C+5(Ta 0.2 Hf 0.2 Nb 0.2 Zr 0.2 Ti 0.2 )B2+xSiC+(7.5-x)C.

[0026] Preferably, the value of x is 1.5-7.5; further preferably, the value of x can be selected from 7.5, 6, 4.5, 3 or 1.5.

[0027] Preferably, the reaction equation during sintering is: 2TaC+2HfC+2NbC+2ZrC+2TiC+0.5yB4C+1.5ySi=(10-y)(Ta 0.2 Hf 0.2 Nb 0.2 Zr 0.2 Ti 0.2 )C+y(Ta 0.2 Hf 0.2 Nb0.2 Zr 0.2 Ti 0.2 )B2+1.5ySiC.

[0028] Preferably, the value of y is 2-4; further preferably, the value of y can be selected from 2, 3 or 4.

[0029] Preferably, in step (1), the grinding includes ball milling, the grinding speed is 150-300 r / min, and the grinding time is 4-12 h.

[0030] Further preferably, in step (1), the grinding includes ball milling, the grinding speed is 180-250 r / min, and the grinding time is 5-8 h.

[0031] More preferably, in step (1), the grinding includes ball milling, the grinding speed is 200 r / min, and the grinding time is 6 h.

[0032] Preferably, the grinding process also includes a screening process.

[0033] Preferably, in step (2), the forming is dry pressing, and the pressure of the dry pressing is 4.5-22 MPa.

[0034] Further preferably, in step (2), the forming is dry pressing, and the pressure of the dry pressing is 5-20 MPa.

[0035] Preferably, the sintering temperature is 1600-2300° C., the uniaxial pressure of the sintering is 25-35 MPa, the holding time of the sintering is 0.5-2 h, and the holding time of the sintering is 0.5-2 h.

[0036] Further preferably, the sintering temperature is 1700-1900° C., the uniaxial pressure of the sintering is 27-33 MPa, the holding time of the sintering is 0.8-1.2 h, and the holding time of the sintering is 0.8-1.2 h.

[0037] More preferably, the sintering temperature is 1800° C., the uniaxial pressure of the sintering is 30 MPa, the holding time of the sintering is 1 hour, and the holding time of the sintering is 1 hour.

[0038] A third aspect of the present invention provides a flying device.

[0039] Specifically, the flight equipment includes the multiphase ceramic material described in the first aspect of the present invention.

[0040] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0041] The present invention obtains a multiphase ceramic material with a matrix of high-entropy carbide and high-entropy boride and SiC as the main second phase through the optimization of the design of high-entropy material components and the preparation process, wherein SiC is dual-phase wrapped by high-entropy carbide and high-entropy boride. The combined use of high-entropy carbide and high-entropy boride can improve the mechanical properties, thermal stability and chemical stability of the material. By introducing SiC particles into ultra-high temperature ceramics, on the one hand, toughening mechanisms such as crack deflection, crack branching and crack bridging can be activated, thereby achieving toughening; on the other hand, the glassy SiO2 phase formed during the oxidation and ablation process can effectively improve the material's oxidation resistance and ablation resistance at medium and high temperatures, so that the ceramic material has good mechanical properties and ablation resistance, and is expected to have certain wave absorption properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a process curve diagram of hot pressing sintering of the composite ceramic material according to Example 1 of the present invention;

[0043] Figure 2 X-ray diffraction patterns of the composite ceramic materials of Examples 1-4 of the present invention;

[0044] Figure 3 The microstructure and corresponding element distribution diagram of the composite ceramic material of Example 2 of the present invention;

[0045] Figure 4 Schematic diagram of crack deflection of the composite ceramic material of Example 2 under a load of 1 kgf and the composite ceramic material of Example 4 under a load of 5 kgf. DETAILED DESCRIPTION

[0046] In order to make the technical solution of the present invention more clearly understood by those skilled in the art, the following examples are given for illustration. It should be noted that the following examples do not limit the scope of protection claimed by the present invention.

