Stable zirconia high-toughness ceramic and preparation method thereof

Abstract

The invention discloses stable zirconia high-toughness ceramic and a preparation method thereof.The stable zirconia high-toughness ceramic comprises a base material, a reinforcing phase and an interface transition zone, the base material is Y2O3-ZrO2 nano powder, the reinforcing phase comprises compact layers and porous layers which are alternately distributed, the compact layers enable alumina whiskers to be radially distributed in the radial direction, and the porous layers enable the alumina whiskers to be evenly distributed in the radial direction; a crystal whisker-nano particle-matrix three-stage toughening network is formed, a porous layer contains beta-Si3N4 crystal whiskers generated in situ, and an interface transition region is a ZrO2-beta-Si3N4 eutectic layer. According to the invention, the whisker is added, the fracture energy is consumed through the pull-out effect, the nano-particles inhibit crack propagation through the pinning effect, the matrix phase change is toughened, the fracture toughness of the ceramic is improved, and the crack propagation path is prolonged by 3-5 times. On the other hand, the sintering temperature is reduced, so that energy consumption is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of ceramic materials, and in particular to a stabilized zirconia high-toughness ceramic and a preparation method thereof. Background Art

[0002] With the rapid development of science and technology, consumers have higher and higher requirements for the performance and quality of ceramic materials. Zirconia ceramics have a wide range of applications due to their better corrosion resistance, higher hardness, and higher strength than other types of ceramics. However, when making large-area appearance parts, although the toughness of existing zirconia ceramics (reaching 5-6MPa·m 1 / 2 ) is higher than other types of ceramics, but still has the disadvantage of not being resistant to falling.

[0003] At present, yttrium-stabilized zirconia powder is relatively mature on the market, and the improvement of zirconia ceramics is usually based on yttrium-stabilized zirconia powder. In order to improve the toughness of zirconia ceramics, conventional toughening methods include: causing zirconia ceramics to undergo phase change, or adding a second structural phase to zirconia ceramics for toughening. For example, a Mg-stabilized TZP ceramic is disclosed in Chinese patent CN021111464. This ceramic can achieve a partial toughening effect by doping with Mg, but the effect is not obvious. Moreover, the strength of the ceramic samples prepared by this method is relatively low, only about 590MPa, and such strength cannot be used to prepare large-area thin sheets.

[0004] Zirconia ceramics are mostly prepared using organic zirconium sources (such as zirconium ethanol and zirconium tert-butoxide), which are not only expensive, but also need to react in organic solvents, resulting in complex processes, environmental pollution, and harsh operating conditions. Zirconia ceramics using stabilizers such as magnesium oxide and calcium oxide need to be sintered at high temperatures of 1700-1800°C, which can easily lead to grain coarsening, ceramic cracking, and poor thermal stability. Traditional zirconia ceramics often face a contradiction between strength and toughness. For example, although Ce-TZP has high toughness (15-20 MPa·m¹ / ²), its strength is only 300-600 MPa; while Y-TZP can reach a strength of 1200 MPa, but its toughness is relatively low. Summary of the invention

[0005] Purpose of the invention: The purpose of the present invention is to provide a stable zirconia high-toughness ceramic and a preparation method thereof. In the present invention, whiskers are added to consume fracture energy through the pull-out effect, nanoparticles inhibit crack propagation through the pinning effect, and the matrix is ​​phase-transformed and toughened, thereby improving the fracture toughness of the ceramic and extending the crack propagation path by 3 to 5 times. On the other hand, the sintering temperature is reduced to reduce energy consumption.

