A synergistically phase-transition reinforced dental zirconia material, a preparation method and application thereof

Abstract

The application discloses a kind of synergic phase change reinforced dental zirconia materials and preparation method and application thereof, it is related to ceramic material technical field, the preparation method includes the following steps: zirconium oxychloride solution and polyvinyl alcohol solution are mixed, after drying, heat treatment is carried out, and ZrC ceramic powder is obtained;Then mixed with yttria-stabilized zirconia (Y-PSZ), and composite powder is obtained;Composite powder is hot-pressed sintering, cooling, and pre-sintered body is obtained;Ar-O2 mixed gas is introduced, and controllable oxidation is carried out, and the pre-sintered body of oxidation phase change reinforcement is obtained;Again high-temperature sintering is carried out, and the dental zirconia material of synergic phase change reinforcement is obtained.The application also discloses the above-mentioned dental zirconia material of synergic phase change reinforcement and its application in the preparation of dental products.The method introduces ZrC, utilizes the compressive stress field formed by ZrC oxidation and crystal type transformation in high-temperature sintering process, realizes the reinforcement of yttria-stabilized zirconia dental ceramic, and significantly improves its mechanical strength.

Description

Technical Field

[0001] This invention relates to the field of ceramic materials technology, specifically to a dental zirconia material with synergistic phase transformation strengthening, its preparation method, and its application. Background Technology

[0002] Zirconia (ZrO2)-based ceramic materials are widely used in dental materials due to their excellent biocompatibility, color similar to natural teeth, high strength, and good wear resistance. Examples include crowns, dentures, and dental posts. ZrO2 ceramics have three crystal structures: orthorhombic, tetragonal, and cubic. A density difference exists between the orthorhombic and tetragonal crystal forms, leading to volume changes during their transformation. During ZrO2 ceramic preparation, a transformation from tetragonal to orthorhombic crystals occurs, accompanied by volume expansion and potential cracking. Adding a small amount of the stabilizer yttrium oxide (Y2O3) to ZrO2 can suppress this crystal transformation. Furthermore, this small amount of transformation actually contributes to increased strength; the resulting material is called partially stabilized zirconia (Y-PSZ). Studies have shown that when the Y2O3 content is 3 mol%, the prepared Y2O3-stabilized ZrO2 ceramic exhibits the highest strength. However, clinical results show that the tetragonal crystal form is a metastable phase and will continue to transform into the orthorhombic crystal form under the influence of water, causing material damage. This phenomenon is also known as the low-temperature aging effect. By increasing the Y₂O₃ content to above 5 mol%, the tetragonal crystal content can be effectively reduced, avoiding subsequent crystal transformation and thus effectively weakening the low-temperature aging effect. However, the reduction of the tetragonal crystal form also reduces its strengthening effect during the tetragonal-orthorhombic crystal transformation process, resulting in a significant decrease in the material's strength and greatly limiting its clinical application. Therefore, how to improve its strength while ensuring good resistance to low-temperature aging has become an urgent problem to be solved for the clinical application of ZrO₂ ceramics.

[0003] Existing solutions to the above problems mainly fall into two categories: one is to address the low-temperature aging issue by increasing the Y₂O₃ content, followed by traditional strengthening methods such as grain refinement and second-phase introduction. The drawback of this approach is its insufficient strengthening effect, being less effective than the strengthening effect achieved through crystal transformation. The other approach retains the strengthening effect of crystal transformation and then improves resistance to low-temperature aging, for example, through surface coating technology or surface carburizing technology. The drawback of this approach is that the stability of the surface coating or carburized layer cannot be guaranteed, the interfacial bonding between the coating and the substrate is weak, and once the coating is damaged, it cannot provide effective protection.

[0004] In summary, existing technologies cannot achieve both good low-temperature aging resistance and good mechanical strength in Y2O3-stabilized ZrO2 dental ceramic materials. Summary of the Invention

[0005] To address the aforementioned technical problems, the present invention aims to provide a dental zirconia material with synergistic phase transformation strengthening, its preparation method, and its application. This method uses Y2O3-stabilized ZrO2, which has good resistance to low-temperature aging, as a raw material, and introduces ZrC into it. By utilizing the volume expansion effect during the oxidation of ZrC to ZrO2 and the secondary expansion during the tetragonal-orthorhombic transformation of the generated ZrO2, the strengthening and toughening of Y2O3-stabilized ZrO2 dental ceramics is achieved. While ensuring its excellent resistance to low-temperature aging, its mechanical strength is significantly improved.

