Laminated sintered zirconia black ceramic circular knife and preparation method thereof

Abstract

The invention provides a laminated sintered zirconia black ceramic circular knife and a preparation method thereof, and belongs to the technical field of advanced ceramic materials and preparation. The method aims at solving the problems that an existing zirconia ceramic circular knife is limited in mechanical property, poor in reliability, high in preparation process cost and poor in environmental protection property. The preparation method provided by the invention comprises the following steps: preparing a ceramic green sheet from aqueous slurry through a tape casting process; superposing and stacking the ceramic green sheets in odd layers to form a laminated green body; and carrying out warm isostatic pressing treatment on the laminated green body. The invention further provides the circular knife prepared through the method, the circular knife comprises a plurality of ceramic layers formed through laminated sintering, the number of the ceramic layers is an odd number, and the relative density is not smaller than 99.6%. By adopting odd-number-layer stacking and combining warm isostatic pressing treatment, internal stress can be effectively balanced, microdefects can be eliminated, the compactness, strength and toughness of the tool are remarkably improved, and therefore the service life is prolonged.

Description

Technical Field

[0001] This application relates to the field of advanced ceramic materials and preparation technology, and in particular to a layered sintered zirconia black ceramic circular knife and its preparation method. Background Technology

[0002] In the lithium battery industry, the requirements for the cutting quality of battery electrodes (such as copper foil and aluminum foil) are becoming increasingly stringent. Traditional metal cutting tools are prone to wear and have a short lifespan during high-speed slitting, and the metal debris they produce can cause conductive particle contamination, thereby affecting the safety and consistency of the battery. Therefore, zirconia ceramic cutting tools, which have high hardness, high wear resistance, and chemical stability, have become an important alternative.

[0003] In existing technologies, methods for preparing zirconia ceramic cutting tools mainly involve monolithic molding and sintering, such as preparing individual ceramic green bodies through dry pressing, injection molding, or tape casting, followed by sintering. However, the microscopic defects inherent in such monolithically molded tools are prone to propagate during sintering or subsequent high-load use, leading to edge chipping or overall breakage, thus limiting the tool's mechanical properties and reliability. Furthermore, some existing processes utilize organic solvent systems, which not only increase manufacturing costs but also introduce environmental pollution and operational safety risks, failing to meet the requirements of modern industrial green manufacturing.

[0004] To improve the performance of cutting tools, some technologies have attempted to prepare multilayered ceramic materials. For example, this involves layering ceramic powders of different compositions and then hot-pressing them into a single unit. While this method envisions a multilayered structure, the powder layering and hot-pressing processes struggle to ensure absolute density uniformity between and within each layer. This easily leads to stress concentration points at interlayer interfaces or within the layers, causing defects such as warping and cracking during sintering. Consequently, the mechanical properties and batch consistency of the final product still require improvement. Therefore, current technology has not yet provided a method for preparing a zirconia ceramic circular knife that combines high mechanical properties, high reliability, low cost, and environmental safety. Summary of the Invention

[0005] The purpose of this application is to provide a layered sintered zirconia black ceramic circular knife and its preparation method, which aims to solve the technical problems of limited mechanical properties and poor reliability of zirconia ceramic circular knives in the prior art, as well as high cost, poor environmental performance, and poor product yield and consistency in the preparation process.

[0006] To achieve the above objective, this application provides a zirconia black ceramic circular knife with stacked sintering, characterized in that the circular knife comprises a plurality of ceramic layers formed by stacked sintering, and the number of ceramic layers is odd.

[0007] In a preferred embodiment, the number of ceramic layers is 3 or 5; the relative density of the circular blade is not less than 99.6%.

[0008] Furthermore, the bending strength of the circular cutter is not less than 1100 MPa.

[0009] This application also provides a method for preparing a stacked sintered zirconia black ceramic circular knife, characterized by the following steps: preparing ceramic green sheets using an aqueous slurry via a casting process; stacking the ceramic green sheets in multiple layers to form a stacked green body, wherein the number of layers of the ceramic green sheets is odd; subjecting the stacked green body to warm isostatic pressing treatment; sintering the green body after warm isostatic pressing treatment; and cutting and sharpening the sintered green body to obtain the circular knife.