[0006] Technical solution: A stable zirconia high-toughness ceramic, including a matrix material, a reinforcement phase, and an interface transition zone; Among them, the matrix material is Y2O3-ZrO2 nanopowder with a particle size of 20-100 nm; The reinforcing phase includes alternately distributed dense layers and porous layers, as Figure 2 shown; The dense layer is formed by the radial radial distribution of alumina whiskers, forming a "whisker-nanoparticle-matrix" three-stage toughening network; The porous layer contains in-situ generated β-Si3N4 whiskers, including ZrOCl2·8H2O, Y(NO3)3·6H2O, Si(NH)2, pore template agent pores, and the interlayer angle is controlled at 45°±5° through a multi-channel extrusion device; The interface transition zone is a ZrO 2- β-Si3N4 eutectic layer.

[0007] Preferably, the preparation method of the matrix material: Prepare a mixed solution of ZrOCl2·8H2O and YCl3 according to the proportion of 3% mass fraction of yttrium oxide, dropwise add a mixed solution of ammonia water and hydrogen peroxide to the solution under stirring, adjust the pH of the solution to about 6, add absolute ethanol to the reaction system, control the end point pH to about 10, react for about 90 min, let it stand for precipitation, wash with absolute ethanol and acetone, and calcine at 600 °C to obtain the product 3mol%Y2O3-ZrO2 nanopowder.

[0008] Preferably, the preparation of the dense layer: Prepare a 0.2mol / L Al(NO3)3 solution according to the proportion of 3% mass fraction of Al2O3, add absolute ethanol and PEG, add Y2O3-ZrO2 nanopowder to the solution and stir and ultrasonically disperse to form a suspension, dropwise add ammonia water to pH 8.5, filter, wash, dry, tape casting, and calcine at 1250 °C to obtain the dense layer.

[0009] Preferably, the preparation of the porous layer: Ball-mill and mix the ZrOCl2·8H2O, Y(NO3)3·6H2O and Si(NH)2 precursors in a mass ratio of 85:5:10, add 0.5wt% polyvinylpyrrolidone PVP as the pore template agent, and prepare a green body with alternately dense and porous layers through a multi-channel extrusion device, and generate Si3N4 whiskers in a nitrogen atmosphere at 850-900 °C for 2 h of pre-calcination.

[0010] Preferably, submicron alumina whiskers with a gradient distribution are introduced into the dense layer, with a diameter of 0.2-0.5 μm and an aspect ratio of 10-15.

[0011] Preferably, the in-situ generated β-Si3N whiskers in the porous layer have an aspect ratio of ≥20, the thickness ratio of the dense layer to the porous layer is 1:(0.8-1.2), and the porosity of the porous layer is 15-20%.

[0012] A preparation method of a stabilized zirconia high-toughness ceramic, comprising the following steps: S1. Prepare a matrix material, a dense layer, and a porous layer, and prepare a laminated green body by multi-channel tape casting; S2. Reaction sintering: In the first stage, pre-sinter at 850 - 900 °C for 2 h in a nitrogen atmosphere to generate Si3N4 whiskers, and a solid-phase reaction of Al2O3 and surface defects of ZrO2 generates a transition layer. In the second stage, microwave sinter at 1250 °C, apply an axial pressure of 5 MPa, and keep the temperature for 30 min to generate alumina whiskers, and a solid-phase reaction of Si3N4 whiskers and surface defects of ZrO2 generates ZrO 2- β-Si3N4 eutectic layer. In the third stage, introduce argon gas for cooling in the later stage of sintering. Beneficial effects

[0013] In the present invention, by preparing Y2O3-ZrO2 nanopowders and introducing gradient-distributed submicron alumina whiskers into the matrix, the alumina whiskers are radially distributed in a radial manner to form a "whisker-nanoparticle-matrix" three-stage toughening network. The whiskers consume fracture energy through the pull-out effect, the nanoparticles inhibit crack propagation through the pinning effect, and matrix phase transformation toughening (t→m phase transformation). The fracture toughness and flexural strength are enhanced more than those of conventional 3Y-TZP. Applying the ceramic material described in the present invention to cutting tools, molds, wear-resistant parts, engine components, etc. can effectively improve the service performance.

