A high-strength structural ceramic and its preparation method

Abstract

The present application relates to the technical field of ceramic materials, specifically disclosing a high-strength structural ceramic and its preparation method. The high-strength structural ceramic comprises the following raw materials in parts by weight: 30-38 parts alumina ore powder and 46-56 parts zirconium oxide powder; the preparation method comprises: mixing the zirconium oxide powder with 10-18 parts starch, and then mixing with alumina ore powder to prepare a mixture; cold isostatically pressing the prepared mixture and calcining it to obtain the high-strength structural ceramic. The high-strength structural ceramic of the present application can be used in fields such as ceramic cutting tools and ceramic bearings, and has the advantage of reducing the adverse effects of external forces on the service life of the resulting ceramic components.

Description

Technical Field

[0001] The present application relates to the technical field of ceramic materials, and more particularly, to a high-strength structural ceramic and a preparation method thereof. Background Art

[0002] Structural ceramics, as a branch of ceramic materials, have mechanical, thermal, and chemical properties such as high temperature resistance, erosion resistance, corrosion resistance, high hardness, high strength, and low creep rate. They can adapt to harsh environments or engineering application conditions, and are therefore often used to manufacture various structural components.

[0003] Currently, common structural ceramics can be roughly divided into four categories, namely alumina structural ceramics, zirconia structural ceramics, silicon carbide structural ceramics, and boron nitride and boron carbide structural ceramics. Among them, alumina structural ceramics, as a kind of high-strength structural ceramics, usually refers to structural ceramics sintered with alumina as the main material. It has high hardness, super wear resistance, strong high temperature resistance, certain impact resistance and corrosion resistance, and can be used as refractory materials, wear-resistant materials, such as crucibles, high-temperature furnace tubes, etc., and can also be used to manufacture corundum ball grinding machines, ceramic ball valves, sand making machine dividing cones, etc. It has a long service life and a low price, so it is widely used.

[0004] In the related art, high-strength structural ceramics are produced using alumina as the main component to meet the strength requirements of structural ceramics during use. However, in actual use, alumina structural ceramics are easily worn or broken under the action of impact or pressure, which can easily affect the service life of the produced ceramic components. Summary of the Invention

[0005] In order to reduce the adverse effects of external forces on the service life of the manufactured ceramic components, the present application provides a high-strength structural ceramic and a preparation method thereof.

[0006] In a first aspect, the present application provides a high-strength structural ceramic, which adopts the following technical solution:

[0007] A high-strength structural ceramic comprises the following raw materials in parts by weight: 30-38 parts of aluminum oxide powder and 46-56 parts of zirconium oxide powder.

[0008] By adopting the above technical solution, zirconium oxide powder is mixed with alumina ore powder. At this time, part of the zirconium oxide powder fills the pores of the alumina ore powder, and the other part of the zirconium oxide powder adheres to the surface of the alumina ore powder, thereby supporting the alumina ore powder and reducing the shrinkage of the alumina ore powder at high temperature, thereby reducing the possibility of brittleness of the high-strength structural ceramics produced.

[0009] Preferably, the zirconium oxide powder is a stabilized zirconium oxide powder, which is prepared from magnesium chloride and zirconium oxychloride in a weight ratio of (1-2):100.

[0010] By adopting the above technical solution, when using stable zirconia powder to fill the pores of alumina ore powder, the possibility of zirconia powder shrinking due to crystal transformation at high temperature is avoided as much as possible, thereby improving the stability of zirconia powder filling and supporting the pores of alumina ore powder.

[0011] Preferably, the D50 particle size of the stabilized zirconia powder is 45±5 nm.

