A multiphase ceramic matrix composite material with a double-layer interface, its preparation method and application

Abstract

This invention discloses a multiphase ceramic matrix composite material with a double-layer interface, its preparation method, and its applications, relating to the field of ceramic matrix composite technology. The method involves sequentially coating the surface of Al2O3 whiskers with an interfacial layer of LaPO4 and Y2O3 to obtain Al2O3... 3W Prefabricated body; Al2O 3W A preform is embedded in Al-Y alloy powder, and after melt infiltration, it undergoes oxidation treatment in an air atmosphere to obtain a multiphase ceramic matrix composite material with a double-layer interface. The process provided by this invention has a short cycle time, high stability and reliability, and good engineering value, which is conducive to broadening the application fields of YAG-based composite materials.

Description

Technical Field

[0001] This invention relates to the field of ceramic matrix composites, specifically to a multiphase ceramic matrix composite material with a double-layer interface, its preparation method, and its application. Background Technology

[0002] In the aerospace field, the working environment of hot-end structural components such as engine exhaust nozzles is harsh, with high operating temperatures, severe environmental corrosion, and the need to withstand certain working stresses. Therefore, there is an urgent need for materials that combine excellent high-temperature resistance, resistance to water and oxygen corrosion, and good mechanical properties. To address this need, researchers have developed alumina fiber-reinforced oxide ceramic matrix composites. In this composite, the reinforcement is continuous alumina fibers, which exhibit a polycrystalline structure. The grain boundaries of polycrystalline materials are prone to slippage at high temperatures, leading to creep and a decrease in high-temperature mechanical properties. Another oxide composite reinforcement is alumina whiskers. Unlike the microstructure of alumina fibers, alumina whiskers have a single-crystal structure and higher thermal stability. Alumina whisker-reinforced oxide ceramic matrix composites show promise as a novel candidate material for hot-end structural components in engines.

[0003] Currently, research on the preparation technology of alumina whisker-reinforced oxide ceramic matrix composites mainly revolves around the sintering process. However, alumina materials inevitably suffer from sintering shrinkage during sintering. Researchers have studied the sintering shrinkage of alumina ceramics, revealing that the sintering temperature for alumina ceramics is around 1200℃. At this temperature, the bonding activity of alumina increases, leading to strong sintering between the alumina matrix and the reinforcement, resulting in significant volume changes (10%–20%), and even sample cracking during pressureless sintering. In existing technologies, when reinforcing fine-grained alumina ceramics with alumina whiskers, the excessively strong bond between the whiskers and the matrix makes it difficult for the whiskers to deflect cracks and pull out when the whisker volume fraction reaches 10%, resulting in insufficient strengthening and toughening, and consequently, poor mechanical properties of the composite material. Therefore, achieving near-net-shape molding of oxide ceramic matrix composites and controlling the strong interfacial bonding between oxide whiskers and the oxide matrix are pressing challenges that need to be addressed in this field.

[0004] In oxide ceramic matrix composites, the traditional alumina matrix has insufficient creep resistance, affecting the high-temperature long-term performance of the composites. Unlike the alumina matrix, the yttrium aluminum garnet (YAG) matrix has a special crystal structure, resulting in superior high-temperature creep resistance. In currently prepared Al2O3-YAG multiphase ceramics, the volume fraction of YAG is low (3-20%). In the Al2O3-YAG multiphase ceramics prepared by P. Palmero et al. (Creep behaviour of alumina / YAG composites prepared by different sintering routes,[J].Ceramics International,2012,38(1):433-441.), the YAG content was only 5 vol.%. In the Al2O3-YAG composite ceramic prepared by [Authors' Name] (Effect of YAG content on creep resistance and mechanical properties of Al2O3-YAG composite, [J]. Ceramics International, 46(18): 15998-6007.), the YAG content was 18 vol.%. The improvement of the high-temperature creep resistance of the material depends on the content inside the material, but there are currently no research reports on the introduction of YAG phase into ceramics with a content higher than 35 vol.%, which makes it difficult to improve the high-temperature creep resistance of the composite material.

[0005] In summary, current research primarily focuses on developing methods for preparing oxide whisker-reinforced oxide ceramic matrix composites using sintering technology. However, the significant shrinkage caused by sintering makes it difficult to control the material shape, hindering near-net-shape forming and requiring secondary processing. Furthermore, the strong bonding interface between the whiskers and the matrix impedes the whiskers' ability to exert their strengthening and toughening effects. Additionally, the low YAG content in the matrix limits the mechanical properties and high-temperature creep resistance of the resulting composites. Therefore, there is an urgent need to develop a rapid near-net-shape preparation method for oxide whisker-reinforced oxide ceramic matrix composites with controllable interfacial bonding between the reinforcement and the matrix and a high YAG matrix volume fraction. Summary of the Invention

[0006] To address the shortcomings of the aforementioned background technologies, this invention primarily targets problems such as excessive volume shrinkage during sintering, overly strong bonding between the reinforcement and matrix, and low volume fraction of the YAG phase in YAG-Al2O3 multiphase ceramics. This invention provides a multiphase ceramic matrix composite material with a double-layer interface, its preparation method, and its applications. This method features a short process cycle, high stability and reliability, and possesses significant engineering value, thus broadening the application fields of YAG-based composite materials.

[0007] The first objective of this invention is to provide a method for preparing a multiphase ceramic matrix composite material with a bilayer interface, comprising the following steps:

[0008] By sequentially coating the surface of Al2O3 whiskers with an interfacial layer of LaPO4 and Y2O3, Al2O3 is obtained. 3W Precast concrete;

[0009] Al2O 3W The preform is embedded in Al-Y alloy powder, and after melting and infiltration, it is oxidized in an air atmosphere to obtain a multiphase ceramic matrix composite material with a double-layer interface.

[0010] Preferably, the thickness of the LaPO4 interface layer sequentially coated on the surface of the Al2O3 whiskers is 10-200 nm, and the thickness of the Y2O3 interface layer is 20-250 nm.

[0011] Preferably, the melting and infiltration process includes: melting and infiltration in a vacuum environment, with a melting and infiltration heating rate of 10-15℃ / min, a melting and infiltration temperature of 1450-1520℃, and a melting and infiltration time of 2-3h.

[0012] Preferably, the oxidation treatment in air includes: heating the melt-infiltrated product to 900-950°C in air at a heating rate of 5-10°C / min and holding it at that temperature for 2-3 hours; then heating it to 1400-1450°C at a heating rate of 5-8°C / min and holding it at that temperature for 3-4 hours.

[0013] Preferably, an interface layer of LaPO4 is sequentially coated onto the surface of Al2O3 whiskers, comprising:

[0014] Al2O3 whiskers were dispersed in an aqueous solvent to obtain a suspension;

[0015] Add La(NO3)3 solution and Na3PO4 solution to the suspension, mix well, and obtain an emulsion;

[0016] After filtering and drying, the emulsion was calcined at 950–1200℃ for 1.5–3 h to obtain Al2O3 whiskers coated with a LaPO4 interface layer.

[0017] Preferably, the mass ratio of Al2O3 whiskers, La(NO3)3, Na3PO4 and water solvent in the emulsion is (48-64):28:11:(2400-3200).

[0018] Preferably, the Al2O 3W During the preparation of the preform, LaPO4 is coated onto the surface of Al2O3 whiskers to obtain Al2O3 whiskers with a LaPO4 interface layer, followed by a process of coating with a Y2O3 interface layer, including:

[0019] Y(NO3)3 and Al2O3 whiskers coated with LaPO4 interface layer were uniformly dispersed in an aqueous solvent to obtain a suspension;

[0020] After drying the suspension, it was calcined at 850–1200℃ for 1.5–3 hours to obtain Al2O. 3W Precast concrete;

[0021] The mass ratio of Y(NO3)3, Al2O3 whiskers coating the LaPO4 interface layer, and water solvent must be 21:(6~8):(300~400).

[0022] Preferably, the Al2O 3W During the preform preparation process, after sequentially coating the Al2O3 whisker surface with an interface layer of LaPO4 and Y2O3, the process also includes:

[0023] The product, which is sequentially coated with LaPO4 and Y2O3 interface layers on the surface of Al2O3 whiskers, is mixed with polymethyl methacrylate (PMMA) and then ground.

[0024] The ground powder was dry-pressed and then heat-treated in air at 1350–1550°C for 2–3 hours to obtain Al2O. 3W Precast concrete.

