A kind of stabilized zirconia high-toughness ceramic and its preparation method

Abstract

The present invention discloses a kind of stable zirconia high-toughness ceramic and its preparation method, including matrix material, reinforcement phase, interface transition zone, matrix material is Y2O3-ZrO2 nanopowder, reinforcement phase comprises alternating dense layer and porous layer, dense layer makes alumina whiskers radially distributed in radial direction, forms "whisker-nanoparticle-matrix" three-level toughening network, porous layer contains in-situ generated β-Si3N4 whiskers, interface transition zone is ZrO2-β-Si3N4 eutectic layer. In the present invention, whiskers are added, fracture energy is consumed by pull-out effect, nanoparticles suppress crack propagation by pinning effect, matrix phase transformation toughening, improve the fracture toughness of ceramics, crack propagation path is extended 3~5 times. On the other hand, sintering temperature is reduced to reduce energy consumption.

Description

Technical Field

[0001] The present 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 are widely used because of 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 to toughen them. For example, Chinese patent CN021111464 discloses a Mg-stabilized TZP ceramic. This ceramic can achieve a partial toughening effect by doping with Mg, but this effect is not obvious. Moreover, the strength of the ceramic samples prepared according to this method is relatively low, only about 590 MPa, 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 require reactions 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, cracking of the porcelain body, 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 has a strength of up to 1200 MPa, its toughness is relatively low. Summary of the Invention

[0005] Purpose of the Invention: This invention provides a high-toughness stabilized zirconia ceramic and its preparation method. The invention incorporates whiskers, which dissipate fracture energy through a pullout effect. Nanoparticles inhibit crack propagation through a pinning effect, and the matrix undergoes phase transformation toughening, resulting in improved fracture toughness and a 3-5-fold increase in crack propagation path. Furthermore, the sintering temperature is lowered, thereby reducing energy consumption.

[0006] Technical solution: A stabilized zirconia high-toughness ceramic, including a matrix material, a reinforcement phase, and an interface transition zone;

[0007] Among them, the matrix material is Y2O3-ZrO2 nanopowder with a particle size of 20~100nm;

[0008] The reinforcement phase consists of alternating dense and porous layers, e.g. Figure 2 As shown;

[0009] The dense layer is composed of alumina whiskers distributed radially, forming a three-level toughening network of "whiskers-nanoparticles-matrix";

[0010] The porous layer contains in-situ generated β-Si3N4 whiskers, including ZrOCl2·8H2O, Y(NO3)3·6H2O, Si(NH)2, and pore template pores, and the interlayer angle is controlled at 45°±5° through a multi-channel extrusion device;

[0011] The interface transition zone is ZrO 2- β-Si3N4 eutectic layer.

[0012] Preferably, the matrix material preparation method is as follows: ZrOCl2·8H2O and YCl3 are prepared into a mixed solution in a ratio of 3% of yttrium oxide mass fraction, a mixed solution of ammonia and hydrogen peroxide is added dropwise to the solution under stirring, the pH of the solution is adjusted to about 6, anhydrous ethanol is added to the reaction system, the end point pH is controlled to about 10, the reaction is carried out for about 90 minutes, the mixture is allowed to stand and precipitate, the mixture is washed with anhydrous ethanol and acetone, and the mixture is calcined at 600°C to obtain the product 3 mol% Y2O3-ZrO2 nanopowder.

[0013] Preferably, the dense layer is prepared by preparing a 0.2 mol / L Al(NO3)3 solution with an Al2O3 mass fraction of 3%, adding anhydrous ethanol and PEG, adding Y2O3-ZrO2 nanopowder to the solution, stirring and ultrasonically dispersing to form a suspension, adding ammonia water to pH 8.5, filtering, washing, drying, casting, and calcining at 1250°C to obtain a dense layer.

[0014] Preferably, the porous layer is prepared by ball milling ZrOCl2·8H2O, Y(NO3)3·6H2O and Si(NH)2 precursors in a mass ratio of 85:5:10, adding 0.5wt% polyvinylpyrrolidone PVP as a pore template, and preparing a green body with alternating dense porous layers through a multi-channel extrusion device, and pre-calcining at 850-900℃ for 2h in a nitrogen atmosphere to generate Si3N4 whiskers.

