High-temperature-resistant high-entropy mullite ceramic, preparation method and application thereof

Abstract

The application discloses a high-temperature-resistant high-entropy mullite ceramic and a preparation method and application thereof, belongs to the technical field of surface coating, and discloses the chemical composition of the high-temperature-resistant high-entropy mullite ceramic and the mass fraction thereof, and on the basis, the preparation method of the high-temperature-resistant high-entropy mullite ceramic and the method for applying the prepared high-temperature-resistant high-entropy mullite ceramic to preparing a metal oxidation-resistant coating are disclosed, which comprises the following steps: S1, weighing and ball-milling mixing of raw materials; S2, drying of the mixed materials; S3, pressing forming; S4, sintering of the high-entropy mullite ceramic blank; S5, preparation of a slurry; S7, coating; and S8, sintering of the coating. Compared with pure high-entropy mullite, the prepared product is easy to obtain, the coating process is simple and fast, the high-temperature-resistant high-entropy mullite ceramic has good combination with the metal substrate as the oxidation-resistant coating, and the oxidation resistance and wear resistance of the metal surface are improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of surface coating, and particularly relates to a high-temperature-resistant high-entropy mullite ceramic as well as a preparation method and application thereof. BACKGROUND

[0002] Alloys are widely used in various fields such as construction, chemical industry, military industry and electronic communication due to their high strength, good toughness and strong forming processability. However, most alloys have poor oxidation resistance, which seriously affects their service life. In recent years, many scholars have used various methods to treat the surface of alloys to solve this problem. Among them, the use of ceramic coating on the surface of alloys has made great progress. Ceramics not only have natural oxidation resistance, but also have a great influence on the improvement of the mechanical properties of alloys.

[0003] High-entropy ceramic coatings are widely used in thermal barrier coating materials due to their high-entropy effect in thermodynamics, slow diffusion effect in kinetics, lattice distortion effect in structure and "cocktail" effect in performance, mainly including high-entropy fluorite, spinel, perovskite and pyrochlore. Mullite ceramic is a high-quality high-temperature-resistant material with the advantages of high-temperature resistance, high strength and small thermal conductivity. At the same time, the preparation process of mullite coating is simple, mature and low in cost.

[0004] There are records about the preparation technology and practical application of high-entropy ceramic coatings in Chinese patent documents. For example, Chinese patent CN111254379A prepared a five-element high-entropy carbide or nitride ceramic and used a thermal spraying method to spray it onto the surface of a metal substrate to prepare a coating material with excellent performance. However, the thermal spraying method is high in cost, and the metal needs to be sandblasted, which makes the coating process complex. Chinese patent CN106435443A prepared a Si powder-mullite powder-Yb2SiO5 powder three-layer composite coating on a silicon-based composite material to improve the oxidation resistance of the silicon-based composite material. The disadvantage is that the coating preparation process is complex and needs to be prepared by three times of plasma spraying. Chinese patent CN104697918A prepared a CrTiAlN coating on M2 high-speed steel by magnetron sputtering, and then conducted an oxidation resistance test at 500-700 DEG C for 1 h. The oxidation result is acceptable, but the CrTiAlN coating itself is easy to be oxidized, which limits the oxidation resistance temperature.

[0005] In summary, the current high-entropy ceramic coating mainly improves the oxidation resistance, wear resistance and corrosion resistance of metals. The method of combining ceramic coating with metal substrate is mainly thermal spraying, which is relatively complex. SUMMARY

[0006] In order to solve the above prior art deficiencies, the purpose of the present application aims to provide a high-temperature-resistant high-entropy mullite ceramic and a preparation method and application thereof.

