Alumina-based composite ceramic material and preparation method thereof

Abstract

The invention provides an alumina-based composite ceramic material and a preparation method thereof, and according to the preparation method, in a first mixing process and a second mixing process in a pretreatment step and a material mixing step, ultrasonic dispersion operation and mechanical mixing operation are carried out at the same time. Wherein the continuous action of the mechanical force can destroy the aggregate, and the cavitation effect of the ultrasonic wave can further destroy the spontaneous agglomeration tendency generated by the inherent high surface activity of the reinforcing agent in the mixed material, so that the re-formed agglomeration tendency is immediately eliminated, and the occurrence of secondary agglomeration is effectively prevented; the functional raw materials are uniformly dispersed in the raw materials, so that the functional raw materials can be better fused into the base material, and a finer and more uniform microstructure is formed. The two types of sintering aids are compounded for use, and the treatment operation in the preparation method is combined, so that the interface bonding strength between aluminum oxide and hard phase particles can be effectively improved, the mechanical property of the aluminum oxide-based composite ceramic material is more uniform, and the comprehensive mechanical property is better.

Description

Technical Field

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

[0002] As an important advanced inorganic non-metallic material, alumina ceramic material has demonstrated irreplaceable value in many key fields due to its unique physical and chemical properties - high melting point, high hardness, excellent wear resistance and high temperature stability. From high-tech applications in China's aerospace to high-temperature resistant components in the automotive manufacturing industry, alumina ceramic materials are everywhere. However, its inherent brittleness and low toughness limit its application range and reliability under high load conditions. Ceramic materials are prone to brittle fracture when subjected to external impact, which seriously shortens its service life. In order to overcome this challenge, researchers have explored a variety of toughening strategies, including particle dispersion toughening, whisker toughening and their synergistic effects. Although certain effects have been achieved in improving the toughness of alumina ceramic materials, the hardness and flexural strength of ceramic materials are often not taken into account. The comprehensive mechanical properties of the resulting alumina-based ceramic materials are poor.

[0003] In addition, among the many toughening methods, mixing alumina with various reinforcing phases and sintering them has become a classic way to prepare high-performance alumina-based composite ceramic materials. The core of this method is to ensure that the reinforcing phase can be evenly dispersed in the alumina matrix to form a stable microstructure, thereby maximizing the reinforcing effect of the reinforcing phase. Traditionally, the direct mixing method has been widely adopted. It is simple to operate and only requires mixing alumina powder and reinforcing phase powder in anhydrous ethanol medium by ball milling. After a long period of treatment, the composite powder is dried to obtain a composite ceramic material, which is then sintered at high temperature. The prior art has adopted the steps of directly mixing alumina and silicon nitride powder, ball milling and vacuum drying to successfully produce alumina-based composite ceramic materials.

[0004] Although the direct mixing method shows the advantage of convenience in the preparation process, it faces significant defects in practical applications. For example, the non-uniform dispersion of the reinforcing phase in the alumina matrix, especially the spontaneous agglomeration tendency of the smaller-sized reinforcing particles due to their inherent high surface activity, greatly weakens the consistency of the mechanical properties of the composite material. This uneven microstructure leads to significant differences in the performance of the material in different regions. This difference may cause local premature failure once the mechanically weak parts of the material are subjected to high stress, ultimately affecting the service stability and life of the entire alumina-based composite ceramic material. Therefore, developing an effective mixing technology to improve the uniformity of the distribution of the reinforcing phase in the matrix is ​​of great significance to improving the comprehensive performance of alumina-based composite ceramic materials.

[0005] Based on the above analysis, how to effectively improve the soft agglomeration and hard agglomeration phenomena between equal 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 purpose of the present invention is to provide an alumina-based composite ceramic material and a preparation method thereof, so as to solve the soft agglomeration and hard agglomeration phenomena between raw materials in the preparation process of alumina-based composite ceramic materials in the prior art, aiming to effectively improve the comprehensive performance of alumina-based composite ceramic materials.

