High-strength and high-toughness nano-zirconia ceramic material and preparation method and application thereof

Abstract

The application relates to the technical field of ceramic material preparation, in particular to a high-strength and high-toughness nano-zirconia ceramic material and a preparation method and application thereof. The preparation method of the nano-zirconia ceramic material provided by the application comprises the following steps: taking zirconia powder particles with an amorphous oxide film on the surface as raw materials, and performing forming and sintering treatment. The application firstly proposes to construct a functional gradient film layer on the surface of the zirconia powder particles by using an ALD technology, the obtained film is recrystallized in the subsequent forming and sintering process, oxide grains with nanometer and submicron sizes are formed and distributed in the zirconia grains and the grain boundaries, so that the purposes of strengthening and toughening are achieved; meanwhile, the obtained material has a nano-phase structure, and the biological activity is significantly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ceramic material preparation, in particular to a high-strength and high-toughness nano-zirconia ceramic material and a preparation method and application thereof. BACKGROUND

[0002] Zirconia ceramic material is a commonly used repair material in today's dentistry and orthopedics due to its good mechanical properties, aesthetic properties and biocompatibility, such as zirconia crown, zirconia implant, zirconia joint head, etc.

[0003] However, due to the brittle characteristics of zirconia ceramic material, a certain thickness and size are still required in actual use to ensure sufficient strength and toughness, so as to avoid the occurrence of clinical complications or the limitation of clinical use, and improve the use reliability. For example, the minimum thickness of zirconia crown needs to be greater than 0.5mm, and the area of the connecting part of zirconia bridge needs to be greater than 9mm 2 ; and the zirconia implant itself is more prone to breakage, especially small-diameter zirconia implants (such as 3.3mm in diameter).

[0004] Existing research shows that the structure defects of ceramic material can be reduced and the zirconia grain growth can be inhibited by increasing the ceramic sintering temperature, hot isostatic pressing or specific oxide doping, so as to increase the strength and reliability of the ceramic material. However, for zirconia ceramic material, the above-mentioned methods do not have ideal improvement effect. SUMMARY

[0005] In view of the above problems, the present application provides a new zirconia ceramic material and a preparation method and application thereof. The zirconia ceramic material is nano-sized and has high strength, toughness, biological activity and osteogenic activity.

[0006] In a first aspect, the present application provides a preparation method of nano-zirconia ceramic material, which comprises: using zirconia powder particles with amorphous oxide film on the surface as raw material, and performing forming and sintering treatment.

[0007] The present application first proposes to use zirconia powder particles with amorphous oxide film on the surface as raw material for the preparation of zirconia ceramic material. The amorphous oxide film can recrystallize during the forming and sintering process to form oxide grains (such as aluminum oxide) with nano and sub-micron size distributed in the zirconia grains and the grain boundaries, thereby achieving the purpose of strengthening and toughening, and solving the problem of large brittleness of existing zirconia ceramic material.

[0008] Meanwhile, due to the existence of nanometer-sized oxide grains, the obtained zirconia ceramic material has a nano-phase structure, which not only increases the adhesion of osteoblasts, but also increases the synthesis of alkaline phosphatase of osteoblasts and promotes the deposition of minerals, improves the degree and speed of cell adhesion, and significantly improves the biological activity of the zirconia ceramic material.

[0009] In addition, compared with the prior art of adding nanoparticles to the zirconia ceramic powder raw material to improve the biological activity of the ceramic material, the present application can avoid the grain growth phenomenon of the nanoparticles in the sintering process through the recrystallization of the amorphous oxide film, and ensure the formation of the nano-phase structure of the ceramic material.

[0010] Further, the amorphous oxide film has the following characteristics: the thickness is 0.1 nm-100 nm; the material is binary, ternary or multi-element; and the film layer is a single layer or a functional gradient coating with a thickness-adjustable binary, ternary or multi-element material.

[0011] The material of the amorphous oxide film includes but is not limited to titanium oxide, magnesium oxide, silicon oxide, aluminum oxide, copper oxide, tantalum oxide, zinc oxide, tin oxide, lanthanum oxide and zirconium oxide, etc.

[0012] Research shows that by combining different film layer materials and controlling the thickness, the bonding strength of the film layer can be improved, thereby avoiding the occurrence of peeling, cracking and other situations in subsequent forming and sintering, improving the quality of the oxide grains, and thus improving the strength and toughness of the zirconia ceramic material; at the same time, through the time sequence release of different element components, different biological effects can be played, further providing the biological activity of the zirconia ceramic material.

