Preparation method of ceramic twist-resistant head for rotor spinner

Abstract

The invention discloses a preparation method of a ceramic twist-resistant head for a rotor spinner. The method specifically comprises the following steps: preparing high-purity alumina powder; manufacturing a green body of the high-purity aluminum oxide ceramic twist-resistant head, wherein a binder is added for mixing; purification treatment of the preformed blank of the twist-resistant head: adding a purifying agent 1 for primary purification, drying in the shade, drying and pre-sintering; adding a purifying agent 2 for secondary purification, drying in the shade, drying and presintering; carrying out doping treatment on the preformed blank of the twist-resistant head, wherein the blank body is immersed in a magnesium nitrate solution; the invention discloses a two-step sintering process of a ceramic twist-resistant head. The process comprises the following steps: heating, cooling, preserving heat, cooling to room temperature along with a furnace, and opening the furnace; and machining and polishing the ceramic anti-twisting head. The invention has the beneficial effects of high density, fine grains, high heat conductivity coefficient and few surface pores; the surface is smooth without burrs and air holes; the friction coefficient is small; the hardness is high and the wear-resisting property is good; the heat conductivity is good.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ceramic materials, in particular to a preparation method of a ceramic twist stopper for an air spinning machine. BACKGROUND

[0002] Air spinning (also known as rotor spinning) is a new type of spinning form. In air spinning, feeding, carding and crimping are the results of the combined action of mechanical movement and airflow. The principle of yarn formation is discontinuity of input and output of fibers, one end of which is held and the other end is twisted. The main element of twisting is the twist stopper. The shape, size and material of the twist stopper and the manufacturing process have a great influence on the quality of the formed yarn. The twist stopper is located between the fiber conveying channel of the spinning device and the yarn guiding device, which is the end point of the fiber and the starting point of the yarn. The uniformly arranged fibers move and twist on the twist stopper under the drafting action of the yarn guide, and the yarn is output. The main functions are to add a certain twist to the yarn and minimize twist loss, and to ensure the rapid movement of fibers during yarn conveying.

[0003] Currently, most twist stoppers on the market are made of metal materials. The hardness is improved through heat treatment, and then the required size and shape are obtained through mechanical processing. Then, the twist stopper with smooth surface, shape and size meeting the requirements is obtained through polishing. Since the raw material of the metal twist stopper is cheap, easy to process and has good heat conductivity, many air spinning equipment manufacturers use metal twist stoppers. However, with the progress of air spinning technology, the rotation speed of the spinning cup is getting higher and higher, and the relative speed of the twist stopper and the yarn is getting faster and faster. The problem of friction and wear of the twist stopper is getting more and more serious. The metal twist stopper cannot meet the requirements of high-speed rotor spinning.

[0004] Since the ceramic twist stopper has high added value and a large market size, ceramic manufacturers have successively developed ceramic twist stoppers. However, the currently produced alumina ceramic twist stopper has a rough surface, many pits and pores after polishing, and a roughness that does not meet the requirements. The product color is yellowish, not semi-transparent, the thermal conductivity is low, the yarn is easily burned during use, the produced yarn has many hairs, and the service life is not high. SUMMARY

[0005] The present application is to overcome the above-mentioned deficiencies in the prior art, and provides a preparation method of a ceramic twist stopper for an air spinning machine, which has high density, fine grain, high thermal conductivity and few surface pores.

[0006] In order to achieve the above-mentioned purpose, the present application adopts the following technical scheme:

[0007] A preparation method of a ceramic twist stopper for an air spinning machine, specifically comprising the following steps:

[0008] (1) Preparation of high-purity alumina powder: High-purity metallic aluminum is reacted with dilute hydrochloric acid, and the obtained aluminum chloride is purified to remove impurities after filtration to obtain aluminum chloride solution. High-purity aluminum chloride powder is obtained by multiple vacuum distillations. The aluminum chloride vapor is heated and passed into an alumina ceramic combustion tower, and then hydrogen and oxygen are introduced for combustion to obtain aluminum hydroxide particles. The particles are added to a reaction vessel lined with polytetrafluoroethylene, deionized water is added, and the mixture is stirred to form aluminum hydroxide sol. The alumina crystals are precipitated by heating, filtered, calcined at low temperature, and crushed to obtain high-purity alumina powder.

[0009] (2) Preparation of high-purity alumina ceramic anti-twisting head green body: The high-purity alumina powder obtained by spray drying is added to the internal mixer, then the binder is added for mixing, cooling, and crushing into small pieces. The green body is then placed in the injection molding machine, fitted with a coffee machine puncture needle mold, and injection molded to obtain the ceramic anti-twisting head green body. The molded ceramic anti-twisting head green body is then placed in a medium-temperature degreasing furnace to remove the organic binder and complete the pre-sintering.

[0010] (3) Purification treatment of anti-twist head preform: Place the pre-fired anti-twist head preform into a clean plastic screen, then put the screen into a circulating water tank, add purifying agent 1 into the water tank, and circulate purifying agent 1 through the plastic screen. Place the preform after purification treatment into a flowing deionized water tank. Take the preform after the first purification from the plastic screen and place it into a clean enamel tray. First, air dry at room temperature, then put it into an oven. Place the thoroughly dried preform into a muffle furnace for further pre-firing. Place the pre-fired anti-twist head preform into a clean plastic screen, then put the screen into a circulating water tank, add purifying agent 2 into the water tank, and circulate purifying agent 2 through the plastic screen. Place the preform after purification treatment into a flowing deionized water tank. Take the preform after the second purification from the plastic screen and place it into a clean enamel tray. First, air dry at room temperature, then put it into an oven.

[0011] (4) Doping treatment of anti-twisting head preform: dissolve magnesium nitrate in deionized water to form a solution, then immerse the pre-fired alumina blank in the magnesium nitrate solution, take out the blank and let it air dry naturally, and then place it in an oven;

[0012] (5) Two-step sintering process of ceramic anti-twisting head: The purified and dried anti-twisting head blank is placed in a vacuum furnace, heated first and then cooled down, and kept at the temperature before being cooled to room temperature and then the furnace is opened to obtain alumina ceramic anti-twisting head blank.

[0013] (6) Machining and polishing of ceramic anti-twisting head: The sintered anti-twisting head blank is ground in length and outer diameter using a diamond grinding wheel, and then the working part of the anti-twisting head surface is polished using diamond polishing paste to obtain a high-purity, high-thermal-conductivity fine-grained alumina ceramic anti-twisting head finished product.

[0014] To process alumina powder into a twist-resistant head shape, it must possess flowability. For alumina ceramics, purity and grain structure, especially grain size and morphology, play a crucial role in optimizing physical properties. Most importantly, purity affects grain boundary chemistry, thus influencing grain boundary strength. Grain size and morphology strongly affect sintering performance, thereby affecting achievable density, structure, and the strength and semi-permeability of components in the final product. Typical contaminants in alumina are Si, Ca, Na, K, and Fe, which accelerate grain growth and reduce grain boundary strength. Simultaneously, these impurity elements form a glassy phase at alumina grain boundaries, encapsulating the alumina grains and reducing the thermal conductivity of alumina ceramics. This invention optimizes the injection molding formula to increase feed flowability and shape retention, ensuring good mold filling performance. It improves the purity of polycrystalline metal oxides by adding organic or inorganic substances to water-based and dispersant-based formulations. Magnesium oxide significantly aids in the sintering of alumina ceramics, lowering the sintering temperature, increasing grain boundary strength, and promoting the elimination of intergranular pores during sintering. This invention introduces magnesium oxide in the form of magnesium nitrate, allowing it to uniformly coat the alumina grains as magnesium nitrate by immersing the pre-fired green body in a magnesium-containing solution. This promotes sintering without creating an excess glass phase due to magnesium oxide accumulation at grain boundaries. Furthermore, the vacuum atmosphere facilitates oxygen ion diffusion, increasing the diffusion rate of pores in the ceramic green body and reducing porosity. The two-step sintering process yields high-density, fine-grained alumina ceramics.

