Preparation method of zirconia bicolor ceramic co-fired

Abstract

The application relates to the technical field of ceramic materials, and discloses a preparation method of zirconia bicolor ceramic co-firing, which comprises the following steps: adjusting a powder formula, twice press forming by using red and black zirconia, cold isostatic pressing forming, air sintering, hot isostatic pressing sintering, reduction sintering and the like, so that the performance of the red product can be guaranteed, the consistency and stability of the color of the black product can be maintained, a bicolor zirconia ceramic product with diversified colors, high performance and good color consistency is prepared, the product has a good market application prospect, and the multiple requirements of different customers can be met.

Description

Technical Field

[0001] This invention relates to the field of ceramic materials technology, and in particular to a method for preparing zirconia bicolor ceramics by co-firing. Background Technology

[0002] Zirconia (chemical formula ZrO2), as a cutting-edge novel ceramic material, exhibits excellent electrical conductivity, significant thermal expansion performance, extremely low coefficient of friction, unparalleled chemical stability, and outstanding resistance to corrosion and erosion. Among numerous ceramic materials, zirconium oxide stands out due to its superior high-temperature stability, excellent thermal insulation performance, extremely low thermal conductivity, and thermal expansion coefficient similar to that of metals. Particularly noteworthy is the unique martensitic phase transformation characteristic of zirconium oxide, making it a highly outstanding reinforcing agent in the field of composite materials. Furthermore, zirconium oxide possesses a high refractive index, a characteristic that provides limitless possibilities for the preparation of colored, translucent polycrystalline materials. These materials can not only present a dazzling and colorful appearance like natural gemstones but also display a vibrant and multicolored charm, like gemstone jewelry, thus demonstrating extremely broad application potential in the current market.

[0003] However, for conventional zirconia ceramic materials currently on the market, the main sintering method is still limited to air sintering, and the product color is limited to pure black or pure white. The preparation process of black zirconia products mainly relies on two approaches: one is to pre-mix white zirconia powder with colorant and then shape and sinter it; the other is to convert white zirconia products into black through a vacuum blackening sintering process. However, the blackening process has high requirements for temperature field and furnace equipment, and it is difficult to guarantee the color consistency of the product; while using ordinary colorant addition, after multiple high-temperature reaction sinterings, the color is prone to cross-coloring and volatilization, thus affecting the final quality of the product.

[0004] Therefore, improving and upgrading existing zirconia ceramic material preparation technologies has become an urgent task.

[0005] The above information is provided as background information only to aid in understanding this disclosure and does not constitute an assertion or admission that any of the above content can be used as prior art relative to this disclosure. Summary of the Invention

[0006] This invention provides a method for preparing zirconia bicolor ceramics by co-firing, in order to solve the problems existing in the prior art.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A method for co-firing zirconia bicolor ceramics, the method comprising:

[0009] The red granulated powder and the black granulated powder are pressed into shape in a single press within a conforming steel mold. The red granulated powder comprises the following components by weight percentage: 92%-93% zirconium oxide, 3%-5% red colorant, and 2.5% stabilizer. The black granulated powder comprises the following components by weight percentage: 92%-93% zirconium oxide, 5% black colorant, and 2.5% stabilizer.

[0010] The green blanks, after being pressed and shaped once, are placed into a molding die and pressed and shaped a second time.

[0011] The green body after secondary pressing is then subjected to cold isostatic pressing.

[0012] After cold isostatic pressing, the blank is debonded and pre-fired; then, it is sintered at high temperature in air atmosphere to obtain a first-fired blank.

[0013] The first-fired blank is hot isostatically sintered in an inert atmosphere; subsequently, it is reduced sintered at high temperature in a reducing atmosphere to obtain a three-sintered bicolor ceramic blank.

[0014] The bicolor ceramic blank is then precision machined to obtain a zirconia ceramic part.

[0015] Furthermore, in the method for preparing zirconia bicolor ceramics by co-firing, the red colorant is cerium oxide.

[0016] Furthermore, in the method for preparing zirconia bicolor ceramics by co-firing, the black colorant comprises iron, chromium, and nickel in a mass ratio of 2:2:1.

[0017] Furthermore, in the method for preparing zirconia bicolor ceramics by co-firing, the specifications of the red granulated powder and the black granulated powder are as follows:

[0018] D50 is 0.1-0.3μm, flowability is 45-55S, loose density is 1.25-1.45g / cm3, and powder shrinkage rate is 20%-21%.

