Alumina-based composite ceramic material and method for producing the same

Abstract

The application provides an alumina-based composite ceramic material and a preparation method thereof, and the preparation method simultaneously performs ultrasonic dispersion operation and mechanical mixing operation in the first mixing and the second mixing in the pretreatment step and the mixing step. The continuous action of the mechanical force can destroy the agglomerates, and the cavitation effect of the ultrasonic waves can further destroy the spontaneous agglomeration tendency of the mixed materials due to the high surface activity of the reinforcing agent, instantaneously eliminate the re-formed agglomeration tendency, effectively prevent the occurrence of secondary agglomeration, uniformly disperse the functional raw materials in the raw materials, better integrate the functional raw materials into the matrix material, and form a more fine and uniform microstructure. The two types of sintering aids are used in combination, and the processing operation in the above preparation method can effectively improve the interface bonding strength between the alumina and the hard phase particles, make the mechanical properties of the alumina-based composite ceramic material more uniform, and make the comprehensive mechanical properties more excellent.

Description

Technical Field

[0001] This invention relates to the field of ceramic materials technology, and more specifically, to an alumina-based composite ceramic material and its preparation method. Background Technology

[0002] Alumina ceramics, as an important advanced inorganic non-metallic material, possess unique physicochemical properties—high melting point, high hardness, excellent wear resistance, and high-temperature stability—demonstrating irreplaceable value in multiple key fields. From high-tech applications in aerospace to high-temperature resistant components in the automotive industry, alumina ceramics are ubiquitous. However, their inherent brittleness and low toughness limit their application range and reliability under high load conditions. Ceramic materials are prone to brittle fracture upon external impact, severely shortening their service life. To overcome this challenge, researchers have explored various toughening strategies, including particle dispersion toughening, whisker toughening, and their synergistic effects. While these have achieved some success in improving the toughness of alumina ceramics, they often fail to simultaneously address the hardness and flexural strength of the ceramic material, resulting in alumina-based ceramics with poor overall mechanical properties.

[0003] Furthermore, among numerous toughening methods, sintering alumina with various reinforcing phases has become a classic approach for preparing high-performance alumina-based composite ceramic materials. The core of this method lies in ensuring that the reinforcing phase is uniformly dispersed within the alumina matrix to form a stable microstructure, thereby maximizing the reinforcing effect. Traditionally, the direct mixing method is widely adopted due to its simplicity; it only requires mixing alumina powder and reinforcing phase powder in anhydrous ethanol via ball milling, followed by prolonged drying to obtain a composite powder, which is then sintered at high temperature to form the composite ceramic material. Existing technologies have successfully prepared alumina-based composite ceramic materials by directly mixing alumina and silicon nitride powders, ball milling, and vacuum drying.

[0004] While direct mixing methods offer advantages in terms of process convenience, they also present significant drawbacks in practical applications. For instance, the non-uniform dispersion of the reinforcing phase within the alumina matrix, particularly the spontaneous agglomeration tendency of smaller-sized reinforcing particles due to their inherent high surface activity, greatly weakens the consistency of the composite material's mechanical properties. This inhomogeneous microstructure leads to significant performance differences in different regions of the material. These differences can cause premature local failure when subjected to high stress in areas with weaker mechanical properties, ultimately affecting the overall service stability and lifespan of the alumina-based composite ceramic material. Therefore, developing an effective mixing technique to improve the uniformity of the reinforcing phase distribution within the matrix is ​​of paramount importance for enhancing the overall performance of alumina-based composite ceramic materials.

[0005] Based on the above analysis, how to effectively improve the soft and hard agglomeration phenomena between enhanced phase powders during the preparation of alumina-based composite ceramic materials, and improve the performance consistency and comprehensive mechanical properties of alumina-based composite ceramic materials, has become the key to further improving the performance of alumina-based composite ceramic materials. Summary of the Invention

[0006] The main objective of this invention is to provide an alumina-based composite ceramic material and its preparation method, in order to solve the problems of soft and hard agglomeration among raw materials in the preparation process of alumina-based composite ceramic materials in the prior art, and to effectively improve the comprehensive performance of alumina-based composite ceramic materials.

[0007] This invention provides a method for preparing an alumina-based composite ceramic material, comprising the following steps: Pretreatment: mixing raw materials including alumina powder, a reinforcing agent, a sintering aid, and a solvent; the resulting slurry is then subjected to a first mixing process to obtain a first slurry; wherein the first mixing process includes simultaneous first ultrasonic dispersion and first mechanical mixing; Mixing step: ball milling the first slurry to obtain a second slurry; subjecting the second slurry to a second mixing process to obtain a third slurry; drying and sieving the third slurry to obtain a mixed powder; wherein the second mixing process includes simultaneous second ultrasonic dispersion and second mechanical mixing; Sintering step: hot-pressing and sintering the mixed powder, followed by cooling, to obtain the alumina-based composite ceramic material; wherein the sintering aid comprises a first component and a second component, the first component being one or more of Mo, Ni, and Co; and the second component being MgO and / or Y2O3.

[0008] Further, the time for the first mixing and the second mixing are each independently selected from 20 to 100 min; preferably, the time for the first mixing and the second mixing are each independently selected from 20 to 60 min; preferably, the ultrasonic frequency during the first ultrasonic dispersion and the second ultrasonic dispersion processes are each independently selected from 20 to 40 kHz; more preferably, the ultrasonic frequency during the first ultrasonic dispersion and the second ultrasonic dispersion processes are each independently selected from 35 to 40 kHz; preferably, the mixing speed during the first mechanical mixing and the second mechanical mixing processes are each independently selected from 100 to 600 rpm; more preferably, the mixing speed during the first mechanical mixing and the second mechanical mixing processes are each independently selected from 150 to 350 rpm.

[0009] Further, in the sintering aid, the weight ratio of the first component and the second component is (0.1 to 10):1; preferably, in the sintering aid, the weight ratio of the first component and the second component is (0.2 to 5):1.