[0010] Optionally, in the step of stacking ceramic green sheets in multiple layers, the number of ceramic green sheets is 3 or 5 layers.

[0011] Optionally, the aqueous slurry comprises Y2O3 stabilized zirconium oxide powder, black pigment, water-based dispersant, binder, glycerol, and silane defoamer.

[0012] Optionally, the conditions for the isostatic pressing treatment include: a temperature of 80-90℃, a pressure of 150-160MPa, and a holding time of 20-25 minutes.

[0013] Optionally, the sintering conditions include: a maximum temperature of 1440-1450°C, and a holding time of 3-4 hours at the maximum temperature.

[0014] As a specific implementation method, the conditions for the isostatic pressing treatment are a temperature of 80°C, a pressure of 160 MPa, and a holding time of 20 minutes; and the conditions for the sintering are a maximum temperature of 1450°C and a holding time of 3 hours.

[0015] Compared with existing technologies, the technical solution provided in this application has the following beneficial effects: By using cast ceramic green sheets to stack an odd number of layers, combined with warm isostatic pressing and subsequent sintering processes, this application can effectively balance the internal stress of the cutting tool and eliminate microscopic defects. This results in a ceramic circular cutting tool with higher density, significantly improved bending strength and fracture toughness, thus fundamentally solving the problems of easy breakage and chipping of existing cutting tools. The product has high reliability and a significantly extended service life. Furthermore, this application uses an aqueous system for cast sheet production, avoiding the use of organic solvents. This not only reduces manufacturing costs but also achieves safe and environmentally friendly green production, meeting modern industrial requirements. Simultaneously, the finished product is a stable black color, which is beneficial for positioning and detection by visual recognition systems on automated production lines, improving equipment compatibility and production efficiency. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application 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 this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic flowchart illustrating a method for preparing a layered sintered zirconia black ceramic circular knife according to an embodiment of this application.

[0018] The main reference numerals in the attached drawings are explained as follows: S10 - Preparation of water-based slurry; S20 - Preparation of ceramic green sheets by casting; S30 - Odd-numbered layer stacking; S40 - Warm isostatic pressing; S50 - High-temperature sintering; S60 - Post-treatment. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. It is to be understood that the specific embodiments described herein are merely illustrative of this application and not intended to limit it.

[0020] Example 1 This embodiment provides a layered sintered zirconia black ceramic circular knife and its preparation method. The preparation method disclosed in this application, through the synergistic effect of aqueous casting, odd-layer stacking, warm isostatic pressing, and high-temperature sintering, aims to prepare a high-performance ceramic circular knife with high density, high strength, and high toughness, to meet the stringent requirements for tool performance in precision cutting fields such as lithium battery electrode sheets.

[0021] Please see Figure 1 This is a schematic flowchart illustrating a method for preparing a layered sintered zirconia black ceramic circular knife according to an embodiment of this application. The method includes an aqueous slurry preparation step S10, a ceramic green sheet preparation step S20, an odd-layer stacking step S30, a warm isostatic pressing treatment step S40, a high-temperature sintering step S50, and a post-treatment step S60.

[0022] Step S10 is the aqueous slurry preparation step. This step aims to prepare a uniform, stable, and rheologically suitable aqueous ceramic slurry, laying the foundation for high-quality ceramic green sheets in subsequent tape casting. In one embodiment of this application, the slurry preparation adopts an environmentally friendly system using deionized water as a solvent, avoiding the environmental pollution and operational safety risks associated with traditional organic solvents. Specifically, the slurry components, by mass percentage, include: 3 mol% yttrium oxide partially stabilized zirconium oxide powder as the main ceramic raw material, which has an average particle size of approximately 0.2 micrometers, ensuring a fine grain structure after sintering, thereby improving the mechanical properties of the material; 0.1% black pigment, such as cobalt black or iron chromium black, which serves to give the final ceramic cutting tool a uniform black color, satisfying specific appearance requirements and facilitating accurate capture and positioning by a vision recognition system on an automated production line; and 25% WB4101 aqueous binder, a polymer emulsion whose main function is to provide sufficient flexibility and mechanical strength to the ceramic green sheet after drying. To facilitate subsequent cutting and lamination operations without cracking; to increase the flexibility of the green sheet and prevent cracking during drying, the slurry also includes 3% glycerol as a plasticizer; to eliminate air bubbles generated during slurry mixing and ball milling, the slurry also includes 1.5% silane defoamer. It should be noted that the presence of air bubbles will form pore defects in the final sintered body, seriously affecting the density and mechanical properties of the ceramic; in addition, the slurry also includes an appropriate amount of water-based dispersant, such as ammonium polyacrylate dispersant, which, through electrostatic repulsion or steric hindrance effect, uniformly disperses zirconia powder particles in the aqueous medium and prevents agglomeration, thereby ensuring the uniformity and stability of the slurry; finally, 20% deionized water is added as a solvent.

