Multilayer zirconia ceramic, biscuit, preparation method and application

Abstract

The invention provides a multilayer zirconia ceramic, a biscuit, a preparation method and an application. The biscuit preparation method of the multilayer zirconia ceramic comprises the following steps: S1, providing zirconium powder from the first layer to the nth layer; s2, sequentially superposing the zirconium powder from the first layer to the nth layer from bottom to top, and applying pre-pressure to the zirconium powder in the axial direction after each layer of zirconium powder is superposed, so as to obtain a superposed product; s3, the superposed product is subjected to first compression and first pressure maintaining treatment, and a first compressed body is obtained; performing second compression and second pressure maintaining treatment on the first compressed body to obtain a second compressed body; the second compressed body is subjected to two-way counter-pressing and two-way pressure maintaining treatment in the axial direction, and a first green body is obtained; s4, performing cold isostatic pressing treatment on the first green body to obtain a second green body; and S5, carrying out roasting treatment on the second green body to obtain a biscuit of the multi-layer zirconia ceramic. According to the invention, the deformation of the biscuit can be reduced, and the flexural strength of the multilayer zirconia ceramic can be enhanced, so that the fracture toughness of the multilayer zirconia ceramic is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of dental ceramics, and in particular relates to a multilayer zirconia ceramic, a blank, a preparation method and an application thereof. Background Art

[0002] Zirconia ceramic blocks have become one of the main materials for replacing natural teeth due to their high strength, high hardness, high toughness, limited simulation aesthetic effects and biocompatibility. A variety of colored zirconium oxide powders of different strengths are layered and pressed to prepare dental zirconium oxide restoration materials with uniform strength and color transition, which can gradually increase the strength of the restoration from the cutting end to the neck, reduce the wear on adjacent teeth and opposing teeth, and the high neck strength can be used for long bridge restoration. In addition, the color is gradually deepened from the cutting end to the neck, with a uniform transition, making the color of the restoration closer to natural teeth.

[0003] The Chinese invention patent application with publication number CN111348911A discloses a preparation process for a multi-layered transparency and multi-layered strength denture; it includes the following steps: (1) mixing at least two zirconium oxide powders of different transmittances in different weight proportions to obtain a plurality of mixed zirconium oxide powders of different colors, and then paving them layer by layer in order from dark to light and pre-pressing them to obtain a multi-layered transparency blank; (2) dry pressing and isostatic pressing the multi-layered transparency blank as a whole, and then pre-sintering the multi-layered transparency blank to obtain a multi-layered zirconium oxide ceramic block, and then cutting and processing the multi-layered zirconium oxide ceramic block to form a denture; (3) soaking the denture in a dyeing solution, and then taking it out, drying it, and sintering it to obtain the multi-layered transparency and multi-layered strength denture. Although the denture obtained by the above patent application has a natural and beautiful gradient from the incisal end to the gingival end, it avoids the damage of the zirconia incisal end to the mandibular teeth due to its too hardness. However, the green body of multilayer zirconia ceramics is easily deformed, and the flexural strength of multilayer zirconia ceramics is difficult to control, which affects its industrial application value; in addition, the overall yield of multilayer zirconia ceramics also needs to be controlled.

[0004] In view of this, it is necessary to provide a multilayer zirconia ceramic, a blank, a preparation method and an application thereof, so as to solve or at least alleviate the technical problems of how to reduce the deformation of the blank and how to improve the flexural strength of the multilayer zirconia ceramic. Summary of the invention

[0005] The main purpose of the present invention is to provide a multilayer zirconia ceramic, a blank, a preparation method and an application, aiming to solve or at least alleviate the technical problems of how to reduce the deformation of the blank and how to improve the flexural strength of the multilayer zirconia ceramic.

[0006] To achieve the above object, the present invention provides a method for preparing a green body of a multilayer zirconia ceramic, comprising the steps of:

[0007] S1, providing zirconium powder of the first to nth layers, where n is an integer not less than 2;

[0008] S2, stacking the zirconium powders from the first layer to the nth layer from bottom to top, and applying a pre-pressure to the zirconium powders along the axial direction after stacking each layer of the zirconium powders, to obtain a stacked product;

[0009] S3, performing a first compression on the superimposed product, and performing a first pressure holding treatment after the first compression to obtain a first compressed body; performing a second compression on the first compressed body, and performing a second pressure holding treatment after the second compression to obtain a second compressed body; performing a bidirectional counter-compression on the second compressed body along the axial direction, and performing a bidirectional pressure holding treatment after the bidirectional counter-compression to obtain a first blank;

[0010] S4, performing cold isostatic pressing on the first green body to obtain a second green body;

[0011] S5, calcining the second green body to obtain a green body of a multi-layer zirconia ceramic.

[0012] Furthermore, each layer of zirconium powder contains white zirconium powder, yellow zirconium powder, red zirconium powder and gray zirconium powder; by weight percentage,

[0013] The white zirconium powder comprises 91.5-93.5% ZrO2, 4-6% Y2O3, 1-3% HfO2, and 0.3-0.7% Al2O3; the yellow zirconium powder comprises 89-91% ZrO2, 6-8% Y2O3, 1-3% HfO2, 0.3-0.7% Al2O3, and 0.3-0.7% Fe2O3; the red zirconium powder comprises 89-91% ZrO2, 6-8% Y2O3, 1-3% HfO2, 0.3-0.7% Al2O3, and 0.3-0.7% Er2O3; the gray zirconium powder comprises 88-91% ZrO2, 6-8% Y2O3, 1-2% HfO2, 0.5-1.5% Al2O3, and 0.3-0.7% MnO;

[0014] Furthermore, in the zirconium powder from the first layer to the nth layer, the mass proportion of the white zirconium powder increases successively, and the mass proportions of the yellow zirconium powder, the red zirconium powder and the gray zirconium powder decrease successively.