[0010] Furthermore, by weight, the raw materials include: 45 to 80 parts of alumina powder, 15 to 50 parts of reinforcing agent, and 0.5 to 6.5 parts of sintering aid.

[0011] Furthermore, the ball milling speed is 250–500 rpm, and the time is 12–48 h.

[0012] Further, the reinforcing agent is one or more of TiC, TiN, and Ti(C,N); preferably, the particle size of the reinforcing agent is 0.02≤D50≤1μm.

[0013] Furthermore, the hot pressing sintering temperature is 1600–1700℃, the hot pressing sintering time is 20–120 min, and the hot pressing sintering pressure is 25–35 MPa; preferably, the vacuum degree of the hot pressing sintering process is 5–100 Pa.

[0014] Furthermore, the drying is rotary evaporation drying; preferably, the vacuum degree of the drying process is 150-200 mbar; preferably, the drying temperature is 50-70°C and the time is 0.5-1.5 h.

[0015] Further, the particle size of the mixed powder is 100-220 mesh; preferably, the solid content of the first slurry is 5-20%; preferably, the solvent is methanol and / or ethanol.

[0016] According to another aspect of the present invention, an alumina-based composite ceramic material is also provided, which is prepared by the above-described method for preparing alumina-based composite ceramic materials.

[0017] This invention provides a method for preparing alumina-based composite ceramic materials. In the pretreatment and mixing steps, both ultrasonic dispersion and mechanical mixing are performed simultaneously during the first and second mixing processes. During these operations, the continuous mechanical force breaks down agglomerates, while the cavitation effect of ultrasound further disrupts the spontaneous agglomeration tendency caused by the inherent high surface activity of the reinforcing agent, instantly eliminating the reformation tendency of agglomeration. This continuous power input keeps the powder in a dynamic state throughout the mixing process, effectively preventing secondary agglomeration and ensuring uniform dispersion of functional raw materials such as reinforcing agents and sintering aids. This allows for better integration into the matrix material, forming a finer and more uniform microstructure. Furthermore, this application combines two sintering aids in a compound, along with the mixing method described above, which not only promotes the sintering and densification of the alumina matrix but also further improves the interfacial bonding strength between alumina and hard phase particles, thereby enhancing the overall mechanical properties of the material. The synergistic effect of these multiple mechanisms further ensures the uniform distribution of the reinforcing phase throughout the matrix, resulting in more uniform mechanical properties in the prepared alumina-based composite ceramic material. Furthermore, this preparation method offers advantages such as high efficiency, simple operation, and strong controllability, particularly for the large-scale preparation of alumina-based composite ceramic materials. Attached Figure Description

[0018] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0019] Figure 1 The SEM image of the mixed powder prepared in Example 17 of the present invention is shown;

[0020] Figure 2 The energy spectrum of Al element in the mixed powder prepared in Example 17 of the present invention is shown;

[0021] Figure 3 The energy spectrum of Ti element in the mixed powder prepared in Example 17 of the present invention is shown;

[0022] Figure 4 SEM images of the mixed powder prepared in Comparative Example 1 of the present invention are shown.

[0023] Figure 5 The energy spectrum of Al element in the mixed powder prepared in Comparative Example 1 of the present invention is shown.

[0024] Figure 6 The energy spectrum of Ti element in the mixed powder prepared in Comparative Example 1 of the present invention is shown. Detailed Implementation

[0025] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0026] As described in the background section, sintering alumina powder with various types of reinforcing phase materials is a classic method for preparing high-performance alumina-based composite ceramic materials. However, the non-uniform dispersion of reinforcing agents and other components in the alumina matrix significantly weakens the uniformity of the mechanical properties of the composite ceramic material. This defect means that once the composite ceramic material is subjected to high stress in mechanically weaker areas, it may experience localized performance failure, ultimately affecting the service stability and lifespan of the entire alumina-based composite ceramic material. Therefore, effectively improving the soft and hard agglomeration phenomena among powder particles during the preparation of alumina-based composite ceramic materials, and enhancing the performance consistency and overall mechanical properties of alumina-based composite ceramic materials, has become crucial for further improving the performance of alumina-based composite ceramic materials.

[0027] To address the aforementioned problems, this invention provides a method for preparing an alumina-based composite ceramic material. The method includes the following steps: Pretreatment: mixing raw materials including alumina powder, a reinforcing agent, a sintering aid, and a solvent; the resulting slurry is then subjected to a first mixing process to obtain a first slurry; wherein the first mixing process includes simultaneous first ultrasonic dispersion and first mechanical mixing; Mixing step: ball milling the first slurry to obtain a second slurry; subjecting the second slurry to a second mixing process to obtain a third slurry; drying and sieving the third slurry to obtain a mixed powder; wherein the second mixing process includes simultaneous second ultrasonic dispersion and second mechanical mixing; Sintering step: hot-pressing and sintering the mixed powder, followed by cooling, to obtain the alumina-based composite ceramic material; wherein the sintering aid includes a first component and a second component, the first component being one or more of Mo, Ni, and Co; and the second component being MgO and / or Y2O3.

[0028] Specifically, in the above-mentioned method for preparing alumina-based composite ceramic materials, the raw materials for preparing alumina-based composite ceramic materials are first pretreated, including: mixing alumina powder, reinforcing agent, sintering aid, and solvent; then simultaneously subjecting the resulting slurry to ultrasonic dispersion and mechanical mixing. This mixing method ensures that the alumina powder, reinforcing agent, and sintering aid are fully dispersed in the solvent, resulting in a uniformly mixed first slurry. Next, the first slurry is ball-milled to further reduce the particle size of the raw materials used to prepare the alumina-based composite ceramic material and improve the uniformity of the alumina powder, reinforcing agent, and sintering aid. The ball-milled first slurry is then subjected to simultaneous ultrasonic dispersion and mechanical mixing to further improve the mixing of the ball-milled second slurry, resulting in a third slurry. The fully mixed third slurry is then dried and sieved to obtain a mixed powder used to prepare the alumina-based composite ceramic material. Finally, the obtained mixed powder is hot-pressed and sintered, then cooled to obtain the alumina-based composite ceramic material.

