Aluminum oxide ceramic high-temperature fast firing method

Abstract

The invention relates to the technical field of preparation of advanced ceramic materials, and provides a high-temperature fast firing method for alumina ceramics in order to solve the problems that a traditional gas furnace is too long in sintering period and cannot meet emergency production requirements and the quality problem occurs when a traditional process is directly transplanted to an electric furnace. The temperature transition from room temperature to the target sintering temperature is ensured to be completed within a short time, meanwhile, the densification, grain growth and other processes of the ceramic material are ensured to be stably carried out through accurate temperature control in each stage, short-period high-quality sintering from a green body to a finished product is achieved, high-quality product preparation can be completed within 72-96 hours, and the production cost is reduced. The method is especially suitable for small-batch, multi-variety and emergency order production modes; parameters are flexibly adjusted and can be quickly optimized according to product requirements; and the adaptability to electric furnace models and specifications is high.

Description

Technical Field

[0001] This invention relates to the field of advanced ceramic material preparation technology, specifically to a method for rapid sintering of alumina ceramics using a high-temperature electric furnace. Background Technology

[0002] Alumina ceramics, as an important engineering ceramic material, are widely used in electronics, machinery, and chemical industries. While traditional gas furnace sintering processes can produce products with stable performance, their firing cycle typically lasts 10-14 days, including multiple stages such as slow heating, prolonged holding, and segmented cooling. This long-cycle sintering method has the following significant drawbacks: 1. Low production efficiency: It cannot meet the demands of modern manufacturing, such as urgent orders, rapid sample production, and small-batch, multi-variety production. 2. High energy consumption: The long holding stage consumes a large amount of energy, increasing production costs. 3. Slow response time: The excessively long order-to-product delivery cycle affects customer satisfaction and market competitiveness. 4. Poor process flexibility: Traditional process parameters are fixed and difficult to adjust quickly according to product specifications. In the prior art, for example, Chinese patent document CN 107032765B discloses a method for rapid high-temperature solid-state sintering of alumina ceramics, achieving rapid high-temperature solid-state sintering of alumina ceramics under pressureless conditions. This patent describes a heating rate of 500°C / s to 600°C / s, a rapid heating time of 3 to 4 seconds, and a brief holding time of 1 to 2 minutes. However, rapid heating leads to cracking of the green body; insufficient holding time results in incomplete densification, among other problems.

[0003] With the development of high-temperature electric furnace technology, it has the following advantages: (1) fast heating rate, up to 10-20℃ / min; (2) precise temperature control, which can achieve precise execution of complex temperature curves; (3) the furnace atmosphere is a natural air environment, without the need for an additional atmosphere control system; (4) the heating element (silicon molybdenum rod) can work stably for a long time in an oxidizing atmosphere. However, when the traditional long-cycle sintering process is directly applied to the electric furnace for rapid firing, the following problems will occur: (1) rapid heating leads to cracking of the billet; (2) insufficient holding time leads to incomplete densification; (3) excessively rapid cooling generates thermal stress cracks; (4) uneven microstructure and unstable performance.

[0004] Therefore, there is an urgent need to develop a rapid sintering method for alumina ceramics specifically designed for the characteristics of high-temperature electric furnaces, which can shorten the firing cycle from the traditional two weeks to 3-4 days while ensuring product quality, thus meeting the demand for rapid response in modern manufacturing. Summary of the Invention

[0005] To address the problems of excessively long sintering cycles in traditional gas furnaces, which cannot meet urgent production needs, and the quality issues that arise when directly transferring traditional processes to electric furnaces, this invention provides a high-temperature rapid sintering method for alumina ceramics, which can complete the preparation of high-quality products within 72-96 hours.

[0006] The technical solution of this invention is as follows: a high-temperature rapid sintering method for alumina ceramics, based on the alumina ceramic electric furnace sintering method, employs a rapid temperature regime in the air environment of a high-temperature electric furnace: using a heating rate of 1-3℃ / min to ensure the temperature transition from room temperature to the target sintering temperature is completed in a short time. Simultaneously, precise temperature control at each stage ensures the stable progress of processes such as densification and grain growth of the ceramic material, achieving short-cycle, high-quality sintering from green body to finished product. The method specifically includes the following steps: Step 1: Raw material and green body preparation Organic binders and sintering aids are added to alumina powder, and after spray granulation, green blanks are prepared by dry pressing and isostatic pressing, with the green blank density reaching 45-65% of the theoretical density.