[0015] Furthermore, the pre-pressure is 1-5 MPa, and the application time of the pre-pressure is 3-10 s;

[0016] The pressure of the first pressure-holding treatment is 1-5 MPa, and the duration is 1-10 s; the pressure of the second pressure-holding treatment is 6-10 MPa, and the duration is 1-10 s; the total pressure of the bidirectional pressure-holding treatment is 25-60 MPa, and the duration of the bidirectional pressure-holding treatment is 5-15 s;

[0017] The stacking is performed in a mold, and the step S3 further comprises: demolding the first green body under the protection of oleic acid.

[0018] Furthermore, the cold isostatic pressing treatment has a pressure of 200-280 MPa and a holding time of 100-200 s;

[0019] The temperature of the calcination treatment is 900-1100° C., and the heat preservation time of the calcination treatment is 1-6 hours.

[0020] The present invention also provides a green blank of multilayer zirconia ceramics, which is prepared by any of the green blank preparation methods described above.

[0021] The present invention also provides a method for preparing a multilayer zirconia ceramic, comprising: preparing a green blank of the multilayer zirconia ceramic by any of the above-mentioned green blank preparation methods, and then sequentially machining and sintering the green blank to obtain the multilayer zirconia ceramic.

[0022] Furthermore, the temperature of the sintering treatment is 1450-1550° C., and the heat preservation time of the sintering treatment is 1-5 hours.

[0023] The present invention also provides a multilayer zirconia ceramic, which is prepared by any of the above-mentioned methods for preparing the multilayer zirconia ceramic.

[0024] The present invention also provides a use of any of the above-described green blanks or any of the above-described multi-layer zirconia ceramics in dentures.

[0025] Compared with the prior art, the present invention has at least the following advantages:

[0026] The present invention can reduce the deformation of the green blank, and can enhance the flexural strength of the multilayer zirconia ceramic, so that the fracture toughness of the multilayer zirconia ceramic can be improved; the present invention can also ensure that the green blank has a higher density, and ensure that the multilayer zirconia ceramic has a higher hardness; in addition, the present invention can improve the overall yield of the multilayer zirconia ceramic, and can obtain green blanks and multilayer zirconia ceramics that meet the standards during multiple preparations. Specifically, the present invention is based on the superposition of multiple layers of zirconium powder, and by applying pre-pressure, a specific method of compression, pressure holding and bidirectional pressure is performed, which can not only realize the layered setting of zirconium powder, but also overcome the increase in deformation and decrease in flexural strength caused by multiple layers of zirconium powder, and can ensure the green blank density, ceramic hardness and overall yield; further, the present invention also ensures the performance and yield of the multilayer zirconia ceramic from the overall preparation process by performing oleic acid protection. DETAILED DESCRIPTION

[0027] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] Furthermore, the technical solutions between the various embodiments of the present invention may be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in the field. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0029] When the embodiments give a numerical range, it should be understood that unless otherwise specified in the present invention, the two endpoints of each numerical range and any value between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used in the present invention are familiar to those skilled in the art and the description of the present invention. Any method, device and material of the prior art similar to or equivalent to the method, device and material in the embodiments of the present invention can also be used to implement the present invention; the present invention uses the same detection method to monitor various indicators in each case.

[0030] The present invention provides a method for preparing a green embryo of a multilayer zirconia ceramic, comprising the steps of:

[0031] S1, providing zirconium powder of the 1st to nth layers, where n is an integer not less than 2.

[0032] The zirconium powder in each layer contains white zirconium powder, yellow zirconium powder, red zirconium powder and grey zirconium powder.

[0033] By mass percentage, white zirconium powder includes 91.5-93.5% ZrO2, 4-6% Y2O3, 1-3% HfO2, 0.3-0.7% Al2O3, accounting for 100% in total; yellow zirconium powder includes 89-91% ZrO2, 6-8% Y2O3, 1-3% HfO2, 0.3-0.7% Al2O3, 0.3-0.7% Fe2O3, accounting for 100% in total; Red zirconium powder includes 89-91% ZrO2, 6-8% Y2O3, 1-3% HfO2, 0.3-0.7% Al2O3, 0.3-0.7% Er2O3, accounting for a total of 100%; gray zirconium powder includes 88-91% ZrO2, 6-8% Y2O3, 1-2% HfO2, 0.5-1.5% Al2O3, 0.3-0.7% MnO, accounting for a total of 100%.

[0034] In the zirconium powder from the first layer to the nth layer, the mass proportion of the white zirconium powder increases successively, and the mass proportions of the yellow zirconium powder, the red zirconium powder and the gray zirconium powder decrease successively.