[0025] The second objective of this invention is to provide a multiphase ceramic matrix composite material with a double-layer interface.

[0026] The third objective of this invention is to provide an application of a multiphase ceramic matrix composite material with a double-layer interface in the hot-end structural components of an aero-engine.

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] This invention provides a multiphase ceramic matrix composite material with a double-layer interface, its preparation method, and its application. The method employs a liquid-phase approach, where Al2O3 whiskers (Al2O3...) are used... 3W The surface is uniformly coated with LaPO4 and Y2O3 interfacial layers sequentially. The formed Y2O3-LaPO4 bilayer coating structure is beneficial to Al2O3. 3WVolume control during the heat treatment strengthening process of the preform results in a volume change of only 2% to 4%, while avoiding significant sintering between whiskers during the heat treatment strengthening process.

[0029] The Al2O3 prepared by this invention has a surface coated with a Y2O3-LaPO4 bilayer interface. 3W After 4 hours of ball milling, there was no obvious damage, and the whisker structure showed good stability. This is mainly because: LaPO4 is a wear-resistant material, which can protect the whiskers, and the rough structure of the outer Y2O3 interface further enhances the protective effect. During the ball milling collision process, some rough surfaces can act as a buffer.

[0030] This invention employs a Y2O3-LaPO4 bilayer interface to coat Al2O 3W It can significantly improve Al2O 3W The wettability of the preform with the Al-Y alloy was utilized to prepare a high-density Al2O3. 3W / YAG-Al2O3 composite material is beneficial to the improvement of mechanical properties;

[0031] Al2O prepared by this invention 3W In the preform, Al2O 3W The volume fraction of Al2O3 is 35%–40%, which ensures that both the preform and the final composite material have high stiffness and strength. At this volume fraction, Al2O3... 3W A unique secondary porous structure was formed within the preform, with uniformly distributed, through-pores ranging in size from 5 to 8 μm. This structure facilitates the subsequent melting and infiltration of the Al-Y alloy. Abaqus finite element simulations show that after melting and infiltration, Al2O3… 3W The stress within / Al-Y is low, which avoids stress concentration that could lead to cracking and deformation of the precast structure.

[0032] Al2O prepared by this invention 3W Precast molding methods are not limited to dry pressing; the molding process is flexible.

[0033] This invention relates to Al2O containing a Y2O3-LaPO4 bilayer interface. 3W Pre-embedded Al-Y alloy powder is used. After Al-Y alloy melts and infiltrates, it does not solidify into lumps, but remains loose, similar to clumps of sand, making sampling convenient.

[0034] Al2O obtained after alloy melting and infiltration in this invention 3WThe presence of porosity in Al-Y alloys facilitates subsequent oxidation processes and controls oxidation volume expansion. The Al-Y alloy oxidation reaction is thorough, leaving no alloy residue and producing a high-content YAG matrix (YAG: 37.02%–40.11% by volume, Al2O3: 22.8%–24.89% by volume). Literature indicates that Al2O3 exhibits a creep rate of 10⁻⁶ at 1400℃ and 50 MPa stress. -5 The Al2O prepared by this invention is approximately / s. 3W The YAG-Al2O3 composite material exhibits a creep rate of 2.08 × 10⁻⁶ under stress conditions of 1400℃ and 60 MPa. -6 It exhibits excellent creep resistance at approximately / s.

[0035] Al2O prepared by this invention 3W In YAG-Al2O3 composite materials, the Y2O3-LaPO4 bilayer interface regulates the bonding state between the reinforcement and the matrix, resulting in a synergistic toughening effect. Attached Figure Description

[0036] Figure 1 This is a process flow diagram of the present invention;

[0037] Figure 2 It is the Al2O prepared in Example 1 of this invention. 3W Macroscopic view of prefabricated structure;

[0038] Figure 3 These are TEM images of the LaPO4-coated interface and the LaPO4 and Y2O3-coated interface prepared in Example 3 of this invention;

[0039] Figure 4 This is the TEM diffraction pattern at the Y2O3-LaPO4 interface after whisker coating in Example 3;

[0040] Figure 5 This is a microscopic image of the sample after Al-Y alloy melting and infiltration in Example 3 of the present invention;

[0041] Figure 6 These are macroscopic and microscopic SEM images of the oxidized composite material in Example 3 of this invention;

[0042] Figure 7 The material in Comparative Example 2 that was not infiltrated with Al-Y alloy;

[0043] Figure 8 The image shows the SEM image of the damaged whisker material without LaPO4 coating in Comparative Example 3.

[0044] Figure 9 These are simulation diagrams of stress (a) and strain (b) of the material state during the melting and infiltration process in Example 2;

[0045] Figure 10 This is a comparison of the melt infiltration of three groups of preforms, namely Example 2 and Comparative Examples 1 and 2;

[0046] Figure 11 This is a mercury intrusion porosimetry diagram of the secondary pore structure in Example 2;

[0047] Figure 12 This is a sample image of the alloy after efflux in Comparative Example 6;

[0048] Figure 13 This is a graph showing the creep test time and displacement in Example 3; Detailed Implementation

[0049] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below in conjunction with specific embodiments and accompanying drawings. However, the embodiments described are not intended to limit the present invention.

[0050] This invention addresses the problems of excessive volume shrinkage in current sintering processes, overly strong bonding between the reinforcement and matrix, and low volume fraction of the YAG phase in YAG-Al2O3 multiphase ceramics. It provides a method for preparing a multiphase ceramic matrix composite material with a double-layer interface, specifically based on a metal infiltration combined with oxidation process to prepare Al2O3 containing a Y2O3-LaPO4 double-interface layer. 3W / YAG-Al2O3 multiphase ceramic matrix composite material.

[0051] The first aspect of this invention provides a method for preparing a multiphase ceramic matrix composite material containing a double-layer interface, comprising the following steps:

[0052] In Al2O3 whiskers (Al2O 3W The surface is sequentially coated with an interfacial layer of LaPO4 and Y2O3 to obtain Al2O 3W Precast concrete;

[0053] Al2O 3W The preform is embedded in Al-Y alloy powder, and after melting and infiltration, it is oxidized in an air atmosphere to obtain a multiphase ceramic matrix composite material with a double-layer interface.

[0054] This invention involves first preparing a LaPO4 interface on the surface of Al2O3 whiskers, followed by preparing a Y2O3 interface. The LaPO4 interface protects the Al2O3... 3W Its function is to prevent the alloy from reacting with Al2O during the alloy infiltration process. 3W The reaction facilitates interfacial debonding during composite material failure; the Y2O3 interface allows the Al-Y alloy to react within the Al2O3 layer. 3WThe wetting effect in the whisker preform is better. The outer layer of LaPO4 is to allow the alloy to react with yttrium oxide during the alloy immersion process. At the same time, a relatively dense YAG will be formed at the contact part between Y2O3 and the alloy.

[0055] Among them, the thickness of the LaPO4 interface layer sequentially coated on the surface of Al2O3 whiskers is 10-200 nm, and the thickness of the Y2O3 interface layer is 20-250 nm.

[0056] According to the present invention, the melting and infiltration process includes: melting and infiltration in a vacuum environment, with a melting and infiltration heating rate of 10-15℃ / min, a melting and infiltration temperature of 1450-1520℃, and a melting and infiltration time of 2-3h.

[0057] The oxidation treatment in air includes: heating the melt-infiltrated product to 900-950°C in air at a heating rate of 5-10°C / min and holding it at that temperature for 2-3 hours; then heating it to 1400-1450°C at a heating rate of 5-8°C / min and holding it at that temperature for 3-4 hours.

[0058] Specifically, an interface layer of LaPO4 is sequentially coated onto the surface of Al2O3 whiskers, including:

[0059] Al2O3 whiskers were dispersed in an aqueous solvent to obtain a suspension;

[0060] Add La(NO3)3 solution and Na3PO4 solution to the suspension, mix well, and obtain an emulsion;

[0061] After filtering and drying, the emulsion was calcined at 950–1200℃ for 1.5–3 h to obtain Al2O3 whiskers coated with a LaPO4 interface layer.

[0062] In the emulsion, the mass ratio of Al2O3 whiskers, La(NO3)3, Na3PO4 and water solvent is (48-64):28:11:(2400-3200).

