Crust-free ceramic slurry and preparation method thereof

Abstract

The invention discloses a crust-free ceramic slurry and a preparation method thereof, and relates to the technical field of ceramic slurry, in the process of preparing the ceramic slurry, crust can be formed on the surface layer of the slurry, the crust is generally distributed in the vertical direction of a stirring slurry, if stirring is continued, the crust can fall into the slurry, and the defects of protrusions, lines and the like occur subsequently; polyethylene glycol diacrylate molecular chains are adsorbed on the surfaces of alumina particles to form steric hindrance layers, the particles are dispersed under the action of electrostatic repulsion and steric hindrance, the surfaces of the particles are fully wetted by water, and the overall flowability of the slurry is improved; the montmorillonite and the carboxymethyl cellulose are grafted to form a polymer with more pores, larger pore diameters and uniform distribution, and the structure can provide more space water absorption expansion for the slurry and firmly bind water molecules under the action of hydrogen bonds, so that the water retention capacity of the ceramic slurry is improved, and the generation of surface crust of the slurry is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic slurries, in particular to a non-skinning ceramic slurry and a preparation method thereof. Background Art

[0002] When degassing ceramic slurry, if a large number of bubbles are generated during the stirring process and cannot be discharged, a large number of bubbles will remain in the slurry, and these residual bubbles will affect subsequent processes, such as causing defects such as pits, cracks, and pinholes; if the environment is not suitable, a crust will form on the surface of the slurry. This crust is usually distributed in the vertical direction of the stirring paddle. If stirring continues, the crust will fall into the interior of the slurry, resulting in subsequent defects such as protrusions and lines.

[0003] Therefore, in order to improve the problem of slurry skinning, the present invention provides a skin-free ceramic slurry and a preparation method thereof. Summary of the Invention

[0004] The object of the present invention is to provide a skin-free ceramic slurry and a preparation method thereof, so as to solve the problems raised in the prior art.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A non-skinning ceramic slurry and a preparation method thereof, comprising the following steps:

[0007] Step 1: Add alumina ceramic slurry into a diaphragm pump and discharge compressed air at a pressure of 0.1-0.5 MPa; filter; heat the degassing tank at 32-℃ water circulation for 25-30 minutes, and discharge the alumina ceramic slurry into the degassing tank at a flow rate of 6-15 L / min;

[0008] Step 2: Maintain the degassing tank at a constant temperature of 29-45°C for the first degassing; adjust the vacuum degree of the degassing tank for the second degassing; adjust the degassing speed and the vacuum degree of the degassing tank for the third degassing to obtain a ceramic slurry without skinning.

[0009] More optimally, in step 1, the filtration is performed using two filters connected in series, one filter is 200 mesh and the second filter is 500 mesh.

[0010] More optimally, in step 1, the discharging parameters are: discharging pressure of 0.1-0.55 MPa, discharging viscosity of 1000-5000 cp, and discharging solid content of 50-75%.

[0011] More optimized, in step 2, for the first deaeration, the deaeration speed is 30-90r / min, the vacuum degree of the deaeration tank is -50kpa~(-70kpa), the water circulation temperature is 30-45°C, and the time is 20-60min; for the second deaeration, the vacuum degree of the deaeration tank is -85kpa~(-97kpa), the water circulation temperature is 30-45°C, and the time is 22-24h, so that the slurry casting viscosity is 6000-12000cp and the casting solid content is 58-66%; for the third deaeration, the deaeration speed is 5-32r / min, the vacuum degree of the deaeration tank is -70kpa~(-85KPa), the water circulation temperature is 30-40°C, and the time is 2-12h.

[0012] More preferably, in step 1, the preparation method of alumina ceramic slurry comprises the following steps:

[0013] Step A: 20 g of carboxylated alumina was added to 100 mL of ethanol, ultrasonically dispersed, ground, and dried to obtain ceramic powder. 10 g of the ceramic powder was added to 7 g of glycerol, mixed evenly, and ultrasonically dispersed for 4 to 6 hours. 0.5 g of glycerol and 0.3 g of carrageenan were then added and mixed to pre-dissolve the colloid. The stirring time was 10 to 12 hours, the heating temperature was 80 to 100° C., and the stirring rate was 500 r / min to obtain a colloid.

