High-performance nano-laminated aluminum oxide ceramic material and preparation method thereof

Abstract

The invention discloses a high-performance nano-laminated aluminum oxide ceramic material and a preparation method thereof, and relates to the field of ceramic materials, the nano-laminated aluminum oxide ceramic material prepared by the method has a high-density laminated structure inside, and is located in a grain boundary region; the thickness of a fault area of a grain boundary area is 5-50nm; the grain size of the material is between 0.1 mu m and 2 mu m; the crystal structure of the material is alpha-Al2O3. The nanometer staggered aluminum oxide ceramic material synthesized by the method has the characteristics of higher density, bending strength, high hardness and high fracture toughness, and has a wide application prospect.

Description

Technical Field

[0001] The invention belongs to the field of ceramic materials, and in particular relates to a high-performance nano stacking fault alumina ceramic material and a preparation method thereof. Background Art

[0002] Alumina ceramics are a widely used structural ceramic material with the advantages of high hardness, high melting point, wear resistance, chemical corrosion resistance and good thermal conductivity. They can be widely used in aerospace, military, medical and other fields. With the development of science and technology, the requirements for material performance are becoming more and more stringent. Using ceramic materials to replace traditional metal materials has become a trend. However, the mechanical properties of alumina ceramics prepared by existing traditional methods are relatively low. Specifically, they are as follows: (1) The prepared grain size is uneven and the distribution range is large, which affects the mechanical properties and electrical conductivity of the material; (2) The process is complex, the production cycle is long, and the cost is high. At the same time, the high-temperature sintering process will cause the size and shape of the material to change, making it difficult to control the accuracy and consistency of the material; (3) The performance in terms of thermal conductivity, thermal stability and corrosion resistance needs to be improved, which affects the application expansion of oxide ceramics.

[0003] Moreover, in order to obtain higher performance alumina ceramic materials, the current method is mainly to further increase the relative density after sintering and control the relative density after sintering and control the grain size of alumina ceramics after sintering. In terms of regulating the flexural strength of alumina ceramics, the adjustment space is limited, and the flexural strength of the prepared alumina package ranges from 300-500MPa. At the same time, nanoscale alumina ceramics are difficult to prepare, the process is cumbersome, and the energy consumption is huge. Summary of the invention

[0004] In view of the defects and problems of traditionally prepared alumina ceramic materials, such as low bending strength, complicated process, huge energy consumption, and weak physical and mechanical properties, the present invention provides a high-performance nano-stacked alumina ceramic material and a preparation method thereof.

[0005] The solution adopted by the present invention to solve its technical problems is: a high-performance nano-stacked alumina ceramic material, wherein the nano-stacked alumina ceramic material has a high-density stacking fault structure inside, which is located in the grain boundary area; the thickness of the stacking fault zone in the grain boundary area is between 5-50nm; the grain size of the material is between 0.1-2μm; and the crystal structure of the material is α-Al2O3.

[0006] The present invention also provides a method for preparing the above-mentioned high-performance nano-stacked alumina ceramic material, comprising the following steps: S1, using alumina ceramic powder with a particle size of 50-300nm and a purity greater than 99% as a raw material, preparing a porous alumina ceramic body by pre-sintering; S2, sintering and forging the porous alumina ceramic body at a temperature of 1250-1400° C. and a dynamic pressure median pressure of 20-100 MPa to promote bonding between particles and deformation of grain boundary regions; S3. After sintering and forging, high-temperature pressure relief treatment is performed to obtain high-performance nano-stacked alumina ceramic materials.

[0007] Furthermore, the relative density of the porous alumina ceramic body is 65-80%.

[0008] Furthermore, the pre-sintering synthesis method is: placing the pre-pressed raw material and the graphite mold into a vacuum sintering device for sintering without external pressure, and maintaining the temperature at 1250-1400° C. for 50-80 minutes.

[0009] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a high-performance nano-stacked alumina ceramic material and a preparation method thereof, which realizes grain boundary strengthening through transformation at the grain boundaries, thereby greatly improving the mechanical properties of the material, and provides a new approach and method for improving the mechanical properties of existing alumina ceramics.

