High-toughness lithium disilicate glass-ceramic composite material, preparation method and application thereof

Abstract

The application belongs to the technical field of preparing microcrystalline glass materials, and particularly relates to a high-toughness lithium disilicate microcrystalline glass composite material, a preparation method thereof and application thereof. The method comprises the following steps: (1) preparing lithium disilicate glass micro powder; (2) immersing alumina fibers in a silica sol, and then taking out the alumina fibers and sintering the alumina fibers at 900-1100 DEG C, so that a silica film is formed on the surface of the alumina fibers; (3) mixing the product obtained in the step (2) with the lithium disilicate glass micro powder to obtain a mixture; (4) sintering the mixture to form an intermediate block, and then sintering the intermediate block at 790-860 DEG C and under a pressure of 15-45 MPa. The fracture toughness of the lithium disilicate microcrystalline glass composite material prepared by the method can reach 4.3 MPa·m 1 / 2 The above value is far higher than the current commercial lithium disilicate microcrystalline glass material of 3.0 MPa·m 1 / 2 , and can significantly improve the performance of the lithium disilicate microcrystalline glass.

Description

Technical Field

[0001] This invention belongs to the field of microcrystalline glass material preparation technology, specifically relating to a high-toughness lithium disilicate microcrystalline glass composite material, its preparation method, and its application. Background Technology

[0002] Brittleness is a common weakness of ceramics and glass materials, manifested as sudden, explosive fracture under applied load. Fracture toughness is generally used to characterize the degree of brittleness in materials; the greater the fracture toughness, the greater the critical stress required for crack instability and propagation, and the less brittle the material. Lithium disilicate (Li2Si2O5) glass-ceramics are among the toughest glass-ceramic materials and are widely used in dental and bone restoration materials.

[0003] The fracture toughness of currently commercially available lithium disilicate glass-ceramic materials is generally around 3.0 MPa.m. 1 / 2 Around 1.5 MPa·m, higher than that of ordinary oxide glass. 1 / 2 And 1.8 MPa·m of nitride glass 1 / 2 However, compared to alumina ceramics (3-4 MPa·m 1 / 2 ) and zirconia ceramics (8-10 MPa·m 1 / 2 However, the toughness of lithium disilicate glass-ceramics remains significantly lower. Ivoclar's IPS·Empress 2 product is currently a leading international brand of lithium disilicate glass-ceramics, with a fracture toughness of approximately 3.14 MPa·ml / 2. How to further improve the toughness of lithium disilicate glass-ceramics based on existing technology, thereby expanding its application areas and scope, has been a continuous pursuit in the materials science community.

[0004] Current research on toughening lithium disilicate glass-ceramics mainly focuses on methods such as adding nucleating agents and improving heat treatment processes, but the effects are quite limited. Adding reinforcing phases to brittle materials is a common method for achieving material toughening. The introduction of reinforcing phases can help the material resist cracks under external loads by acting as crack pinning, deflection, and bridging agents, thus consuming more energy and significantly improving the material's strength and toughness. However, lithium disilicate glass-ceramics contain a large amount of small-radius Li... + At high temperatures, lithium disilicate readily reacts with the reinforcing phase, causing the reinforcing phase to fail. Therefore, how to effectively improve the fracture toughness of lithium disilicate glass-ceramics, expand its application range, and ensure that the reinforcing phase introduced into lithium disilicate glass-ceramics does not fail are urgent problems to be solved. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the defects such as the difficulty in improving the toughness of lithium disilicate glass-ceramics and the easy failure of the reinforcing phase at high temperature when using composite material process for toughening, so as to provide a high-toughness lithium disilicate glass-ceramic composite material, its preparation method and application.

[0006] To this end, the present invention provides the following technical solution.

[0007] This invention provides a method for preparing a high-toughness lithium disilicate microcrystalline glass composite material, comprising the following steps:

[0008] (1) Preparation of lithium disilicate glass micro powder;

[0009] (2) The alumina fiber is immersed in silica sol and then sintered at 900-1100℃ to form a silica film on the surface of the alumina fiber.

