Sub-micron crystalline ceramic matrix composite material, preparation method and application thereof

Abstract

The application provides a sub-micrometer crystal ceramic matrix composite material and a preparation method and application thereof, and the preparation method comprises the following steps: coating at least two metal layers on the surface of a ceramic matrix pre-sintered body, and then sequentially performing vacuum sintering and hot isostatic pressing sintering to obtain the sub-micrometer crystal ceramic matrix composite material; the relative density of the ceramic matrix pre-sintered body is 80% to 92%, and the average grain size is less than 0.6 micrometers; by coating at least two metal layers on the surface of the ceramic matrix pre-sintered body, the ceramic matrix composite material is sintered and densified at a lower temperature, so that the contradiction between promoting sintering densification at a higher temperature and causing grain growth and inhibiting grain growth at a lower temperature but sintering not being dense is solved, and finally, the sub-micrometer crystal ceramic matrix composite material with an average grain size less than 1 micrometer and a relative density higher than 99.8% can be obtained; in addition, the vacuum sintering and the hot isostatic pressing sintering are not limited by the shape and size of the product, and batch production can be realized.

Description

Technical Field

[0001] This invention belongs to the field of ceramic matrix composite technology, and relates to a submicron crystalline ceramic matrix composite material, its preparation method and application. Background Technology

[0002] Ceramic matrix composites, including carbide-based, nitride-based, boride-based, and oxide-based composites, possess excellent wear resistance and are widely used in the manufacture of molds, cutting tools, and wear-resistant parts. However, the intrinsic brittleness of ceramic matrix composites limits their application range to some extent. The strength and toughness of ceramic matrix composites increase with decreasing grain size without significantly reducing other mechanical properties. For polycrystalline composites, those with an average grain size less than 0.1 μm are called nanocrystalline materials, those with an average grain size of 0.1 μm to 1 μm are called submicron crystalline materials, and those with an average grain size of 1 μm to 100 μm are called microcrystalline materials. However, current techniques for preparing ceramic matrix composites generally result in an average grain size greater than 2 μm, making it difficult to obtain submicron crystalline ceramic matrix composites.

[0003] Adding grain inhibitors can effectively suppress grain growth in ceramic matrix composites, but the addition of grain inhibitors will have an adverse effect on the performance of ceramic matrix composites; however, if the amount of grain inhibitors added is reduced, the effect of suppressing grain growth will be affected.

[0004] Lowering the sintering temperature and shortening the sintering time can also suppress grain growth, but this can lead to insufficient sintering density. To achieve both grain growth suppression and dense sintering, existing technologies employ hot pressing and spark plasma sintering. However, the poor electrical conductivity of most ceramic materials affects the sintering effect. Furthermore, these methods utilize external pressure during sintering to improve density, and the sintering temperature and time can be appropriately reduced to suppress grain growth. However, these methods have low production efficiency. Moreover, their biggest drawback is that they can only produce products with relatively simple shapes, and the product size is limited.

[0005] Hot isostatic pressing (HIP) sintersulates products under pressure, allowing for mass production without being limited by product shape and promoting densification at relatively low temperatures. However, before HIP sintering, the pre-sintered body needs to have a relative density of over 93%, meaning its interior must be a closed pore structure to prevent high-pressure gas from entering during HIP sintering and ensure dense sintering. However, achieving a relative density of over 93% requires increasing the sintering temperature, which can lead to grain growth.

[0006] It is evident that existing technologies present a contradiction: higher temperatures promote sintering densification but lead to grain growth, while lower temperatures inhibit grain growth but result in less dense sintering. How to obtain dense submicron crystalline ceramic matrix composites and achieve mass production without being limited by product shape and size is a problem that urgently needs to be solved in this field. Summary of the Invention

[0007] The purpose of this invention is to provide a submicron crystalline ceramic matrix composite material, its preparation method and application, to solve the contradiction in the prior art where higher temperatures promote sintering densification but lead to grain growth, while lower temperatures inhibit grain growth but result in non-densified sintering, thereby obtaining a dense submicron crystalline ceramic matrix composite material.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a method for preparing a submicron crystalline ceramic matrix composite material, the method comprising the following steps:

[0010] At least two metal layers are coated on the surface of the ceramic matrix pre-sintered body, and then vacuum sintering and hot isostatic pressing are performed in sequence to obtain the submicron crystalline ceramic matrix composite material.

[0011] The relative density of the ceramic-based presintered body is 80% to 92%, and the average grain size of the ceramic-based presintered body is less than 0.6 μm.

[0012] Of the at least two metal layers, the melting point T of the outermost metal layer is... m2 The melting point T is higher than that of the innermost metal layer. m1 And the temperature T1 of vacuum sintering.

[0013] The melting point T of the innermost metal layer m1 The temperature is 0°C to 20°C lower than the vacuum sintering temperature T1.

[0014] In the at least two metal layers, the melting point of each metal layer is higher than the temperature T2 of hot isostatic pressing sintering.

[0015] The preparation method provided by this invention involves coating the surface of a ceramic-based pre-sintered body with at least two metal layers, melting the innermost metal layer through vacuum sintering to form a dense metal sealing layer on the surface of the ceramic-based pre-sintered body, and then performing hot isostatic pressing sintering at a lower temperature than the melting point of the innermost metal layer. This method maintains the innermost metal layer as a solid and with good plasticity, which not only prevents high-pressure gas from entering the ceramic-based pre-sintered body but also transmits pressure evenly and effectively to the pre-sintered body. This ensures the densification of the submicron-sized ceramic matrix composite material and effectively inhibits grain growth. That is, by coating the surface of the ceramic matrix pre-sintered body with at least two metal layers, the submicron crystalline ceramic matrix composite material is sintered and densified at a lower temperature. This solves the contradiction between higher temperatures promoting sintering densification but causing grain growth and lower temperatures inhibiting grain growth but resulting in non-densified sintering. Ultimately, a submicron crystalline ceramic matrix composite material with an average grain size of submicron (less than 1 μm) and a relative density higher than 99.8% can be obtained. In addition, vacuum sintering and hot isostatic pressing are not limited by the shape and size of the product and can achieve mass production.

[0016] This invention does not impose specific limitations on the exact shape or preparation method of the ceramic-based presintered body, as long as its relative density is between 80% and 92% and its average grain size is below 0.6 μm. The relative density of the ceramic-based presintered body refers to the ratio of its density to the theoretical density of the submicron-crystalline ceramic matrix composite material.

[0017] The innermost metal layer in this invention refers to the metal layer closest to the ceramic-based pre-sintered body among at least two metal layers; the outermost metal layer refers to the metal layer furthest from the ceramic-based pre-sintered body among at least two metal layers.

[0018] Preferably, the melting point T of the innermost metal layer m1 The temperature ranges from 1430℃ to 1852℃.