[0013] For example, taking the aluminum oxide precursor as an example, after 5, 10, 20, 30, 40 and 50 cycles, zirconia powder and zirconia ceramic material with different thicknesses and strengths are obtained, as shown in Figure 5 、 Figure 9 、 Figure 10 Under the condition of the same thickness, the zirconia ceramic material prepared by the present application has a strength improvement of more than 30% and a toughness improvement of 1.5 times compared with the zirconia material (3T-TZP) currently used in clinical practice, and can significantly reduce the thickness when applied to crown preparation.

[0014] Further, the operation conditions of the forming and sintering process of the present application can be adjusted according to the film layer material and thickness of the amorphous oxide film to control its crystallinity, so as to realize the time sequence and precise control of the biological effects of different nanometer films, solve the problem that the current direct atomic layer deposition technology only focuses on deposition itself and ignores biological effects, and thus obtain a ceramic functional preparation technology with strong practicability, high strength and toughness, and better biological activity.

[0015] The forming is dry-press forming, wet forming or additive manufacturing forming. Preferably, the dry-press forming pressure is 130-200 MPa; the wet forming includes slip casting, injection molding and the like.

[0016] The sintering temperature is 1200-1550℃.

[0017] By reasonably controlling the forming and sintering conditions, oxide grains (such as alumina) with nanometer and sub-micron sizes are formed in the crystal grains and at the grain boundaries, the formed oxide grains (such as alumina) are in crystal or nanocrystalline form, thereby significantly improving the strength, toughness and bioactivity, osteogenic activity of the ceramic material.

[0018] Further, based on different amorphous oxide thin films, the corresponding forming and sintering process conditions are also different, and the formed oxide grains also exhibit different strength, toughness and bioactivity.

[0019] As one of the specific embodiments of the present application, zirconia powder particles with an amorphous alumina thin film on the surface are used as raw materials for forming and sintering treatment; the forming and sintering treatment conditions are: first dry-press forming, the pressure is 160-200 MPa, and then sintering at a temperature of 1300℃-1550℃ at a speed of 10-30℃ / min for 2h.

[0020] Further, the amorphous oxide thin film is formed on the surface of the zirconia powder particles by atomic layer deposition technology. Moreover, the material and thickness of each film layer in the functional gradient coating can be adjusted by adjusting the type of precursor, deposition sequence and cycle number.

[0021] As one of the specific embodiments of the present application, a method for preparing a nano-zirconia ceramic material by ALD technology is provided, and the reaction principle is shown in Figure 1 The method comprises the following steps:

[0022] (1) The first surface reaction of the reaction site of trimethylaluminum precursor A and zirconia powder particles is carried out;

[0023] The operation conditions are as follows: the dried zirconia powder material is placed in the cavity of the atomic layer deposition device filled with inert gas, the temperature is raised, and the reaction cavity temperature is maintained at 200-350℃, after reaching the temperature, the reaction cavity is vacuumized for 1 -10 s;

[0024] Nitrogen is used as the carrier, trimethylaluminum is introduced into the cavity, and the reaction time is controlled to be 0.1 -10 s;

[0025] (2) inert gas is introduced into the cavity to remove unreacted precursor A and volatile by-product hydrogen chloride in the reaction cavity;

[0026] (3) the precursor B water is subjected to a second surface reaction with the reaction sites after the surface reaction in step (1), and at this time the surface of the zirconia powder particles is converted back to the starting surface with the same reaction sites;

[0027] The operating conditions are as follows: nitrogen is used as the carrier, H2O is introduced into the cavity, and the reaction time is controlled to be 0.01 -20 s;

[0028] (4) the inert gas is used again to sweep to obtain an amorphous aluminum oxide film, and a cycle is completed;

[0029] (5) the steps (1)-(4) are repeated until the thickness of the amorphous aluminum oxide film reaches the target thickness;

[0030] (6) the zirconia powder particles with the amorphous aluminum oxide film obtained in step (5) are subjected to molding and sintering treatment;

[0031] The molding and sintering treatment conditions are as follows: the molding conditions can be dry pressing molding: the pressure is 160-200 MPa, or wet molding (such as slip casting), or additive manufacturing molding, and the final sintering temperature is 1450-1550 DEG C.