[0019] Furthermore, in the method for preparing zirconia bicolor ceramics by co-firing, the pressing pressure of the one-time pressing is 1T-3T, and the holding time is 2S.

[0020] Furthermore, in the method for preparing zirconia bicolor ceramics by co-firing, the pressing pressure of the secondary pressing is 30-35T, and the density of the green body after secondary pressing is 3.0±0.2g / cm3.

[0021] Furthermore, in the method for preparing zirconia bicolor ceramics by co-firing, the sintering temperature is 1420-1490℃ in an air atmosphere, the holding time is 1.5-2.5h, the heating rate is 3-4℃ / min, and the number of layers is 1-4.

[0022] Furthermore, in the method for preparing zirconia bicolor ceramics by co-firing, the hot isostatic pressing sintering temperature under an inert atmosphere is 1230-1350℃, and the holding time is 1-3h.

[0023] Furthermore, in the method for preparing zirconia bicolor ceramics by co-firing, the reduction sintering temperature is 1390-1430℃, and the holding time is 1-3h.

[0024] Furthermore, in the method for preparing zirconia bicolor ceramics by co-firing, the reducing atmosphere is a mixture of nitrogen and hydrogen.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] This invention provides a method for preparing bicolor zirconia ceramics through co-firing. By adjusting the powder formula, red and black zirconia are used for two-stage pressing and molding, and undergoing multiple sintering methods such as cold isostatic pressing, air sintering, hot isostatic pressing, and reduction sintering. This ensures the performance of the red product while maintaining the color consistency and stability of the black product, thereby producing bicolor zirconia ceramic parts with diverse colors, high performance, and good color consistency. This method has good market application prospects and can meet the diverse requirements of different customers.

[0027] The present invention has other features and advantages, which will be apparent from or will be set forth in detail in the accompanying drawings and the following detailed description, which together serve to explain the particular principles of the invention. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic flowchart of a method for preparing zirconia bicolor ceramics by co-firing according to an embodiment of the present invention;

[0030] Figure 2 This is a schematic diagram of a green blank formed by one-time pressing as mentioned in the embodiments of the present invention;

[0031] Figure 3 This is a schematic diagram of a green blank formed by one-time pressing as mentioned in the embodiments of the present invention;

[0032] Figure 4 This is a schematic diagram showing the two green embryos tightly bonded together after secondary pressing as mentioned in the embodiments of the present invention;

[0033] Figure 5 This is a schematic diagram of the zirconium oxide ceramic part mentioned in the embodiments of the present invention;

[0034] Figure 6 This is an image showing the effect of adjusting the color bleeding at the boundary line of the granulated powder before the process, as mentioned in the embodiments of the present invention.

[0035] Figure 7 This is an image showing the effect of improving the color bleeding at the boundary line after adjusting the granulated powder, as mentioned in the embodiments of the present invention. Detailed Implementation

[0036] To illustrate the possible application scenarios, technical principles, implementable specific solutions, and achievable objectives and effects of this application in detail, the following description, in conjunction with the listed specific embodiments and accompanying drawings, provides a detailed explanation. The embodiments described herein are merely illustrative of the technical solutions of this application and are therefore intended to limit the scope of protection of this application.

[0037] In this document, the term "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The term "embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment, nor does it specifically limit its independence or connection with other embodiments. In principle, in this application, as long as there are no technical contradictions or conflicts, the technical features mentioned in each embodiment can be combined in any way to form corresponding implementable technical solutions.

[0038] Unless otherwise defined, the technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the use of related terms herein is merely for the purpose of describing particular embodiments and is not intended to limit this application.

[0039] In the description of this application, the term "and / or" is used to describe the logical relationship between objects, indicating that three relationships can exist. For example, A and / or B means: A exists, B exists, and A and B exist simultaneously. Additionally, the character " / " in this document generally indicates that the preceding and following objects have an "or" logical relationship.

[0040] In this application, terms such as “first” and “second” are used only to distinguish one entity or operation from another, and do not necessarily require or imply any actual quantity, hierarchy or order relationship between these entities or operations.

[0041] Unless otherwise specified, the use of terms such as “comprising,” “including,” “having,” or other similar expressions in this application is intended to cover non-exclusive inclusion, which does not exclude the presence of additional elements in a process, method, or product that includes the stated elements, such that a process, method, or product that includes a list of elements may include not only those defined elements but also other elements not expressly listed, or elements inherent to such a process, method, or product.