[0007] The design concept of the present application is that: taking alumina, silicon dioxide, magnesium oxide, chromium sesquioxide, zirconium oxychloride and titanium dioxide as raw materials, a relatively pure high-entropy mullite ceramic is prepared by a solid-phase sintering method, which is then used as a coating raw material, and a slurry coating method is used to coat the surface of a metal substrate, followed by an oxidation resistance experiment. The slurry coating process is simple and convenient compared to other coating processes, and has no special requirements for the shape and surface of the metal substrate, the coating and the substrate material have good combination, and the oxidation resistance temperature is high.

[0008] The present application is realized by the following technical scheme: a high-temperature-resistant high-entropy mullite ceramic, the chemical composition and mass fraction thereof are: 30-60 parts of alumina, 10-30 parts of silicon dioxide, 1-5 parts of magnesium oxide, 2-10 parts of titanium dioxide, 5-20 parts of chromium sesquioxide, and 10-30 parts of zirconium oxychloride, and the ratio of the total mass of alumina and silicon dioxide to the total mass of the other four oxides is (1.5-3):(0.5-2).

[0009] Further, the raw materials of the high-temperature-resistant high-entropy mullite ceramic are all in the form of powder, and the particle size of the powder is 1-100 microns.

[0010] A preparation method of the high-temperature-resistant high-entropy mullite ceramic as described above, comprising the following steps:

[0011] S1, first, the raw materials are weighed according to the chemical composition and mass fraction of the high-temperature-resistant high-entropy mullite ceramic; then, the weighed high-temperature-resistant high-entropy mullite ceramic raw materials and 10-50 mL of alcohol are added to a ball mill, the ball milling time is set to 5-20 h, the ball milling speed is 100-500 rpm, the ball mill is started to mix the high-temperature-resistant high-entropy mullite ceramic raw materials uniformly, and the prepared mixture is prepared for use;

[0012] S2, the mixture prepared in step S1 is dried, the drying temperature is 50-150 DEG C, and the drying time is 1-10 h;

[0013] S3, 0.5-2 g of the material dried in step S2 is weighed and pressed into a shape, the pressure is 5-30 MPa, and the pressure holding time is 5-10 min, and a block-shaped blank is prepared;

[0014] S4, the block-shaped blank prepared in step S3 is sintered, the sintering temperature is 1500-1800 DEG C, and a high-temperature-resistant high-entropy mullite ceramic blank is prepared.

[0015] Further, in the step S4, the temperature mechanism of the blank sintering is:

[0016] First stage: 0-1000℃, heating rate is 3-10℃ / min;

[0017] Second stage: 1000-1400℃, heating rate is 1-5℃ / min;

[0018] Third stage: 1400℃, holding for 30min-3h;

[0019] Fourth stage: 1400-1800℃, heating rate is 1-5℃ / min, holding for 30min-3h;

[0020] Cooling stage: natural cooling to room temperature.

[0021] The application of a high-temperature-resistant high-entropy mullite ceramic blank prepared by the preparation method as described above in the preparation of an oxidation-resistant coating on a metal surface. The method for preparing the oxidation-resistant coating on the metal surface by using the high-temperature-resistant high-entropy mullite ceramic blank comprises the following steps:

[0022] S1, grinding the high-entropy mullite blank to below 200 mesh to obtain a high-entropy mullite powder;

[0023] S2, first, the raw materials are weighed according to the chemical composition and mass fraction of the slurry: 30-70 parts of the high-entropy mullite powder prepared in step S1, 10-50 parts of lead tetroxide powder, 10-50 parts of copper oxide powder, and 1-5 parts of zinc oxide powder; then, 2-7 drops of a binder are added dropwise into the slurry raw materials as a solvent, and the high-entropy mullite slurry is prepared after sufficient stirring;

[0024] S3, placing the polished metal block into the high-entropy mullite slurry prepared in step S2, taking it out after the slurry is evenly wrapped, and then drying, and then performing coating sintering, the sintering temperature is 300-600℃, and the holding time is 1-5h, to obtain an oxidation-resistant coating on the surface of the metal block.