[0032] In the second aspect, the application provides a nano-zirconia ceramic material obtained by the above preparation method.

[0033] The nano-zirconia ceramic material comprises zirconia grains and oxide grains distributed in the zirconia grains and the grain boundaries; the average particle size of the zirconia grains is ≤1 μm; the average particle size of the oxide grains is ≤500 nm; and as the content of the oxide grains increases, the average grain size of the zirconia grains decreases; the oxide grains with an average particle size of ≤200 nm exist in the zirconia grains; and the crystal form of the oxide grains is crystal or nanocrystal. Compared with conventional zirconia ceramic materials, the nano-zirconia ceramic material has higher strength, toughness and better biological activity.

[0034] In the third aspect, the application provides a ceramic restoration material containing the above nano-zirconia ceramic material.

[0035] Compared with conventional zirconia ceramic materials, the ceramic restoration material has better strength and toughness, good aesthetic performance and biocompatibility.

[0036] The technical scheme of the application has the following beneficial effects:

[0037] (1) The application firstly proposes to apply atomic layer deposition technology to the preparation technology of zirconia ceramic material. By plating amorphous oxide film on the surface of zirconia powder particles in the form of single atom film layer by layer, the oxide grains (such as aluminum oxide) with nanometer size are formed in the zirconia grains and the grain boundaries in the subsequent forming and sintering process, and the oxide grain crystal form is crystal or nanocrystal, so as to realize the purpose of strengthening and toughening, and solve the problem of large brittleness of the existing zirconia ceramic material.

[0038] (2) The zirconia ceramic material obtained by the application has a nano-phase structure, which not only increases the adhesion of osteoblasts, but also increases the synthesis of alkaline phosphatase of osteoblasts and promotes the deposition of minerals, improves the degree and speed of cell adhesion, and significantly improves the biological activity of the zirconia ceramic material.

[0039] (3) The application controls the atomic composition and thickness of each layer of the amorphous oxide film in the atomic layer deposition process by adjusting the type of precursor, deposition sequence and cycle number, so as to improve the binding strength of each film layer, and further avoid the occurrence of falling off, cracking and other situations in the subsequent forming and sintering, improve the quality of the oxide grain, and thus improve the strength and toughness of the zirconia ceramic material; at the same time, through the time sequence release of different element components, different biological effects can be played, and the biological activity of the zirconia ceramic material is further provided.

[0040] (4) The preparation method has the advantages of relatively simple process, easy to control, and suitable for large-scale industrial production. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 Reaction principle diagram for the preparation process of the nano-zirconia ceramic material described in Example 1.

[0042] Figure 2 TEM results of zirconia powder particles obtained by different cycle numbers; wherein, control is untreated zirconia powder; 10 cycles is 10 cycles (10 nm); 30 cycles is 30 cycles (10 nm); 50 cycles is 50 cycles (10 nm).

[0043] Figure 3 FFT crystal analysis results of the body and surface deposition coating of the 50-cycle zirconia powder particles, respectively.

[0044] Figure 4 XRD results of zirconia powder particles and nano-zirconia ceramic material obtained by different cycle numbers; wherein, (a) is zirconia powder particles; (b) is nano-zirconia ceramic material obtained by pressing and sintering.

[0045] Figure 5 Electron microscopy (EM) images and surface distribution diagrams of nano-zirconia ceramic materials containing alumina grains after different number of cycles are shown. (a) represents 5 cycles (1 μm), and the right image shows the aluminum element distribution in the zirconia grains. (b) represents 10 cycles (400 nm). (c) represents 20 cycles (400 nm). (d) represents 30 cycles (400 nm). (e) represents 40 cycles (400 nm). (f) represents 50 cycles (400 nm). (g) represents the untreated group (400 nm). (h) shows the measurement and analysis results of the zirconia grain size in each group.

[0046] Figure 6 Electron micrograph of nano-zirconia ceramic material containing alumina grains after 30 cycles; arrows of different gray levels indicate different distribution patterns of the doped alumina particles.

[0047] Figure 7 The images show the TEM observation results after FIB sectioning of nano-zirconia ceramic material containing alumina grains for 50 cycles; (a) shows the alumina grains containing nano-zirconia grains; (b) shows the zirconia grains containing nano-alumina grains.

[0048] Figure 8 The results of aperture-selective diffraction of alumina particles in TEM.