[0015] Preferably, the specific operation method in step (1) is as follows:

[0016] (11) React excess high-purity metallic aluminum with 20% dilute hydrochloric acid, filter, and then purify the obtained aluminum chloride by using ion exchange resin and activated carbon to remove impurities, and obtain aluminum chloride solution.

[0017] (12) The obtained aluminum chloride solution was repeatedly distilled under reduced pressure to obtain high-purity aluminum chloride powder;

[0018] (13) The obtained high-purity aluminum chloride powder is heated to 300°C to form aluminum chloride vapor. The aluminum chloride vapor is passed into a combustion tower lined with 99% alumina ceramic, and then hydrogen and oxygen are passed in for combustion. Aluminum hydroxide particles are obtained by gas phase precipitation.

[0019] (14) Add the obtained aluminum hydroxide particles to a reaction vessel lined with polytetrafluoroethylene, add deionized water, stir to form aluminum hydroxide sol, and then heat to 95-100 degrees Celsius and pressure 0.8-2 MPa to precipitate aluminum oxide grains.

[0020] (15) After pressure filtration, the alumina is calcined at low temperature and crushed to obtain 99.99% high-purity alumina powder with high purity, ultrafine texture and few hard agglomerates.

[0021] Preferably, in step (13), the molar ratio of aluminum chloride vapor: hydrogen: oxygen is 5:3:1-2:5:3.

[0022] Preferably, the specific operation method in step (2) is as follows:

[0023] (21) Weigh 10 kg of the high-purity alumina ceramic powder obtained by spray drying and add it to the internal mixer. Then add the binder and mix for 120-180 min. The rotor speed of the mixer is 50-70 r / min.

[0024] (22) After the well-mixed feed is cooled, it is broken into small pieces, put into the injection molding machine, and the coffee machine piercing needle mold is installed. The injection molding is performed to obtain the ceramic anti-twist head green body. The injection temperature is 165-190℃, the injection pressure is 50-80MPa, and the injection speed is 50-100mm / s.

[0025] (23) Place the formed ceramic anti-twist head green body into a medium-temperature degreasing furnace to remove the organic binder and complete the pre-sintering, so that the green body has a certain strength for subsequent purification treatment. The heating curve is as follows: room temperature - 100℃, 2-5℃ / min; 100-250℃, 0.5-2℃ / min; 250-450℃, 1-2℃ / min; 450-750℃, 3-5℃ / min; 750℃ for 1-3 hours.

[0026] Among them, by optimizing the injection formulation, the feed flowability and shape retention are increased, ensuring good mold filling performance. Under a microscope, the surface of the green body of the anti-twist head is smooth, without air holes, water marks, or shrinkage cavities caused by heat shrinkage.

[0027] Preferably, in step (2), the adhesive comprises the following components by mass percentage: 10-20 wt% paraffin wax, 5-10 wt% food wax, 40-50 wt% acrylic resin, 10-20 wt% PVB resin, 10-20 wt% LLDPE, 2-5 wt% EVA, 1-5 wt% behenic acid, and 1-5 wt% monoglyceride.

[0028] Preferably, the specific operation method in step (3) is as follows:

[0029] (31) Place the pre-fired anti-twist head blank into a clean plastic screen, then put the screen into a circulating water tank, put purification agent 1 into the water tank, and circulate the purification agent 1 through the plastic screen for 5-10 hours.

[0030] (32) Place the purified blank into a flowing deionized water tank to further remove metal ion impurities and the penetrating purification agent 1 for 2-6 hours.

[0031] (33) Take the purified green body out of the plastic screen and put it into a clean enamel plate. First, air dry it at room temperature for 15-30 hours, and then put it into an oven. First, dry it at 50-80℃ for 1-3 hours, and then dry it at 120℃ for 2-5 hours.

[0032] (34) Place the thoroughly dried preform into a muffle furnace and continue pre-firing. The heating curve is as follows: room temperature - 100℃, 2-5℃ / min; 100-250℃, 0.5-2℃ / min; 250-450℃, 1-2℃ / min; 450-750℃, 3-5℃ / min; 1050℃ for 1-3 hours.

[0033] (35) Place the pre-fired twist-resistant head blank into a clean plastic screen, then put the screen into a circulating water tank, add purifying agent 2 into the water tank, and circulate purifying agent 2 through the plastic screen for 5-10 hours.

[0034] (36) Place the purified blank into a flowing deionized water tank to further remove the metal ion impurities remaining during the secondary purification and the purified agent 2 that has been introduced, for a time of 2-6 hours.

[0035] (37) Take the purified green body out of the plastic screen and put it into a clean enamel plate. First, air dry it at room temperature for 15-30 hours, and then put it into an oven. First, dry it at 50-80℃ for 1-3 hours, and then dry it at 120℃ for 2-5 hours.

[0036] This invention improves the purity of polycrystalline metal oxides by adding organic or inorganic substances to water-based and dispersant-based materials. These organic or inorganic substances absorb unwanted impurities in subsequent processes and transport them to the component surface. It has been shown that components based on fine powders, with an average particle size of less than 1 μm, provide better cleaning than those with coarse particles. Solvent media can include deionized water, alcohol, ketones, etc. Purifying agents can be diluted acids and bases, such as NH4OH and HCl, as well as H3PO4, HNO3, etc. Purification can be facilitated by the capillary effect within the component.

[0037] Preferably, in step (3), the purifying agent 1 is composed of deionized water, CE64 dispersant, and 20% analytical grade HCl solution, wherein the 20% analytical grade HCl solution refers to a 10% HCl + 10% HNO3 solution. The composition ratio of the purifying agent 1 is: 60%-70% deionized water, 0.5-2% CE64 dispersant, and 30%-40% 20% analytical grade HCl solution.

[0038] Preferably, in step (3), the purifying agent 2 is composed of anhydrous ethanol, D-305 dispersant, and 25% NH3·H2O solution. The composition ratio of the purifying agent 2 is: 70%-85% anhydrous ethanol, 0.5-2% D-305 dispersant, and 18%-40% 25% NH3·H2O solution.

[0039] Preferably, in step (4), the specific operation method is as follows: magnesium nitrate is dissolved in deionized water to form a solution with a concentration of 0.05-0.2 mol / L. Then, the pre-calcined alumina blank is immersed in the magnesium nitrate solution for 3-6 hours. After removing the blank, it is first naturally air-dried, and then placed in an oven and baked at 110-140℃ for 2-5 hours. In this invention, magnesium oxide is introduced in the form of magnesium nitrate. By immersing the pre-calcined blank in a magnesium-containing solution, magnesium is uniformly coated on the surface of the alumina grains in the form of magnesium nitrate. By adjusting the magnesium nitrate concentration and immersion time, the amount of magnesium doping can be adjusted, which promotes sintering and prevents the formation of excess glass phase due to magnesium oxide accumulation at grain boundaries.

[0040] Preferably, in step (5), the specific operation method is as follows: the purified and dried anti-twisting head blank is placed in a vacuum furnace and heated to 1550-1600℃ at a heating rate of 5-15℃ / min, then cooled to 1450-1500℃ at a rate of 3-10℃ / min and held for 5-12 hours. After cooling to room temperature in the furnace, the furnace is opened to obtain an alumina ceramic anti-twisting head blank. In this invention, the inventors discovered through exploration that densification has already begun in the temperature range of 20-50℃ below the highest sintering temperature, while grain boundary movement has not yet been activated. The temperature point at which densification begins is set as T1. When the temperature reaches T1, it is lowered to a temperature T2 that is 100-150℃ below the highest sintering temperature at a certain cooling rate. The temperature T2 is held for a relatively long time, 5-12 hours. Sintering in this temperature range leads to the elimination of residual porosity without the final stage of grain growth. Using this sintering process, high-density, fine-grained alumina ceramics can be obtained.

