Zirconium oxide ceramic matrix with high thermal shock resistance, preparation method and application

Abstract

The invention discloses a zirconia ceramic matrix with high thermal shock resistance as well as a preparation method and application thereof. The zirconia ceramic matrix comprises a matrix and a coating layer a; the matrix comprises the following components: 90-98 wt% of zirconium oxide; 1.5 to 8 wt.% of a stabilizing agent; % of a grain boundary regulating agent; the stabilizing agent is prepared from the following components in percentage by weight: 2.0 to 4.0 percent of Sc2O3, 0.5 to 1.5 percent of Yb2O3 and 0.3 to 1.0 percent of Er2O3; the grain boundary regulating agent is a composition of a boron source and an aluminum source; in the coating layer a, the molar ratio of zirconium to aluminum is (2-3): 1; and the component 1 is polyvinyl alcohol or polyvinylpyrrolidone. The fracture toughness, bending strength and thermal shock resistance of the ceramic matrix are effectively improved, and the overall mechanical property is remarkably improved. When the material bears thermal shock, the thermal shock resistance of the material is improved, and the application scene of the zirconia ceramic material is expanded.

Description

Technical Field

[0001] This invention relates to the field of zirconia ceramic materials technology, and in particular to a zirconia ceramic matrix with high thermal shock resistance, its preparation method, and its application. Background Technology

[0002] Zirconia ceramics have broad application prospects in engineering due to their excellent properties such as high temperature resistance and corrosion resistance. However, their high coefficient of thermal expansion and poor thermal shock resistance greatly limit their application range and service life. In multilayer composite ceramic materials, when the difference in the coefficients of thermal expansion between different materials is too large, residual stress will be generated due to thermal expansion mismatch, leading to coating cracking or even delamination. By designing and controlling the interface, prestressed ceramics can be fully prepared, thereby improving the strength, toughness, and thermal shock resistance of the ceramic material. High thermal shock resistant zirconia ceramic matrices can buffer stress through the synergistic effect of the coating layer and the matrix, avoiding stress concentration that leads to matrix cracking, and significantly improving its stability. They can be widely used in precision machinery, aerospace, medical devices, and other fields. Zirconia ceramic matrix refers to ceramic matrix materials prepared by adding appropriate stabilizers to zirconia as the main component and through processes such as molding and sintering. It is usually used as the continuous phase in composite ceramic systems to support and fix the reinforcing phase structure. This type of matrix material has high hardness, strength and good thermal stability, which can provide basic mechanical support and structural stability for composite ceramic materials.

[0003] In composite ceramic materials, the zirconia ceramic matrix not only bears the responsibility of load transfer but also significantly influences the dispersion state of the reinforcing phase, the interfacial bonding mode, and the crack propagation path. By controlling the phase composition, grain size, and grain boundary structure of the matrix, the overall mechanical properties and service stability of the composite system can be affected to a certain extent. Therefore, the design and optimization of the zirconia ceramic matrix in composite ceramic materials is a crucial foundation for achieving composite toughening and synergistic performance improvement.

[0004] However, existing zirconia matrices generally suffer from insufficient interfacial bonding with the reinforcing phase. Due to the low surface activity of the matrix, poor interfacial wettability and chemical compatibility, reinforcing phases such as Al2O3, SiC, or carbon nanomaterials easily form weak interfacial layers or pores within the matrix. These weak interfaces can become crack initiation zones, weakening the toughness-enhancing effect of the composite material. Simultaneously, the matrix has limited dispersion ability for the reinforcing phase, and powder mixing typically requires complex processes to achieve good uniformity.

[0005] Furthermore, existing zirconia ceramic matrices are prone to insufficient densification or abnormal grain growth during sintering, resulting in structural defects such as micropores and high grain boundary energy in the final material. The inhomogeneity of the matrix microstructure not only reduces the final mechanical properties of the composite ceramics but also affects their thermal shock resistance, thus restricting their widespread application in high-end structural and functional ceramics.

[0006] In summary, there is an urgent need to provide a zirconia ceramic matrix material that is structurally stable, has good interfacial compatibility, and possesses excellent thermal shock resistance, in order to improve the overall performance of composite ceramic materials. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention proposes a highly thermally shock zirconia ceramic matrix, its preparation method, and its applications.