[0006] The technical solution of this invention to solve the above-mentioned technical problems is as follows: A method for preparing a dental zirconia material with synergistic phase transformation strengthening is provided, comprising the following steps:

[0007] (1) Dissolve zirconium dichloride octahydrate and polyvinyl alcohol in water to obtain zirconium dichloride solution and polyvinyl alcohol solution respectively; mix zirconium dichloride solution and polyvinyl alcohol solution evenly and react fully, dry and then heat treat to obtain ZrC ceramic powder;

[0008] (2) The ZrC ceramic powder obtained in step (1) is ball-milled and sieved, then mixed with Y2O3-stabilized ZrO2, and ball-milled, dried and ground to obtain composite powder;

[0009] (3) The composite powder obtained in step (2) is heated to 1200-1300℃ under pressure and sintered, and then cooled to room temperature to obtain a pre-sintered body;

[0010] (4) Under the condition of introducing oxygen and argon, the pre-sintered body obtained in step (3) is heated to 800-1000℃ to carry out oxidation phase transformation, and then cooled to room temperature to obtain an oxidation phase transformation strengthened pre-sintered body;

[0011] (5) The pre-sintered body with oxidation phase transformation strengthening obtained in step (4) is heated to 1400-1550℃ and sintered, and then cooled to room temperature to obtain dental zirconia material with synergistic phase transformation strengthening.

[0012] Further, in step (1), the concentration of the zirconium dichloride solution is 0.08-0.1 g / mL; the concentration of the polyvinyl alcohol solution is 0.4-0.6 g / mL; the volume ratio of the zirconium dichloride solution to the polyvinyl alcohol solution is 1:0.8-1.2; the heat treatment temperature in step (1) is 1500-1700℃, and the heat treatment time is 1-3 h.

[0013] Furthermore, in step (1), the stirring method is to use magnetic stirring at a speed of 300-600 r / min for 1-3 h.

[0014] Furthermore, in step (1), the drying temperature is 60-80℃.

[0015] Furthermore, in step (2), the ZrC ceramic powder is ball-milled and then passed through a 500-mesh sieve.

[0016] Furthermore, in step (2), the Y2O3 content of Y2O3 stabilizing ZrO2 is 5-8 mol.

[0017] Furthermore, in step (2), the mass ratio of ZrC ceramic powder to Y2O3 stabilized ZrO2 is 0.01-0.05:100.

[0018] Furthermore, in step (3), sintering is carried out at 35-45 MPa and 1200-1300℃ for 6-8 h.

[0019] Furthermore, in step (4), the flow rate of argon is 300-500 mL / min; the flow rate of oxygen is 20-40 mL / min.

[0020] Furthermore, in step (4), the oxidation phase transition time is 2-4 h.

[0021] Furthermore, in step (5), the sintering time is 4-6 h.

[0022] The present invention also provides a method for preparing the above-mentioned synergistic phase transformation reinforced dental zirconia material, and the synergistic phase transformation reinforced dental zirconia material obtained therefrom.

[0023] This invention also provides the application of the above-mentioned synergistic phase transformation reinforced zirconia material for dental use in the preparation of dental products.

[0024] The present invention has the following beneficial effects:

[0025] 1. This invention provides a synergistic phase transformation strengthening method for dental ceramics with Y2O3-stabilized ZrO2 resistant to low-temperature aging. Specifically, ZrC is introduced into the raw material, and the volume expansion effect during the oxidation of ZrC to ZrO2 and the secondary expansion during the tetragonal-orthorhombic transformation of the generated ZrO2 are used to effectively strengthen the ceramic.

[0026] 2. This method can adjust the expansion effect of synergistic phase transition by controlling the amount of ZrC introduced. The enhancement effect is adjustable, the operation is simple, the cost is low, and it is conducive to large-scale production.

[0027] 3. According to the biaxial bending test, the biaxial bending strength of the dental zirconia ceramic material prepared by the present invention after synergistic phase change strengthening reached 683 MPa, while the biaxial bending strength of the dental zirconia ceramic material without strengthening was only 527 MPa, which is 29.6%. Attached Figure Description

[0028] Figure 1 A flowchart illustrating the fabrication process of the materials used in Example 1;

[0029] Figure 2 XRD pattern of dental zirconia material prepared for Comparative Example 3;

[0030] Figure 3 The image shows the XRD pattern of the ZrC ceramic material prepared in step (1) of Example 3;

[0031] Figure 4 The XRD pattern of the pre-sintered body with enhanced oxidation phase transformation prepared in step (4) of Example 3;

[0032] Figure 5 Diagram of the test mold for the double-column bending test;

[0033] Figure 6 This is a sample image before the double-column bending experiment in Example 1;

[0034] Figure 7 The images show the damage after the double-column bending test in Examples 1-3 and Comparative Example 3;

[0035] Figure 8 Load-displacement curves of the dental zirconia material prepared in Comparative Example 3;

[0036] Figure 9 The load-displacement curve of the synergistic phase transformation reinforced dental zirconia material prepared in Example 1 is shown.