[0019] Preferably, the material of the innermost metal layer includes any one or a combination of at least two of Ni, Co, Fe, Ti or Zr.

[0020] Preferably, the outermost metal layer is made of any one or a combination of at least two of Ti, Zr, Mo, Nb, or Ta.

[0021] Preferably, the thickness of the innermost metal layer is 0.1 mm to 0.5 mm.

[0022] Preferably, the thickness of the outermost metal layer is 0.1 mm to 0.3 mm.

[0023] Preferably, the vacuum sintering temperature T1 is between 1430°C and 1872°C.

[0024] Preferably, the holding time for vacuum sintering is 0.5h to 1h.

[0025] Preferably, the vacuum sintering is performed at a pressure of 10... -3 Perform below Pa.

[0026] Preferably, the hot isostatic pressing sintering is carried out in an inert atmosphere.

[0027] Preferably, the pressure of the hot isostatic pressing sintering is 150 MPa to 300 MPa.

[0028] Preferably, the temperature T2 of the hot isostatic pressing sintering is higher than the melting point T of the innermost metal layer. m1 Temperatures can drop by 10°C to 50°C.

[0029] Preferably, the temperature T2 of the hot isostatic pressing sintering is between 1380°C and 1842°C.

[0030] Preferably, the holding time for hot isostatic pressing sintering is 1 hour to 3 hours.

[0031] Preferably, the method for preparing the ceramic-based pre-sintered body includes sequentially performing powder mixing, molding, degreasing, and vacuum pre-sintering.

[0032] Preferably, the vacuum pre-sintering temperature T3 is between 1400°C and 1910°C.

[0033] Preferably, the holding time for vacuum pre-sintering is 1 hour to 3 hours.

[0034] Preferably, the vacuum pre-sintering is carried out at a pressure below 30 Pa.

[0035] Preferably, the raw materials for preparing the submicron crystalline oxide ceramic matrix composite material, by volume percentage, include: more than 50 vol% of oxide ceramic matrix, less than 49.5 vol% of additives, and less than 0.5 vol% of sintering aid.

[0036] Preferably, the raw materials for preparing the submicron crystalline nitride ceramic matrix composite material, by volume percentage, include: more than 50 vol% nitride ceramic matrix, less than 49.5 vol% additives, and less than 0.5 vol% sintering aids.

[0037] Preferably, the raw materials for preparing the submicron crystalline boride ceramic matrix composite material, by volume percentage, include: more than 50 vol% boride ceramic matrix, less than 49.5 vol% additives, and less than 0.5 vol% sintering aids.

[0038] Preferably, the raw materials for preparing the submicron crystalline carbide ceramic matrix composite material, by volume percentage, include: more than 50 vol% of carbide ceramic matrix, less than 49.5 vol% of additives, and less than 0.5 vol% of sintering aid.

[0039] In a second aspect, the present invention provides a submicron crystalline ceramic matrix composite material, which is prepared by the preparation method described in the first aspect.

[0040] The submicron crystalline ceramic matrix composite material has an average grain size of less than 1 μm and a relative density of more than 99.8%.

[0041] Thirdly, the present invention provides an application of a submicron crystalline ceramic matrix composite material, which is used to prepare molds, cutting tools or wear-resistant parts.

[0042] The submicron crystalline ceramic matrix composite material is prepared by the preparation method described in the first aspect, or is the submicron crystalline ceramic matrix composite material described in the second aspect.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] (1) The preparation method provided by the present invention achieves the sintering and densification of submicron crystalline ceramic matrix composite material at a lower temperature by coating the surface of the ceramic matrix pre-sintered body with at least two metal layers. This solves the contradiction between higher temperature promoting sintering densification but causing grain growth and lower temperature inhibiting grain growth but not achieving densification. Finally, a submicron crystalline ceramic matrix composite material with an average grain size of submicron (less than 1 μm) and a relative density of more than 99.8% can be obtained. In addition, vacuum sintering and hot isostatic pressing are not limited by the shape and size of the product and can achieve mass production.

[0045] (2) The average grain size of the submicron crystalline ceramic matrix composite material prepared by the present invention is submicron (less than 1 μm), and the relative density is higher than 99.8%. Detailed Implementation

[0046] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely for the purpose of helping to understand the present invention and should not be considered as specific limitations of the present invention.

[0047] An embodiment of the present invention provides a method for preparing a submicron crystalline ceramic matrix composite material, the method comprising the following steps:

[0048] At least two metal layers are coated on the surface of the ceramic matrix pre-sintered body, and then vacuum sintering and hot isostatic pressing are performed in sequence to obtain the submicron crystalline ceramic matrix composite material.

[0049] The relative density of the ceramic-based presintered body is 80% to 92%, and the average grain size of the ceramic-based presintered body is less than 0.6 μm.

[0050] Of the at least two metal layers, the melting point T of the outermost metal layer is... m2 The melting point T is higher than that of the innermost metal layer. m1 And the temperature T1 of vacuum sintering.

[0051] The melting point T of the innermost metal layer m1 The temperature is 0°C to 20°C lower than the vacuum sintering temperature T1.

[0052] In the at least two metal layers, the melting point of each metal layer is higher than the temperature T2 of hot isostatic pressing sintering.

[0053] The preparation method provided by this invention involves coating the surface of a ceramic-based pre-sintered body with at least two metal layers, melting the innermost metal layer through vacuum sintering to form a dense metal sealing layer on the surface of the ceramic-based pre-sintered body, and then performing hot isostatic pressing sintering at a lower temperature than the melting point of the innermost metal layer. This method maintains the innermost metal layer as a solid and with good plasticity, which not only prevents high-pressure gas from entering the ceramic-based pre-sintered body but also transmits pressure evenly and effectively to the pre-sintered body. This ensures the densification of the submicron-sized ceramic matrix composite material and effectively inhibits grain growth. That is, by coating the surface of the ceramic matrix pre-sintered body with at least two metal layers, the submicron crystalline ceramic matrix composite material is sintered and densified at a lower temperature. This solves the contradiction between higher temperatures promoting sintering densification but causing grain growth and lower temperatures inhibiting grain growth but resulting in non-densified sintering. Ultimately, a submicron crystalline ceramic matrix composite material with an average grain size of submicron (less than 1 μm) and a relative density higher than 99.8% can be obtained. In addition, vacuum sintering and hot isostatic pressing are not limited by the shape and size of the product and can achieve mass production.

[0054] This invention does not impose specific limitations on the exact shape or preparation method of the ceramic-based presintered body, as long as its relative density is between 80% and 92% and its average grain size is below 0.6 μm. The relative density of the ceramic-based presintered body refers to the ratio of its density to the theoretical density of the submicron-crystalline ceramic matrix composite material.

[0055] The innermost metal layer in this invention refers to the metal layer closest to the ceramic-based pre-sintered body among at least two metal layers; the outermost metal layer refers to the metal layer furthest from the ceramic-based pre-sintered body among at least two metal layers.