[0007] Preferably, the alumina powder used has a purity of ≥95% and an average particle size controlled between 0.5-3.0μm.

[0008] Preferably, the organic binder is selected from polyvinyl alcohol (PVA) or polyacrylic acid (PAA), and the amount used is 0.5-2% of the mass of alumina powder, which is used to improve the formability of the green body.

[0009] Preferably, the sintering aid is selected from magnesium oxide (MgO) and is used at 0.5-1% of the mass of alumina powder. It can promote the sintering of alumina and help improve its mechanical strength.

[0010] Step 2: Integrated Dewaxing-Sintering Rapid Process Place the green billet into a high-temperature electric furnace and execute the following continuous temperature program. (1) First stage: This is the de-adhesion stage. First, the temperature is raised from room temperature to 120℃ at a rate of 1-3℃ / min to allow the low-temperature organic matter to slowly volatilize. Then, the temperature is raised from 120℃ to 350℃ at a rate of 1-3℃ / min to allow the low-temperature organic matter to slowly volatilize completely. Then, the temperature is raised from 350℃ to 800℃ at a rate of 1-3℃ / min. Finally, the temperature is maintained for 300-420 minutes to completely remove the residual organic matter. (2) Second stage: Medium-speed heating stage (800℃→1100℃): The temperature is raised to 1100℃ at a uniform rate of 1-3℃ / min. This stage promotes the initial sintering of particles and the formation of strength. The holding time is 2-4 hours.

[0011] (3) Third stage: Preliminary densification stage (1100℃→1450℃): The temperature is increased from 1100℃ to 1450℃ at a rate of 1-3℃ / min, and the holding time is 2-4 hours.

[0012] (4) Fourth stage: Grain growth stage (1450℃-1640℃), the temperature is increased from 1450℃ to 1640℃ at a rate of 1-3℃ / min, and the holding time is 0.5-2 hours; (5) Fifth stage: Controllable rapid cooling stage. First, the temperature is reduced from the sintering temperature to 1550℃ at a rate of 3-6℃ / min. This is the initial cooling. At this time, the ceramic is annealed to eliminate defects. The holding time is 8-12 hours. Then, the temperature is reduced from 1550℃ to room temperature at a rate of 1-3℃ / min. The total cooling time is 33-43 hours to prevent excessive thermal stress.

[0013] The entire process takes place in the natural air environment of the electric furnace.

[0014] Step 3: Post-processing After sintering, finishing processes such as grinding and polishing can be performed as needed.

[0015] The above-mentioned rapid sintering method for alumina ceramics utilizes an electric furnace and can complete the preparation of high-quality products within 96 hours.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) Extremely short firing cycle: The traditional 2-week firing cycle is shortened to less than 96 hours. (2) Excellent overall performance: Through an optimized rapid temperature profile, quality is guaranteed while reducing the time required. Density can reach 96-99% of theoretical density; three-point bending strength: ≥350MPa (99.7% alumina); Vickers hardness: ≥15GPa; uniform microstructure, average grain size: 2-8μm.

[0017] (3) Significant energy-saving effect: Total energy consumption is reduced by 50-70%; no atmosphere protection system is required, and the equipment is simple; production efficiency is greatly improved, and unit energy consumption is reduced.

[0018] (4) Good process adaptability: It is particularly suitable for production modes of small batches, multiple varieties, and urgent orders; the parameters can be adjusted flexibly and can be quickly optimized according to product requirements; it is highly adaptable to electric furnace models and specifications. Attached Figure Description

[0019] Figure 1 The image shows a scanning electron microscope (SEM) image of the microstructure of the alumina ceramic prepared in Example 1. Detailed Implementation

[0020] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. However, it should be understood that the examples are intended to help illustrate the method and beneficial effects of the present invention, and are not intended to limit the scope of protection of the present invention. The raw materials used in the embodiments can all be commercially available or prepared by conventional methods.

[0021] In the examples, alumina powder with a purity of 99.7% was used, and the particle size was controlled between 0.5 and 3.0 μm.