[0035] For example, n in step S1 is not greater than or equal to 6; when n is not greater than or equal to 6, the raw materials of the zirconium powder in each layer may be proportioned as follows:

[0036] In terms of mass percentage, the zirconium powder in the first layer includes 86%-90% of the white zirconium powder, 8%-12% of the yellow zirconium powder, 0.8%-1.2% of the red zirconium powder and 0.8%-1.2% of the gray zirconium powder; the zirconium powder in the second layer includes 88%-92% of the white zirconium powder, 7%-11% of the yellow zirconium powder, 0.3%-0.7% of the red zirconium powder and 0.3%-0.7% of the gray zirconium powder; the zirconium powder in the third layer includes 90%-94% of the white zirconium powder, 5.5%-9.5% of the yellow zirconium powder, 0.15%-0.35% of the red zirconium powder and 0.15%-0.35% of the gray zirconium powder; the zirconium powder in the fourth layer includes 86%-90% of the white zirconium powder, 8%-12% of the yellow zirconium powder, 0.8%-1.2% of the red zirconium powder and 0.8%-1.2% of the gray zirconium powder; the zirconium powder in the fourth layer includes 88%-92% of the white zirconium powder, 7%-11% of the yellow zirconium powder, 0.3%-0.7% of the red zirconium powder and 0.3%-0.7% of the gray zirconium powder. The zirconium powder comprises 92%-96% of the white zirconium powder, 3.7%-7.7% of the yellow zirconium powder, 0.1%-0.2% of the red zirconium powder and 0.1%-0.2% of the gray zirconium powder; the zirconium powder in the fifth layer comprises 94%-98% of the white zirconium powder, 1.8%-5.8% of the yellow zirconium powder, 0.05%-0.15% of the red zirconium powder and 0.005%-0.15% of the gray zirconium powder; the zirconium powder in the sixth layer comprises 96.5%-99.5% of the white zirconium powder, 0.4%-2.4% of the yellow zirconium powder, 0.03%-0.07% of the red zirconium powder and 0.03%-0.07% of the gray zirconium powder.

[0037] When providing zirconium powders of the first to nth layers, the zirconium powders of each layer can be mixed separately, and after mixing, each layer of powder can be passed through a 40-80 mesh sieve, and the sieved material can be taken as the required powder; preferably, the sieve can be passed through a 60 mesh sieve.

[0038] S2, stack the zirconium powders from the 1st layer to the nth layer from bottom to top in sequence to obtain a stacked product. Wherein, after stacking each layer of the zirconium powder, a pre-pressure is applied to the zirconium powder in the axial direction; that is, after stacking the 1st layer of the zirconium powder, the pre-pressure is applied to the zirconium powder in the axial direction, and after stacking the 2nd layer of the zirconium powder, the pre-pressure is also applied to the zirconium powder in the axial direction, and so on, until the nth layer of the zirconium powder is stacked, the pre-pressure is still applied to the zirconium powder in the axial direction; the pre-pressure can be transmitted through a push box, which is a material spreading mechanism used when stacking the zirconium powder and can contact the upper surface of the zirconium powder. In the present invention, the pre-pressure applied in the axial direction can be: the pre-pressure is applied downward from the upper surface of the zirconium powder.

[0039] It should be noted that by stacking the zirconium powder from the first layer to the nth layer, a gradual change in color and intensity can be ensured; the stacking is performed in the mold (mold cavity). In the present invention, when stacking the zirconium powder from the first layer to the nth layer, the pre-pressure is 1-5MPa, and the application time of the pre-pressure is 3-10s; further, the pre-pressure is 2-5MPa, and the application time of the pre-pressure is 4-6s.

[0040] S3, subjecting the superimposed product to a first compression, and subjecting it to a first pressure-holding treatment after the first compression, to obtain a first compressed body; subjecting the first compressed body to a second compression, and subjecting it to a second pressure-holding treatment after the second compression, to obtain a second compressed body; subjecting the second compressed body to a bidirectional counter-compression along the axial direction, and subjecting it to a bidirectional pressure-holding treatment after the bidirectional counter-compression, to obtain a first blank.

[0041] In the present invention, the pressure of the first pressure-holding treatment is 1-5MPa or 2-4MPa, and the duration is 1-10s or 4-6s; the pressure of the second pressure-holding treatment is 6-10MPa or 7-9MPa, and the duration is 1-10s or 4-6s; the total pressure of the bidirectional pressure-holding treatment is 25-60MPa or 40-60MPa, and the duration of the bidirectional pressure-holding treatment is 5-15s or 9-11s; during the bidirectional pressure-holding treatment, the pressure in the two directions remains consistent. It should be noted that although the present invention requires multiple compressions, multiple compressions must be combined with pressure holding to achieve the technical effects of the present invention.

[0042] As a further explanation of the first compression, the second compression and the bidirectional pressing; the direction of the first compression is downward, the rate can be 4-6mm / s, and when the pressure generated by the first compression reaches the pressure of the first pressure holding treatment, the first pressure holding treatment is performed; before performing the second compression, the upper punch is raised, the direction of the second compression is downward, the rate can be 4-6mm / s, and when the pressure generated by the second compression reaches the pressure of the second pressure holding treatment, the second pressure holding treatment is performed; the direction of the bidirectional pressing is up and down, the rate can be 4-6mm / s, and when the total pressure generated by the bidirectional pressing reaches the total pressure of the bidirectional pressure holding treatment, the bidirectional pressure holding treatment is performed.

