Aluminum oxide ceramic product production process

Abstract

The invention discloses a production process of an aluminum oxide ceramic product. The method comprises the following steps: proportioning raw materials; static pressure forming; sintering and molding; and post-processing. According to the raw material ratio, high-purity aluminum oxide powder is selected as a basic raw material, and the purity of the aluminum oxide powder is not lower than 95%. Adding a proper amount of fluxing agent and additive according to the performance requirement of the required ceramic product; the preparation method comprises the following steps: uniformly mixing the raw materials according to a certain proportion, and carrying out refining treatment by adopting a ball milling process for 8-12 hours, so that the average particle size of the raw material particles reaches 0.5-1.5 microns. The preparation method has the beneficial effects that raw material particles are refined by optimizing a raw material formula and adopting a ball milling process, so that the uniformity and the sintering activity of a green body are improved, and the compactness and the mechanical property of a ceramic product are favorably improved; according to the forming technology combining dry pressing forming and isostatic pressing forming, the density and uniformity of the green body are effectively improved, defects in the green body are reduced, and therefore the yield of products is improved.

Description

Technical Field

[0001] The invention relates to the technical field of ceramic product production, in particular to a production process of alumina ceramic products. Background Art

[0002] Alumina ceramics have the advantages of high hardness, good wear resistance and strong chemical stability, and are widely used in machinery, electronics, chemical industry and other fields.

[0003] 1. For example, a Chinese patent discloses a high-strength nano-alumina ceramic product and its preparation process (publication number: CN119390466A), which includes the following preparation steps: mixing alumina powder, composite binder, composite gel, plasticizer, and solvent, ball milling, and obtaining a composite slurry; placing the composite slurry in a mold, performing mold drying, and obtaining a green body; placing the green body in a high-temperature sintering furnace, performing high-temperature sintering, and cooling to room temperature to obtain a nano-alumina ceramic product. Nano-zirconium oxide and nano-magnesium oxide are formed on the surface of pre-treated silicon carbide whiskers. During the sintering process, they can form a solid solution with nano-alumina as a bridge between silicon carbide whiskers and nano-alumina particles, significantly enhancing the binding force of silicon carbide whiskers in the nano-alumina ceramic matrix; phosphoric acid and ammonium aluminum sulfate are firmly bonded to the surface of nano-alumina particles through carboxymethyl cellulose to avoid weak bonding between phosphoric acid and ammonium aluminum sulfate and nano-alumina particles.

[0004] 2. A method for preparing a dense alumina ceramic product (publication number: CN114702307A), which relates to the field of high-temperature ceramics. According to the mass percentage, 10-15% of industrial alumina powder with a particle size of ≤10μm, 5-10% of titanium oxide powder with a particle size of ≤10μm and additives are mixed in a mixer according to a ratio, and then 75-85% of alumina powder with a particle size of ≤30μm is added to the mixer and mixed evenly to form a mixture; 100kg of aqueous solution and 35-50kg of the mixture are added to a stirring barrel, stirred for 2-4 hours to form a slurry; the obtained slurry is injected into a spray granulator, atomized and dried at high speed to form a granulated material, and the granulated material is vacuum-treated, pressurized and sintered; the present invention greatly improves the thermal shock stability of the product, making it a high-density, high-strength and long-life high-temperature ceramic product.

[0005] However, there are some problems with the existing production process of alumina ceramic products. For example, the density of the ceramic products produced is not high enough, which limits their strength and wear resistance; the production process is energy-intensive and costly, affecting the market competitiveness of the products; and some processes are prone to defects during the molding process, reducing the product yield.

[0006] Therefore, it is necessary to propose a production process of alumina ceramic products in view of the above technical problems. Summary of the invention

[0007] The purpose of the present invention is to provide a production process for alumina ceramic products. By optimizing raw material selection, molding method, sintering process and post-processing process, the problems of low density, high cost and low yield rate in the existing process are solved, the comprehensive performance of alumina ceramic products is improved, the production cost is reduced and the competitiveness of the products in the market is enhanced.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] A production process of alumina ceramic products, the method steps are:

[0010] S1, raw material ratio;

[0011] S2, static pressure forming;

[0012] S3, sintering;

[0013] S4. Post-processing.

