A process for the production of ceramic impellers

Abstract

The application relates to a ceramic impeller preparation process and belongs to the technical field of ceramics; the application is characterized in that a polymer binder is prepared, the polymer binder is used for preliminary bonding of alumina powder, the alumina powder is immersed in a sodium hydroxide solution, the alumina powder is bonded again by using a silica sol, high-temperature sintering is carried out, and finally the ceramic impeller is obtained; the quaternary ammonium salt cation in the binder reduces the agglomeration between particles through electrostatic repulsion and enhances the compatibility of the binder with the ceramic powder through interaction; the main chain structure of the polymer binder is damaged through alkali treatment, the flowability between the polymer binder and the ceramic powder is improved, meanwhile, a large number of hydroxyl groups are introduced into the ceramic powder, the hydrogen ions released after ionization of the hydroxyl groups make the surface of the ceramic powder have stronger negative charges, the silica sol and the ceramic alumina generate mullite structures at high temperatures, therefore, the alkali treatment can enhance the interface bonding capacity of the two and avoid the agglomeration of the ceramic powder, and the interface bonding performance and the mechanical properties of the impeller are greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of ceramic technology, specifically relating to a ceramic impeller manufacturing process. Background Technology

[0002] As a high-performance rotating component, the development of impeller manufacturing processes is closely related to the industrial demand for material properties under extreme environments. While advanced ceramic materials possess advantages such as high hardness, high temperature resistance, and corrosion resistance, they also suffer from defects such as low uniformity and low fracture toughness, limiting their application. The bonding process of ceramics is a crucial factor affecting their widespread use. Existing ceramic binders have numerous defects in performance and application. Uneven distribution between the binder and ceramic powder reduces overall bond strength, leading to a decline in the overall performance of the ceramic impeller. Under the centrifugal force generated by high-speed rotation, impeller blades are prone to detachment, or even the entire impeller may shatter. The viscosity of carbon-based polymer binders varies drastically with molecular weight and dosage. Insufficient dosage results in low initial strength of the bonded green body, making it prone to deformation and chipping during transfer or mold disassembly. Excessive dosage leads to high initial viscosity of the slurry, poor fluidity, and difficulty in filling the fine structure of the impeller, easily forming defects such as voids and shrinkage.

[0003] Based on this, the present invention provides a process for manufacturing ceramic impellers. Summary of the Invention

[0004] The purpose of this invention is to provide a ceramic impeller manufacturing process to solve the problems mentioned in the background art.

[0005] The objective of this invention can be achieved through the following technical solutions: A ceramic impeller manufacturing process includes the following steps: Step 1: Under nitrogen protection, unsaturated carboxylic acid, aminopyridine derivative and dimethyl sulfoxide are added to a three-necked flask, a condenser and a thermometer are attached, magnetic stirring is turned on, and the reaction is carried out at 50-60℃ for 1-2 hours. After cooling to room temperature, the polycondensation units are obtained by rotary evaporation and column chromatography. The second step involves adding the polycondensation unit, haloalkanes and acetonitrile into a three-necked flask, attaching a condenser and a thermometer, turning on the magnetic stirrer, and reacting at 50-60°C for 16-24 hours. After the reaction is complete, the solid is rotary evaporated, washed with diethyl ether and filtered. The obtained solid is dried to obtain the ionic monomer. The third step involves adding the ionic monomer, dimethyl sulfoxide, and organic base catalyst to a three-necked flask under nitrogen protection, attaching a condenser and a thermometer, turning on magnetic stirring, and reacting at 50–60°C for 8–12 hours. After the reaction is complete, the flask is washed with diethyl ether and reacted under vacuum for 20–30 minutes. Then, it is transferred to an oven at 80–100°C for 1–2 hours to cure and obtain the polymer binder. Step 4: After mixing alumina powder and ethanol solution, add the mixture to a horizontal ball mill and ball mill for 2-4 hours. Then add polymer binder and ball mill for 5-7 hours. After ball milling, transfer the mixture to sodium hydroxide solution for 30-50 minutes and then add silica sol and ball mill for 4-6 hours. After ball milling, perform spray granulation and machine screening with a 200-300 mesh sieve. The granules that pass through the sieve are the ceramic matrix. Step 5: Inject the ceramic matrix into the injection molding machine at a pressure of 150-250 MPa into the impeller mold, and keep it under this pressure for 5-10 minutes. After cooling to room temperature, demold to obtain the impeller blank. Transfer the impeller blank to a high-temperature box furnace for degreasing under nitrogen protection and high-temperature sintering to obtain the ceramic impeller.