[0025] Further, in the step S2, the binder is a sodium silicate aqueous solution, the slurry raw materials are all in the form of powder, and the particle size of the powder is 1-100 microns.

[0026] Further, in the step S3, the temperature mechanism of the coating sintering is:

[0027] First stage: 0-100℃, heating rate is 2-6℃ / min, holding time is 10min-3h;

[0028] Second stage: 100-300℃, heating rate is 2-6℃ / min, holding time is 1-3h;

[0029] The third stage: 300-600 DEG C, the temperature rising rate is 5-15 DEG C / min, and the holding time is 1-5h;

[0030] The cooling stage: natural cooling to room temperature.

[0031] The beneficial effects of the present application are that:

[0032] The present application adopts the solid phase sintering method to prepare high-entropy mullite ceramic as the coating raw material, and then adopts the slurry coating method to coat the coating on the surface of the metal substrate, compared with the thermal spraying method, which is simpler, not only improves the metal oxidation resistance and wear resistance, but also has better bonding force with the metal substrate, effectively improves the metal oxidation resistance. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 The preparation process flow chart of the present application is shown in the figure;

[0034] Figure 2 The temperature mechanism process curve figure of high-entropy mullite blank sintering is shown in the figure;

[0035] Figure 3 The temperature mechanism process curve figure of coating sintering is shown in the figure;

[0036] Figure 4 The XRD figure of high-entropy mullite blank prepared in example 3 is shown in the figure;

[0037] Figure 5 The mass difference contrast figure of the coating of the present application before and after oxidation corresponding to different Pb3O4 addition amounts is shown in the figure;

[0038] Figure 6 The contrast figure of pure mullite coating and high-entropy mullite coating after 1h oxidation at 700 DEG C and 800 DEG C is shown in the figure; Figure 6 Among them, (a) is the real photo of pure mullite coating after 1h oxidation at 700 DEG C, (b) is the real photo of pure mullite coating after 1h oxidation at 800 DEG C, (c) is the real photo of high-entropy mullite coating after 1h oxidation at 700 DEG C, and (d) is the real photo of high-entropy mullite coating after 1h oxidation at 800 DEG C. DETAILED DESCRIPTION

[0039] The present application will be further described in detail below in combination with the drawings and examples, but the protection scope of the present application is not limited to the following description.

[0040] Before the experiment, alumina, silicon dioxide, chromium sesquioxide, zirconium oxychloride, zirconium dioxide, titanium dioxide, magnesium oxide, lead trioxide, zinc oxide, copper oxide, and pure mullite are ground into powder for use. The above raw materials are commercially available and the particle size is below 20 microns. Example 1

[0041] A high-temperature-resistant high-entropy mullite ceramic, the chemical composition and mass fraction of which are: Al2O3: 1.5g, SiO2: 0.5g, TiO2: 0.2g, Cr2O3: 0.39g, MgO: 0.1g, ZrO2: 0.31g, and MgO, ZrO2, TiO2, and Cr2O3 are in equimolar ratio.

[0042] A preparation method of the high-temperature-resistant high-entropy mullite ceramic as described above, comprising the following steps:

[0043] S1, first, raw materials are weighed according to the chemical composition and mass fraction of the high-temperature-resistant high-entropy mullite ceramic; then, the weighed high-temperature-resistant high-entropy mullite ceramic raw materials are poured into a ball mill tank, 28mL of alcohol is added, the ball milling time is set to 9h, the ball milling speed is 300r / min, the ball mill is started to uniformly mix the high-temperature-resistant high-entropy mullite ceramic raw materials, and the prepared mixture is reserved;

[0044] S2, the mixture prepared in step S1 is subjected to drying treatment in an oven, the drying temperature is 80℃, and the drying time is 6h;

[0045] S3, the dried material in step S2 is weighed and placed in a tablet press mold for compression molding, the pressure is 20MPa, and the pressure holding time is 10min, and a block-shaped blank is prepared;

[0046] S4, the block-shaped blank prepared in step S3 is placed in a muffle furnace for blank sintering, and the temperature mechanism of the blank sintering is:

[0047] First stage: 0-1000℃, the heating rate is 5℃ / min;

[0048] Second stage: 1000-1400℃, the heating rate is 3℃ / min;

[0049] Third stage: 1400℃ for 1h, for promoting the formation of mullite;

[0050] Fourth stage: 1400-1600℃, the heating rate is 2℃ / min, and the holding time is 1h;

[0051] Cooling stage: naturally cooled to room temperature, and a high-entropy mullite blank is prepared.