[0014] Step B: Add 10 g of colloid, 3 g of polyethylene glycol diacrylate and 2 g of potassium persulfate to 30 mL of the mixed solution, stir evenly and heat at 200-220° C. for 3-5 hours to obtain substance A;

[0015] Step C: Take half of the substance A and add polyethylene glycol, ball mill, and ball mill for 6 to 8 hours at a speed of 500 rpm, rotating forward for 10 to 12 minutes, reverse for 9 to 11 minutes, and rest for 3 to 5 minutes. Add the remaining substance A, and ball mill for 12 to 14 hours at a speed of 500 rpm, rotating forward for 10 to 12 minutes, reverse for 9 to 11 minutes, and rest for 3 to 5 minutes. Adjust the speed to 5 to 20 r / min, and ball mill for 1 to 3 hours to obtain an alumina ceramic slurry.

[0016] A more optimized method for preparing the mixed solution is: take 3 g of carboxymethyl cellulose and dissolve it in 100 mL of deionized water, and stir it magnetically for 30 to 40 minutes to form a carboxymethyl cellulose solution; add 1 g of montmorillonite to 30 mL of deionized water to prepare a montmorillonite suspension; add 30 mL of the montmorillonite suspension to 50 mL of the carboxymethyl cellulose solution, react at 80 to 100°C for 2 to 4 hours, and add acetic acid dropwise to pH = 7 to obtain a mixed solution.

[0017] A more optimized preparation method of carboxylated alumina is as follows: 2.5 g of silane coupling agent KH550 is added to 1.3 g of succinic anhydride and 30 mL of dimethylformamide, mixed and stirred for 5 to 7 hours to obtain a modified liquid; 8 g of alumina powder is added to 110 mL of dimethylformamide, ultrasonically dispersed for 2 to 4 hours, 5 mL of the modified liquid and 6 mL of deionized water are added, stirred for 10 to 12 hours, filtered, washed, and dried at 100 to 120°C to obtain carboxylated alumina.

[0018] A more optimized preparation method of carboxymethyl cellulose is as follows: add 25 g of wood cellulose to 100 mL of sodium hydroxide solution, ultrasonically disperse for 12 to 14 hours, filter, add 100 mL of anhydrous ethanol, stir evenly, add 12 g of chloroacetic acid, react at 70 to 90 ° C for 6 to 8 hours, filter, add 50 mL of deionized water, add acetic acid dropwise to pH = 7, dry and grind to obtain carboxymethyl cellulose.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The ball mill degassing designed in this invention reduces frictional heat generation through low rotation speed, inhibits evaporation of volatile components, and reduces the formation of crusting; the low rotation speed slows the material flow rate, and the gas has more time to escape through the gaps between the ceramic slurry, and the slow movement inhibits trapped bubbles.

[0021] 2. The filter screen combination designed by the present invention, the 200-mesh and 500-mesh filter screen combination, can filter out the ceramic slurry crust and slurry particles during the ball milling process, and squeeze out the large bubbles in the ceramic slurry; the tank body is heated to avoid temperature difference contact with the crust, increase the discharge flow rate control, and avoid the filter screen from being stretched and damaged, which will deteriorate the filtering effect.

[0022] 3. The degassing process designed in the present invention solves the problem of skinning on the slurry surface; compressed air prevents air from blowing directly onto the ceramic slurry surface, improving skinning caused by temperature changes and airflow disturbances.

[0023] 4. The present invention improves the difference in solid content of the ceramic slurry in the tank body, and the solid content of the ceramic slurry is 1%.

[0024] 5. The sliding surface of alumina particles is more charged, and the particle repulsion is larger. The polyethylene glycol diacrylate molecular chain is adsorbed on the surface of alumina particles, forming a steric hindrance layer, which hinders the aggregation of particles. The electrostatic repulsion and steric hindrance cause the particles to disperse, and the particle surface is fully wetted by water, which improves the overall fluidity of the slurry and reduces the overall viscosity.