[0056] In the preparation method provided by the present invention, the average grain size of the ceramic-based pre-sintered body is less than 0.6 μm and the relative density is 80% to 92%, for example, it can be 80%, 85%, 88%, 90% or 92%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0057] In some embodiments, the melting point T of the innermost metal layer m1 The temperature ranges from 1430°C to 1852°C, for example, 1430°C, 1450°C, 1500°C, 1600°C, 1700°C, 1800°C, 1830°C, or 1852°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable. To facilitate the covering of ceramic-based pre-sintered bodies of arbitrary shapes with at least two metal layers, the material of the at least two metal layers has good room-temperature plasticity.

[0058] In some embodiments, the material of the innermost metal layer includes any one or a combination of at least two of Ni (melting point 1455°C), Co (melting point 1495°C), Fe (melting point 1538°C), Ti (melting point 1668°C), or Zr (melting point 1852°C). Typical but non-limiting combinations include combinations of Ni and Co, Ni and Fe, Fe and Ti, Ni, Co and Fe, Co, Fe and Ti, or Ni, Co, Fe and Ti. Such combinations include a simple mixture of at least two metals or an alloy comprising at least two metallic elements.

[0059] In the preparation method provided by this invention, the melting point T of the outermost metal layer m2 The melting point T is higher than that of the innermost metal layer. m1 Throughout the entire preparation process, the outermost metal layer remains solid, thereby preventing the remaining metal layers from being lost due to gravity during vacuum sintering and hot isostatic pressing, thus ensuring the complete coating effect of the inner metal layer on the ceramic-based pre-sintered body.

[0060] In some embodiments, the outermost metal layer is made of any one or a combination of at least two of Ti (melting point 1668°C), Zr (melting point 1852°C), Mo (melting point 2623°C), Nb (melting point 2468°C), or Ta (melting point 2996°C). Typical but non-limiting combinations include combinations of Ti and Zr, Zr and Mo, Mo and Nb, Nb and Ta, or Ti, Zr, Mo, Nb and Ta. These combinations include simple mixtures of at least two metals or alloys comprising at least two metallic elements.

[0061] The method of coating the surface of the ceramic-based presintered body with at least two metal layers is a conventional coating method, as long as the non-airtight coating of the metal layers on the surface of the ceramic-based presintered body can be achieved.

[0062] For example, methods for coating the surface of a ceramic-based presintered body with an innermost metal layer include spraying or applying a thin-walled metal part.

[0063] In some embodiments, when coating the innermost metal layer, the spraying method includes: uniformly spraying a slurry containing coating metal powder onto the surface of the ceramic-based pre-sintered body, and drying it to form the innermost metal coating layer.

[0064] In some embodiments, when covering the innermost metal layer, the method of fitting the thin-walled metal components includes: preparing the metal to be covered into multiple thin-walled components with the same shape as the ceramic-based pre-sintered body; fitting the multiple thin-walled components together and tightly adhering to the surface of the ceramic-based pre-sintered body; and connecting the interfaces of the multiple thin-walled components through nesting to form the innermost metal covering layer.

[0065] An example method of covering the outermost metal layer includes wearing a thin-walled metal component.

[0066] In some embodiments, when covering the outermost metal layer, the method of fitting the thin-walled metal components includes: preparing the metal to be covered into multiple thin-walled components with the same shape as the ceramic-based pre-sintered body already covered with the inner metal layer; fitting the multiple thin-walled components together and tightly adhering to the outer surface of the ceramic-based pre-sintered body already covered with the inner metal layer; and connecting the interfaces of the multiple thin-walled components through nesting to form the outermost metal covering layer.

[0067] This invention uses at least two metal layers to coat a ceramic-based pre-sintered body. If the innermost metal layer is too thin, the seal will be insufficient, allowing high-pressure gas to diffuse into the pre-sintered body during hot isostatic pressing (HIP), resulting in a less dense sintering. However, if it is too thick, the processing cost will be high. Similarly, if the outermost metal layer is too thin, the protective effect will be reduced. Furthermore, if it is too thick, the processing cost will also be high because the metal layer needs to be removed later. Therefore, to achieve good protection, the thicknesses of the innermost and outermost metal layers need to be optimally selected.

[0068] In some embodiments, the thickness of the innermost metal layer is 0.1 mm to 0.5 mm, for example, it can be 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm or 0.5 mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0069] In some embodiments, the thickness of the outermost metal layer is 0.1 mm to 0.3 mm, for example, it can be 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm or 0.3 mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0070] The total thickness of the at least two metal layers is related to the number of metal layers. In this invention, it is only necessary to control the thickness of the innermost metal layer and the thickness of the outermost metal layer.

[0071] In this invention, during vacuum sintering, the vacuum sintering temperature T1 must be equal to or greater than the melting point T of the innermost metal layer. m1 In other words, the innermost metal layer needs to be melted to completely seal the ceramic-based pre-sintered body; however, it is also necessary to prevent further increase in the grain size of the ceramic-based pre-sintered body, so the vacuum sintering temperature cannot be too high. Furthermore, before the innermost metal layer is completely melted and sealed, various reactions within the ceramic-based pre-sintered body that are detrimental to sintering and easily form gases must be completed; otherwise, these gases cannot escape from the ceramic-based pre-sintered body and will be sealed inside, forming pores. This means that hot isostatic pressing (HIP) cannot eliminate these pores, leading to a deterioration in the performance of the final product. Therefore, optimal control of the vacuum sintering temperature is required.

[0072] In some embodiments, the vacuum sintering temperature is between 1430°C and 1872°C, for example, 1430°C, 1450°C, 1500°C, 1600°C, 1700°C, 1800°C or 1872°C, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0073] In some embodiments, the holding time for vacuum sintering is 0.5h to 1h, for example, it can be 0.5h, 0.6h, 0.8h, 0.9h or 1h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0074] In some embodiments, the vacuum sintering is performed at a pressure of 10... -3 The reaction is carried out below Pa to avoid the gas generated by the reaction being sealed within the ceramic-based pre-sintered body.

[0075] In some embodiments, the hot isostatic pressing sintering is performed in an inert atmosphere.

[0076] The inert atmosphere includes inert gases such as nitrogen and / or argon.

[0077] In some embodiments, the pressure of the hot isostatic pressing sintering is from 150 MPa to 300 MPa, for example, it can be 150 MPa, 180 MPa, 200 MPa, 240 MPa, 250 MPa, 280 MPa or 300 MPa, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0078] In this invention, under the premise of ensuring that the ceramic-based pre-sintered body is sintered to be dense, a lower hot isostatic pressing temperature is more conducive to suppressing grain growth.