[0006] Furthermore, in the first step, the aminopyridine derivative is one of 2,3-diaminopyridine, 2,4-diaminopyridine, and 2,6-diaminopyridine, and the unsaturated carboxylic acid is one of 4-pentenoic acid, methacrylic acid, and acrylic acid.

[0007] Furthermore, in the first step, the mass ratio of unsaturated carboxylic acid, aminopyridine derivative, and dimethyl sulfoxide is 19.6–21.6:11–13:75–95.

[0008] Furthermore, the general structural formula of the haloalkanes in the second step is: Where n ranges from 1 to 5, and X is either chlorine or bromine.

[0009] Furthermore, in the second step, the mass fraction ratio of the polycondensation unit, the halohydrocarbon, and the acetonitrile is 14–17:10–12:120–160. Furthermore, the organic base catalyst in the third step is at least one of triethylamine, 1,4-diazabicyclooctane, and pyridine.

[0010] Furthermore, in the third step, the mass ratio of the ionic monomer, dimethyl sulfoxide, and organic base catalyst is 12–18: 40–50: 0.6–1.4.

[0011] Furthermore, the vacuum condition in the third step is a vacuum degree of 0.09–0.098 MPa.

[0012] Furthermore, the ethanol solution has a mass fraction of 85-95%.

[0013] Furthermore, the inlet air temperature for spray granulation in the fourth step is 120–160°C.

[0014] Furthermore, in the fourth step, the mass ratio of alumina powder, ethanol solution, and polymer binder is 100–110:130–140:10–20.

[0015] Furthermore, in the fifth step, the injection molding temperature is 160–200°C.

[0016] Furthermore, the mass fraction of the sodium hydroxide solution in step five is 30–50%.

[0017] Furthermore, the degreasing conditions in step five are as follows: raise the temperature to 100–200°C at a heating rate of 1–2°C / min and hold for 2–4 hours; raise the temperature to 200–400°C at a heating rate of 2–3°C / min and hold for 4–6 hours; raise the temperature to 400–600°C at a heating rate of 1.5–2.5°C / min and hold for 2–3 hours.

[0018] Furthermore, the sintering conditions in the fifth step are as follows: raise the temperature to 900–1100°C at a heating rate of 1–2°C / min, hold for 5–7 hours, raise the temperature to 1300–1400°C at a heating rate of 3–4°C / min, hold for 1–2 hours, and finally raise the temperature to 1500–1700°C at a heating rate of 2–3°C / min, hold for 4–6 hours.

[0019] A ceramic impeller preparation process, wherein the ceramic impeller is prepared by any of the above preparation steps.

[0020] The beneficial effects of this invention are: 1) This invention uses unsaturated carboxylic acids and aminopyridine derivatives as raw materials to carry out amidation reaction to obtain polycondensation units. Polycondensation units and halogenated hydrocarbons are used as raw materials to carry out quaternary ammonium salt reaction to obtain ionic monomers. Then, ionic monomers and organic base catalysts are used as raw materials to carry out condensation and curing to obtain polymer binders. Alumina powder, ethanol solution and polymer binders are used as raw materials to carry out ball milling to achieve preliminary bonding. After impregnation treatment with sodium hydroxide solution, silica sol is added and ball milling is continued. After spray granulation and machine screening, ceramic matrix is ​​obtained. Then, ceramic matrix is ​​injection molded, cooled and demolded, degreased and sintered at high temperature to obtain ceramic impellers.