[0015] Preferably, gradient-distributed submicron aluminum oxide whiskers with a diameter of 0.2-0.5 μm and an aspect ratio of 10-15 are introduced into the dense layer.

[0016] Preferably, the aspect ratio of the in-situ generated β-Si3N whiskers in the porous layer is ≥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%.

[0017] A method for preparing stabilized zirconia high-toughness ceramics comprises the following steps:

[0018] S1, preparing a layered green body by multi-channel tape casting of the prepared base material, dense layer, and porous layer;

[0019] S2, reaction sintering: In the first stage, Si3N4 whiskers are generated in a nitrogen atmosphere at 850-900℃ for 2h, and Al2O3 reacts with ZrO2 surface defects to form a transition layer. In the second stage, microwave sintering is performed at 1250℃, with an axial pressure of 5MPa and heat preservation for 30min to generate alumina whiskers, Si3N4 whiskers react with ZrO2 surface defects to form ZrO2 2- β-Si3N4 eutectic layer, the third stage is to introduce argon gas cooling in the late sintering stage. Beneficial effects

[0020] The present invention prepares Y2O3-ZrO2 nanopowder and introduces gradient-distributed submicron alumina whiskers into a dense layer, so that the alumina whiskers are radially distributed along the radial direction, forming a three-level toughening network of "whiskers-nanoparticles-matrix". The whiskers consume fracture energy through the pull-out effect, the nanoparticles inhibit crack propagation through the pinning effect, and the matrix undergoes phase transformation toughening (t→m phase transformation). The fracture toughness and bending strength are significantly enhanced compared to conventional 3Y-TZP. The ceramic material of the present invention can be applied to cutting tools, molds, wear-resistant parts, engine components, etc., which can effectively improve the performance of the material.

[0021] The porous layer of the present invention contains in-situ generated β-Si3N4 whiskers, 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 bending strength. The ceramic material of the present invention can be applied to cutting tools, molds, wear-resistant parts, armor, etc., which can greatly improve its fracture toughness.

[0022] The present invention adopts low-temperature reaction sintering, which reduces the sintering temperature by 150-200°C compared with the traditional sintering temperature, thereby reducing production energy consumption. By adopting this sintering method, the bending strength of the ceramic material is enhanced. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is the SEM image of alumina whiskers;

[0024] Figure 2 Schematic diagram of the alternating structure of dense layer and porous layer;

[0025] Figure 3This is the SEM image of the interface transition zone. DETAILED DESCRIPTION

[0026] In order to make the technical solution of the present invention clearer, the present invention is further described in detail below with reference to specific embodiments. Example 1

[0027] A stabilized zirconia high-toughness ceramic is obtained by the following preparation method:

[0028] (1) Preparation of matrix material: 507.4 g ZrOCl2·8H2O and 5.2 g YCl3 were added to 4 L of water, and a mixed solution of ammonia and hydrogen peroxide was added dropwise under stirring to adjust the pH of the solution to about 6. 6 L of anhydrous ethanol was added to the reaction system to control the end point pH to about 10. The reaction was stirred for about 90 min, and the mixture was allowed to stand for precipitation. The mixture was washed with anhydrous ethanol and acetone, and calcined at 600 °C to obtain the product 3 mol% Y2O3-ZrO2 nanopowder.

[0029] (2) Preparation of dense layer: Take 147 ml of 0.2 mol / L Al(NO3)3 solution, add 220 ml of anhydrous ethanol and 10 g of PEG, and stir. Add 97 g of Y2O3-ZrO2 nanopowder to the solution, stir and disperse by ultrasonic to form a suspension, add ammonia water dropwise to pH 8.5, filter, wash, dry, and cast;

[0030] (3) Preparation of porous layer: 170 g ZrOCl2·8H2O, 10 g Y(NO3)3·6H2O and 20 g Si(NH)2 precursor were ball-milled at a mass ratio of 85:5:10, and 1 g polyvinylpyrrolidone (PVP) was added as a pore template. A green body with alternating dense porous layers was prepared by a multi-channel extrusion device, with the interlayer angle controlled at 45°±5°.