[0029] In particular, the inventors creatively discovered through extensive experimentation that simultaneously performing ultrasonic dispersion and mechanical mixing during the pretreatment and the first and second mixing processes of the mixing step, along with the combined use of two types of sintering aids, can result in alumina-based composite ceramic materials with better overall performance and more uniform mechanical properties. The reasons for this may include the following aspects:

[0030] Firstly, ultrasonic technology utilizes the cavitation effect generated by high-frequency vibration to rapidly break up agglomerates between powder particles, promoting particle refinement and homogenization, and increasing the specific surface area and contact degree between raw materials. When ultrasonic dispersion and mechanical stirring are carried out simultaneously, the continuous mechanical force can destroy agglomerates, while the cavitation effect of ultrasound can further destroy the spontaneous agglomeration tendency in the mixed material caused by the inherent high surface activity of the reinforcing agent, instantly eliminating the tendency to reform agglomeration. Under the influence of this dual mechanism, the uniformity and dispersion efficiency of the various components in the raw materials for preparing alumina-based composite ceramic materials are greatly improved.

[0031] Secondly, compared to using ultrasonic dispersion or mechanical mixing alone, which can lead to the re-agglomeration of deagglomerated powders and insufficient deagglomeration during mixing, thus affecting the dispersibility of the raw materials for preparing alumina-based composite ceramic materials, simultaneous ultrasonic dispersion and mechanical mixing maintain a dynamic treatment of the powder throughout the mixing process. This effectively prevents secondary agglomeration and further ensures the uniform distribution of the reinforcing phase throughout the matrix.

[0032] Third, uniformly dispersing reinforcing agents and other components in the raw materials allows them to better integrate into the matrix material, forming a finer and more uniform microstructure. This results in more consistent performance across different regions, thereby affecting the mechanical properties of alumina-based composite ceramic materials, such as flexural strength and toughness, and enhancing their service life. Furthermore, simultaneous ultrasonic and mechanical mixing can shorten the overall processing time and improve the preparation efficiency of alumina-based composite ceramic materials.

[0033] Fourth, the sintering aid includes a first component and a second component. The first component is one or more of Mo, Ni, and Co; the second component is MgO and / or Y2O3. Adding sintering aids during the preparation of alumina-based composite ceramic materials helps lower the sintering temperature and promotes the bonding between components, which is beneficial for forming a dense microstructure and further improving the overall performance of the alumina-based composite ceramic materials. This application uses a combination of sintering aids including the first and second components, which is beneficial for further improving the performance of alumina-based composite ceramic materials. This is because the first component of the aforementioned sintering aid is a metallic elemental sintering aid, which easily melts into a liquid phase during sintering. The liquid phase sintering aid has good wettability to hard phase particles, allowing it to penetrate into the micropores and cracks of the particles, and even grain boundaries, filling the gaps in the ceramic particle material. This is beneficial for further improving the density of the alumina-based composite ceramic material and strengthening the interfacial bonding strength. The second component of the aforementioned sintering aid is a metal oxide-type sintering aid. This type of sintering aid not only inhibits alumina grain growth, resulting in a uniform and fine microstructure, but also reacts with alumina during sintering to form a second phase at the grain boundaries, creating a "pinning" effect that further improves the material's mechanical properties. Through extensive experimentation, the inventors creatively discovered that combining the two sintering aids (including the first and second components) with the aforementioned mixing method not only promotes the densification of the alumina matrix during sintering but also enhances the interfacial bonding strength between alumina and hard phase particles, thereby further improving the material's mechanical properties.

[0034] In summary, the preparation method for alumina-based composite ceramic materials provided in this application, through simultaneous ultrasonic dispersion and mechanical mixing, ensures thorough and uniform mixing of components such as alumina powder, reinforcing agents, and sintering aids in the raw materials. This results in improved overall mechanical properties and toughness of the prepared alumina-based composite ceramic material. In particular, the combined use of sintering aids, including the first and second components, along with the aforementioned pretreatment and mixing methods, further enhances the performance of the prepared alumina-based composite ceramic material. Furthermore, this preparation method offers advantages such as high efficiency, simple operation, and strong controllability, particularly for the large-scale preparation of alumina-based composite ceramic materials.

[0035] In a preferred embodiment, the times for the first and second mixing are each independently selected from 20 to 100 minutes. Controlling the times for the first and second mixing within this range allows for more uniform dispersion of raw materials such as alumina powder, reinforcing agents, and sintering aids. Preferably, the times for the first and second mixing are each independently selected from 20 to 60 minutes; this range allows for more uniform dispersion of raw materials while further improving preparation efficiency. Preferably, during the first and second ultrasonic dispersion processes, the ultrasonic frequencies are each independently selected from 20 to 40 kHz; preferably, during the first and second mechanical mixing processes, the mixing speeds are each independently selected from 100 to 600 rpm. Too low an ultrasonic frequency is detrimental to powder dispersion, while too high an ultrasonic frequency fails to further improve dispersion and also causes unnecessary energy waste. Controlling the parameters of the ultrasonic dispersion and mechanical mixing operations during the first and second mixing processes within the above ranges allows for more uniform mixing of the raw materials used to prepare alumina-based composite ceramic materials. More preferably, in the first and second ultrasonic dispersion processes, the ultrasonic frequency is independently selected from 35 to 40 kHz; more preferably, in the first and second mechanical mixing processes, the mixing speed is independently selected from 150 to 350 rpm. Controlling the parameters of the ultrasonic dispersion and mechanical mixing operations in the first and second mixing processes within the above-mentioned preferred ranges yields even better results.

[0036] In a preferred embodiment, the weight ratio of the first component to the second component in the sintering aid is (0.1–10):1. Controlling the ratio within this range helps to better leverage their synergistic effect, further improving the mechanical properties and toughness of the alumina-based composite ceramic material. More preferably, the weight ratio of the first component to the second component in the sintering aid is (0.2–5):1. Controlling the ratio within this preferred range further enhances the above-mentioned effect, resulting in alumina-based composite ceramic material with even better performance.