[0047] Unless otherwise specified, the raw materials, reagents, or devices used in the following examples can be obtained from conventional commercial sources or by existing known methods.

[0048] Example 1

[0049] A composite ceramic material comprising high entropy carbide, high entropy boride and silicon carbide; high entropy carbide and high entropy boride coated silicon carbide;

[0050] The molar ratio of high entropy carbide, high entropy boride and silicon carbide is 5:5:6;

[0051] The structural formulas of high entropy carbide and high entropy boride are (Ta 0.2 Hf 0.2 Nb 0.2 Zr0.2 Ti 0.2 )C and (Ta 0.2 Hf 0.2 Nb 0.2 Zr 0.2 Ti 0.2 )B2.

[0052] A method for preparing a composite ceramic material comprises the following steps:

[0053] (1) Ultra-high temperature ceramic carbide raw materials were weighed according to a molar ratio of TiC:ZrC:HfC:NbC:TaC = 1:1:1:1:1, and then weighed according to a molar ratio of carbide:B4C:Si = 10:2.5:6. The purity of all raw materials was 99-99.99%;

[0054] (2) Wet-mixing the above raw materials in a ball mill using anhydrous ethanol as the medium, a ball milling jar and grinding balls made of zirconia, a rotation speed of 200 r / min, and a time of 6 h. After mixing, drying and passing through a 60-mesh sieve to obtain a mixed raw material;

[0055] (3) placing the mixed raw material obtained in step (2) in a graphite mold with an inner diameter of φ = 30 mm, and performing unidirectional pressure molding on a dry press at a molding pressure of 20 MPa to obtain a ceramic green body;

[0056] (4) The ceramic body formed by dry pressing in step (3) is placed together with the mold into a hot pressing furnace and hot pressed and sintered in a vacuum atmosphere at a sintering temperature of 1800°C, a uniaxial pressure of 30 MPa, and a holding time of 1 h to obtain a composite ceramic material.

[0057] During the hot pressing sintering process, the specific heating and pressurizing procedures are as follows:

[0058]

[0059] Finally, it is cooled in the furnace, and RT stands for room temperature.

[0060] Reaction formula:

[0061] 2TaC+2HfC+2NbC+2ZrC+2TiC+2.5B4C+6Si=5(Ta 0.2 Hf 0.2 Nb 0.2 Zr0.2Ti 0.2 )C+5(Ta 0.2 Hf 0.2 Nb 0.2 Zr0.2Ti 0.2 )B2+6SiC+1.5C.

[0062] The process curve of hot pressing sintering of Example 1 is as follows: Figure 1 shown.

[0063] The density of the composite ceramic material prepared in Example 1 was tested using the Archimedean drainage method. The density was 98.3%. The Vickers hardness was 23.1 GPa when the load was held for 15 s under a load of 1 kgf.

[0064] Example 2

[0065] A composite ceramic material comprising high entropy carbide, high entropy boride and silicon carbide; high entropy carbide and high entropy boride coated silicon carbide;

[0066] The molar ratio of high entropy carbide, high entropy boride and silicon carbide is 5:5:4.5;

[0067] The structural formulas of high entropy carbide and high entropy boride are (Ta 0.2 Hf 0.2 Nb 0.2 Zr 0.2 Ti 0.2 )C and (Ta 0.2 Hf 0.2 Nb 0.2 Zr 0.2 Ti 0.2 )B2.