[0008] This invention provides a zirconia ceramic matrix with high thermal shock resistance, the zirconia ceramic matrix comprising a matrix and a coating layer a; The matrix comprises the following components: Zirconia 90-98 wt.%; stabilizer 1.5-8 wt.%; grain boundary modifier 0.05-2 wt.%; The stabilizer is 2.0–4.0 wt.% Sc2O3, 0.5–1.5 wt.% Yb2O3, and 0.3–1.0 wt.% Er2O3; The grain boundary regulator is a combination of a boron source and an aluminum source; The preparation method of the coating layer a includes the following steps: Zirconia, aluminum source, phosphorus source and component 1 are added to a solvent and dispersed by stirring or ultrasonication to prepare the coating solution; In the coating layer a, the molar ratio of zirconium to aluminum is (2~3):1; Component 1 is polyvinyl alcohol or polyvinylpyrrolidone. PVA / PVP molecules contain hydroxyl and pyrrolidone functional groups, which can coordinate with the surface of zirconium oxide and aluminum source particles, increasing electrostatic repulsion between particles and thus preventing particle agglomeration. Furthermore, during heat treatment, PVA / PVP thermally decomposes and volatilizes, forming microchannels that can be filled by flowing zirconium oxide and aluminum particles during high-temperature sintering, promoting the densification of the coating layer and simultaneously forming a microstructural gradient, which helps with stress dispersion.

[0009] In this invention, the stabilizer is a combination of Sc2O3, Yb2O3, and Er2O3, wherein Sc 3+ With its smaller ionic radius, Yb preferentially occupies lattice sites, effectively stabilizing the tetragonal phase and preventing its transformation to the monoclinic phase; 3+ and Er 3+It can accumulate at grain boundaries, forming a grain boundary strengthening layer that can inhibit abnormal grain growth. By controlling the ratio and total content of the stabilizer, a uniform solid solution effect can be formed in the crystal lattice, improving the overall toughness of the matrix while limiting grain size growth and reducing stress concentration, thereby significantly enhancing fracture toughness and flexural strength. In addition, due to the differences in the radii and charges of the three ions, distortion and micro-stress fields are generated within the crystal lattice, which can effectively inhibit the initiation and propagation of microcracks.

[0010] In this invention, the aluminum source in coating layer a can form an aluminum-oxygen network structure during the subsequent curing process. On the one hand, this improves the density and mechanical strength of the coating layer. On the other hand, by adjusting the coefficient of thermal expansion of the coating, it can form a gradient matching relationship with the substrate and adjacent coatings. The phosphorus source can introduce a phosphorus-oxygen bond structure into the system, forming a stable crystalline phase with low coefficient of thermal expansion with the zirconium and aluminum components, and promoting the formation of an intermediate layer at the interface between the coating and the zirconium oxide substrate. This achieves the purpose of enhancing the interfacial bonding force between the coating layer and the substrate, extending the service life of the material, and preventing the coating from peeling off due to excessive difference in coefficient of thermal expansion between the coating and the substrate.

[0011] Preferably, the D50 average particle size of the zirconium oxide is 50~300 nm, which is determined using a laser particle size analyzer (MalvernMastersizer 3000).

[0012] Preferably, the solvent is anhydrous ethanol.

[0013] In some embodiments, the coating layer is a double-layer coating structure, including an inner coating layer and an outer coating layer; The method for preparing the outer coating layer includes the following steps: 10-30 wt.% Ti3AlC2 and 0.1-2 wt.% component 1 are added to a solvent and dispersed by stirring or ultrasonication to prepare the outer coating layer solution; The inner coating layer is coating layer a.

[0014] In this invention, the layered crystal structure of the outer coating layer Ti3AlC2 can release some stress under thermal shock through interlayer slip and crack deflection. By synergistically matching the coating thickness and thermal expansion coefficient, this invention creates a favorable residual stress distribution within the coating-substrate system during cooling and thermal cycling. Specifically, due to the gradient difference in thermal expansion behavior between the outer and inner coating layers, and between the inner coating layer and the zirconia ceramic substrate, mutually restraining tensile-compressive stress zones are induced near the interfaces. This establishes a residual stress field dominated by compressive stress on the material surface and near the surface, which can passivate and shield crack tips, reducing the effective stress intensity factor at the crack tip and thus inhibiting crack initiation and propagation. Simultaneously, the gradual transition of interlayer stress effectively alleviates stress concentration at single interfaces, preventing interface delamination or brittle fracture. Through this stress regulation mechanism, the double-layer coating structure achieves a synergistic improvement in the fracture toughness and thermal shock resistance reliability of the zirconia ceramic substrate without introducing significant internal stress instability risks.