[0063] According to the present invention, the Al2O 3W During the preparation of the preform, LaPO4 is coated onto the surface of Al2O3 whiskers to obtain Al2O3 whiskers with a LaPO4 interface layer, followed by a process of coating with a Y2O3 interface layer, including:

[0064] Y(NO3)3 and Al2O3 whiskers coated with LaPO4 interface layer were uniformly dispersed in an aqueous solvent to obtain a suspension;

[0065] After drying the suspension, it was calcined at 850–1200℃ for 1.5–3 hours to obtain Al2O. 3W Precast concrete.

[0066] The mass ratio of Y(NO3)3, Al2O3 whiskers coating the LaPO4 interface layer, and water solvent must be 21:(6~8):(300~400).

[0067] Wherein, Al2O 3W During the preform preparation process, after sequentially coating the Al2O3 whisker surface with an interface layer of LaPO4 and Y2O3, the process also includes:

[0068] The product, in which LaPO4 and Y2O3 interface layers are sequentially coated on the surface of Al2O3 whiskers, is mixed with PMMA and then ground.

[0069] The ground powder was dry-pressed and then heat-treated in air at 1350–1550°C for 2–3 hours to obtain Al2O. 3W Precast concrete.

[0070] See Figure 1 The method shown includes: a method for preparing a multiphase ceramic matrix composite material with a double-layer interface, comprising:

[0071] Step (1) Coating of the LaPO4 interface: Deionized water (H2O) and Al2O 3W The two mixtures are then magnetically stirred for 0.5–1.5 hours to obtain a suspension.

[0072] Prepare a 0.5–1 mol / L La(NO3)3 solution and inject it uniformly into the whisker suspension using a syringe pump at a rate of 0.2–2 mL / s. During the injection process, perform magnetic stirring. After the injection is complete, perform magnetic stirring for 0.5–1 h. Then, inject a 0.5–1 mol / L Na3PO4 solution uniformly using a syringe pump at a rate of 0.2–2 mL / s. During the injection process, perform magnetic stirring for 1.5–3.5 h. This will yield an emulsion.

[0073] The obtained emulsion was filtered to obtain a block with a water content ≤10%. The block with a water content ≤10% was dried at 80-100℃ for 8-12 hours, and finally calcined at 950-1200℃ for 2 hours and pulverized to obtain Al2O coated with LaPO4 interface. 3W In the emulsion, Al2O 3W The mass ratio of La(NO3)3, Na3PO4 and H2O is (48-64):28:11:(2400-3200); the heating rate during the calcination process is 5-10℃ / min.

[0074] Step (2) Coating of the Y2O3 interface: Y(NO3)3 and Al2O3 coating the LaPO4 interface are coated. 3WThe mixture is prepared by mixing with H2O to obtain a suspension. The suspension is then ultrasonically vibrated in a water bath at 10–20°C for 10–20 min, followed by magnetic stirring for 2–3 h. Subsequently, it is dried at 120–150°C to obtain a bulk material. The bulk material is then pulverized, and the pulverized powder is calcined at 850–1200°C for 2 h to obtain Al2O3 coated with a Y2O3-LaPO4 bilayer interface. 3W The Y(NO3)3 and LaPO4 coated Al2O 3W In H2O, the mass ratio of each phase is 21:(6~8):(300~400); during the calcination process, the heating rate is 5~10℃ / min.

[0075] Step (3) Al2O 3W Preparation of the preform: Weigh Al2O3 coated with the Y2O3-LaPO4 bilayer interface. 3W The powder is ball-milled with PMMA at a mass ratio of 20:(3-4) for 2-3 hours at a speed of 180-250 r / min.

[0076] The ball-milled powder was dry-pressed at a pressure of 100–150 MPa for 2–5 min. After demolding, it was heat-treated in air at a temperature of 1350–1550 °C for 2–3 h to obtain Al2O3 coated with a Y2O3-LaPO4 bilayer interface. 3W Precast concrete;

[0077] During the ball milling process, Al2O3 coated with a Y2O3-LaPO4 double-layer interface 3W The mass ratio of the ball milling beads to the grinding beads is 1:(8-15);

[0078] Step (4) Al-Y alloy infiltration: Al2O 3W The preform was embedded in Al-Y alloy powder and melt-infiltrated under vacuum. The melting infiltration heating rate was 10–15 °C / min, the melting infiltration temperature was 1450–1520 °C, and the melting infiltration time was 2–3 h. This process achieved Al-Y alloy in Al2O3 containing a Y2O3-LaPO4 bilayer interface. 3W Sufficient penetration into the precast structure;

[0079] Step (5) Al-Y alloy oxidation: The preform filled with Al-Y alloy obtained in step (4) is oxidized in an air atmosphere. First, the temperature is increased to 900-950℃ at a heating rate of 5-10℃ / min and held for 2-3 hours. Then, the temperature is increased to 1400-1450℃ at a heating rate of 5-8℃ / min and held for 3-4 hours to generate a YAG-Al2O3 matrix, thereby obtaining Al2O3. 3W / YAG-Al2O3 composite material is a multiphase ceramic matrix composite material with a double-layer interface.

[0080] The reaction occurs at 1400–1450℃: Al2O3 + Y2O3 → YAG.

[0081] In steps (1) and (2), the LaPO4 interface must be coated first, followed by the Y2O3 interface. The thickness of the LaPO4 interface can be 10-200 nm, and the thickness of the Y2O3 interface can be 20-250 nm.

[0082] In step (1) of preparing the LaPO4 interface, rapid stirring is to prevent the LaPO4 from agglomerating during the preparation of the LaPO4 interface, which would result in poor coating effect. After the Na3PO4 solution is injected, the rotation speed is reduced to ensure that the LaPO4 coating is uniform and stable, and to prevent the formed LaPO4 from peeling off during the coating process.

[0083] The ratio of PMMA diameter to whisker length used in step (3) must be between 1:(1.2 to 1.4). If the ratio is too large, it will cause the pore channels to accumulate large pores, resulting in excessively large pores and a bulky, uneven distribution of the matrix, which will lead to poor mechanical properties of the composite material. If the ratio is too small, it will cause the pore channels to be too small, resulting in poor alloy melting and infiltration, causing surface sealing. At the same time, it will cause the secondary pore structure formed by whisker overlap and pore-forming agent to be indistinct, resulting in excessive alloy filling, which is not conducive to oxidation expansion and oxygen transport.

[0084] In step (4), the mass ratio of PMMA to whiskers is in the range of 20:(3~4). The Abaqus software is used to simulate this melting and infiltration state. Under this state, the stress distribution is relatively good, and the volume fraction of the reinforcement is high. If it is too low, the skeleton formed by the whiskers will be destroyed during the melting and infiltration or oxidation process. If it is too high, the interior will be too dense and the alloy melting and infiltration effect will be poor.

[0085] In step (5), due to the presence of the Y2O3 interface, the Al2O3 on the surface of the Al-Y alloy will be consumed to generate YAG. At the same time, the Y2O3 and Al2O3 after the alloy is oxidized at 900℃ will react at 1450℃, and the broken part of the Y2O3 and Al2O3 at 900℃ will continue to generate the YAG matrix.

[0086] In step (5), the alloy melting and infiltration must follow the order of oxidation followed by reaction. The oxidation temperature must be between 900 and 950°C. Since the melting point of the alloy is around 1000°C, an excessively low oxidation temperature will cause the alloy on the macroscopic surface of the material to be completely oxidized, and the surface will become dense. Oxygen will not be able to continue to enter the interior along the pore channels to cause further oxidation. An excessively high oxidation temperature will cause the surface alloy to be oxidized too little, and the Al-Y alloy will not be oxidized and will directly become molten and flow out. The temperature range of 900 to 950°C ensures that the Al-Y alloy can be completely oxidized and will not flow out.

[0087] A second aspect of this invention provides a multiphase ceramic matrix composite material containing a bilayer interface. It should be noted that the bilayer interface refers to a Y₂O₃ and LaPO₄ bilayer interface, and the multiphase ceramic refers to...

[0088] Al2O 3W / YAG-Al2O3.

[0089] The third aspect of this invention provides an application of a multiphase ceramic matrix composite material with a double-layer interface in the hot-end structural components of an aero-engine.

[0090] It should be noted that, unless otherwise specified, the experimental methods used in this invention are all conventional methods; and the reagents and materials used, unless otherwise specified, are all commercially available.

[0091] The Al-Y alloy powder used in the following examples was purchased from Wuxi Taicheng Metal, with a particle size of 500 mesh and a mass ratio of Al to Y of 7:3.