[0021] 2) The quaternary ammonium salt structure in the polymer binder of this invention can be strongly adsorbed onto the surface of ceramic powder particles. Through electrostatic repulsion, it reduces particle agglomeration, resulting in more uniform dispersion of the powder in the binder system. Uniformly dispersed ceramic powder reduces localized particle accumulation, preventing voids after sintering due to uneven particle distribution. The hydrophilic properties of the quaternary ammonium salt cation enhance the compatibility between the binder and the ceramic surface, reducing the risk of cracking and thus maintaining the stability of the interfacial bonding, improving the overall strength, toughness, and reliability of the ceramic impeller.

[0022] 3) In the molding process of this invention, the polymer binder coats the ceramic powder particles, making the originally non-flowable ceramic powder mixture flowable. The high adhesion of the polymer binder can tightly bind the dispersed powder particles. At the same time, the flexibility of its molecular chains can alleviate the stress concentration caused by the molding pressure, thereby significantly enhancing the mechanical strength and toughness of the ceramic impeller.

[0023] 4) The ceramic powder treated with the polymer binder in this invention, through alkaline impregnation, partially disrupts the amide structure in the polymer binder's main chain, reducing the polymer binder's viscosity and improving the flowability between the polymer binder and the ceramic powder. Simultaneously, it introduces more hydroxyl groups onto the ceramic powder surface, significantly increasing the surface hydroxyl density. The surface hydroxyl groups ionize, releasing hydrogen ions, giving the powder surface a stronger negative charge and significantly increasing the electrostatic repulsion between ceramic powder particles. This greatly improves the dispersion stability of the powder in the slurry, thereby enhancing the mechanical properties of the ceramic impeller.

[0024] 5) The silica sol of this invention reacts with alumina in the alumina powder at high temperature to form mullite. Mullite has high hardness, high strength, and good thermal stability, which can effectively enhance the impeller's impact resistance and wear resistance, and provide superior durability. Mullite has a very high melting point and does not easily decompose under high temperature conditions, thus maintaining its structural integrity stably. This allows the impeller to adapt to long-term operation under high-temperature conditions, and the impeller will not be affected by material structure damage under continuous high temperature. Detailed Implementation

[0025] The technical solutions of the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments in this application specification, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection claimed in this application.

[0026] The raw materials used in this invention are not particularly restricted in terms of their source; they can be purchased from the market or prepared using conventional methods known to those skilled in the art.

[0027] Example 1 A ceramic impeller manufacturing process includes the following steps: Step 1: Under nitrogen protection, 19.6 g of 4-pentenoic acid, 11 g of 2,3-diaminopyridine and 75 g of dimethyl sulfoxide were added to a three-necked flask, a condenser and a thermometer were installed, and magnetic stirring was turned on. The reaction was carried out at 50 °C for 2 h and then cooled to room temperature. The polycondensation units were obtained by rotary evaporation and column chromatography. Step 2: Add 14g polycondensation unit, 10g 1-chloropropane and 120g acetonitrile to a three-necked flask, attach a condenser and a thermometer, turn on magnetic stirring, and react at 50℃ for 24h. After the reaction is completed, rotary evaporate, wash with ether and filter. The obtained solid is dried to obtain ionic monomer. The third step involves adding 12g of ionic monomer, 40g of dimethyl sulfoxide, and 0.6g of triethylamine to a three-necked flask under nitrogen protection. A condenser and thermometer are attached, and magnetic stirring is turned on. The mixture is reacted at 50°C for 12 hours. After the reaction is complete, the mixture is washed with diethyl ether and reacted under a vacuum of 0.09MPa for 30 minutes. The mixture is then transferred to an oven and cured at 80°C for 2 hours to obtain the polymer binder. Step 4: Mix 100g of alumina powder and 140g of 85% ethanol solution, then add to a horizontal ball mill and ball mill for 2 hours. Add 10g of polymer binder and continue ball milling for 7 hours. After ball milling, transfer to sodium hydroxide solution for 50 minutes and add 10g of silica sol. Ball mill in a horizontal ball mill for 6 hours. After ball milling, spray granulation is performed at an inlet air temperature of 120℃, and the granules are machine-screened through a 200-mesh sieve. The granules that pass through the sieve are the ceramic matrix. Step 5: Add the ceramic matrix to the injection molding machine and inject it into the mold at an injection pressure of 150 MPa and an injection temperature of 160°C. Maintain this pressure and let it stand for 10 minutes. After cooling to room temperature, demold to obtain the impeller blank. Transfer the impeller blank to a high-temperature box furnace and raise the temperature to 100°C at a heating rate of 1°C / min under nitrogen protection. Hold for 4 hours, raise the temperature to 200°C at a heating rate of 2°C / min, hold for 6 hours, raise the temperature to 400°C at a heating rate of 1.5°C / min, hold for 3 hours for degreasing treatment, raise the temperature to 900°C at a heating rate of 1°C / min, hold for 7 hours, raise the temperature to 1300°C at a heating rate of 3°C / min, hold for 2 hours, and finally raise the temperature to 1500°C at a heating rate of 2°C / min, hold for 6 hours for high-temperature sintering to obtain the ceramic impeller.