[0042] In this application, expressions such as "greater than", "less than", and "exceeding" are understood to exclude the stated number; expressions such as "above", "below", and "within" are understood to include the stated number. Furthermore, in the description of the embodiments of this application, "multiple" means two or more (including two), and similar expressions related to "multiple" are also understood in this way, such as "multiple groups" and "multiple times", unless otherwise explicitly specified.

[0043] In the description of the embodiments of this application, the space-related expressions used, such as "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "vertical," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," indicate the orientation or positional relationship based on the orientation or positional relationship shown in the specific embodiments or drawings. They are only for the purpose of describing the specific embodiments of this application or for the reader's understanding, and do not indicate or imply that the device or component referred to must have a specific position, a specific orientation, or be constructed or operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0044] Unless otherwise expressly specified or limited, the terms "installation," "connection," "linking," "fixing," and "setting," as used in the description of the embodiments of this application, should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral setting; it can be a mechanical connection, an electrical connection, or a communication connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection of two components or the interaction between two components. For those skilled in the art to which this application pertains, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0045] Please refer to Figure 1 This is a schematic flowchart of a method for preparing zirconia two-color ceramic through co-firing according to Embodiment 1 of the present invention. This method is applicable to the preparation of zirconia ceramic parts, such as watch dials. The method specifically includes the following steps:

[0046] S101. The red granulated powder and the black granulated powder are pressed and formed in a single step in a conforming steel mold. The red granulated powder comprises the following components by weight percentage: 92%-93% zirconium oxide, 3%-5% red colorant, and 2.5% stabilizer. The black granulated powder comprises the following components by weight percentage: 92%-93% zirconium oxide, 5% black colorant, and 2.5% stabilizer.

[0047] It should be noted that this step involves placing the pre-prepared red and black granulating powders into their respective conforming steel molds for a single pressing process. During this process, it is ensured that the pressing pressure and green density of the two powders are similar to meet the process requirements. The conforming steel mold is designed based on a portion of the shape of the final product (such as a dial) to ensure that the green body formed in a single pressing has the required shape and size. Figure 2 and Figure 3 As shown.

[0048] In red granulated powder, zirconium oxide is the main material, providing ceramics with high hardness, high strength and wear resistance. Red colorant gives ceramics a red appearance, while stabilizer is used to improve the stability and sintering performance of the material.

[0049] In black granulated powder, the zirconium oxide and stabilizer are similar to those in red granulated powder, but the content of black colorant is relatively high to form a distinct black color.

[0050] In one embodiment of this example, the red colorant is cerium oxide.

[0051] It should be noted that cerium oxide, as a commonly used ceramic colorant, has good stability and high temperature resistance, can maintain a bright red color during high-temperature sintering, and has little impact on the properties of the zirconia matrix.

[0052] The black colorant comprises iron, chromium, and nickel in a mass ratio of 2:2:1. This combination provides a stable black effect and is not prone to color change during high-temperature sintering. Iron, chromium, and nickel are all common metallic elements, and their addition to ceramics can form stable compounds, thereby giving the ceramics a black appearance.

[0053] The specifications for both the red granulated powder and the black granulated powder are as follows:

[0054] D50 is 0.1-0.3μm, flowability is 45-55S, loose density is 1.25-1.45g / cm3, and powder shrinkage rate is 20%-21%.

[0055] It should be noted that D50 is an important parameter for measuring the particle size distribution of powder, indicating that 50% of the particles in the powder have a diameter smaller than this value. In this embodiment, the D50 of the granulated powder is controlled within the range of 0.1-0.3 μm, which helps to obtain uniform and fine ceramic products.

[0056] Flowability is an important indicator for measuring the flowability of powders, and it is usually measured using a Hall effect flowmeter. In this embodiment, the flowability of the granulated powder is controlled within the range of 45-55 seconds, which is beneficial for the uniform filling and pressing of the powder.

[0057] Bulk density refers to the density of powder in its natural packing state. In this embodiment, the bulk density of the granulated powder is controlled within the range of 1.25-1.45 g / cm³, which helps to obtain a higher green density during the pressing process.

[0058] Powder shrinkage rate refers to the proportion of volume shrinkage that occurs in powder due to high temperature during sintering. In this embodiment, the shrinkage rate of the granulated powder is controlled within the range of 20%-21%, which helps to obtain ceramic products with stable dimensions and regular shapes.