[0037] In a preferred embodiment, the raw materials, by weight, include: 45-80 parts of alumina powder, 15-50 parts of reinforcing agent, and 0.5-6.5 parts of sintering aid. During the preparation of alumina-based composite ceramic materials, by controlling the proportions of alumina powder, reinforcing agent, and sintering aid within the above-mentioned range, the overall mechanical properties and toughness of the prepared alumina-based composite ceramic material can be improved. Preferably, the reinforcing agent is one or more of TiC, TiN, and Ti(C,N). These types of reinforcing agents can better exert their effects, which is beneficial for further improving the mechanical properties of the alumina-based composite ceramic material, and thus for extending its service life. In particular, the combined action of the above-mentioned reinforcing agent and the sintering aid provided by this invention can further improve the performance of the alumina-based composite ceramic material. Preferably, the particle size of the reinforcing agent is 0.02≤D50≤1μm. Controlling the particle size of the reinforcing agent within the above-mentioned range can better exert the effect of the reinforcing agent, which is beneficial for further improving the overall performance of the alumina-based composite ceramic material. Preferably, the reinforcing agent is at least two of TiC, TiN, and Ti(C,N), and the performance of the alumina-based composite ceramic material is better under the above conditions.

[0038] In a preferred embodiment, the ball milling speed is 250–500 rpm, and the time is 12–48 h. Controlling the ball milling speed and time within the above parameter range can improve the uniformity of the prepared alumina-based composite ceramic material, which is beneficial to further improving the uniformity and density of the mechanical properties of the prepared alumina-based composite ceramic material.

[0039] In a preferred embodiment, the hot-pressing sintering temperature is 1600–1700°C, the hot-pressing sintering time is 20–120 min, and the hot-pressing sintering pressure is 25–35 MPa; preferably, the vacuum degree of the hot-pressing sintering process is 5–100 Pa. Controlling the sintering process parameters within the above ranges is beneficial for obtaining alumina-based composite ceramic materials with better mechanical properties.

[0040] In a preferred embodiment, the drying is rotary evaporation drying. The third slurry obtained by rotary evaporation drying maintains the powder in a dynamically dispersed state, effectively mitigating the secondary agglomeration phenomenon caused by rapid solvent evaporation during drying. This method improves the drying rate while effectively overcoming the viscosity problems that may arise from conventional drying methods, helping to maintain the uniformity of the slurry composition and avoiding performance inconsistencies due to uneven drying. Preferably, the vacuum degree during the drying process is 150–200 mbar; preferably, the drying temperature is 50–70°C, and the time is 0.5–1.5 h. Performing the rotary evaporation drying operation under vacuum conditions and controlling the drying temperature and time within the above ranges can further improve the consistency of the performance of the alumina-based composite ceramic material.

[0041] In a preferred embodiment, the particle size of the mixed powder is 100-220 mesh; preferably, the solid content of the first slurry is 5-20%; preferably, the solvent is methanol and / or ethanol. Methanol and ethanol, as protic organic solvents, enable the first slurry to be mixed more uniformly.

[0042] According to another aspect of the present invention, an alumina-based composite ceramic material is also provided, which is prepared by the above-described preparation method; the parameters of the preparation process are controlled within a preferred range, the standard deviation of the flexural strength of the alumina-based composite ceramic material is less than 40%, and its average flexural strength is ≥521 MPa.

[0043] It should be noted that, due to the specific nature of the materials field and the limitations of existing testing and characterization methods, a comprehensive characterization of the materials obtained by the above preparation method is not possible. However, experiments have confirmed that this alumina-based composite ceramic material can improve the stability of the mechanical properties of alumina-based composite ceramic materials, indicating that the preparation method of this invention improves the material itself.

[0044] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0045] Example 1

[0046] The raw material composition for preparing alumina-based composite ceramic materials is: Al2O3-TiC-TiN-Ni-MgO.

[0047] Pretreatment: 59 parts of alumina powder, 38 parts of reinforcing agent (including 24 parts of TiC powder and 14 parts of TiN powder), and 3 parts of sintering aid (including 2 parts of Ni powder and 1 part of MgO powder) were mixed with anhydrous ethanol. The resulting mixture was then placed in an ultrasonic stirrer for simultaneous ultrasonic dispersion and mechanical mixing to obtain a first slurry with a solid content of 20%. The ultrasonic frequency was 40 kHz, the mechanical mixing speed was 250 rpm, and the mixing time was 30 min.

[0048] Mixing steps: The first slurry was placed in a ball mill and milled at 400 rpm for 24 hours to obtain the second slurry. The second slurry was then placed in an ultrasonic stirrer for simultaneous ultrasonic dispersion and mechanical mixing to obtain the third slurry. The third slurry was dried in a rotary evaporator at 60°C and 170 mbar for 1 hour, and then sieved to obtain a mixed powder smaller than 100 mesh. The ultrasonic frequency was 40 kHz, the mechanical mixing speed was 300 rpm, and the mixing time was 30 minutes.

[0049] Sintering step: The above-obtained mixed powder is loaded into a graphite mold and hot-pressed under a vacuum of 100 Pa. The product is then cooled to room temperature in the furnace to obtain an alumina-based composite ceramic material. The hot-pressing sintering temperature is 1650℃, the hot-pressing sintering time is 20 min, and the hot-pressing sintering pressure is 30 MPa.

[0050] Example 2

[0051] The raw material composition for preparing alumina-based composite ceramic materials is: Al2O3-TiC-TiN-Ni-MgO.

[0052] Pretreatment: 59 parts of alumina powder, 38 parts of reinforcing agent (including 24 parts of TiC powder and 14 parts of TiN powder), and 3 parts of sintering aid (including 2 parts of Ni powder and 1 part of MgO powder) were mixed with anhydrous ethanol. The resulting mixture was then placed in an ultrasonic stirrer for simultaneous ultrasonic dispersion and mechanical mixing to obtain a first slurry with a solid content of 20%. The ultrasonic frequency was 35 kHz, the mechanical mixing speed was 350 rpm, and the mixing time was 20 min.