[0010] (3) The product obtained in step (2) is mixed with the lithium disilicate glass micro powder to obtain a mixture;

[0011] (4) The mixture is first fired to form an intermediate block, and then fired a second time at 790-860℃ and 15-45MPa.

[0012] The diameter of the alumina fiber is 0.6-2.0 μm.

[0013] The specific steps of the second firing process include: heating to 790-860°C at a heating rate of 5-10°C / min, then pressurizing to 15-45 MPa and firing for 1-3 hours. Further, the second firing is carried out in a hot-press sintering furnace.

[0014] The specific steps of step (2) and the sintering process include: heating to 900-1100℃ at a heating rate of 5-15℃ / min and holding at that temperature for 10-30 minutes.

[0015] The first firing step includes: heating to 690-760℃ at a heating rate of 2-10℃ / min and holding at that temperature for 1-2 hours;

[0016] Preferably, a shaping step is included before the first firing. There are no special requirements for shaping; the mixture is formed into a block shape that meets the shape and size requirements, thus obtaining an intermediate block.

[0017] In step (3), the mass ratio of the product of step (2) to the lithium disilicate glass powder is 1:5-1:9.

[0018] In step (3), the product obtained in step (2) is mixed with the lithium disilicate glass micro powder and then further ball-milled.

[0019] Preferably, the ball milling time is 1-3 hours.

[0020] The soaking time in step (2) is 0.5-2.0 hours;

[0021] Preferably, the particle size of the lithium disilicate glass micropowder is 30-70 μm.

[0022] In this invention, the main components of lithium disilicate glass micropowder include SiO2, Li2O, K2O, P2O5, Al2O3, etc., with some oxides introduced as raw materials from carbonates or high-purity minerals. The raw materials are mixed according to the composition ratio of the lithium disilicate glass micropowder, passed through an 80-mesh sieve, melted at high temperature and held at that temperature for 2 hours, then quenched in water, crushed, ground, and sieved. Specifically, the high-temperature melting temperature is not specifically required, as long as it is sufficient to melt the raw materials and achieve complete homogenization and clarification. Additionally, ZrO2, GeO2, etc., can be added to the lithium disilicate glass micropowder according to usage requirements. Lithium disilicate glass micro powder comprises SiO2, Li2O, K2O, P2O5, and Al2O3 in a mass ratio of (62-66):(9-15):(5-6):(4-5):(1-2); further, lithium disilicate glass micro powder may also comprise SiO2, Li2O, K2O, P2O5, Al2O3, ZrO2, and GeO2 in a mass ratio of (62-66):(9-15):(5-6):(4-5):(1-2):(5-11):(1-2).

[0023] The present invention also provides a lithium disilicate microcrystalline glass composite material prepared by the above preparation method.

[0024] Furthermore, the present invention also provides an application of the lithium disilicate microcrystalline glass composite material prepared by the above preparation method as a dental material, bone material, communication tool backplate material or precision ceramic component material.

[0025] The technical solution of this invention has the following advantages:

[0026] 1. The present invention provides a method for preparing a high-toughness lithium disilicate microcrystalline glass composite material, comprising: (1) preparing lithium disilicate glass micropowder; (2) immersing alumina fibers in silica sol, removing them, and sintering them at 900-1100℃ to form a silica film on the surface of the alumina fibers; (3) mixing the product obtained in step (2) with the lithium disilicate glass micropowder to obtain a mixture; (4) after a first firing, the mixture forms an intermediate block, which is then subjected to a second firing at 790-860℃ and 15-45MPa. The fracture toughness of the lithium disilicate microcrystalline glass composite material prepared by this method can reach 4.3MPa·m. 1 / 2The above figures far exceed the 3.0 MPa·m of currently commercially available lithium disilicate microcrystalline glass materials. 1 / 2 This significantly reduces the brittleness of the material, which can substantially improve the performance of lithium disilicate glass-ceramics and expand its application range.