[0014] In the porous layer of the present invention, in-situ generated β-Si3N4 whiskers are contained, and the interface transition zone is a ZrO2-β-Si3N4 eutectic layer, which prolongs the crack propagation path of the ceramic material and enhances the fracture toughness and flexural strength. Applying the ceramic material described in the present invention to cutting tools, molds, wear-resistant parts, armor, etc. can greatly improve its fracture toughness.

[0015] The present invention adopts low-temperature reaction sintering, which reduces the sintering temperature by 150 - 200 °C compared with traditional sintering, reduces production energy consumption, and by adopting this sintering method, the flexural strength of the ceramic material is enhanced. Description of the drawings

[0016] Figure 1 It is the SEM image of alumina whiskers; Figure 2 It is the schematic diagram of the alternating structure of the dense layer and the porous layer; Figure 3 It is the SEM image of the interface transition zone. Specific embodiments

[0017] To make the technical solutions of the present invention clearer, the following further describes the present invention in detail with specific embodiments. Embodiment 1

[0018] A high-toughness stabilized zirconia ceramic is obtained by the following preparation method: (1) Preparation of matrix material: Add 507.4 g of ZrOCl₂·8H₂O and 5.2 g of YCl₃ to 4 L of water to dissolve them completely. While stirring, dropwise add a mixed solution of ammonia water and hydrogen peroxide, adjust the pH of the solution to about 6, add 6 L of absolute ethanol to the reaction system, control the final pH to about 10, stir and react for about 90 min, let it stand for precipitation, wash with absolute ethanol and acetone, and calcine at 600 °C to obtain 3 mol% Y₂O₃-ZrO₂ nanopowder as the product; (2) Preparation of dense layer: Take 147 ml of 0.2 mol / L Al(NO₃)₃ solution, add 220 ml of absolute ethanol and 10 g of PEG, stir, add 97 g of Y₂O₃-ZrO₂ nanopowder to the solution, stir and disperse ultrasonically to form a suspension, dropwise add ammonia water until the pH reaches 8.5, filter, wash, dry, and perform tape casting; (3) Preparation of porous layer: Ball-mill and mix 170 g of ZrOCl₂·8H₂O, 10 g of Y(NO₃)₃·6H₂O and 20 g of Si(NH)₂ precursor in a mass ratio of 85:5:10, add 1 g of polyvinylpyrrolidone PVP as a pore template agent, and prepare a green body with alternating dense and porous layers through a multi-channel extrusion device, controlling the interlayer angle at 45° ± 5°; (4)Prepare a laminated green body by multi-channel tape casting of the prepared matrix material, dense layer, and porous layer; (5)Reaction sintering: In the first stage, pre-sinter at 850 - 900 °C for 2 h in a nitrogen atmosphere to generate Si₃N₄ whiskers, and a solid-phase reaction of Al₂O₃ and ZrO₂ surface defects to form a transition layer. In the second stage, perform microwave sintering at 1250 °C, apply an axial pressure of 5 MPa, and keep the temperature for 30 min to generate alumina whiskers, Si₃N₄ whiskers, and a solid-phase reaction of ZrO₂ surface defects to form Zr 2- β-Si₃N₄ eutectic layer. In the third stage, introduce argon gas for cooling in the later stage of sintering. Example 2