[0079] In some embodiments, the hot isostatic pressing sintering temperature T2 is higher than the melting point T of the innermost metal layer. m1 The temperature range is 10°C lower to 50°C, for example, 10°C, 20°C, 30°C, 40°C, or 50°C, but not limited to the listed values. Other unlisted values ​​within this range also apply. Within this temperature range, hot isostatic pressing (HIP) sintering can maintain the innermost metal layer in a solid, sealed state, reducing its diffusion capacity under high pressure and further preventing high-pressure gas from diffusing into the ceramic matrix pre-sintered body. Moreover, within this temperature range, it can maintain good plasticity, thereby ensuring that pressure can be effectively transmitted to the pre-sintered body and promoting its densification.

[0080] In some embodiments, the hot isostatic pressing sintering temperature T2 is between 1380°C and 1842°C, for example, it can be 1380°C, 1400°C, 1500°C, 1600°C, 1700°C, 1800°C, 1820°C or 1842°C, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0081] In some embodiments, the holding time for hot isostatic pressing sintering is 1 hour to 3 hours, for example, it can be 1 hour, 1.5 hours, 2 hours, 2.5 hours or 3 hours, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0082] In some embodiments, the method for preparing the ceramic-based pre-sintered body includes sequentially performing powder mixing, molding, debinding, and vacuum pre-sintering.

[0083] In some embodiments, the powder mixing is performed by ball milling according to the composition formulation of the submicron crystalline ceramic matrix composite material to obtain a uniformly mixed powder.

[0084] In some embodiments, the ball milling process includes: placing the formulated amount of raw material powder into a ball mill, then injecting anhydrous ethanol into the ball mill, and ball milling and mixing for more than 24 hours in a protective atmosphere to obtain a uniformly mixed powder with an average particle size of not more than 0.3 μm.

[0085] In some embodiments, the grinding balls used in the ball milling mixture are made of materials including zirconium oxide, alumina, silicon carbide, silicon nitride, or cemented carbide, and the mass ratio of the grinding balls to the raw material powder is 2:1 to 8:1, for example, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, or 8:1, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0086] In some embodiments, the molding process includes at least one of compression molding, cold isostatic pressing, extrusion molding, injection molding, or 3D printing. This invention does not specifically limit the molding method, as long as a molded body of the desired shape can be obtained. When the desired shape cannot be obtained through a one-step molding process, the molding process further includes machining.

[0087] In some embodiments, the degreasing is performed by inert gas negative pressure degreasing or hydrogen positive pressure degreasing.

[0088] In some embodiments, if the shape of the degreased molded body is inconsistent with the shape of the target product, cutting processing is performed after degreasing.

[0089] In this invention, the vacuum pre-sintering temperature T3 is crucial for obtaining a ceramic matrix pre-sintered body with a relative density of 80% to 92% and an average grain size of less than 0.6 μm. If the vacuum pre-sintering temperature T3 is too low, the resulting ceramic matrix pre-sintered body will not grow excessively and will have a smaller grain size. However, the relative density of the ceramic matrix pre-sintered body will be less than 80%, and there will be more pores, resulting in lower strength of the ceramic matrix pre-sintered body. This leads to the following two adverse results: (1) Due to the low strength of the ceramic matrix pre-sintered body, it is not conducive to the operation of coating a metal layer on its surface, and the pre-sintered body is easily damaged; (2) Due to the large number of pores, during subsequent vacuum sintering, the liquid metal phase formed after the innermost metal layer melts is easy to diffuse into the interior of the ceramic matrix pre-sintered body along the pores, resulting in excessive diffusion depth, which affects the surface quality of the final submicron crystalline ceramic matrix composite material. If the vacuum pre-sintering temperature is too high, although it can increase the relative density of the ceramic matrix pre-sintered body, it is impossible to obtain submicron sized grains.

[0090] In some embodiments, the vacuum pre-sintering temperature T3 is 1400°C to 1910°C, for example, it can be 1400°C, 1500°C, 1600°C, 1700°C, 1800°C, 1850°C or 1910°C, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0091] In some embodiments, the holding time for vacuum pre-sintering is 1 hour to 3 hours, for example, it can be 1 hour, 1.5 hours, 2 hours, 2.5 hours or 3 hours, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0092] In some embodiments, the vacuum pre-sintering is performed at a pressure below 30 Pa.

[0093] In some embodiments, the submicron-crystalline ceramic matrix composite material includes any one of submicron-crystalline oxide ceramic matrix composite material, submicron-crystalline nitride ceramic matrix composite material, submicron-crystalline boride ceramic matrix composite material, or submicron-crystalline carbide ceramic matrix composite material.

[0094] In some embodiments, the raw materials for preparing the submicron crystalline oxide ceramic matrix composite material, by volume percentage, include: more than 50 vol% of oxide ceramic matrix, less than 49.5 vol% of additives, and less than 0.5 vol% of sintering aid.

[0095] In some embodiments, the oxide ceramic matrix includes any one or a combination of at least two of Al2O3, ZrO2, or SiO2.

[0096] In some embodiments, the additive includes any one or a combination of at least two of the following: WC, Cr3C2, VC, ZrC, TiC, TiCN, Mo2C, TaC, NbC, SiC, B4C, ZrB, ZrB2, TiB, TiB2, WB, W2B, W2B5, CrB, SiAlON, BN, AlN, ZrN, TiN, MgO, rare earth metal oxides, or rare earth metal borides.

[0097] In some embodiments, the sintering aid includes any one or a combination of at least two of Co, Ni, Fe, or Ti.

[0098] In some embodiments, the raw materials for preparing the submicron crystalline nitride ceramic matrix composite material, by volume percentage, include: more than 50 vol% of nitride ceramic matrix, less than 49.5 vol% of additives, and less than 0.5 vol% of sintering aid.

[0099] In some embodiments, the nitride ceramic matrix includes any one or a combination of at least two of SiAlON, BN, AlN, or TiN.

[0100] In some embodiments, the additive includes any one or a combination of at least two of the following: WC, Cr3C2, VC, ZrC, TiC, TiCN, Mo2C, TaC, NbC, SiC, B4C, ZrB, ZrB2, TiB, TiB2, WB, W2B, W2B5, CrB, ZrN, TiN, Al2O3, ZrO2, MgO, SiO2, rare earth metal oxides, or rare earth metal borides.

[0101] In some embodiments, the sintering aid includes any one or a combination of at least two of Co, Ni, Fe, Ti, C, or B.

[0102] In some embodiments, the raw materials for preparing the submicron crystalline boride ceramic matrix composite material, by volume percentage, include: more than 50 vol% boride ceramic matrix, less than 49.5 vol% additives, and less than 0.5 vol% sintering aids.

[0103] In some embodiments, the boride ceramic matrix comprises ZrB2 and / or TiB2.