[0028] A ceramic impeller preparation process, wherein the ceramic impeller is prepared by the above preparation steps.

[0029] Example 2 A ceramic impeller manufacturing process includes the following steps: Step 1: Under nitrogen protection, 20.6 g of methacrylic acid, 12 g of 2,4-diaminopyridine and 85 g of dimethyl sulfoxide were added to a three-necked flask, a condenser and a thermometer were attached, and magnetic stirring was turned on. The reaction was carried out at 55 °C for 1.5 h and then cooled to room temperature. The polycondensation units were obtained by rotary evaporation and column chromatography. Step 2: Add 15.5g of polycondensation unit, 11.5g of 1-bromopentane and 160g of acetonitrile to a three-necked flask, attach a condenser and a thermometer, turn on magnetic stirring, and react at 55℃ for 20h. After the reaction is completed, rotary evaporate, wash with ether and filter. The obtained solid is dried to obtain the ionic monomer. Step 3: Under nitrogen protection, 15g of ionic monomer, 45g of dimethyl sulfoxide and 1g of 1,4-diazabicyclooctane were added to a three-necked flask, a condenser and a thermometer were installed, and magnetic stirring was turned on. The mixture was reacted at 55°C for 10h. After the reaction was completed, the mixture was washed with diethyl ether and reacted under a vacuum of 0.094MPa for 25min. Then it was transferred to an oven and cured at 90°C for 1.5h to obtain the polymer binder. Step 4: Mix 105g of alumina powder and 135g of 90% ethanol solution, then add to a horizontal ball mill and ball mill for 3 hours. Add 15g of polymer binder and continue ball milling for 6 hours. After ball milling, transfer to sodium hydroxide solution for 40 minutes and add 15g of silica sol. Ball mill in a horizontal ball mill for 5 hours. After ball milling, spray granulation is performed at an inlet air temperature of 140℃, and the granules are machine-sieved through a 250-mesh screen. The sieved granules are the ceramic matrix. Step 5: Add the ceramic matrix to the injection molding machine and inject it into the mold at an injection pressure of 200 MPa and an injection temperature of 180°C. Maintain this pressure and let it stand for 8 minutes. After cooling to room temperature, demold to obtain the impeller blank. Transfer the impeller blank to a high-temperature box furnace and raise the temperature to 150°C at a heating rate of 1.5°C / min under nitrogen protection. Hold for 3 hours, raise the temperature to 300°C at a heating rate of 2.5°C / min, hold for 5 hours, raise the temperature to 500°C at a heating rate of 2°C / min, hold for 2.5 hours for degreasing treatment, raise the temperature to 1000°C at a heating rate of 1.5°C / min, hold for 6 hours, raise the temperature to 1350°C at a heating rate of 3.5°C / min, hold for 1.5 hours, and finally raise the temperature to 1600°C at a heating rate of 2.5°C / min, hold for 5 hours for high-temperature sintering to obtain the ceramic impeller.