[0007] The present invention provides a preparation method of an alumina-based composite ceramic material, which comprises the following steps: pretreatment: mixing raw materials including alumina powder, a reinforcing agent, and a sintering aid with a solvent, and subjecting the obtained mixed slurry to a first mixing to obtain a first slurry; wherein the first mixing comprises a first ultrasonic dispersion and a first mechanical mixing performed simultaneously; a mixing step: subjecting the first slurry to ball milling to obtain a second slurry; subjecting the second slurry to a second mixing to obtain a third slurry; and drying and sieving the third slurry to obtain a mixed powder; wherein the second mixing comprises a second ultrasonic dispersion and a second mechanical mixing performed simultaneously; a sintering step: subjecting the mixed powder to hot pressing and sintering, and then 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 is each independently selected from 20 to 100 min; preferably, the time for the first mixing and the second mixing is each independently selected from 20 to 60 min; preferably, during the first ultrasonic dispersion and the second ultrasonic dispersion, the ultrasonic frequency is each independently selected from 20 to 40 kHz; more preferably, during the first ultrasonic dispersion and the second ultrasonic dispersion, the ultrasonic frequency is each independently selected from 35 to 40 kHz; preferably, during the first mechanical mixing and the second mechanical mixing, the mixing speed is each independently selected from 100 to 600 rpm; more preferably, during the first mechanical mixing and the second mechanical mixing, the mixing speed is each independently selected from 150 to 350 rpm.

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

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

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

[0012] Furthermore, 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≤1 μm.

[0013] Furthermore, 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 during 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 drying time is 0.5-1.5 h.

[0015] Furthermore, the particle size of the mixed powder is 100-220 meshes; 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 provided. The alumina-based composite ceramic material is prepared by the above-mentioned method for preparing the alumina-based composite ceramic material.

[0017] The present invention provides a method for preparing an alumina-based composite ceramic material, wherein the preparation method simultaneously performs an ultrasonic dispersion operation and a mechanical mixing operation during the first mixing and second mixing processes of the pretreatment step and the mixing step. During the above-mentioned operation process, the continuous action of mechanical force can destroy the agglomerates, and the cavitation effect of the ultrasonic wave can further destroy the spontaneous agglomeration tendency caused by the inherent high surface activity of the reinforcing agent in the mixed material, and immediately eliminate the re-formed agglomeration trend. The above-mentioned continuous power input keeps the powder in a dynamic state throughout the mixing process, which can effectively prevent the occurrence of secondary agglomeration, and makes the functional raw materials such as reinforcing agents and sintering aids uniformly dispersed in the raw materials, so that they can be better integrated into the matrix material to form a finer and more uniform microstructure. In addition, the present application uses a compound of two sintering aids, and combines them with the mixing method of the above-mentioned preparation process, which is not only conducive to promoting the sintering densification of the alumina matrix, but also can further improve the interface bonding strength between the alumina and hard phase particles, thereby helping to better improve the comprehensive mechanical properties of the material. The synergistic effects of these multiple factors further ensure the uniform distribution of the reinforcement phase throughout the matrix, resulting in more uniform mechanical properties for the resulting alumina-based composite ceramic material. Furthermore, this preparation method boasts high efficiency, ease of operation, and strong controllability, offering significant advantages for the large-scale preparation of alumina-based composite ceramic materials. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0019] Figure 1 shows an SEM image of the mixed powder prepared in Example 17 of the present invention;

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

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

[0022] Figure 4 The SEM image of the mixed powder prepared in Comparative Example 1 of the present invention is shown;

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

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

[0025] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0026] As described in the background technology section, mixing and sintering alumina powder with various types of reinforcing phase materials is a classic approach to preparing high-performance alumina-based composite ceramic materials. However, the non-uniform dispersion of reinforcing agents and the like in the alumina matrix greatly weakens the uniformity of the mechanical properties of the composite ceramic materials. This defect may cause local performance failure once the composite ceramic material is subjected to high stress in a mechanically weak part, ultimately affecting the service stability and life of the entire alumina-based composite ceramic material. Therefore, how to effectively improve the soft agglomeration and hard agglomeration phenomena between 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.