[0043] After the bidirectional pressing is completed, the first green body can be demoulded under the protection of oleic acid. In order to make demoulding smoother and reduce the tensile stress during demoulding, the first green body needs to be demoulded under the protection of oleic acid; the specific process can be to use a brush to apply a layer of oleic acid coating on the mold surface before pressing to form an oil film between the powder and the mold.

[0044] Furthermore, when mixing the zirconium powder of each layer, the oleic acid can be mixed with the zirconium powder of each layer to wrap the oleic acid on the surface of the powder, thereby avoiding the situation where the oleic acid is missing when the mold is in use; and the oleic acid is directly mixed with the zirconium powder to ensure the performance of the green body and ceramics; when the oleic acid is mixed with the zirconium powder, the ratio of 10 kg of the zirconium powder to 30-70 mL of the oleic acid can be implemented.

[0045] S4, performing cold isostatic pressing on the first green body to obtain a second green body.

[0046] The pressure of the cold isostatic pressing treatment can be 200-280 MPa, and the holding time can be 100-200 seconds.

[0047] S5, calcining the second green body to obtain a green body of a multi-layer zirconia ceramic.

[0048] The temperature of the calcination treatment may be 900-1100° C., and the duration of the calcination treatment may be 1-6 hours.

[0049] The present invention also provides a green blank of multilayer zirconia ceramics, which is prepared by any of the green blank preparation methods described above.

[0050] The present invention also provides a method for preparing a multilayer zirconia ceramic, comprising: preparing a blank of the multilayer zirconia ceramic by any of the blank preparation methods described above, and then sequentially machining and sintering the blank to obtain the multilayer zirconia ceramic; wherein the sintering temperature can be 1450-1550°C, and the sintering time can be 1-5h.

[0051] The present invention also provides a multilayer zirconia ceramic, which is prepared by any of the above-mentioned methods for preparing the multilayer zirconia ceramic.

[0052] The present invention also provides a use of any of the above-described green blanks or any of the above-described multi-layer zirconia ceramics in dentures.

[0053] The following are specific examples of the present invention:

[0054] Example 1

[0055] 1. The preparation steps of six-layer zirconia ceramics are as follows:

[0056] 1. Provide zirconium powder required for 6 layers of powder;

[0057] In terms of mass percentage, the first layer of zirconium powder consists of 88% white zirconium powder, 10% yellow zirconium powder, 1% red zirconium powder and 1% gray zirconium powder;

[0058] The second layer of zirconium powder consists of 90% white zirconium powder, 9% yellow zirconium powder, 0.5% red zirconium powder and 0.5% grey zirconium powder;

[0059] The third layer of zirconium powder consists of 92% white zirconium powder, 7.5% yellow zirconium powder, 0.25% red zirconium powder and 0.25% gray zirconium powder;

[0060] The fourth layer of zirconium powder consists of 94% white zirconium powder, 5.7% yellow zirconium powder, 0.15% red zirconium powder and 0.15% gray zirconium powder;

[0061] The fifth layer of zirconium powder consists of 96% white zirconium powder, 3.8% yellow zirconium powder, 0.1% red zirconium powder and 0.1% gray zirconium powder;

[0062] The sixth layer of zirconium powder consists of 98% white zirconium powder, 1.9% yellow zirconium powder, 0.05% red zirconium powder and 0.05% gray zirconium powder.

[0063] Each layer of powder is mixed separately at a speed of 365 rpm for 30 minutes. After the mixing is completed, each layer of powder is sieved through a 60-mesh sieve separately.

[0064] In this embodiment, all colors of zirconium powder are derived from Shandong Guoci Functional Materials Co., Ltd.; in terms of mass percentage, white zirconium powder is composed of 92.5% ZrO2, 5% Y2O3, 2% HfO2, and 0.5% Al2O3; yellow zirconium powder is composed of 90% ZrO2, 7% Y2O3, 2% HfO2, 0.5% Al2O3, and 0.5% Fe2O3; red zirconium powder is composed of 90% ZrO2, 7% Y2O3, 2% HfO2, 0.5% Al2O3, and 0.5% Er2O3; gray zirconium powder is composed of 90% ZrO2, 7% Y2O3, 1.5% HfO2, 1% Al2O3, and 0.5% MnO.

[0065] 2. Stack the zirconium powders of the first to sixth layers in a mold (the diameter of the mold is 102 mm) from bottom to top to obtain a stacked product; in this embodiment, the thickness of the stacked product is 20 mm.

[0066] In this embodiment, the stacking process is: adding the first layer of zirconium powder to the sixth layer of zirconium powder into the mold cavity from bottom to top in sequence through the push box; for the first layer to the sixth layer of zirconium powder, immediately after adding each layer of zirconium powder, a pressure of 3Mpa is applied downward to the upper surface of the zirconium powder for 5s (applied through the push box; when the push box applies the 3Mpa pressure, the upper surface of the zirconium powder is covered).

[0067] 3. Press the superimposed product to obtain the first green body.