[0025] 6. Carboxymethyl cellulose molecules contain highly hydrophilic carboxyl and hydroxyl groups, and have a high water vapor permeability coefficient. Montmorillonite is a layered silicate composed of two layers of silicon tetrahedrons sandwiched between a layer of aluminum octahedrons, and has excellent barrier properties to water vapor. The grafting of montmorillonite and carboxymethyl cellulose forms a polymer with more pores, larger pore size and uniform distribution. This structure can provide more space for the slurry to absorb water and expand, and firmly bind water molecules under the action of hydrogen bonds, thereby improving the water retention capacity of the ceramic slurry.

[0026] 7. Carboxylation of alumina powder through surface modification can improve the dispersibility of alumina powder in solvent. Polyethylene glycol is a hydrophilic polymer. Combining the hydroxyl groups on the surface of polyethylene glycol with carboxylated alumina can further improve the water retention properties of the prepared ceramic slurry. DETAILED DESCRIPTION

[0027] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0028] The sources and models of the substances involved in the present invention are not particularly limited, and illustratively include: the silane coupling agent KH550 has a product number of S821032, which is provided by Shanghai Hongshun Biotechnology Co., Ltd.; the product number of succinic anhydride is S817605-10kg, which is provided by Beijing Naphthol Biochemical Technology Co., Ltd.; the product number of dimethylformamide is 68-12-2, which is provided by Pand (Shanghai) International Trade Co., Ltd.; the product number of alumina powder is ZTL-GCAO-035, which is provided by Yangzhou Zhongtianli Co., Ltd.; the product number of lignocellulose is IR-40011, which is provided by Shanghai Zhenzhun Biotechnology Co., Ltd.; the product number of montmorillonite is 285234-500G, which is provided by Shanghai Beinuo Biotechnology Co., Ltd.; the product number of polyethylene glycol diacrylate is P109708-25ml, which is provided by Green Union (Jining) Chemical Technology Co., Ltd.

[0029] Example 1: A non-skinning ceramic slurry and its preparation method:

[0030] Step 1: (1) 2.5 g of silane coupling agent KH550 was added to 1.3 g of succinic anhydride and 150 mL of dimethylformamide, and the mixture was stirred for 5 h to obtain a modified solution; 8 g of alumina powder was added to 110 mL of dimethylformamide, and ultrasonically dispersed for 2 h, 5 mL of the modified solution and 6 mL of deionized water were added, and the mixture was stirred for 10 h, filtered, washed, and dried at 100° C. to obtain carboxylated alumina;

[0031] (2) 5 g of carboxylated alumina was added to 50 mL of ethanol, ultrasonically dispersed, ground, and dried to obtain ceramic powder. 5 g of ceramic powder was added to 3 g of glycerol, mixed evenly, and ultrasonically dispersed for 4 h. 0.5 g of glycerol and 0.3 g of carrageenan were added and mixed to pre-dissolve the colloid. The stirring time was 10 h, the heating temperature was 80 ° C, and the stirring rate was 500 r / min to obtain a colloid.

[0032] Step 2: (1) Add 25 g of lignocellulose to 100 mL of sodium hydroxide solution, ultrasonically disperse for 12 h, filter, add 100 mL of anhydrous ethanol, stir evenly, add 12 g of chloroacetic acid, react at 70 ° C for 6 h, filter, add 50 mL of deionized water, add acetic acid dropwise to pH = 7, dry and grind to obtain carboxymethyl cellulose;

[0033] (2) 3 g of carboxymethyl cellulose was dissolved in 100 mL of deionized water and magnetically stirred for 30 min to form a carboxymethyl cellulose solution; 1 g of montmorillonite was added to 30 mL of deionized water to prepare a montmorillonite suspension; 30 mL of the montmorillonite suspension was added to 50 mL of the carboxymethyl cellulose solution, the mixture was reacted at 80° C. for 2 h, and acetic acid was added dropwise until the pH was 7 to obtain a mixed solution;