[0015] In some embodiments, the boron source is boric acid or tetraborate.

[0016] In some embodiments, the aluminum source is aluminum oxide, aluminum salt, or aluminum alkoxide.

[0017] In some embodiments, the phosphorus source is phosphoric acid or a soluble salt thereof, wherein the soluble salt is ammonium dihydrogen phosphate, potassium dihydrogen phosphate, or diamine hydrogen phosphate.

[0018] In this invention, the boron source and the aluminum source can work synergistically to form a composite grain boundary phase characterized by a BO-Al bond structure, which together form a stable, dense, and crack-resistant grain boundary network, effectively improving the overall mechanical properties of the ceramic.

[0019] In some embodiments, the mass ratio of boron source to aluminum source in the grain boundary regulator is (1-6):(1-10).

[0020] In some embodiments, the thickness of the coating layer is 3 to 10 μm.

[0021] In this invention, the coating layer serves as a surface functional layer, using PVA / PVP as a dispersing and binding agent. After high-temperature sintering, the PVA / PVP volatilizes through thermal decomposition, and the ceramic particles grow tightly together through sintering neck growth, ultimately forming a dense and continuous composite layer. This reduces the negative impact of micropores and grain boundary defects on mechanical properties. Furthermore, the coating layer can absorb and disperse some thermal stress, reducing stress concentration on the substrate surface, thereby delaying crack initiation and propagation.

[0022] This invention also provides a method for preparing the zirconia ceramic matrix, comprising the following steps: S1: Weigh zirconium oxide and stabilizer according to mass percentage, pre-calcine them, add grain boundary regulator, mix evenly, shape and sinter twice to obtain the matrix; S2: Prepare a coating solution for forming a coating layer; S3: The coating solution is applied to the surface of the zirconia ceramic substrate and then heat-treated to obtain the zirconia ceramic substrate.

[0023] In some embodiments, the molding method described in step S1 is any one of dry pressing, isostatic pressing, or slip casting. The sintering temperature is 1350–1600℃, and the sintering time is 1–4 h.

[0024] In some embodiments, the coating method described in step S3 is any one of dip coating, spin coating, or spray coating.

[0025] In some embodiments, the heat treatment in step S3 is performed at a temperature of 600–1300°C for a time of 0.5–6 h.

[0026] The present invention also provides the application of the zirconia ceramic matrix in the preparation of composite ceramic materials.

[0027] In summary, compared with the prior art, the present invention achieves the following technical effects: 1. This invention effectively improves the fracture toughness, flexural strength and thermal shock resistance of the zirconia ceramic matrix by regulating the stabilizer and designing the coating layer, making the material more crack-resistant when subjected to external forces and significantly improving the overall mechanical properties, thereby meeting the needs of high-strength structural applications.

[0028] 2. The ceramic matrix prepared using this invention exhibits superior thermal stability under thermal shock and high-temperature environments. The synergistic effect of the coating layer and the grain boundary regulator effectively reduces the risk of thermal stress concentration and structural damage, enabling the material to maintain structural integrity and mechanical properties under high-temperature cycling or rapid temperature change conditions, thus broadening its application potential under high-temperature and harsh working conditions.

[0029] 3. This invention, through the introduction of grain boundary regulators and coating layer formation strategies, achieves uniform grain size and good densification within the ceramic matrix, significantly reducing micropores and grain boundary defects. This enhances the material's stability and processing consistency, providing a reliable foundation for the subsequent preparation of composite or functional ceramics.

[0030] 4. By introducing a double-layer coating system, this invention can form a favorable residual stress distribution, inhibit crack initiation and propagation, thereby improving the fracture toughness and structural reliability of the ceramic matrix, and helping to improve the thermal stability and service life of the material. It is suitable for the field of structural ceramics with high requirements for mechanical properties and thermal shock resistance. Detailed Implementation

[0031] To enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0032] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, all materials and reagents used are commercially available. Example 1

[0033] Raw material: Zirconia powder: 949g tetragonal zirconia, D50 average particle size of about 120 nm.