[0012] By adopting the above technical solution, the 40-50nm stabilized zirconia powder has high stability, and experiments have shown that zirconia with this particle size can more fully fill the surface pores of the alumina ore powder. Zirconia with smaller particle sizes is more likely to agglomerate into large particles, resulting in poor filling properties, or requiring too much dispersant. However, too much dispersant will ultimately lead to too little zirconia being filled into the alumina during the calcination process. Although the agglomeration of zirconia with larger particles is reduced, the pore size may be relatively large relative to the surface of the alumina ore powder, and the filling rate is not ideal. Therefore, when preparing high-strength structural ceramics, the combination of stabilized zirconia and starch is more stable, the water washability and wear resistance are improved, and the forming is easy.

[0013] Preferably, the D50 particle size of the alumina ore powder is 10-90 μm, and the total pore volume of the pores with a pore size of less than 2 μm in the alumina ore powder is 0.11-0.29 cm 3 / g.

[0014] In a second aspect, the present application provides a method for preparing high-strength structural ceramics, using the following technical solution:

[0015] A method for preparing high-strength structural ceramics comprises the following steps:

[0016] The zirconium oxide powder is mixed with 10-18 parts of starch, and then mixed with aluminum oxide ore powder to prepare a mixture;

[0017] The prepared mixture is subjected to cold isostatic pressing and calcined to obtain high-strength structural ceramics.

[0018] Preferably, the starch is amylopectin.

[0019] By adopting the above technical solution and selecting amylopectin, during the mixing process, the stabilized zirconia powder adheres to each branch of the amylopectin. At this time, the starch connects the stabilized zirconia with the alumina mineral powder, making it easy to form high-strength structural ceramics. At the same time, it is easy to fill the stabilized zirconia into the pores of the alumina mineral powder, so that the alumina mineral powder shrinks under high-temperature calcination and is effectively supported by the zirconia powder.

[0020] Preferably, before mixing the zirconium oxide powder with starch, the zirconium oxide powder is first mixed with 0.5-1.5 parts of a dispersant to prepare a premix, and the dispersant is sodium hexametaphosphate.

[0021] By adopting the above technical solution, sodium hexametaphosphate disperses and stabilizes zirconium oxide, reducing the possibility of agglomeration of stabilized zirconium oxide powder, and sodium trimetaphosphate produced by the hydrolysis of sodium hexametaphosphate cross-links the starch. The cross-linked amylopectin shrinks at high temperature and draws more stabilized zirconium oxide powder into the pores of the alumina ore powder, thereby forming support for the alumina ore powder and reducing the possibility of shrinkage when the alumina ore powder undergoes a crystal phase transition.

[0022] Preferably, after the mixed material is prepared, 40±10 parts of water are added to the prepared mixed material, the temperature is raised to 40±10° C., the mixture is kept for 2±1 h, and then washed with water to prepare a washed material;

[0023] The prepared washed material is subjected to cold isostatic pressing and calcined to obtain high-strength structural ceramics.

[0024] By adopting the above technical solution, sodium hexametaphosphate is first coated on the surface of stable zirconium oxide powder, and then starch is coated on the surface of sodium hexametaphosphate. At this time, the stable zirconium oxide powder is attached to the side chains of the starch. When the sodium hexametaphosphate is hydrolyzed and the starch is cross-linked, the various side chains of the starch connect more stable zirconium oxide powder with the pores of the alumina mineral powder. During the high-temperature process, the cross-linked starch gradually shrinks and pulls the stable zirconium oxide into the pores of the alumina mineral powder, thereby filling the stable zirconium oxide powder in the pores of the alumina mineral powder, hindering the shrinkage of the alumina mineral powder at high temperature, and improving the fracture toughness.

[0025] In summary, this application has the following beneficial effects:

[0026] 1. Mix zirconia powder with alumina powder and use starch as a binder to improve the adhesion between particles and facilitate forming. At this time, part of the zirconia powder fills the pores of the alumina powder, and the other part of the zirconia powder adheres to the surface of the alumina powder, thereby supporting the alumina powder and reducing the shrinkage of the alumina powder at high temperature, thereby reducing the possibility of brittleness of the high-strength structural ceramics.