[0022] Example 1: A method for high-temperature rapid firing of alumina ceramics Step 1: Raw material and green body preparation 200g of alumina powder with a particle size controlled at 2μm, 2g of organic binder polyvinyl alcohol (PVA), and 2g of sintering aid magnesium oxide (MgO).

[0023] After uniformly mixing alumina powder with organic binder and sintering aid, the mixture is pressed into a green body using a dry pressing method. The specific steps are as follows: the alumina powder mixture is added to a mold and pressed using a pressure of approximately 40 MPa to ensure the uniformity and density of the green body.

[0024] Based on the dry-pressed billet, it is further pressed using isostatic pressing to ensure the uniformity and density of the billet. The billet is processed in an isostatic press at a pressure of 80 MPa for 8 minutes. The density of the pressed billet should reach 55% of the theoretical density.

[0025] The prepared green body is dried at room temperature to remove excess moisture and ensure its stability.

[0026] Step 2: Integrated Dewaxing-Sintering Rapid Process (1) Debonding stage: Place the billet in a high-temperature electric furnace and execute the following temperature program: Heating rate: 1℃ / min, from room temperature to 120℃, then from 120℃ to 350℃, and finally to 800℃, then hold for 360 minutes to ensure complete volatilization of organic matter.

[0027] (2) Heating stage: First, the temperature is increased to 1100℃ at a rate of 2℃ / min and held for 3 hours to ensure initial sintering and the formation of intergranular strength. Then, the temperature is increased to 1450℃ at a rate of 2℃ / min and held for 3 hours. Next, the temperature is increased to 1640℃ at a rate of 2℃ / min and held for 1 hour.

[0028] (3) Cooling stage: First, the sintering temperature is lowered to 1550℃ at a cooling rate of 5℃ / min for rapid cooling, and the holding time is 10 hours. Then, the temperature is lowered from 1550℃ to room temperature at a cooling rate of 2℃ / min and held for 16 hours.

[0029] Step 3: Post-processing: Grinding and polishing: After sintering, grinding, polishing and other finishing processes are performed as needed to achieve the dimensional requirements and surface quality of the final product.

[0030] Scanning electron microscope (SEM) images of the microstructure of the prepared alumina ceramics are shown below. Figure 1 As shown, the sintering time is approximately 72 hours.

[0031] Example 2: A method for high-temperature rapid firing of alumina ceramics Step 1: Raw material and green body preparation 200g of alumina powder with a particle size controlled at 2μm, 2g of organic binder polyvinyl alcohol (PVA), and 2g of sintering aid magnesium oxide (MgO).

[0032] After uniformly mixing alumina powder with organic binder and sintering aid, the mixture is pressed into a green body using a dry pressing method. The specific steps are as follows: the alumina powder mixture is added to a mold, and pressure of approximately 30 MPa is applied to press the green body to ensure its uniformity and density.

[0033] Based on the dry-pressed billet, it is further pressed using isostatic pressing to ensure the uniformity and density of the billet. The billet is processed in an isostatic press at a pressure of 50 MPa for 5 minutes. The density of the pressed billet should reach 45% of the theoretical density.

[0034] The prepared green body is dried at room temperature to remove excess moisture and ensure its stability.

[0035] Step 2: Integrated Dewaxing-Sintering Rapid Process (1) Debonding stage: Place the billet in a high-temperature electric furnace and execute the following temperature program: Heating rate: 1℃ / min, from room temperature to 120℃, then from 120℃ to 350℃, and finally to 800℃, then hold for 360 minutes to ensure complete volatilization of organic matter.

[0036] (2) Heating stage: First, the temperature is increased to 1100℃ at a rate of 2℃ / min and held for 3 hours to ensure initial sintering and the formation of intergranular strength. Then, the temperature is increased to 1450℃ at a rate of 2℃ / min and held for 3 hours. Next, the temperature is increased to 1640℃ at a rate of 2℃ / min and held for 1 hour.

[0037] (3) Cooling stage: First, the sintering temperature is reduced to 1550℃ at a cooling rate of 5℃ / min for rapid cooling; then, the temperature is reduced from 1550℃ to room temperature at a cooling rate of 2℃ / min.

[0038] Step 3: Post-processing: Grinding and polishing: After sintering, grinding, polishing and other finishing processes are performed as needed to achieve the dimensional requirements and surface quality of the final product.