[0092] The Al2O3 whiskers used in the following examples were prepared according to the following steps:

[0093] Weigh the raw materials: 24g urea, 10.5g PEG400 (polyethylene glycol 400), 50.1ml aluminum sulfate, 132ml water;

[0094] After mixing the raw materials evenly, stir magnetically for 15-20 minutes, and then put them into a polytetrafluoroethylene container.

[0095] The polytetrafluoroethylene container was placed in a hydrothermal autoclave and then placed in a hydrothermal oven and heated to 120°C for 1440 min at a heating rate of 4°C / min. After the heating was completed, the solid was removed and centrifuged and washed three times, with each centrifugation speed of 3000 r / min for 10 min. Then it was dried at 100°C for 12 h and finally calcined at 1350°C for 2 h to obtain Al2O3 whiskers. The aspect ratio of the obtained Al2O3 whiskers was 10-20.

[0096] Example 1

[0097] A method for preparing a multiphase ceramic matrix composite material with a double-layer interface includes the following steps:

[0098] Step (1) Coating of the LaPO4 interface: Deionized water (H2O) and Al2O 3W The two mixtures were then magnetically stirred for 1 hour to obtain a suspension.

[0099] A 0.8 mol / L La(NO3)3 solution was prepared and uniformly injected into the whisker suspension at a rate of 0.5 mL / s using a syringe pump. Magnetic stirring was performed during the injection process. After injection, magnetic stirring was performed for 1 hour. Then, a 0.8 mol / L Na3PO4 solution was uniformly injected at a rate of 0.5 mL / s using a syringe pump. Magnetic stirring was performed during the injection process. After injection, magnetic stirring was performed for 2 hours to obtain an emulsion.

[0100] The obtained emulsion was filtered to obtain a block with a water content ≤10%. The block with a water content ≤10% was dried at 80-100℃ for 8-12 hours, and finally calcined at 950℃ for 2 hours and pulverized to obtain Al2O coated with LaPO4 interface. 3W ;

[0101] In emulsions, Al2O 3W The mass ratio of La(NO3)3, Na3PO4 and H2O is 55:28:11:2800;

[0102] During the calcination process, the heating rate is 10℃ / min;

[0103] Step (2) Coating of the Y2O3 interface: Y(NO3)3 and Al2O3 coating the LaPO4 interface are coated. 3W The mixture was prepared by mixing with H2O to obtain a suspension. The suspension was ultrasonically vibrated in a water bath at 20°C for 15 minutes, followed by magnetic stirring for 2.5 hours. The suspension was then dried at 140°C to obtain a block. The block was pulverized, and the pulverized powder was calcined at 950°C for 2 hours to obtain Al2O3 coated with a Y2O3-LaPO4 double-layer interface. 3W ;

[0104] Y(NO3)3 and LaPO4 coating Al2O 3W The mass ratio of water to deionized water is 21:7:350;

[0105] During the calcination process, the heating rate is 10℃ / min.

[0106] Step (3) Al2O 3W Preparation of the preform: Weigh Al2O3 coated with the Y2O3-LaPO4 bilayer interface. 3WThe powder was ball-milled for 2.5 hours at a speed of 200 r / min with PMMA in a mass ratio of 20:3.5.

[0107] The ball-milled powder was dry-pressed at a pressure of 120 MPa for 5 minutes. After demolding, it was subjected to heat treatment in air at 1500℃ for 2 hours to obtain Al2O3 coated with a Y2O3-LaPO4 bilayer interface. 3W Precast concrete;

[0108] During ball milling, Al2O3 coated with a Y2O3-LaPO4 double-layer interface 3W The mass ratio of the grinding beads to the ball bearings is 1:12;

[0109] Step (4) Al-Y alloy infiltration: Al2O 3W The preform was embedded in Al-Y alloy powder and melt-infiltrated under vacuum. The melting infiltration heating rate was 10℃ / min, the melting infiltration temperature was 1500℃, and the melting infiltration time was 2h. This achieved Al-Y alloy in Al2O3 containing a Y2O3-LaPO4 bilayer interface. 3W Sufficient penetration into the precast structure;

[0110] Step (5) Al-Y alloy oxidation: The preform filled with Al-Y alloy obtained in step (2) was oxidized in an air atmosphere. First, the temperature was increased to 900℃ at a heating rate of 10℃ / min and held for 2.5h. Then, the temperature was increased to 1400℃ at a heating rate of 5℃ / min and held for 3.5h to generate a YAG-Al2O3 matrix, thereby obtaining Al2O3. 3W / YAG-Al2O3 composite material.

[0111] The prepared preform is shown in the attached figure. Figure 2 Al2O provided in this embodiment 3W Macroscopic view of the preform, and the final Al2O2 prepared. 3W The porosity of the YAG-Al2O3 composite material is 28.61%, the oxidation rate is 97.28%, and the flexural strength is 114.79 MPa. Due to insufficient oxidation reaction temperature, the oxidation process is incomplete, resulting in a high porosity and low strength in the final composite material.

[0112] Example 2

[0113] A method for preparing a multiphase ceramic matrix composite material with a double-layer interface includes the following steps:

[0114] Step (1) Coating of the LaPO4 interface: Deionized water (H2O) and Al2O 3W The two mixtures were then magnetically stirred for 1 hour to obtain a suspension.

[0115] A 0.8 mol / L La(NO3)3 solution was prepared and uniformly injected into the whisker suspension at a rate of 0.5 mL / s using a syringe pump. Magnetic stirring was performed during the injection process. After injection, magnetic stirring was performed for 1 hour. Then, a 0.8 mol / L Na3PO4 solution was uniformly injected at a rate of 0.5 mL / s using a syringe pump. Magnetic stirring was performed during the injection process. After injection, magnetic stirring was performed for 2 hours to obtain an emulsion.

[0116] The obtained emulsion was filtered to obtain a block with a water content ≤10%. The block with a water content ≤10% was dried at 80-100℃ for 8-12 hours, and finally calcined at 950℃ for 2 hours and pulverized to obtain Al2O coated with LaPO4 interface. 3W ;

[0117] In emulsions, Al2O 3W The mass ratio of La(NO3)3, Na3PO4 and H2O is 55:28:11:2800;

[0118] During the calcination process, the heating rate is 10℃ / min;

[0119] Step (2) Coating of the Y2O3 interface: Y(NO3)3 and Al2O3 coating the LaPO4 interface are coated. 3W The mixture was prepared by mixing with H2O to obtain a suspension. The suspension was ultrasonically vibrated in a water bath at 20°C for 15 minutes, followed by magnetic stirring for 2.5 hours. The suspension was then dried at 140°C to obtain a block. The block was pulverized, and the pulverized powder was calcined at 950°C for 2 hours to obtain Al2O3 coated with a Y2O3-LaPO4 double-layer interface. 3W ;

[0120] Y(NO3)3 and LaPO4 coating Al2O 3W The mass ratio of water to deionized water is 21:7:350;

[0121] During the calcination process, the heating rate is 10℃ / min.

[0122] Step (3) Al2O 3W Preparation of the preform: Weigh Al2O3 coated with the Y2O3-LaPO4 bilayer interface. 3W The powder was ball-milled for 2.5 hours at a speed of 200 r / min with PMMA in a mass ratio of 20:3.5.

[0123] The ball-milled powder was dry-pressed at a pressure of 120 MPa for 5 minutes. After demolding, it was subjected to heat treatment in air at 1500℃ for 2 hours to obtain Al2O3 coated with a Y2O3-LaPO4 bilayer interface. 3W Precast concrete;

[0124] During ball milling, Al2O3 coated with a Y2O3-LaPO4 double-layer interface 3W The mass ratio of the grinding beads to the ball bearings is 1:12;

[0125] Step (4) Al-Y alloy infiltration: Al2O 3W The preform was embedded in Al-Y alloy powder and melt-infiltrated under vacuum. The melting infiltration heating rate was 10℃ / min, the melting infiltration temperature was 1500℃, and the melting infiltration time was 2h. This achieved Al-Y alloy in Al2O3 containing a Y2O3-LaPO4 bilayer interface. 3W Sufficient penetration into the precast structure;

[0126] Step (5) Al-Y alloy oxidation: The preform filled with Al-Y alloy obtained in step (2) was oxidized in an air atmosphere. First, the temperature was increased to 920℃ at a heating rate of 10℃ / min and held for 2.5h. Then, the temperature was increased to 1400℃ at a heating rate of 5℃ / min and held for 3.5h to generate a YAG-Al2O3 matrix, thereby obtaining Al2O3. 3W / YAG-Al2O3 composite material.