[0059] In summary, by carefully selecting the components of the red and black colorants and strictly controlling the key indicators of the granulated powder, this embodiment successfully prepared zirconia bicolor ceramic parts with excellent performance and stable color.

[0060] In one embodiment of this example, the pressing pressure for the one-time pressing is 1T-3T, and the holding time is 2S.

[0061] It is important to note that the pressing pressure directly affects the density and strength of the green body. Insufficient pressure may result in insufficient green body density, affecting densification and performance during subsequent sintering; excessive pressure may damage the mold or deform the green body. Therefore, selecting the appropriate pressing pressure is crucial for obtaining high-quality green bodies.

[0062] Holding time refers to the period of time during which the pressing pressure is maintained at a set value. The length of the holding time significantly affects the density distribution and uniformity of the green billet. Too short a holding time may lead to uneven density distribution within the green billet, affecting the performance of the final product; too long a holding time may increase production costs and reduce production efficiency. Therefore, selecting a reasonable holding time is crucial to ensuring the quality of the green billet.

[0063] In summary, by precisely controlling the pressing pressure and holding time during the single-stage pressing process, this embodiment can produce green bodies with uniform density and good strength, laying a solid foundation for subsequent sintering and processing. This optimization of process parameters not only helps improve product quality and performance but also reduces production costs and increases production efficiency.

[0064] S102. Place the green blanks that have been pressed and formed in one step into the mold and press them again.

[0065] It should be noted that this step involves placing the red and black green blanks, after the initial pressing, together into a larger molding die (such as a watch dial) for a second pressing. The purpose of this step is to tightly bond the two green blanks together, such as... Figure 4 As shown, this is in preparation for the subsequent co-firing process.

[0066] S103. The green body after secondary pressing is subjected to cold isostatic pressing.

[0067] It should be noted that this step involves cold isostatic pressing (COP) the combined green body after secondary pressing. COP is a technique that applies uniform pressure in a high-pressure liquid medium to improve the density and uniformity of the green body, reduce porosity, and thus improve the mechanical properties of the final product.

[0068] In one embodiment of this example, the pressing pressure of the secondary pressing is 30-35T, and the density of the green embryo after secondary pressing is 3.0±0.2g / cm3.

[0069] It should be noted that this pressure range is chosen based on the strength of the green body obtained from the first pressing and the required density and performance of the final product. Compared to the first pressing, the second pressing requires higher pressure to ensure a tight bond between the red and black green bodies and to further improve the overall density and strength of the green body. By precisely controlling the pressing pressure, it is possible to ensure that the green body can be uniformly densified during the subsequent sintering process, thereby obtaining a final product with excellent performance.

[0070] Green stock density is a crucial indicator of its densification level, directly impacting the performance of the final product. In this embodiment, by precisely controlling the process parameters of the secondary pressing molding, such as pressing pressure and holding time, the green stock density can be successfully controlled within a relatively narrow range. This density selection ensures both the stability and densification of the green stock during sintering, while avoiding sintering difficulties and increased costs caused by excessively high density.

[0071] In summary, by precisely controlling the pressing pressure and the density requirements of the green embryo during the secondary pressing process, this embodiment can produce a green embryo with a uniform and dense structure and good performance.

[0072] S104. The blank formed by cold isostatic pressing is debonded and pre-fired after debonding; then, it is sintered at high temperature in air atmosphere to obtain a first-fired blank.

[0073] It should be noted that after cold isostatic pressing, this step requires debinding the green body to remove the binder and other organic matter added during the pressing process. After debinding, a pre-firing process is performed, in which the green body is sintered at a lower temperature to further solidify its structure, improve its strength, prevent cracking, and remove residual moisture and gases. Subsequently, sintering is carried out in a high-temperature air atmosphere to obtain a first-firing green body, ensuring uniform color.

[0074] In one embodiment of this example, under an air atmosphere, the sintering temperature is 1420-1490℃, the holding time is 1.5-2.5h, the heating rate is 3-4℃ / min, and the number of layers is 1-4.

[0075] It should be noted that this temperature range is chosen based on the characteristics of the materials used and the performance requirements of the desired product. Within this temperature range, the material can undergo sufficient physicochemical reactions, thereby achieving densification and performance improvement. At the same time, avoiding excessively high sintering temperatures can reduce energy consumption and production costs, and prevent the material from deforming or cracking due to overheating.

[0076] The holding time significantly impacts material densification and grain growth. In this embodiment, precise control of the holding time ensures the material achieves the desired degree of densification during sintering, while preventing performance degradation due to excessive grain growth. The holding time setting also needs to consider production efficiency and cost factors to ensure efficient production while meeting product performance requirements.