[0027] Furthermore, this invention overcomes the problem in existing technologies where alumina fibers, as reinforcing phases, readily react with the large amount of small-radius Li₂ in lithium disilicate glass when applied as reinforcing fibers. + This invention addresses the problem of reinforcing phase failure caused by reactions, and fully utilizes the reinforcing properties of alumina fibers. Specifically, the present invention forms a dense silicon oxide film by impregnating alumina fibers in silica sol and sintering at 900-1100°C, which hinders the Li in the lithium disilicate matrix phase from reacting. + To address the issue of diffusion-induced fiber deformation, calcination at 900-1100℃ ensures that the silica on the fiber surface forms a liquid phase, tightly bonding with the fiber. Furthermore, it prevents excessively high temperatures from causing the silica layer and alumina to react and form a mullite crystalline phase, thus ensuring the strengthening and toughening effect of the alumina fibers. The initial calcination to form a bulk material allows for a second calcination under specific pressure and temperature. Simultaneously, it allows the residual glass phase in the lithium disilicate glass-ceramic to acquire a certain degree of plasticity under pressure, achieving the preparation of a highly dense sintered body, which is beneficial for improving the toughness of the composite material.

[0028] Furthermore, alumina fibers possess a tensile strength as high as 2600 MPa. Since lithium disilicate glass-ceramics contain both alumina and silicon dioxide, using alumina fibers with a silicon dioxide film on their surface as a reinforcing phase can improve the wettability between the reinforcing phase and the disilicate glass-ceramics at the interface, facilitating the formation of a good interface. In addition, alumina, as a reinforcing phase, has a coefficient of thermal expansion of 7.0 × 10⁻⁶. -6 ℃ -1 Around 1000 ppm, while the thermal expansion coefficient of lithium disilicate glass is 7.9 × 10⁻⁶ ppm. -6 ℃ -1 The coefficient of thermal expansion of lithium disilicate glass is slightly higher than that of alumina. Therefore, during the firing and cooling process, lithium disilicate glass shrinks relatively more, which creates compressive stress on the alumina fibers. This helps to suppress the formation and propagation of cracks at the interface between the fiber-reinforced phase and the lithium disilicate glass matrix.

[0029] 2. The preparation method of the high-toughness lithium disilicate glass-ceramic composite material provided by this invention limits the diameter of the alumina fibers to the range of 0.6-2.0 μm. This is because the size of lithium disilicate crystals in the matrix phase is generally 1-3 μm. Selecting alumina fibers slightly smaller than the size of lithium disilicate crystals is beneficial because they exist as a reinforcing phase at grain boundaries rather than replacing the positions of the lithium disilicate crystals themselves, thus not affecting the microstructure of the interlocking of the lithium disilicate microcrystals. Furthermore, during the ball milling process, the alumina fibers with a dense silica film can be fully and uniformly mixed with the lithium disilicate glass powder, while excessively long fibers can be shortened, resulting in more uniform mixing with the lithium disilicate glass powder.

[0030] 3. The preparation method of the high-toughness lithium disilicate glass-ceramic composite material provided by the present invention involves mixing modified alumina fibers and lithium disilicate glass powder at a mass ratio of 1:5 to 1:9, which can ensure the pull-out effect and load transfer capacity of alumina fibers, and will not affect the gloss, color, biocompatibility and other properties of the lithium disilicate glass-ceramic itself. Detailed Implementation

[0031] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0032] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0033] Example 1

[0034] This embodiment provides a method for preparing a high-toughness lithium disilicate microcrystalline glass composite material, including the following steps:

[0035] (1) Preparation of lithium disilicate glass micro powder

[0036] The mass composition of the oxides in the lithium disilicate glass micropowder is as follows: SiO2 66%, Li2O 9%, ZrO2 11%, K2O 6%, P2O5 5%, Al2O3 2%, and GeO2 1%. Li2O and K2O are introduced in the form of lithium carbonate and potassium carbonate, respectively, while P2O5 is introduced in the form of diammonium hydrogen phosphate. According to the specified ratio, the components are mixed evenly and passed through an 80-mesh standard sieve. The mixture is then melted at 1450℃ and held at this temperature for 2 hours to promote the clarification and homogenization of the glass melt. The fully clarified and homogenized glass melt is then directly poured into clean water for water quenching, crushing, grinding, and sieving to obtain lithium disilicate glass micropowder with a diameter of 30-50 μm.