[0023] All the above components are placed in a ball mill jar lined with polyurethane or zirconia, and zirconia ball milling media are added. The mass ratio of ball milling media to materials is typically 2:1 to 3:1. High-speed ball milling is then performed at an appropriate rotation speed for 12 hours. This prolonged ball milling not only ensures uniform mixing of the various powder raw materials but also effectively breaks down any hard agglomerates that may exist in the powder raw materials. Furthermore, it allows organic additives such as dispersants and binders to be fully adsorbed onto the surface of the powder particles, forming a stable suspension system. After ball milling, the slurry is sieved to remove any impurities or large, incompletely dispersed particles, ultimately yielding a black ceramic slurry with a solid content of 60% and a viscosity of approximately 2000 centipoise at a specific shear rate. This viscosity range ensures good flowability during casting, allowing for smooth spreading without being too thin, which could lead to dripping or uneven thickness.

[0024] Step S20 is the process of preparing ceramic green sheets by tape casting. In this step, the black ceramic slurry prepared in the previous step is poured into the trough of the tape casting machine. A precisely controlled scraper device is used to cast the slurry onto a slowly moving polyester film substrate, transforming the liquid ceramic slurry into a solid sheet with a specific thickness and uniformity. In this embodiment, the gap between the scraper and the substrate is set to 0.25 mm, which determines the initial thickness of the wet film. The substrate travel speed is set to 1.0 m / min, and uniform movement ensures the continuity and uniformity of slurry spreading. The substrate coated with the wet film then enters a multi-temperature drying tunnel. The tunnel temperature is set to 60°C, and gentle heating gradually evaporates the moisture in the wet film. It should be noted that excessively fast drying may cause a skin to form on the surface of the green sheet, preventing internal moisture from escaping, which can lead to cracking or warping. Therefore, precise control of the drying temperature and time is necessary. After the moisture has completely evaporated, the binder and plasticizer, among other organic substances, form a network structure between the ceramic particles, making the dried ceramic green sheet a flexible sheet with a certain strength. Finally, the dried ceramic green sheet is completely peeled off from the polyester substrate to obtain a flexible ceramic green sheet with uniform thickness (approximately 0.20 mm), a smooth surface, and no cracks or bubbles.

[0025] Step S30 is the odd-layer stacking step, which is a key step in constructing the core multi-layer structure of this application. The flexible ceramic green sheet obtained in the previous step is precisely cut into uniform size and shape, such as round or square, using a cutting device. Then, five cut ceramic green sheets are taken and neatly stacked together to form a five-layer stacked structure. Choosing an odd number of layers (such as five layers in this embodiment) is an important technical feature of this application. This centrally symmetrical structural design, with a central layer and symmetrically distributed layers and thicknesses on both sides, can make the internal stress distribution more balanced and symmetrical during subsequent sintering shrinkage and final sharpening processes, thereby effectively suppressing warping deformation caused by uneven stress and significantly reducing the risk of edge breakage caused by stress concentration on the central surface during double-sided sharpening. After stacking, in order to initially bond the layers together, a pair of metal rollers are used to pre-press the stacked blank. By controlling the gap between the rolls and applying a thickness deformation of about 15%, residual air between layers can be expelled, allowing the green sheets to adhere tightly and preparing them for subsequent warm isostatic pressing.