[0041] The beneficial effects of this invention are: high density, fine grains, high thermal conductivity, and few surface pores; smooth surface, free of burrs and pores, which does not affect the movement of the yarn on the surface of the twist-stopping head; a low coefficient of friction, which ensures both high-speed movement of the fiber on the arc surface of the twist-stopping head and the degree of twisting; high hardness and good wear resistance, preventing grooves or shedding from affecting the movement and surface quality of the yarn; high density and good thermal conductivity, which can release the heat generated by the friction between the yarn and the surface of the twist-stopping head in a short time, so as not to affect the quality of the yarn. Attached Figure Description

[0042] Paraffin wax This is a scanning electron microscope image of the ceramic in Embodiment 1 of the present invention;

[0043] Food wax This is a scanning electron microscope image of the ceramic in Embodiment 2 of the present invention;

[0044] Acrylic resin This is a scanning electron microscope image of the ceramic in Embodiment 3 of the present invention. Detailed Implementation

[0045] The present invention will now be further described with reference to the accompanying drawings and specific embodiments.

[0046] To process alumina powder into the shape of a twist-resistant head, it must be made fluid. This is typically achieved by adding a polymer-containing organic medium to the powder and then mixing it in an internal mixer or kneader to form a dough-like substance for processing during injection molding. Since the rotors and internal cavities of the internal mixer or kneader are made of metal, it is difficult to avoid the introduction of metal impurities during the hours-long mixing process. Simultaneously, the injection molding machine used for molding, with its screw and barrel also made of metal, although treated with material selection and work hardening, still lacks the surface hardness and wear resistance of ceramic powder, thus leading to the introduction of metal impurities during injection molding. Finally, the injection molding die for the twist-resistant head is also made of metal; the high-purity alumina feed melt continuously impacts and rubs against the die under high temperature and pressure, again introducing metal impurities into the final product. For alumina ceramics, purity and grain structure, especially grain size and morphology, play a crucial role in optimizing physical properties. Most importantly, purity affects grain boundary chemistry, thus influencing grain boundary strength. Grain size and morphology strongly affect sintering performance, thereby impacting achievable density, structure, and the strength and translucency of components in the final product. Typical contaminants in zirconia and alumina are Si, Ca, Na, K, and Fe, which accelerate grain growth and reduce grain boundary strength. Simultaneously, these impurity elements form a glassy phase at alumina grain boundaries, encapsulating the alumina grains and reducing the thermal conductivity of alumina ceramics. Therefore, high-purity alumina ceramics with near-theoretical density (3.985 g / m³) can achieve a thermal conductivity of 33 W / m·K, while 92% alumina ceramics (i.e., 92% alumina content) have a thermal conductivity of less than 20 W / m·K. Ultimately, ceramic twisting heads manufactured using conventional alumina ceramic injection molding processes tend to be yellowish or pinkish in color, have coarser grains, more pores, lower thermal conductivity, and poor transparency.

[0047] Several requirements for the anti-twist head in air-jet spinning: 1. Smooth surface, free of burrs and pores; otherwise, it will snag the yarn and affect the movement of the yarn on the anti-twist head surface. 2. Low coefficient of friction; this ensures both high-speed fiber movement on the arc surface of the anti-twist head and the degree of twisting. 3. Good abrasion resistance; prevents grooves or shedding that could affect yarn movement and surface quality. 4. Good thermal conductivity; able to release the heat generated by friction between the yarn and the anti-twist head surface in a short time, thus avoiding any impact on yarn quality.

[0048] Therefore, the present invention provides a method for preparing a ceramic twist-blocking head for an air-jet spinning machine, specifically including the following steps:

[0049] (1) Preparation of high-purity alumina powder: High-purity metallic aluminum is reacted with dilute hydrochloric acid, and the resulting aluminum chloride is purified to remove impurities after filtration to obtain an aluminum chloride solution. This solution is then subjected to multiple vacuum distillations to obtain high-purity aluminum chloride powder. The powder is heated to produce aluminum chloride vapor, which is then introduced into an alumina ceramic combustion tower. Hydrogen and oxygen are then introduced for combustion to obtain aluminum hydroxide particles. These particles are added to a polytetrafluoroethylene-lined reactor, along with deionized water, and stirred to form an aluminum hydroxide sol. The sol is heated to precipitate alumina crystals, which are then filtered, calcined at low temperature, and crushed to obtain high-purity alumina powder. The specific operation method is as follows:

[0050] (11) React excess high-purity metallic aluminum with 20% dilute hydrochloric acid, filter, and then purify the obtained aluminum chloride by using ion exchange resin and activated carbon to remove impurities, and obtain aluminum chloride solution.

[0051] (12) The obtained aluminum chloride solution was repeatedly distilled under reduced pressure to obtain high-purity aluminum chloride powder;

[0052] (13) The obtained high-purity aluminum chloride powder is heated to 300°C to form aluminum chloride vapor. The aluminum chloride vapor is passed into a combustion tower lined with 99% alumina ceramic, and then hydrogen and oxygen are passed in for combustion. Aluminum hydroxide particles are obtained by gas phase precipitation. The molar ratio of aluminum chloride vapor: hydrogen: oxygen is 5:3:1-2:5:3.

[0053] (14) Add the obtained aluminum hydroxide particles to a reaction vessel lined with polytetrafluoroethylene, add deionized water, stir to form aluminum hydroxide sol, and then heat to 95-100 degrees Celsius and pressure 0.8-2 MPa to precipitate aluminum oxide grains.

[0054] (15) After pressure filtration, the alumina is calcined at low temperature and crushed to obtain 99.99% high-purity alumina powder with high purity, ultrafine texture and few hard agglomerates.

[0055] (2) Preparation of high-purity alumina ceramic anti-twist head green body: The high-purity alumina powder obtained by spray drying is added to a mixer, then a binder is added for mixing, cooling, and crushing into small pieces. The pieces are then placed in an injection molding machine, fitted with a coffee machine puncture needle mold, and injection molded to obtain a ceramic anti-twist head green body. The molded ceramic anti-twist head green body is then placed in a medium-temperature degreasing furnace to remove the organic binder and complete the pre-sintering. The specific operation method is as follows:

[0056] (21) Weigh 10 kg of the high-purity alumina ceramic powder obtained by spray drying and add it to a mixer. Then add the binder and mix for 120-180 min. The rotor speed of the mixer is 50-70 r / min. The binder is composed of the following components by mass percentage: paraffin wax 10-20 wt%, food wax 5-10 wt%, acrylic resin 40-50 wt%, PVB resin 10-20 wt%, LLDPE 10-20 wt%, EVA 2-5 wt%, behenic acid 1-5 wt%, and monoglyceride 1-5 wt%.

[0057] PVB resin LLDPE EVA Behenic acid Monoglyceride Content wt% Deionized water CE64 dispersant 10% HCL + 10% HNO3 solution 10-20 5-10 40-50 10-20 10-20 2-5 1-5 1-5

[0058] (22) After the well-mixed feed is cooled, it is broken into small pieces, put into the injection molding machine, and the coffee machine piercing needle mold is installed for injection molding to obtain the ceramic anti-twist head green body. The injection temperature is 165-190℃, the injection pressure is 50-80MPa, and the injection speed is 50-100mm / s. By optimizing the injection formula, the feed fluidity and shape retention are increased, ensuring good mold filling performance. Under the microscope, the surface of the anti-twist head green body is smooth, without air holes, water marks, or shrinkage cavities caused by heat shrinkage.