[0030] A ceramic impeller preparation process, wherein the ceramic impeller is prepared by the above preparation steps.

[0031] Example 3 A ceramic impeller manufacturing process includes the following steps: Step 1: Under nitrogen protection, 21.6g of acrylic acid, 13g of 2,6-diaminopyridine and 95g of dimethyl sulfoxide were added to a three-necked flask, a condenser and a thermometer were installed, and magnetic stirring was turned on. The mixture was reacted at 60°C for 1 hour and then cooled to room temperature. The polycondensation units were obtained by rotary evaporation and column chromatography. Step 2: Add 17g polycondensation unit, 12g 1-chlorohexane and 160g acetonitrile to a three-necked flask, attach a condenser and a thermometer, turn on magnetic stirring, and react at 60℃ for 16h. After the reaction is completed, rotary evaporate, wash with diethyl ether and filter. The obtained solid is dried to obtain ionic monomer. The third step involves adding 18g of ionic monomer, 50g of dimethyl sulfoxide and 1.4g of pyridine to a three-necked flask under nitrogen protection, attaching a condenser and thermometer, turning on magnetic stirring, and reacting at 60°C for 8 hours. After the reaction is complete, the mixture is washed with diethyl ether and reacted under a vacuum of 0.098MPa for 20 minutes. Then, it is transferred to an oven and cured at 100°C for 1 hour to obtain the polymer binder. Step 4: Mix 110g of alumina powder and 140g of 85% ethanol solution, then add to a horizontal ball mill and ball mill for 2 hours. Add 20g of polymer binder and continue ball milling for 5 hours. After ball milling, transfer to sodium hydroxide solution for 30 minutes and add 20g of silica sol. Ball mill in a horizontal ball mill for 4 hours. After ball milling, spray granulation is performed at an inlet air temperature of 160℃, and the granules are machine-sieved through a 300-mesh screen. The granules that pass through the screen are ceramic matrix materials. Step 5: Add the ceramic matrix to the injection molding machine and inject it into the mold at an injection pressure of 250 MPa and an injection temperature of 200°C. Maintain this pressure and let it stand for 5 minutes. After cooling to room temperature, demold to obtain the impeller blank. Transfer the impeller blank to a high-temperature box furnace and raise the temperature to 200°C at a heating rate of 2°C / min under nitrogen protection. Hold for 2 hours. Raise the temperature to 400°C at a heating rate of 3°C / min and hold for 4 hours. Raise the temperature to 600°C at a heating rate of 2.5°C / min and hold for 2 hours for degreasing. Raise the temperature to 1100°C at a heating rate of 2°C / min and hold for 5 hours. Raise the temperature to 1400°C at a heating rate of 4°C / min and hold for 1 hour. Finally, raise the temperature to 1700°C at a heating rate of 3°C / min and hold for 4 hours for high-temperature sintering to obtain the ceramic impeller.

[0032] A ceramic impeller preparation process, wherein the ceramic impeller is prepared by the above preparation steps.

[0033] Comparative Example 1 The difference between this comparative example and Example 2 is that no polymer binder is prepared, while the other raw materials and preparation steps remain unchanged.

[0034] Experimental Example 1 The ceramic impellers in Examples 1-3 and Comparative Example 1 were subjected to performance tests. The interfacial shear strength of each group of ceramic impellers was tested according to GB / T31541-2015 "Test Method for Tensile and Shear Bond Strength of Fine Ceramics", the flexural strength of each group of ceramic impellers was tested according to GB / T6569-2023 "Test Method for Bending Strength of Fine Ceramics", and the fracture toughness of each group of ceramic impellers was tested according to GB / T44547-2024 "Test Method for Fracture Toughness of Fine Ceramics". The test results are shown in Table 1.