[0037] Figure 10 The load-displacement curve of the synergistic phase transformation reinforced dental zirconia material prepared in Example 2 is shown.

[0038] Figure 11 The load-displacement curve is shown for the synergistic phase transformation reinforced dental zirconia material prepared in Example 3. Detailed Implementation

[0039] The principles and features of this invention are described below. The examples given are for illustrative purposes only and are not intended to limit the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer should be followed. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0040] Example 1

[0041] A dental zirconia material with synergistic phase transformation strengthening, the preparation method of which includes the following steps (preparation process as follows) Figure 1 (as shown)

[0042] (1) Dissolve zirconium dichloride octahydrate and polyvinyl alcohol in water to obtain a 0.09 g / mL zirconium dichloride solution and a 0.5 g / mL polyvinyl alcohol solution; mix the zirconium dichloride solution and the polyvinyl alcohol solution at a volume ratio of 1:1, stir magnetically at a speed of 300 r / min for 3 h, dry at 60℃ and heat-treat at 1500℃ for 3 h to obtain ZrC ceramic powder;

[0043] (2) The ZrC ceramic powder obtained in step (1) is ball-milled until it passes through a 500-mesh sieve, and then mixed with Y2O3 stabilized ZrO2 (Y2O3 content is 8 mol%) at a mass ratio of 0.01:100. After ball milling, drying and grinding, composite powder is obtained.

[0044] (3) The composite powder obtained in step (2) is heated to 1200℃ and pressurized to 45 MPa in a hot press furnace for 8 h, and then cooled to room temperature to obtain a pre-sintered body; when heating, the initial pressure is 12 MPa, the pressurization rate is 0.12 MPa / min, and the heating rate is 5 ℃ / min; when cooling, the depressurization rate is 0.11 MPa / min, and the cooling rate is 3 ℃ / min.

[0045] (4) Under the condition of oxygen and argon, the pre-sintered body obtained in step (3) is heated to 1000℃ for oxidation phase transformation treatment for 4 h, and then cooled to room temperature to obtain an oxidation phase transformation strengthened pre-sintered body; the flow rate of argon is 300 mL / min; the flow rate of oxygen is 40 mL / min; the heating rate is 3 ℃ / min; and the cooling rate is 3 ℃ / min.

[0046] (5) The pre-sintered body with oxidation phase transformation strengthening obtained in step (4) is heated to 1500℃, held for sintering for 4 h, and then cooled to room temperature to obtain dental zirconia material with synergistic phase transformation strengthening; the heating rate is 5 ℃ / min and the cooling rate is 3 ℃ / min.

[0047] Example 2

[0048] A dental zirconia material with synergistic phase transformation strengthening, the preparation method of which includes the following steps:

[0049] (1) Dissolve zirconium dichloride octahydrate and polyvinyl alcohol in water to obtain a 0.08 g / mL zirconium dichloride solution and a 0.4 g / mL polyvinyl alcohol solution; mix the zirconium dichloride solution and the polyvinyl alcohol solution at a volume ratio of 1:0.8, stir magnetically at a speed of 450 r / min for 2 h, dry at 70℃ and heat-treat at 1600℃ for 2 h to obtain ZrC ceramic powder;

[0050] (2) The ZrC ceramic powder obtained in step (1) is ball-milled until it passes through a 500-mesh sieve, and then mixed with Y2O3 stabilized ZrO2 (Y2O3 content is 6.5 mol%) at a mass ratio of 0.02:100. After ball milling, drying and grinding, composite powder is obtained.

[0051] (3) The composite powder obtained in step (2) is heated to 1250 ℃ and pressurized to 40 MPa in a hot press furnace for 7 h, and then cooled to room temperature to obtain a pre-sintered body; when heating, the initial pressure is 12 MPa, the pressurization rate is 0.1 MPa / min, and the heating rate is 5 ℃ / min; when cooling, the depressurization rate is 0.11 MPa / min, and the cooling rate is 3 ℃ / min.

[0052] (4) Under the condition of introducing oxygen and argon, the pre-sintered body obtained in step (3) is heated to 900 °C for oxidation phase transformation treatment for 3 h, and then cooled to room temperature to obtain an oxidation phase transformation strengthened pre-sintered body; the flow rate of argon is 400 mL / min; the flow rate of oxygen is 30 mL / min; the heating rate is 3 °C / min; and the cooling rate is 3 °C / min.