[0068] The pressing process is as follows: the upper punch is controlled to press the superimposed product downward at a rate of 5 mm / s, and when the pressure reaches 3 MPa, the pressure is maintained at 3 MPa for 5 seconds to obtain a first compressed body, and the thickness of the first compressed body is 18.5 mm;

[0069] After the pressure holding is completed, the upper punch is controlled to be raised by 10 mm. After being raised, the upper punch is controlled to press down the first compression body at a rate of 5 mm / s, and when the pressure reaches 8 MPa, the pressure is maintained at 8 MPa for 5 seconds to obtain a second compression body. In this embodiment, the thickness of the second compression body is 17 mm.

[0070] After the pressure holding is completed, the upper punch and the lower punch are controlled to perform bidirectional pressure (up and down directions) on the second compression body at a rate of 0.5 mm / s, and when the total pressure reaches 50 MPa, the bidirectional pressure is maintained for 10 seconds at a total pressure of 50 MPa to obtain the first blank; in this embodiment, the thickness of the first blank is 15.5 mm; during bidirectional pressure and bidirectional pressure holding, the pressure in the up and down directions remains consistent.

[0071] After the pressing process is completed, the first green body is demolded under the protection of oleic acid; the protection of oleic acid is specifically: before the zirconium powder is stacked on the mold, oleic acid is pre-attached to the mold surface to form an oil film between the powder and the mold to reduce friction.

[0072] 4. Perform cold isostatic pressing on the first embryo to obtain a second embryo; wherein the cold isostatic pressing pressure is 240 MPa and the duration is 120 seconds.

[0073] 5. Firing the second body to obtain a multi-layer zirconia ceramic blank; wherein the calcination is carried out in a muffle furnace, the calcination temperature is 1050°C, the holding time is 2h, the heating rate is 10°C / min, and the cooling rate is 20°C / min.

[0074] 6. After the green blank is cut by CAD / CAM, it is sintered in a muffle furnace to obtain a multi-layer zirconia ceramic; the sintering temperature is 1500°C, the sintering holding time is 2h, the heating rate of the sintering is 10°C / min, and the cooling rate of the sintering is 20°C / min.

[0075] 2. Test results:

[0076] 1. In this embodiment, the average density of the first green body (in the present invention, it refers to the first green body after demolding) is 2.42 g / cm 3 The average deformation is 0.14mm.

[0077] In this embodiment, the detection results of the first blank are shown in the following table:

[0078] <![CDATA[Density g / cm 3 > Deformation / mm 2.43 0.15 2.42 0.12 2.42 0.13 2.41 0.14 2.42 0.15

[0079] 2. In this embodiment, the average density of the blank is 3.11 g / cm 3 The average deformation is 0.21mm.

[0080] In this embodiment, the test results for the blank are shown in the following table:

[0081] <![CDATA[Density g / cm 3 > Deformation / mm 3.11 0.20 3.10 0.21 3.11 0.22 3.10 0.21 3.12 0.22

[0082] 3. In this embodiment, the average flexural strength of the multilayer zirconia ceramic is 1030 MPa, and the average hardness is 1626 hv.

[0083] In this embodiment, the test results of the multilayer zirconia ceramics are shown in the following table:

[0084] Flexural strengthMpa Hardness hv / 5kg 1000 1600 1050 1650 1030 1630 1020 1620 1050 1630

[0085] Comparative Example 1

[0086] 1. Compared with Example 1, the pressing process in step 3 was adjusted in this comparative example (the intermediate pressure holding process was omitted), and other conditions remained unchanged.

[0087] In this comparative example, the pressing process is: controlling the upper punch to press down the superimposed product at a rate of 5 mm / s, and stopping when the pressure reaches 3 MPa, to obtain a first compressed body;

[0088] The upper punch is controlled to be raised by 10 mm. After being raised, the upper punch is controlled to press down the first compression body at a rate of 5 mm / s, and stops when the pressure reaches 8 MPa, thereby obtaining a second compression body.

[0089] The upper punch and the lower punch are controlled to perform bidirectional pressing (up and down directions) on the second compression body at a rate of 0.5 mm / s, and when the total pressure reaches 50 MPa, the bidirectional pressure is maintained for 10 seconds at a total pressure of 50 MPa to obtain the first blank. The thickness of the first blank is 15.5 mm. During bidirectional pressing and bidirectional pressure maintenance, the pressure in the up and down directions is kept consistent.

[0090] 2. Test results:

[0091] 1. In this comparative example, after reducing the intermediate pressure holding process, the average density of the first green body is 2.39g / cm 3 The average deformation is 0.20mm.

[0092] In this comparative example, the test results for the first blank are shown in the following table:

[0093] <![CDATA[Density g / cm 3 > Deformation / mm 2.38 0.21 2.40 0.22 2.39 0.21 2.40 0.19 2.40 0.19

[0094] 2. In this comparative example, after reducing the intermediate pressure holding process, the average density of the green billet is 3.10g / cm 3 The average deformation is 0.31 / mm.

[0095] In this comparative example, the test results for the blank are shown in the following table:

[0096]

[0097]

[0098] 3. In this comparative example, the average flexural strength of the multilayer zirconia ceramic is 896 MPa, and the average hardness is 1608.4 hv.

[0099] In this comparative example, the test results of the multilayer zirconia ceramics are shown in the following table:

[0100] Flexural strengthMpa Hardness hv / 5kg 800 1610 850 1600 900 1620 1010 1602 920 1610

[0101] Comparative Example 2

[0102] 1. Compared with Example 1, the pressing process in step 3 of this comparative example was adjusted, and other conditions remained unchanged.