[0034] (3) Add 5 g of colloid, 3 g of polyethylene glycol diacrylate, and 2 g of potassium persulfate to 30 mL of the mixed solution, stir evenly, and heat at 200 °C for 3 h to obtain substance A;

[0035] Step 3: Take 5 g of substance A and add 7 g of polyethylene glycol as a dispersant, then put it into a ball mill and ball mill for 6 hours at a speed of 500 rpm, rotate forward for 10 minutes, reverse for 9 minutes, and rest for 3 minutes. Then add 5 g of substance A and ball mill for 12 hours at a speed of 500 rpm, rotate forward for 10 minutes, reverse for 9 minutes, and rest for 3 minutes. Then adjust the ball mill speed to 5 r / min, ball mill for 1 hour, and perform preliminary degassing treatment to obtain an alumina ceramic slurry;

[0036] Step 4: (1) After the alumina ceramic slurry is taken out from the ball mill, it is added to a diaphragm pump, and the discharge compressed air pressure is 0.1 MPa; then the alumina ceramic slurry is filtered using two filters in series, the first filter is 200 mesh and the second filter is 500 mesh; the degassing tank is heated in advance at 32°C for 25 minutes in a water circulation, and the alumina slurry is discharged at a flow rate of 6 L / min to 30% of the volume of the degassing tank, the discharge pressure is 0.1 MPa, the discharge viscosity is 1000 cp, the discharge solid content is 50%, the initial tank upper slurry temperature is 35°C, and the initial tank lower slurry temperature is 30.3°C;

[0037] (2) The degassing speed is 30r / min, the vacuum degree of the degassing tank is -50kPa, the water circulation temperature is 30℃, the time is 20min, and the temperature of the degassing tank is kept constant at 39.2℃ for the first degassing; the vacuum degree of the degassing tank is adjusted to -85kPa, the water circulation temperature is 30℃, and the time is 22h, and the second degassing is performed, so that the slurry casting viscosity is 6000cp and the casting solid content is 58%; the degassing speed is adjusted to 5r / min, the vacuum degree of the degassing tank is -70KPa, the water circulation temperature is 30℃, and the time is 2h, and the third degassing is performed, so that the internal viscosity and solid content of the slurry are 1%, and the difference in green embryo thickness is 15um, thereby preparing a ceramic slurry without skinning.

[0038] Example 2: A non-skinning ceramic slurry and its preparation method:

[0039] Step 1: (1) 2.5 g of silane coupling agent KH550 was added to 1.3 g of succinic anhydride and 150 mL of dimethylformamide, and the mixture was stirred for 7 h to obtain a modified solution; 8 g of alumina powder was added to 110 mL of dimethylformamide, and ultrasonically dispersed for 4 h, 5 mL of the modified solution and 6 mL of deionized water were added, and the mixture was stirred for 12 h, filtered, washed, and dried at 120° C. to obtain carboxylated alumina;

[0040] (2) 5 g of carboxylated alumina was added to 50 mL of ethanol, ultrasonically dispersed, ground, and dried to obtain ceramic powder. 5 g of the ceramic powder was added to 3 g of glycerol, mixed evenly, and ultrasonically dispersed for 6 h. 0.5 g of glycerol and 0.3 g of carrageenan were added and mixed to pre-dissolve the colloid. The stirring time was 12 h, the heating temperature was 100 ° C, and the stirring rate was 500 r / min to obtain a colloid.

[0041] Step 2: (1) Add 25 g of lignocellulose to 100 mL of sodium hydroxide solution, ultrasonically disperse for 14 h, filter, add 100 mL of anhydrous ethanol, stir evenly, add 12 g of chloroacetic acid, react at 90 ° C for 8 h, filter, add 50 mL of deionized water, add acetic acid dropwise to pH = 7, dry and grind to obtain carboxymethyl cellulose;

[0042] (2) 3 g of carboxymethyl cellulose was dissolved in 100 mL of deionized water and magnetically stirred for 40 min to form a carboxymethyl cellulose solution; 1 g of montmorillonite was added to 30 mL of deionized water to prepare a montmorillonite suspension; 30 mL of the montmorillonite suspension was added to 50 mL of the carboxymethyl cellulose solution, the mixture was reacted at 100° C. for 4 h, and acetic acid was added dropwise until the pH was 7 to obtain a mixed solution;