[0053] Mixing steps: The first slurry was placed in a ball mill and milled at 400 rpm for 24 hours to obtain the second slurry. The second slurry was then placed in an ultrasonic stirrer for simultaneous ultrasonic dispersion and mechanical mixing to obtain the third slurry. The third slurry was dried in a rotary evaporator at 60°C and 170 mbar for 1 hour, and then sieved to obtain a mixed powder smaller than 100 mesh. The ultrasonic frequency was 35 kHz, the mechanical mixing speed was 350 rpm, and the mixing time was 20 minutes.

[0054] Sintering step: The above-obtained mixed powder is loaded into a graphite mold and hot-pressed under a vacuum of 100 Pa. The product is then cooled to room temperature in the furnace to obtain an alumina-based composite ceramic material. The hot-pressing sintering temperature is 1650℃, the hot-pressing sintering time is 20 min, and the hot-pressing sintering pressure is 30 MPa.

[0055] Example 3

[0056] The raw material composition for preparing alumina-based composite ceramic materials is: Al2O3-TiC-TiN-Ni-MgO.

[0057] Pretreatment: 59 parts of alumina powder, 38 parts of reinforcing agent (including 24 parts of TiC powder and 14 parts of TiN powder), and 3 parts of sintering aid (including 2 parts of Ni powder and 1 part of MgO powder) were mixed with anhydrous ethanol. The resulting mixture was then placed in an ultrasonic stirrer for simultaneous ultrasonic dispersion and mechanical mixing to obtain a first slurry with a solid content of 20%. The ultrasonic frequency was 40 kHz, the mechanical mixing speed was 150 rpm, and the mixing time was 60 min.

[0058] Mixing steps: The first slurry was placed in a ball mill and milled at 400 rpm for 24 hours to obtain the second slurry. The second slurry was then placed in an ultrasonic stirrer for simultaneous ultrasonic dispersion and mechanical mixing to obtain the third slurry. The third slurry was dried in a rotary evaporator at 60°C and 170 mbar for 1 hour, and then sieved to obtain a mixed powder smaller than 100 mesh. The ultrasonic frequency was 40 kHz, the mechanical mixing speed was 150 rpm, and the mixing time was 60 minutes.

[0059] Sintering step: The above-obtained mixed powder is loaded into a graphite mold and hot-pressed under a vacuum of 100 Pa. The product is then cooled to room temperature in the furnace to obtain an alumina-based composite ceramic material. The hot-pressing sintering temperature is 1650℃, the hot-pressing sintering time is 20 min, and the hot-pressing sintering pressure is 30 MPa.

[0060] Example 4

[0061] The raw material composition for preparing alumina-based composite ceramic materials is: Al2O3-TiC-TiN-Ni-MgO.

[0062] Pretreatment: 59 parts of alumina powder, 38 parts of reinforcing agent (including 24 parts of TiC powder and 14 parts of TiN powder), and 3 parts of sintering aid (including 2 parts of Ni powder and 1 part of MgO powder) were mixed with anhydrous ethanol. The resulting mixture was then placed in an ultrasonic stirrer for simultaneous ultrasonic dispersion and mechanical mixing to obtain a first slurry with a solid content of 20%. The ultrasonic frequency was 20 kHz, the mechanical mixing speed was 100 rpm, and the mixing time was 100 min.

[0063] Mixing steps: The first slurry was placed in a ball mill and milled at 500 rpm for 12 hours to obtain the second slurry. The second slurry was then placed in an ultrasonic stirrer for simultaneous ultrasonic dispersion and mechanical mixing to obtain the third slurry. The third slurry was dried in a rotary evaporator at 50°C and 150 mbar for 1.5 hours, and then sieved to obtain a mixed powder smaller than 100 mesh. The ultrasonic frequency was 20 kHz, the mechanical mixing speed was 100 rpm, and the mixing time was 100 minutes.

[0064] Sintering step: The above-obtained mixed powder is loaded into a graphite mold and hot-pressed under a vacuum of 150 Pa. The product is then cooled to room temperature in the furnace to obtain an alumina-based composite ceramic material. The hot-pressing sintering temperature is 1600℃, the hot-pressing sintering time is 120 min, and the hot-pressing sintering pressure is 25 MPa.

[0065] Example 5

[0066] The raw material composition for preparing alumina-based composite ceramic materials is: Al2O3-TiC-TiN-Ni-MgO.

[0067] Pretreatment: 59 parts of alumina powder, 38 parts of reinforcing agent (including 24 parts of TiC powder and 14 parts of TiN powder), and 3 parts of sintering aid (including 2 parts of Ni powder and 1 part of MgO powder) were mixed with anhydrous ethanol. The resulting mixture was then placed in an ultrasonic stirrer for simultaneous ultrasonic dispersion and mechanical mixing to obtain a first slurry with a solid content of 5%. The ultrasonic frequency was 30 Hz, the mechanical mixing speed was 600 rpm, and the mixing time was 100 min.

[0068] Mixing steps: The first slurry was placed in a ball mill and milled at 250 rpm for 48 hours to obtain the second slurry. The second slurry was then placed in an ultrasonic stirrer for simultaneous ultrasonic dispersion and mechanical mixing to obtain the third slurry. The third slurry was dried in a rotary evaporator at 70°C and 200 mbar for 0.5 hours, and then sieved to obtain a mixed powder smaller than 100 mesh. The ultrasonic frequency was 30 kHz, the mechanical mixing speed was 600 rpm, and the mixing time was 100 minutes.

[0069] Sintering step: The above-obtained mixed powder is loaded into a graphite mold and hot-pressed under a vacuum of 200 Pa. The product is then cooled to room temperature in the furnace to obtain an alumina-based composite ceramic material. The hot-pressing sintering temperature is 1700℃, the hot-pressing sintering time is 20 min, and the hot-pressing sintering pressure is 35 MPa.