[0019] A high-toughness stabilized zirconia ceramic is obtained by the following preparation method: (1)Preparation of matrix material: Add 2537 g of ZrOCl₂·8H₂O and 26 g of YCl₃ to 20 L of water to dissolve them completely. While stirring, dropwise add a mixed solution of ammonia water and hydrogen peroxide, adjust the pH of the solution to about 6, add 30 L of absolute ethanol to the reaction system, control the final pH to about 10, stir and react for about 90 min, let it stand for precipitation, wash with absolute ethanol and acetone, and calcine at 600 °C to obtain 3 mol% Y₂O₃-ZrO₂ nanopowder as the product; (2) Preparation of the dense layer: Take 735 ml of 0.2 mol / L Al(NO3)3 solution, add 1100 ml of absolute ethanol and 50 g of PEG, stir, add 485 g of Y2O3-ZrO2 nanoflour into the solution, stir and disperse ultrasonically to form a suspension, add ammonia water until the pH reaches 8.5, filter, wash, dry, and perform tape casting; (3) Preparation of the porous layer: Ball-mill and mix 850 g of ZrOCl2·8H2O, 50 g of Y(NO3)3·6H2O and 100 g of Si(NH)2 precursor in a mass ratio of 85:5:10, add 1 g of polyvinylpyrrolidone PVP as a pore template agent, and prepare a green body with alternating dense and porous layers through a multi-channel extrusion device, controlling the interlayer angle at 45° ± 5°; (4) Prepare a laminated green body by multi-channel tape casting of the prepared matrix material, dense layer, and porous layer; (5) Reaction sintering: In the first stage, pre-sinter at 850 - 900 °C for 2 h in a nitrogen atmosphere to generate Si3N4 whiskers, and a solid-phase reaction between Al2O3 and the surface defects of ZrO2 to form a transition layer. In the second stage, perform microwave sintering at 1250 °C, apply an axial pressure of 5 MPa, and keep the temperature for 30 min to generate alumina whiskers, a solid-phase reaction between Si3N4 whiskers and the surface defects of ZrO2 to form a ZrO 2- β-Si3N4 eutectic layer. In the third stage, introduce argon gas for cooling in the later stage of sintering. Comparative Example 1

[0020] A high-toughness stabilized zirconia ceramic is obtained by the following preparation method: Preparation of the matrix material: Add 507.4 g of ZrOCl2·8H2O and 5.2 g of YCl3 into 4 L of water to dissolve clearly, dropwise add a mixed solution of ammonia water and hydrogen peroxide under stirring, adjust the pH of the solution to about 6, add 6 L of absolute ethanol to the reaction system, control the end-point pH to about 10, stir and react for about 90 min, let it stand for precipitation, wash with absolute ethanol and acetone, and calcine at 600 °C to obtain a product of 3 mol% Y2O3-ZrO2 nanoflour; Add 3 g of Al2O3 and 97 g of matrix powder into 200 ml of absolute ethanol, ball-mill in a ball mill for 10 h for uniform dispersion, filter, wash, and dry; Prepare a laminated green body by multi-channel tape casting of the powder prepared in step (2); Reaction sintering: In the first stage, pre-sinter at 850 - 900 °C for 2 h in a nitrogen atmosphere for a solid-phase reaction between Al2O3 and the surface defects of ZrO2 to form a transition layer. In the second stage, perform microwave sintering at 1250 °C, apply an axial pressure of 5 MPa, and keep the temperature for 30 min. In the third stage, introduce argon gas for cooling in the later stage of sintering. Comparative Example 2

[0021] A high-toughness stabilized zirconia ceramic is obtained by the following preparation method: (1) Preparation of matrix material: Add 507.4 g of ZrOCl₂·8H₂O and 5.2 g of YCl₃ into 4 L of water to dissolve them completely. While stirring, dropwise add a mixed solution of ammonia water and hydrogen peroxide, adjust the pH of the solution to about 6, add 6 L of absolute ethanol to the reaction system, control the final pH to about 10, stir and react for about 90 min, let it stand for precipitation, wash with absolute ethanol and acetone, and calcine at 600 °C to obtain 3 mol% Y₂O₃-ZrO₂ nanometer powder as the product; (2) Preparation of porous layer: Ball-mill and mix 170 g of ZrOCl₂·8H₂O, 10 g of Y(NO₃)₃·6H₂O and 20 g of Si(NH)₂ precursor in a mass ratio of 85:5:10, add 1 g of polyvinylpyrrolidone PVP as a pore template agent, and prepare a green body with alternating dense and porous layers through a multi-channel extrusion device, controlling the interlayer angle at 45°±5°; (3) Prepare a layered green body by multi-channel tape casting of the prepared matrix material and porous layer; (4) Reaction sintering: In the first stage, pre-sinter at 850 - 900 °C for 2 h in a nitrogen atmosphere to generate Si₃N₄ whiskers. In the second stage, perform microwave sintering at 1250 °C, apply an axial pressure of 5 MPa, keep the temperature for 30 min, and a solid-phase reaction between the Si₃N₄ whiskers and the surface defects of ZrO₂ generates a ZrO 2- β-Si₃N₄ eutectic layer. In the third stage, introduce argon gas for cooling in the later stage of sintering. Comparative Example 3

