A zirconia dental ceramic powder and its preparation method

Abstract

This invention belongs to the field of zirconia ceramic technology, and provides a zirconia dental ceramic powder and its preparation method. The zirconia dental ceramic powder comprises zirconia, yttrium oxide, and calcium oxide; the molar ratio of yttrium oxide, calcium oxide, and zirconia is 2-4:13-17:100. This invention synthesizes zirconia-based cubic polycrystalline ceramic powder hydrothermally in a reactor by adding yttrium chloride and excess calcium chloride to a zirconium oxychloride solution; partial agglomeration is achieved by controlling the powder preparation process. The zirconia dental ceramic powder of this invention has a high calcium content. Due to the migration and uneven diffusion of calcium, the zirconia ceramic prepared using this powder has a large grain size and contains uniformly sized pores, reducing the hardness of the zirconia ceramic. This solves the technical problem of high hardness in zirconia ceramic restorations prepared from existing zirconia dental ceramic powders.

Description

Technical Field

[0001] This invention relates to the field of zirconia ceramics technology, and in particular to a zirconia dental ceramic powder and its preparation method. Background Technology

[0002] Zirconia ceramics have become a widely used all-ceramic restorative material due to their excellent stability, superior biocompatibility, and aesthetics. Zirconia ceramics are sintered from zirconia powder with a small amount of other metal oxides added. The chemical composition and crystal structure of the zirconia powder have a decisive influence on the performance of zirconia ceramics. 3Y-TZP ceramics possess superior flexural strength, fracture toughness, good biocompatibility, and excellent optical properties. However, crowns and bridges made of 3Y-TZP ceramics have a hardness far exceeding that of tooth enamel, easily leading to rapid pathological wear of the opposing natural teeth and inducing other diseases. The Vickers hardness of commercially available 3Y-TZP dental ceramics is 12–14 GPa, while the Vickers hardness of tooth enamel is 2.9–4.8 GPa.

[0003] Therefore, there is an urgent clinical need to modify the microstructure of the occlusal surface area of ​​a full zirconium crown to obtain a zirconium oxide ceramic that reduces hardness, allows the full zirconium crown and the opposing tooth to wear down synchronously and equally at a normal speed, and ensures the health of oral organs. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art by providing a zirconia dental ceramic powder and its preparation method.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides a zirconia dental ceramic powder comprising zirconia, yttrium oxide, and calcium oxide; wherein the molar ratio of yttrium oxide, calcium oxide, and zirconia is 2-4:13-17:100.

[0007] The present invention also provides a method for preparing the aforementioned zirconia dental ceramic powder, comprising the following steps:

[0008] 1) Mix zirconium oxychloride solution, yttrium chloride and calcium chloride to obtain the first solution;

[0009] 2) Mix the first solution, polyethylene glycol, and ammonia to obtain the second solution;

[0010] 3) After the second solution undergoes a hydrothermal reaction, it is filtered, and the filter residue is washed and dried sequentially to obtain the first powder;

[0011] 4) The first powder and anhydrous ethanol are ball-milled to obtain a slurry; the slurry is then dried and ground sequentially to obtain the second powder;

[0012] 5) The second powder is calcined to obtain zirconia dental ceramic powder.

[0013] Preferably, the concentration of zirconium ions in the zirconium oxychloride solution in step 1) is 0.15–0.25 mol / L; in the first solution, the molar ratio of yttrium ions to zirconium ions is 5–7:100, and the molar ratio of calcium ions to zirconium ions is 30–90:100.

[0014] Preferably, the mixing temperature in step 1) is 50–80°C.

[0015] Preferably, in step 2), the volume ratio of polyethylene glycol to the first solution is 1-3:100, the amount of ammonia added is such that the pH of the second solution is 9-10, and the mass concentration of ammonia is 5-20%.

[0016] Preferably, the temperature of the hydrothermal reaction in step 3) is 190–210°C, and the time of the hydrothermal reaction is 48–72 h.

[0017] Preferably, the washing reagent in step 3) is water, and the washing continues until there are no chloride ions in the solution; the drying temperature is 60-80°C.

[0018] Preferably, the ball milling time in step 4) is 4 to 8 hours, and the ball milling speed is 300 to 500 r / min.