[0034] Stabilizers: 30 g Sc2O3, 10 g Yb2O3 and 6 g Er2O3.

[0035] Grain boundary regulator: 1g boric acid and 4g aluminum oxide.

[0036] The method for preparing the zirconia ceramic matrix in this embodiment includes the following steps: Step 1: After weighing and mixing the zirconium oxide powder with the stabilizer, add about 1500g of anhydrous ethanol as a dispersion medium to make the solid content of the slurry 40 wt%, and mix by ball milling for 12 h. After drying, the mixed slurry is pre-calcined at 1000℃ for 2 hours to promote the initial solid solution of the stabilizer in the zirconium oxide lattice.

[0037] Step 2: Add the pre-calcined powder back into ethanol, add the weighed boric acid and alumina powder, and continue ball milling and mixing for 8 hours to ensure that the grain boundary regulator is uniformly dispersed in the zirconium oxide powder; after ball milling, dry to obtain composite ceramic powder.

[0038] Step 3: The obtained composite ceramic powder was added to a 2wt% polyvinyl alcohol aqueous solution as a molding aid, and a green body was prepared by dry pressing; subsequently, a secondary sintering was carried out in an air atmosphere. The sintering process was as follows: heating to 1500℃, holding for 2 h, and cooling in the furnace. After sintering, a densified zirconia ceramic matrix was obtained.

[0039] Step 4: Weigh out 61 g of nano-zirconia powder (D50 approximately 80 nm), 40 g of aluminum nitrate, and 1.5 g of ammonium dihydrogen phosphate; and 0.5 g of polyvinylpyrrolidone (PVP, molecular weight approximately 40,000). Add the above raw materials to anhydrous ethanol, with the solid content controlled at 30 wt%. Stir magnetically for 30 min, then ultrasonically disperse for 20 min to obtain a uniform and stable coating solution.

[0040] Step 5: Clean and dry the sintered zirconia ceramic substrate with ethanol; then apply the coating solution to the substrate surface by dip coating, controlling the single dip coating speed to 5 mm / s, and repeat the dip coating twice and combine with intermediate drying treatment to control the coating thickness to about 5 μm.

[0041] Step 6: After coating, the sample is placed in an air atmosphere for heat treatment. The heat treatment process is as follows: heat up to 900℃, hold for 2 hours, and cool naturally. After heat treatment, it is completely decomposed and forms a dense and continuous composite coating layer on the substrate surface. Example 2

[0042] Raw material: Zirconia powder: 952g tetragonal zirconia, D50 average particle size of about 120 nm.

[0043] Stabilizers: 25 g Sc2O3, 12 g Yb2O3 and 6 g Er2O3.

[0044] Grain boundary regulator: 2g boric acid and 3g aluminum oxide.

[0045] The method for preparing the zirconia ceramic matrix in this embodiment includes the following steps: Step 1: After weighing and mixing the zirconium oxide powder with the stabilizer, add about 1800g of anhydrous ethanol as a dispersion medium to make the solid content of the slurry 35 wt%, and mix by ball milling for 16 h. After drying, the mixed slurry is pre-calcined at 1050℃ for 3 hours to promote the initial solid solution of the stabilizer in the zirconium oxide lattice.

[0046] Step 2: Add the pre-calcined powder back into ethanol, add the weighed boric acid and alumina powder, and continue ball milling and mixing for 8 hours to ensure that the grain boundary regulator is uniformly dispersed in the zirconium oxide powder; after ball milling, dry to obtain composite ceramic powder.

[0047] Step 3: The obtained composite ceramic powder was added to a 2wt% polyvinyl alcohol aqueous solution as a molding aid, and a green body was prepared by dry pressing; subsequently, a second sintering was carried out in an air atmosphere. The sintering process was as follows: heating to 1550℃, holding for 3 h, and then cooling in the furnace. After sintering, a densified zirconia ceramic matrix was obtained, whose phase structure was dominated by a stable tetragonal phase and the grain size distribution was uniform.