[0039] Example 3: A method for high-temperature rapid firing of alumina ceramics: Step 1: Raw material and green body preparation 200g of alumina powder with a particle size controlled at 2μm, 2g of organic binder polyvinyl alcohol (PVA), and 2g of sintering aid magnesium oxide (MgO).

[0040] After uniformly mixing alumina powder with organic binder and sintering aid, the mixture is pressed into a green body using a dry pressing method. The specific steps are as follows: the alumina powder mixture is added to a mold, and pressing is performed using a pressure of approximately 50 MPa to ensure the uniformity and density of the green body.

[0041] Based on the dry-pressed billet, it is further pressed using isostatic pressing to ensure the uniformity and density of the billet. The billet is processed in an isostatic press at a pressure of 100 MPa for 10 minutes. The density of the pressed billet should reach 65% of the theoretical density.

[0042] The prepared green body is dried at room temperature to remove excess moisture and ensure its stability.

[0043] Step 2: Integrated Dewaxing-Sintering Rapid Process (1) Debonding stage: Place the billet in a high-temperature electric furnace and execute the following temperature program: Heating rate: 1℃ / min, from room temperature to 120℃, then from 120℃ to 350℃, and finally to 800℃, then hold for 360 minutes to ensure complete volatilization of organic matter.

[0044] (2) Heating stage: First, the temperature is increased to 1100℃ at a rate of 2℃ / min and held for 3 hours to ensure initial sintering and the formation of intergranular strength. Then, the temperature is increased to 1450℃ at a rate of 2℃ / min and held for 3 hours. Next, the temperature is increased to 1640℃ at a rate of 2℃ / min and held for 1 hour.

[0045] (3) Cooling stage: First, the sintering temperature is reduced to 1550℃ at a cooling rate of 5℃ / min for rapid cooling; then, the temperature is reduced from 1550℃ to room temperature at a cooling rate of 2℃ / min.

[0046] Step 3: Post-processing: Grinding and polishing: After sintering, grinding, polishing and other finishing processes are performed as needed to achieve the dimensional requirements and surface quality of the final product.

[0047] Example 4: A method for high-temperature rapid firing of alumina ceramics Step 1: Raw material and green body preparation 200g of alumina powder with a particle size controlled at 2μm, 2g of organic binder polyacrylic acid (PAA), and 2g of sintering aid magnesium oxide (MgO).

[0048] After uniformly mixing alumina powder with organic binder and sintering aid, the mixture is pressed into a green body using a dry pressing method. The specific steps are as follows: the alumina powder mixture is added to a mold and pressed using a pressure of approximately 40 MPa to ensure the uniformity and density of the green body.

[0049] Based on the dry-pressed billet, it is further pressed using isostatic pressing to ensure the uniformity and density of the billet. The billet is processed in an isostatic press at a pressure of 80 MPa for 8 minutes. The density of the pressed billet should reach 55% of the theoretical density.

[0050] The prepared green body is dried at room temperature to remove excess moisture and ensure its stability.

[0051] Step 2: Integrated Dewaxing-Sintering Rapid Process (1) Debonding stage: Place the billet in a high-temperature electric furnace and execute the following temperature program: Heating rate: 2℃ / min, from room temperature to 120℃, then from 120℃ to 350℃, and finally to 800℃, then hold for 360 minutes to ensure complete volatilization of organic matter.

[0052] (2) Heating stage: First, the temperature is increased to 1100℃ at a rate of 2℃ / min and held for 3 hours to ensure initial sintering and the formation of intergranular strength. Then, the temperature is increased to 1450℃ at a rate of 2℃ / min and held for 3 hours. Next, the temperature is increased to 1640℃ at a rate of 2℃ / min and held for 1 hour.

[0053] (3) Cooling stage: First, the sintering temperature is lowered to 1550℃ at a cooling rate of 5℃ / min for rapid cooling, and then held at that temperature for about 10 hours; then the temperature is lowered from 1550℃ to room temperature at a cooling rate of 2℃ / min for 20 hours.

[0054] Step 3: Post-processing: Grinding and polishing: After sintering, grinding, polishing and other finishing processes are performed as needed to achieve the dimensional requirements and surface quality of the final product.