[0027] In order to solve the above problems, the present invention provides a preparation method of an alumina-based composite ceramic material, which comprises the following steps: pretreatment: mixing raw materials including alumina powder, a reinforcing agent, and a sintering aid with a solvent, and subjecting the obtained mixed slurry to a first mixing to obtain a first slurry; wherein the first mixing comprises a first ultrasonic dispersion and a first mechanical mixing performed simultaneously; a mixing step: ball milling the first slurry to obtain a second slurry; subjecting the second slurry to a second mixing to obtain a third slurry; drying and sieving the third slurry to obtain a mixed powder; wherein the second mixing comprises a second ultrasonic dispersion and a second mechanical mixing performed simultaneously; a sintering step: hot pressing and sintering the mixed powder, and then cooling it to obtain an 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.

[0028] Specifically, in the above-mentioned method for preparing an alumina-based composite ceramic material, the raw materials for preparing the alumina-based composite ceramic material are first pretreated, specifically comprising: mixing raw materials for alumina powder, a reinforcing agent, and a sintering aid with a solvent; then simultaneously ultrasonically dispersing and mechanically mixing the resulting mixed slurry. The alumina powder, reinforcing agent, and sintering aid in the raw materials are fully dispersed in the solvent through the above-mentioned mixing method, thereby obtaining a first slurry with a uniform mixture. Secondly, the first slurry is ball-milled to reduce the particle size of the raw materials for preparing the alumina-based composite ceramic material while further improving the uniformity of the raw materials, such as the alumina powder, reinforcing agent, and sintering aid. The first mixed slurry obtained after ball milling is again subjected to simultaneous ultrasonic dispersion and mechanical mixing to further mix the second slurry obtained after ball milling, thereby obtaining a third mixed slurry. The fully mixed third slurry is dried and sieved to obtain a mixed powder for preparing the alumina-based composite ceramic material. Finally, the obtained mixed powder is hot-pressed and sintered, and then cooled to obtain the alumina-based composite ceramic material.

[0029] In particular, after extensive experiments, the inventors creatively discovered that by simultaneously performing ultrasonic dispersion and mechanical mixing during the pretreatment step and the first and second mixing steps, and combining two types of sintering aids, the prepared alumina-based composite ceramic material can achieve better overall performance and more uniform mechanical properties. The reasons for this may include the following:

[0030] First, ultrasonic technology utilizes the cavitation effect generated by high-frequency vibrations to rapidly break up powder particle agglomerations, promoting particle refinement and homogenization, and increasing the specific surface area and contact between the raw materials. When ultrasonic dispersion and mechanical stirring are performed simultaneously, the continuous mechanical force breaks up agglomerates, while the cavitation effect of the ultrasound further disrupts the spontaneous agglomeration tendency caused by the inherent high surface activity of the reinforcing agent in the mixed material, instantly eliminating the tendency for new agglomerations to form. This dual mechanism of action significantly improves the uniformity and dispersion efficiency of the raw materials used to prepare alumina-based composite ceramics.

[0031] Secondly, compared to using ultrasonic dispersion or mechanical mixing alone, which can lead to reagglomeration of deagglomerated powders during mixing and incomplete deagglomeration, thus affecting the dispersibility of the raw materials used to prepare alumina-based composite ceramic materials, simultaneous ultrasonic dispersion and mechanical mixing maintain dynamic powder processing throughout the mixing process, effectively preventing secondary agglomeration and further ensuring uniform distribution of the reinforcement phase throughout the matrix.