[0059] (23) Place the formed ceramic anti-twist head green body into a medium-temperature degreasing furnace to remove the organic binder and complete the pre-sintering, so that the green body has a certain strength for subsequent purification treatment. The heating curve is as follows: room temperature - 100℃, 2-5℃ / min; 100-250℃, 0.5-2℃ / min; 250-450℃, 1-2℃ / min; 450-750℃, 3-5℃ / min; 750℃ for 1-3 hours.

[0060] (3) Purification treatment of the anti-twisting head preform: Place the pre-fired anti-twisting head preform into a clean plastic screen, then place the screen into a circulating water tank containing purifying agent 1. Purifying agent 1 circulates through the plastic screen. Place the purified preform into a flowing deionized water tank. Remove the preform after the first purification from the plastic screen and place it into a clean enamel tray. Air dry at room temperature, then place it in an oven. Place the thoroughly dried preform into a muffle furnace for further pre-firing. Place the pre-fired anti-twisting head preform into a clean plastic screen, then place the screen into a circulating water tank containing purifying agent 2. Purifying agent 2 circulates through the plastic screen. Place the purified preform into a flowing deionized water tank. Remove the preform after the second purification from the plastic screen and place it into a clean enamel tray. Air dry at room temperature, then place it in an oven. The specific operation method is as follows:

[0061] (31) Place the pre-fired twist-resistant head blank into a clean plastic screen, and then put the screen into a circulating water tank. Add purifying agent 1 to the water tank. Purifying agent 1 circulates through the plastic screen. The purpose of using a circulating water tank is that after purifying agent 1 dissolves the impurities in the blank, it can quickly carry the impurities out of the pre-made blank. The purification treatment time is 5-10 hours. Purifying agent 1 is composed of deionized water, CE64 dispersant, and 20% analytical grade HCl solution. The 20% analytical grade HCl solution refers to 10% HCl + 10% HNO3 solution. The composition ratio of purifying agent 1 is as follows: 60%-70% deionized water, 0.5-2% CE64 dispersant, and 30%-40% 20% analytical grade HCl solution.

[0062] Ratio Anhydrous ethanol D-305 dispersant 25% NH3.H2O solution 60％-70％ 0.5-2％ 30％-40％

[0063] (32) Place the purified blank into a flowing deionized water tank to further remove metal ion impurities and the penetrating purification agent 1 for 2-6 hours.

[0064] (33) Take the purified green body out of the plastic screen and put it into a clean enamel plate. First, air dry it at room temperature for 15-30 hours, and then put it into an oven. First, dry it at 50-80℃ for 1-3 hours, and then dry it at 120℃ for 2-5 hours.

[0065] (34) Place the thoroughly dried preform into a muffle furnace and continue pre-firing. The heating curve is as follows: room temperature - 100℃, 2-5℃ / min; 100-250℃, 0.5-2℃ / min; 250-450℃, 1-2℃ / min; 450-750℃, 3-5℃ / min; 1050℃ for 1-3 hours.

[0066] (35) Place the pre-fired twist-resistant head blank into a clean plastic screen, and then put the screen into a circulating water tank. Add purifying agent 2 to the water tank. The purifying agent 2 circulates through the plastic screen. The purpose of using the circulating water tank is that after the purifying agent 2 dissolves the impurities in the blank, it can quickly carry the impurities out of the pre-made blank. The purification treatment time is 5-10 hours. Purifying agent 2 is composed of anhydrous ethanol, D-305 dispersant, and 25% NH3.H2O solution. The composition ratio of purifying agent 2 is as follows: anhydrous ethanol 70%-85%, D-305 dispersant 0.5-2%, and 25% NH3.H2O solution 18%-40%.

[0067] Ratio Paraffin wax Food wax Acrylic resin 70％-85％ 0.5-2％ 18％-40％

[0068] (36) Place the purified blank into a flowing deionized water tank to further remove the metal ion impurities remaining during the secondary purification and the purified agent 2 that has been introduced, for a time of 2-6 hours.

[0069] (37) Take the purified green body out of the plastic screen and put it into a clean enamel plate. First, air dry it at room temperature for 15-30 hours, and then put it into an oven. First, dry it at 50-80℃ for 1-3 hours, and then dry it at 120℃ for 2-5 hours.

[0070] This invention improves the purity of polycrystalline metal oxides by adding organic or inorganic substances to water-based and dispersant-based materials. These organic or inorganic substances absorb unwanted impurities in subsequent processes and transport them to the component surface. It has been shown that components based on fine powders, with an average particle size of less than 1 μm, provide better cleaning than those with coarse particles. Solvent media can include deionized water, alcohol, ketones, etc. Purifying agents can be diluted acids and bases, such as NH4OH and HCl, as well as H3PO4, HNO3, etc. Purification can be facilitated by the capillary effect within the component.

[0071] (4) Doping treatment of anti-twisting head preform: dissolve magnesium nitrate in deionized water to form a solution, then immerse the pre-fired alumina preform in the magnesium nitrate solution. After taking out the preform, let it air dry naturally, and then place it in an oven. The specific operation method is as follows: dissolve magnesium nitrate in deionized water to form a solution with a concentration of 0.05-0.2 mol / L, then immerse the pre-fired alumina preform in the magnesium nitrate solution for 3-6 hours. After taking out the preform, let it air dry naturally, and then place it in an oven and bake at 110-140℃ for 2-5 hours.

[0072] Magnesium oxide has a significant sintering-aiding effect on alumina ceramics, lowering the sintering temperature, increasing grain boundary strength, and promoting the elimination of intergranular pores during sintering. However, magnesium oxide is usually introduced into alumina in the form of particles or magnesium sol. While this promotes the sintering of alumina ceramics, the added magnesium oxide tends to accumulate at the alumina grain boundaries, causing alumina grain growth and the formation of a large amount of unevenly distributed glassy phase. This reduces the average grain boundary strength of the alumina ceramic. The low thermal conductivity of the glassy phase also reduces the thermal conductivity of the alumina ceramic, which is detrimental to the performance of the anti-twisting head.

[0073] This invention introduces magnesium oxide in the form of magnesium nitrate. By immersing the pre-fired blank in a magnesium-containing solution, magnesium is uniformly coated on the surface of alumina grains in the form of magnesium nitrate. The amount of magnesium doping can be adjusted by changing the concentration of magnesium nitrate and the immersion time. In other words, the amount of magnesium oxide doped is controlled by controlling the concentration of magnesium nitrate solution. In this way, magnesium nitrate coats the alumina grains in a thin layer, which promotes sintering during sintering and prevents the formation of excess glass phase due to the accumulation of magnesium oxide at the grain boundaries.

[0074] (5) Two-step sintering process for ceramic anti-twisting heads: The purified and dried anti-twisting head blank is placed in a vacuum furnace, heated first and then cooled, held at that temperature, and then cooled to room temperature before the furnace is opened to obtain an alumina ceramic anti-twisting head blank. The specific operation method is as follows: The purified and dried anti-twisting head blank is placed in a vacuum furnace, heated to 1550-1600℃ at a heating rate of 5-15℃ / min, then cooled to 1450-1500℃ at a heating rate of 3-10℃ / min, held at that temperature for 5-12 hours, and then cooled to room temperature before the furnace is opened to obtain an alumina ceramic anti-twisting head blank. Under a vacuum atmosphere, oxygen ions diffuse, increasing the diffusion rate of pores in the ceramic blank and reducing the porosity.