[0022] A high-toughness stabilized zirconia ceramic is obtained by the following preparation method: (1) Preparation of matrix material: Add 507.4 g of ZrOCl₂·8H₂O and 5.2 g of YCl₃ into 4 L of water to dissolve them completely. While stirring, dropwise add a mixed solution of ammonia water and hydrogen peroxide, adjust the pH of the solution to about 6, add 6 L of absolute ethanol to the reaction system, control the final pH to about 10, stir and react for about 90 min, let it stand for precipitation, wash with absolute ethanol and acetone, and calcine at 600 °C to obtain 3 mol% Y₂O₃-ZrO₂ nanometer powder as the product; (2) Preparation of dense layer: Take 147 ml of 0.2 mol / L Al(NO₃)₃ solution, add 220 ml of absolute ethanol and 10 g of PEG and stir. Add 97 g of Y₂O₃-ZrO₂ nanometer powder into the solution, stir and disperse it ultrasonically to form a suspension, dropwise add ammonia water until the pH reaches 8.5, filter, wash, dry, and perform tape casting; (3) Preparation of porous layer: 170 g of ZrOCl2·8H2O, 10 g of Y(NO3)3·6H2O and 20 g of Si(NH)2 precursor were ball-milled and mixed according to a mass ratio of 85:5:10. 1 g of polyvinylpyrrolidone PVP was added as a pore template agent, and a green body with alternating dense and porous layers was prepared through a multi-channel extrusion device, with the interlayer angle controlled at 45° ± 5°; (4) The prepared matrix material, dense layer and porous layer were used to prepare a laminated green body through multi-channel tape casting; (5) Reaction sintering: At 1450 °C, under a pressure of 5 MPa, nitrogen was introduced, and the sample was sintered for 3 h while maintaining the temperature, and then cooled by introducing argon. Performance testing method

[0023] (1) The fracture toughness test standards are ASTM C1421 and ISO 23146; (2) The flexural strength test standards are ASTM C1161 and ISO 14704; (3) The hardness test standard is ASTM C1327 (Vickers hardness).

[0024] Performance Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 <![CDATA[Fracture toughness MPa∙m 1 / 2 > 16.3 16.5 7.5 9.3 15.8 Flexural strength MPa 1380 1350 950 1020 1200 Sintering temperature °C 1250 1250 1250 1250 1450 Vickers hardness GPa 14.8 15.0 12.5 13.2 14.1 The results show that the high-toughness zirconia ceramic provided by the present invention effectively improves its fracture toughness and flexural strength, reduces the sintering temperature and saves energy consumption. It can be seen from Examples 1-2 and Comparative Examples 1-3 that: (1) Gradient-distributed submicron alumina is introduced into the matrix, and whiskers are generated through sintering to form a "whisker-nanoparticle-matrix" three-stage toughening network, effectively improving its fracture toughness and flexural strength; (2) The porous layer sintering produces β-Si3N4 whiskers in-situ, and the interface transition zone is a ZrO2-β-Si3N4 eutectic layer, further improving the fracture toughness and flexural strength; (3) The sintering temperature is reduced, energy consumption is saved, and the performance of the material is improved.

[0025] The above embodiments only represent several implementation manners of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent should be subject to the appended claims.