[0053] (5) The pre-sintered body with oxidation phase transformation strengthening obtained in step (4) is heated to 1550 °C, held for sintering for 6 h, and then cooled to room temperature to obtain dental zirconia material with synergistic phase transformation strengthening; the heating rate is 5 °C / min and the cooling rate is 3 °C / min.

[0054] Example 3

[0055] A dental zirconia material with synergistic phase transformation strengthening, the preparation method of which includes the following steps:

[0056] (1) Dissolve zirconium dichloride octahydrate and polyvinyl alcohol in water to obtain a 0.08 g / mL zirconium dichloride solution and a 0.4 g / mL polyvinyl alcohol solution; mix the zirconium dichloride solution and the polyvinyl alcohol solution at a volume ratio of 1:0.8, stir magnetically at a speed of 600 r / min for 1 h, dry at 80℃ and heat-treat at 1700℃ for 1 h to obtain ZrC ceramic powder;

[0057] (2) The ZrC ceramic powder obtained in step (1) is ball-milled until it passes through a 500-mesh sieve, and then mixed with Y2O3 stabilized ZrO2 (Y2O3 content is 5 mol%) at a mass ratio of 0.05:100. After ball milling, drying and grinding, composite powder is obtained.

[0058] (3) The composite powder obtained in step (2) is heated to 1300 ℃ and pressurized to 35 MPa in a hot press furnace and sintered for 6 h, and then cooled to room temperature to obtain a pre-sintered body; when heating, the initial pressure is 12 MPa, the pressurization rate is 0.09 MPa / min, and the heating rate is 5 ℃ / min; when cooling, the depressurization rate is 0.11 MPa / min, and the cooling rate is 3 ℃ / min.

[0059] (4) Under the condition of oxygen and argon, the pre-sintered body obtained in step (3) is heated to 800℃ for oxidation phase transformation treatment for 4 h, and then cooled to room temperature to obtain the pre-sintered body strengthened by oxidation phase transformation; the flow rate of argon is 500 mL / min; the flow rate of oxygen is 20 mL / min; the heating rate is 3 ℃ / min; and the cooling rate is 3 ℃ / min.

[0060] (5) The pre-sintered body with oxidation phase transformation strengthening obtained in step (4) is heated to 1500℃, held for sintering for 7 h, and then cooled to room temperature to obtain dental zirconia material with synergistic phase transformation strengthening; the heating rate is 5 ℃ / min and the cooling rate is 3 ℃ / min.

[0061] Comparative Example 1

[0062] A dental zirconia material, the preparation method of which differs from that of Example 1, is without step (1), and without ZrC in step (2), while the rest is the same as in Example 1.

[0063] Comparative Example 2

[0064] A dental zirconia material, the preparation method of which differs from that of Example 2, is that it does not include step (1), and step (2) does not contain ZrC, while the rest is the same as that of Example 2.

[0065] Comparative Example 3

[0066] A dental zirconia material, the preparation method of which differs from that of Example 3, is without step (1), and without ZrC in step (2), while the rest is the same as in Example 3.

[0067] Experimental Example 1: XRD Image Analysis

[0068] The products obtained from Comparative Examples 1-3 have basically the same characteristics. The following tests are conducted using Comparative Example 3 as an example:

[0069] XRD patterns were analyzed for the dental zirconia material treated in Comparative Example 3, the ZrC ceramic powder prepared in step (1) of Example 3, and the oxidation product formed after oxidation in step (4) of Example 3. The results are as follows: Figures 2-4 As shown.

[0070] The results showed that the oxidation product formed after ZrC oxidation phase transformation was m-phase ZrO2, while the m-phase was extremely low in dental zirconia materials without m-ZrO2 doping. This indicates that the ZrO2 formed after ZrC oxidation can generate tm phase transformation during the preparation of dental zirconia materials.

[0071] Test Example 2: Biaxial Bending Test

[0072] Biaxial bending tests were performed on the synergistic phase transformation reinforced dental zirconia materials prepared in Comparative Examples 1-3 and Examples 1-3, respectively.

[0073] According to the biaxial bending strength test standard in ISO 6872:2024, the international standard for dental ceramic materials, a universal testing machine was used for biaxial bending strength testing. The specimen size was 15 (± 0.5) mm × 1.5 (± 0.2) mm, the loading range was 2 kN, the loading speed was 0.5 mm / min, and the inlet force was set to 5 N. The computer collected relevant data through load and displacement sensors. The biaxial bending strength was obtained by the following calculation formula:

[0074]

[0075] in:

[0076]

[0077] In the formula: σ is the biaxial bending strength, MPa; P is the maximum load, N; b is the thickness of the specimen, mm; υ is the Poisson's ratio of the material, taken as 0.25; r1 is the radius of the support circle, mm; r2 is the radius of the load zone, mm; r3 is the radius of the specimen, mm.