[0068] A method for preparing a composite ceramic material comprises the following steps:

[0069] (1) Ultra-high temperature ceramic carbide raw materials were weighed according to a molar ratio of TiC:ZrC:HfC:NbC:TaC = 1:1:1:1:1, and then weighed according to a molar ratio of carbide:B4C:Si = 10:2.5:4.5. The purity of all raw materials was 99-99.99%;

[0070] (2) Wet-mixing the above raw materials in a ball mill using anhydrous ethanol as the medium, a ball milling jar and grinding balls made of zirconia, a rotation speed of 200 r / min, and a time of 6 h. After mixing, drying and passing through a 60-mesh sieve to obtain a mixed raw material;

[0071] (3) placing the mixed raw material obtained in step (2) in a graphite mold with an inner diameter of φ = 30 mm, and performing unidirectional pressure molding on a dry press at a molding pressure of 20 MPa to obtain a ceramic green body;

[0072] (4) The ceramic body formed by dry pressing in step (3) is placed together with the mold into a hot pressing furnace and hot pressed and sintered in a vacuum atmosphere at a sintering temperature of 1800°C, a uniaxial pressure of 30 MPa, and a holding time of 1 h to obtain a composite ceramic material.

[0073] During the hot pressing sintering process, the specific heating and pressurizing procedures are as follows:

[0074]

[0075] Finally, it is cooled in the furnace, and RT stands for room temperature.

[0076] Reaction formula:

[0077] 2TaC+2HfC+2NbC+2ZrC+2TiC+2.5B4C+4.5Si=5(Ta 0.2 Hf 0.2 Nb 0.2 Zr 0.2 Ti 0.2 )C+5(Ta 0.2 Hf 0.2 Nb 0.2 Zr 0.2 Ti 0.2 )B2+4.5SiC+3C.

[0078] The density of the composite ceramic material prepared in Example 1 was tested using the Archimedean drainage method, and the density was 99.9%.

[0079] Under a load of 1 kgf, the Vickers hardness when the load is maintained for 15 seconds is 21.9 GPa.

[0080] In addition, the three-point bending method was used to test the bending strength, and the beam loading speed was 0.5mm / min. The SENB method was used to perform the fracture toughness test using three-point bending, and the loading speed was 0.05mm / min. The electromagnetic parameters were obtained through the waveguide method, and the minimum reflection loss was calculated.

[0081] After testing, the bending strength of the sample was 725.6±23.3MPa, the fracture toughness was 6.9±0.6, and when the sample thickness was 1.85mm, the minimum reflection loss value reached -53.57dB (15.81GHz).

[0082] Example 3

[0083] A composite ceramic material comprising high entropy carbide, high entropy boride and silicon carbide; high entropy carbide and high entropy boride coated silicon carbide;

[0084] The molar ratio of high entropy carbide, high entropy boride and silicon carbide is 7:3:4.5;

[0085] The structural formulas of high entropy carbide and high entropy boride are (Ta 0.2 Hf 0.2 Nb 0.2 Zr 0.2Ti 0.2 )C and (Ta 0.2 Hf 0.2 Nb 0.2 Zr 0.2 Ti 0.2 )B2.

[0086] A method for preparing a composite ceramic material comprises the following steps:

[0087] (1) Ultra-high temperature ceramic carbide raw materials were weighed according to a molar ratio of TiC:ZrC:HfC:NbC:TaC = 1:1:1:1:1, and then weighed according to a molar ratio of carbide:B4C:Si = 10:1.5:4.5. The purity of all raw materials was 99-99.99%;

[0088] (2) Wet-mixing the above raw materials in a ball mill using anhydrous ethanol as the medium, a ball milling jar and grinding balls made of zirconia, a rotation speed of 200 r / min, and a time of 6 h. After mixing, drying and passing through a 60-mesh sieve to obtain a mixed raw material;

[0089] (3) placing the mixed raw material obtained in step (2) in a graphite mold with an inner diameter of φ = 30 mm, and performing unidirectional pressure molding on a dry press at a molding pressure of 20 MPa to obtain a ceramic green body;

[0090] (4) The ceramic body formed by dry pressing in step (3) is placed together with the mold into a hot pressing furnace and hot pressed and sintered in a vacuum atmosphere at a sintering temperature of 1800°C, a uniaxial pressure of 30 MPa, and a holding time of 1 h to obtain a composite ceramic material.