[0026] Step S40 is the warm isostatic pressing (WIP) process, another core technical step of this application. Its purpose is to significantly improve the density and uniformity of the green body before sintering, eliminating internal microscopic defects. The pre-pressed laminated green bodies are placed in a polyurethane bag with good elasticity and sealing properties. The bag is then vacuum-sealed to remove residual air inside and between the layers of the green body, followed by heat sealing. The vacuum-sealed green body is then placed in the working chamber of a warm isostatic press. The warm isostatic press uses a liquid (such as water or oil) as the pressure transmission medium to apply uniformly high pressure to the workpiece placed within it. In this embodiment, the process parameters are set as follows: temperature heated to 80°C, pressure increased to 160 MPa, and maintained at this temperature and pressure for 20 minutes. Under the combined action of high temperature and high pressure, the ceramic particles in the green body undergo rearrangement and plastic flow to fill the pores between particles, while effective diffusion and bonding occur at the interfaces between layers. The 80°C temperature helps improve the plasticity of the organic binder, making the particles easier to move and compact. The isotropic pressure of 160 MPa ensures that the green body is uniformly compressed in all directions, effectively eliminating defects such as micropores and interlayer gaps that may be introduced by the casting and lamination processes. This significantly improves the relative density and microstructure uniformity of the green body. Understandably, this step lays a solid foundation for subsequent high-temperature sintering to obtain a near-fully dense sintered body and is crucial for achieving the final high-performance ceramic.

[0027] Step S50 is the high-temperature sintering step. This step aims to completely densify the compacted green body through atomic diffusion at high temperature, forming a ceramic crystal structure with excellent mechanical properties. The processed green body is removed from the isostatic pressing equipment, and its external vacuum packaging bag is removed. The green body is placed on an alumina pad and then sent into a high-temperature sintering furnace. In this embodiment, sintering is carried out in an air atmosphere. The sintering program is set as follows: starting from room temperature at a slow heating rate of 3°C / min, first rising to a lower temperature such as 600°C and holding for a period of time to completely burn off the binder, dispersant, and other organic matter in the green body, thus completing the debinding process. Too rapid debinding will cause the organic matter to vaporize instantly, generating huge pressure, thereby causing the green body to crack. After debinding is completed, the temperature continues to rise at a rate of 3°C / min to the final sintering temperature of 1450°C. The maximum temperature of 1450°C is held for 3 hours to ensure sufficient growth of ceramic grains and complete densification of the green body. After the heat treatment is completed, the heating power is turned off, and the sintered body is allowed to cool naturally to room temperature with the furnace to avoid cracking caused by thermal stress from rapid cooling. Through this step, a zirconia ceramic sintered body with a uniform black appearance and a dense structure is obtained.

[0028] Step S60 is the post-processing step, which aims to process the sintered block ceramic body into the final finished circular blade. First, the sintered body is precisely cut into a preset ring shape using laser cutting or an internal circular slicing machine. Next, the inner and outer surfaces of the ring are precision ground to achieve the required dimensional accuracy and surface finish. Then, the crucial sharpening process is performed, using a diamond grinding wheel to symmetrically sharpen both sides of the ring, forming a sharp double-sided cutting edge. The sharpening angle, blade width, and surface roughness are key parameters determining the cutting performance of the tool and require precise control. After processing, ceramic powder and debris generated during the process adhere to the tool surface and cutting edge. These residues can become a serious source of contamination when used for cutting battery electrodes. Therefore, the sharpened tool needs to be thoroughly cleaned. In this embodiment, the tool is placed in a deionized aqueous solution containing 0.5% (by weight) surfactant and ultrasonically cleaned for 10 minutes. The cavitation effect of ultrasound effectively removes fine particles adhering to the microstructure of the cutting edge. After cleaning, the blades are dried in an 80℃ oven to remove all moisture. Finally, the finished product undergoes rigorous quality inspection, including dimensions, geometric tolerances, cutting edge integrity, and microstructure. After passing the inspection, the blades are packaged with rust prevention measures to obtain the final zirconia black ceramic circular blade product.