[0075] The conventional sintering process for alumina ceramics involves heating in air from room temperature at a rate of 10-20°C / hour, holding at certain temperatures (900, 1200, 1450) for 30-60 minutes, and finally heating to the maximum temperature and holding for 1-2 hours to complete the sintering process. However, using conventional sintering processes makes it difficult to sinter alumina ceramics with low porosity, fine grains (1-2 μm), high strength, and high wear resistance.

[0076] Through exploration, the inventors discovered that densification begins within a temperature range of 20-50°C below the maximum sintering temperature, while grain boundary movement is not yet activated. The temperature at which densification begins is set as T1. Once T1 is reached, the temperature is lowered at a certain rate to T2, which is 100-150°C below the maximum sintering temperature. This temperature is then maintained at T2 for a relatively long period, 5-12 hours. Sintering in this temperature range eliminates residual porosity without the final stage of grain growth. This sintering process yields alumina ceramics with high density and fine grains.

[0077] (6) Machining and polishing of ceramic anti-twisting head: The sintered anti-twisting head blank is ground in length and outer diameter using a diamond grinding wheel, and then the working part of the anti-twisting head surface is polished using diamond polishing paste to obtain a high-purity, high-thermal-conductivity fine-grained alumina ceramic anti-twisting head finished product.

[0078] Example 1

[0079] 1. React excess high-purity metallic aluminum with 20% dilute hydrochloric acid. After filtration, purify the obtained aluminum chloride using ion exchange resin and activated carbon to remove impurities, and obtain an aluminum chloride solution.

[0080] 2. The obtained aluminum chloride solution was repeatedly distilled under reduced pressure to obtain high-purity aluminum chloride powder.

[0081] 3. The obtained high-purity aluminum chloride powder is heated to 300℃ to form aluminum chloride vapor. The aluminum chloride vapor is then passed into a combustion tower lined with 99% alumina ceramic, and hydrogen and oxygen are introduced for combustion. Aluminum hydroxide particles are obtained by gas-phase precipitation, wherein the molar ratio of aluminum chloride vapor: hydrogen: oxygen = 5:3:1.

[0082] 4. Add the obtained aluminum hydroxide particles to a polytetrafluoroethylene-lined reactor, add deionized water, stir to form aluminum hydroxide sol, then heat to 100 degrees Celsius and pressurize to 0.8 MPa to precipitate aluminum oxide crystals.

[0083] 5. After pressure filtration, the alumina is calcined at low temperature and crushed to obtain high-purity, ultrafine alumina powder with few hard agglomerates, which is 99.99% pure.

[0084] 6. Weigh 10 kg of the high-purity ceramic powder obtained from spray drying and add it to a mixer. Then add the binder and mix for 120 minutes at a rotor speed of 50 r / min. The binder composition is as follows:

[0085] PVB resin LLDPE EVA Behenic acid Monoglyceride Content wt% Deionized water CE64 dispersant 10% HCL + 10% HNO3 solution 20 10 40 10 10 2 5 3

[0086] 7. After the mixed feedstock cools, it is broken into small pieces and placed into an injection molding machine. A piercing needle mold is then attached, and injection molding is performed to obtain a ceramic anti-twist head green body. The injection temperature is 165℃, the injection pressure is 80MPa, and the injection speed is 100mm / s. Optimization of the injection formulation increases the feedstock's flowability and shape retention, ensuring good mold filling performance. Microscopic observation reveals a smooth surface on the anti-twist head green body, free of pores, watermarks, and shrinkage cavities caused by thermal shrinkage.

[0087] 8. Place the formed ceramic anti-twist head green body into a medium-temperature degreasing furnace to remove the organic binder and complete the pre-sintering, giving the green body a certain strength for subsequent purification treatment. The heating curve is as follows: room temperature - 100℃, 2℃ / min; 100-250℃, 0.5℃ / min; 250-450℃, 1℃ / min; 450-750℃, 3℃ / min; hold at 750℃ for 1 hour.

[0088] 9. Place the pre-fired twist-resistant head blank into a clean plastic sieve, then place the sieve into a circulating water tank. Add purifying agent 1 to the tank, allowing it to circulate through the sieve. The purpose of the circulating water tank is to ensure that the purifying agent 1, after dissolving impurities in the blank, quickly carries them out of the pre-formed blank. The purification process takes 5 hours. Purifying agent 1 consists of deionized water, CE64 dispersant, and 20% analytical grade HCl solution. The composition ratio is as follows:

[0089] Ratio Anhydrous ethanol D-305 dispersant 25% NH3.H2O solution 60％ 2％ 38％

[0090] 10. Place the purified blank into a flowing deionized water tank to further remove metal ion impurities and the infiltrated purifying agent 1 for 2 hours.

[0091] 11. Remove the cleaned blank from the plastic sieve and place it in a clean enamel tray. First, air dry it at room temperature for 15 hours, then put it in an oven and dry it at 50°C for 3 hours, and then at 120°C for 5 hours.

[0092] 12. Place the thoroughly dried preform into a muffle furnace and continue pre-firing. The heating curve is as follows: room temperature - 100℃, 2℃ / min, 100-250℃, 0.5℃ / min, 250-450℃, 1℃ / min, 450-750℃, 3℃ / min, and hold at 1050℃ for 1 hour.

[0093] 13. Place the pre-fired twist-resistant head blank into a clean plastic sieve, then place the sieve into a circulating water tank. Add purifying agent 2 to the water tank. Purifying agent 2 circulates through the plastic sieve. The purpose of using a circulating water tank is to allow purifying agent 2 to dissolve impurities in the blank and quickly carry them out of the pre-formed blank. The purification treatment time is 10 hours. Purifying agent 2 consists of anhydrous ethanol, D-305 dispersant, and 25% NH3·H2O solution. Its composition ratio is as follows:

[0094] Ratio Paraffin wax Food wax Acrylic resin 70％ 0.5％ 29.5％

[0095] 14. Place the purified blank into a flowing deionized water tank to further remove residual metal ion impurities and the infiltrated purification agent 2 during the second purification process for 2 hours.

[0096] 15. Remove the purified green body from the plastic sieve and place it in a clean enamel dish. First, air dry it at room temperature for 15 hours, then put it in an oven and dry it at 80°C for 1 hour, and then at 120°C for 2 hours.

[0097] 16. Dissolve magnesium nitrate in deionized water to form a solution with a concentration of 0.05 mol / L. Then immerse the pre-calcined alumina billet in the magnesium nitrate solution for 3 hours. After removing the billet, let it air dry naturally, and then place it in an oven and bake at 140℃ for 2 hours.

[0098] 17. Place the purified and dried anti-twisting head blank into a vacuum furnace, heat it to 1550℃ at a rate of 5℃ / min, then cool it to 1450℃ at a rate of 3℃ / min and hold it at that temperature for 12 hours. After cooling to room temperature in the furnace, the furnace is opened to obtain an alumina ceramic anti-twisting head blank.

[0099] 18. Use a diamond grinding wheel to grind the length and outer diameter of the sintered anti-twisting head blank, and then use diamond polishing paste to polish the working parts of the anti-twisting head surface to obtain the finished high-purity, high-thermal-conductivity fine-grained alumina ceramic anti-twisting head.

[0100] Example 2

[0101] 1. React excess high-purity metallic aluminum with 20% dilute hydrochloric acid. After filtration, purify the obtained aluminum chloride using ion exchange resin and activated carbon to remove impurities, and obtain an aluminum chloride solution.

[0102] 2. The obtained aluminum chloride solution was repeatedly distilled under reduced pressure to obtain high-purity aluminum chloride powder.