[0104] In some embodiments, the additive includes any one or a combination of at least two of the following: WC, Cr3C2, VC, ZrC, TiC, TiCN, Mo2C, TaC, NbC, SiC, B4C, ZrB, TiB, WB, W2B, W2B5, CrB, SiAlON, BN, AlN, ZrN, TiN, Al2O3, ZrO2, MgO, SiO2, rare earth metal oxides, or rare earth metal borides.

[0105] In some embodiments, the sintering aid includes any one or a combination of at least two of Co, Ni, Fe, Ti, C, or B.

[0106] In some embodiments, the raw materials for preparing the submicron crystalline carbide ceramic matrix composite material, by volume percentage, include: more than 50 vol% of carbide ceramic matrix, less than 49.5 vol% of additives, and less than 0.5 vol% of sintering aid.

[0107] In some embodiments, the carbide ceramic matrix includes any one or a combination of at least two of TiCN, TiC, ZrC, SiC, or B4C.

[0108] In some embodiments, the additive includes any one or a combination of at least two of the following: WC, Cr3C2, VC, Mo2C, TaC, NbC, SiC whiskers, ZrB, ZrB2, TiB, TiB2, WB, W2B, W2B5, CrB, SiAlON, BN, AlN, ZrN, TiN, Al2O3, ZrO2, MgO, SiO2, rare earth metal oxides, or rare earth metal borides.

[0109] In some embodiments, the sintering aid includes any one or a combination of at least two of Co, Ni, Fe, Ti, C, or B.

[0110] One embodiment of the present invention provides a submicron crystalline ceramic matrix composite material, which is prepared by the preparation method described in any embodiment.

[0111] The submicron crystalline ceramic matrix composite material has an average grain size of less than 1 μm and a relative density of more than 99.8%.

[0112] One embodiment of the present invention provides an application of a submicron crystalline ceramic matrix composite material, which is used to prepare molds, cutting tools or wear-resistant parts.

[0113] The submicron crystalline ceramic matrix composite material is prepared by the preparation method described in any embodiment, or is the submicron crystalline ceramic matrix composite material described in any embodiment.

[0114] Preparation of pre-sintered body

[0115] Preparation Example 1

[0116] This preparation example provides a method for preparing a ceramic-based pre-sintered body. The raw material powder for the ceramic-based pre-sintered body, by volume percentage, comprises 70 vol% Al₂O₃ and 22 vol% SiC. w The preparation method using whiskers, 5.5 vol% MgO, and 2.5 vol% Y₂O₃ includes the following steps:

[0117] (1) In a nitrogen atmosphere, the raw material powder is placed in a ball mill and ball-milled with alumina grinding balls and anhydrous ethanol for 24 hours to make the average particle size of the resulting mixed powder less than 0.3 μm; wherein the mass ratio of grinding balls to raw material powder is 2:1.

[0118] (2) The molded body is obtained by cold isostatic pressing at a pressure of 200 MPa;

[0119] (3) The first, second, third, and fourth degreasing stages are performed sequentially. The first, second, and third degreasing stages are conducted in an argon atmosphere at a pressure of 400 Pa.

[0120] First defatting stage: After 3 hours, the temperature is uniformly increased from room temperature (25℃) to 120℃;

[0121] Second defatting stage: After 6 hours, the temperature is uniformly increased from 120℃ to 360℃;

[0122] Third degreasing stage: Keep warm at 360℃ for 3 hours;

[0123] Fourth degreasing stage: Stop filling with argon gas and evacuate to a pressure below 30Pa. Raise the temperature uniformly from 360℃ to 650℃ and hold for 1 hour.

[0124] (4) Under pressure below 30 Pa, vacuum pre-sintering was carried out at a temperature of 1480 °C for 2 h (holding time) to obtain a pre-sintered body with a relative density of 84%.

[0125] In Table 1, Preparation Example 2, Preparation Example 3, Comparative Preparation Example 1, and Comparative Preparation Example 2 are identical to Preparation Example 1 except for the parameters and conditions of vacuum pre-sintering.

[0126] Table 1. Experimental parameters and results of each preparation example and the comparative preparation example

[0127]

[0128] Preparation Example 4

[0129] This preparation example provides a method for preparing a ceramic-based presintered body. The raw material powder of the ceramic-based presintered body includes 97.4 vol% SiAlON, 1.3 vol% Y2O3, 0.7 vol% La2O3 and 0.6 vol% CeO2 by volume percentage.

[0130] In the preparation method described, except that the vacuum pre-sintering temperature T3 is 1700℃, the rest are the same as in preparation example 1.

[0131] The pre-sintered body obtained in this preparation example has a relative density of 86% and an average grain size of 0.543 μm.

[0132] Preparation Example 5

[0133] This preparation example provides a method for preparing a ceramic-based pre-sintered body. The raw material powder of the ceramic-based pre-sintered body includes 93.5 vol% TiCN, 4 vol% WC, 2 vol% ZrC, 0.3 vol% Cr3C2 and 0.2 vol% VC by volume percentage.

[0134] In the preparation method described, except that the vacuum pre-sintering temperature T3 is 1840℃, the rest are the same as in preparation example 1.

[0135] The pre-sintered body obtained in this preparation example has a relative density of 86% and an average grain size of 0.513 μm.

[0136] Preparation Example 6

[0137] This preparation example provides a method for preparing a ceramic-based pre-sintered body. The raw material powder of the ceramic-based pre-sintered body includes 75 vol% TiB2, 20 vol% B4C, 2.5 vol% SiC, 2 vol% Mo2C and 0.5 vol% B by volume.

[0138] In the preparation method described, except that the vacuum pre-sintering temperature T3 is 1880℃, the rest are the same as in preparation example 1.

[0139] The pre-sintered body obtained in this preparation example has a relative density of 82% and an average grain size of 0.525 μm.

[0140] Example 1-1

[0141] This embodiment provides a method for preparing submicron crystalline ceramic matrix composite materials, the method comprising the following steps:

[0142] (a) Two metal layers are coated on the surface of the ceramic-based pre-sintered body; wherein the innermost metal layer is made of nickel (melting point T). m1 The outermost metal layer is made of titanium (melting point T1455℃), with a thickness of 0.3mm; the outermost metal layer is made of titanium (melting point T1455℃). m2 (Temperature: 1668℃), thickness: 0.2mm;

[0143] The innermost metal layer is coated by spraying; the outermost metal layer is coated by using a thin-walled metal fitting method.

[0144] The ceramic-based presintered body is the ceramic-based presintered body provided in Preparation Example 1;

[0145] (b) At a pressure of 10 -3 Vacuum sintering was carried out under conditions below Pa, with a vacuum sintering temperature T1 of 1455℃ and a holding time of 1h.

[0146] (c) Hot isostatic pressing was carried out under an argon atmosphere at a pressure of 170 MPa, a temperature T2 of 1420 °C, and a holding time of 1.5 h to obtain a submicron crystalline ceramic matrix composite material.