[0127] In this embodiment, the oxidation temperature was changed and increased by 20°C, resulting in the final Al2O2O2. 3W The porosity of the / YAG-Al2O3 composite material is 16.82%, the oxidation rate is 98.26%, and the flexural strength is 146.41 MPa. Due to the increased oxidation temperature, the Al-Y alloy is oxidized more fully and the oxidation effect is better. The internal matrix filling effect is improved, and the mechanical properties are improved compared with Example 1.

[0128] Example 3

[0129] A method for preparing a multiphase ceramic matrix composite material with a double-layer interface includes the following steps:

[0130] Step (1) Coating of the LaPO4 interface: Deionized water (H2O) and Al2O 3W The two mixtures were then magnetically stirred for 1 hour to obtain a suspension.

[0131] A 0.8 mol / L La(NO3)3 solution was prepared and uniformly injected into the whisker suspension at a rate of 0.5 mL / s using a syringe pump. Magnetic stirring was performed during the injection process. After injection, magnetic stirring was performed for 1 hour. Then, a 0.8 mol / L Na3PO4 solution was uniformly injected at a rate of 0.5 mL / s using a syringe pump. Magnetic stirring was performed during the injection process. After injection, magnetic stirring was performed for 2 hours to obtain an emulsion.

[0132] The obtained emulsion was filtered to obtain a block with a water content ≤10%. The block with a water content ≤10% was dried at 80-100℃ for 8-12 hours, and finally calcined at 950℃ for 2 hours and pulverized to obtain Al2O coated with LaPO4 interface. 3W ;

[0133] In emulsions, Al2O 3W The mass ratio of La(NO3)3, Na3PO4 and H2O is 55:28:11:2800;

[0134] During the calcination process, the heating rate is 10℃ / min;

[0135] Step (2) Coating of the Y2O3 interface: Y(NO3)3 and Al2O3 coating the LaPO4 interface are coated. 3W The mixture was prepared by mixing with H2O to obtain a suspension. The suspension was ultrasonically vibrated in a water bath at 20°C for 15 minutes, followed by magnetic stirring for 2.5 hours. The suspension was then dried at 140°C to obtain a block. The block was pulverized, and the pulverized powder was calcined at 950°C for 2 hours to obtain Al2O3 coated with a Y2O3-LaPO4 double-layer interface. 3W ;

[0136] Y(NO3)3 and LaPO4 coating Al2O 3W The mass ratio of water to deionized water is 21:7:350;

[0137] During the calcination process, the heating rate is 10℃ / min.

[0138] Step (3) Al2O 3W Preparation of the preform: Weigh Al2O3 coated with the Y2O3-LaPO4 bilayer interface. 3W The powder was ball-milled for 2.5 hours at a speed of 200 r / min with PMMA in a mass ratio of 20:3.5.

[0139] The ball-milled powder was dry-pressed at a pressure of 120 MPa for 5 minutes. After demolding, it was subjected to heat treatment in air at 1500℃ for 2 hours to obtain Al2O3 coated with a Y2O3-LaPO4 bilayer interface.3W Precast concrete;

[0140] During ball milling, Al2O3 coated with a Y2O3-LaPO4 double-layer interface 3W The mass ratio of the grinding beads to the ball bearings is 1:12;

[0141] Step (4) Al-Y alloy infiltration: Al2O 3W The preform was embedded in Al-Y alloy powder and melt-infiltrated under vacuum. The melting infiltration heating rate was 10℃ / min, the melting infiltration temperature was 1500℃, and the melting infiltration time was 2h. This achieved Al-Y alloy in Al2O3 containing a Y2O3-LaPO4 bilayer interface. 3W Sufficient penetration into the precast structure;

[0142] Step (5) Al-Y alloy oxidation: The preform filled with Al-Y alloy obtained in step (2) was oxidized in an air atmosphere. First, the temperature was increased to 900℃ at a heating rate of 10℃ / min and held for 2.5h. Then, the temperature was increased to 1420℃ at a heating rate of 5℃ / min and held for 3.5h to generate a YAG-Al2O3 matrix, thereby obtaining Al2O3. 3W / YAG-Al2O3 composite material.

[0143] Compared to Example 2, the reaction temperature in this embodiment was increased by 20°C. The whisker coating in this embodiment was observed, as shown in the attached figure. Figure 3 and attached Figure 4 ,in, Figure 3 The images shown are TEM images (a) of the LaPO4 interface after coating in Example 3, and TEM images (b) of the LaPO4 and Y2O3 interface. Figure 4 Examples 3 show the TEM (a) and diffraction pattern (b) at the Y₂O₃-LaPO₄ interface after whisker coating; Figure 3 , 4 It can be seen that the interface is evenly and completely covered by the outer layer, and at the same time... Figure 4 (b) shows that the diffraction pattern of the interface is clearly layered.

[0144] Meanwhile, the attached images show the infiltration-treated sample and the final sample. Figure 5 and 6 , Figure 5 Example 3: Microscopic image of the sample after Al-Y alloy melting and infiltration; Figure 6 Example 3 shows macroscopic and microscopic SEM images of the final composite material after oxidation, demonstrating its good coating effect. The final prepared Al2O 3W The flexural strength of the YAG-Al2O3 composite material is 284.47 MPa, which is a significant improvement. The porosity is about 8%, but it can still be further reduced to improve the mechanical properties.

[0145] Comparative Example 1

[0146] Step (1) Al2O 3W Preparation of the preform: Weigh out the interface-free Al2O 3W The powder was ball-milled for 2.5 hours at a speed of 200 r / min with PMMA in a mass ratio of 20:3.5.

[0147] The ball-milled powder was dry-pressed at a pressure of 120 MPa for 5 minutes. After demolding, it was subjected to heat treatment in air at 1500℃ for 2 hours to obtain Al2O3 coated with a Y2O3-LaPO4 bilayer interface. 3W Precast concrete;

[0148] During ball milling, Al2O3 coated with a Y2O3-LaPO4 double-layer interface 3W The mass ratio of the grinding beads to the ball bearings is 1:12;

[0149] Step (2) Al-Y alloy infiltration: Al2O 3W The preform was embedded in Al-Y alloy powder and melt-infiltrated under vacuum. The melting infiltration heating rate was 10℃ / min, the melting infiltration temperature was 1500℃, and the melting infiltration time was 2h. This achieved Al-Y alloy in Al2O3 containing a Y2O3-LaPO4 bilayer interface. 3W Sufficient penetration into the precast structure;

[0150] This comparative example did not include the coating of the LaPO4 and Y2O3 interfaces. Figure 7 As a comparative example, the preform without alloy infiltration in Al-Y alloy had poor wetting properties, resulting in alloy infiltration failure. The sample contained virtually no alloy, and the whiskers were not protected by LaPO4, causing them to be damaged.

[0151] Comparative Example 2

[0152] Step (1) Coating of the LaPO4 interface: Deionized water (H2O) and Al2O 3W The two mixtures were then magnetically stirred for 1 hour to obtain a suspension.

[0153] A 0.8 mol / L La(NO3)3 solution was prepared and uniformly injected into the whisker suspension at a rate of 0.5 mL / s using a syringe pump. Magnetic stirring was performed during the injection process. After injection, magnetic stirring was performed for 1 hour. Then, a 0.8 mol / L Na3PO4 solution was uniformly injected at a rate of 0.5 mL / s using a syringe pump. Magnetic stirring was performed during the injection process. After injection, magnetic stirring was performed for 2 hours to obtain an emulsion.

[0154] The obtained emulsion was filtered to obtain a block with a water content ≤10%. The block with a water content ≤10% was dried at 80-100℃ for 8-12 hours, and finally calcined at 950℃ for 2 hours and pulverized to obtain Al2O coated with LaPO4 interface. 3W ;

[0155] In emulsions, Al2O 3W The mass ratio of La(NO3)3, Na3PO4 and H2O is 55:28:11:2800;

[0156] During the calcination process, the heating rate is 10℃ / min;

[0157] Step (2) Al2O 3W Preparation of the preform: Weigh Al2O3 coated with the LaPO4 bilayer interface. 3W The powder was ball-milled for 2.5 hours at a speed of 200 r / min with PMMA in a mass ratio of 20:3.5.