[0043] (3) Add 5 g of colloid, 3 g of polyethylene glycol diacrylate, and 2 g of potassium persulfate to 30 mL of the mixed solution, stir evenly, and heat at 220 °C for 5 h to obtain substance A;

[0044] Step 3: Take 5 g of substance A and add 7 g of polyethylene glycol as a dispersant, then put it into a ball mill and ball mill for 8 hours at a speed of 500 rpm, rotate forward for 12 minutes, reverse for 11 minutes, and rest for 5 minutes. Then add 5 g of substance A and ball mill for 14 hours at a speed of 500 rpm, rotate forward for 12 minutes, reverse for 11 minutes, and rest for 5 minutes. Then adjust the ball mill speed to 20 r / min and ball mill for 3 hours to perform preliminary degassing treatment to obtain an alumina ceramic slurry;

[0045] Step 4: (1) After the alumina ceramic slurry is taken out from the ball mill, it is added to a diaphragm pump, and the discharge compressed air pressure is 0.5 MPa; then the alumina ceramic slurry is filtered using two filters in series, the first filter is 200 mesh and the second filter is 500 mesh; the degassing tank is heated in advance at 39°C for 20 minutes in a water circulation, and the alumina slurry is discharged to 70% of the volume of the degassing tank at a flow rate of 9 L / min, the discharge pressure is 0.3 MPa, the discharge viscosity is 5000 cp, the discharge solid content is 70%, the initial tank upper slurry temperature is 37°C, and the initial tank lower slurry temperature is 31.3°C;

[0046] (2) The degassing speed is 80r / min, the vacuum degree of the degassing tank is -70kPa, the water circulation temperature is 45℃, the time is 60min, and the temperature of the degassing tank is kept constant at 39.2℃ for the first degassing; the degassing speed is adjusted to 90r / min, the vacuum degree of the degassing tank is -95kPa, the water circulation temperature is 45℃, and the time is 24h, and the second degassing is performed, so that the slurry casting viscosity is 12000cp and the casting solid content is 66%; the degassing speed is adjusted to 30r / min, the vacuum degree of the degassing tank is -80KPa, the water circulation temperature is 40℃, and the time is 12h, and degassing is performed, so that the internal viscosity and solid content of the slurry are 1%, and the difference in green embryo thickness is 15um, thereby preparing a ceramic slurry without skinning.

[0047] Example 3: A non-skinning ceramic slurry and its preparation method:

[0048] Step 1: (1) 2.5 g of silane coupling agent KH550 was added to 1.3 g of succinic anhydride and 150 mL of dimethylformamide, and the mixture was stirred for 6 h to obtain a modified solution; 8 g of alumina powder was added to 110 mL of dimethylformamide, and ultrasonically dispersed for 3 h, and 5 mL of the modified solution and 6 mL of deionized water were added, filtered, washed, and dried at 110° C. to obtain carboxylated alumina;

[0049] (2) 5 g of carboxylated alumina was added to 50 mL of ethanol, ultrasonically dispersed, ground, and dried to obtain ceramic powder. 5 g of ceramic powder was added to 3 g of glycerol, mixed evenly, and ultrasonically dispersed for 5 h. 0.5 g of glycerol and 0.3 g of carrageenan were added and mixed to pre-dissolve the colloid. The stirring time was 11 h, the heating temperature was 90 ° C, and the stirring rate was 500 r / min to obtain a colloid.