[0091] During the hot pressing sintering process, the specific heating and pressurizing procedures are as follows:

[0092]

[0093] Finally, it is cooled in the furnace, and RT stands for room temperature.

[0094] Reaction formula:

[0095] 2TaC+2HfC+2NbC+2ZrC+2TiC+1.5B4C+4.5Si=7(Ta 0.2 Hf 0.2 Nb 0.2 Zr 0.2 Ti 0.2 )C+3(Ta 0.2 Hf 0.2 Nb 0.2 Zr 0.2 Ti 0.2 )B2+4.5SiC.

[0096] The density of the composite ceramic material prepared in Example 1 was tested using the Archimedean drainage method. The density was 97.9%. The Vickers hardness was 23.3 GPa when the load was held for 15 s under a load of 1 kgf.

[0097] Example 4

[0098] A composite ceramic material comprising high entropy carbide, high entropy boride and silicon carbide; high entropy carbide and high entropy boride coated silicon carbide;

[0099] The molar ratio of high entropy carbide, high entropy boride and silicon carbide is 6:4:6;

[0100] The structural formulas of high entropy carbide and high entropy boride are (Ta 0.2 Hf 0.2 Nb 0.2 Zr 0.2 Ti 0.2 )C and (Ta 0.2 Hf 0.2 Nb 0.2 Zr 0.2 Ti 0.2 )B2.

[0101] A method for preparing a composite ceramic material comprises the following steps:

[0102] (1) Ultra-high temperature ceramic carbide raw materials were weighed according to a molar ratio of TiC:ZrC:HfC:NbC:TaC = 1:1:1:1:1, and then weighed according to a molar ratio of carbide:B4C:Si = 10:2:6. The purity of all raw materials was 99-99.99%;

[0103] (2) Wet-mixing the above raw materials in a ball mill using anhydrous ethanol as the medium, a ball milling jar and grinding balls made of zirconia, a rotation speed of 200 r / min, and a time of 6 h. After mixing, drying and passing through a 60-mesh sieve to obtain a mixed raw material;

[0104] (3) placing the mixed raw material obtained in step (2) in a graphite mold with an inner diameter of φ = 30 mm, and performing unidirectional pressure molding on a dry press at a molding pressure of 20 MPa to obtain a ceramic green body;

[0105] (4) The ceramic body formed by dry pressing in step (3) is placed together with the mold into a hot pressing furnace and hot pressed and sintered in a vacuum atmosphere at a sintering temperature of 1800°C, a uniaxial pressure of 30 MPa, and a holding time of 1 h to obtain a composite ceramic material.

[0106] During the hot pressing sintering process, the specific heating and pressurizing procedures are as follows:

[0107]

[0108] Finally, it is cooled in the furnace, and RT stands for room temperature.

[0109] Reaction formula:

[0110] 2TaC+2HfC+2NbC+2ZrC+2TiC+1.5B4C+4.5Si=7(Ta 0.2 Hf 0.2 Nb 0.2 Zr 0.2 Ti 0.2 )C+3(Ta 0.2 Hf 0.2 Nb 0.2 Zr 0.2 Ti 0.2 )B2+4.5SiC.

[0111] The density of the composite ceramic material prepared in Example 1 was tested using the Archimedean drainage method, and the density was 99.7%.

[0112] Under a load of 5 kgf, the Vickers hardness when the load is maintained for 15 seconds is 22.1 GPa.

[0113] The ceramic sample was ablated using an oxyacetylene flame. The pressure and flow rates of acetylene and oxygen were 0.10 MPa and 0.40 MPa and 1116 L / h and 1512 L / h, respectively. The distance between the sample and the nozzle was 10 mm. The ablation time was 40 s. The linear ablation rate of the sample was 7.535 μm / s, and the mass ablation rate was 5.08 mg / s.

[0114] Among them, the calculation method of line ablation rate is: R d =(d1-d2) / t, d1 and d2 are the original thickness and thickness after ablation of the sample, respectively, and t is the ablation time;

[0115] The calculation method of mass ablation rate is: R m =(m1-m2) / t, m1 and m2 are the original mass and mass after ablation of the sample respectively, and t is the ablation time.