[0019] Preferably, the drying temperature in step 4) is 50-70°C, and the particle size of the second powder is ≥60 mesh.

[0020] Preferably, the calcination temperature in step 5) is 550–650°C, and the calcination time is 1–3 h.

[0021] The beneficial effects of this invention include:

[0022] 1) This invention synthesizes zirconia-based cubic polycrystalline ceramic powder hydrothermally in a reactor by adding yttrium chloride and excess calcium chloride to a zirconium oxychloride solution. By controlling the powder preparation process, partial agglomeration is achieved. The zirconia dental ceramic powder of this invention has a high calcium content. During sintering, the migration and uneven diffusion of calcium lead to large grain size, increased internal defects, and uniformly sized pores, reducing the hardness of the zirconia ceramic. This solves the technical problem of high hardness in zirconia ceramic restorations prepared from existing zirconia dental powders.

[0023] 2) The preparation method of this invention has mild reaction conditions, a stable limit of calcium solid solubility, low precision requirements for the content of the precursor zirconium oxychloride, and good repeatability. This method is suitable for preparing powders for low-hardness zirconia-based ceramics, and is particularly suitable for preparing dental zirconia ceramic occlusal surfaces. Attached Figure Description

[0024] Figure 1 The image shows the XRD pattern of the zirconia dental ceramic powder from Example 1.

[0025] Figure 2 Here is a SEM image of the zirconia dental ceramic powder from Example 1;

[0026] Figure 3 The infrared Raman spectrum of the zirconia dental ceramic of Example 1 is shown below.

[0027] Figure 4 Here is a SEM image of the zirconia dental ceramic from Example 1;

[0028] Figure 5 The image shown is an EPMA line scan of the zirconia dental ceramic of Example 1.

[0029] Figure 6 The image shows the surface scan of Ca distribution in the zirconia dental ceramic of Example 1.

[0030] Figure 7 This is a Vickers hardness indentation diagram of the zirconia dental ceramic of Example 1. Detailed Implementation

[0031] This invention provides a zirconia dental ceramic powder comprising zirconia, yttrium oxide, and calcium oxide; wherein the molar ratio of yttrium oxide, calcium oxide, and zirconia is 2-4:13-17:100.

[0032] In the zirconia dental ceramic powder of the present invention, the molar ratio of yttrium oxide, calcium oxide and zirconia is preferably 2.5-3.5:14-16:100, and more preferably 3:15:100.

[0033] The present invention also provides a method for preparing the aforementioned zirconia dental ceramic powder, comprising the following steps:

[0034] 1) Mix zirconium oxychloride solution, yttrium chloride and calcium chloride to obtain the first solution;

[0035] 2) Mix the first solution, polyethylene glycol, and ammonia to obtain the second solution;

[0036] 3) After the second solution undergoes a hydrothermal reaction, it is filtered, and the filter residue is washed and dried sequentially to obtain the first powder;

[0037] 4) The first powder and anhydrous ethanol are ball-milled to obtain a slurry; the slurry is then dried and ground sequentially to obtain the second powder;

[0038] 5) The second powder is calcined to obtain zirconia dental ceramic powder.

[0039] In this invention, the concentration of zirconium ions in the zirconium oxychloride solution in step 1) is preferably 0.15–0.25 mol / L, more preferably 0.18–0.22 mol / L, and even more preferably 0.20 mol / L; in the first solution, the molar ratio of yttrium ions to zirconium ions is preferably 5–7:100, more preferably 5.5–6.5:100, and even more preferably 6:100; the molar ratio of calcium ions to zirconium ions is preferably 30–90:100, more preferably 40–80:100, and even more preferably 50–60:100.

[0040] In this invention, the mixing temperature in step 1) is preferably 50-80°C, more preferably 60-70°C, and even more preferably 65°C; the mixing is carried out under stirring conditions until the yttrium oxide powder and calcium oxide powder are completely dissolved.

[0041] In this invention, the volume ratio of polyethylene glycol to the first solution in step 2) is preferably 1-3:100, more preferably 1.5-2.5:100, and even more preferably 2:100; the amount of ammonia added is such that the pH value of the second solution is preferably 9-10, more preferably 9.5; the mass concentration of ammonia is preferably 5-20%, more preferably 8-15%, and even more preferably 10-12%.