[0070] Example 6

[0071] The difference between Example 6 and Example 1 is that the weight ratio of the first component Ni powder and the second component MgO powder in the sintering aid is 0.1:1.

[0072] Example 7

[0073] The difference between Example 7 and Example 1 is that the weight ratio of the first component Ni powder and the second component MgO powder in the sintering aid is 10:1.

[0074] Example 8

[0075] The difference between Example 8 and Example 1 is that the weight ratio of the first component Ni powder and the second component MgO powder in the sintering aid is 0.2:1.

[0076] Example 9

[0077] The difference between Example 9 and Example 1 is that the weight ratio of the first component Ni powder and the second component MgO powder in the sintering aid is 5:1.

[0078] Example 10

[0079] The difference between Example 10 and Example 1 is that the raw material composition for preparing the alumina-based composite ceramic material is: Al2O3-TiC-TiN-Ni-MgO. Specifically, by weight, it includes: 45 parts alumina powder, 50 parts reinforcing agent (including 30 parts TiC powder and 20 parts TiN powder), and 5 parts sintering aid (including 3 parts Ni powder and 2 parts MgO powder).

[0080] Example 11

[0081] The difference between Example 11 and Example 1 is that the raw material composition for preparing the alumina-based composite ceramic material is: Al2O3-TiC-TiN-Ni-MgO. Specifically, by weight, it includes: 80 parts alumina powder, 15 parts reinforcing agent (including 10 parts TiC powder and 5 parts TiN powder), and 5 parts sintering aid (including 2.5 parts Ni powder and 2.5 parts MgO powder).

[0082] Example 12

[0083] The difference between Example 12 and Example 1 is that the raw material composition for preparing the alumina-based composite ceramic material is: Al2O3-TiC-TiN-Ni-MgO. Specifically, by weight, it includes: 50 parts alumina powder, 43.5 parts reinforcing agent (including 29 parts TiC powder and 14.5 parts TiN powder), and 6.5 parts sintering aid (including 4 parts Ni powder and 2.5 parts MgO powder).

[0084] Example 13

[0085] The difference between Example 13 and Example 1 is that the raw material composition for preparing the alumina-based composite ceramic material is: Al2O3-TiC-TiN-Ni-MgO. Specifically, by weight, it includes: 65 parts alumina powder, 34.5 parts reinforcing agent (including 23 parts TiC powder and 11.5 parts TiN powder), and 0.5 parts sintering aid (including 0.25 parts Ni powder and 0.25 parts MgO powder).

[0086] Example 14

[0087] The difference between Example 14 and Example 1 is that the raw material composition for preparing the alumina-based composite ceramic material is: Al2O3-TiC-Co-MgO. By weight, it specifically includes: 59 parts of alumina powder, 38 parts of reinforcing agent TiC powder, and 3 parts of sintering aid (including 2 parts of Co powder and 1 part of MgO powder).

[0088] Example 15

[0089] The difference between Example 15 and Example 1 is that the raw material composition for preparing the alumina-based composite ceramic material is Al2O3-TiN-Ni-Y2O3. Specifically, by weight, it includes: 59 parts alumina powder, 38 parts reinforcing agent TiN powder, and 3 parts sintering aid (including 2 parts Ni powder and 1 part Y2O3 powder).

[0090] Example 16

[0091] The difference between Example 16 and Example 1 is that the raw material composition for preparing the alumina-based composite ceramic material is: Al2O3-Ti(C,N)-Mo-Y2O3. Specifically, by weight, it includes: 59 parts alumina powder, 38 parts reinforcing agent Ti(C,N) powder, and 3 parts sintering aid (including 2 parts Mo powder and 1 part Y2O3 powder).

[0092] Example 17

[0093] The difference between Example 17 and Example 1 is that the raw material composition for preparing the alumina-based composite ceramic material is: Al2O3-TiC-TiN-Ni-Mo-MgO. Specifically, by weight, it includes: 57.5 parts of alumina powder, 37 parts of reinforcing agent (including 29 parts of TiC powder and 8 parts of TiN powder), and 5.5 parts of sintering aid (including 2.2 parts of Ni powder, 2.5 parts of Mo powder, and 0.8 parts of MgO powder).

[0094] Example 18

[0095] The difference between Example 18 and Example 1 is as follows: In the pretreatment process, the ultrasonic frequency is 10Hz, the mechanical mixing speed is 250rpm, and the mixing time is 10min. In the mixing step, the ultrasonic frequency is 10Hz, the mechanical mixing speed is 250rpm, and the mixing time is 5min.

[0096] Comparative Example 1

[0097] The raw material composition for preparing alumina-based composite ceramic materials is: Al2O3-TiC-TiN-Ni-Mo-MgO.

[0098] 57.5 parts of alumina powder, 37 parts of reinforcing agent (including 29 parts of TiC powder and 8 parts of TiN powder), 5.5 parts of sintering aid (including 2.2 parts of Ni powder, 2.5 parts of Mo powder, and 0.8 parts of MgO powder), and anhydrous ethanol were mixed. The resulting mixture was placed in a ball mill and ball-milled at 400 rpm for 24 hours to obtain a second slurry with a solid content of 20%. The obtained second slurry was dried at 60°C and 170 mbar for 1 hour, and then sieved to obtain a mixed powder smaller than 100 mesh. The obtained mixed powder was loaded into a graphite mold and hot-pressed under a vacuum of 100 Pa. The product was then cooled to room temperature in the furnace to obtain an alumina-based composite ceramic material. The hot-pressing sintering temperature was 1650°C, the hot-pressing sintering time was 20 min, and the hot-pressing sintering pressure was 30 MPa.

[0099] Comparative Example 2

[0100] The raw material composition for preparing alumina-based composite ceramic materials is: Al2O3-TiC-TiN-Ni-Mo-MgO.

[0101] Pretreatment: Take 57.5 parts of alumina powder, 37 parts of reinforcing agent (including 29 parts of TiC powder and 8 parts of TiN powder), 5.5 parts of sintering aid (including 2.2 parts of Ni powder, 2.5 parts of Mo powder and 0.8 parts of MgO powder) and anhydrous ethanol, mix them, and then mechanically mix and stir the resulting mixture at 250 rpm for 30 min, and then ultrasonically disperse it at an ultrasonic frequency of 40 Hz for 30 min to obtain a first slurry with a solid content of 20%.