[0029] The zirconia black ceramic circular cutter prepared by the above method has an integrated multi-layer structure formed by the sintering of five ceramic green sheets. Testing showed that its final relative density was greater than 99.6%, with almost no residual pores, directly attributed to the introduction of the warm isostatic pressing step S40. Its Vickers hardness was not less than 13 GPa, its flexural strength not less than 1100 MPa, and its fracture toughness was also significantly improved. When this circular cutter was installed on an industrial slitting machine for high-speed slitting tests on lithium battery carbon-coated aluminum foil with a width of 600 mm and a thickness of 9 micrometers, the cutter exhibited extremely high stability and durability at a linear velocity of 250 m / min. The cumulative stable cutting length of a single cutter exceeded 500,000 meters, more than five times the lifespan of a high-performance tungsten steel cutter of the same specification. Furthermore, the cut electrode edges were smooth and burr-free, with minimal debris, fully demonstrating the beneficial effects of the technical solution presented in this application.

[0030] Example 2 This embodiment aims to verify the universality of the odd-layer stack design proposed in this application, especially by using fewer layers (3 layers) to prepare ceramic circular cutters, to demonstrate the flexibility of this technical solution in meeting the needs of different product thickness specifications or cost-sensitive applications.

[0031] The preparation method in this embodiment is basically the same as that in Example 1, and also follows the same procedure. Figure 1The process flow shown includes the following steps: water-based slurry preparation step S10, ceramic green sheet preparation step S20, odd-layer stacking step S30, warm isostatic pressing step S40, high-temperature sintering step S50, and post-treatment step S60.

[0032] Specifically, the raw material formulation, mass percentage of each component, ball milling process, and performance parameters of the final slurry used in the water-based slurry preparation step S10 are completely consistent with those in Example 1. Correspondingly, the tape casting process parameters in the tape casting process S20 for preparing ceramic green sheets, the process conditions of the warm isostatic pressing process S40 (temperature 80°C, pressure 160 MPa, holding time 20 minutes), the sintering regime of the high-temperature sintering process S50 (heating rate, maximum temperature 1450°C, holding time 3 hours), and all processing and cleaning procedures in the post-treatment step S60 are also completely identical to those in Example 1.

[0033] The core difference between this embodiment and Embodiment 1 lies only in the odd-numbered layer stacking step S30. In this step, when stacking the cut ceramic green sheets, three layers are used instead of the five layers in Embodiment 1. This also constitutes an odd-numbered layered, centrally symmetrical structure, consisting of a central layer and two symmetrical layers on either side. After stacking, the layers are pre-pressed by metal rollers, followed by subsequent warm isostatic pressing and sintering.

[0034] Due to the reduced number of layers, the final ceramic circular cutter is thinner than that of Example 1. Despite the reduced thickness, its core performance indicators remain excellent. Testing showed that the three-layer ceramic circular cutter of this example exhibits key mechanical properties such as relative density, Vickers hardness, and bending strength that are essentially the same as the five-layer cutter of Example 1. For example, the relative density can also reach over 99.6%, and the bending strength remains at a very high level. This fully demonstrates that even with a smaller number of layers, the combination of an odd-numbered, centrally symmetrical structure and warm isostatic pressing can effectively balance internal stress and eliminate internal defects, thus ensuring the high performance of the final product. In practical application tests, the three-layer ceramic circular cutter was used in the same aluminum foil slitting process. Its cutting edge also exhibited excellent chipping resistance and high wear resistance during sharpening and high-speed cutting. Although its service life may be slightly lower than that of the five-layer product due to the reduced total thickness, it still far exceeds that of traditional single-piece integrally formed ceramic cutters and tungsten carbide cutters.

[0035] The results of this embodiment show that the odd-layer design proposed in this application (whether it is 3 layers, 5 layers or other odd-layer designs) is one of the core elements for realizing high-performance ceramic cutting tools. It has good universality and scalability, and can flexibly design and manufacture products of different specifications by adjusting the number of stacked layers according to different application scenarios and cost requirements.

[0036] Example 3 This embodiment aims to explore the process window of the preparation method proposed in this application. By adjusting some key process parameters, it verifies the robustness and applicability of the technical solution under different parameter combinations, thereby providing support for a wider range of production conditions.