[0116] Example 5

[0117] A composite ceramic material comprising high entropy carbide, high entropy boride and silicon carbide; high entropy carbide and high entropy boride coated silicon carbide;

[0118] The molar ratio of high entropy carbide, high entropy boride and silicon carbide is 5:5:1.5;

[0119] The structural formulas of high entropy carbide and high entropy boride are (Ta 0.2 Hf0.2 Nb 0.2 Zr 0.2 Ti 0.2 )C and (Ta 0.2 Hf 0.2 Nb 0.2 Zr 0.2 Ti 0.2 )B2.

[0120] A method for preparing a composite ceramic material comprises the following steps:

[0121] (1) Ultrahigh temperature ceramic carbide raw materials were weighed according to a molar ratio of TiC:ZrC:HfC:NbC:TaC = 1:1:1:1:1, and then weighed according to a molar ratio of carbide:B4C:Si = 10:2.5:1.5. The purity of all raw materials was 99-99.99%;

[0122] (2) Wet-mixing the above raw materials in a ball mill using anhydrous ethanol as the medium, a ball milling jar and grinding balls made of zirconia, a rotation speed of 200 r / min, and a time of 6 h. After mixing, drying and passing through a 60-mesh sieve to obtain a mixed raw material;

[0123] (3) placing the mixed raw material obtained in step (2) in a graphite mold with an inner diameter of φ = 30 mm, and performing unidirectional pressure molding on a dry press at a molding pressure of 20 MPa to obtain a ceramic green body;

[0124] (4) The ceramic body formed by dry pressing in step (3) is placed together with the mold into a hot pressing furnace and hot pressed and sintered in a vacuum atmosphere at a sintering temperature of 1800°C, a uniaxial pressure of 30 MPa, and a holding time of 1 h to obtain a composite ceramic material.

[0125] During the hot pressing sintering process, the specific heating and pressurizing procedures are as follows:

[0126]

[0127] Finally, it is cooled in the furnace, and RT stands for room temperature.

[0128] Reaction formula:

[0129] 2TaC+2HfC+2NbC+2ZrC+2TiC+2.5B4C+1.5Si=5(Ta 0.2 Hf 0.2 Nb 0.2 Zr 0.2 Ti 0.2 )C+5(Ta 0.2 Hf 0.2 Nb 0.2 Zr 0.2 Ti0.2 )B2+1.5SiC+6C.

[0130] The density of the composite ceramic material prepared in Example 1 was tested using the Archimedean drainage method, and the density was 99.8%.

[0131] When the thickness of the sample is 1.80 mm, the minimum reflection loss value reaches -48.05 dB (15.57 GHz). The calculation method of the minimum reflection loss value is the same as the calculation method in Example 2.

[0132] Performance Testing

[0133] 1. X-ray diffraction test

[0134] The composite ceramic materials prepared in Examples 1-4 were subjected to X-ray diffraction tests, and the results were as follows: Figure 2 As shown. Figure 2 It can be seen that the composite ceramic material prepared in the present invention contains carbide, boride and silicon carbide.

[0135] 2. Scanning Electron Microscope Analysis

[0136] The composite ceramic material prepared in Example 2 was tested by scanning electron microscopy, and the microstructure and element distribution results are shown in FIG. Figure 3 As shown, Figure 3 Figure (a) shows the microstructure of the composite ceramic material, where HEB represents boride and HEC represents carbide. Figure 3 Figures (b)-(j) are the element distribution diagrams of C, O, Si, Ti, Zr, Nb, Hf, Ta, and B, respectively. The scales of Figures (b)-(i) are the same as those of Figure (j).

[0137] Depend on Figure 3 It can be seen that the composite ceramic material of Example 2 is mainly composed of a high entropy carbide and high entropy boride dual-phase high entropy ultra-high temperature ceramic matrix and a SiC second phase, wherein the SiC is wrapped by the high entropy carbide and high entropy boride dual phases.