[0048] Step 4: Weigh out 72 g of nano-zirconia powder (D50 approximately 80 nm), 36 g of aluminum nitrate, and 1.5 g of ammonium dihydrogen phosphate; and 0.8 g of polyvinylpyrrolidone (PVP, molecular weight approximately 40,000). Add the above raw materials to anhydrous ethanol, with the solid content controlled at 30 wt%. Stir magnetically for 30 min, then ultrasonically disperse for 20 min to obtain a uniform and stable coating solution.

[0049] Step 5: Clean and dry the sintered zirconia ceramic substrate with ethanol; then apply the coating solution to the substrate surface by dip coating, controlling the single dip coating speed to 5 mm / s, and repeat the dip coating twice and combine with intermediate drying treatment to control the coating thickness to about 5 μm.

[0050] Step 6: After coating, the sample is placed in an air atmosphere for heat treatment. The heat treatment process is as follows: heat up to 1100℃, hold for 1.5 h, and cool naturally. After heat treatment, it is completely decomposed and a dense and continuous composite coating layer is formed on the substrate surface. Example 3

[0051] Except for the stabilizers, which are 35 g Sc2O3, 12 g Yb2O3 and 6 g Er2O3, the composition of the other raw materials and the preparation steps are the same as in Example 1. Example 4

[0052] Except for step 4, where the solid content is controlled at 20 wt%, the composition of the raw materials and the preparation steps are the same as in Example 1. Example 5

[0053] Except for step 4, in which nano-zirconia powder (D50 about 80 nm, 61 g) and aluminum nitrate 40 g and polyvinyl alcohol (PVA, molecular weight about 30000, 0.5 g) are weighed, the other raw materials are composed and the preparation steps are the same as in Example 1. Example 6

[0054] The difference from Example 1 is that in step 4, 61 g of nano-zirconia powder (D50 approximately 80 nm, 61 g), 40 g of aluminum nitrate, and 1.5 g of ammonium dihydrogen phosphate were weighed; 0.5 g of polyvinylpyrrolidone (PVP, molecular weight approximately 40,000) was also weighed. These raw materials were added to anhydrous ethanol, with the solid content controlled at 30 wt%. The mixture was magnetically stirred for 30 min, followed by ultrasonic dispersion for 20 min to obtain a uniform and stable inner coating solution. 0.5 g of polyvinylpyrrolidone (PVP, molecular weight approximately 40,000) was weighed and added to 100 g of anhydrous ethanol. The solution was fully dissolved to form a stable solution. 15 g of Ti3AlC2 powder was added, and the mixture was magnetically stirred for 30 min, followed by ultrasonic treatment for 15 min to prepare a uniform and stable outer coating solution.

[0055] In step 5, the sintered zirconia ceramic substrate surface is cleaned with ethanol and dried; then, the inner coating solution is applied to the substrate surface by dip coating, with the single dip coating speed controlled at 5 mm / s. After two dip coatings and intermediate drying, the coating thickness is controlled at approximately 2.5 μm. After the inner layer is dried, the outer coating solution is applied to the substrate surface by dip coating, with the single dip coating speed controlled at 5 mm / s. After two dip coatings and intermediate drying, the coating thickness is controlled at approximately 2.5 μm.

[0056] Comparative Example 1

[0057] Except for the stabilizer, which is 46 g Sc2O3, the composition of the other raw materials and the preparation steps are the same as in Example 1. Comparative Example 2

[0058] Except for the stabilizers, which are 30 g Sc2O3 and 16 g Yb2O3, the composition of the other raw materials and the preparation steps are the same as in Example 1. Comparative Example 3

[0059] Except for the grain boundary regulator being 5g of boric acid, the composition of the other raw materials and the preparation steps are the same as in Example 1. Comparative Example 4

[0060] Except for the grain boundary regulator being 5 g of alumina, the composition of the other raw materials and the preparation steps are the same as in Example 1. Comparative Example 5

[0061] Except that the zirconia ceramic matrix in this comparative example does not contain a coating layer, the composition of the other raw materials and the preparation steps are the same as in Example 1. Comparative Example 6

[0062] Raw material: Zirconia powder: 949g tetragonal zirconia, D50 average particle size of about 120 nm.