[0014] The raw material ratio is as follows: high-purity alumina powder is selected as the basic raw material, and its purity is not less than 95%. According to the performance requirements of the required ceramic products, appropriate amounts of flux and additives are added; the raw materials are mixed evenly in a certain proportion, and the ball milling process is used for refinement. The ball milling time is 8-12 hours, so that the average particle size of the raw material particles reaches 0.5-1.5μm.

[0015] In the static pressing forming of step S2, a proper amount of binder is added to the ball-milled raw material, and after being evenly mixed, a blank with a certain fluidity is formed, and the blank is placed in a mold for dry pressing forming, the pressure is controlled at 10-20MPa, and the pressure holding time is 2-5 minutes, and it is initially formed into the desired shape; then, the dry pressed blank is placed in an elastic mold and placed in a high-pressure container for static pressing forming, the pressure is 100-200MPa, and the pressure holding time is 10-20 minutes, so as to further improve the density and uniformity of the blank.

[0016] The further steps of step S3 are: pre-sintering the green body at a temperature of 1000-1200°C, with a heating rate of 5-10°C / min and a holding time of 1-2 hours, so that the binder in the green body can be fully volatilized, and the gas in the green body can be preliminarily removed to form a certain sintering neck; and secondary sintering the pre-sintered green body at a high temperature of 1500-1700°C, with a heating rate of 3-5°C / min and a holding time of 3-5 hours to fully densify the green body. During the sintering process, a certain flow of N2 is introduced to prevent the green body from being oxidized at high temperature.

[0017] Post-processing steps include cutting, grinding, polishing and surface treatment.

[0018] The surface treatment uses chemical vapor deposition (CVD) or physical vapor deposition (PVD) technology to deposit a protective film on the ceramic surface to improve the corrosion resistance and wear resistance of ceramic products.

[0019] Preferably, the flux comprises titanium dioxide (TiO2) and yttrium oxide (Y2O3), and the total addition amount is 4-8wt%.

[0020] The mass ratio of titanium dioxide (TiO2) to yttrium oxide (Y2O3) is (1.5-2):1.

[0021] The binder is polyvinyl alcohol.

[0022] Compared with the prior art, the beneficial effects of the present invention are: by optimizing the raw material formula and refining the raw material particles by ball milling process, the uniformity and sintering activity of the green body are improved, which is beneficial to improving the density and mechanical properties of ceramic products; the forming process combining dry pressing and isostatic pressing effectively improves the density and uniformity of the green body, reduces the defects inside the green body, thereby improving the yield rate of the product.

[0023] The two-step sintering method can not only fully remove the gas and binder in the green body, but also make the green body fully densified at high temperature. At the same time, the introduction of inert gas during the sintering process can effectively prevent the oxidation of the green body and further improve the performance of ceramic products. The mechanical processing and surface treatment in the post-processing process not only ensure the dimensional accuracy and surface quality of the ceramic products, but also improve their corrosion resistance and wear resistance, and broaden the application range of the products. The production process is relatively simple, the energy consumption is low, the production cost is effectively controlled, and it has good economic benefits and market prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the process flow of the present invention. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] The following is combined with Figure 1 The present invention is further described in detail.

[0027] This embodiment provides a technical solution for an alumina granulated powder iron removal device: a production process for an alumina ceramic product, the method steps of which are as follows:

[0028] S1, raw material ratio;

[0029] S2, static pressure forming;

[0030] S3, sintering;

[0031] S4. Post-processing.

[0032] The raw material ratio is as follows: high-purity alumina powder is selected as the basic raw material, and its purity is not less than 95%. According to the performance requirements of the required ceramic products, appropriate amounts of flux and additives are added; the raw materials are mixed evenly in a certain proportion, and the ball milling process is used for refinement. The ball milling time is 8-12 hours, so that the average particle size of the raw material particles reaches 0.5-1.5μm.