[0042] In this invention, the second solution is added to the reaction vessel for hydrothermal reaction. The filling amount of the second solution in the reaction vessel is preferably 70-85%, more preferably 73-80%, and even more preferably 75-77%.

[0043] In this invention, the temperature of the hydrothermal reaction in step 3) is preferably 190-210°C, more preferably 195-205°C, and even more preferably 200°C; the time of the hydrothermal reaction is preferably 48-72h, more preferably 52-68h, and even more preferably 55-60h.

[0044] In this invention, the washing reagent in step 3) is preferably water, and the washing continues until there are no chloride ions in the solution. The standard for detecting the absence of chloride ions is that no precipitate appears when silver nitrate solution is added dropwise to the washed solution. The molar concentration of the silver nitrate solution is preferably 0.08-0.12 mol / L, more preferably 0.10 mol / L. The drying temperature is preferably 60-80℃, more preferably 65-75℃, and more preferably 70℃.

[0045] In this invention, the ball milling time in step 4) is preferably 4 to 8 hours, more preferably 5 to 7 hours, and even more preferably 6 hours; the ball milling speed is preferably 300 to 500 r / min, more preferably 350 to 450 r / min, and even more preferably 400 r / min.

[0046] In this invention, the amount of anhydrous ethanol is preferably sufficient to cover the volume of the zirconium balls in the milling jar; the amount of the first powder is not limited.

[0047] In this invention, the drying temperature in step 4) is preferably 50-70°C, more preferably 55-65°C, and even more preferably 60°C; the particle size of the second powder is preferably ≥60 mesh.

[0048] In this invention, the calcination temperature in step 5) is preferably 550-650°C, more preferably 580-620°C, and even more preferably 600°C; the calcination time is preferably 1-3 hours, more preferably 1.5-2.5 hours, and even more preferably 2 hours.

[0049] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0050] Example 1

[0051] Place 150 mL of zirconium oxychloride solution (Zr ion concentration of 0.2 mol / L), yttrium chloride powder, and calcium chloride powder in a beaker, place the beaker on a magnetic stirrer, and stir at 200 r / min at 50 °C until the yttrium chloride powder and calcium chloride powder are completely dissolved and homogeneous to obtain the first solution (yttrium ions are 6% of the molar amount of zirconium ions, and calcium ions are 30% of the molar amount of zirconium ions).

[0052] Polyethylene glycol (2% of the volume of the first solution) was added to the first solution, and then ammonia (5% by mass) was added dropwise at a rate of two drops per second. The mixture was stirred at a rate of 200 r / min to obtain a second solution with a pH of 9.

[0053] The second solution was placed in a 200 mL reaction vessel and hydrothermally reacted at 200 °C for 48 h. After the hydrothermal reaction was completed, the solution was filtered. The precipitate obtained after filtration was repeatedly washed with distilled water until no precipitate was found when 0.10 mol / L silver nitrate solution was added to the washed solution (i.e., no chloride ions were detected in the solution). The precipitate was then placed in an oven and dried at 60 °C to obtain the first powder.

[0054] The first powder was placed in a ball mill jar containing zirconium balls, anhydrous ethanol was added, and then the mixture was ball-milled for 4 hours (400 r / min) in a horizontal ball mill to obtain a white slurry. The white slurry was dried in an oven at 60°C, then ground and passed through a 60-mesh sieve to obtain the second powder. The second powder was placed in a crucible and calcined at 600°C for 2 hours to obtain zirconium oxide dental ceramic powder.

[0055] The XRD pattern of the zirconia dental ceramic powder in Example 1 is shown below. Figure 1As shown, the SEM image of the zirconia dental ceramic powder of Example 1 is as follows. Figure 2 As shown. By Figure 1 It can be seen that the zirconia dental ceramic powder is a cubic phase. Figure 2 It can be seen that the primary particle size of the zirconia dental ceramic powder is about 20 nm, and the primary particles form hard agglomerates in some areas.

[0056] Example 2

[0057] Place 150 mL of zirconium oxychloride solution (Zr ion concentration of 0.18 mol / L), yttrium chloride powder, and calcium chloride powder in a beaker, place the beaker on a magnetic stirrer, and stir at 200 r / min at 60 °C until the yttrium chloride powder and calcium chloride powder are completely dissolved and homogeneous to obtain the first solution (yttrium ions are 6% of the molar amount of zirconium ions, and calcium ions are 60% of the molar amount of zirconium ions).