[0052] The high-entropy mullite blank prepared in Example 1 is subjected to XRD test, and the results are: the mullite phase content is 69.7%, the remaining phases are 21.4% of chromium sesquioxide and aluminum sesquioxide and 8.9% of zirconium dioxide, and Rwp=7.3918%. Example 2

[0053] A high-temperature-resistant high-entropy mullite ceramic, the chemical composition and mass fraction of which are: Al2O3: 1.5 g, SiO2: 0.5 g, TiO2: 0.14 g, Cr2O3: 0.26 g, MgO: 0.07 g, ZrOCl2·8H2O: 0.53 g, and MgO, ZrOCl2·8H2O, TiO2, Cr2O3 are in equimolar ratio, that is, in this embodiment 2, ZrO2 in embodiment 1 is replaced by equimolar ZrOCl2·8H2O.

[0054] A preparation method of the high-temperature-resistant high-entropy mullite ceramic as described above, comprising the following steps:

[0055] S1, first, the raw materials are weighed according to the chemical composition and mass fraction of the high-temperature-resistant high-entropy mullite ceramic; then, the weighed high-temperature-resistant high-entropy mullite ceramic raw materials are poured into a ball mill tank, 28 mL of alcohol is added, the ball milling time is set to 9 h, the ball milling speed is 300 r / min, the ball mill is started to mix the high-temperature-resistant high-entropy mullite ceramic raw materials uniformly, and the prepared mixture is prepared for standby;

[0056] S2, the mixture prepared in step S1 is dried in an oven, the drying temperature is 80℃, and the drying time is 6h;

[0057] S3, the dried material in step S2 is weighed and placed in a tablet press mold for pressing and forming, the pressure is 20 MPa, and the pressure holding time is 10 min, and a blocky blank is prepared;

[0058] S4, the blocky blank prepared in step S3 is placed in a muffle furnace for blank sintering, and the temperature mechanism of the blank sintering is:

[0059] First stage: 0-1000℃, the heating rate is 5℃ / min;

[0060] Second stage: 1000-1400℃, the heating rate is 3℃ / min;

[0061] Third stage: 1400℃ for 1h;

[0062] Fourth stage: 1400-1600℃, the heating rate is 2℃ / min, and the holding time is 1h;

[0063] Cooling stage: naturally cooled to room temperature, and a high-entropy mullite blank is prepared.

[0064] The high-entropy mullite blank prepared in this embodiment 2 is subjected to XRD test, and the results are: the mullite phase content is 89.9%, the remaining phases are 7.9% chromium sesquioxide and 2.2% zirconium dioxide, and Rwp=8.3951%. Embodiment 3

[0065] A high-temperature-resistant high-entropy mullite ceramic, a chemical composition and mass fractions thereof are as follows: Al2O3: 1.3 g, SiO2: 0.5 g, TiO2: 0.14 g, Cr2O3: 0.26 g, MgO: 0.07 g, ZrOCl2*8H2O: 0.53 g, and MgO, ZrOCl2*8H2O, TiO2, and Cr2O3 are in an equimolar ratio.