[0147] The submicron-sized ceramic matrix composite material obtained in this embodiment is fully sintered and dense, with a relative density of 100% and an average grain size of 0.834 μm.

[0148] Examples 1-2

[0149] This embodiment provides a method for preparing submicron crystalline ceramic matrix composite material. Except for the vacuum sintering temperature T1 being 1475℃ and the holding time being 0.5h, the rest is the same as in Example 1-1.

[0150] Compared with Example 1-1, this example increases the vacuum sintering temperature, but due to the reduction in holding time, the submicron crystalline ceramic matrix composite material obtained in this example is fully sintered and dense, with a relative density of 100%, and the average grain size increases slightly to 0.848 μm.

[0151] Examples 1-3

[0152] This embodiment provides a method for preparing submicron crystalline ceramic matrix composite materials. Except for the hot isostatic pressing sintering temperature T2 being 1445℃ and the holding time being 1h, the rest is the same as in Example 1-1.

[0153] Compared with Example 1-1, this example increases the hot isostatic pressing sintering temperature, resulting in a fully sintered and dense submicron crystalline ceramic matrix composite material with a relative density of 100% and a slight increase in the average grain size to 0.841 μm.

[0154] Examples 1-4

[0155] This embodiment provides a method for preparing submicron crystalline ceramic matrix composite materials. Except for the hot isostatic pressing sintering temperature T2 being 1405℃ and the holding time being 3h, the rest is the same as in Example 1-1.

[0156] Compared with Example 1-1, this example lowers the hot isostatic pressing sintering temperature and increases the holding time. The sintering density of the submicron crystalline ceramic matrix composite material obtained in this example is slightly worse, with a relative density of 99.91%, but the average grain size is slightly reduced to 0.822 μm.

[0157] Examples 1-5

[0158] This embodiment provides a method for preparing submicron crystalline ceramic matrix composite materials. Except for the hot isostatic pressing sintering temperature T2 of 1390℃, the rest is the same as in Example 1-1.

[0159] Compared with Examples 1-4, this example further reduces the temperature of hot isostatic pressing, resulting in a further reduction in the density of the submicron crystalline ceramic matrix composite material obtained in this example. The relative density reaches 99.82%, and the average grain size is further reduced to 0.816 μm.

[0160] Example 2

[0161] This embodiment provides a method for preparing submicron crystalline ceramic matrix composite materials. Except that the ceramic matrix pre-sintered body is the same as the ceramic matrix pre-sintered body provided in Preparation Example 2, the rest are the same as in Examples 1-1.

[0162] Compared to Example 1-1, this example has a slightly lower surface quality of the submicron-sized ceramic matrix composite material because the relative density of the ceramic matrix pre-sintered body is reduced. This results in a slight diffusion of the molten liquid phase along the pores on the surface of the pre-sintered body after the innermost metal layer melts during vacuum sintering. However, due to the lower vacuum pre-sintering temperature, the average grain size of the pre-sintered ceramic matrix is ​​finer. Under the same vacuum sintering and hot isostatic pressing process as in Example 1-1, the resulting submicron-sized ceramic matrix composite material is also completely dense, with a relative density of 100%. Furthermore, due to the increased porosity, the distance for grain diffusion and growth during sintering is relatively increased, thereby improving the energy for grain growth. Therefore, the average grain size of the resulting submicron-sized ceramic matrix composite material is also finer than that of Example 1-1, reaching 0.797 μm.

[0163] Example 3

[0164] This embodiment provides a method for preparing submicron crystalline ceramic matrix composite materials. Except that the pre-sintered body is the same as the pre-sintered body provided in Preparation Example 3, the rest are the same as in Examples 1-1.

[0165] Compared to Examples 1-1, this example provides a ceramic-based pre-sintered body from Preparation Example 3. Clearly, the vacuum pre-sintering temperature is increased, and the relative density of the ceramic-based pre-sintered body provided in Preparation Example 3 increases to 92%, while the average grain size also grows to 0.596 μm. Under the subsequent vacuum sintering and hot isostatic pressing processes identical to those in Examples 1-1, the resulting submicron-crystalline ceramic matrix composite material is also completely dense, achieving a relative density of 100%, but the average grain size increases to 0.968 μm.

[0166] Example 4

[0167] This embodiment provides a method for preparing submicron crystalline ceramic matrix composite materials, the method comprising the following steps:

[0168] (a) Two metal layers are coated on the surface of a ceramic-based pre-sintered body; wherein the innermost metal layer is made of titanium (melting point T). m1 The outermost metal layer has a melting point of 1668℃ and a thickness of 0.3mm; the outermost metal layer is made of molybdenum (melting point T). m2 (Temperature: 2623℃), thickness: 0.2mm;

[0169] The innermost metal layer is coated by spraying; the outermost metal layer is coated by using a thin-walled metal fitting method.

[0170] The ceramic-based presintered body is the ceramic-based presintered body provided in Preparation Example 4;

[0171] (b) At a pressure of 10 -3Vacuum sintering was carried out under conditions below Pa, with a vacuum sintering temperature T1 of 1668℃ and a holding time of 0.5h.

[0172] (c) Hot isostatic pressing was carried out under an argon atmosphere at a pressure of 200 MPa, a temperature T2 of 1630 °C, and a holding time of 1.5 h to obtain a submicron crystalline ceramic matrix composite material.

[0173] The submicron-sized ceramic matrix composite material obtained in this embodiment is fully sintered and dense, with a relative density of 100% and an average grain size of 0.849 μm.

[0174] Example 5

[0175] This embodiment provides a method for preparing submicron crystalline ceramic matrix composite materials, the method comprising the following steps:

[0176] (a) Two metal layers are coated on the surface of the ceramic-based pre-sintered body; wherein the innermost metal layer is made of zirconium-titanium alloy (melting point T). m1 The outermost metal layer is made of molybdenum (melting point T1800℃) and has a thickness of 0.3mm. m2 (Temperature: 2623℃), thickness: 0.2mm;

[0177] The innermost metal layer is coated by spraying; the outermost metal layer is coated by using a thin-walled metal fitting method.

[0178] The ceramic-based presintered body is the ceramic-based presintered body provided in Preparation Example 5;

[0179] (b) At a pressure of 10 -3 Vacuum sintering was carried out under conditions below Pa, with a vacuum sintering temperature T1 of 1800℃ and a holding time of 0.5h.

[0180] (c) Hot isostatic pressing was carried out under an argon atmosphere at a pressure of 170 MPa, a temperature T2 of 1760 °C, and a holding time of 1.5 h to obtain a submicron crystalline ceramic matrix composite material.

[0181] The submicron-sized ceramic matrix composite material obtained in this embodiment is fully sintered and dense, with a relative density of 100% and an average grain size of 0.783 μm.