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

[0033] Fourthly, 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 a sintering aid in the process of preparing alumina-based composite ceramic materials helps to reduce the sintering temperature, and at the same time promotes the bonding between components, which is conducive to forming a dense microstructure, thereby further improving the comprehensive performance of the alumina-based composite ceramic materials. The present application will include the compound use of a sintering aid comprising a first component and a second component, which is conducive to further improving the performance of the alumina-based composite ceramic material. This is because the first component of the above-mentioned sintering aid is a metal element type sintering aid, which is easy to melt into a liquid phase during the sintering process. The liquid phase sintering aid has good wettability to the hard phase particles, and it can penetrate into the micropores and cracks of the particles and even the grain boundaries, filling in the gaps in the ceramic particle material, which is conducive to further improving the density of the alumina-based composite ceramic material and strengthening the interface bonding strength. The second component of the aforementioned sintering aid is a metal oxide-type sintering aid. This metal oxide-type sintering aid not only inhibits the growth of alumina grains, making the microstructure uniform and dense, but also reacts with alumina during the sintering process to form a second phase at the grain boundaries, producing a "pinning" effect that further improves the mechanical properties of the material. After extensive experiments, the inventors creatively discovered that compounding two sintering aids, including the first component and the second component, combined with the mixing method of the aforementioned preparation process, not only promotes the sintering and densification of the alumina matrix, but also increases the interfacial bonding strength between alumina and hard phase particles, thereby further enhancing the mechanical properties of the material.

[0034] In summary, the preparation method of the alumina-based composite ceramic material provided in the present application can fully mix the components such as the alumina powder, reinforcing agent, and sintering aid in the raw materials through simultaneous ultrasonic dispersion and mechanical mixing operations, thereby making the mechanical properties and toughness and other comprehensive properties of the prepared alumina-based composite ceramic material better. In particular, the compounding of the sintering aid comprising the first component and the second component, combined with the above-mentioned pretreatment method and mixing method, can further improve the performance of the prepared alumina-based composite ceramic material. In addition, the preparation method also has the advantages of high efficiency, simple operation, and strong controllability, especially for the large-scale preparation of alumina-based composite ceramic materials. It has obvious advantages.

[0035] In a preferred embodiment, the time for the first mixing and the second mixing is independently selected from 20 to 100 minutes. Controlling the time for the first mixing and the second mixing within the above range can make the raw materials such as alumina powder, reinforcing agent, sintering aid, etc. dispersed more evenly. Preferably, the time for the first mixing and the second mixing is independently selected from 20 to 60 minutes; the above range can make the raw materials mixed and dispersed more evenly while further improving the preparation efficiency. Preferably, during the first ultrasonic dispersion and the second ultrasonic dispersion, the ultrasonic frequency is independently selected from 20 to 40 kHz; preferably, during the first mechanical mixing and the second mechanical mixing, the mixing speed is independently selected from 100 to 600 rpm. If the ultrasonic frequency is too low, it is not conducive to the powder dispersion effect. If the ultrasonic frequency is too high, the dispersion effect cannot be further improved and unnecessary energy waste will be caused. Controlling the parameters of the ultrasonic dispersion operation and the mechanical mixing operation in the first mixing process and the second mixing process within the above range can make the raw materials for preparing the alumina-based composite ceramic material mixed more evenly. More preferably, the ultrasonic frequency during the first ultrasonic dispersion and the second ultrasonic dispersion is independently selected from 35 to 40 kHz; more preferably, the mixing speed during the first mechanical mixing and the second mechanical mixing is independently selected from 150 to 350 rpm. When the parameters for controlling the ultrasonic dispersion and mechanical mixing operations during the first mixing and the second mixing are within the above preferred ranges, the above effects are further improved.

[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. Maintaining the ratio within this range facilitates a better synergistic effect between the first and second components, 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. Maintaining the ratio within this preferred range further enhances the aforementioned effects and results in a better performance of the resulting alumina-based composite ceramic material.

[0037] In a preferred embodiment, the raw materials include, by weight, 45 to 80 parts of alumina powder, 15 to 50 parts of a reinforcing agent, and 0.5 to 6.5 parts of a sintering aid. In the process of preparing the alumina-based composite ceramic material, by controlling the ratio of alumina powder to reinforcing agent and sintering aid within the above range, the mechanical properties and toughness of the prepared alumina-based composite ceramic material can be made better. Preferably, the reinforcing agent is one or more of TiC, TiN and Ti(C,N). The above-mentioned types of reinforcing agents can better play their role, which is conducive to further improving the mechanical properties of the alumina-based composite ceramic material, and thus is conducive to extending the service life of the alumina-based composite ceramic material. In particular, the above-mentioned reinforcing agent and the sintering aid provided by the present invention can work together to 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 range can better play the role of the reinforcing agent, which is conducive to further improving the comprehensive performance of the alumina-based composite ceramic material. Preferably, the reinforcing agent is at least two of TiC, TiN, and Ti(C,N). Under the above conditions, the performance of the alumina-based composite ceramic material is better.