[0035] Table 1 As can be seen from Table 1, Examples 1-3 have higher interfacial shear strength and fracture toughness compared with Comparative Example 1, indicating that the interfacial bonding ability, deformation resistance and toughness of Examples 1-3 are better than those of Comparative Example 1. Combined with Comparative Example 1, it can be seen that the interfacial bonding ability, deformation resistance and toughness of ceramic impellers can be effectively improved by polymer binder and alkaline treatment.

[0036] The above provides a detailed description of a ceramic impeller manufacturing process provided by the present invention. Specific examples have been used to illustrate the principles and implementation methods of the invention. The descriptions of these embodiments are merely for the purpose of helping to understand the method and core ideas of the present invention, including the best mode, and also to enable any person skilled in the art to practice the present invention, including manufacturing and using any device or system, and implementing any combination method. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from its principles. In particular, as long as there is no structural conflict, the features in the embodiments disclosed in this invention can be combined with each other in any way. The lack of an exhaustive description of these combinations in this specification is merely for the sake of brevity and resource conservation. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A process for manufacturing ceramic impellers, characterized in that, Includes the following steps: Preparation of the polymer binder: Amidation reaction of unsaturated carboxylic acid and aminopyridine derivatives yields condensation units, with a mass ratio of unsaturated carboxylic acid, aminopyridine derivative, and dimethyl sulfoxide of 19.6–21.6:11–13:75–95. A quaternary ammonium salt reaction is then carried out between the condensation units and haloalkanes to obtain ionic monomers, with a mass ratio of condensation units, haloalkanes, and acetonitrile of 14–17:10–12:120–160. Finally, the polymer binder is obtained by condensation and curing of the ionic monomers with an organic base catalyst, with a mass ratio of ionic monomers, dimethyl sulfoxide, and organic base catalyst of 12–18:40–50:0.6–1.

4. Preparation of ceramic impeller: Alumina powder, ethanol solution, and polymer binder are ball-milled for preliminary bonding, then impregnated with sodium hydroxide solution. Silica sol is then added and ball-milled again. The mixture is then spray-granulated and machine-sieved to obtain ceramic matrix. The ceramic matrix is ​​then injection-molded, cooled, demolded, degreased, and sintered at high temperature to obtain the ceramic impeller. The mass ratio of alumina powder, ethanol solution, polymer binder, and silica sol is 100–110:130–140:10–20:10–20. The ethanol solution has a mass fraction of 85-95%, and the sodium hydroxide aqueous solution has a mass fraction of 30-50%. The aminopyridine derivative is at least one of 2,3-diaminopyridine, 2,4-diaminopyridine, and 2,6-diaminopyridine, and the unsaturated carboxylic acid is one of 4-pentenoic acid, methacrylic acid, and acrylic acid.

2. The ceramic impeller manufacturing process according to claim 1, characterized in that, The general structural formula of haloalkanes is Where n ranges from 1 to 5, and X is either chlorine or bromine.

3. The ceramic impeller manufacturing process according to claim 1, characterized in that, The sintering conditions are as follows: raise the temperature to 850–900℃ at a heating rate of 1–2℃ / min, hold for 5–7 hours, raise the temperature to 1150–1200℃ at a heating rate of 3–4℃ / min, hold for 1–2 hours, and finally raise the temperature to 1450–1500℃ at a heating rate of 4.5–5.5℃ / min, hold for 2–3 hours.

4. The ceramic impeller manufacturing process according to claim 1, characterized in that, The degreasing conditions are as follows: raise the temperature to 100-200℃ at a heating rate of 1-2℃ / min and hold for 2-4 hours; raise the temperature to 200-400℃ at a heating rate of 2-3℃ / min and hold for 4-6 hours; raise the temperature to 400-600℃ at a heating rate of 1.5-2.5℃ / min and hold for 2-3 hours.

5. The ceramic impeller manufacturing process according to claim 1, characterized in that, The inlet air temperature for spray granulation is 120–160℃.

6. The ceramic impeller manufacturing process according to claim 1, characterized in that, The injection molding temperature is 160–200℃.

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