[0182] Example 6

[0183] This embodiment provides a method for preparing submicron crystalline ceramic matrix composite materials, the method comprising the following steps:

[0184] (a) Two metal layers are coated on the surface of a ceramic-based pre-sintered body; wherein the innermost metal layer is made of zirconium (melting point T). m1The outermost metal layer is made of molybdenum (melting point T1852℃) and has a thickness of 0.3mm. m2 (Temperature: 2623℃), thickness: 0.2mm;

[0185] The ceramic-based presintered body is the ceramic-based presintered body provided in Preparation Example 6;

[0186] (b) At a pressure of 10 -3 Vacuum sintering was carried out under conditions below Pa, with a vacuum sintering temperature T1 of 1852℃ and a holding time of 0.5h.

[0187] (c) Hot isostatic pressing was carried out under an argon atmosphere at a pressure of 150 MPa, a temperature T2 of 1820 °C, and a holding time of 1.5 h to obtain a submicron crystalline ceramic matrix composite material.

[0188] The submicron-sized ceramic matrix composite material obtained in this embodiment is fully sintered and dense, with a relative density of 100% and an average grain size of 0.802 μm.

[0189] Example 7

[0190] This embodiment provides a method for preparing submicron crystalline ceramic matrix composite materials, the method comprising the following steps:

[0191] (a) Two metal layers are coated on the surface of the ceramic-based pre-sintered body; wherein the innermost metal layer is made of zirconium-cobalt alloy (melting point T). m1 The outermost metal layer has a melting point of 1668℃ and a thickness of 0.1mm; the outermost metal layer is made of niobium (melting point T). m2 (Temperature: 2468℃), thickness: 0.1mm;

[0192] The innermost metal layer is coated by spraying; the outermost metal layer is coated by using a thin-walled metal fitting method.

[0193] The ceramic-based presintered body is the ceramic-based presintered body provided in Preparation Example 4;

[0194] (b) At a pressure of 10 -3 Vacuum sintering was carried out under conditions below Pa, with a vacuum sintering temperature T1 of 1668℃ and a holding time of 0.5h.

[0195] (c) Hot isostatic pressing was carried out under an argon atmosphere at a pressure of 200 MPa, a temperature T2 of 1630 °C, and a holding time of 1.5 h to obtain a submicron crystalline ceramic matrix composite material.

[0196] Example 8

[0197] This embodiment provides a method for preparing submicron crystalline ceramic matrix composite materials, the method comprising the following steps:

[0198] (a) Two metal layers are coated on the surface of the ceramic-based pre-sintered body; wherein the innermost metal layer is made of titanium (melting point T). m1 The outermost metal layer has a melting point of 1668℃ and a thickness of 0.5mm; the outermost metal layer is made of tantalum (melting point T). m2 (Temperature: 2996℃), thickness: 0.3mm;

[0199] The innermost metal layer is coated by spraying; the outermost metal layer is coated by using a thin-walled metal fitting method.

[0200] The ceramic-based presintered body is the ceramic-based presintered body provided in Preparation Example 4;

[0201] (b) At a pressure of 10 -3 Vacuum sintering was carried out under conditions below Pa, with a vacuum sintering temperature T1 of 1668℃ and a holding time of 0.5h.

[0202] (c) Hot isostatic pressing was carried out under an argon atmosphere at a pressure of 200 MPa, a temperature T2 of 1630 °C, and a holding time of 1.5 h to obtain a submicron crystalline ceramic matrix composite material.

[0203] Comparative Example 1

[0204] This comparative example provides a method for preparing a submicron crystalline ceramic matrix composite material. Except that the ceramic matrix pre-sintered body is the same as the ceramic matrix pre-sintered body provided in Comparative Preparation Example 1, the rest are the same as in Examples 1-1.

[0205] In this comparative example, due to the high temperature of vacuum pre-sintering, the relative density of the ceramic-based pre-sintered body reached 93%, and the average grain size of the ceramic-based pre-sintered body also increased to 0.621 μm. Subsequently, during vacuum sintering and hot isostatic pressing, the sintered body was fully sintered and dense, with a relative density of 100%, but the grains further grew to 1.272 μm.

[0206] Comparative Example 2

[0207] This comparative example provides a method for preparing a submicron crystalline ceramic matrix composite material. Except that the ceramic matrix pre-sintered body is the same as the ceramic matrix pre-sintered body provided in Comparative Preparation Example 2, the rest are the same as in Examples 1-1.

[0208] Because the relative density of the ceramic matrix presintered body in this comparative example is low (69%), and it is entirely open-pore, it suffers from several drawbacks. Firstly, the presintered body has low strength, making it prone to edge and corner damage during further processing. Secondly, during vacuum sintering, the molten metal phase diffuses deeply into the presintered body through the pores, altering the material composition of the submicron-crystalline ceramic matrix composite and failing to meet the application requirements for molds, cutting tools, or wear-resistant parts.

[0209] Comparative Example 3

[0210] This comparative example provides a method for preparing a submicron crystalline ceramic matrix composite material, except that it is identical to Example 1-1 except that a 0.3 mm thick layer of metallic nickel is coated on the surface of the ceramic matrix pre-sintered body.

[0211] In this comparative example, since only one layer of metallic nickel is coated, during vacuum sintering, the molten nickel flows to the lower part of the product under the action of gravity, resulting in the upper part of the product not being properly sealed. Subsequently, hot isostatic pressing sintering cannot sinter the product into a dense state.

[0212] Comparative Example 4

[0213] This comparative example provides a method for preparing a submicron crystalline ceramic matrix composite material, except that it is identical to Example 1-1 except that a 0.3 mm thick titanium layer is coated on the surface of the ceramic matrix pre-sintered body.

[0214] In this comparative example, since only one layer of titanium metal is coated, and the temperature during vacuum sintering is lower than the melting point of the titanium layer, it cannot be melted. This results in the inability to seal the pre-sintered body through the melt sealing method, thus preventing the product from being sintered densely.

[0215] Comparative Example 5

[0216] This comparative example provides a method for preparing submicron crystalline ceramic matrix composite materials, which is the same as in Example 1-1 except that the vacuum sintering temperature T1 is 1485℃.

[0217] Since the temperature of vacuum sintering is much higher than the melting point of the innermost nickel layer, on the one hand, the diffusion capacity of the molten nickel liquid phase increases rapidly, resulting in an increase in the depth of diffusion along the pores into the ceramic matrix pre-sintered body, and the surface quality of the resulting submicron crystalline ceramic matrix composite material decreases; on the other hand, the increased temperature of vacuum sintering leads to grain growth, and the average grain size of the final submicron crystalline ceramic matrix composite material reaches 1.114 μm.

[0218] Comparative Example 6

[0219] This comparative example provides a method for preparing submicron crystalline ceramic matrix composite materials. Except for the hot isostatic pressing sintering temperature T2 of 1455℃, the rest is the same as in Example 1-1.