[0103] In this comparative example, the pressing process is: controlling the upper punch to press down the superimposed product at a rate of 5 mm / s, and when the pressure reaches 3 MPa, maintaining the pressure at 3 MPa for 5 seconds to obtain a first compressed body;

[0104] After the pressure holding is completed, the upper punch is controlled to be raised by 10 mm. After being raised, the upper punch is controlled to press down the first compression body at a rate of 5 mm / s, and when the pressure reaches 8 MPa, the pressure is maintained at 8 MPa for 5 seconds to obtain the second compression body;

[0105] After the pressure holding is completed, the upper punch and the lower punch are controlled to perform bidirectional pressure (up and down directions) on the second compression body at a rate of 0.5 mm / s, and when the total pressure reaches 20 MPa, the bidirectional pressure is maintained for 10 seconds at a total pressure of 20 MPa to obtain the first blank. The thickness of the first blank is 16 mm. During bidirectional pressure and bidirectional pressure holding, the pressure in the up and down directions remains consistent.

[0106] 2. Test results:

[0107] 1. In this comparative example, the average density of the first green body is 2.31 g / cm 3 The average deformation is 0.21mm.

[0108] In this comparative example, the test results for the first blank are shown in the following table:

[0109] <![CDATA[Density g / cm 3 > Deformation / mm 2.31 0.21 2.32 0.21 2.34 0.21 2.30 0.22 2.30 0.19

[0110] 2. In this comparative example, the average density of the green blank is 3.10 g / cm 3 The average deformation is 0.40mm.

[0111] In this comparative example, the test results for the blank are shown in the following table:

[0112] <![CDATA[Density g / cm 3 > Deformation / mm 3.10 0.38 3.10 0.41 3.11 0.42 3.11 0.39 3.08 0.40

[0113] 3. In this comparative example, the average flexural strength of the multilayer zirconia ceramic is 892 MPa, and the average hardness is 1600 hv.

[0114] In this comparative example, the test results of the multilayer zirconia ceramics are shown in the following table:

[0115] Flexural strengthMpa Hardness hv / 5kg 810 1600 820 1580 900 1610 1010 1610 920 1600

[0116] Comparative Example 3

[0117] 1. Compared with Example 1, the oleic acid protection was omitted in the demoulding process of this comparative example, and other conditions remained unchanged.

[0118] 2. Test results:

[0119] 1. In this comparative example, the average density of the first body is 2.41 g / cm 3 The average deformation is 0.27mm.

[0120] In this comparative example, the test results for the first blank are shown in the following table:

[0121] <![CDATA[Density g / cm 3 > Deformation / mm 2.41 0.25 2.42 0.27 2.41 0.28 2.40 0.26 2.41 0.29

[0122] 2. In this comparative example, the average density of the green blank is 3.10 g / cm 3 The average deformation is 0.39mm.

[0123] In this comparative example, the test results for the blank are shown in the following table:

[0124] <![CDATA[Density g / cm 3 > Deformation / mm 3.11 0.35 3.10 0.41 3.11 0.42 3.09 0.38 3.10 0.37

[0125] 3. In this comparative example, the average flexural strength of the multilayer zirconia ceramic is 912 MPa, and the average hardness is 1604.4 hv.

[0126] In this comparative example, the test results of the multilayer zirconia ceramics are shown in the following table:

[0127]

[0128]

[0129] Comparative Example 4

[0130] 1. Compared with Example 1, this comparative example replaces the oleic acid protection in the demoulding process with anhydrous ethanol, and other conditions remain unchanged.

[0131] 2. Test results:

[0132] 1. In this comparative example, the average density of the first body is 2.41 g / cm 3 The average deformation is 0.18mm.

[0133] In this comparative example, the test results for the first blank are shown in the following table:

[0134] <![CDATA[Density g / cm 3 > Deformation / mm 2.41 0.17 2.41 0.17 2.42 0.17 2.40 0.19 2.41 0.20

[0135] 2. In this comparative example, the average density of the green blank is 3.09 g / cm 3 The average deformation is 0.24mm.

[0136] In this comparative example, the test results for the blank are shown in the following table:

[0137] <![CDATA[Density g / cm 3 > Deformation / mm 3.07 0.25 3.08 0.27 3.11 0.22 3.10 0.22 3.10 0.23

[0138] 3. In this comparative example, the average flexural strength of the multilayer zirconia ceramic is 1006 MPa, and the average hardness is 1610.4 hv.

[0139] In this comparative example, the test results of the multilayer zirconia ceramics are shown in the following table:

[0140] Flexural strengthMpa Hardness hv / 5kg 980 1620 1000 1600 990 1620 1010 1602 1050 1610

[0141] Comparative Example 5

[0142] 1. Compared with Example 1, the pressing process in step 3 of this comparative example was adjusted, and other conditions remained unchanged.

[0143] In this comparative example, the pressing process is: control the upper punch and the lower punch to perform bidirectional pressing (up and down directions) on the superimposed products at a rate of 0.5 mm / s, and when the total pressure reaches 50 MPa, bidirectional pressure is maintained for 10 seconds at a total pressure of 50 MPa to obtain the first blank, and the thickness of the first blank is 15.5 mm; during bidirectional pressing and bidirectional pressure maintenance, the pressure in the up and down directions is kept consistent.