[0050] Step 2: (1) Add 25 g of lignocellulose to 100 mL of sodium hydroxide solution, ultrasonically disperse for 13 h, filter, add 100 mL of anhydrous ethanol, stir evenly, add 12 g of chloroacetic acid, react at 80°C for 7 h, filter, add 50 mL of deionized water, add acetic acid dropwise to pH = 7, dry, and grind to obtain carboxymethyl cellulose;

[0051] (2) 3 g of carboxymethyl cellulose was dissolved in 100 mL of deionized water and magnetically stirred for 35 min to form a carboxymethyl cellulose solution; 1 g of montmorillonite was added to 30 mL of deionized water to prepare a montmorillonite suspension; 30 mL of the montmorillonite suspension was added to 50 mL of the carboxymethyl cellulose solution, the mixture was reacted at 90° C. for 3 h, and acetic acid was added dropwise until the pH was 7 to obtain a mixed solution;

[0052] (3) Add 5 g of colloid, 3 g of polyethylene glycol diacrylate, and 2 g of potassium persulfate to 30 mL of the mixed solution, stir well, and heat at 210 °C for 4 h to obtain substance A;

[0053] Step 3: Take 5 g of substance A and add 7 g of polyethylene glycol as a dispersant, then put it into a ball mill and ball mill it for 7 hours at a speed of 500 rpm, rotate forward for 11 minutes, reverse for 10 minutes, and rest for 4 minutes. Then add 5 g of substance A and ball mill it for 13 hours at a speed of 500 rpm, rotate forward for 11 minutes, reverse for 10 minutes, and rest for 4 minutes. Then adjust the ball mill speed to 12 r / min, ball mill for 2 hours, and perform preliminary defoaming treatment to obtain an alumina ceramic slurry;

[0054] Step 4: (1) After the alumina ceramic slurry is taken out from the ball mill, it is added to a diaphragm pump with a discharge compressed air pressure of 0.3 MPa; then the alumina ceramic slurry is filtered using two filters in series, the first filter is 200 mesh and the second filter is 500 mesh; the degassing tank is heated in advance at 35°C for 30 minutes in a water circulation, and the alumina slurry is discharged to 50% of the volume of the degassing tank at a flow rate of 7 L / min, the discharge pressure is 0.15 MPa, the discharge viscosity is 3000 cp, the discharge solid content is 70%, the initial tank upper slurry temperature is 34.5°C, and the initial tank lower slurry temperature is 30.2°C;

[0055] (2) The degassing speed is 55r / min, the vacuum degree of the degassing tank is -60kPa, the water circulation temperature is 37℃, the time is 40min, and the temperature of the degassing tank is kept constant at 39.5℃ for the first degassing; the degassing speed is adjusted to 60r / min, the vacuum degree of the degassing tank is -90kPa, the water circulation temperature is 35℃, and the time is 23h, and the second degassing is performed, so that the slurry casting viscosity is 8000cp and the casting solid content is 52%; the degassing speed is 15r / min, the vacuum degree of the degassing tank is -75KPa, the water circulation temperature is 35℃, and the time is 7h, and the third degassing is performed, so that the internal viscosity and solid content of the slurry are 1%, and the green embryo thickness difference is 15um, thereby preparing a ceramic slurry without skinning.

[0056] Comparative Example 1: The filter was changed to 500 mesh, and the rest was referred to Example 1. The specific operations were as follows:

[0057] Step 4: (1) After the alumina ceramic slurry is taken out from the ball mill, it is added to a diaphragm pump with a discharge compressed air pressure of 0.1 MPa; then the alumina ceramic slurry is filtered with a 500-mesh filter; the degassing tank is heated in advance at 43°C for 32 minutes by water circulation, and the alumina slurry is discharged at a flow rate of 15 L / min to 30% of the volume of the degassing tank, with a discharge pressure of 0.55 MPa, a discharge viscosity of 1000 cp, a discharge solid content of 60%, an initial tank upper slurry temperature of 35.1°C, and an initial tank lower slurry temperature of 30.6°C;

[0058] (2) The degassing speed is 30r / min, the vacuum degree of the degassing tank is -50kPa, the water circulation temperature is 30℃, the time is 20min, and the temperature of the degassing tank is kept constant at 29.5℃ for the first degassing; the vacuum degree of the degassing tank is adjusted to -77kPa, the speed is 50r / min, the water circulation temperature is 29℃, and the time is 22h, and the second degassing is performed, so that the slurry casting viscosity is 6000cp and the casting solid content is 58%; the degassing speed is adjusted to 32r / min, the vacuum degree of the degassing tank is -85KPa, the water circulation temperature is 37℃, and the time is 2h, and the third degassing is performed, so that the internal viscosity and solid content of the slurry are 1%, and the difference in green embryo thickness is 15um, thereby preparing a ceramic slurry without skinning.