[0066] A preparation method of the high-temperature-resistant high-entropy mullite ceramic as described above, comprising the following steps:

[0067] S1, first, raw materials are weighed according to the chemical composition and mass fractions of the high-temperature-resistant high-entropy mullite ceramic; then, the weighed high-temperature-resistant high-entropy mullite ceramic raw materials are poured into a ball mill tank, 28 mL of alcohol is added, the ball milling time is set to 9 h, the ball milling speed is 300 r / min, the ball mill is started to uniformly mix the high-temperature-resistant high-entropy mullite ceramic raw materials, and the prepared mixture is reserved;

[0068] S2, the mixture prepared in step S1 is subjected to drying treatment in an oven, the drying temperature is 80℃, and the drying time is 6 h;

[0069] S3, the material dried in step S2 is weighed and placed in a tablet press mold for compression molding, the pressure is 20 MPa, and the pressure holding time is 10 min, and a block-shaped blank is prepared;

[0070] S4, the block-shaped blank prepared in step S3 is placed in a muffle furnace for blank sintering, and the blank sintering temperature mechanism is as follows:

[0071] First stage: 0-1000℃, the heating rate is 5℃ / min;

[0072] Second stage: 1000-1400℃, the heating rate is 3℃ / min;

[0073] Third stage: 1400℃ for 1 h;

[0074] Fourth stage: 1400-1600℃, the heating rate is 2℃ / min, and the holding time is 1 h;

[0075] Cooling stage: naturally cooled to room temperature, and a high-entropy mullite blank is prepared.

[0076] The high-entropy mullite blank prepared in this embodiment 3 is subjected to XRD testing, and the XRD testing result is shown in Figure 4 , the result is that the mullite phase content is 95.9%, the remaining phase is 4.1% of zirconium dioxide, and Rwp=7.0690%; compared with embodiments 1 and 2, by using zirconium oxychloride instead of zirconium dioxide and reducing the addition amount of aluminum oxide, a high-entropy mullite blank with a mullite content as high as 95.9% is obtained.

[0077] Use of the high-entropy mullite ceramic blank prepared by the preparation method described above in preparation of an oxidation-resistant coating on a metal surface. The method for preparing the oxidation-resistant coating on the metal surface using the high-entropy mullite ceramic blank comprises the following steps:

[0078] S1, grinding the high-entropy mullite blank prepared in Example 3 to 50 mesh or less by mortar or ball milling to obtain a high-entropy mullite powder;

[0079] S2, first, the raw materials of the slurry are weighed according to the chemical composition and mass fraction thereof: 0.1 g of the high-entropy mullite powder prepared in step S1, 0.025 g of lead tetroxide powder, 0.05 g of copper oxide powder, and 0.005 g of zinc oxide powder; then, 4 drops of a binder (sodium silicate aqueous solution) are added dropwise to the raw materials of the slurry, the binder is used as a solvent, and the high-entropy mullite slurry is prepared after sufficient stirring;

[0080] S3, placing the polished metal block (in Example 3, the refractory high-entropy alloy TaWNbV is used as the metal substrate, and the oxidation temperature of the alloy is 700°C) into the high-entropy mullite slurry prepared in step S2, coating by the slurry coating method, taking out after uniform wrapping of the slurry, and then air-drying, and then performing coating sintering in a muffle furnace, and the temperature mechanism for coating sintering is:

[0081] First stage: 0-100°C, the heating rate is 4°C / min, and the holding time is 30 min;

[0082] Second stage: 100-300°C, the heating rate is 3°C / min, and the holding time is 1 h;

[0083] Third stage: 300-600°C, the heating rate is 10°C / min, and the holding time is 2 h;

[0084] Cooling stage: natural cooling to room temperature, and an oxidation-resistant coating is prepared on the surface of the metal block. The oxidation-resistant coating prepared by the preparation method is coated on the surface of the metal for oxidation resistance of the metal. The metal block with the oxidation-resistant coating on the surface is subjected to oxidation resistance tests at 700°C and 800°C for 1 h respectively, the mass difference at 700°C is 0.0732 g, and the mass difference at 800°C is 0.0228 g. Example 4