[0102] Mixing steps: The first slurry was placed in a ball mill and milled at 400 rpm for 24 hours to obtain the second slurry. The obtained second slurry was dried at 60°C and 170 mbar for 1 hour, and then sieved to obtain a mixed powder with a mesh size of less than 100.

[0103] Sintering step: The above-obtained mixed powder is loaded into a graphite mold and hot-pressed under a vacuum of 100 Pa. The product is then cooled to room temperature in the furnace to obtain an alumina-based composite ceramic material. The hot-pressing sintering temperature is 1650℃, the hot-pressing sintering time is 20 min, and the hot-pressing sintering pressure is 30 MPa.

[0104] Comparative Example 3

[0105] The raw material composition for preparing alumina-based composite ceramic materials is: Al2O3-TiC-TiN-Ni-Mo-MgO.

[0106] Pretreatment: Take 57.5 parts of alumina powder, 37 parts of reinforcing agent (including 29 parts of TiC powder and 8 parts of TiN powder), 5.5 parts of sintering aid (including 2.2 parts of Ni powder, 2.5 parts of Mo powder and 0.8 parts of MgO powder) and anhydrous ethanol, mix them, and then ultrasonically disperse the mixture at an ultrasonic frequency of 40 Hz for 30 min, and then mechanically mix and stir at a speed of 250 rpm for 30 min to obtain a first slurry with a solid content of 20%.

[0107] Mixing steps: The first slurry was placed in a ball mill and milled at 400 rpm for 24 hours to obtain the second slurry. The obtained second slurry was dried at 60°C and 170 mbar for 1 hour, and then sieved to obtain a mixed powder with a mesh size of less than 100.

[0108] Sintering step: The above-obtained mixed powder is loaded into a graphite mold and hot-pressed under a vacuum of 100 Pa. The product is then cooled to room temperature in the furnace to obtain an alumina-based composite ceramic material. The hot-pressing sintering temperature is 1650℃, the hot-pressing sintering time is 20 min, and the hot-pressing sintering pressure is 30 MPa.

[0109] Comparative Example 4

[0110] The difference between Comparative Example 4 and Example 1 is that the raw material composition for preparing the alumina-based composite ceramic material is Al2O3-TiC-Co. Specifically, by weight, it includes: 59 parts alumina powder, 38 parts reinforcing agent TiC powder, and 3 parts sintering aid Co powder.

[0111] Comparative Example 5

[0112] The difference between Comparative Example 5 and Example 1 is that the raw material composition for preparing the alumina-based composite ceramic material is Al2O3-TiC-MgO. Specifically, by weight, it includes: 59 parts alumina powder, 38 parts reinforcing agent TiC powder, and 3 parts sintering aid MgO powder.

[0113] The ceramic materials prepared in the above embodiments and comparative examples were processed by cutting and polishing three regions of the same sample with diamond wire, resulting in three samples with dimensions of 20mm × 4mm × 3mm, named Sample 1, Sample 2, and Sample 3. The sample selection locations were consistent in each embodiment or comparative example. First, the flexural strength of the above samples was tested. Based on the test data, the average flexural strength and standard deviation were calculated, and the results are shown in Table 1. The average flexural strength reflects the overall strength level of the ceramic materials prepared in the embodiments, i.e., the average load-bearing capacity of the material under bending force; the standard deviation of the flexural strength reflects the strength dispersion of the ceramic materials prepared in the corresponding embodiments. The smaller the standard deviation, the more uniform the strength of the material. Specifically,

[0114] The flexural strength test method includes: using the three-point bending method to test the flexural strength of the sample, with a span of 10 mm and a loading rate of 0.5 mm / min. For specific test procedures, refer to GB / T 6569-2006.

[0115] The standard deviation of flexural strength is calculated using the following formula: (where σ is the standard deviation, x) i The flexural strength of each sample, where μ is the average flexural strength.

[0116] Table 1

[0117]

[0118]

[0119] To better understand the mechanical properties of the prepared ceramic materials, the toughness and hardness properties of each sample were further tested. The results are shown in Table 2, and the specific test methods are as follows:

[0120] Fracture toughness test: The fracture toughness of the sample was tested using the single-sided notched beam method. The span was 10 mm, the notch size was 1.8 ± 0.32 mm, and the loading rate was 0.05 mm / min. For specific test methods, refer to GB / T 23806-2009.

[0121] Hardness test: Polish the surface of the 20mm×4mm×3mm sample, and use a Vickers hardness tester to make indentation points on the polished surface of the sample. The load is 500gf and the holding time is 15s. For specific test methods, refer to GB / T 16534-2009.

[0122] Table 2

[0123]

[0124]

[0125] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0126] In Examples 1 to 18, during the preparation of alumina-based composite ceramic materials, ultrasonic dispersion and mechanical mixing were performed simultaneously in the first and second mixing processes of the pretreatment and mixing steps, and two types of sintering aids were used in combination. According to the results in Tables 1 and 2, the average flexural strength, standard deviation of flexural strength, fracture toughness, and hardness of the alumina-based composite ceramic materials prepared in the above examples are all at a good level, indicating good mechanical properties. Furthermore, the relatively small standard deviation of the corresponding alumina-based composite ceramic materials indicates a small strength dispersion, relatively uniform flexural strength, and better uniformity of mechanical properties. In particular, in Examples 1 to 17, by controlling the parameters in the preparation process within the preferred range, the mechanical properties and distribution uniformity of the corresponding alumina-based composite ceramic materials were more effectively improved. In Comparative Examples 1 to 3, the processing method provided in this application was not used in the preparation process, and the average flexural strength, standard deviation of flexural strength, fracture toughness, and hardness of the prepared alumina-based composite ceramic materials were relatively poor, with a significant difference in the uniformity of mechanical property distribution compared to the examples in this application. In Comparative Examples 4 and 5, although the processing method provided in this application was used, only one type of sintering aid was used. The standard deviation of the flexural strength of the corresponding alumina-based composite ceramic material was acceptable, but its average flexural strength was poor. The overall performance of the corresponding alumina-based composite ceramic material was also significantly different from that of the embodiments in this application.