[0063] Stabilizers: 30 g Sc2O3, 10 g Yb2O3 and 6 g Er2O3.

[0064] Grain boundary regulator: 1g boric acid and 4g aluminum oxide.

[0065] The method for preparing the zirconia ceramic matrix in this embodiment includes the following steps: Step 1: After weighing and mixing the zirconium oxide powder with the stabilizer, add about 1500 g of anhydrous ethanol as a dispersion medium to make the solid content of the slurry 40 wt%. Mix by ball milling for 12 h. After ball milling, dry the slurry directly to obtain the mixed powder.

[0066] Step 2: Add the mixed powder obtained in Step 1 back into ethanol, add the weighed boric acid and alumina powder, and continue ball milling for 8 hours. After ball milling, perform drying treatment to obtain composite ceramic powder.

[0067] Step 3: The obtained composite ceramic powder was added to a 2wt% polyvinyl alcohol aqueous solution as a molding aid, and a green body was prepared by dry pressing; subsequently, a secondary sintering was carried out in an air atmosphere. The sintering process was as follows: heating to 1500℃, holding for 2 h, and cooling in the furnace. After sintering, a densified zirconia ceramic matrix was obtained.

[0068] Step 4: Weigh out 61 g of nano-zirconia powder (D50 approximately 80 nm), 40 g of aluminum nitrate, and 1.5 g of ammonium dihydrogen phosphate; and 0.5 g of polyvinylpyrrolidone (PVP, molecular weight approximately 40,000). Add the above raw materials to anhydrous ethanol, with the solid content controlled at 30 wt%. Stir magnetically for 30 min, then ultrasonically disperse for 20 min to obtain a uniform and stable coating solution.

[0069] Step 5: Clean and dry the sintered zirconia ceramic substrate with ethanol; then apply the coating solution to the substrate surface by dip coating, controlling the single dip coating speed to 5 mm / s, and repeat the dip coating twice and combine with intermediate drying treatment to control the coating thickness to about 5 μm.

[0070] Step 6: After coating, the sample is placed in an air atmosphere for heat treatment. The heat treatment process is as follows: heat up to 900℃, hold for 2 hours, and cool naturally. After heat treatment, it is completely decomposed and forms a dense and continuous composite coating layer on the substrate surface. Test Example 1: Three-point flexural strength (MPa) test

[0071] The sintered samples were cut into rectangular strips with dimensions of 4mm × 3mm × 36mm using a WXD170 reciprocating diamond wire rotary point cutter. Referring to GB6569-1986, "Test Method for Bending Strength of Engineering Ceramics," the three-point bending strength of the infiltrated ceramic specimens was determined using the three-point bending method on a Shimadzu AG-10TA electronic universal testing machine. Test conditions: specimen test span 20 mm, indenter diameter 4 mm, pressure sensor range dp = 400N ± 0.25%, loading speed 0.5mm / min, ambient temperature 23℃, relative humidity 47%.

[0072] The test results are shown in Tables 1 and 2: Table 1. Three-point flexural strength test results (MPa) of Example 1 ; Table 2. Comparative Three-Point Bending Strength Test Results (MPa) ; The results in Tables 1-2 show that the zirconia ceramic matrices prepared in Examples 1-6 all exhibited high three-point flexural strength, and their overall flexural strength was significantly higher than that of the corresponding comparative samples, demonstrating excellent mechanical properties.

[0073] Compared to Example 1, Comparative Examples 1 and 2, using single or two-component stabilizer systems, exhibited significantly lower flexural strength than the Example 1, demonstrating that the synergistic use of the three stabilizers can exert a synergistic effect in stabilizing the crystal phase and suppressing unfavorable phase transformations. In Comparative Examples 3 and 4, the grain boundary regulators contained only boron or only aluminum sources, respectively, and their flexural strength was lower than that of the Example 1, which simultaneously introduced both boron and aluminum sources. This indicates that the combined introduction of boron and aluminum sources is beneficial for forming a more stable and uniform grain boundary structure, thereby improving the mechanical properties of the ceramic matrix. In Comparative Example 5, no coating layer was formed on the surface of the zirconia ceramic matrix, resulting in a significant decrease in flexural strength. This indicates that the coating layer can effectively passivate surface defects and reduce stress concentration, significantly improving flexural strength. In Comparative Example 6, the zirconia powder was not pre-sintered, leading to insufficient solid solution of the stabilizer. This resulted in decreased phase stability and microstructure uniformity of the sintered material, and its flexural strength was significantly lower than that of Example 1, further verifying the necessity of the pre-sintering step. The results show that the stabilizer content, grain boundary regulator composition, and coating preparation parameters have a significant impact on the mechanical properties of zirconia ceramic matrix. By optimizing each parameter in a synergistic manner within a reasonable range, a zirconia ceramic matrix with excellent mechanical properties can be obtained. Test Example 2: Fracture Toughness Test