[0027] 2. Sodium hexametaphosphate disperses and stabilizes zirconium oxide, reducing the possibility of agglomeration of stabilized zirconium oxide powder. Sodium trimetaphosphate produced by the hydrolysis of sodium hexametaphosphate cross-links starch. The cross-linked amylopectin shrinks at high temperatures and pulls the stabilized zirconium oxide powder into the pores of the alumina ore powder, thereby forming support for the alumina ore powder and reducing the possibility of shrinkage when the alumina ore powder undergoes a crystal phase transition. DETAILED DESCRIPTION

[0028] The compression strength test method and the fracture toughness test method of all embodiments are as follows:

[0029] 1. Compression strength

[0030] The compressive strength of high-strength structural ceramics is tested according to the national standard GB / T 1964-1996 "Test method for compressive strength of porous ceramics".

[0031] Test method: Place a cube sample with a side length of 20±0.5mm in an oven, dry it at 110±5℃ for 2h, and then place it in a desiccator to cool to room temperature; measure the side length of the sample's pressure surface and calculate the area; place the sample in the center of the lower pressure plate of the material testing machine, apply a load at a rate of 2.5MPa / s until the sample is destroyed, and read the maximum load value when the sample is destroyed.

[0032] The testing environment is: 23℃.

[0033] 2. Fracture toughness

[0034] The fracture toughness of high-strength structural ceramics is tested according to the national standard GB / T 23806-2009 "Fine Ceramics Fracture Toughness Test Method Single Edge Precracked Beam (SEPB) Method".

[0035] Test method: A cuboid with a length of 36 mm and four long sides with chamfers of 45 ± 5 degrees and a length of 0.12 ± 0.03 mm was used as the specimen. The thickness and width of the specimen were measured, and the crack source was induced by the single-sided bevel incision method. The specific method is to use a wire saw to make a bevel incision in the middle of the length direction of the specimen, with the lower surface as the tensile surface;

[0036] The distance between the shallower end of the bevel cut and the tensile surface is 0.2 mm, and the distance between the deeper end of the bevel cut and the tensile surface is 1.2 mm (the specimen width is 4 mm). The width of the bevel cut is 0.2 mm. The specimen with the bevel cut is placed between the loading platform and the anvil of the pre-crack initiation device. The specimen, the anvil groove and the lower surface of the loading platform are cleaned with acetone. The specimen with the crack source is placed in the anvil groove, with the length direction of the specimen perpendicular to the center groove.

[0037] Place the loading platform on the specimen, symmetrically positioned between the loading platform and the anvil. Apply a vertical load at a rate of 300 N / s. Stop loading immediately upon hearing a slight "snap" sound. Remove the specimen and observe under an optical microscope to confirm a crack has been induced on the specimen surface. Dyeing solution mixed with acetone is dripped into the crack to stain it and locate the pre-crack tip. After the dye is completely dry, perform a four-point bending test.

[0038] Place the sample on a bending tester with the roller perpendicular to the length direction of the sample and a loading speed of 0.5 mm / min. Measure and calculate the fracture toughness value.

[0039] The testing environment is: 23℃.

[0040] The present application is further described in detail below with reference to the embodiments.

[0041] raw material

[0042] The raw materials for all experimental examples and embodiments of this application can be obtained commercially. Among them, the alumina ore powder is composed of 40%-76% γ-Al2O3 and 24%-60% α-Al2O3.

[0043] Preparation Example

[0044] Preparation Example 1

[0045] A stabilized zirconium oxide powder is prepared by the following steps:

[0046] 100 g of zirconium oxychloride was added to the alcohol solution and mixed to prepare a mixed solution;

[0047] 1 g of magnesium chloride and glycerol were added to the mixed solution, and the pH was adjusted to 2. The mixture was heated to 70° C. and mixed. Propylene oxide was added until the pH reached 7. The solid and liquid were separated to obtain a precursor.