[0055] Comparative Example 1: A method for high-temperature sintering of alumina ceramics The difference from Example 1 is that the heating rate in step (2) is usually 4°C / min to accelerate the sintering process.

[0056] Step 1: Raw material and green body preparation 200g of alumina powder with a particle size controlled at 2μm, 2g of organic binder polyvinyl alcohol (PVA), and 2g of sintering aid magnesium oxide (MgO).

[0057] After uniformly mixing alumina powder with organic binder and sintering aid, the mixture is pressed into a green body using a dry pressing method. The specific steps are as follows: the alumina powder mixture is added to a mold and pressed using a pressure of approximately 40 MPa to ensure the uniformity and density of the green body.

[0058] Based on the dry-pressed billet, it is further pressed using isostatic pressing to ensure the uniformity and density of the billet. The billet is processed in an isostatic press at a pressure of 80 MPa for 8 minutes. The density of the pressed billet should reach 55% of the theoretical density.

[0059] The prepared green body is dried at room temperature to remove excess moisture and ensure its stability.

[0060] Step 2: Integrated Dewaxing-Sintering Rapid Process (1) Debonding stage: Place the billet in a high-temperature electric furnace and execute the following temperature program: Heating rate: 1℃ / min, from room temperature to 120℃, then from 120℃ to 350℃, and finally to 800℃, then hold for 360 minutes to ensure complete volatilization of organic matter.

[0061] (2) Heating stage: First, the temperature is increased to 1100℃ at a rate of 4℃ / min and held for 3 hours to ensure initial sintering and the formation of intergranular strength. Then, the temperature is increased to 1450℃ at a rate of 4℃ / min and held for 3 hours. Next, the temperature is increased to 1640℃ at a rate of 4℃ / min and held for 1 hour.

[0062] (3) Cooling stage: First, the sintering temperature is reduced to 1550℃ at a cooling rate of 5℃ / min for rapid cooling; then, the temperature is reduced from 1550℃ to room temperature at a cooling rate of 2℃ / min.

[0063] Step 3: Post-processing: Grinding and polishing: After sintering, grinding, polishing and other finishing processes are performed as needed to achieve the dimensional requirements and surface quality of the final product.

[0064] Comparative Example 2: A method for high-temperature sintering of alumina ceramics: The difference from Example 1 is that the heating rate in step (2) is usually 0.5℃ / min to ensure that the microstructure of the ceramic is more uniform.

[0065] Step 1: Raw material and green body preparation 200g of alumina powder with a particle size controlled at 2μm, 2g of organic binder polyvinyl alcohol (PVA), and 2g of sintering aid magnesium oxide (MgO).

[0066] After uniformly mixing alumina powder with organic binder and sintering aid, the mixture is pressed into a green body using a dry pressing method. The specific steps are as follows: the alumina powder mixture is added to a mold and pressed using a pressure of approximately 40 MPa to ensure the uniformity and density of the green body.

[0067] Based on the dry-pressed billet, it is further pressed using isostatic pressing to ensure the uniformity and density of the billet. The billet is processed in an isostatic press at a pressure of 80 MPa for 8 minutes. The density of the pressed billet should reach 55% of the theoretical density.

[0068] The prepared green body is dried at room temperature to remove excess moisture and ensure its stability.

[0069] Step 2: Integrated Dewaxing-Sintering Rapid Process (1) Debonding stage: Place the billet in a high-temperature electric furnace and execute the following temperature program: Heating rate: 1℃ / min, from room temperature to 120℃, then from 120℃ to 350℃, and finally to 800℃, then hold for 360 minutes to ensure complete volatilization of organic matter.

[0070] (2) Heating stage: First, the temperature is increased to 1100℃ at a rate of 0.5℃ / min and held for 3 hours to ensure initial sintering and the formation of intergranular strength. Then, the temperature is increased to 1450℃ at a rate of 0.5℃ / min and held for 3 hours. Next, the temperature is increased to 1640℃ at a rate of 0.5℃ / min and held for 1 hour.

[0071] (3) Cooling stage: First, the sintering temperature is reduced to 1550℃ at a cooling rate of 5℃ / min for rapid cooling; then, the temperature is reduced from 1550℃ to room temperature at a cooling rate of 2℃ / min.

[0072] Step 3: Post-processing: Grinding and polishing: After sintering, grinding, polishing and other finishing processes are performed as needed to achieve the dimensional requirements and surface quality of the final product.