[0010] The nano-stacked alumina ceramic material prepared by the method of the present invention has a hardness of 19-21.8 GPa and a fracture toughness of 3.5-5.3 MPa.m 1 / 2 The bending strength reaches 550-770MPa, and the material contains a high-density stacking fault structure in the grain boundary area. The thickness of the stacking fault area in the grain boundary area is 5-50nm, which has better physical and mechanical properties.

[0011] The pressure effect during the dynamic sintering and forging process of the present invention can make the particles more tightly bonded, improve the density of the material, realize repeated deformation at the grain boundary to produce nano-stacked fault zones at the grain boundary, thereby enhancing the strength and hardness of the material, and can be suitable for application fields requiring high strength and wear resistance; and the dynamic sintering and forging method can complete the material preparation process in a relatively short time, effectively improve production efficiency and reduce costs; the nano-stacked fault alumina ceramic material prepared by the method of the present invention has the characteristics of high density, bending strength, high hardness and high fracture toughness, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 These are the transmission electron microscope morphology image and high-resolution image of the nano-stacked alumina ceramic material prepared by the present invention. Implementation

[0013] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0014] See also Figure 1 The present invention provides a high-performance nano-stacked alumina ceramic material and a technical solution for its preparation method. The nano-stacked alumina ceramic material prepared by the method of the present invention has a hardness of 19-21.8 GPa and a fracture toughness of 3.5-5.3 MPa.m 1 / 2 The bending strength reaches 550-770 MPa, and the material contains a high-density stacking fault structure in the grain boundary region. The thickness of the stacking fault region in the grain boundary region is 5-50nm. It has the characteristics of high density, bending strength, high hardness and high fracture toughness. Example

[0015] This embodiment provides a method for preparing a nano-alumina ceramic material, using dynamic sintering and forging, including the following steps: S1. Use alumina powder as raw material and pre-press and shape: Weigh 13g of alumina powder with an average particle size of 170nm and put it into a Φ30mm graphite mold and pre-press it with a certain pressure; S2. Preparing a porous alumina ceramic body by pre-sintering, that is, performing heat treatment at a certain temperature to allow powder particles to combine to form a porous alumina ceramic body.

[0016] The pre-sintering synthesis method in this embodiment is: putting the pre-pressed raw material and the graphite mold into a vacuum sintering device, maintaining vacuum without external pressure for sintering, and keeping the temperature at 1250° C. for 60 minutes.

[0017] S3, sintering and forging the porous alumina ceramic body at a certain temperature and dynamic pressure: The porous alumina ceramic body has a relative density of 71% and is subjected to dynamic sintering and forging. The applied temperature is 1300°C, the median pressure is 100MPa, the amplitude is 10MPa, the frequency is 5Hz, and the dynamic force is maintained for 60min after the temperature is raised to 1300°C. During the sintering and forging process, the porous alumina ceramic body undergoes crystal rearrangement and combination, and grain boundary deformation occurs by controlling the temperature and pressure, forming a high-performance nano-stacked alumina ceramic material.

[0018] S4, cooling and pressure relief: After sintering and forging, high-temperature pressure relief treatment is carried out. High-temperature pressure relief can reduce or eliminate the applied pressure at high temperature, so that the material can be relaxed and stabilized; after high-temperature pressure relief, a uniform high-performance nano-stacked alumina ceramic material can be obtained, which has high density, high strength and excellent physical and chemical properties.

[0019] The high-performance nano-stacked alumina ceramic material prepared by the method of this embodiment has a relative density of 99.8%, a hardness of 20.5 GPa, and a fracture toughness of 3.9 MPa.m 1 / 2 The bending strength is 770 Mpa. The high-performance nano-stacked alumina ceramic material prepared in this embodiment contains a high-density stacking fault structure in the grain boundary region, the thickness of the stacking fault region in the grain boundary region is 5-50 nm, and the grain size is 0.1-2 μm. Example

[0020] The preparation method of the nano-alumina ceramic material provided in this embodiment adopts dynamic sintering and forging, and comprises the following steps: S1. Use alumina powder as raw material and pre-press and shape: Weigh 13g of alumina powder with an average particle size of 300nm and put it into a Φ30mm graphite mold to give a certain pressure for pre-pressing; S2. Preparing a porous alumina ceramic body by pre-sintering: The pre-sintering synthesis method in this embodiment is: putting the pre-pressed raw material and the graphite mold into a vacuum sintering device to maintain vacuum without external pressure for sintering, and keeping the temperature at 1400° C. for 50 minutes.