[0048] The precursor was added into water and kept at 180°C for 7 hours. After solid-liquid separation, the mixture was dried, calcined and crushed to obtain stable zirconia powder.

[0049] Preparation Example 2

[0050] The difference from Preparation Example 1 is that 2 g of magnesium chloride was added in Preparation Example 2.

[0051] Preparation Example 3

[0052] The difference from Preparation Example 1 is that 3 g of magnesium chloride was added in Preparation Example 3.

[0053] Example

[0054] Example 1

[0055] Examples 1.11-1.13

[0056] Example 1.11

[0057] A high-strength structural ceramic is prepared by the following steps:

[0058] After 51g of zirconium oxide powder was mixed with 14g of pullulan, 34g of total pore volume of 0.26cm 3 / g of alumina ore powder (the D50 particle size of the pores with a pore size of less than 2 μm is 50 μm) to prepare a mixture;

[0059] The prepared mixture is subjected to cold isostatic pressing and calcined to obtain high-strength structural ceramics.

[0060] Example 1.12

[0061] The difference from Example 1.11 is that 10 g of amylopectin was added in Example 1.12.

[0062] Example 1.13

[0063] The difference from Example 1.11 is that 18 g of amylopectin was added in Example 1.13.

[0064] Examples 1.21-1.23

[0065] Different from Example 1.11, in Examples 1.21-1.23, an equal amount of amylose with the same molecular weight was used to replace amylopectin.

[0066] Comparative Example 1

[0067] Different from Example 1.11, no starch was added in Comparative Example 1.

[0068] The compressive strength and fracture toughness of the high-strength structural ceramics prepared in Examples 1.1-1.2 and Comparative Example 1 were tested. The test data are shown in Table 1.

[0069] Table 1 Performance test data of Examples 1.1-1.2 and Comparative Example 1

[0070] Compression strength / Mpa <![CDATA[Fracture toughness / (MN / m 3 / 2 )]]> Example 1.11 50 8.68 Example 1.12 49 8.62 Example 1.13 48 8.63 Example 1.21 24 5.64 Example 1.22 25 5.68 Example 1.23 23 5.65 Comparative Example 1 13 4.80

[0071] From Table 1, it can be seen that the compressive strength and fracture toughness of the high-strength structural ceramics obtained in Examples 1.1-1.2 are higher than those in Comparative Example 1. This may be because the binder starch is added to the raw materials of Examples 1.1-1.2, so that during the calcination process, the starch shrinks and pulls more zirconium oxide powder into the pores of the alumina ore powder, so that the shrinkage of the alumina ore powder during the calcination process is effectively supported, thereby improving the compressive strength and fracture toughness of the obtained high-strength structural ceramics.

[0072] Example 1.1 and Example 1.2 were compared with amylopectin and amylose. The results showed that the high-strength structural ceramics produced in Example 1.1 were superior to the high-strength structural ceramics produced in Example 1.2 in terms of compressive strength and fracture toughness. This may be because when amylopectin shrinks due to heat compared to amylose, amylopectin is more likely to pull the zirconium oxide powder on the branches into the pores of the alumina ore powder, thereby forming support for the alumina ore powder and reducing the possibility of shrinkage of the alumina ore powder during crystal phase transformation.

[0073] Example 1.31

[0074] Different from Example 1.11, in Example 1.31, the total pore volume of the pores with a D50 particle size of 10 μm and a pore size of less than 2 μm is 0.11 cm 3 / g of alumina powder.

[0075] Example 1.32

[0076] Different from Example 1.11, in Example 1.32, the total pore volume of the pores with a D50 particle size of 33 μm and a pore size of less than 2 μm is 0.21 cm 3 / g of alumina powder.

[0077] Example 1.33

[0078] Different from Example 1.11, in Example 1.33, the total pore volume of the pores with a D50 particle size of 70 μm and a pore size of less than 2 μm is 0.28 cm 3 / g of alumina powder.