[0220] Compared with Examples 1-1, in this comparative example, the temperature of hot isostatic pressing (HIP) was increased to reach the melting point of the innermost metal layer. As a result, the innermost metal layer did not remain in a solid phase during HIP and melted. Under pressure, the molten liquid phase rapidly diffused into the interior along the pores of the ceramic matrix pre-sintered body. This led to an increase in the nickel content in the microstructure of the submicron crystalline ceramic matrix composite material at a certain depth from the surface after sintering. Within this depth range, the performance of the submicron crystalline ceramic matrix composite material decreased sharply and could not meet the application requirements of molds, cutting tools, or wear-resistant parts.

[0221] The average grain size and relative density of the submicron-crystalline ceramic matrix composites obtained in the above embodiments and comparative examples are shown in Tables 2 and 3. The average grain size was determined using scanning electron microscopy (SEM), and the relative density was determined using Archimedes' displacement method. The relative density of the obtained submicron-crystalline ceramic matrix composite is the ratio of the density of the obtained material to its theoretical density.

[0222] Table 2. Test parameters for each embodiment and comparative example

[0223]

[0224]

[0225] Table 3. Test results of each embodiment and comparative example

[0226]

[0227]

[0228] In summary, the preparation method provided by this invention achieves the densification of submicron-sized ceramic matrix composites at a lower temperature by coating the surface of the ceramic matrix pre-sintered body with at least two metal layers. This resolves the contradiction between higher temperatures promoting densification but leading to grain growth and lower temperatures inhibiting grain growth but resulting in less dense sintering. Ultimately, a submicron-sized ceramic matrix composite with an average grain size of submicron (less than 1 μm) and a relative density higher than 99.8% can be obtained. Furthermore, vacuum sintering and hot isostatic pressing are not limited by shape or size, enabling mass production. The submicron-sized ceramic matrix composite prepared by this invention has an average grain size of submicron and a relative density higher than 99.8%.

[0229] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a submicron crystalline ceramic matrix composite material, characterized in that, The preparation method includes the following steps: At least two metal layers are coated on the surface of the ceramic matrix pre-sintered body, and then vacuum sintering and hot isostatic pressing are performed in sequence to obtain the submicron crystalline ceramic matrix composite material. The relative density of the ceramic-based presintered body is 80% to 92%, and the average grain size of the ceramic-based presintered body is less than 0.6 μm; Of the at least two metal layers, the melting point T of the outermost metal layer is... m2 The melting point T is higher than that of the innermost metal layer. m1 And the vacuum sintering temperature T1; The melting point T of the innermost metal layer m1 The temperature T1 of the vacuum sintering is 0°C to 20°C lower than that of the vacuum sintering. In the at least two metal layers, the melting point of each metal layer is higher than the temperature T2 of hot isostatic pressing sintering; The thickness of the innermost metal layer is 0.1 mm to 0.5 mm; the thickness of the outermost metal layer is 0.1 mm to 0.3 mm. The vacuum sintering temperature T1 is from 1430°C to 1872°C; The temperature T2 of the hot isostatic pressing sintering is higher than the melting point T of the innermost metal layer. m1 The temperature is 10°C lower than or equal to 50°C; the temperature T2 of the hot isostatic pressing sintering is 1380°C to 1842°C.

2. The preparation method according to claim 1, characterized in that, The melting point T of the innermost metal layer m1 The temperature ranges from 1430℃ to 1852℃.

3. The preparation method according to claim 1, characterized in that, The material of the innermost metal layer includes any one or a combination of at least two of Ni, Co, Fe, Ti, or Zr.

4. The preparation method according to claim 1, characterized in that, The outermost metal layer is made of any one or a combination of at least two of Ti, Zr, Mo, Nb, or Ta.

5. The preparation method according to claim 1, characterized in that, The holding time for vacuum sintering is 0.5h to 1h.

6. The preparation method according to claim 1, characterized in that, The vacuum sintering is performed at a pressure of 10. -3 Perform below Pa.

7. The preparation method according to claim 1, characterized in that, The hot isostatic pressing sintering is carried out in an inert atmosphere.

8. The preparation method according to claim 1, characterized in that, The pressure for hot isostatic pressing is from 150 MPa to 300 MPa.

9. The preparation method according to claim 1, characterized in that, The holding time for hot isostatic pressing sintering is 1 hour to 3 hours.

10. The preparation method according to claim 1, characterized in that, The method for preparing the ceramic-based pre-sintered body includes sequential processes of powder mixing, molding, degreasing, and vacuum pre-sintering.

11. The preparation method according to claim 10, characterized in that, The vacuum pre-sintering temperature T3 is 1400℃ to 1910℃.

12. The preparation method according to claim 10, characterized in that, The holding time for vacuum pre-sintering is 1 to 3 hours.

13. The preparation method according to claim 10, characterized in that, The vacuum pre-sintering is carried out at a pressure below 30 Pa.

14. The preparation method according to claim 1, characterized in that, The submicron-crystalline ceramic matrix composite material includes any one of submicron-crystalline oxide ceramic matrix composite material, submicron-crystalline nitride ceramic matrix composite material, submicron-crystalline boride ceramic matrix composite material, or submicron-crystalline carbide ceramic matrix composite material.

15. The preparation method according to claim 14, characterized in that, The raw materials for preparing the submicron crystalline oxide ceramic matrix composite material, by volume percentage, include: more than 50 vol% of oxide ceramic matrix, less than 49.5 vol% of additives, and less than 0.5 vol% of sintering aid.

16. The preparation method according to claim 14, characterized in that, The raw materials for preparing the submicron crystalline nitride ceramic matrix composite material, by volume percentage, include: more than 50 vol% nitride ceramic matrix, less than 49.5 vol% additives, and less than 0.5 vol% sintering aids.

17. The preparation method according to claim 14, characterized in that, The raw materials for preparing the submicron crystalline boride ceramic matrix composite material, by volume percentage, include: more than 50 vol% boride ceramic matrix, less than 49.5 vol% additives, and less than 0.5 vol% sintering aids.

18. The preparation method according to claim 14, characterized in that, The raw materials for preparing the submicron crystalline carbide ceramic matrix composite material, by volume percentage, include: more than 50 vol% of carbide ceramic matrix, less than 49.5 vol% of additives, and less than 0.5 vol% of sintering aid.

19. A submicron-crystalline ceramic matrix composite material, characterized in that, The submicron crystalline ceramic matrix composite material is prepared by the preparation method according to any one of claims 1 to 18; The submicron crystalline ceramic matrix composite material has an average grain size of less than 1 μm and a relative density of more than 99.8%.

20. An application of a submicron crystalline ceramic matrix composite material, characterized in that, The submicron crystalline ceramic matrix composite material is used to prepare molds or cutting tools; The submicron crystalline ceramic matrix composite material is prepared by the preparation method according to any one of claims 1 to 18, or is the submicron crystalline ceramic matrix composite material according to claim 19.

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