[0058] Polyethylene glycol (1.5% of the volume of the first solution) was added to the first solution, and then ammonia (10% by mass) was added dropwise at a rate of two drops per second. The mixture was stirred at a rate of 200 r / min to obtain a second solution with a pH of 10.

[0059] The second solution was placed in a 200 mL reaction vessel and hydrothermally reacted at 195 °C for 72 h. After the hydrothermal reaction was completed, the solution was filtered. The precipitate obtained after filtration was repeatedly washed with distilled water until no precipitate was found when 0.10 mol / L silver nitrate solution was added to the washed solution (i.e., no chloride ions were detected in the solution). The precipitate was then placed in an oven and dried at 80 °C to obtain the first powder.

[0060] The first powder was placed in a ball mill jar containing zirconium balls, anhydrous ethanol was added, and then the mixture was ball-milled for 6 hours (400 r / min) in a horizontal ball mill to obtain a white slurry. The white slurry was dried in an oven at 55°C, then ground and passed through a 60-mesh sieve to obtain the second powder. The second powder was placed in a crucible and calcined at 650°C for 1.5 hours to obtain zirconium oxide dental ceramic powder.

[0061] Example 3

[0062] Place 150 mL of zirconium oxychloride solution (Zr ion concentration of 0.22 mol / L), yttrium chloride powder, and calcium chloride powder in a beaker, place the beaker on a magnetic stirrer, and stir at 200 r / min at 70 °C until the yttrium chloride powder and calcium chloride powder are completely dissolved and homogeneous to obtain the first solution (yttrium ions account for 6.5% of the molar amount of zirconium ions, and calcium ions account for 90% of the molar amount of zirconium ions).

[0063] Polyethylene glycol (2.5% of the volume of the first solution) was added to the first solution, and then ammonia (12% by mass) was added dropwise at a rate of two drops per second. The mixture was stirred at a rate of 200 r / min to obtain a second solution with a pH of 10.

[0064] The second solution was placed in a 200 mL reaction vessel and hydrothermally reacted at 205 °C for 60 h. After the hydrothermal reaction was completed, the solution was filtered. The precipitate obtained after filtration was repeatedly washed with distilled water until no precipitate was found when 0.10 mol / L silver nitrate solution was added to the washed solution (i.e., no chloride ions were detected in the solution). The precipitate was then placed in an oven and dried at 70 °C to obtain the first powder.

[0065] The first powder was placed in a ball mill jar containing zirconium balls, anhydrous ethanol was added, and then the mixture was ball-milled for 6 hours (400 r / min) in a horizontal ball mill to obtain a white slurry. The white slurry was dried in an oven at 65°C, then ground and passed through a 60-mesh sieve to obtain the second powder. The second powder was placed in a crucible and calcined at 580°C for 2.5 hours to obtain zirconium oxide dental ceramic powder.

[0066] The zirconia dental ceramic powders from Examples 1-3 were granulated by adding 3 wt% polyvinyl alcohol (PVA), then dry-pressed under 200 MPa pressure, heated to 600°C at a rate of 1°C / min, held at 600°C for 2 hours to remove the binder, and finally sintered by heating to 1530°C at a rate of 5°C / min for 2 hours to obtain zirconia dental ceramics. SEM, EMPA, and Vickers hardness analyses were performed on the zirconia dental ceramics. The infrared Raman spectrum of the zirconia dental ceramic from Example 1 is shown below. Figure 3 As shown, by Figure 3 It can be seen that zirconia dental ceramics contain no other phases besides the cubic phase. The SEM image of the zirconia dental ceramics in Example 1 is shown below. Figure 4 As shown, by Figure 4 It can be seen that the zirconia dental ceramic has a relatively large grain size and contains pores with a diameter of approximately 1 μm. The EPMA (electron probe microanalysis) line scan of the zirconia dental ceramic in Example 1 is shown below. Figure 5 As shown, after conversion, the molar amount of calcium oxide in the measured area is 14-16% of the molar amount of zirconium oxide. The surface scan image of Ca element in the zirconium dental ceramic of Example 1 is shown below. Figure 6 As shown, Ca migrates and diffuses unevenly during sintering, causing Ca element localization, resulting in numerous internal defects and reducing the ceramic hardness. The Vickers hardness indentation diagram of the zirconia dental ceramic in Example 1 is shown below. Figure 7 As shown, the measured hardness is 7.6 GPa.