[0079] Example 1.34

[0080] Different from Example 1.11, in Example 1.34, the total pore volume of the pores with a D50 particle size of 90 μm and a pore size of less than 2 μm is 0.29 cm 3 / g of alumina powder.

[0081] Comparative Example 2

[0082] Different from Example 1.11, in Comparative Example 2, the total pore volume of the pores with a D50 particle size of 3 μm and a pore size of less than 2 μm is 0.03 cm 3 / g of alumina powder.

[0083] Comparative Example 3

[0084] Different from Example 1.11, in Comparative Example 3, the total pore volume of the pores with a D50 particle size of 100 μm and a pore size of less than 2 μm is 0.33 cm 3 / g of alumina powder.

[0085] The high-strength structural ceramics prepared in Example 1.3 and Comparative Examples 2-3 were subjected to performance testing of compressive strength and fracture toughness. The test results are shown in Table 2.

[0086] Table 2 Performance test data of Example 1.3 and Comparative Examples 2-3

[0087] Compression strength / Mpa <![CDATA[Fracture toughness / (MN / m 3 / 2 )]]> Example 1.31 48 8.63 Example 1.32 49 8.62 Example 1.33 50 8.68 Example 1.34 50 8.62 Comparative Example 2 22 5.80 Comparative Example 3 21 6.10

[0088] Combining Table 1 and Table 2, it can be seen that Examples 1.11, 1.3 and Comparative Examples 2-3 are compared for different D50 particle sizes of alumina ore powder and the total pore volume of pores with a pore size of less than 2 μm. From the test results, it can be seen that the high-strength structural ceramics prepared in Examples 1.11 and 1.3 are superior to the high-strength structural ceramics prepared in Comparative Examples 2-3 in terms of compressive strength and fracture toughness. This may be because the D50 particle size of the alumina ore powder selected in Comparative Example 2 and the total pore volume of pores with a pore size of less than 2 μm are too small, making it difficult for the zirconium oxide powder to fully penetrate the pores. The zirconium oxide powder enters the pores of the alumina ore powder, making it difficult to support the alumina ore powder, so that the alumina ore powder shrinks violently at high temperatures, thereby affecting the compressive strength and fracture toughness of the obtained high-strength structural ceramics; the D50 particle size of the alumina ore powder selected in Comparative Example 3 and the total pore volume of pores with a pore size of less than 2 μm are too large, and it is difficult for the zirconium oxide powder to completely fill the pores of the alumina ore powder. The zirconium oxide powder entering the alumina ore powder is difficult to support the force of the violent contraction of the alumina ore powder at high temperatures, thereby affecting the compressive strength and fracture toughness of the obtained high-strength structural ceramics.

[0089] Example 1.41

[0090] A high-strength structural ceramic is prepared by the following steps:

[0091] 51 g of zirconium oxide powder and 1 g of sodium hexametaphosphate were mixed to prepare a premix;

[0092] 14 g of pullulan was added to the premix and mixed to prepare a mixture;

[0093] To the prepared mixture, 40 g of water and 34 g of a total pore volume of 0.26 cm 3 / g of alumina ore powder (the D50 particle size of pores with a pore size of less than 2 μm is 50 μm) and mixed, heated to 40°C and maintained for 2 hours, and then washed with water to prepare a washed material;

[0094] The prepared washed material is subjected to cold isostatic pressing and calcined to obtain high-strength structural ceramics.

[0095] Example 1.42

[0096] The difference from Example 1.41 is that 0.5 g of sodium hexametaphosphate is added in Example 1.42.

[0097] Example 1.43

[0098] The difference from Example 1.41 is that 1.5 g of sodium hexametaphosphate is added in Example 1.43.

[0099] The high-strength structural ceramics prepared in Example 1.4 were subjected to performance testing of compressive strength and fracture toughness. The test results are shown in Table 3.