[0138] 3. Crack deflection analysis

[0139] The crack deflection of the sample of Example 2 under a load of 1 kgf (Vickers hardness tester) and the sample of Example 4 under a load of 5 kgf (Vickers hardness tester) were analyzed using a scanning electron microscope. The results are as follows: Figure 4 As shown. Among them, Figure 4 Figure (a) is a schematic diagram of crack deflection of the sample of Example 2 under a load of 1 kgf. Figure 4 Figure (b) is an enlarged view of the box in Figure (a). Figure 4 Figure (c) is a schematic diagram of crack deflection of the sample of Example 4 under a load of 5 kgf. Figure 4Figure (d) is an enlarged view of the box in Figure (c); Figure 4 In Figures (b) and (d), HEB represents boride and HEC represents carbide.

[0140] Depend on Figure 4 It can be seen that during the crack expansion process at the four corners of the indentation, the cracks do not expand in a straight line, but deflect, which is beneficial to the improvement of the fracture toughness of the material.

[0141] In summary, the present invention obtains a multiphase ceramic material with a matrix of high-entropy carbide and high-entropy boride and SiC as the main second phase through the optimization of the design of high-entropy material components and the preparation process, and SiC is wrapped by a dual phase of high-entropy carbide and high-entropy boride, which can make the ceramic material have good mechanical properties and ablation resistance, and is expected to have certain wave absorption properties.

[0142] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A composite ceramic material, characterized in that: including a substrate and silicon carbide; The substrate covers the silicon carbide, and the substrate includes high entropy carbide and high entropy boride.

2. The composite ceramic material according to claim 1, characterized in that: The molar ratio of the high entropy carbide, high entropy boride and SiC is (1.8-9): (1.8-9): (2.7-13).

3. The multiphase ceramic material according to claim 1, characterized in that: The structural formula of the high entropy carbide is (M1 x1 M2 x2 ...Mn xn )C, the M1, M2, ...Mn are independently selected from any one of Ti, Zr, Hf, V, Nb, Ta, Mo, W, and Cr, and the M1, M2, ...Mn are different from each other, the sum of the x1, x2, ...xn is 1, and the n is ≥5.

4. The multiphase ceramic material according to claim 1, characterized in that: The structural formula of the high entropy boride is (M1 y1 M2 y2 ...Mn yn )B2, the M1, M2, ...Mn are independently selected from any one of Ti, Zr, Hf, V, Nb, Ta, Mo, W, Cr, and the M1, M2, ...Mn are different from each other, the sum of the y1, y2, ...yn is 1, and the n≥5.

5. The method for preparing the composite ceramic material according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) Carbide, B4C and Si are mixed and ground to obtain a mixture; (2) placing the mixture obtained in step (1) in a mold, shaping it, and sintering it to obtain the composite ceramic material.

6. The preparation method according to claim 5, characterized in that In step (1), the carbides include at least five of TiC, ZrC, HfC, NbC, TaC, WC, Mo2C, VC and Cr3C2.

7. The preparation method according to claim 5, characterized in that In step (1), the molar ratio of the carbide, B4C and Si is 10:(0.9-4.5):(1.3-13).

8. The preparation method according to claim 5, characterized in that In step (1), the grinding includes ball milling, the grinding speed is 150-300 r / min, and the grinding time is 4-12 h.

9. The preparation method according to claim 5, characterized in that In step (2), the forming is dry pressing, and the pressure of the dry pressing is 4.5-22 MPa; and / or the sintering temperature is 1600-2300°C, the uniaxial pressure of the sintering is 25-35 MPa, the holding time of the sintering is 0.5-2h, and the holding time of the sintering is 0.5-2h.

10. A flying device, characterized in that: The composite ceramic material comprises the composite ceramic material according to any one of claims 1 to 4.

Images