[0144] 2. Test results:

[0145] 1. In this comparative example, the average density of the first green body is 2.40 g / cm 3 The average deformation is 0.22mm.

[0146] In this comparative example, the test results for the first blank are shown in the following table:

[0147] <![CDATA[Density g / cm 3 > Deformation / mm 2.40 0.21 2.40 0.22 2.40 0.23 2.39 0.25 2.41 0.20

[0148] 2. In this comparative example, the average density of the green blank is 3.09 g / cm 3 The average deformation is 0.30mm.

[0149] In this comparative example, the test results for the blank are shown in the following table:

[0150] <![CDATA[Density g / cm 3 > Deformation / mm 3.09 0.31 3.08 0.32 3.10 0.32 3.10 0.29 3.08 0.28

[0151] 3. In this comparative example, the average flexural strength of the multilayer zirconia ceramic is 928 MPa, and the average hardness is 1614 hv.

[0152] In this comparative example, the test results of the multilayer zirconia ceramics are shown in the following table:

[0153] Flexural strengthMpa Hardness hv / 5kg 910 1610 920 1622 920 1618 930 1607 960 1613

[0154] Comparative Example 6

[0155] 1. Compared with Example 1, the superposition process in step 2 of this comparative example is adjusted, and other conditions remain unchanged.

[0156] In this comparative example, the stacking process is: adding the first layer of zirconium powder to the sixth layer of zirconium powder into the mold cavity from bottom to top in sequence through the push box; for the first layer to the sixth layer of zirconium powder, after each layer of zirconium powder is added, a pressure of 3Mpa is immediately applied downward to the upper surface of the zirconium powder for 1s (applied by the push box).

[0157] 2. Test results:

[0158] 1. In this comparative example, the average density of the first body is 2.41 g / cm 3 The average deformation is 0.25mm.

[0159] In this comparative example, the test results for the first blank are shown in the following table:

[0160] <![CDATA[Density g / cm 3 > Deformation / mm 2.41 0.24 2.40 0.26 2.41 0.25 2.41 0.25 2.42 0.25

[0161] 2. In this comparative example, the average density of the green blank is 3.10 g / cm 3 The average deformation is 0.35mm.

[0162] In this comparative example, the test results for the blank are shown in the following table:

[0163] <![CDATA[Density g / cm 3 > Deformation / mm 3.10 0.36 3.08 0.35 3.10 0.36 3.10 0.34 3.12 0.35

[0164] 3. In this comparative example, the average flexural strength of the multilayer zirconia ceramic is 926 MPa, and the average hardness is 1612 hv.

[0165] In this comparative example, the test results of the multilayer zirconia ceramics are shown in the following table:

[0166]

[0167]

[0168] Example 2

[0169] 1. Compared with Example 1, the pressing process in step 3 of this embodiment is adjusted, and other conditions remain unchanged.

[0170] In this embodiment, the pressing process is: controlling the upper punch to press down the superimposed product at a rate of 5 mm / s, and when the pressure reaches 3 MPa, maintaining the pressure at 3 MPa for 5 seconds to obtain a first compressed body;

[0171] After the pressure holding is completed, the upper punch is controlled to be raised by 10 mm. After being raised, the upper punch is controlled to press down the first compression body at a rate of 5 mm / s, and when the pressure reaches 8 MPa, the pressure is maintained at 8 MPa for 5 seconds to obtain the second compression body;

[0172] After the pressure holding is completed, the upper punch and the lower punch are controlled to perform bidirectional pressure (up and down directions) on the second compression body at a rate of 0.5 mm / s, and when the total pressure reaches 30 MPa, the bidirectional pressure is maintained for 10 seconds at a total pressure of 30 MPa to obtain the first blank. The thickness of the first blank is 16 mm. During bidirectional pressure and bidirectional pressure holding, the pressure in the up and down directions remains consistent.

[0173] 2. Test results:

[0174] 1. In this embodiment, the average density of the first green body is 2.31 g / cm 3 The average deformation is 0.11mm.

[0175] In this embodiment, the detection results of the first blank are shown in the following table:

[0176] <![CDATA[Density g / cm 3 > Deformation / mm 2.31 0.11 2.32 0.11 2.30 0.12 2.31 0.12 2.32 0.11

[0177] 2. In this embodiment, the average density of the blank is 3.10 g / cm 3 The average deformation is 0.20mm.

[0178] In this embodiment, the test results for the blank are shown in the following table:

[0179] <![CDATA[Density g / cm 3 > Deformation / mm 3.10 0.20 3.10 0.21 3.11 0.21 3.10 0.20 3.09 0.20

[0180] 3. In this embodiment, the average flexural strength of the multilayer zirconia ceramic is 1030 MPa, and the average hardness is 1605 HV.

[0181] In this embodiment, the test results of the multilayer zirconia ceramics are shown in the following table:

[0182] Flexural strengthMpa Hardness hv / 5kg 1020 1600 1040 1600 1030 1610 1040 1605 1020 1610

[0183] Example 3

[0184] 1. Compared with Example 1, the oleic acid protection process in this example is adjusted, and other conditions remain unchanged.

[0185] In this embodiment, the process of oleic acid protection is as follows: when mixing materials, oleic acid and zirconium powder are mixed together, and 10 kg of zirconium powder is matched with 50 mL of oleic acid.