[0049] Figure 9 A comparison of the strength of different zirconia ceramic materials.

[0050] Figure 10 A comparison of the toughness of different zirconia ceramic materials.

[0051] Figure 11 Comparison of osteogenic properties of different zirconia ceramic materials.

[0052] Figure 12 Comparison of osteogenic-related gene expression results for different zirconia ceramic materials; among them, Runx2 is Runt-related transcription factor-2; BMP2 is bone morphogenetic protein-2. Detailed Implementation

[0053] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the invention.

[0054] Example 1

[0055] This embodiment provides a method for preparing nano-zirconia ceramic materials, taking ALD alumina as an example. The reaction process and principle are as follows: Figure 1 As shown, the overall reaction equation is as follows:

[0056] 2 Al(CH3)3(g) + 3 H2O(g) → Al203+ 6 CH4(g)↑

[0057] First step:

[0058] Al(CH3)3(g) + Zr(OH)(s) → Zr-O-Al(CH3)2(s) + CH4(g)↑

[0059] Second step:

[0060] Zr-O-Al(CH3)2(s) + 2 H-OH(g) → Zr-O-Al(OH)2(s) + 2 CH4(g)↑

[0061] The specific steps are as follows:

[0062] S1, formation of amorphous aluminum oxide film

[0063] (1) Introduce precursor A trimethylaluminum into the reaction bottle to react with the reaction sites on the zirconia powder particles;

[0064] The operation is as follows: the dried positive electrode material is placed in the cavity of the atomic layer deposition device filled with inert gas, the temperature is raised, and the reaction chamber temperature is kept at 180°C, after reaching the temperature, the reaction cavity is vacuumed for 10s;

[0065] Trimethylaluminum is introduced into the cavity with nitrogen as the carrier, and the reaction time is controlled for 1s;

[0066] (2) Purge with inert gas to remove unreacted precursors and volatile byproducts hydrogen chloride in the reaction cavity;

[0067] (3) Introduce precursor B water into the reaction cavity for the second reaction, at which time the surface of the zirconia powder particles is converted back to the starting surface with the same reaction sites;

[0068] The operation conditions are as follows: H2O is introduced into the cavity with nitrogen as the carrier, and the reaction time is controlled for 0.5s;

[0069] (4) Purge with inert gas again to obtain an amorphous aluminum oxide film, completing a cycle;

[0070] (5) Repeat steps (1)-(4) above until the thickness of the amorphous aluminum oxide film reaches the target thickness;

[0071] S2, forming and sintering treatment:

[0072] (6) Forming and sintering treatment is performed on the zirconia powder particles with amorphous aluminum oxide film obtained in step (5);

[0073] Molding methods and operating conditions: Dry pressing, with a pressure of 160-200MPa; or wet molding (such as injection molding); or additive manufacturing, etc.

[0074] Sintering conditions: Sintering temperature is 1450-1550℃.

[0075] The results show:

[0076] (1) As Figure 2 As shown, in the powder transmission electron microscopy (TEM) results after deposition, the powder particles of different cycles of ALD are uniformly coated with coatings of different thicknesses, and the coating thickness increases with the number of cycles.

[0077] (2) Figure 3 As shown, selected area Fourier transform (FFT) analysis was performed on the powder particle body and the surface coating. The results showed that the zirconium oxide particle body is crystalline and the surface coating is amorphous.

[0078] (3) Figure 4 As shown in the X-ray diffraction (XRD) results, no obvious alumina component was detected in the powders with different ALD cycle numbers. However, after isostatic pressing and sintering, trace amounts of alumina component were detected in the zirconia sheets of each group of zirconia powders. This indicates that the ALD method successfully deposited an amorphous, non-crystalline alumina layer on the surface of zirconia powder particles, and the thickness of this layer can be calculated from the cycle number to be sub-nanometer.

[0079] (4) Figure 5 As shown, scanning electron microscopy (SEM) and surface mapping results demonstrate that the alumina particle content increases with increasing deposition thickness after sintering. Furthermore, compared with zirconia produced by sintering untreated zirconia powder, the zirconia grain size of ALD alumina on the powder particle surface is significantly reduced, indicating that alumina is uniformly present between zirconia grains, thus limiting the growth of zirconia grains.

[0080] (5) Figure 6 As shown, the sintered alumina grains have different distribution patterns in zirconia. Some are distributed at the junction of zirconia grains and are surrounded by 4 to 5 zirconia grains; some are distributed on the junction line of two zirconia grains; and some are completely wrapped by zirconia grains.