[0021] S3, sintering and forging the porous alumina ceramic body at a certain temperature and dynamic pressure: The porous alumina ceramic body has a relative density of 78% and is subjected to dynamic sintering and forging. The applied temperature is 1300°C, the median pressure is 100 MPa, the amplitude is 10 MPa, the frequency is 5 Hz, and the dynamic force is maintained for 60 minutes after the temperature is raised to 1300°C.

[0022] S4, cooling and pressure relief: After cooling and releasing the pressure, uniform high-performance nano-stacked alumina ceramic material can be obtained.

[0023] The high-performance nano-stacked alumina ceramic material prepared in this embodiment has a relative density of 99.8%, a hardness of 19.8 GPa, and a fracture toughness of 4.1 MPa.m 1 / 2 , the flexural strength is 600 MPa. Example

[0024] This embodiment provides a method for preparing a nano-alumina ceramic material, using dynamic sintering and forging, including the following steps: S1. Use alumina powder as raw material and pre-press and shape: Weigh 13g of alumina powder with an average particle size of 300nm and put it into a Φ30mm graphite mold to give a certain pressure for pre-pressing; S2. Preparing a porous alumina ceramic body by pre-sintering: The pre-sintering synthesis method in this embodiment is: putting the pre-pressed raw material and the graphite mold into a vacuum sintering device to maintain vacuum without external pressure for sintering, and keeping the temperature at 1300° C. for 80 minutes.

[0025] S3, sintering and forging the porous alumina ceramic body at a certain temperature and dynamic pressure: In the above step 2, the porous alumina ceramic body has a relative density of 78% and is subjected to dynamic sintering and forging. The applied temperature is 1400°C, the median pressure is 80 MPa, the amplitude is 10 MPa, the frequency is 5 Hz, and the dynamic force is maintained for 60 minutes after the temperature is raised to 1400°C.

[0026] S4, cooling and pressure relief: After cooling and releasing the pressure, uniform high-performance nano-stacked alumina ceramic material can be obtained.

[0027] The high-performance nano-stacked alumina ceramic material prepared in this embodiment has a relative density of 99.8%, a hardness of 19.0 GPa, and a fracture toughness of 4.4 MPa.m 1 / 2 , the flexural strength is 550 MPa.

[0028] The above description is only a preferred embodiment of the present invention and does not limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A high-performance nano-stacked alumina ceramic material, characterized by: The nano-stacked alumina ceramic material has a high-density stacking fault structure inside, which is located in the grain boundary area; the thickness of the stacking fault area in the grain boundary area is between 5-50nm; the grain size of the material is between 0.1-2μm; and the crystal structure of the material is α-Al2O3.

2. A method for preparing a high-performance nano-stacked alumina ceramic material as claimed in claim 1, characterized in that: The following steps are involved: S1, using alumina ceramic powder with a particle size of 50-300nm and a purity greater than 99% as a raw material, preparing a porous alumina ceramic body by pre-sintering; S2, sintering and forging the porous alumina ceramic body at a temperature of 1250-1400° C. and a dynamic pressure median pressure of 20-100 MPa to promote bonding between particles and deformation of grain boundary regions; S3. After sintering and forging, high-temperature pressure relief treatment is performed to obtain high-performance nano-stacked alumina ceramic materials.

3. The method for preparing a high-performance nano-stacked alumina ceramic material according to claim 2, characterized in that: The relative density of the porous alumina ceramic body is 65-80%.

4. The method for preparing a high-performance nano-stacked alumina ceramic material according to claim 2, characterized in that: The pre-sintering synthesis method comprises: placing the pre-pressed raw material and the graphite mold into a vacuum sintering device for sintering without external pressure, and maintaining the temperature at 1250-1400° C. for 50-80 minutes.

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