[0038] In a preferred embodiment, the ball milling speed is 250-500 rpm and the milling time is 12-48 hours. Controlling the ball milling speed and milling time within the above parameter ranges can improve the uniformity of the prepared alumina-based composite ceramic material, which is conducive to further improving the uniformity of the mechanical properties and density 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 minutes, and the hot-pressing sintering pressure is 25-35 MPa. Preferably, the vacuum level during the hot-pressing sintering process is 5-100 Pa. Controlling the sintering process parameters within the above ranges is beneficial for improving the mechanical properties of the prepared alumina-based composite ceramic material.

[0040] In a preferred embodiment, drying is rotary evaporation drying; the third slurry obtained is dried by rotary evaporation drying. This drying process can keep the powder in a dynamically dispersed state, effectively alleviating the re-adhesion between particles caused by the rapid evaporation of the solvent during the drying process, that is, the secondary agglomeration phenomenon. While increasing the drying rate, the above method can also effectively overcome the viscosity problem that may be caused by conventional drying methods, help to maintain the uniformity of the slurry composition, and avoid performance inconsistency caused by uneven drying. Preferably, the vacuum degree of the drying process is 150 to 200 mbar; preferably, the drying temperature is 50 to 70°C, and the time is 0.5 to 1.5 hours. Carrying out the above rotary evaporation drying operation under vacuum conditions and controlling the drying temperature and drying time within the above range 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, can make the first slurry more uniformly mixed.

[0042] According to another aspect of the present invention, an alumina-based composite ceramic material is also provided, which is prepared by the above-mentioned 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 specificity of the materials field and the limitations of existing testing and characterization methods, it is impossible to fully characterize the materials obtained by the above preparation method. However, experiments have confirmed that the alumina-based composite ceramic material can improve the stability of its mechanical properties, demonstrating that the preparation method of the present invention improves the material itself.

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

[0045] Example 1

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

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

[0048] Mixing step: The first slurry was ball milled at 400 rpm for 24 hours to obtain a second slurry. The second slurry was placed in an ultrasonic agitator for simultaneous ultrasonic dispersion and mechanical mixing to obtain a third slurry. The third slurry was dried on a rotary evaporator 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. The ultrasonic frequency was 40 kHz, the mechanical mixing speed was 300 rpm, and the mixing time was 30 minutes.

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

[0050] Example 2

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

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

[0053] Mixing step: The first slurry was ball milled at 400 rpm for 24 hours to obtain a second slurry. The second slurry was placed in an ultrasonic agitator for simultaneous ultrasonic dispersion and mechanical mixing to obtain a third slurry. The third slurry was dried on a rotary evaporator at 60°C and 170 mbar for 1 hour, and then sieved to obtain a mixed powder with a particle size of less 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 mixed powder obtained above is placed in a graphite mold and hot-pressed under a vacuum of 100 Pa. The product is then cooled to room temperature to obtain an alumina-based composite ceramic material. The hot-pressing sintering temperature is 1650°C, the sintering time is 20 minutes, and the pressure is 30 MPa.

[0055] Example 3

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

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

[0058] Mixing step: The first slurry was ball milled at 400 rpm for 24 hours to obtain a second slurry. The second slurry was placed in an ultrasonic agitator for simultaneous ultrasonic dispersion and mechanical mixing to obtain a third slurry. The third slurry was dried on a rotary evaporator at 60°C and 170 mbar for 1 hour, and then sieved to obtain a mixed powder with a particle size of less 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 mixed powder obtained above is placed in a graphite mold and hot-pressed under a vacuum of 100 Pa. The product is then cooled to room temperature to obtain an alumina-based composite ceramic material. The hot-pressing sintering temperature is 1650°C, the sintering time is 20 minutes, and the pressure is 30 MPa.