[0073] Comparative Example 3: A method for high-temperature sintering of alumina ceramics The difference from Example 1 is that in step 2 (3) slow cooling rate: initial cooling stage: from sintering temperature to 1550℃, use a rate of 1℃ / min, and then from 1550℃ to room temperature, use a rate of 0.5℃ / min.

[0074] Step 1: Raw material and green body preparation 200g of alumina powder with a particle size controlled at 2μm, 2g of organic binder polyvinyl alcohol (PVA), and 2g of sintering aid magnesium oxide (MgO).

[0075] After uniformly mixing alumina powder with organic binder and sintering aid, the mixture is pressed into a green body using a dry pressing method. The specific steps are as follows: the alumina powder mixture is added to a mold and pressed using a pressure of approximately 40 MPa to ensure the uniformity and density of the green body.

[0076] Based on the dry-pressed billet, it is further pressed using isostatic pressing to ensure the uniformity and density of the billet. The billet is processed in an isostatic press at a pressure of 80 MPa for 8 minutes. The density of the pressed billet should reach 55% of the theoretical density.

[0077] The prepared green body is dried at room temperature to remove excess moisture and ensure its stability.

[0078] Step 2: Integrated Dewaxing-Sintering Rapid Process (1) Debonding stage: Place the billet in a high-temperature electric furnace and execute the following temperature program: Heating rate: 1℃ / min, from room temperature to 120℃, then from 120℃ to 350℃, and finally to 800℃, then hold for 360 minutes to ensure complete volatilization of organic matter.

[0079] (2) Heating stage: First, the temperature is increased to 1100℃ at a rate of 2℃ / min and held for 3 hours to ensure initial sintering and the formation of intergranular strength. Then, the temperature is increased to 1450℃ at a rate of 2℃ / min and held for 3 hours. Next, the temperature is increased to 1640℃ at a rate of 2℃ / min and held for 1 hour.

[0080] (3) Cooling stage: First, the sintering temperature is reduced to 1550℃ at a cooling rate of 1℃ / min for rapid cooling; then, the temperature is reduced from 1550℃ to room temperature at a cooling rate of 0.5℃ / min.

[0081] Step 3: Post-processing: Grinding and polishing: After sintering, grinding, polishing and other finishing processes are performed as needed to achieve the dimensional requirements and surface quality of the final product.

[0082] Comparative Example 4: A method for high-temperature sintering of alumina ceramics The difference from Example 1 is that in step 2 (3) rapid cooling rate: initial cooling stage: from sintering temperature to 1550℃, using a rate of 6℃ / min; rapid cooling stage: from 1550℃ to room temperature, using a rate of 4℃ / min.

[0083] Step 1: Raw material and green body preparation 200g of alumina powder with a particle size controlled at 2μm, 2g of organic binder polyvinyl alcohol (PVA), and 2g of sintering aid magnesium oxide (MgO).

[0084] After uniformly mixing alumina powder with organic binder and sintering aid, the mixture is pressed into a green body using a dry pressing method. The specific steps are as follows: the alumina powder mixture is added to a mold and pressed using a pressure of approximately 40 MPa to ensure the uniformity and density of the green body.

[0085] Based on the dry-pressed billet, it is further pressed using isostatic pressing to ensure the uniformity and density of the billet. The billet is processed in an isostatic press at a pressure of 80 MPa for 8 minutes. The density of the pressed billet should reach 55% of the theoretical density.

[0086] The prepared green body is dried at room temperature to remove excess moisture and ensure its stability.

[0087] Step 2: Integrated Dewaxing-Sintering Rapid Process (1) Debonding stage: Place the billet in a high-temperature electric furnace and execute the following temperature program: Heating rate: 1℃ / min, from room temperature to 120℃, then from 120℃ to 350℃, and finally to 800℃, then hold for 360 minutes to ensure complete volatilization of organic matter.

[0088] (2) Heating stage: First, the temperature is increased to 1100℃ at a rate of 2℃ / min and held for 3 hours to ensure initial sintering and the formation of intergranular strength. Then, the temperature is increased to 1450℃ at a rate of 2℃ / min and held for 3 hours. Next, the temperature is increased to 1640℃ at a rate of 2℃ / min and held for 1 hour.