[0100] Table 3 Performance test data of Example 1.4

[0101] Compression strength / Mpa <![CDATA[Fracture toughness / (MN / m 3 / 2 )]]> Example 1.41 57 10.85 Example 1.42 56 10.82 Example 1.43 55 10.83

[0102] Combining Table 1 and Table 3, it can be seen that Examples 1.41-1.43 and Example 1.11 are compared with respect to the addition of dispersant sodium hexametaphosphate in the raw materials. The results show that sodium hexametaphosphate is added to the raw materials of Examples 1.41-1.43, and the high-strength structural ceramics obtained perform better in terms of compressive strength and fracture toughness. This may be because sodium trimetaphosphate produced by the hydrolysis of sodium hexametaphosphate causes starch cross-linking. At this time, amylopectin can more easily pull zirconium oxide powder into the pores of alumina ore powder, thereby forming support for the alumina ore powder, reducing the possibility of drastic shrinkage of the alumina ore powder during crystal phase transformation, and thereby improving the compressive strength and fracture toughness of the high-strength structural ceramics.

[0103] Example 1.51

[0104] A high-strength structural ceramic is prepared by the following steps:

[0105] 56 g of zirconium oxide powder and 1 g of sodium hexametaphosphate were mixed to prepare a premix;

[0106] 14 g of pullulan was added to the premix and mixed to prepare a mixture;

[0107] To the prepared mixture, 40 g of water and 30 g of a total pore volume of 0.26 cm 3 / g of alumina ore powder (the D50 particle size of pores with a pore size of less than 2 μm is 50 μm) and mixed, heated to 40°C and maintained for 2 hours, and then washed with water to prepare a washed material;

[0108] The prepared washed material is subjected to cold isostatic pressing and calcined to obtain high-strength structural ceramics.

[0109] Example 1.52

[0110] The difference from Example 1.51 is that 46 g of zirconium oxide powder and 38 g of a total pore volume of 0.26 cm were added to Example 1.52. 3 / g of alumina mineral powder (the D50 particle size of pores with a pore size of 2 μm or less is 50 μm).

[0111] The high-strength structural ceramics prepared in Example 1.5 were subjected to performance testing of compressive strength and fracture toughness. The test results are shown in Table 4.

[0112] Table 4 Performance test data of Example 1.5

[0113] Compression strength / Mpa <![CDATA[Fracture toughness / (MN / m 3 / 2 )]]> Example 1.51 56 10.83 Example 1.52 55 10.82

[0114] From Tables 3 and 4, it can be seen that Example 1.41 and Example 1.5 compare different ratios of zirconium oxide powder and aluminum oxide slag. From the performance test results, it can be seen that the compressive strength and fracture toughness of the high-strength structural ceramics prepared in Example 1.41 are not much different from the compressive strength and fracture toughness of the high-strength structural ceramics prepared in Examples 1.51-1.52. This shows that the ratios of zirconium oxide powder and aluminum oxide slag selected in Examples 1.41, 1.51 and 1.52 are all beneficial to improving the compressive strength and fracture toughness of the high-strength structural ceramics.

[0115] Example 2

[0116] Example 2.11

[0117] Different from Example 1.41, Example 2.11 uses an equal amount of stabilized zirconium oxide powder with a D50 particle size of 45 nm from Preparation Example 2.

[0118] Example 2.12

[0119] Different from Example 1.41, Example 2.12 uses an equal amount of stabilized zirconium oxide powder with a D50 particle size of 45 nm from Preparation Example 1.

[0120] Example 2.13

[0121] Different from Example 1.41, Example 2.13 uses an equal amount of stabilized zirconium oxide powder with a D50 particle size of 45 nm from Preparation Example 3.

[0122] The high-strength structural ceramics prepared in Example 2.1 were subjected to performance testing of compressive strength and fracture toughness. The test results are shown in Table 5.