[0060] Example 4

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

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

[0063] Mixing step: The first slurry was placed in a ball mill and milled at 500 rpm for 12 hours to obtain a second slurry. The second slurry was placed in an ultrasonic agitator and subjected to simultaneous ultrasonic dispersion and mechanical mixing to obtain a 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 with a mesh size of less than 100. The ultrasonic frequency was 20 kHz, the mechanical mixing speed was 100 rpm, and the mixing time was 100 minutes.

[0064] Sintering step: The mixed powder obtained above is placed in a graphite mold and hot-pressed and sintered 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°C, the sintering time is 120 minutes, and the sintering pressure is 25 MPa.

[0065] Example 5

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

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

[0068] Mixing step: The first slurry was placed in a ball mill and milled at 250 rpm for 48 hours to obtain a second slurry. The second slurry was placed in an ultrasonic agitator and subjected to simultaneous ultrasonic dispersion and mechanical mixing to obtain a 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 with a mesh size of less than 100. The ultrasonic frequency was 30 kHz, the mechanical mixing speed was 600 rpm, and the mixing time was 100 minutes.

[0069] Sintering step: The mixed powder obtained above is placed in a graphite mold and hot-pressed and sintered 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°C, the sintering time is 20 minutes, and the 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 components for preparing the alumina-based composite ceramic material are: Al2O3-TiC-TiN-Ni-MgO. Specifically, by weight, they include: 45 parts of alumina powder, 50 parts of a reinforcing agent (comprising 30 parts of TiC powder and 20 parts of TiN powder), and 5 parts of a sintering aid (comprising 3 parts of Ni powder and 2 parts of MgO powder).

[0080] Example 11

[0081] Example 11 differs from Example 1 in that the raw material components for preparing the alumina-based composite ceramic material are: Al2O3-TiC-TiN-Ni-MgO. Specifically, by weight, these components include: 80 parts alumina powder, 15 parts reinforcing agent (comprising 10 parts TiC powder and 5 parts TiN powder), and 5 parts sintering aid (comprising 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 components for preparing the alumina-based composite ceramic material are: Al2O3-TiC-TiN-Ni-MgO. Specifically, by weight, they include: 50 parts of alumina powder, 43.5 parts of a reinforcing agent (including 29 parts of TiC powder and 14.5 parts of TiN powder), and 6.5 parts of a sintering aid (including 4 parts of Ni powder and 2.5 parts of MgO powder).

[0084] Example 13

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

[0086] Example 14

[0087] The difference between Example 14 and Example 1 is that the raw material components for preparing the alumina-based composite ceramic material are: Al2O3-TiC-Co-MgO. Specifically, by weight, they include: 59 parts of alumina powder, 38 parts of reinforcing TiC powder, and 3 parts of a 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 components for preparing the alumina-based composite ceramic material are: Al2O3-TiN-Ni-Y2O3. Specifically, by weight, they include: 59 parts of alumina powder, 38 parts of reinforcing TiN powder, and 3 parts of a sintering aid (including 2 parts of Ni powder and 1 part of Y2O3 powder).

[0090] Example 16

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

[0092] Example 17

[0093] The difference between Example 17 and Example 1 is that the raw material components for preparing the alumina-based composite ceramic material are: Al2O3-TiC-TiN-Ni-Mo-MgO. Specifically, by weight, they include: 57.5 parts of alumina powder, 37 parts of a reinforcing agent (including 29 parts of TiC powder and 8 parts of TiN powder), and 5.5 parts of a 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 that during the pretreatment, the ultrasonic frequency is 10 Hz, the mechanical mixing speed is 250 rpm, and the mixing time is 10 minutes. In the mixing step, the ultrasonic frequency is 10 Hz, the mechanical mixing speed is 250 rpm, and the mixing time is 5 minutes.

[0096] Comparative Example 1

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

[0098] 57.5 parts of alumina powder, 37 parts of a reinforcing agent (including 29 parts of TiC powder and 8 parts of TiN powder), and 5.5 parts of a sintering aid (including 2.2 parts of Ni powder, 2.5 parts of Mo powder, and 0.8 parts of MgO powder) were mixed with anhydrous ethanol. The resulting mixture was placed in a ball mill and milled at 400 rpm for 24 hours to obtain a second slurry with a solid content of 20%. The resulting 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. The resulting mixed powder was placed in 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 sintering time was 20 minutes, and the sintering pressure was 30 MPa.