[0103] 3. The obtained high-purity aluminum chloride powder is heated to 300℃ to form aluminum chloride vapor. The aluminum chloride vapor is then passed into a combustion tower lined with 99% alumina ceramic, and hydrogen and oxygen are introduced for combustion. Aluminum hydroxide particles are obtained by gas-phase precipitation, wherein the molar ratio of aluminum chloride vapor: hydrogen: oxygen = 2:5:3.

[0104] 4. Add the obtained aluminum hydroxide particles to a polytetrafluoroethylene-lined reactor, add deionized water, stir to form aluminum hydroxide sol, and then heat to 95 degrees Celsius and pressurize to 2 MPa to precipitate aluminum oxide crystals.

[0105] 5. After pressure filtration, the alumina is calcined at low temperature and crushed to obtain high-purity, ultrafine alumina powder with few hard agglomerates, which is 99.99% pure.

[0106] 6. Weigh 10 kg of the high-purity ceramic powder obtained from spray drying and add it to a mixer. Then add the binder and mix for 180 minutes at a rotor speed of 70 r / min. The binder composition is as follows:

[0107] PVB resin LLDPE EVA Behenic acid Monoglyceride Content wt% Deionized water CE64 dispersant 10% HCL + 10% HNO3 solution 10 10 50 10 15 2 2 1

[0108] 7. After the mixed feedstock cools, it is broken into small pieces and placed into an injection molding machine. A piercing needle mold is then attached, and injection molding is performed to obtain a ceramic anti-twist head green body. The injection temperature is 190℃, the injection pressure is 50MPa, and the injection speed is 50mm / s. Optimization of the injection formulation increases the feedstock's flowability and shape retention, ensuring good mold filling performance. Microscopic observation reveals a smooth surface on the anti-twist head green body, free of pores, watermarks, and shrinkage cavities caused by thermal shrinkage.

[0109] 8. Place the formed ceramic anti-twist head green body into a medium-temperature degreasing furnace to remove the organic binder and complete the pre-sintering, giving the green body a certain strength for subsequent purification treatment. The heating curve is as follows: room temperature - 100℃, 5℃ / min; 100-250℃, 2℃ / min; 250-450℃, 2℃ / min; 450-750℃, 5℃ / min; hold at 750℃ for 3 hours.

[0110] 9. Place the pre-fired twist-resistant head blank into a clean plastic sieve, then place the sieve into a circulating water tank. Add purification agent 1 to the tank, allowing it to circulate through the sieve. The purpose of the circulating water tank is to ensure that the purification agent 1, after dissolving impurities in the blank, quickly carries them out of the pre-formed blank. The purification process takes 10 hours. Purification agent 1 consists of deionized water, CE64 dispersant, and 20% analytical grade HCl solution. The composition ratio is as follows:

[0111] Ratio Anhydrous ethanol D-305 dispersant 25% NH3.H2O solution 69.5％ 0.5％ 30％

[0112] 10. Place the purified blank into a flowing deionized water tank to further remove metal ion impurities and the infiltrated purifying agent 1 for 6 hours.

[0113] 11. Remove the cleaned blank from the plastic sieve and place it in a clean enamel tray. First, air dry it at room temperature for 30 hours, then put it in an oven and dry it at 80°C for 1 hour, and then at 120°C for 2 hours.

[0114] 12. Place the thoroughly dried preform into a muffle furnace and continue pre-firing. The heating curve is as follows: room temperature - 100℃, 5℃ / min, 100-250℃, 2℃ / min, 250-450℃, 2℃ / min, 450-750℃, 5℃ / min, and hold at 1050℃ for 3 hours.

[0115] 13. Place the pre-fired twist-resistant head blank into a clean plastic sieve, then place the sieve into a circulating water tank. Add purifying agent 2 to the water tank. Purifying agent 2 circulates through the plastic sieve. The purpose of using a circulating water tank is to allow purifying agent 2 to dissolve impurities in the blank and quickly carry them out of the pre-formed blank. The purification treatment time is 5 hours. Purifying agent 2 consists of anhydrous ethanol, D-305 dispersant, and 25% NH3·H2O solution. Its composition ratio is as follows:

[0116] Ratio Paraffin wax Food wax Acrylic resin 80％ 1％ 19％

[0117] 14. Place the purified blank into a flowing deionized water tank to further remove residual metal ion impurities and the infiltrated purification agent 2 from the secondary purification process for 6 hours.

[0118] 15. Remove the purified green body from the plastic sieve and place it in a clean enamel dish. First, air dry it at room temperature for 30 hours, then put it in an oven and dry it at 60°C for 2 hours, and then at 120°C for 4 hours.

[0119] 16. Dissolve magnesium nitrate in deionized water to form a solution with a concentration of 0.2 mol / L. Then immerse the pre-calcined alumina blank in the magnesium nitrate solution for 6 hours. After removing the blank, let it air dry naturally, and then place it in an oven and bake at 110℃ for 5 hours.

[0120] 17. Place the purified and dried anti-twisting head blank into a vacuum furnace, heat it to 1600℃ at a heating rate of 15℃ / min, then cool it to 1500℃ at a heating rate of 10℃ / min and hold it at that temperature for 5 hours. Then cool it to room temperature with the furnace and open the furnace to obtain an alumina ceramic anti-twisting head blank.

[0121] 18. Use a diamond grinding wheel to grind the length and outer diameter of the sintered anti-twisting head blank, and then use diamond polishing paste to polish the working parts of the anti-twisting head surface to obtain the finished high-purity, high-thermal-conductivity fine-grained alumina ceramic anti-twisting head.

[0122] Example 3

[0123] 1. React excess high-purity metallic aluminum with 20% dilute hydrochloric acid. After filtration, purify the obtained aluminum chloride using ion exchange resin and activated carbon to remove impurities, and obtain an aluminum chloride solution.

[0124] 2. The obtained aluminum chloride solution was repeatedly distilled under reduced pressure to obtain high-purity aluminum chloride powder.

[0125] 3. The obtained high-purity aluminum chloride powder is heated to 300℃ to form aluminum chloride vapor. The aluminum chloride vapor is then passed into a combustion tower lined with 99% alumina ceramic, and hydrogen and oxygen are introduced for combustion. Aluminum hydroxide particles are obtained by gas-phase precipitation, wherein the molar ratio of aluminum chloride vapor: hydrogen: oxygen = 3:4:2.

[0126] 4. Add the obtained aluminum hydroxide particles to a polytetrafluoroethylene-lined reactor, add deionized water, stir to form aluminum hydroxide sol, and then heat to 98 degrees Celsius and pressurize to 1.2 MPa to precipitate aluminum oxide grains.

[0127] 5. After pressure filtration, the alumina is calcined at low temperature and crushed to obtain high-purity, ultrafine alumina powder with few hard agglomerates, which is 99.99% pure.

[0128] 6. Weigh 10 kg of the high-purity ceramic powder obtained from spray drying and add it to a mixer. Then add the binder and mix for 150 minutes at a rotor speed of 65 r / min. The binder composition is as follows:

[0129] PVB resin LLDPE EVA Behenic acid Monoglyceride Content wt% Deionized water CE64 dispersant 10% HCL + 10% HNO3 solution 12 6 45 14 11 2 5 5

[0130] 7. After the mixed feedstock cools, it is broken into small pieces and placed into an injection molding machine. A coffee machine piercing needle mold is then attached, and injection molding is performed to obtain a ceramic anti-twist head green body. The injection temperature is 175℃, the injection pressure is 60MPa, and the injection speed is 72mm / s. By optimizing the injection formulation, the feedstock flowability and shape retention are increased, ensuring good mold filling performance. Microscopic observation shows that the surface of the anti-twist head green body is smooth, without pores, watermarks, or shrinkage cavities caused by thermal shrinkage.