[0123] Table 5 Performance test data of Example 2.1

[0124] Compression strength / Mpa <![CDATA[Fracture toughness / (MN / m 3 / 2 )]]> Example 2.11 78 12.00 Example 2.12 75 11.92 Example 2.13 70 11.69

[0125] As can be seen from Tables 3 and 5, Example 1.41 and Example 2.1 are compared with respect to the zirconium oxide powder added to the raw materials. Examples 2.11-2.13, in which the stabilized zirconium oxide powder prepared in the Preparation Example was added, produced high-strength structural ceramics that were superior to those of Example 1.41 in terms of compressive strength and fracture toughness. This is likely due to the fact that during the stable oxidation of magnesium, magnesium ions dissolve in the zirconium oxide, replacing zirconium ions in the zirconium oxide and forming a substitutional solid solution. This partially stabilizes the zirconium oxide with magnesium, preventing the tetragonal to monoclinic transformation of the zirconium oxide, and thus steadily lowering the phase transition point of the zirconium oxide to room temperature. This reduces the possibility of zirconium oxide shrinking at high temperatures, thereby providing stable support for the alumina ore powder and improving the compressive strength and fracture toughness of the resulting high-strength structural ceramics.

[0126] Examples 2.11-2.13 compared stabilized zirconia powders obtained from different raw material ratios. The results showed that the raw material ratio of stabilized zirconia in Example 2.13 was 3:100, which was greater than the raw material ratio of stabilized zirconia selected in Examples 2.11 and 2.12. The high-strength structural ceramics prepared in Examples 2.11 and 2.12 were superior to those in Example 2.13 in terms of compressive strength and fracture toughness. This shows that the raw material ratio of stabilized zirconia selected in this application is more conducive to improving the compressive strength and fracture toughness of high-strength structural ceramics.

[0127] Example 2.2

[0128] A high-strength structural ceramic is prepared by the following steps:

[0129] A premix was prepared by mixing 51 g of the stabilized zirconium oxide powder (D50 particle size of 45 nm) from Preparation Example 2 with 1 g of sodium hexametaphosphate;

[0130] The total pore volume of 34g is 0.26cm 3 / g of alumina mineral powder (the D50 particle size of pores with a pore size of less than 2 μm is 50 μm) is mixed with 14 g of pullulan to prepare a mixture;

[0131] The prepared mixed material and premix were mixed, 40 g of water was added and mixed, the mixture was heated to 40° C. and maintained for 2 h, and then washed with water to prepare a washed material;

[0132] The prepared washed material is subjected to cold isostatic pressing and calcined to obtain high-strength structural ceramics.

[0133] Example 2.3

[0134] A high-strength structural ceramic is prepared by the following steps:

[0135] 51 g of stabilized zirconium oxide powder (D50 particle size of 45 nm) from Preparation Example 2 was mixed with 7 g of pullulan to prepare a premix; 34 g of a total pore volume of 0.26 cm 3 / g of alumina mineral powder (the D50 particle size of pores with a pore size of less than 2 μm is 50 μm) is mixed with 7g of pullulan to prepare a mixture;

[0136] 1 g of sodium hexametaphosphate and 40 g of water were added to the obtained mixture and premix, mixed, heated to 40° C. and maintained for 2 h, and then washed with water to obtain a washed material;

[0137] The prepared washed material is subjected to cold isostatic pressing and calcined to obtain high-strength structural ceramics.

[0138] Comparative Example 4

[0139] A high-strength structural ceramic is prepared by the following steps:

[0140] 51 g of stabilized zirconium oxide powder (D50 particle size of 45 nm) from Preparation Example 2 was mixed with 34 g of a total pore volume of 0.26 cm 3 / g of alumina ore powder (the D50 particle size of pores with a pore size of less than 2 μm is 50 μm) to prepare a premix;

[0141] 1 g of sodium hexametaphosphate and 14 g of pullulan were added to the premix and mixed to prepare a mixture;

[0142] 40 g of water was added to the obtained mixture and mixed, and the mixture was heated to 40° C. and maintained for 2 h, and then washed with water to obtain a washed material;

[0143] The prepared washed material is subjected to cold isostatic pressing and calcined to obtain high-strength structural ceramics.