[0099] Comparative Example 2

[0100] The raw material components for preparing alumina-based composite ceramic materials are: 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 mix them with anhydrous ethanol. The resulting mixture is first mechanically mixed and stirred at a speed of 250 rpm for 30 minutes, and then ultrasonically dispersed at an ultrasonic frequency of 40 Hz for 30 minutes to obtain a first slurry with a solid content of 20%.

[0102] Mixing step: Place the first slurry in a ball mill and mill at 400 rpm for 24 hours to obtain a second slurry. The obtained second slurry is 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 mixed powder obtained above is placed in a graphite mold and hot-pressed under a vacuum of 100 Pa. The product is then cooled to room temperature to obtain an alumina-based composite ceramic material. The hot-pressing sintering temperature is 1650°C, the sintering time is 20 minutes, and the pressure is 30 MPa.

[0104] Comparative Example 3

[0105] The raw material components for preparing alumina-based composite ceramic materials are: 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 mix them with anhydrous ethanol. The resulting mixture is first ultrasonically dispersed at an ultrasonic frequency of 40 Hz for 30 minutes, and then mechanically mixed and stirred at a speed of 250 rpm for 30 minutes to obtain a first slurry with a solid content of 20%.

[0107] Mixing step: Place the first slurry in a ball mill and mill at 400 rpm for 24 hours to obtain a second slurry. The obtained second slurry is 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 mixed powder obtained above is placed in a graphite mold and hot-pressed under a vacuum of 100 Pa. The product is then cooled to room temperature to obtain an alumina-based composite ceramic material. The hot-pressing sintering temperature is 1650°C, the sintering time is 20 minutes, and the pressure is 30 MPa.

[0109] Comparative Example 4

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

[0111] Comparative Example 5

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

[0113] For the ceramic materials prepared in the above embodiments and comparative examples, three areas of the same sample were selected and cut and surface-polished with diamond wire to obtain three samples with specifications of 20mm×4mm×3mm, named as Sample 1, Sample 2 and Sample 3. The sample selection positions in each embodiment or comparative example are consistent. First, the flexural strength of the above samples was tested respectively, and the average flexural strength and standard deviation were calculated based on the test data. The results are shown in Table 1. Among them, the average flexural strength can reflect the overall strength level of the ceramic material prepared in the embodiment, that is, the average bearing capacity of the material when subjected to bending force; the standard deviation of the flexural strength can reflect the degree of strength dispersion of the ceramic material prepared in the corresponding embodiment. 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 10mm and a loading rate of 0.5mm / min. The specific test steps refer to GB / T 6569-2006;

[0115] The calculation method of the standard deviation of flexural strength includes: calculating the standard deviation according to the following formula: (where σ is the standard deviation, x i is the flexural strength of each sample, and μ is the average flexural strength).

[0116] Table 1

[0117]

[0118]

[0119] In order 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. The specific test methods are as follows:

[0120] Fracture toughness test: The fracture toughness of the sample was tested using the single-edge notched beam method with a span of 10 mm, a notch size of 1.8 ± 0.32 mm, and a loading rate of 0.05 mm / min. The specific test method is in accordance with GB / T 23806-2009.

[0121] Hardness test: A 20 mm × 4 mm × 3 mm sample was polished and indented using a Vickers hardness tester with a load of 500 gf and a hold time of 15 seconds. For specific test methods, refer to GB / T 16534-2009.