[0127] To further investigate the properties of the prepared alumina-based composite ceramic material, the mixed powders prepared in Example 17 and Comparative Example 1 were selected, and their microstructure was tested. Figure 1 , Figure 2 , Figure 3 The SEM images, energy dispersive spectroscopy (EDS) spectra of Al and Ti elements of the mixed powder prepared in Example 17 of this invention are shown respectively. Figures 1 to 3 It is evident that in the pretreatment and mixing steps, both ultrasonic dispersion and mechanical mixing are performed simultaneously during the first and second mixing processes, significantly improving the dispersibility of the reinforcing phase in the alumina-based composite powder within the matrix. Among these improvements, Figure 4 , Figure 5 , Figure 6 SEM images, energy dispersive spectroscopy (EDS) spectra of Al and Ti elements of the mixed powder prepared in Comparative Example 1 of this invention are shown respectively. Figures 4 to 6It can be seen that the dispersion performance of the reinforcing phase in the alumina-based composite powder in Comparative Example 1 is poor. Therefore, the processing method in the preparation method of the alumina-based composite ceramic material provided in this application can effectively improve the dispersion of components in the alumina-based composite ceramic material, thereby effectively improving the overall performance of the alumina-based composite ceramic material.

[0128] In summary, the preparation method of the alumina-based composite ceramic material provided in this application simultaneously performs ultrasonic dispersion and mechanical mixing operations in the pretreatment step and the first and second mixing processes of the mixing step. This effectively improves the mechanical properties and uniformity of the prepared alumina-based composite ceramic material. The combined use of two sintering aids, along with the aforementioned preparation process, promotes better sintering and densification of the alumina matrix, and enhances the interfacial bonding strength between the alumina and hard phase particles. This results in better mechanical properties and uniformity of the prepared alumina-based composite ceramic material, leading to superior overall mechanical properties.

[0129] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing an alumina-based composite ceramic material, characterized in that, The preparation method includes the following steps: Pretreatment: Raw materials including alumina powder, reinforcing agent, sintering aid and solvent are mixed, and the resulting slurry is subjected to a first mixing to obtain a first slurry; wherein, the first mixing includes a first ultrasonic dispersion and a first mechanical mixing performed simultaneously; Mixing steps: The first slurry is ball-milled to obtain a second slurry; the second slurry is then mixed in a second manner to obtain a third slurry; the third slurry is dried and sieved to obtain a mixed powder; wherein, the second mixing includes a second ultrasonic dispersion and a second mechanical mixing performed simultaneously; Sintering step: The mixed powder is hot-pressed and sintered, and then cooled to obtain the alumina-based composite ceramic material; the standard deviation of the flexural strength of the alumina-based composite ceramic material is less than 40%, and the average flexural strength is ≥521MPa; The sintering aid comprises a first component and a second component, wherein the first component is one or more of Mo, Ni and Co; and the second component is MgO and / or Y2O3. The mixing times for the first and second mixing are each independently selected from 20 to 100 minutes; In the first and second ultrasonic dispersion processes, the ultrasonic frequencies are each independently selected from 20 to 40 kHz.

2. The method for preparing the alumina-based composite ceramic material according to claim 1, characterized in that, The mixing times for the first and second mixing are each independently selected from 20 to 60 minutes; And / or, during the first ultrasonic dispersion and the second ultrasonic dispersion processes, the ultrasonic frequency is independently selected from 35 to 40 kHz; And / or, during the first mechanical mixing and the second mechanical mixing processes, the mixing speed is independently selected from 100 to 600 rpm; and / or, during the first mechanical mixing and the second mechanical mixing processes, the mixing speed is independently selected from 150 to 350 rpm.

3. The method for preparing the alumina-based composite ceramic material according to claim 1, characterized in that, In the sintering aid, the weight ratio of the first component to the second component is (0.1~10):1; and / or, in the sintering aid, the weight ratio of the first component to the second component is (0.2~5):

1.

4. The method for preparing the alumina-based composite ceramic material according to any one of claims 1 to 3, characterized in that, The raw materials, by weight, include: 45-80 parts of the alumina powder, 15-50 parts of the reinforcing agent, and 0.5-6.5 parts of the sintering aid.

5. The method for preparing the alumina-based composite ceramic material according to any one of claims 1 to 3, characterized in that, The ball mill operates at a speed of 250-500 rpm for 12-48 hours.

6. The method for preparing the alumina-based composite ceramic material according to any one of claims 1 to 3, characterized in that, The reinforcing agent is one or more of TiC, TiN, and Ti(C,N); And / or, the particle size of the reinforcing agent is 0.02≤D50≤1µm.

7. The method for preparing the alumina-based composite ceramic material according to any one of claims 1 to 3, characterized in that, The hot pressing sintering temperature is 1600~1700℃, the hot pressing sintering time is 20~120min, and the hot pressing sintering pressure is 25~35MPa; And / or, the vacuum degree of the hot pressing sintering process is 5~100 Pa.

8. The method for preparing the alumina-based composite ceramic material according to any one of claims 1 to 3, characterized in that, The drying process is rotary evaporation drying; And / or, the vacuum degree of the drying process is 150~200mbar; And / or, the drying temperature is 50~70℃ and the time is 0.5~1.5h.

9. The method for preparing the alumina-based composite ceramic material according to any one of claims 1 to 3, characterized in that, The particle size of the mixed powder is 100~220 mesh; And / or, the solid content of the first slurry is 5-20%; And / or, the solvent is methanol and / or ethanol.

10. An alumina-based composite ceramic material, characterized in that, The alumina-based composite ceramic material is prepared by the method for preparing alumina-based composite ceramic material according to any one of claims 1 to 9.

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