[0059] Comparative Example 2: The filter was changed to 200 mesh, and the rest was referred to Example 1. The specific operations were as follows:

[0060] Step 4: (1) After the alumina ceramic slurry is taken out from the ball mill, it is added to a diaphragm pump with a discharge compressed air pressure of 0.1 MPa; then the alumina ceramic slurry is filtered with a filter of 200 mesh; the degassing tank is heated in advance at 25°C for 18 minutes by water circulation, and the alumina slurry is discharged at a flow rate of 8 L / min to 30% of the volume of the degassing tank, with a discharge pressure of 0.05 MPa, a discharge viscosity of 1000 cp, a discharge solid content of 75%, an initial tank upper slurry temperature of 36.3°C, and an initial tank lower slurry temperature of 31.8°C;

[0061] (2) The degassing speed is 30r / min, the vacuum degree of the degassing tank is -50kPa, the water circulation temperature is 30℃, the time is 20min, and the temperature of the degassing tank is kept constant at 47℃ for the first degassing; the vacuum degree of the degassing tank is adjusted to -97kPa, the speed is 100r / min, the water circulation temperature is 37℃, and the time is 22h, and the second degassing is performed, so that the slurry casting viscosity is 6000cp and the casting solid content is 58%; the degassing speed is adjusted to 10r / min, the vacuum degree of the degassing tank is -68KPa, the water circulation temperature is 29℃, and the time is 2h, and the third degassing is performed, so that the internal viscosity and solid content of the slurry are 1%, and the difference in green embryo thickness is 15um, thereby preparing a ceramic slurry without skinning.

[0062] Comparative Example 3: Carboxymethyl cellulose and montmorillonite were not added, and the rest was referred to Example 1. The specific operations were as follows:

[0063] Step 2: Add 3 g of polyethylene glycol diacrylate and 2 g of potassium persulfate to 5 g of colloid, stir well, and heat at 200°C for 3 h to obtain substance A.

[0064] Comparative Example 4: Without adding polyethylene glycol diacrylate, the rest is referred to Example 1, and the specific operations are as follows:

[0065] Step 2: (1) Add 25 g of lignocellulose to 100 mL of sodium hydroxide solution, ultrasonically disperse for 12 h, filter, add 100 mL of anhydrous ethanol, stir evenly, add 12 g of chloroacetic acid, react at 70 ° C for 6 h, filter, add 50 mL of deionized water, add acetic acid dropwise to pH = 7, dry and grind to obtain carboxymethyl cellulose;

[0066] (2) 3 g of carboxymethyl cellulose was dissolved in 100 mL of deionized water and magnetically stirred for 30 min to form a carboxymethyl cellulose solution; 1 g of montmorillonite was added to 30 mL of deionized water to prepare a montmorillonite suspension; 30 mL of the montmorillonite suspension was added to 50 mL of the carboxymethyl cellulose solution, the mixture was reacted at 80° C. for 2 h, and acetic acid was added dropwise until the pH was 7 to obtain a mixed solution;

[0067] (3) Add 5 g of colloid and 2 g of potassium persulfate to 30 mL of the mixed solution, stir evenly, and heat at 200 °C for 3 h to obtain substance A.

[0068] Comparative Example 5: The alumina powder was not carboxylated. The rest of the process was similar to that of Example 1. The specific operation was as follows:

[0069] Step 1: Add 5 g of alumina to 50 mL of ethanol, ultrasonically disperse, grind, and dry to obtain ceramic powder. Add 3 g of glycerol to 5 g of ceramic powder, mix evenly, and ultrasonically disperse for 4 hours. Then add 0.5 g of glycerol and 0.3 g of carrageenan and mix and stir to pre-dissolve the colloid. The stirring time is 10 hours, the heating temperature is 80°C, and the stirring rate is 500 r / min to obtain a colloid.