[0033] In the static pressing forming of step S2, a proper amount of binder is added to the ball-milled raw material, and after being evenly mixed, a blank with a certain fluidity is formed, and the blank is placed in a mold for dry pressing forming, the pressure is controlled at 10-20MPa, and the pressure holding time is 2-5 minutes, and it is initially formed into the desired shape; then, the dry pressed blank is placed in an elastic mold and placed in a high-pressure container for static pressing forming, the pressure is 100-200MPa, and the pressure holding time is 10-20 minutes, so as to further improve the density and uniformity of the blank.

[0034] The further steps of step S3 are: pre-sintering the green body at a temperature of 1000-1200°C, with a heating rate of 5-10°C / min and a holding time of 1-2 hours, so that the binder in the green body can be fully volatilized, and the gas in the green body can be preliminarily removed to form a certain sintering neck; and secondary sintering the pre-sintered green body at a high temperature of 1500-1700°C, with a heating rate of 3-5°C / min and a holding time of 3-5 hours to fully densify the green body. During the sintering process, a certain flow of N2 is introduced to prevent the green body from being oxidized at high temperature.

[0035] Post-processing steps include cutting, grinding, polishing and surface treatment.

[0036] The surface treatment uses chemical vapor deposition (CVD) or physical vapor deposition (PVD) technology to deposit a protective film on the ceramic surface to improve the corrosion resistance and wear resistance of ceramic products.

[0037] Preferably, the flux comprises titanium dioxide (TiO2) and yttrium oxide (Y2O3), and the total addition amount is 4-8wt%.

[0038] The mass ratio of titanium dioxide (TiO2) to yttrium oxide (Y2O3) is (1.5-2):1.

[0039] The binder is polyvinyl alcohol.

[0040] Compared with the prior art, the beneficial effects of the present invention are: by optimizing the raw material formula and refining the raw material particles by ball milling process, the uniformity and sintering activity of the green body are improved, which is beneficial to improving the density and mechanical properties of ceramic products; the forming process combining dry pressing and isostatic pressing effectively improves the density and uniformity of the green body, reduces the defects inside the green body, thereby improving the yield rate of the product.

[0041] The two-step sintering method can not only fully remove the gas and binder in the green body, but also make the green body fully densified at high temperature. At the same time, the introduction of inert gas during the sintering process can effectively prevent the oxidation of the green body and further improve the performance of ceramic products. The mechanical processing and surface treatment in the post-processing process not only ensure the dimensional accuracy and surface quality of the ceramic products, but also improve their corrosion resistance and wear resistance, and broaden the application range of the products. The production process is relatively simple, the energy consumption is low, the production cost is effectively controlled, and it has good economic benefits and market prospects.

[0042] Embodiment 1:

[0043] Raw material preparation: Select 100g of aluminum oxide powder with a purity of 95%, add 2g of titanium dioxide (TiO2) and 1g of yttrium oxide (Y2O3) as flux and additives. Put the raw materials into a ball mill, add appropriate amounts of ball milling media and dispersant, and mill for 8 hours to obtain a mixed raw material with an average particle size of 0.5μm.

[0044] Molding process: Add 5g of polyvinyl alcohol (PVA) as a binder to the mixed raw materials, mix them thoroughly and evenly to form a blank. Put the blank into a mold, dry press it under a pressure of 10MPa, and hold the pressure for 2 minutes to obtain a preliminary formed blank. Then, put the blank into an elastic mold, place it in a high-pressure container, and perform isostatic pressing at a pressure of 100MPa for 10 minutes.

[0045] Sintering process: Place the isostatically pressed green body into a high-temperature furnace, heat it to 1000°C at a heating rate of 5°C / min, keep it warm for 1 hour for low-temperature pre-sintering, then continue to heat it to 1500°C at a heating rate of 3°C / min, keep it warm for 3 hours for secondary sintering, and introduce nitrogen at a flow rate of 5L / min during the sintering process.

[0046] Post-processing: The sintered ceramic products are subjected to mechanical processing such as cutting, grinding and polishing to achieve the required dimensional accuracy and surface finish. Then, a 0.5μm thick silicon carbide (SiC) protective film is deposited on the ceramic surface using chemical vapor deposition (CVD) technology.

[0047] Embodiment 2:

[0048] Raw material preparation: Select 100g of aluminum oxide powder with a purity of 98%, add 3g of titanium dioxide (TiO2) and 1.5g of yttrium oxide (Y2O3), and ball mill for 10 hours to obtain a mixed raw material with an average particle size of 1μm.