[0158] The ball-milled powder was dry-pressed at a pressure of 120 MPa for 5 minutes. After demolding, it was subjected to heat treatment in air at 1500℃ for 2 hours to obtain Al2O3 coated with a Y2O3-LaPO4 bilayer interface. 3W Precast concrete;

[0159] During ball milling, Al2O3 coated with a Y2O3-LaPO4 double-layer interface 3W The mass ratio of the grinding beads to the ball bearings is 1:12;

[0160] Step (3) Al-Y alloy infiltration: Al2O 3W The preform was embedded in Al-Y alloy powder and melt-infiltrated under vacuum. The melting infiltration heating rate was 10℃ / min, the melting infiltration temperature was 1500℃, and the melting infiltration time was 2h. This achieved Al-Y alloy in Al2O3 containing a Y2O3-LaPO4 bilayer interface. 3W Sufficient penetration into the precast structure;

[0161] This comparative example did not involve coating the Y2O3 interface, resulting in failed melt infiltration and virtually no Al-Y alloy penetrating into the preform. (See attached image) Figure 8 As shown, Figure 8 Comparative Example 2: SEM image of the damaged whisker material without lanthanum phosphate coating. Figure 8 In (a), some whiskers remain intact, but there are many internal pores. Figure 8(b) The whiskers are clearly exposed and most of them are damaged. After subsequent oxidation and reaction, the mass increase is only 0.01g. Finally, SEM observation of its microstructure revealed that there are still many pores inside, indicating that melting and infiltration cannot occur without a Y2O3 interface.

[0162] Comparative Example 3

[0163] Step (1) Coating of the Y2O3 interface: Y(NO3)3 and Al2O3 coating the LaPO4 interface are coated together. 3W The mixture was prepared by mixing with H2O to obtain a suspension. The suspension was ultrasonically vibrated in a water bath at 20°C for 15 minutes, followed by magnetic stirring for 2.5 hours. The suspension was then dried at 140°C to obtain a block. The block was pulverized, and the pulverized powder was calcined at 950°C for 2 hours to obtain Al2O3 coated with a Y2O3-LaPO4 double-layer interface. 3W ;

[0164] Y(NO3)3 and LaPO4 coating Al2O 3W The mass ratio of water to deionized water is 21:7:350;

[0165] During the calcination process, the heating rate is 10℃ / min.

[0166] Step (2) Al2O 3W Preparation of the preform: Weigh Al2O3 coated with Y2O3 interface 3W The powder was ball-milled for 2.5 hours at a speed of 200 r / min with PMMA in a mass ratio of 20:3.5.

[0167] The ball-milled powder was dry-pressed at a pressure of 120 MPa for 5 minutes. After demolding, it was subjected to heat treatment in air at 1500℃ for 2 hours to obtain Al2O3 coated with a Y2O3-LaPO4 bilayer interface. 3W Precast concrete;

[0168] During ball milling, Al2O3 coated with a Y2O3-LaPO4 double-layer interface 3W The mass ratio of the grinding beads to the ball bearings is 1:12;

[0169] Step (3) Al-Y alloy infiltration: Al2O 3W The preform was embedded in Al-Y alloy powder and melt-infiltrated under vacuum. The melting infiltration heating rate was 10℃ / min, the melting infiltration temperature was 1500℃, and the melting infiltration time was 2h. This achieved Al-Y alloy in Al2O3 containing a Y2O3-LaPO4 bilayer interface. 3W Sufficient penetration into the precast structure;

[0170] Step (4) Al-Y alloy oxidation: The preform filled with Al-Y alloy obtained in step (2) was oxidized in an air atmosphere. First, the temperature was increased to 900℃ at a heating rate of 10℃ / min and held for 2.5h. Then, the temperature was increased to 1400℃ at a heating rate of 5℃ / min and held for 3.5h to generate a YAG-Al2O3 matrix, thereby obtaining Al2O3. 3W / YAG-Al2O3 composite material.

[0171] This comparative example, without the LaPO4 interface coating, ultimately yielded a material with a flexural strength of 86.76 MPa. The absence of a LaPO4 interface internally caused damage to the whiskers by the Y2O3 coating and alloy, resulting in no obvious whisker structure. However, the surface coating with a Y2O3 interface allowed the Al-Y alloy to penetrate.

[0172] Comparative Example 4

[0173] Step (1) Coating of the LaPO4 interface: Deionized water (H2O) and Al2O 3W The two mixtures were then magnetically stirred for 1 hour to obtain a suspension.

[0174] A 0.8 mol / L La(NO3)3 solution was prepared and uniformly injected into the whisker suspension at a rate of 4 mL / s using a syringe pump. Magnetic stirring was performed during the injection process. After injection, magnetic stirring was performed for 1 h. Then, a 0.8 mol / L Na3PO4 solution was uniformly injected at a rate of 2 mL / s using a syringe pump. Magnetic stirring was performed during the injection process. After injection, magnetic stirring was performed for 2 h to obtain an emulsion.

[0175] The obtained emulsion was filtered to obtain a block with a water content ≤10%. The block with a water content ≤10% was dried at 80-100℃ for 8-12 hours, and finally calcined at 950℃ for 2 hours and pulverized to obtain Al2O coated with LaPO4 interface. 3W ;

[0176] In emulsions, Al2O 3W The mass ratio of La(NO3)3, Na3PO4 and H2O is 55:28:11:2800;

[0177] During the calcination process, the heating rate is 10℃ / min;

[0178] Step (2) Coating of the Y2O3 interface: Y(NO3)3 and Al2O3 coating the LaPO4 interface are coated. 3WThe mixture was prepared by mixing with H2O to obtain a suspension. The suspension was ultrasonically vibrated in a water bath at 20°C for 15 minutes, followed by magnetic stirring for 2.5 hours. The suspension was then dried at 140°C to obtain a block. The block was pulverized, and the pulverized powder was calcined at 950°C for 2 hours to obtain Al2O3 coated with a Y2O3-LaPO4 double-layer interface. 3W ;

[0179] Y(NO3)3 and LaPO4 coating Al2O 3W The mass ratio of water to deionized water is 21:7:350;

[0180] During the calcination process, the heating rate is 10℃ / min.

[0181] Step (3) Al2O 3W Preparation of the preform: Weigh Al2O3 coated with the Y2O3-LaPO4 bilayer interface. 3W The powder was ball-milled for 2.5 hours at a speed of 200 r / min with PMMA in a mass ratio of 20:3.5.

[0182] The ball-milled powder was dry-pressed at a pressure of 120 MPa for 5 minutes. After demolding, it was subjected to heat treatment in air at 1500℃ for 2 hours to obtain Al2O3 coated with a Y2O3-LaPO4 bilayer interface. 3W Precast concrete;

[0183] During ball milling, Al2O3 coated with a Y2O3-LaPO4 double-layer interface 3W The mass ratio of the grinding beads to the ball bearings is 1:12;

[0184] Step (4) Al-Y alloy infiltration: Al2O 3W The preform was embedded in Al-Y alloy powder and melt-infiltrated under vacuum. The melting infiltration heating rate was 10℃ / min, the melting infiltration temperature was 1500℃, and the melting infiltration time was 2h. This achieved Al-Y alloy in Al2O3 containing a Y2O3-LaPO4 bilayer interface. 3W Sufficient penetration into the precast structure;

[0185] Step (5) Al-Y alloy oxidation: The preform filled with Al-Y alloy obtained in step (2) was oxidized in an air atmosphere. First, the temperature was increased to 900℃ at a heating rate of 10℃ / min and held for 2.5h. Then, the temperature was increased to 1400℃ at a heating rate of 5℃ / min and held for 3.5h to generate a YAG-Al2O3 matrix, thereby obtaining Al2O3. 3W / YAG-Al2O3 composite material.

[0186] In this comparative example, due to the excessively rapid injection rate of Na3PO4 solution during the preparation of LaPO4, large LaPO4 particles were found in Al2O3. 3W The surface distribution was uneven, which affected the further coating of Y2O3, resulting in poor Al-Y alloy infiltration effect and uneven alloy distribution. The final sample porosity was 35.28%, and the whiskers were damaged, with a bending strength of only 55.34 MPa.

[0187] Comparative Example 5

[0188] Step (1) Coating of the LaPO4 interface: Deionized water (H2O) and Al2O 3W The two mixtures were then magnetically stirred for 1 hour to obtain a suspension.