[0078] The biaxial bending performance test process is as follows: Figure 5 and Figure 6 As shown, Figure 5 To test the mold, Figure 6 This is a sample image of Example 1 before testing.

[0079] The products obtained in Comparative Examples 1-3 have basically the same characteristics. The following analysis of fracture failure is based on Comparative Example 3 as an example:

[0080] The actual images of the fracture failures of Examples 1-3 and Comparative Example 3 after biaxial bending tests are shown below. Figure 7 As shown, the load-displacement correlation data during biaxial bending tests of different materials are respectively as follows: Figures 8-11 As shown in Table 1, the biaxial bending strength results are as follows.

[0081] Table 1. Results of Biaxial Bending Strength Test

[0082]

[0083] Depend on Figures 8-11 It can be seen that the dental zirconia materials after synergistic phase transformation strengthening in Examples 1-3 still maintain the original stress response characteristics. Table 1 shows that the biaxial bending strength of the dental zirconia ceramic materials prepared according to the process of this invention is greater than 500 MPa, which meets the strength requirements for ceramic teeth in the international standard for dental ceramic materials ISO 6872:2024 (greater than 100 MPa for anterior teeth and greater than 500 MPa for molars). The sample after synergistic phase transformation strengthening in Example 3 can reach a maximum biaxial bending strength of 683 MPa, while the biaxial bending strength of the unstrengthened dental zirconia ceramic material is only 527 MPa. The biaxial bending strength of this invention is improved by 29.6%, which has a significant strengthening effect.

[0084] 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 or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a dental zirconia material with synergistic phase transformation strengthening, characterized in that, Includes the following steps: (1) Dissolve zirconium dichloride octahydrate and polyvinyl alcohol in water to obtain zirconium dichloride solution and polyvinyl alcohol solution respectively; The zirconium dichloride solution and polyvinyl alcohol solution were mixed and stirred evenly and allowed to react fully. After drying, they were heat-treated to obtain ZrC ceramic powder. (2) The ZrC ceramic powder obtained in step (1) is ball-milled and sieved, and then mixed with Y2O3 stabilized ZrO2. After ball milling, drying and grinding, a composite powder is obtained; the mass ratio of the ZrC ceramic powder to the Y2O3 stabilized ZrO2 is 0.01-0.05:

100. (3) The composite powder obtained in step (2) is heated to 1200-1300℃ under pressure and sintered, and then cooled to room temperature to obtain a pre-sintered body; (4) Under the condition of introducing oxygen and argon, the pre-sintered body obtained in step (3) is heated to 800-1000℃ to carry out oxidation phase transformation, and then cooled to room temperature to obtain an oxidation phase transformation strengthened pre-sintered body; (5) The pre-sintered body with oxidation phase transformation strengthening obtained in step (4) is heated to 1400-1550℃ and sintered, and then cooled to room temperature to obtain dental zirconia material with synergistic phase transformation strengthening.

2. The preparation method according to claim 1, characterized in that, In step (1), the concentration of the zirconium dichloride solution is 0.08-0.1 g / mL; the concentration of the polyvinyl alcohol solution is 0.4-0.6 g / mL; the volume ratio of the zirconium dichloride solution to the polyvinyl alcohol solution is 1:0.8-1.2; the heat treatment temperature in step (1) is 1500-1700℃, and the heat treatment time is 1-3h.

3. The preparation method according to claim 1, characterized in that, In step (2), the Y2O3 content of the Y2O3 stabilized ZrO2 is 5-8 mol.

4. The preparation method according to claim 1, characterized in that, In step (3), sintering is carried out at 35-45 MPa and 1200-1300℃ for 6-8 h.

5. The preparation method according to claim 1, characterized in that, In step (4), the flow rate of argon is 300-500 mL / min; the flow rate of oxygen is 20-40 mL / min.

6. The preparation method according to claim 1, characterized in that, In step (4), the oxidation phase transition takes 2-4 hours.

7. The preparation method according to claim 1, characterized in that, In step (5), the sintering time is 4-6 h.

8. The dental zirconia material with synergistic phase transformation strengthening prepared by the preparation method according to any one of claims 1-7.

9. The application of the synergistic phase transformation reinforced dental zirconia material of claim 8 in the preparation of dental articles.

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