[0131] 8. Place the formed ceramic anti-twist head green body into a medium-temperature degreasing furnace to remove the organic binder and complete the pre-sintering, giving the green body a certain strength for subsequent purification treatment. The heating curve is as follows: room temperature - 100℃, 3℃ / min; 100-250℃, 1.5℃ / min; 250-450℃, 1.5℃ / min; 450-750℃, 4℃ / min; and hold at 750℃ for 2 hours.

[0132] 9. Place the pre-fired twist-resistant head blank into a clean plastic sieve, then place the sieve into a circulating water tank. Add purification agent 1 to the tank, allowing it to circulate through the sieve. The purpose of the circulating water tank is to ensure that the purification agent 1, after dissolving impurities in the blank, quickly carries them out of the pre-formed blank. The purification process takes 7 hours. Purification agent 1 consists of deionized water, CE64 dispersant, and 20% analytical grade HCl solution. Its composition ratio is as follows:

[0133] Ratio Anhydrous ethanol D-305 dispersant 25% NH3.H2O solution 65％ 1％ 34％

[0134] 10. Place the purified blank into a flowing deionized water tank to further remove metal ion impurities and the infiltrated purifying agent 1 for 4 hours.

[0135] 11. Remove the cleaned blank from the plastic sieve and place it in a clean enamel tray. First, air dry it at room temperature for 24 hours, then put it in an oven and dry it at 65°C for 2 hours, and then at 120°C for 4 hours.

[0136] 12. Place the thoroughly dried preform into a muffle furnace and continue pre-firing. The heating curve is as follows: room temperature - 100℃, 3.5℃ / min; 100-250℃, 1℃ / min; 250-450℃, 1.5℃ / min; 450-750℃, 3.5℃ / min; and hold at 1050℃ for 2.5 hours.

[0137] 13. Place the pre-fired twist-resistant head blank into a clean plastic sieve, then place the sieve into a circulating water tank. Add purifying agent 2 to the water tank. Purifying agent 2 circulates through the plastic sieve. The purpose of using a circulating water tank is to allow purifying agent 2 to dissolve impurities in the blank and quickly carry them out of the pre-formed blank. The purification treatment time is 8 hours. Purifying agent 2 consists of anhydrous ethanol, D-305 dispersant, and 25% NH3·H2O solution. Its composition ratio is as follows:

[0138] Ratio Figure 1 Figure 2 Figure 3 75％ 1.5％ 23.5％

[0139] 14. Place the purified blank into a flowing deionized water tank to further remove residual metal ion impurities and the infiltrated purification agent 2 from the secondary purification process for 4.5 hours.

[0140] 15. Remove the purified green body from the plastic sieve and place it in a clean enamel dish. First, air dry it at room temperature for 24 hours, then put it in an oven and dry it at 50°C for 3 hours, and then at 120°C for 4.5 hours.

[0141] 16. Dissolve magnesium nitrate in deionized water to form a solution with a concentration of 0.1 mol / L. Then immerse the pre-calcined alumina billet in the magnesium nitrate solution for 4 hours. After removing the billet, let it air dry naturally, and then place it in an oven and bake at 125°C for 3 hours.

[0142] 17. Place the purified and dried anti-twisting head blank into a vacuum furnace, heat it to 1580°C at a heating rate of 7°C / min, then cool it down to 1480°C at a rate of 5°C / min and hold it at that temperature for 10 hours. Then cool it to room temperature with the furnace and open the furnace to obtain an alumina ceramic anti-twisting head blank.

[0143] 18. Use a diamond grinding wheel to grind the length and outer diameter of the sintered anti-twisting head blank, and then use diamond polishing paste to polish the working parts of the anti-twisting head surface to obtain the finished high-purity, high-thermal-conductivity fine-grained alumina ceramic anti-twisting head.

[0144] The properties of the high-purity, high-thermal-conductivity, fine-grained alumina ceramic anti-twisting heads prepared through the above three embodiments are shown in the table below. Meanwhile, the scanning electron microscope (SEM) images of the high-purity, high-thermal-conductivity, fine-grained alumina ceramic anti-twisting heads prepared through the above three embodiments are shown below. Item , Hardness (Hv) , Grain size As shown.

[0145] Density (g / cm3) Example 1 3 um Example 2 4 um Example 3 1780 2 um 98.7％ 3.952 Example 4 1820 2 um 98.65％ 3.945 Example 5 1865 2 um Example 6 2 um Example 7 2 um Example 8 2 um Example 9 2 um Example 10 2 um Example 11 2 um Example 12 2 um Example 13 2 um Example 14 2 um Example 15 2 um Example 16 2 um Example 17 2 um Example 18 2 um Example 19 2 um Example 20 2 um Example 21 2 um Example 22 2 um Example 23 2 um Example 24 2 um Example 25 2 um Example 26 2 um Example 27 2 um Example 28 2 um Example 29 2 um Example 30 2 um Example 31 2 um Example 32 2 um Example 33 2 um Example 34 2 um Example 35 2 um Example 36 2 um Example 37 2 um Example 38 2 um Example 39 2 um Example 40 2 um Example 41 2 um Example 42 2 um Example 43 2 um Example 44 2 um Example 45 2 um Example 46 2 um Example 47 2 um Example 48 2 um Example 49 2 um Example 50 2 um Example 51 2 um Example 52 2 um Example 53 2 um Example 54 2 um Example 55 2 um Example 56 2 um Example 57 2 um Example 58 2 um Example 59 2 um Example 60 2 um Example 61 2 um Example 62 2 um Example 63 2 um Example 64 2 um Example 65 2 um Example 66 2 um Example 67 2 um Example 68 2 um Example 69 2 um Example 70 2 um Example 71 2 um Example 72 2 um Example 99.1％ 3.967

Claims

1. A method for preparing a ceramic twist-blocking head for an air-jet spinning machine, characterized in that, Specifically, the steps include the following: (1) Preparation of high-purity alumina powder: High-purity metallic aluminum is reacted with dilute hydrochloric acid, and the obtained aluminum chloride is purified to remove impurities after filtration to obtain aluminum chloride solution. High-purity aluminum chloride powder is obtained by multiple vacuum distillations. The aluminum chloride vapor is heated and passed into an alumina ceramic combustion tower, and then hydrogen and oxygen are introduced for combustion to obtain aluminum hydroxide particles. The particles are added to a reaction vessel lined with polytetrafluoroethylene, deionized water is added, and the mixture is stirred to form aluminum hydroxide sol. The alumina crystals are precipitated by heating, filtered, calcined at low temperature, and crushed to obtain high-purity alumina powder. (2) Preparation of high-purity alumina ceramic anti-twisting head green body: The high-purity alumina powder obtained by spray drying is added to the internal mixer, then the binder is added for mixing, cooling, and crushing into small pieces. The green body is then placed in the injection molding machine, fitted with a coffee machine puncture needle mold, and injection molded to obtain the ceramic anti-twisting head green body. The molded ceramic anti-twisting head green body is then placed in a medium-temperature degreasing furnace to remove the organic binder and complete the pre-sintering. (3) Purification treatment of anti-twist head preform: Place the pre-fired anti-twist head preform into a clean plastic screen, then put the screen into a circulating water tank, add purifying agent 1 into the water tank, and circulate purifying agent 1 through the plastic screen. Place the preform after purification treatment into a flowing deionized water tank. Take the preform after the first purification from the plastic screen and place it into a clean enamel tray. First, air dry at room temperature, then put it into an oven. Place the thoroughly dried preform into a muffle furnace for further pre-firing. Place the pre-fired anti-twist head preform into a clean plastic screen, then put the screen into a circulating water tank, add purifying agent 2 into the water tank, and circulate purifying agent 2 through the plastic screen. Place the preform after purification treatment into a flowing deionized water tank. Take the preform after the second purification from the plastic screen and place it into a clean enamel tray. First, air dry at room temperature, then put it into an oven. (4) Doping treatment of anti-twisting head preform: dissolve magnesium nitrate in deionized water to form a solution, then immerse the pre-fired alumina blank in the magnesium nitrate solution, take out the blank and let it air dry naturally, and then place it in an oven; (5) Two-step sintering process of ceramic anti-twisting head: The purified and dried anti-twisting head blank is placed in a vacuum furnace, heated first and then cooled down, and kept at the temperature before being cooled to room temperature and then the furnace is opened to obtain alumina ceramic anti-twisting head blank. (6) Machining and polishing of ceramic anti-twisting head: The sintered anti-twisting head blank is ground in length and outer diameter using a diamond grinding wheel, and then the working part of the anti-twisting head surface is polished using diamond polishing paste to obtain a high-purity, high-thermal-conductivity fine-grained alumina ceramic anti-twisting head finished product.