[0189] A 0.8 mol / L La(NO3)3 solution was prepared and uniformly injected into the whisker suspension at a rate of 0.5 mL / s using a syringe pump. Magnetic stirring was performed during the injection process. After injection, magnetic stirring was performed for 1 hour. Then, a 0.8 mol / L Na3PO4 solution was uniformly injected at a rate of 0.5 mL / s using a syringe pump. Magnetic stirring was performed during the injection process. After injection, magnetic stirring was performed for 2 hours to obtain an emulsion.

[0190] The obtained emulsion was filtered to obtain a block with a water content ≤10%. The block with a water content ≤10% was dried at 80-100℃ for 8-12 hours, and finally calcined at 950℃ for 2 hours and pulverized to obtain Al2O coated with LaPO4 interface. 3W ;

[0191] In emulsions, Al2O 3W The mass ratio of La(NO3)3, Na3PO4 and H2O is 55:28:11:2800;

[0192] During the calcination process, the heating rate is 10℃ / min;

[0193] Step (2) Coating of the Y2O3 interface: Y(NO3)3 and Al2O3 coating the LaPO4 interface are coated. 3W The mixture was prepared by mixing with H2O to obtain a suspension. The suspension was ultrasonically vibrated in a water bath at 20°C for 15 minutes, followed by magnetic stirring for 2.5 hours. The suspension was then dried at 140°C to obtain a block. The block was pulverized, and the pulverized powder was calcined at 950°C for 2 hours to obtain Al2O3 coated with a Y2O3-LaPO4 double-layer interface. 3W ;

[0194] Y(NO3)3 and LaPO4 coating Al2O 3W The mass ratio of water to deionized water is 21:7:350;

[0195] During the calcination process, the heating rate is 10℃ / min.

[0196] Step (3) Al2O 3W Preparation of the preform: Weigh Al2O3 coated with the Y2O3-LaPO4 bilayer interface. 3W The powder was ball-milled for 2.5 hours at a speed of 200 r / min with PMMA in a mass ratio of 20:3.5.

[0197] The ball-milled powder was dry-pressed at a pressure of 120 MPa for 5 minutes. After demolding, it was subjected to heat treatment in air at 1500℃ for 2 hours to obtain Al2O3 coated with a Y2O3-LaPO4 bilayer interface. 3W Precast concrete;

[0198] During ball milling, Al2O3 coated with a Y2O3-LaPO4 double-layer interface 3W The mass ratio of the grinding beads to the ball bearings is 1:12;

[0199] Step (4) Al-Y alloy infiltration: Al2O 3W The preform was placed directly on Al-Y alloy powder and melt-infiltrated under vacuum. The melting infiltration heating rate was 10℃ / min, the melting infiltration temperature was 1500℃, and the melting infiltration time was 2h. This achieved Al-Y alloy melting at the Y2O3-LaPO4 bilayer interface. 3W Sufficient penetration into the precast structure;

[0200] Step (5) Al-Y alloy oxidation: The preform filled with Al-Y alloy obtained in step (2) was oxidized in an air atmosphere. First, the temperature was increased to 900℃ at a heating rate of 10℃ / min and held for 2.5h. Then, the temperature was increased to 1400℃ at a heating rate of 5℃ / min and held for 3.5h to generate a YAG-Al2O3 matrix, thereby obtaining Al2O3. 3W / YAG-Al2O3 composite material.

[0201] In this comparative example, because the preform was placed directly on top during the melting and infiltration process, the upper part of the preform contained parts where the alloy had not infiltrated or had only a low degree of infiltration, resulting in unevenness in the final material and a final bending strength of only 62.61 MPa.

[0202] Comparative Example 6

[0203] Step (1) Coating of the LaPO4 interface: Deionized water (H2O) and Al2O 3W The two mixtures were then magnetically stirred for 1 hour to obtain a suspension.

[0204] A 0.8 mol / L La(NO3)3 solution was prepared and uniformly injected into the whisker suspension at a rate of 0.5 mL / s using a syringe pump. Magnetic stirring was performed during the injection process. After injection, magnetic stirring was performed for 1 hour. Then, a 0.8 mol / L Na3PO4 solution was uniformly injected at a rate of 0.5 mL / s using a syringe pump. Magnetic stirring was performed during the injection process. After injection, magnetic stirring was performed for 2 hours to obtain an emulsion.

[0205] The obtained emulsion was filtered to obtain a block with a water content ≤10%. The block with a water content ≤10% was dried at 80-100℃ for 8-12 hours, and finally calcined at 950℃ for 2 hours and pulverized to obtain Al2O coated with LaPO4 interface. 3W ;

[0206] In emulsions, Al2O 3W The mass ratio of La(NO3)3, Na3PO4 and H2O is 55:28:11:2800;

[0207] During the calcination process, the heating rate is 10℃ / min;

[0208] Step (2) Coating of the Y2O3 interface: Y(NO3)3 and Al2O3 coating the LaPO4 interface are coated. 3W The mixture was prepared by mixing with H2O to obtain a suspension. The suspension was ultrasonically vibrated in a water bath at 20°C for 15 minutes, followed by magnetic stirring for 2.5 hours. The suspension was then dried at 140°C to obtain a block. The block was pulverized, and the pulverized powder was calcined at 950°C for 2 hours to obtain Al2O3 coated with a Y2O3-LaPO4 double-layer interface. 3W ;

[0209] Y(NO3)3 and LaPO4 coating Al2O 3W The mass ratio of water to deionized water is 21:7:350;

[0210] During the calcination process, the heating rate is 10℃ / min.

[0211] Step (3) Al2O 3W Preparation of the preform: Weigh Al2O3 coated with the Y2O3-LaPO4 bilayer interface. 3W The powder was ball-milled for 2.5 hours at a speed of 200 r / min with PMMA in a mass ratio of 20:3.5.

[0212] The ball-milled powder was dry-pressed at a pressure of 120 MPa for 5 minutes. After demolding, it was subjected to heat treatment in air at 1500℃ for 2 hours to obtain Al2O3 coated with a Y2O3-LaPO4 bilayer interface. 3W Precast concrete;

[0213] During ball milling, Al2O3 coated with a Y2O3-LaPO4 double-layer interface 3W The mass ratio of the grinding beads to the ball bearings is 1:12;

[0214] Step (4) Al-Y alloy infiltration: Al2O 3W The preform was embedded in Al-Y alloy powder and melt-infiltrated under vacuum. The melting infiltration heating rate was 10℃ / min, the melting infiltration temperature was 1500℃, and the melting infiltration time was 2h. This achieved Al-Y alloy in Al2O3 containing a Y2O3-LaPO4 bilayer interface. 3W Sufficient penetration into the precast structure;

[0215] Step (5) Al-Y alloy oxidation: The preform filled with Al-Y alloy obtained in step (2) was oxidized in an air atmosphere. First, the temperature was increased to 1100℃ at a heating rate of 10℃ / min and held for 2.5h. Then, the temperature was increased to 1400℃ at a heating rate of 5℃ / min and held for 3.5h to generate a YAG-Al2O3 matrix, thereby obtaining Al2O3. 3W / YAG-Al2O3 composite material.

[0216] In this comparative example, because the oxidation process temperature reached 1100℃, the Al-Y alloy flowed out during the oxidation process, resulting in the alloy being oxidized on the outer layer when the final sample was taken out. Partial sampling was successful, but the composite material had a porosity of 35%–40%, which was too high, leading to poor material properties, as shown in the attached figure. Figure 12 Some samples were difficult to collect, and some samples were damaged.

[0217] Comparative Example 7

[0218] Step (1) Coating of the LaPO4 interface: Deionized water (H2O) and Al2O 3W The two mixtures were then magnetically stirred for 1 hour to obtain a suspension.

[0219] A 0.8 mol / L La(NO3)3 solution was prepared and uniformly injected into the whisker suspension at a rate of 0.5 mL / s using a syringe pump. Magnetic stirring was performed during the injection process. After injection, magnetic stirring was performed for 1 hour. Then, a 0.8 mol / L Na3PO4 solution was uniformly injected at a rate of 0.5 mL / s using a syringe pump. Magnetic stirring was performed during the injection process. After injection, magnetic stirring was performed for 2 hours to obtain an emulsion.