[0186] 2. Test results:

[0187] 1. In this embodiment, the average density of the first green body is 2.41 g / cm 3 The average deformation is 0.15mm.

[0188] In this embodiment, the detection results of the first blank are shown in the following table:

[0189] <![CDATA[Density g / cm 3 > Deformation / mm 2.41 0.14 2.42 0.16 2.40 0.15 2.41 0.15 2.42 0.15

[0190] 2. In this embodiment, the average density of the blank is 3.10 g / cm 3 The average deformation is 0.19mm.

[0191] In this embodiment, the test results for the blank are shown in the following table:

[0192] <![CDATA[Density g / cm 3 > Deformation / mm 3.10 0.19 3.10 0.20 3.11 0.18 3.10 0.20 3.11 0.18

[0193] 3. In this embodiment, the average flexural strength of the multilayer zirconia ceramic is 1024 MPa, and the average hardness is 1612 HV.

[0194] In this embodiment, the test results of the multilayer zirconia ceramics are shown in the following table:

[0195] Flexural strengthMpa Hardness hv / 5kg 1030 1621 1020 1600 1020 1621 1030 1601 1020 1617

[0196] The above technical solutions of the present invention are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention specification under the technical concept of the present invention, or directly / indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method for preparing a green body of a multilayer zirconia ceramic, characterized in that: Includes steps: S1, providing zirconium powder of the first to nth layers, where n is an integer not less than 2; S2, stacking the zirconium powders from the first layer to the nth layer from bottom to top, and applying a pre-pressure to the zirconium powders along the axial direction after stacking each layer of the zirconium powders, to obtain a stacked product; S3, performing a first compression on the superimposed product, and performing a first pressure holding treatment after the first compression to obtain a first compressed body; performing a second compression on the first compressed body, and performing a second pressure holding treatment after the second compression to obtain a second compressed body; performing a bidirectional counter-compression on the second compressed body along the axial direction, and performing a bidirectional pressure holding treatment after the bidirectional counter-compression to obtain a first blank; S4, performing cold isostatic pressing on the first green body to obtain a second green body; S5, calcining the second green body to obtain a green body of a multi-layer zirconia ceramic.

2. The method for preparing a raw embryo according to claim 1, characterized in that: The zirconium powder in each layer contains white zirconium powder, yellow zirconium powder, red zirconium powder and gray zirconium powder; by weight percentage, The white zirconium powder includes 91.5-93.5% ZrO2, 4-6% Y2O3, 1-3% HfO2, and 0.3-0.7% Al2O3; the yellow zirconium powder includes 89-91% ZrO2, 6-8% Y2O3, 1-3% HfO2, 0.3-0.7% Al2O3, and 0.3-0.7% Fe2O3; the red zirconium powder includes 89-91% ZrO2, 6-8% Y2O3, 1-3% HfO2, 0.3-0.7% Al2O3, and 0.3-0.7% Er2O3; the gray zirconium powder includes 88-91% ZrO2, 6-8% Y2O3, 1-2% HfO2, 0.5-1.5% Al2O3, and 0.3-0.7% MnO.

3. The method for preparing the embryo according to claim 2, characterized in that: In the zirconium powder from the first layer to the nth layer, the mass proportion of the white zirconium powder increases successively, and the mass proportions of the yellow zirconium powder, the red zirconium powder and the gray zirconium powder decrease successively.

4. The method for preparing a raw embryo according to claim 1, characterized in that: The pre-pressure is 1-5 MPa, and the application time of the pre-pressure is 3-10 s; The pressure of the first pressure-maintaining treatment is 1-5 MPa, and the duration is 1-10 s; The pressure of the second pressure-maintaining treatment is 6-10 MPa, and the duration is 1-10 s; The total pressure of the bidirectional pressure-maintaining treatment is 25-60 MPa, and the duration of the bidirectional pressure-maintaining treatment is 5-15 s; The stacking is performed in a mold, and the step S3 further comprises: demolding the first green body under the protection of oleic acid.

5. The method for preparing a raw embryo according to any one of claims 1 to 4, characterized in that: The cold isostatic pressing treatment is performed at a pressure of 200-280 MPa and a holding time of 100-200 s; The temperature of the calcination treatment is 900-1100° C., and the heat preservation time of the calcination treatment is 1-6 hours.

6. A green body of a multilayer zirconia ceramic, characterized in that: The green billet is prepared by the green billet preparation method as described in any one of claims 1 to 5.

7. A method for preparing a multilayer zirconia ceramic, characterized in that: include: A green blank of a multilayer zirconia ceramic is prepared by the green blank preparation method according to any one of claims 1 to 5, and then the green blank is subjected to mechanical processing and sintering treatment in sequence to obtain the multilayer zirconia ceramic.

8. The method for preparing the multilayer zirconia ceramic according to claim 7, characterized in that: The temperature of the sintering treatment is 1450-1550° C., and the heat preservation time of the sintering treatment is 1-5 hours.

9. A multilayer zirconia ceramic, characterized in that: The multilayer zirconia ceramic is prepared by the preparation method according to claim 7 or 8.

10. Use of the green blank as claimed in claim 6 or the multilayer zirconia ceramic as claimed in claim 9 in dentures.

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