[0122] Table 2

[0123]

[0124]

[0125] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0126] In Examples 1 to 18, when preparing alumina-based composite ceramic materials, ultrasonic dispersion operations and mechanical mixing operations were performed simultaneously in the first mixing and second mixing processes in the pretreatment step and the mixing step, and two types of sintering aids were compounded and used. According to the results in Tables 1 and 2, the average flexural strength and standard deviation of the flexural strength, as well as the fracture toughness and hardness of the alumina-based composite ceramic materials prepared in the above examples are all at a good level, and the mechanical properties of the corresponding alumina-based composite ceramic materials are good. In addition, the standard deviation of the corresponding alumina-based composite ceramic materials is small, indicating that the strength dispersion of the corresponding ceramic materials is small, the flexural strength is relatively uniform, and the uniformity of the mechanical properties is better. In particular, in Examples 1 to 17, the parameters in the preparation process are controlled within the preferred range, and the mechanical properties and distribution uniformity of the corresponding alumina-based composite ceramic materials are more effectively improved. In Comparative Examples 1 to 3, the treatment method provided by the present application was not used during the preparation process. The average flexural strength and standard deviation of the flexural strength, as well as the fracture toughness and hardness of the prepared alumina-based composite ceramic materials are relatively poor, and the uniformity of the mechanical property distribution is significantly different from that of the examples of the present application. In Comparative Examples 4 and 5, although the treatment method provided in the present application was adopted, 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 comprehensive performance of the corresponding alumina-based composite ceramic material also had a large gap compared with the embodiments of the present application.

[0127] In order to further explore the performance of the prepared alumina-based composite ceramic material, the mixed powders prepared in Example 17 and Comparative Example 1 were selected and their microscopic morphologies were tested. Figure 1 、 Figure 2 、 Figure 3 The SEM image, the energy spectrum of Al element, and the energy spectrum of Ti element of the mixed powder prepared in Example 17 of the present invention are shown respectively; Figures 1 to 3 It can be seen that in the first mixing and second mixing processes in the pretreatment step and the mixing step, ultrasonic dispersion operation and mechanical mixing operation are performed simultaneously, and the dispersion of the reinforcing phase in the alumina-based composite powder in the matrix is ​​significantly improved. Figure 4 、 Figure 5 、 Figure 6 The SEM image, the energy spectrum of Al element, and the energy spectrum of Ti element of the mixed powder prepared in Comparative Example 1 of the present 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. This shows that the treatment method in the preparation method of the alumina-based composite ceramic material provided in this application can effectively improve the dispersion of the components in the alumina-based composite ceramic material, thereby effectively improving the comprehensive performance of the aluminum-based composite ceramic material.

[0128] In summary, the preparation method of the alumina-based composite ceramic material provided by the present application simultaneously performs ultrasonic dispersion operation and mechanical mixing operation in the pretreatment step and the first mixing and second mixing processes of the mixing step, which can effectively improve the mechanical properties and uniformity of the mechanical properties of the prepared alumina-based composite ceramic material. The compounding of the two sintering aids and the combination of the treatment method of the above-mentioned preparation process are conducive to better promoting the sintering densification of the alumina matrix and improving the interface bonding strength between alumina and hard phase particles. The mechanical properties and uniformity of the mechanical properties of the prepared alumina-based composite ceramic material are better, and the comprehensive mechanical properties of the alumina-based composite ceramic material are better.

[0129] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be 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 comprises the following steps: Pretreatment: mixing raw materials including alumina powder, a reinforcing agent, and a sintering aid with a solvent, and subjecting the obtained mixed slurry 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 step: ball milling the first slurry to obtain a second slurry; subjecting the second slurry to a second mixing to obtain a third slurry; drying and sieving the third slurry to obtain a mixed powder; wherein the second mixing includes a second ultrasonic dispersion and a second mechanical mixing performed simultaneously; Sintering step: hot pressing and sintering the mixed powder, and then cooling to obtain the alumina-based composite ceramic material; The sintering aid includes 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.

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

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

5. The method for preparing an alumina-based composite ceramic material according to any one of claims 1 to 3, characterized in that: The ball milling speed is 250-500 rpm, and the time is 12-48 hours.

6. The method for preparing an 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≤1 μm.

7. The method for preparing an 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°C, the hot pressing sintering time is 20-120 minutes, and the hot pressing sintering pressure is 25-35 MPa; And / or, the vacuum degree during the hot pressing sintering process is 5-100 Pa.

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

9. The method for preparing an 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 to 220 mesh; and / or, the solid content of the first slurry is 5 to 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 an alumina-based composite ceramic material according to any one of claims 1 to 9.

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