Claims

1. A stabilized zirconia high-toughness ceramic, characterized in that, It includes a matrix material, a reinforcing phase, and an interfacial transition zone; The matrix material is Y2O3-ZrO2 nanopowder with a particle size of 20-100 nm; The reinforcing phase includes alternately distributed dense layers and porous layers; The dense layer is formed by alumina whiskers radially distributed along the radial direction, forming a "whisker-nanoparticle-matrix" three-stage toughening network; The porous layer contains in-situ generated β-Si3N4 whiskers; the porous layer includes ZrOCl2·8H2O, Y(NO3)3·6H2O, Si(NH)2, and a pore template agent polyvinylpyrrolidone PVP; the interlayer angle of the porous layer is controlled at 45±5°; The interfacial transition zone is a ZrO2-β-Si3N4 eutectic layer.

2. A stabilized zirconia high-toughness ceramic according to claim 1, characterized in that, Preparation method of the matrix material: Prepare a mixed solution of ZrOCl2·8H2O and YCl3 according to the proportion that the mass fraction of yttrium oxide is 3%. While stirring, drop a mixed solution of ammonia water and hydrogen peroxide into the solution, adjust the pH of the solution to about 6, add absolute ethanol to the reaction system, control the end-point pH to about 10, react for about 90 min, let it stand for precipitation, wash with absolute ethanol and acetone, and calcine at 600 °C to obtain the product 3mol%Y2O3-ZrO2 nanopowder.

3. A stabilized zirconia high-toughness ceramic according to claim 1, characterized in that Preparation of the dense layer: Prepare a 0.2mol / L Al(NO3)3 solution according to the proportion that the mass fraction of Al2O3 is 3%, add absolute ethanol and PEG, add Y2O3-ZrO2 nanopowder into the solution and stir and ultrasonically disperse to form a suspension, drop ammonia water until the pH is 8.5, filter, wash, dry, tape-cast, and calcine at 1250 °C to obtain the dense layer.

4. A stabilized zirconia high-toughness ceramic according to claim 1, characterized in that, Preparation of the porous layer: Ball-mill and mix the ZrOCl2·8H2O, Y(NO3)3·6H2O and Si(NH)2 precursors in a mass ratio of 85:5:10, add 0.5wt% polyvinylpyrrolidone PVP as a pore template agent, prepare a green body with alternately dense and porous layers through a multi-channel extrusion device, and generate β-Si3N4 whiskers in a nitrogen atmosphere at 850-900 °C for 2 h of pre-calcination.

5. A stabilized zirconia high-toughness ceramic according to claim 1, characterized in that, Introduce gradient-distributed submicron alumina whiskers with a diameter of 0.2-0.5 μm and an aspect ratio of 10-15 into the dense layer.

6. A stabilized zirconia high-toughness ceramic according to claim 1, characterized in that, The in-situ generated β-Si3N4 whiskers in the porous layer have an aspect ratio ≥20, the thickness ratio of the dense layer to the porous layer is 1:(0.8-1.2), and the porosity of the porous layer is 15-20%.

7. A method for preparing a stabilized zirconia high-toughness ceramic according to any one of claims 1 to 6, characterized in that, It includes the following steps: S1. Prepare a layered green body by tape-casting the prepared matrix material, dense layer, and porous layer through a multi-channel tape-casting process; S2. Reaction sintering: In the first stage, β-Si3N4 whiskers are formed by pre-sintering at 850 - 900 °C for 2 h in a nitrogen atmosphere, and a transition layer is formed by the solid-phase reaction of surface defects of Al2O3 and ZrO2. In the second stage, microwave sintering is carried out at 1250 °C, an axial pressure of 5 MPa is applied, and the temperature is kept for 30 min to form alumina whiskers. The solid-phase reaction of β-Si3N4 whiskers and surface defects of ZrO2 generates a ZrO 2- β-Si3N4 eutectic layer. In the third stage, argon gas is introduced for cooling in the later stage of sintering.

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