[0031] (4) preparing a layered green body by multi-channel tape casting of the prepared matrix material, dense layer, and porous layer;

[0032] (5) Reaction sintering: In the first stage, Si3N4 whiskers are generated in a nitrogen atmosphere at 850-900℃ for 2h, and Al2O3 reacts with ZrO2 surface defects to form a transition layer. In the second stage, microwave sintering is performed at 1250℃, with an axial pressure of 5MPa and heat preservation for 30min to generate alumina whiskers, Si3N4 whiskers and ZrO2 surface defects to form ZrO2 solid phase reaction. 2- β-Si3N4 eutectic layer, the third stage is to introduce argon gas cooling in the late sintering stage. Example 2

[0033] A stabilized zirconia high-toughness ceramic is obtained by the following preparation method:

[0034] (1) Preparation of matrix material: 2537g ZrOCl2·8H2O and 26g YCl3 were added to 20L of water solution, and a mixed solution of ammonia and hydrogen peroxide was added dropwise under stirring to adjust the pH of the solution to about 6. 30L of anhydrous ethanol was added to the reaction system to control the end point pH to about 10. The reaction was stirred for about 90min, and the mixture was allowed to stand for precipitation. The mixture was washed with anhydrous ethanol and acetone, and calcined at 600℃ to obtain the product 3mol% Y2O3-ZrO2 nanopowder.

[0035] (2) Preparation of dense layer: Take 735 ml of 0.2 mol / L Al(NO3)3 solution, add 1100 ml of anhydrous ethanol and 50 g of PEG and stir, add 485 g of Y2O3-ZrO2 nanopowder to the solution, stir and disperse by ultrasonic to form a suspension, add ammonia water dropwise to pH 8.5, filter, wash, dry, and cast;

[0036] (3) Preparation of porous layer: 850 g ZrOCl2·8H2O, 50 g Y(NO3)3·6H2O and 100 g Si(NH)2 precursor were ball-milled at a mass ratio of 85:5:10, and 1 g polyvinylpyrrolidone (PVP) was added as a pore template. A green body with alternating dense porous layers was prepared by a multi-channel extrusion device, with the interlayer angle controlled at 45°±5°.

[0037] (4) preparing a layered green body by multi-channel tape casting of the prepared matrix material, dense layer, and porous layer;

[0038] (5) Reaction sintering: In the first stage, Si3N4 whiskers are generated in a nitrogen atmosphere at 850-900℃ for 2h, and Al2O3 reacts with ZrO2 surface defects to form a transition layer. In the second stage, microwave sintering is performed at 1250℃, with an axial pressure of 5MPa and heat preservation for 30min to generate alumina whiskers, Si3N4 whiskers and ZrO2 surface defects to form ZrO2 solid phase reaction. 2- β-Si3N4 eutectic layer, the third stage is to introduce argon gas cooling in the late sintering stage. Comparative Example 1

[0039] A stabilized zirconia high-toughness ceramic is obtained by the following preparation method:

[0040] Preparation of matrix material: 507.4g ZrOCl2·8H2O and 5.2g YCl3 were added to 4L of water, and a mixed solution of ammonia and hydrogen peroxide was added dropwise with stirring to adjust the pH of the solution to about 6. 6L of anhydrous ethanol was added to the reaction system to control the end point pH to about 10. The reaction was stirred for about 90min, and the mixture was allowed to settle. The mixture was washed with anhydrous ethanol and acetone, and calcined at 600℃ to obtain the product 3mol% Y2O3-ZrO2 nanopowder.