2. The method for preparing a ceramic twist-resistant head for an air-jet spinning machine according to claim 1, characterized in that, In step (1), the specific operation method is as follows: (11) React excess high-purity metallic aluminum with 20% dilute hydrochloric acid, filter, and then purify the obtained aluminum chloride by using ion exchange resin and activated carbon to remove impurities, and obtain aluminum chloride solution. (12) The obtained aluminum chloride solution was repeatedly distilled under reduced pressure to obtain high-purity aluminum chloride powder; (13) The obtained high-purity aluminum chloride powder is heated to 300°C to form aluminum chloride vapor. The aluminum chloride vapor is passed into a combustion tower lined with 99% alumina ceramic, and then hydrogen and oxygen are passed in for combustion. Aluminum hydroxide particles are obtained by gas phase precipitation. (14) Add the obtained aluminum hydroxide particles to a reaction vessel lined with polytetrafluoroethylene, add deionized water, stir to form aluminum hydroxide sol, and then heat to 95-100 degrees Celsius and pressure 0.8-2 MPa to precipitate aluminum oxide grains. (15) After pressure filtration, the alumina is calcined at low temperature and crushed to obtain 99.99% high-purity alumina powder with high purity, ultrafine texture and few hard agglomerates.

3. The method for preparing a ceramic twist-resistant head for an air-jet spinning machine according to claim 2, characterized in that, In step (13), the molar ratio of aluminum chloride vapor: hydrogen: oxygen is 5:3:1-2:5:

3.

4. The method for preparing a ceramic twist-blocking head for an air-jet spinning machine according to claim 1, characterized in that, In step (2), the specific operation method is as follows: (21) Weigh 10 kg of the high-purity alumina ceramic powder obtained by spray drying and add it to the internal mixer. Then add the binder and mix for 120-180 min. The rotor speed of the mixer is 50-70 r / min. (22) After the well-mixed feed is cooled, it is broken into small pieces, put into the injection molding machine, and the coffee machine piercing needle mold is installed. The injection molding is performed to obtain the ceramic anti-twist head green body. The injection temperature is 165-190℃, the injection pressure is 50-80MPa, and the injection speed is 50-100mm / s. (23) Place the formed ceramic anti-twist head green body into a medium-temperature degreasing furnace to remove the organic binder and complete the pre-sintering, so that the green body has a certain strength for subsequent purification treatment. The heating curve is as follows: room temperature - 100℃, 2-5℃ / min; 100-250℃, 0.5-2℃ / min; 250-450℃, 1-2℃ / min; 450-750℃, 3-5℃ / min; 750℃ for 1-3 hours.

5. A method for preparing a ceramic twist-resistant head for an air-jet spinning machine according to claim 1 or 4, characterized in that, In step (2), the adhesive is composed of the following components by mass percentage: paraffin wax 10-20 wt%, food wax 5-10 wt%, acrylic resin 40-50 wt%, PVB resin 10-20 wt%, LLDPE 10-20 wt%, EVA 2-5 wt%, behenic acid 1-5 wt%, and monoglyceride 1-5 wt%.

6. The method for preparing a ceramic twist-blocking head for an air-jet spinning machine according to claim 1, characterized in that, In step (3), the specific operation method is as follows: (31) Place the pre-fired anti-twist head blank into a clean plastic screen, then put the screen into a circulating water tank, put purification agent 1 into the water tank, and circulate the purification agent 1 through the plastic screen for 5-10 hours. (32) Place the purified blank into a flowing deionized water tank to further remove metal ion impurities and the penetrating purification agent 1 for 2-6 hours. (33) Take the purified green body out of the plastic screen and put it into a clean enamel plate. First, air dry it at room temperature for 15-30 hours, and then put it into an oven. First, dry it at 50-80℃ for 1-3 hours, and then dry it at 120℃ for 2-5 hours. (34) Place the thoroughly dried preform into a muffle furnace and continue pre-firing. The heating curve is as follows: room temperature - 100℃, 2-5℃ / min; 100-250℃, 0.5-2℃ / min; 250-450℃, 1-2℃ / min; 450-750℃, 3-5℃ / min; 1050℃ for 1-3 hours. (35) Place the pre-fired twist-resistant head blank into a clean plastic screen, then put the screen into a circulating water tank, add purifying agent 2 into the water tank, and circulate purifying agent 2 through the plastic screen for 5-10 hours. (36) Place the purified blank into a flowing deionized water tank to further remove the metal ion impurities remaining during the secondary purification and the purified agent 2 that has been introduced, for a time of 2-6 hours. (37) Take the purified green body out of the plastic screen and put it into a clean enamel plate. First, air dry it at room temperature for 15-30 hours, and then put it into an oven. First, dry it at 50-80℃ for 1-3 hours, and then dry it at 120℃ for 2-5 hours.

7. A method for preparing a ceramic twist-resistant head for an air-jet spinning machine according to claim 1 or 6, characterized in that, In step (3), the purifying agent 1 is composed of deionized water, CE64 dispersant, and 20% analytical grade HCl solution, wherein the 20% analytical grade HCl solution refers to a 10% HCl + 10% HNO3 solution. The composition ratio of the purifying agent 1 is: 60%-70% deionized water, 0.5-2% CE64 dispersant, and 30%-40% 20% analytical grade HCl solution.

8. A method for preparing a ceramic twist-resistant head for an air-jet spinning machine according to claim 1 or 6, characterized in that, In step (3), the purifying agent 2 is composed of anhydrous ethanol, D-305 dispersant, and 25% NH3.H2O solution. The composition ratio of the purifying agent 2 is: 70%-85% anhydrous ethanol, 0.5-2% D-305 dispersant, and 18%-40% 25% NH3.H2O solution.

9. The method for preparing a ceramic twist-resistant head for an air-jet spinning machine according to claim 1, characterized in that, In step (4), the specific operation method is as follows: dissolve magnesium nitrate in deionized water to form a solution with a concentration of 0.05-0.2 mol / L, then immerse the pre-fired alumina blank in the magnesium nitrate solution for 3-6 hours, take out the blank and let it air dry naturally, then place it in an oven and bake at 110-140℃ for 2-5 hours.

10. The method for preparing a ceramic twist-blocking head for an air-jet spinning machine according to claim 1, characterized in that, In step (5), the specific operation method is as follows: the purified and dried anti-twisting head blank is placed in a vacuum furnace and heated to 1550-1600℃ at a heating rate of 5-15℃ / min, and then cooled to 1450-1500℃ at a heating rate of 3-10℃ / min, and kept at the temperature for 5-12 hours. Then, it is cooled to room temperature with the furnace and the furnace is opened to obtain the alumina ceramic anti-twisting head blank.

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