[0144] The high-strength structural ceramics prepared in Examples 2.2-2.3 and Comparative Example 4 were subjected to performance testing of compressive strength and fracture toughness. The test results are shown in Table 6.

[0145] Table 6 Performance test data of Examples 2.2-2.3 and Comparative Example 4

[0146] Compression strength / Mpa <![CDATA[Fracture toughness / (MN / m 3 / 2 )]]> Example 2.2 11 4.50 Example 2.3 16 5.48 Comparative Example 4 28 7.52

[0147] Combining Tables 5 and 6, it can be seen that Example 2.11, Example 2.2, Example 2.3 and Comparative Example 4 are compared for different preparation methods of high-strength structural ceramics. From the test results, it can be seen that the high-strength structural ceramics prepared in Example 2.11 are superior to Comparative Example 4 in terms of compressive strength and fracture toughness. Therefore, it can be seen that the preparation method of high-strength structural ceramics selected in Example 2.11 of the present application is better in improving the compressive strength and fracture toughness of high-strength structural ceramics. This may be because Example 2.11 uses sodium hexametaphosphate, which has a good dispersing effect on nano-zirconia. At the same time, starch is wrapped on the surface of zirconia and then filled into the pores on the surface of alumina, which is conducive to subsequent water washing and cross-linking. As the calcination process proceeds, the amylopectin shrinks and pulls the zirconia into the pores.

[0148] In Comparative Example 4, zirconium oxide powder and alumina ore powder are first mixed, and then the dispersant sodium hexametaphosphate and starch are wrapped around the outside of the zirconium oxide powder and alumina ore powder. At this time, sodium hexametaphosphate cannot play the role of dispersant and cross-linking agent; while in Examples 2.2 and 2.3, alumina is first mixed with all or part of the starch. In this way, the starch first fills the pores of alumina, hindering the effective filling of zirconium oxide. During the calcination process, the starch shrinks until it disappears, and the pores of alumina are incompletely filled, making it difficult to effectively support the shrinkage stress generated by the alumina ore powder during high-temperature calcination. Therefore, the experimental results of Example 2.11 are greater than Comparative Example 4, greater than Example 2.23, and greater than Example 2.22.

[0149] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A method for preparing high-strength structural ceramics, characterized in that: The following steps are involved: 46-56 parts by weight of zirconium oxide powder and 10-18 parts by weight of starch are mixed, and then mixed with 30-38 parts by weight of aluminum oxide powder to prepare a mixture; The obtained mixture is subjected to cold isostatic pressing and calcined to obtain high-strength structural ceramics; The starch is amylopectin; Before mixing the zirconium oxide powder with the starch, the zirconium oxide powder is first mixed with 0.5-1.5 parts by weight of a dispersant to prepare a premix, wherein the dispersant is sodium hexametaphosphate.

2. The method for preparing a high-strength structural ceramic according to claim 1, wherein: The zirconium oxide powder is a stable zirconium oxide powder, which is prepared from magnesium chloride and zirconium oxychloride in a weight ratio of (1-2):

100.

3. The method for preparing a high-strength structural ceramic according to claim 2, characterized in that: The D50 particle size of the stabilized zirconia powder is 45±5 nm.

4. The method for preparing a high-strength structural ceramic according to claim 1, wherein: The D50 particle size of the alumina ore powder is 10-90 μm, and the total pore volume of the pores with a pore size of less than 2 μm is 0.11-0.29 cm 3 / g.

5. The method for preparing a high-strength structural ceramic according to claim 1, wherein: After the mixed material is prepared, 40±10 parts of water are added to the prepared mixed material, the temperature is raised to 40±10° C., and the mixture is maintained for 2±1 hours, and then washed with water to prepare a washed material.

6. A high-strength structural ceramic produced by the method for producing high-strength structural ceramic according to any one of claims 1 to 5.