[0049] Molding process: The amount of binder is 6g, the dry pressing pressure is 15MPa, and the holding time is 3 minutes; the isostatic pressing pressure is 150MPa, and the holding time is 15 minutes.

[0050] Sintering process: low-temperature pre-sintering temperature is 1100°C, holding time is 1.5 hours; secondary sintering temperature is 1600°C, holding time is 4 hours, nitrogen flow rate is 8L / min.

[0051] Post-processing process: After machining, a 0.8um thick titanium nitride (TiN) protective film is deposited on the ceramic surface using physical vapor deposition (PVD) technology.

[0052] Comparative Example 1: A conventional single dry pressing process was used, with a molding pressure of 15 MPa and a holding time of 3 minutes. Other conditions were the same as those in Example 1.

[0053] Comparative Example 2: A one-time sintering process was adopted, the sintering temperature was 1600° C., the holding time was 5 hours, and other conditions were the same as those in Example 1.

[0054] Performance test: The performance test was carried out on the alumina ceramic products prepared in Example 1, Example 2, Comparative Example 1 and Comparative Example 2. The test results are shown in the following table:

[0055]

[0056] It can be seen from the test results that the alumina ceramic products prepared by the production process of the present invention are superior to those prepared by the traditional process in terms of density, hardness, bending strength and yield rate.

[0057] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A process for producing alumina ceramic products, characterized in that: The method steps are: S1, raw material ratio; S2, static pressure forming; S3, sintering; S4. Post-processing.

2. The process for producing an alumina ceramic product according to claim 1, characterized in that: The raw material ratio is as follows: high-purity alumina powder is selected as the basic raw material, and its purity is not less than 95%. According to the performance requirements of the desired ceramic products, add appropriate amounts of flux and additives; mix the raw materials evenly in a certain proportion, and use ball milling technology for refinement. The ball milling time is 8-12 hours, so that the average particle size of the raw material particles reaches 0.5-1.5μm.

3. The process for producing an alumina ceramic product according to claim 1, characterized in that: In the static pressing forming of step S2, a proper amount of binder is added to the ball-milled raw material, and after being evenly mixed, a blank with a certain fluidity is formed, and the blank is placed in a mold for dry pressing forming, the pressure is controlled at 10-20MPa, and the pressure holding time is 2-5 minutes, and it is initially formed into the desired shape; then, the dry pressed blank is placed in an elastic mold and placed in a high-pressure container for static pressing forming, the pressure is 100-200MPa, and the pressure holding time is 10-20 minutes, so as to further improve the density and uniformity of the blank.

4. The process for producing an alumina ceramic product according to claim 1, characterized in that: The further steps of step S3 are: pre-sintering the green body at a temperature of 1000-1200°C, with a heating rate of 5-10°C / min and a holding time of 1-2 hours, so that the binder in the green body can be fully volatilized, and the gas in the green body can be preliminarily removed to form a certain sintering neck; and secondary sintering the pre-sintered green body at a high temperature of 1500-1700°C, with a heating rate of 3-5°C / min and a holding time of 3-5 hours to fully densify the green body. During the sintering process, a certain flow of N2 is introduced to prevent the green body from being oxidized at high temperature.

5. The process for producing an alumina ceramic product according to claim 1, characterized in that: Post-processing steps include cutting, grinding, polishing and surface treatment.

6. The process for producing an alumina ceramic product according to claim 1, characterized in that: The surface treatment uses chemical vapor deposition or physical vapor deposition technology to deposit a protective film on the ceramic surface to improve the corrosion resistance and wear resistance of ceramic products.

7. The process for producing an alumina ceramic product according to claim 1, characterized in that: The flux comprises titanium dioxide and yttrium oxide, and the total addition amount is 4-8wt%.

8. The process for producing an alumina ceramic product according to claim 7, characterized in that: The mass ratio of titanium dioxide to yttrium oxide is (1.5-2):

1.

9. The process for producing an alumina ceramic product according to claim 1, characterized in that: The binder is polyvinyl alcohol.

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