[0074] The sintered samples were cut into rectangular strips with dimensions of 4mm × 3mm × 36mm using a WXD170 reciprocating diamond wire rotary point cutter. The fracture toughness Kc of the infiltrated ceramic specimens was determined using the three-point bending method on a Shimadzu AG-10TA electronic universal testing machine, referring to GB / T 4161-1984, "Test Method for Plane Strain Fracture Toughness Kc of Metallic Materials". Ic Test conditions: The test span of the specimen was 20 mm, the diameter of the indenter was 4 mm, the range of the pressure sensor was dp=400N±0.25%, the loading speed was 0.5 mm / min, the test environment temperature was 23℃, and the relative humidity was 47%.

[0075] The test results are shown in Tables 3 and 4: Table 3. Fracture toughness test results of the examples (MPa·m) 1 / 2 ) ; Table 4. Comparative fracture toughness test results (MPa·m) 1 / 2 ) ; The results in Tables 3 and 4 show that the fracture toughness of each sample initially increases and then slightly decreases with increasing sintering temperature, reaching a relatively high level around 1300℃. This trend indicates that a moderate sintering temperature is beneficial for obtaining a dense microstructure with suitable grain size, thereby promoting the synergistic effect of crack deflection, bifurcation, and phase transformation toughening mechanisms. Under the same sintering temperature conditions, the fracture toughness of the examples is significantly higher than that of the comparative samples, indicating that by controlling the composite stability ratio of Sc2O3, Yb2O3, and Er2O3, and combining it with boron-aluminum source synergistic grain boundary control, the phase stability and grain boundary structure of the zirconia matrix can be effectively optimized.

[0076] Comparative Examples 1 and 2, using single or two-component stabilizer systems, exhibited lower overall fracture toughness than the examples containing a composite stabilizer of three rare earth oxides, indicating that multi-component rare earth stabilizers are more effective in regulating phase composition and lattice distortion. Comparative Examples 3 and 4, introducing only boron or aluminum sources as grain boundary modifiers, showed significantly inferior fracture toughness and test stability compared to the boron-aluminum source combination system, demonstrating that a single grain boundary modifier method cannot simultaneously achieve densification and grain boundary stability. Comparative Example 6, without pre-sintering treatment, showed a lower mean fracture toughness and a significantly increased standard deviation, indicating that insufficient solid solution of the stabilizer leads to microstructure inhomogeneity, thus affecting the stability and repeatability of the material's mechanical properties. Test Example 3: Determination of Coefficient of Thermal Expansion

[0077] Thermal expansion curves of the samples from room temperature to 1000℃ were plotted on a TMA2940 thermomechanical analyzer. The heating rate was 20℃ / min. The measured data were input into the computer attached to the instrument, which automatically plotted the thermal expansion curves and provided the coefficient of thermal expansion within the temperature range ΔT. The coating layer was tested on a high-purity alumina sheet with a coating of the same thickness.

[0078] The test results are shown in Table 5: Table 5. Coefficients of thermal expansion (CTE) of different zirconia ceramic matrices (°C) -1 )) ; ; Table 5 shows that the results of each embodiment effectively controlled the thermal expansion matching between the coating and the substrate by setting a single or double coating layer on the surface of the zirconia ceramic substrate. The slightly higher CTE relative to the substrate can absorb a certain amount of thermal stress and improve thermal shock and thermal vibration performance. Example 6 uses a double coating layer to achieve thermal expansion stress matching by forming an internal and external CTE gradient, thereby reducing thermal stress concentration. In contrast, Comparative Example 5 has no coating, the difference in thermal expansion is small but surface defects are exposed, which easily leads to local thermal stress concentration; the stabilizer content of Comparative Examples 1 and 2 deviates from the appropriate range, the CTE of the substrate is slightly increased, which is not conducive to thermal expansion matching. Test Example 4: Thermal Shock Resistance Test