[0037] (2) Alumina fibers with a diameter of 1.5-2.0 μm are impregnated in silica sol for 0.5 h. After impregnation, the fibers are removed and the excess sol on the fibers is removed by centrifugation. Then, the fibers are heated to 1000 °C at a heating rate of 5 °C / min and kept at 1000 °C for 20 min to form a dense silica film on the surface of the alumina fibers, thus obtaining the modified fibers.

[0038] (3) The modified fiber obtained in step (2) and the lithium disilicate glass micro powder obtained in step (1) are mixed in a mass ratio of 1:6, water is added and the mixture is ball-milled for 2 hours and then dried to obtain a mixture.

[0039] (4) The mixture is molded into an intermediate block, heated to 730°C at a heating rate of 3°C / min and held for 2 hours for the first firing, and then cooled with the furnace to obtain the intermediate block; then it is placed in a hot press sintering furnace for the second firing, heated to 860°C at a heating rate of 10°C / min, then pressurized to 35MPa and fired for 2 hours, then the pressure is removed and cooled with the furnace to obtain the composite material.

[0040] Strength tests were conducted according to the method specified in GB / T4740-1999, and the flexural strength of the composite material obtained in this embodiment was 563 MPa. Toughness tests were conducted according to the method specified in GB / T23806-2009, and the fracture toughness of the composite material obtained in this embodiment was 4.53 MPa·m. 1 / 2 .

[0041] Example 2

[0042] This embodiment provides a method for preparing a high-toughness lithium disilicate microcrystalline glass composite material, including the following steps:

[0043] (1) Prepare lithium disilicate glass micro powder. Based on the method in Example 1, adjust the sieving parameters to obtain lithium disilicate glass micro powder with a diameter of 50-70 μm.

[0044] (2) Alumina fibers with a diameter of 0.6-1.2 μm are impregnated in silica sol for 1.0 h. After impregnation, the fibers are removed and the excess sol on the fibers is removed by centrifugation. The fibers are then heated to 900 °C at a heating rate of 10 °C / min and kept at that temperature for 30 min to form a dense silica film on the surface of the alumina fibers, thus obtaining the modified fibers.

[0045] (3) The modified fiber obtained in step (2) and the lithium disilicate glass micro powder obtained in step (1) are mixed in a mass ratio of 1:9, water is added and the mixture is ball-milled for 1.5 hours and then dried to obtain a mixture.

[0046] (4) The mixture is molded to obtain an intermediate block, heated to 750°C at a heating rate of 6°C / min and held for 1 hour for the first firing, and then cooled with the furnace to obtain the intermediate block; then it is placed in a hot press sintering furnace for the second firing, heated to 820°C at a heating rate of 7°C / min, then pressurized to 15MPa and fired for 3 hours, the pressure is removed, and the composite material is obtained after cooling with the furnace.

[0047] Strength tests were conducted according to the method specified in GB / T4740-1999, and the flexural strength of the composite material obtained in this embodiment was 549 MPa. Toughness tests were conducted according to the method specified in GB / T23806-2009, and the fracture toughness of the composite material obtained in this embodiment was 4.36 MPa·m. 1 / 2 .

[0048] Example 3

[0049] This embodiment provides a method for preparing a high-toughness lithium disilicate microcrystalline glass composite material, including the following steps:

[0050] (1) Prepare lithium disilicate glass micro powder. Based on the method in Example 1, adjust the sieving parameters to obtain lithium disilicate glass micro powder with a diameter of 40-60 μm.

[0051] (2) Alumina fibers with a diameter of 1.0-1.5 μm are impregnated in silica sol for 2.0 h. After impregnation, the fibers are removed and the excess sol on the fibers is removed by centrifugation. The temperature is then raised to 1100℃ at a rate of 15℃ / min and held for 10 min to form a dense silica film on the surface of the alumina fibers, thus obtaining the modified fibers.