[0085] Use of the high-entropy mullite ceramic blank prepared by the preparation method described above in preparation of an oxidation-resistant coating on a metal surface. The method for preparing the oxidation-resistant coating on the metal surface using the high-entropy mullite ceramic blank comprises the following steps:

[0086] S1, grinding the high-entropy mullite blank prepared in Example 4 to 50 mesh or less by mortar or ball milling to obtain a high-entropy mullite powder;

[0087] S2, first, take the raw materials according to the chemical composition of the slurry and its mass fraction: 0.1 g of high-entropy mullite powder prepared in step S1, 0.05 g of lead tetroxide powder, 0.05 g of copper oxide powder, and 0.005 g of zinc oxide powder; then, 4 drops of a binder (sodium silicate aqueous solution) are added dropwise to the slurry raw materials, the binder is used as a solvent, and a high-entropy mullite slurry is prepared after sufficient stirring;

[0088] S3, place the polished metal block (in this embodiment 4, TaWNbV refractory high-entropy alloy is used as the metal substrate, and the alloy oxidation temperature is 700°C) into the high-entropy mullite slurry prepared in step S2, and use the slurry coating method for coating. After the slurry is evenly wrapped, it is taken out and dried, and then coating sintering is performed in a muffle furnace. The temperature mechanism for coating sintering is:

[0089] First stage: 0-100°C, heating rate 4°C / min, holding time 30 min;

[0090] Second stage: 100-300°C, heating rate 3°C / min, holding time 1 h;

[0091] Third stage: 300-600°C, heating rate 10°C / min, holding time 2 h;

[0092] Cooling stage: natural cooling to room temperature, to obtain an oxidation-resistant coating on the surface of the metal block. The metal block coated with the oxidation-resistant coating is subjected to 700 and 800°C oxidation-resistant tests for 1 h each. The mass difference at 700°C is 0.0025 g, and the mass difference at 800°C is 0.0005 g. Example 5

[0093] A high-temperature-resistant high-entropy mullite ceramic blank prepared by the same method as in Example 3 is used to prepare an oxidation-resistant coating on the surface of a metal. The method for preparing an oxidation-resistant coating on the surface of a metal using a high-temperature-resistant high-entropy mullite ceramic blank comprises the following steps:

[0094] S1, grind the high-entropy mullite blank prepared in this embodiment 5 to 50 mesh or less using a mortar or a ball mill to obtain a high-entropy mullite powder;

[0095] S2, first, take the raw materials according to the chemical composition of the slurry and its mass fraction: 0.1 g of high-entropy mullite powder prepared in step S1, 0.1 g of lead tetroxide powder, 0.05 g of copper oxide powder, and 0.005 g of zinc oxide powder; then, 4 drops of a binder (sodium silicate aqueous solution) are added dropwise to the slurry raw materials, the binder is used as a solvent, and a high-entropy mullite slurry is prepared after sufficient stirring;

[0096] S3, the polished metal block (in this embodiment 5, TaWNbV refractory high-entropy alloy is used as the metal substrate, and the alloy oxidation temperature is 700°C) is placed in the high-entropy mullite slurry prepared in step S2, and is coated by using the slurry coating method. After the slurry is evenly wrapped, the coated metal block is taken out and dried, and then is sintered in a muffle furnace. The temperature mechanism for the coating sintering is as follows:

[0097] First stage: 0-100°C, the temperature increasing rate is 4°C / min, and the holding time is 30 min;

[0098] Second stage: 100-300°C, the temperature increasing rate is 3°C / min, and the holding time is 1 h;

[0099] Third stage: 300-600°C, the temperature increasing rate is 10°C / min, and the holding time is 2 h;

[0100] Cooling stage: natural cooling to room temperature, and an oxidation-resistant coating is prepared on the surface of the metal block. The metal block with the oxidation-resistant coating on the surface is subjected to oxidation resistance tests at 700°C and 800°C for 1 h respectively, and the mass difference is 0.0057 g at 700°C and 0.0228 g at 800°C.