[0037] The preparation method in this embodiment generally follows Figure 1 The process is shown, but different parameters are used in the aqueous slurry preparation step S10, the warm isostatic pressing treatment step S40, and the high-temperature sintering step S50 compared to Example 1.

[0038] In step S10 of the aqueous slurry preparation, the slurry formulation was slightly adjusted. Specifically, the solid content of the slurry was adjusted to 55%, the mass percentage of the binder was adjusted to 20%, and the content of glycerol was increased to 5%. This embodiment aims to verify whether subsequent processes can still guarantee product quality under such formulation fluctuations.

[0039] In step S20, which involves casting to prepare ceramic green sheets, the process parameters remain the same as in Example 1. In step S30, which involves stacking odd-numbered layers, this example still uses a 5-layer stacking method for direct comparison of process parameters with Example 1.

[0040] In the isostatic pressing step S40, the process parameters were adjusted as follows: the temperature was increased to 90°C, the pressure was reduced to 150 MPa, and the holding time was extended to 25 minutes. This set of parameters (90°C, 150 MPa, 25 minutes) and the parameters in Example 1 (80°C, 160 MPa, 20 minutes) both fall within a preferred range of process parameters (temperature 80-90°C, pressure 150-160 MPa, holding time 20-25 minutes). This example aims to verify the effectiveness of different parameter combinations within this range. It is understood that a higher temperature (90°C) can further improve the plasticity of the organic material, facilitating sufficient densification at a slightly lower pressure (150 MPa), while extending the holding time ensures sufficient compaction.

[0041] In the high-temperature sintering step S50, the sintering regime was also adjusted. Specifically, the temperature was increased to 1440°C at a slightly faster rate of 4°C / min, and held at the maximum temperature of 1440°C for 4 hours. This combination of "lower temperature + longer time" was designed to verify whether it could achieve a densification effect comparable to "higher temperature + shorter time". This set of sintering parameters (maximum temperature 1440°C, holding time 4 hours) also falls within a preferred process range (maximum temperature 1440-1450°C, holding time 3-4 hours).

[0042] The post-processing step S60 is exactly the same as in Example 1.

[0043] The ceramic circular slitter prepared in this embodiment was used to slit 6-micrometer-thick lithium battery copper foil, with the slitting line speed increased to 300 meters per minute, which placed higher demands on the slitter's performance. Test results showed that, despite adjustments to the slurry formulation and key process parameters, the final ceramic circular slitter still achieved extremely high densification (relative density not less than 99.5%) and excellent mechanical properties (flexural strength not less than 1050 MPa). Although the flexural strength value was slightly lower than the optimal value in Example 1, it was still far superior to the existing technology level, fully meeting the requirements for high-performance slitting applications.

[0044] The success of this embodiment demonstrates that the core technology combination disclosed in this application, namely water-based casting, odd-layer stacking, and warm isostatic pressing, has a wide process window. High-performance zirconia ceramic circular knives can be stably prepared even within a certain range of raw material formulation and process parameters (such as the temperature, pressure, and time of warm isostatic pressing, and the temperature and time of sintering). This has significant practical implications for large-scale industrial production, showcasing the good stability and industrial applicability of the method of this invention.

[0045] Example 4 This embodiment aims to verify the compatibility and adaptability of the preparation method proposed in this application to changes in raw materials. By using zirconium oxide powder with different particle sizes and adjusting the proportion of some additives to prepare ceramic circular knives, the wide applicability of the technical solution of this invention is demonstrated.

[0046] The preparation method in this embodiment also follows... Figure 1 The process flow shown includes the following core steps: casting step S20, odd-layer stacking step S30, warm isostatic pressing step S40, high-temperature sintering step S50, and post-treatment step S60. The process parameters are identical to those in Example 1. The main change in this example lies in the raw material composition of the water-based slurry preparation step S10.