[0079] The samples were taken from the sintered zirconia ceramic matrix and cut into rectangular blocks with sides of approximately 10 mm × 10 mm × 3 mm. The samples were dried to constant weight before testing to avoid moisture affecting the thermal cycling. Thermal shock performance testing was conducted according to GB / T 37246-2018, with test conditions of 25~350℃ and a heating / cooling rate of 10℃ / min, using a high-temperature thermal shock furnace (SX2-10).

[0080] The test results are shown in Tables 6 and 7: Table 6 Number of thermal shock cycles in the example ; Table 7 Comparative thermal shock cycle count (times) ; Tables 6 and 7 show that the sample from the examples significantly outperformed the comparative group in terms of the number of thermal shock cycles. This indicates that by optimizing the stabilizer ratio, grain boundary modifier dosage, and surface coating design, the substrate can better alleviate thermal stress concentration and inhibit crack propagation under high-temperature rapid cooling conditions. In particular, Example 5 achieved the highest number of thermal shock cycles (30), demonstrating the best thermal shock resistance among all samples. The comparative examples, lacking a coating or having an unreasonable grain boundary modifier ratio, resulted in a significant decrease in thermal shock resistance.

[0081] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A zirconia ceramic matrix with high thermal shock resistance, characterized in that, The zirconia ceramic matrix includes a matrix and a coating layer a; The matrix comprises the following components: Zirconia 90-98 wt.%; stabilizer 1.5-8 wt.%; grain boundary modifier 0.05-2 wt.%; The stabilizer is 2.0–4.0 wt.% Sc2O3, 0.5–1.5 wt.% Yb2O3, and 0.3–1.0 wt.% Er2O3; The grain boundary regulator is a combination of a boron source and an aluminum source; The preparation method of the coating layer a includes the following steps: Zirconia, aluminum source, phosphorus source and component 1 are added to a solvent and dispersed by stirring or ultrasonication to prepare the coating solution; In the coating layer a, the molar ratio of zirconium to aluminum is (2~3):1; Component 1 is polyvinyl alcohol or polyvinylpyrrolidone.

2. The zirconia ceramic matrix according to claim 1, characterized in that, The coating layer has a double-layer coating structure, including an inner coating layer and an outer coating layer; The method for preparing the outer coating layer includes the following steps: 10-30 wt.% Ti3AlC2 and 0.1-2 wt.% component 1 are added to a solvent and dispersed by stirring or ultrasonication to prepare the outer coating layer solution; The inner coating layer is coating layer a.

3. The zirconia ceramic matrix according to claim 1, characterized in that, The boron source is boric acid or tetraborate.

4. The zirconia ceramic matrix according to claim 1, characterized in that, The aluminum source is aluminum oxide, aluminum salt, or aluminum alkoxide.

5. The zirconia ceramic matrix according to claim 1, characterized in that, In the grain boundary regulator, the mass ratio of boron source to aluminum source is (1-6):(1-10).

6. The method for preparing the zirconia ceramic matrix according to any one of claims 1 to 5, characterized in that, Includes the following steps: S1: Weigh zirconium oxide and stabilizer according to mass percentage, pre-calcine them, add grain boundary regulator, mix evenly, shape and sinter twice to obtain the matrix; S2: Prepare a coating solution for forming a coating layer; S3: The coating solution is applied to the surface of the zirconia ceramic substrate and then heat-treated to obtain the zirconia ceramic substrate.

7. The preparation method according to claim 6, characterized in that, The molding method described in step S1 is any one of dry pressing, isostatic pressing, or slip casting. The sintering temperature is 1350–1600℃, and the sintering time is 1–4 h.

8. The preparation method according to claim 6, characterized in that, The coating method described in step S3 is any one of dip coating, spin coating, or spray coating.

9. The preparation method according to claim 6, characterized in that, The heat treatment in step S3 is performed at a temperature of 600–1300°C for a time of 0.5–6 h.

10. The use of the zirconia ceramic matrix according to any one of claims 1 to 5 in the preparation of composite ceramic materials.