[0077] The choice of heating rate affects the sintering process mainly in two aspects: first, it avoids excessive thermal stress caused by rapid heating, which could lead to cracking; second, it ensures that the material has sufficient time for preheating and uniform heating during the heating process, thereby achieving more uniform sintering. In this embodiment, by controlling the heating rate within a reasonable range, the stability and controllability of the sintering process can be ensured.

[0078] The number of layers directly affects the heat transfer efficiency and the uniformity of material heating within the sintering furnace. In this embodiment, by rationally controlling the number of layers, it can be ensured that each layer of material receives sufficient heat for sintering, while avoiding uneven heat transfer and incomplete sintering caused by too many layers. Furthermore, a reasonable number of layers also helps improve the utilization rate and production efficiency of the sintering furnace.

[0079] In summary, by precisely controlling process parameters such as sintering temperature, holding time, heating rate, and number of layers, this embodiment can produce ceramic products with excellent performance and uniform structure.

[0080] S105. The first-fired blank is hot isostatically sintered in an inert atmosphere; subsequently, it is reduced sintered at high temperature in a reducing atmosphere to obtain a three-sintered bicolor ceramic blank.

[0081] It should be noted that this step involves hot isostatic pressing (HIP) sintering of the first-fired ceramic blank under an inert atmosphere. HIP combines high temperature and high pressure, which helps to further improve the density and uniformity of the ceramic. Subsequently, high-temperature reduction sintering is performed under a reducing atmosphere. This step aims to stabilize the color of the ceramic. Under a reducing atmosphere, the colorant generally does not react, thus maintaining color stability and consistency. Standard samples tested with a colorimeter show that the black L value is consistently within the range of 3-4.

[0082] In one embodiment of this example, the temperature for hot isostatic pressing sintering under an inert atmosphere is 1230-1350℃, and the holding time is 1-3h.

[0083] It should be noted that this temperature range was chosen to ensure that the material can be fully densified under high pressure and an inert atmosphere, while avoiding excessively high temperatures that could damage the material structure or reduce its performance.

[0084] The duration of heat treatment has a significant impact on the densification degree and grain growth of materials. Within this time range, the material can fully undergo physicochemical reactions, achieving higher density and a more uniform structure. At the same time, a reasonable heat treatment time also helps improve production efficiency and reduce costs.

[0085] In one embodiment of this invention, the reducing atmosphere is a mixture of nitrogen and hydrogen, the reduction sintering temperature is 1390-1430℃, and the holding time is 1-3h.

[0086] It should be noted that nitrogen, as an inert gas, can expel oxygen during the sintering process, thereby preventing oxidation reactions in the material at high temperatures. This is crucial for maintaining the material's color and performance stability.

[0087] The reduction sintering was carried out under a nitrogen atmosphere at a temperature set between 1390℃ and 1430℃. This temperature range was chosen to ensure that the material could be further densified under a reducing atmosphere and to stabilize its color and properties. At the same time, the higher sintering temperature also helps to eliminate residual porosity and defects in the material, improving the overall quality of the product.

[0088] The holding time is also set to 1-3 hours. Similar to hot isostatic pressing, a reasonable holding time can ensure that the material undergoes sufficient physicochemical reactions under a reducing atmosphere, resulting in higher density and a more uniform structure.

[0089] In summary, by precisely controlling the process parameters of hot isostatic pressing (HIP) and reduction sintering, this embodiment can produce zirconia bicolor ceramic products with excellent performance and stable color. The optimization of these process parameters not only helps improve product quality and performance stability but also reduces production costs and increases production efficiency. Simultaneously, using nitrogen as a reducing atmosphere effectively prevents oxidation reactions of the material at high temperatures, ensuring that the product's color and performance remain unaffected.

[0090] S106. The bicolor ceramic blank is precision machined to obtain a zirconia ceramic part.

[0091] It should be noted that this step involves finishing the two-color ceramic blank after three sintering processes. Finishing includes processes such as surface grinding, CNC machining, polishing, and laser engraving to remove surface defects generated during sintering and to achieve the required surface finish and dimensional accuracy. The final product is a zirconia ceramic part with excellent performance and color consistency, such as a watch dial. Figure 5 As shown.