[0047] In step S10 of preparing the aqueous slurry, the raw material formulation was adjusted as follows: the main ceramic raw material was 3 mol% yttrium oxide stabilized zirconium oxide powder with an average particle size of 0.4 micrometers, which is larger than the 0.2 micrometers in Example 1. The amount of black pigment added was increased to 0.15% to obtain a deeper black appearance. The content of the aqueous binder was increased to 30% to compensate for the possible decrease in green sheet strength caused by the larger particle size powder. The content of the silane defoamer was adjusted to 1%. The amounts of other components, such as glycerol, water-based dispersant, and water, remained the same as in Example 1. These adjusted components were ball-milled in the same way as in Example 1 to prepare a uniform ceramic slurry.

[0048] It should be noted that although the starting raw material powder has a relatively large particle size, the core process steps of this application, especially the warm isostatic pressing step S40 and the optimized sintering step S50, can effectively promote the densification of the green body and control abnormal grain growth. The warm isostatic pressing process, through strong isotropic pressure, forces the particles to rearrange and fill, compensating for the inherently low packing density of the larger particle size powder. In the subsequent sintering process, because the green body already has a very high initial density, the sintering shrinkage is smaller and more uniform, thereby suppressing poor densification and abnormal grain growth that may be caused by particle size inhomogeneity.

[0049] The ceramic circular cutter prepared in this embodiment was subjected to performance testing and application testing. The results showed that the grain size of the final product was slightly larger than that of Example 1, but due to the strengthening effect of the laminated structure and the warm isostatic pressing process, its final relative density and mechanical properties remained at a very high level, fully meeting the requirements for high-reliability slitting applications. The finished product's color was deeper due to the increased pigment content, exhibiting a very uniform dark black. It was used for slitting tests on lithium battery electrodes coated with positive electrode active materials; this application scenario places more stringent requirements on the cutter's wear resistance and chipping resistance. Test results showed that the cutter prepared in this embodiment also exhibited long lifespan and excellent cutting quality.

[0050] The results of this embodiment strongly demonstrate that the preparation method disclosed in this application has good adaptability and robustness to the selection of raw materials. Even when parameters such as the particle size of the raw material powder change, the unique "odd-number layer stacking + warm isostatic pressing" core technology of this application can still produce high-performance ceramic cutting tools, which further broadens the application scope and industrial applicability of the technology of this invention.

[0051] The above description is merely a preferred embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A layered sintered zirconia black ceramic circular knife, characterized in that, The circular knife comprises multiple ceramic layers formed by stacking and sintering, and the number of ceramic layers is odd.

2. The circular knife according to claim 1, characterized in that, The ceramic layer has 3 or 5 layers; the relative density of the circular blade is not less than 99.6%.

3. The circular knife according to any one of claims 1 or 2, characterized in that, The bending strength of the circular cutter is not less than 1100 MPa.

4. A method for preparing a layered sintered zirconia black ceramic circular knife, characterized in that, Includes the following steps: Ceramic green sheets are prepared by casting process using water-based slurry; the ceramic green sheets are stacked in multiple layers to form a laminated green body, wherein the number of layers of ceramic green sheets is odd; the laminated green body is subjected to warm isostatic pressing; the green body after warm isostatic pressing is sintered; and the sintered green body is cut and sharpened to obtain the circular knife.

5. The preparation method according to claim 4, characterized in that, In the step of stacking ceramic green sheets in multiple layers, the number of ceramic green sheets is 3 or 5 layers.

6. The preparation method according to claim 4 or 5, characterized in that, The aqueous slurry contains Y2O3 stabilized zirconium oxide powder, black pigment, water-based dispersant, binder, glycerol, and silane defoamer.

7. The preparation method according to any one of claims 4 to 6, characterized in that, The conditions for the isostatic pressing treatment include: a temperature of 80-90℃, a pressure of 150-160MPa, and a holding time of 20-25 minutes.

8. The preparation method according to claim 7, characterized in that, The sintering conditions include: a maximum temperature of 1440-1450℃, and a holding time of 3-4 hours at the maximum temperature.

9. The preparation method according to claim 8, characterized in that, The conditions for the isostatic pressing treatment are a temperature of 80°C, a pressure of 160 MPa, and a holding time of 20 minutes; and the conditions for the sintering are a maximum temperature of 1450°C and a holding time of 3 hours.

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