[0081] (6) Figure 7 As shown, high-resolution transmission electron microscopy (FIB-TEM) was performed on the prepared sections using focused ion beam, revealing that nano-sized alumina particles are encapsulated within the zirconia grains; nano-sized zirconia particles are also encapsulated within the alumina grains.

[0082] (7) Figure 8The results show that the alumina grains contain a large number of nanocrystals.

[0083] (8) As Figure 9 The results show that the flexural strength of the zirconia pieces of the ALD alumina group increased by 30% compared to 3 mol% yttrium-stabilized zirconia (3Y-TZP) and by 10% compared to cerium-stabilized zirconia (Ce-TZP), calculated according to the method for testing the strength of ceramic materials by double-bending strength according to ISO 6872:2008.

[0084] (9) As Figure 10 The results show that the fracture toughness of the zirconia pieces of the ALD alumina group increased by about 150% compared to 3 mol% yttrium-stabilized zirconia (3Y-TZP) and by 37% compared to cerium-stabilized zirconia (Ce-TZP), calculated according to the method for testing the strength of ceramic materials by double-bending strength according to ISO 6872:2008.

[0085] (10) Biological activity: As Figure 11 The results show that the nano-zirconia pieces of the ALD alumina group increased the expression of alkaline phosphatase of the osteoblasts (MC3T3-e1), indicating better osteogenic performance.

[0086] (11) As Figure 12 The results show that the expression of the osteogenic-related gene markers RUNX2 and BMP2 in the MC3T3-e1 cells cultured on the surface of the zirconia pieces of the ALD alumina group was significantly higher than that of 3Y-TZP, Ce-TZP and the nano-zirconia product NANOZR, indicating that it has better osteogenic performance.

[0087] Although the present application has been described in detail above with general description and specific embodiments, some modifications or improvements can be made on the basis of the present application, which is obvious to those skilled in the art. Therefore, these modifications or improvements made on the basis of not deviating from the spirit of the present application, all belong to the scope of the present application claimed.

Claims

1. A method for preparing nano-zirconia ceramic material, characterized in that, Includes the following steps: (1) The precursor A trimethylaluminum reacts with the reaction sites of zirconium oxide powder particles for the first surface reaction; the operating conditions are as follows: the dried zirconium oxide powder material is placed in the cavity of an atomic layer deposition equipment filled with inert gas, the temperature is raised and the temperature of the reaction cavity is maintained between 200-350℃, and after the temperature is reached, the reaction cavity is evacuated for 1-10s; trimethylaluminum is introduced into the cavity using nitrogen as a carrier, and the reaction time is controlled to be 0.1-10s; (2) Purge the chamber with inert gas to remove unreacted precursor A and volatile byproduct hydrogen chloride from the reaction chamber; (3) The precursor B water is reacted with the sites after the surface reaction in step (1) for a second surface reaction. At this time, the surface of the zirconium oxide powder particles is converted back to the starting surface with the same reaction sites. The operating conditions are as follows: using nitrogen as a carrier, H2O is introduced into the cavity, and the reaction time is controlled to be 0.01-20s; (4) Purge again with inert gas to obtain an amorphous aluminum oxide film, completing one cycle; (5) Repeat steps (1)-(4) above until the thickness of the amorphous alumina film reaches the target thickness; (6) The zirconium oxide powder particles with amorphous alumina film obtained in step (5) are subjected to molding and sintering treatment; The nano-zirconia ceramic material includes zirconia grains and alumina grains of nano and submicron size distributed within and at the grain boundaries of the zirconia grains. The average grain size of the zirconium oxide grains is ≤1μm; The average grain size of the alumina crystals is ≤500nm; Furthermore, as the alumina grain content increases, the average grain size of the zirconia grains decreases accordingly. Furthermore, alumina grains with an average particle size ≤200nm exist within the zirconium oxide grains.

2. The method for preparing nano-zirconia ceramic material according to claim 1, characterized in that, The amorphous alumina film has the following characteristics: its thickness is 0.1nm-100nm.

3. A nano-zirconia ceramic material, characterized in that, Obtained by the preparation method described in claim 1 or 2.

4. A ceramic repair material, characterized in that, Contains the nano-zirconia ceramic material as described in claim 3.

Images