[0041] 3g Al2O3 and 97g matrix powder were added to 200ml of anhydrous ethanol and milled in a ball mill for 10h until uniformly dispersed, filtered, washed and dried;

[0042] The powder prepared in step (2) is subjected to multi-channel tape casting to prepare a layered green body;

[0043] Reaction sintering: In the first stage, pre-sintering at 850-900℃ for 2h in nitrogen atmosphere causes solid phase reaction between Al2O3 and ZrO2 surface defects to form a transition layer. In the second stage, microwave sintering is performed at 1250℃, applying an axial pressure of 5MPa and keeping warm for 30min. In the third stage, argon gas is introduced for cooling in the late stage of sintering. Comparative Example 2

[0044] A stabilized zirconia high-toughness ceramic is obtained by the following preparation method:

[0045] (1) Preparation of matrix material: 507.4 g ZrOCl2·8H2O and 5.2 g YCl3 were added to 4 L of water, and a mixed solution of ammonia and hydrogen peroxide was added dropwise under stirring to adjust the pH of the solution to about 6. 6 L of anhydrous ethanol was added to the reaction system to control the end point pH to about 10. The reaction was stirred for about 90 min, and the mixture was allowed to stand for precipitation. The mixture was washed with anhydrous ethanol and acetone, and calcined at 600 °C to obtain the product 3 mol% Y2O3-ZrO2 nanopowder.

[0046] (2) Preparation of porous layer: 170 g ZrOCl2·8H2O, 10 g Y(NO3)3·6H2O and 20 g Si(NH)2 precursor were ball-milled at a mass ratio of 85:5:10, and 1 g polyvinylpyrrolidone (PVP) was added as a pore template. A green body with alternating dense porous layers was prepared by a multi-channel extrusion device, with the interlayer angle controlled at 45°±5°.

[0047] (3) preparing a layered green body by multi-channel tape casting of the prepared base material and porous layer;

[0048] (4) Reaction sintering: In the first stage, Si3N4 whiskers are generated by pre-sintering at 850-900℃ for 2h in nitrogen atmosphere. In the second stage, Si3N4 whiskers are sintered by microwave at 1250℃, with an axial pressure of 5MPa and heat preservation for 30min. The solid phase reaction between Si3N4 whiskers and ZrO2 surface defects generates ZrO 2- β-Si3N4 eutectic layer, the third stage is to introduce argon gas cooling in the late sintering stage. Comparative Example 3

[0049] A stabilized zirconia high-toughness ceramic is obtained by the following preparation method:

[0050] (1) Preparation of matrix material: 507.4 g ZrOCl2·8H2O and 5.2 g YCl3 were added to 4 L of water, and a mixed solution of ammonia and hydrogen peroxide was added dropwise under stirring to adjust the pH of the solution to about 6. 6 L of anhydrous ethanol was added to the reaction system to control the end point pH to about 10. The reaction was stirred for about 90 min, and the mixture was allowed to stand for precipitation. The mixture was washed with anhydrous ethanol and acetone, and calcined at 600 °C to obtain the product 3 mol% Y2O3-ZrO2 nanopowder.

[0051] (2) Preparation of dense layer: Take 147 ml of 0.2 mol / L Al(NO3)3 solution, add 220 ml of anhydrous ethanol and 10 g of PEG, and stir. Add 97 g of Y2O3-ZrO2 nanopowder to the solution, stir and disperse by ultrasonic to form a suspension, add ammonia water dropwise to pH 8.5, filter, wash, dry, and cast;

[0052] (3) Preparation of porous layer: 170 g ZrOCl2·8H2O, 10 g Y(NO3)3·6H2O and 20 g Si(NH)2 precursor were ball-milled at a mass ratio of 85:5:10, and 1 g polyvinylpyrrolidone (PVP) was added as a pore template. A green body with alternating dense porous layers was prepared by a multi-channel extrusion device, with the interlayer angle controlled at 45°±5°.

[0053] (4) preparing a layered green body by multi-channel tape casting of the prepared matrix material, dense layer, and porous layer;

[0054] (5) Reaction sintering: at 1450℃, pressure 5MPa, introduce nitrogen, keep warm and sinter for 3h, introduce argon to cool down.

[0055] Performance testing methods

[0056] (1) Fracture toughness test standards ASTM C1421 and ISO 23146;

[0057] (2) Flexural strength test standards ASTM C1161 and ISO 14704;

[0058] (3) Hardness test standard ASTM C1327 (Vickers hardness).