[0089] (3) Cooling stage: First, the sintering temperature is reduced to 1550℃ at a cooling rate of 6℃ / min for rapid cooling; then, the temperature is reduced from 1550℃ to room temperature at a cooling rate of 4℃ / min.

[0090] Step 3: Post-processing: Grinding and polishing: After sintering, grinding, polishing and other finishing processes are performed as needed to achieve the dimensional requirements and surface quality of the final product.

[0091] Test Example 1 The effects of different sintering temperature curves are shown in Table 1: Table 1: Results analysis: As shown in Table 1, a faster heating rate results in a slightly shorter sintering cycle, but may lead to a slight decrease in microstructure and mechanical properties. A slower heating rate results in better density and mechanical properties, but a longer sintering cycle, making it unsuitable for emergency production.

[0092] Test Example 2 The effect of different green body densities on sintering performance is shown in Table 2: Table 2: Results analysis: As shown in Table 2, the higher the density of the green body, the better the sintering effect. Higher density results in more uniform grains and optimal mechanical properties and hardness.

[0093] Test Example 3 The effect of cooling rate on performance is shown in Table 3: Table 3: Results analysis: As shown in Table 3, slow cooling rate: effectively eliminates thermal stress, results in smaller grains, and better mechanical properties. Okay, but it takes a long time; rapid cooling rate: although it saves time, it will lead to increased thermal stress, which may cause cracks and affect the overall performance of the ceramic.

[0094] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made using the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for high-temperature rapid firing of alumina ceramics, characterized in that, The high-temperature rapid heating method includes the following steps: Step 1: Add organic binder and sintering aid to alumina powder, and after spray granulation, prepare green blanks by dry pressing and isostatic pressing. The density of the green blanks reaches 45-65% of the theoretical density. Step 2: Place the green billet into the high-temperature electric furnace and execute the following continuous temperature program; Step 3: After sintering, grinding and polishing can be performed as needed.

2. The high-temperature rapid firing method for alumina ceramics according to claim 1, characterized in that, The alumina powder used has a purity of ≥95% and an average particle size controlled between 0.5-3.0μm.

3. The high-temperature rapid firing method for alumina ceramics according to claim 1, characterized in that, The organic binder is selected from polyvinyl alcohol or polyacrylic acid, and the amount used is 0.5-2% of the mass of alumina powder.

4. The high-temperature rapid firing method for alumina ceramics according to claim 1, characterized in that, The sintering aid is selected from magnesium oxide and is used at a rate of 0.5-1% of the mass of alumina powder.

5. The high-temperature rapid firing method for alumina ceramics according to claim 1, characterized in that, Step two includes the debinding stage, the medium-speed heating stage, the preliminary densification stage, the grain growth stage, and the rapid cooling stage.

6. A method for high-temperature rapid firing of alumina ceramics according to claim 1 or 5, characterized in that, The debonding stage is as follows: first, the temperature is increased from room temperature to 120℃ at a rate of 1-3℃ / min; then, the temperature is increased from 120℃ to 350℃ at a rate of 1-3℃ / min; then, the temperature is increased from 350℃ to 800℃ at a rate of 1-3℃ / min; and finally, the temperature is maintained for 300-420 minutes.

7. A method for high-temperature rapid firing of alumina ceramics according to claim 1 or 5, characterized in that, Medium-speed heating stage: Heat to 1100℃ at a rate of 1-3℃ / min, and hold for 2-4 hours.

8. A method for high-temperature rapid firing of alumina ceramics according to claim 1 or 5, characterized in that, During the initial densification stage, the temperature is increased to 1450℃ at a rate of 1-3℃ / min, and held for 2-4 hours.

9. A method for high-temperature rapid firing of alumina ceramics according to claim 1 or 5, characterized in that, Grain growth stage: Heat to 1640℃ at a rate of 1-3℃ / min, and hold for 0.5-2 hours.

10. A method for high-temperature rapid firing of alumina ceramics according to claim 1 or 5, characterized in that, Rapid cooling stage: First, the temperature is reduced from the sintering temperature to 1550℃ at a rate of 3-6℃ / min, and held for 8-12 hours. Then, the temperature is reduced from 1550℃ to room temperature at a rate of 1-3℃ / min.

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