[0052] (3) The modified fiber obtained in step (2) and the lithium disilicate glass micro powder obtained in step (1) are mixed in a mass ratio of 1:5, water is added and the mixture is ball-milled for 3.0 h, and then dried to obtain a mixture.

[0053] (4) The mixture is molded to obtain an intermediate block. It is heated to 690°C at a heating rate of 2°C / min and held for 1.5h for the first firing. Then it is cooled with the furnace to obtain the intermediate block. It is then placed in a hot press sintering furnace for the second firing. It is heated to 790°C at a heating rate of 5°C / min. Then it is pressurized to 45MPa and fired for 1.5h. The pressure is removed and it is cooled with the furnace to obtain the composite material.

[0054] Strength tests were conducted according to the method specified in GB / T4740-1999, and the flexural strength of the composite material obtained in this embodiment was 623 MPa. Toughness tests were conducted according to the method specified in GB / T23806-2009, and the fracture toughness of the composite material obtained in this embodiment was 4.75 MPa·m. 1 / 2 .

[0055] Comparative Example 1

[0056] This comparative example provides a method for preparing a composite material, including the following steps:

[0057] (1) Prepare lithium disilicate glass micro powder. Lithium disilicate glass micro powder with a diameter of 30-50 μm was prepared according to the method in Example 1.

[0058] (2) Alumina fibers with a diameter of 1.5-2.0 μm are mixed with lithium disilicate glass micro powder obtained in step (1) at a mass ratio of 1:6, water is added and ball milled for 2 hours, and then dried to obtain a mixture.

[0059] (3) The mixture is molded into an intermediate block, heated to 730°C at a heating rate of 3°C / min and held for 2 hours for the first firing, and then cooled with the furnace; then it is placed in a hot press sintering furnace for the second firing, heated to 860°C at a heating rate of 10°C / min, then pressurized to 35MPa and fired for 2 hours, then the pressure is removed and cooled with the furnace to obtain the composite material.

[0060] The composite material obtained in this comparative example has a flexural strength of 451 MPa and a fracture toughness of 3.86 MPa·m, as tested. 1 / 2 The testing method is the same as in Example 1.

[0061] Comparative Example 2

[0062] This comparative example provides a method for preparing a composite material, including the following steps:

[0063] (1) Prepare lithium disilicate glass micro powder. Lithium disilicate glass micro powder with a diameter of 30-50 μm was prepared according to the method in Example 1.

[0064] (2) Alumina fibers with a diameter of 1.5-2.0 μm were impregnated in silica sol for 0.5 h. After impregnation, the fibers were removed and the excess sol was removed by centrifugation. The temperature was then raised to 1250 °C at a rate of 5 °C / min and held for 20 min. A mullite film layer was formed on the surface of the alumina fibers by silica, and the modified fibers were obtained.

[0065] (3) The modified fiber obtained in step (2) and the lithium disilicate glass micro powder obtained in step (1) are mixed in a mass ratio of 1:6, water is added and the mixture is ball-milled for 2 hours and then dried to obtain a mixture.

[0066] (4) The mixture is molded and heated to 730°C at a heating rate of 3°C / min and held for 2 hours for the first firing. Then it is cooled in the furnace. Then it is placed in a hot press sintering furnace for the second firing. It is heated to 860°C at a heating rate of 10°C / min. Then it is pressurized to 35MPa and fired for 2 hours. After the pressure is removed, it is cooled in the furnace to obtain the composite material.

[0067] The composite material obtained in this comparative example has a flexural strength of 439 MPa and a fracture toughness of 2.79 MPa·m, as tested. 1 / 2 The testing method is the same as in Example 1.

[0068] Comparative Example 3

[0069] This comparative example provides a method for preparing a composite material, including the following steps:

[0070] (1) Prepare Li2O-K2O-P2O5-ZrO2-SiO2 lithium disilicate glass. Lithium disilicate glass micro powder with a diameter of 30-50 μm was prepared according to the method in Example 1.