[0059] The performance test comparison results of the above embodiments and comparative examples are shown in the following table:

[0060] 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 Bending strength MPa 1380 1350 950 1020 1200 Sintering temperature ℃ 1250 1250 1250 1250 1450 Vickers hardness GPa 14.8 15.0 12.5 13.2 14.1

[0061] The results show that the stabilized zirconia high-toughness ceramic provided by the present invention effectively improves its fracture toughness and flexural strength, reduces sintering temperature, and saves energy. It can be seen from Examples 1-2 and Comparative Examples 1-3 that (1) the introduction of gradient-distributed submicron-sized alumina into the dense layer produces whiskers through sintering, forming a three-level toughening network of "whiskers-nanoparticles-matrix", which effectively improves its fracture toughness and flexural strength; (2) the porous layer is sintered to produce in-situ generated β-Si3N4 whiskers, and the interface transition zone is a ZrO2-β-Si3N4 eutectic layer, which further improves the fracture toughness and flexural strength; (3) the sintering temperature is reduced, energy consumption is saved, and the performance of the material is improved.

[0062] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A stabilized zirconia high-toughness ceramic, characterized in that: Including matrix material, reinforcement phase, and interface transition zone; The matrix material is Y2O3-ZrO2 nanopowder with a particle size of 20-100 nm. The matrix material preparation method comprises the following steps: preparing a mixed solution of ZrOCl2·8H2O and YCl3 in a ratio of 3% by mass of yttrium oxide; adding a mixed solution of ammonia and hydrogen peroxide dropwise to the solution under stirring; adjusting the pH of the solution to 6; adding anhydrous ethanol to the reaction system to control the end point pH to 10; reacting for 90 minutes; standing to precipitate; washing with anhydrous ethanol and acetone; and calcining at 600°C to obtain a product of 3 mol% Y2O3-ZrO2 nanopowder; The reinforcement phase comprises alternating dense layers and porous layers; The dense layer is composed of alumina whiskers distributed radially, forming a three-level toughening network of "whiskers-nanoparticles-matrix". The dense layer is prepared by preparing a 0.2 mol / L Al(NO3)3 solution with an Al2O3 mass fraction of 3%, adding anhydrous ethanol and PEG, adding Y2O3-ZrO2 nanopowder to the solution, stirring and ultrasonically dispersing to form a suspension, adding ammonia water dropwise to a pH of 8.5, filtering, washing, and drying. The porous layer contains in-situ generated β-Si3N4 whiskers; the raw materials of the porous layer are ZrOCl2·8H2O, Y(NO3)3·6H2O, Si(NH)2 and pore template agent polyvinyl pyrrolidone (PVP); the interlayer angle of the porous layer is controlled to be 45±5°; the porous layer is prepared by ball milling ZrOCl2·8H2O, Y(NO3)3·6H2O and Si(NH)2 precursors in a mass ratio of 85:5:10, adding 0.5wt% polyvinyl pyrrolidone (PVP) as a pore template, and preparing a green body through a multi-channel extrusion device; The interface transition zone is a ZrO2-β-Si3N4 eutectic layer; The preparation method of the stabilized zirconia high-toughness ceramic is as follows: S1, preparing a layered green body by multi-channel tape casting of the prepared base material, dense layer, and porous layer; S2, reaction sintering: In the first stage, sintering was performed at 850-900℃ for 2h in nitrogen atmosphere to generate β-Si3N4 whiskers, solid phase reaction of Al2O3 and ZrO2 surface defects to generate transition layer, and in the second stage, microwave sintering was performed at 1250℃, axial pressure of 5MPa was applied, and heat preservation was performed for 30min to generate aluminum oxide whiskers, solid phase reaction of β-Si3N4 whiskers and ZrO2 surface defects to generate ZrO 2- β-Si3N4 eutectic layer, the third stage is to introduce argon gas cooling in the late sintering stage.

2. The stabilized zirconia high-toughness ceramic according to claim 1, characterized in that: Gradiently distributed submicron aluminum oxide whiskers with a diameter of 0.2-0.5 μm and an aspect ratio of 10-15 are introduced into the dense layer.

3. The stabilized zirconia high-toughness ceramic according to claim 1, characterized in that: The aspect ratio of the in-situ generated β-Si3N4 whiskers in the porous layer is ≥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%.

Images