[0220] The obtained emulsion was filtered to obtain a block with a water content ≤10%. The block with a water content ≤10% was dried at 80-100℃ for 8-12 hours, and finally calcined at 950℃ for 2 hours and pulverized to obtain Al2O coated with LaPO4 interface. 3W ;

[0221] In emulsions, Al2O 3W The mass ratio of La(NO3)3, Na3PO4 and H2O is 55:28:11:2800;

[0222] During the calcination process, the heating rate is 10℃ / min;

[0223] Step (2) Coating of the Y2O3 interface: Y(NO3)3 and Al2O3 coating the LaPO4 interface are coated. 3W The mixture was prepared by mixing with H2O to obtain a suspension. The suspension was ultrasonically vibrated in a water bath at 20°C for 15 minutes, followed by magnetic stirring for 2.5 hours. The suspension was then dried at 140°C to obtain a block. The block was pulverized, and the pulverized powder was calcined at 950°C for 2 hours to obtain Al2O3 coated with a Y2O3-LaPO4 double-layer interface. 3W ;

[0224] Y(NO3)3 and LaPO4 coating Al2O 3W The mass ratio of water to deionized water is 21:7:350;

[0225] During the calcination process, the heating rate is 10℃ / min.

[0226] Step (3) Al2O 3W Preparation of the preform: Weigh Al2O3 coated with the Y2O3-LaPO4 bilayer interface. 3W The powder was ball-milled for 2.5 hours at a speed of 200 r / min with PMMA in a mass ratio of 20:3.5.

[0227] The ball-milled powder was dry-pressed at a pressure of 120 MPa for 5 minutes. After demolding, it was subjected to heat treatment in air at 1500℃ for 2 hours to obtain Al2O3 coated with a Y2O3-LaPO4 bilayer interface. 3W Precast concrete;

[0228] During ball milling, Al2O3 coated with a Y2O3-LaPO4 double-layer interface 3W The mass ratio of the grinding beads to the ball bearings is 1:12;

[0229] Step (4) Al-Y alloy infiltration: Al2O 3WThe preform was embedded in Al-Y alloy powder and melt-infiltrated under vacuum. The melting infiltration heating rate was 10℃ / min, the melting infiltration temperature was 1500℃, and the melting infiltration time was 2h. This achieved Al-Y alloy in Al2O3 containing a Y2O3-LaPO4 bilayer interface. 3W Sufficient penetration into the precast structure;

[0230] Step (5) Al-Y alloy oxidation: The preform filled with Al-Y alloy obtained in step (2) was oxidized in an air atmosphere. First, the temperature was increased to 900℃ at a heating rate of 10℃ / min and held for 2.5h. Then, the temperature was increased to 1500℃ at a heating rate of 5℃ / min and held for 3.5h to generate a YAG-Al2O3 matrix, thereby obtaining Al2O3. 3W / YAG-Al2O3 composite material.

[0231] In this comparative example, the reaction temperature of the Al-Y alloy was increased to 1500℃, ultimately producing Al2O3 with a flexural strength of 172.28 MPa. 3W The porosity of the YAG-Al2O3 composite material is around 9%. Compared with the final sample oxidized at 1420℃, the porosity is not much different, but the strength decreases significantly. This is because the reaction at 1500℃ causes greater internal stress in the matrix during the formation process, which partially destroys the internal whisker skeleton structure, thus reducing its strength.

[0232] To illustrate the properties of the composite material prepared by the method provided in this invention, the accompanying drawings are provided.

[0233] Figure 9 This is a simulation of stress (a) and strain (b) material state during the melting and infiltration process in Example 3. Figure 9 (a) is a stress distribution diagram. Figure 9 (b) is the strain distribution diagram, from Figure 9 As can be seen, the overall stress and strain are in a low state.

[0234] Figure 10 Comparative analysis of the melt infiltration of three groups of preforms: Examples 1, 2, and Example 3; among them, Figure 10 (a) Figure 10 (b) Figure 10 (c) shows SEM images of the interface-free whisker preform, the LaPO4 interface preform, and the Y2O3-LaPO4 bilayer interface preform after alloy infiltration. It can be observed that only the bilayer interface preform achieved alloy infiltration.

[0235] Figure 11 The image shown is a mercury intrusion porosimetry diagram of a secondary porous structure in Example 3. This structure is beneficial for controlling volume changes during the subsequent alloy oxidation expansion process.

[0236] Figure 12 The image shows a sample of alloy 6 after infiltration. This sample has achieved alloy infiltration, with a porosity of about 15%.

[0237] Figure 13 The creep curve of Example 3 shows three stages, with the creep rate increasing from 1.119 × 10⁻⁶. -6 / s decreased to 4.448×10 -7 The / s indicates that densification will still occur during high-temperature load-bearing, further improving its creep resistance.

[0238] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a multiphase ceramic matrix composite material with a double-layer interface, characterized in that, Includes the following steps: By sequentially coating the surface of Al2O3 whiskers with an interfacial layer of LaPO4 and Y2O3, Al2O3 is obtained. 3W Precast concrete; Al2O 3W The preform is embedded in Al-Y alloy powder, and after melting and infiltration, it is oxidized in an air atmosphere to obtain a multiphase ceramic matrix composite material with a double-layer interface. Al2O 3W The volume fraction is 35%~40%; The melting and infiltration process includes: melting and infiltration in a vacuum environment, with a melting and infiltration heating rate of 10~15℃ / min, a melting and infiltration temperature of 1450~1520℃, and a melting and infiltration time of 2~3h; The oxidation treatment in air includes: heating the melt-infiltrated product to 900-950 °C at a heating rate of 5-10 °C / min in air, holding it at that temperature for 2-3 hours, and then heating it to 1400-1450 °C at a heating rate of 5-8 °C / min, holding it at that temperature for 3-4 hours.

2. The method for preparing the multiphase ceramic matrix composite material with a double-layer interface according to claim 1, characterized in that, The surface of Al2O3 whiskers is sequentially coated with a LaPO4 interface layer with a thickness of 10~200nm, and the surface of the Y2O3 interface layer has a thickness of 20~250nm.

3. The method for preparing the multiphase ceramic matrix composite material with a double-layer interface according to claim 1, characterized in that, An interface layer of LaPO4 is sequentially coated onto the surface of Al2O3 whiskers, including: Al2O3 whiskers were dispersed in an aqueous solvent to obtain a suspension; Add La(NO3)3 solution and Na3PO4 solution to the suspension, mix well, and obtain an emulsion; After filtering and drying, the emulsion was calcined at 950~1200 ℃ for 1.5~3h to obtain Al2O3 whiskers coated with LaPO4 interface layer.

4. The method for preparing the multiphase ceramic matrix composite material with a double-layer interface according to claim 3, characterized in that, In the emulsion, the mass ratio of Al2O3 whiskers, La(NO3)3, Na3PO4 and water solvent is (48~64):28:11:(2400~3200).

5. The method for preparing the multiphase ceramic matrix composite material with a double-layer interface according to claim 1, characterized in that, The Al2O 3W During the preparation of the preform, LaPO4 is coated onto the surface of Al2O3 whiskers to obtain Al2O3 whiskers with a LaPO4 interface layer, followed by a process of coating with a Y2O3 interface layer, including: Y(NO3)3 and Al2O3 whiskers coated with LaPO4 interface layer were uniformly dispersed in an aqueous solvent to obtain a suspension; After drying the suspension, it was calcined at 850-1200℃ for 1.5-3 hours to obtain Al2O. 3W Precast concrete; The mass ratio of Y(NO3)3, Al2O3 whiskers coating the LaPO4 interface layer, and water solvent must be 21:(6~8):(300~400).

6. The method for preparing the multiphase ceramic matrix composite material with a double-layer interface according to claim 1, characterized in that, The Al2O 3W During the preform preparation process, after sequentially coating the Al2O3 whisker surface with an interface layer of LaPO4 and Y2O3, the process also includes: The product, in which LaPO4 and Y2O3 interface layers are sequentially coated on the surface of Al2O3 whiskers, is mixed with PMMA and then ground. The ground powder was dry-pressed and then heat-treated in air at 1350-1550 °C for 2-3 h to obtain Al2O. 3W Precast concrete.

7. A multiphase ceramic matrix composite material with a double-layer interface prepared by the method according to any one of claims 1 to 6.

8. The application of the multiphase ceramic matrix composite material with a double-layer interface as described in claim 7 in the hot-end structural components of an aero-engine.

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