[0101] It can be known from the comparison of embodiments 3-5 that the oxidation-resistant coating prepared in embodiment 4 has the best performance. The following oxidation comparison tests of high-entropy mullite and pure mullite are carried out, i.e., on the basis of embodiment 4, the high-entropy mullite and pure mullite powders are ground to below 50 microns by using a mortar, 0.1 g of the high-entropy mullite powder and 0.1 g of the pure mullite powder, 0.05 g of lead tetroxide, 0.05 g of copper oxide and 0.005 g of zinc oxide are weighed, 4 drops of sodium silicate aqueous solution are added, and two portions of slurry are prepared. The TaWNbV refractory high-entropy alloy is placed in the slurry, and after being evenly coated, the coated metal block is taken out and dried, and then is sintered in a muffle furnace. The coating sintering mechanism is as follows: 0-100°C, 4°C / min temperature increasing, 100°C holding for 30 min; 100-300°C, 3°C / min temperature increasing, 300°C holding for 1 h; 300-600°C, 10°C / min temperature increasing, 600°C holding for 2 h, and natural cooling. Subsequently, the oxidation resistance tests at 700°C and 800°C for 1 h respectively are carried out, and the results are shown in Table 1.

[0102]

[0103] As can be directly seen from Table 1, the pure mullite coating cannot play an oxidation-resistant role, and the mass change difference is large. The oxidation-resistant effect of the high-entropy mullite coating is obvious.

[0104] From the above, it can be seen that the high-entropy mullite coating has the best oxidation-resistant effect. Figure 6It can be seen that the pure mullite coating has different degrees of oxidation phenomenon at 700 DEG C or 800 DEG C, resulting in cracking of the coating, while the high-entropy mullite surface has no cracking phenomenon, and the coating effect is good.

[0105] In summary, referring to Figure 4 It can be seen that the high-entropy mullite obtained in Example 3 has the highest content, up to 95.9%. Referring to Figure 5 It can be seen that, corresponding to Example 4, when Pb3O4 is added to 0.05g, the coating has the best oxidation resistance effect. Therefore, Example 3 is the optimal preparation scheme of high-entropy mullite blank, and Example 4 is the optimal preparation scheme of the oxidation-resistant coating, and the prepared high-entropy mullite and the commercially available mullite are compared, and the oxidation experiment achieves the ideal effect.

[0106] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any skilled person in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A high-temperature-resistant high-entropy mullite ceramic, characterized in that: The chemical composition of the high-temperature-resistant high-entropy mullite ceramic and the mass fraction thereof are as follows: 30-60 parts of aluminum oxide, 10-30 parts of silicon dioxide, 1-5 parts of magnesium oxide, 2-10 parts of titanium dioxide, 5-20 parts of dichromium trioxide, and 10-30 parts of zirconium oxychloride, and the ratio of the total mass of aluminum oxide and silicon dioxide to the total mass of the other four oxides is (1.5-3):(0.5-2). The preparation method of the high-temperature-resistant high-entropy mullite ceramic comprises the following steps: S1. First, raw materials are weighed according to the chemical composition and mass fraction of the high-temperature-resistant high-entropy mullite ceramic; then, the weighed high-temperature-resistant high-entropy mullite ceramic raw materials and 10-50 mL of alcohol are added to a ball mill, the ball milling time is set to 5-20 h, the ball milling speed is set to 100-500 rpm, and the ball mill is started to uniformly mix the high-temperature-resistant high-entropy mullite ceramic raw materials, and the prepared mixture is reserved; S2. The mixture prepared in step S1 is dried at a drying temperature of 50-150℃ for 1-10 h; S3. 0.5-2 g of the dried material in step S2 is pressed into a shape under a pressure of 5-30 MPa for 5-10 min to obtain a block-shaped blank; S4. The block-shaped blank prepared in step S3 is sintered at a sintering temperature of 1500-1800℃ to obtain a high-temperature-resistant high-entropy mullite ceramic blank. 2.The high-entropy mullite ceramic with high-temperature resistance of claim 1, characterized in that: The raw materials of the high-temperature-resistant high-entropy mullite ceramic are all in the form of powders, and the particle size of the powders is 1-100 microns.