[0067] The zirconia dental ceramic of Example 2 has a relatively large grain size of about 10 μm, contains uniformly sized pores, and has a calcium oxide molar amount of 14-16% of the zirconia molar amount. Its Vickers hardness is 8.2 GPa.

[0068] The zirconia dental ceramic of Example 3 has a relatively large grain size of about 10 μm, contains pores of uniform size, has a calcium oxide molar amount of 14 to 16% of the zirconia molar amount, and has a Vickers hardness of 8.5 GPa.

[0069] This invention involves the hydrothermal synthesis of zirconia-based cubic polycrystalline ceramic powder in a reactor by adding yttrium chloride and excess calcium chloride to a zirconium oxychloride solution. The zirconia dental ceramic powder of this invention has a high calcium content, resulting in zirconia ceramics with large grain size and uniformly sized pores, which reduces the hardness of the zirconia ceramic.

[0070] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A zirconia dental ceramic powder, characterized in that, Zirconia dental ceramic powder comprises zirconium oxide, yttrium oxide, and calcium oxide; the molar ratio of yttrium oxide, calcium oxide, and zirconium oxide is 2~4:13~17:100; The method for preparing the zirconia dental ceramic powder includes the following steps: 1) Mix zirconium oxychloride solution, yttrium chloride and calcium chloride to obtain the first solution; 2) Mix the first solution, polyethylene glycol, and ammonia to obtain the second solution; 3) After the second solution undergoes a hydrothermal reaction, it is filtered, and the filter residue is washed and dried sequentially to obtain the first powder; 4) The first powder and anhydrous ethanol are ball-milled to obtain a slurry; The slurry is dried and ground sequentially to obtain the second powder. 5) The second powder is calcined to obtain zirconia dental ceramic powder.

2. The method for preparing zirconia dental ceramic powder according to claim 1, characterized in that, It includes the following steps: 1) Mix zirconium oxychloride solution, yttrium chloride and calcium chloride to obtain the first solution; 2) Mix the first solution, polyethylene glycol, and ammonia to obtain the second solution; 3) After the second solution undergoes a hydrothermal reaction, it is filtered, and the filter residue is washed and dried sequentially to obtain the first powder; 4) The first powder and anhydrous ethanol are ball-milled to obtain a slurry; The slurry is dried and ground sequentially to obtain the second powder. 5) The second powder is calcined to obtain zirconia dental ceramic powder.

3. The preparation method according to claim 2, characterized in that, In step 1), the concentration of zirconium ions in the zirconium oxychloride solution is 0.15~0.25 mol / L; in the first solution, the molar ratio of yttrium ions to zirconium ions is 5~7:100, and the molar ratio of calcium ions to zirconium ions is 30~90:

100.

4. The preparation method according to claim 2 or 3, characterized in that, The mixing temperature in step 1) is 50~80℃.

5. The preparation method according to claim 4, characterized in that, Step 2) The volume ratio of polyethylene glycol to the first solution is 1~3:100, and the amount of ammonia added is such that the pH value of the second solution is 9~10, and the mass concentration of ammonia is 5~20%.

6. The preparation method according to claim 5, characterized in that, Step 3) The hydrothermal reaction temperature is 190~210℃, and the hydrothermal reaction time is 48~72h.

7. The preparation method according to claim 6, characterized in that, Step 3) The washing reagent is water, and the washing continues until there are no chloride ions in the solution; the drying temperature is 60~80℃.

8. The preparation method according to any one of claims 5 to 7, characterized in that, Step 4) The ball milling time is 4~8 hours, and the ball milling speed is 300~500 r / min.

9. The preparation method according to claim 8, characterized in that, Step 4) The drying temperature is 50~70℃, and the particle size of the second powder is ≥60 mesh.

10. The preparation method according to claim 9, characterized in that, Step 5) The calcination temperature is 550~650℃, and the calcination time is 1~3h.

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