[0071] (2) Alumina fibers with a diameter of 1.5-2.0 μm are impregnated in silica sol for 0.5 h. After impregnation, the fibers are removed and the excess sol on the fibers is removed by centrifugation. The temperature is then raised to 1000℃ at a rate of 5℃ / min and kept at 20 min to form a silica film on the fiber surface, thus obtaining the modified fiber.

[0072] (3) The modified fiber obtained in step (2) and the lithium disilicate glass micro powder obtained in step (1) are mixed in a mass ratio of 1:6, water is added and the mixture is ball-milled for 2 hours and then dried to obtain a mixture.

[0073] (4) The mixture was molded and heated to 730°C at a heating rate of 3°C / min and held for 2 hours for the first firing. Then it was cooled in the furnace. Then it was placed in a hot press sintering furnace for the second firing. It was heated to 900°C at a heating rate of 10°C / min. Then it was pressurized to 50MPa and fired for 2 hours. After the pressure was removed, it was cooled in the furnace to obtain the composite material. The test method was the same as in Example 1.

[0074] The composite material obtained in this comparative example has a flexural strength of 416 MPa and a fracture toughness of 2.66 MPa·m, as tested. 1 / 2 .

[0075] Analysis of the flexural strength and fracture toughness of the composite materials in the examples and comparative examples shows that, in this invention, alumina fibers are impregnated in silica sol, sintered at 900-1100℃, and a dense silica film is formed on the surface of the alumina fibers. A second sintering is then performed at 790-860℃ and 15-45 MPa. The alumina fibers, as a reinforcing phase, do not react with the Li in the lithium disilicate glass. + The problem of reaction leading to the failure of the reinforcing phase can be addressed by fully utilizing the reinforcing properties of alumina fibers to improve the fracture toughness and flexural strength of lithium disilicate glass.

[0076] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a high-toughness lithium disilicate glass-ceramic composite material, characterized in that, The method comprises the following steps: (1) preparing lithium disilicate glass micro-powder; (2) dipping alumina fibers into silica sol, and sintering at 900-1100 ℃ after taking out, so that silica film is formed on the surface of the alumina fibers; (3) mixing the product obtained in step (2) with the lithium disilicate glass micro-powder to obtain a mixture; (4) forming an intermediate block after first sintering, and then performing second sintering at 790-860 ℃ and 15-45 MPa.

2. The production method according to claim 1, characterized by, The diameter of the alumina fibers is 0.6-2.0 μm.

3. The production method according to claim 1 or 2, characterized by, The specific steps of the second sintering include: heating at a heating rate of 5-10 ℃ / min to 790-860 ℃, and then sintering at 15-45 MPa for 1-3 h.

4. The method of claim 1, wherein, In step (2), the specific steps of the sintering include: heating at a heating rate of 5-15 ℃ / min to 900-1100 ℃, and then keeping the temperature for 10-30 min.

5. The preparation method according to claim 1, characterized in that, The specific steps of the first sintering include: heating at a heating rate of 2-10 ℃ / min to 690-760 ℃, and then keeping the temperature for 1-2 h.

6. The production method according to claim 1 or 5, characterized by, Before the first sintering, a forming step is further included.

7. The preparation method according to claim 1, characterized in that, In step (3), the mass ratio of the product of step (2) to the lithium disilicate glass micro-powder is 1:5-1:

9.

8. The production method according to claim 1 or 7, characterized by, In step (3), after mixing the product of step (2) with the lithium disilicate glass micro-powder, a ball milling step is further included.

9. The production method according to claim 8, characterized by, The ball milling time is 1-3 h.

10. The method of claim 1, wherein, In step (2), the dipping time is 0.5-2.0 h.

11. The preparation method according to claim 8, characterized in that, The particle size of the lithium disilicate glass micro-powder is 30-70 μm.

12. A lithium disilicate glass-ceramic composite material prepared by the method of any one of claims 1-11.

13. Use of the lithium disilicate glass-ceramic composite material prepared by the method of any one of claims 1-11 or the lithium disilicate glass-ceramic composite material of claim 12 in dental materials, bone materials, backboard materials of communication tools or materials of precise ceramic parts.