3. The method of claim 1, wherein the high-temperature-resistant high-entropy mullite ceramic is prepared by the steps of: mixing a first powder and a second powder to form a mixture; and sintering the mixture to form the high-temperature-resistant high-entropy mullite ceramic. The preparation method comprises the following steps: S1. First, raw materials are weighed according to the chemical composition and mass fraction of the high-temperature-resistant high-entropy mullite ceramic; then, the weighed high-temperature-resistant high-entropy mullite ceramic raw materials and 10-50 mL of alcohol are added to a ball mill, the ball milling time is set to 5-20 h, the ball milling speed is set to 100-500 rpm, and the ball mill is started to uniformly mix the high-temperature-resistant high-entropy mullite ceramic raw materials, and the prepared mixture is reserved; S2. The mixture prepared in step S1 is dried at a drying temperature of 50-150℃ for 1-10 h; S3. 0.5-2 g of the dried material in step S2 is pressed into a shape under a pressure of 5-30 MPa for 5-10 min to obtain a block-shaped blank; S4. The block-shaped blank prepared in step S3 is sintered at a sintering temperature of 1500-1800℃ to obtain a high-temperature-resistant high-entropy mullite ceramic blank.

4. The preparation method of the high-temperature-resistant high-entropy mullite ceramic according to claim 3, characterized in that: In the step S4, the temperature mechanism of the blank sintering is as follows: First stage: 0-1000℃, the heating rate is 3-10℃ / min; Second stage: 1000-1400℃, the heating rate is 1-5℃ / min; Third stage: 1400℃ for 30 min-3h; Fourth stage: 1400-1800℃, the heating rate is 1-5℃ / min, and the holding time is 30 min-3h; Cooling stage: naturally cooled to room temperature.

5. A high-temperature-resistant high-entropy mullite ceramic blank prepared by the preparation method of claim 3 is used in the preparation of a metal surface oxidation-resistant coating.

6. Use according to claim 5, characterized in that: The method for preparing the metal surface oxidation-resistant coating by using the high-temperature-resistant high-entropy mullite ceramic blank comprises the following steps: S1, grinding the high-entropy mullite blank to 200 mesh or less to obtain high-entropy mullite powder; S2, first, the chemical composition and mass fraction of the slurry are determined: 30-70 parts of high-entropy mullite powder prepared in step S1, 10-50 parts of lead tetroxide powder, 10-50 parts of copper oxide powder, and 1-5 parts of zinc oxide powder; then, 2-7 drops of binder are added to the slurry raw materials as a solvent, and the high-entropy mullite slurry is prepared after sufficient stirring; S3, the polished metal block is placed in the high-entropy mullite slurry prepared in step S2, and after the slurry is evenly wrapped, it is taken out and dried, and then coating sintering is carried out, the sintering temperature is 300-600℃, and the holding time is 1-5h, and the oxidation-resistant coating is prepared on the surface of the metal block.

7. Use according to claim 6, characterized in that: In the step S2, the binder is sodium silicate aqueous solution, the slurry raw materials are all in the form of powder, and the particle size of the powder is 1-100 microns.

8. Use according to claim 6, characterized in that: In the step S3, the temperature mechanism of the coating sintering is: First stage: 0-100℃, heating rate 2-6℃ / min, holding time 10min-3h; Second stage: 100-300℃, heating rate 2-6℃ / min, holding time 1-3h; Third stage: 300-600℃, heating rate 5-15℃ / min, holding time 1-5h; Cooling stage: natural cooling to room temperature.

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