[0092] Although this application frequently uses terms such as single-stage pressing and sintering, the possibility of using other terms is not excluded. These terms are used merely for the convenience of describing and explaining the essence of the invention; interpreting them as any additional limitation would contradict the spirit of the invention.

[0093] This invention provides a method for preparing bicolor zirconia ceramics by co-firing. By adjusting the powder formula, red and black zirconia are pressed twice and subjected to various sintering methods, including cold isostatic pressing, air sintering, hot isostatic pressing, and reduction sintering. This ensures the performance of the red product while maintaining the color consistency and stability of the black product, thereby producing bicolor zirconia ceramic parts with diverse colors, high performance, and good color consistency.

[0094] Compared to traditional single-color zirconia ceramic parts, the bicolor zirconia ceramic parts of this invention exhibit a significant advantage in appearance color diversity. Simultaneously, these products possess excellent mechanical properties and superior color consistency. These characteristics make the bicolor zirconia ceramic products of this invention more competitive in the market, better serving customers with increasingly stringent requirements for product quality and appearance. By adjusting the granulation powder formula, the color bleeding range at the junction line was 0.24mm before improvement, with the junction line being faint and indistinct; after improvement, the color bleeding range at the junction line was 0.03mm, with the junction line clearly defined. The effect of improving the color bleeding at the junction line before and after adjusting the granulation powder is shown in the figure below. Figure 6 and 7 As shown.

[0095] Finally, it should be noted that although the above embodiments have been described in the text and drawings of this application, this should not limit the scope of patent protection of this application. Any technical solutions that are based on the essential concept of this application and utilize the content described in the text and drawings of this application, resulting in equivalent structural or procedural substitutions or modifications, as well as the direct or indirect application of the technical solutions of the above embodiments to other related technical fields, are all included within the scope of patent protection of this application.

Claims

1. A method for preparing zirconia bicolor ceramics by co-firing, characterized in that, The method includes: The red granulated powder and the black granulated powder are pressed into shape in a single press within a conforming steel mold. The red granulated powder comprises the following components by weight percentage: 92%-93% zirconium oxide, 3%-5% red colorant, and 2.5% stabilizer. The black granulated powder comprises the following components by weight percentage: 92%-93% zirconium oxide, 5% black colorant, and 2.5% stabilizer. The green blanks, after being pressed and shaped once, are placed into a molding die and pressed and shaped a second time. The green body after secondary pressing is then subjected to cold isostatic pressing. After cold isostatic pressing, the blank is debonded and pre-fired; then, it is sintered at high temperature in air atmosphere to obtain a first-fired blank. The first-fired blank is hot isostatically sintered in an inert atmosphere; subsequently, it is reduced sintered at high temperature in a reducing atmosphere to obtain a three-sintered bicolor ceramic blank. The bicolor ceramic blank is precision-machined to obtain a zirconia ceramic part; The red colorant is cerium oxide; The black colorant comprises iron, chromium, and nickel in a mass ratio of 2:2:

1.

2. The method for preparing zirconia bicolor ceramics by co-firing according to claim 1, characterized in that, The specifications for both the red granulated powder and the black granulated powder are as follows: D50 is 0.1-0.3μm, flowability is 45-55S, and loose pack density is 1.25-1.45g / cm³. 3 The powder shrinkage rate is 20%-21%.

3. The method for preparing zirconia bicolor ceramics by co-firing according to claim 1, characterized in that, The pressing pressure for the single pressing is 1T-3T, and the holding time is 2S.

4. The method for preparing zirconia bicolor ceramics by co-firing according to claim 1, characterized in that, The pressing pressure during the secondary pressing is 30-35T, and the density of the green embryo after secondary pressing is 3.0±0.2g / cm³. 3 .

5. The method for preparing zirconia bicolor ceramics by co-firing according to claim 1, characterized in that, Under air atmosphere, the sintering temperature is 1420-1490℃, the holding time is 1.5-2.5h, the heating rate is 3-4℃ / min, and the number of layers is 1-4.

6. The method for preparing zirconia bicolor ceramics by co-firing according to claim 1, characterized in that, The temperature for hot isostatic pressing sintering under an inert atmosphere is 1230-1350℃, and the holding time is 1-3h.

7. The method for preparing zirconia bicolor ceramics by co-firing according to claim 1, characterized in that, The reduction sintering temperature is 1390-1430℃, and the holding time is 1-3h.

8. The method for preparing zirconia bicolor ceramics by co-firing according to claim 1, characterized in that, The reducing atmosphere is a mixture of nitrogen and hydrogen.

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