[0070] Experiment 1: 200 mL of the ceramic slurries prepared in Examples 1 to 3 and Comparative Examples 1 to 2 were taken respectively. In Examples 1 to 3, the ceramic slurries were filtered using two filters in series, one filter was 200 mesh and the second filter was 500 mesh; in Comparative Example 1, the ceramic slurry was filtered using a 500 mesh filter; in Comparative Example 2, the ceramic slurry was filtered using a 200 mesh filter; the slurries were allowed to stand for 5 hours and the state of the ceramic slurries was observed. The experimental data are as follows:

[0071] Table 1

[0072] Examples Slurry state Example 1 Slurry is stable Example 2 Slurry is stable Example 3 Slurry is stable Comparative Example 1 Slurry crust Comparative Example 2 Slurry crust

[0073] Conclusion: From the above experimental data, it can be seen that Examples 1 to 3 are filtered with two filters in series, one filter with 200 mesh and the second filter with 500 mesh, and the prepared slurry is in a stable state without crusting; Comparative Example 1 is filtered with a 500 mesh filter, and the slurry is crusted; Comparative Example 2 is filtered with a 200 mesh filter, and a crust is formed on the surface of the slurry; so the filtration method should be to use two filters in series, one filter with 200 mesh and the second filter with 500 mesh; the designed filter screen combination is a 200 mesh and 500 mesh filter screen combination to filter out the ceramic slurry crusting and slurry particles during the ball milling process, and squeeze out large bubbles in the ceramic slurry; the tank body is heated to avoid temperature difference contact with the crust, increase the discharge flow rate control, and avoid the filter screen from being stretched and damaged, resulting in poor filtration effect.

[0074] Experiment 2: Take 200 mL of the ceramic slurry prepared in Examples 1 to 3 and Comparative Examples 1 to 2 respectively. The vacuum degree of the degassing tank of Example 1 is -70 MPa, the vacuum degree of the degassing tank of Example 2 is -80 MPa, the vacuum degree of the degassing tank of Example 3 is -75 MPa, the vacuum degree of the degassing tank of Comparative Example 1 is -85 MPa, and the vacuum degree of the degassing tank of Comparative Example 2 is -68 MPa. Let it stand for 5 hours and observe the surface state of the slurry prepared in Examples 1 to 3 and Comparative Examples 1 to 2 after degassing. The data are as follows:

[0075] Table 2

[0076] Examples Slurry surface state Example 1 Smooth, no bubbles, no crusting Example 2 Smooth, no bubbles, no crusting Example 3 Smooth, no bubbles, no crusting Comparative Example 1 Bubbles continue to form Comparative Example 2 Skin appears on the surface of the slurry

[0077] Conclusion: From the above experimental data, it can be seen that: no bubbles and no crusting are produced on the surface of the slurry prepared in Examples 1 to 3; the vacuum degree of the degassing tank in Comparative Example 1 is -85MPa, and bubbles are produced on the surface of the slurry; the vacuum degree of the degassing tank in Comparative Example 2 is -68MPa, and crusting appears on the surface of the slurry; the ball mill degassing is designed to reduce frictional heat through low speed, inhibit the evaporation of volatile components, and reduce the formation of crusting; the material flow speed is slow at low speed, and the gas has more time to escape through the gaps between the ceramic slurries, and the slow movement inhibits retained bubbles.

[0078] Experiment 3: 200 mL of the ceramic slurries prepared in Examples 1 to 3 and Comparative Examples 1 to 2 were taken respectively. The degassing tanks of Examples 1 to 3 were degassed at a constant temperature of 39.2° C., the degassing tank of Comparative Example 1 was degassed at a constant temperature of 29.5° C., and the degassing tank of Comparative Example 1 was degassed at a constant temperature of 47° C. After standing for 5 hours, the surface conditions of the slurries prepared in Examples 1 to 3 and Comparative Examples 1 to 2 were observed. The specific data are as follows:

[0079] Table 3

[0080] Examples Slurry surface state Example 1 The surface is smooth, without crust, and bubbles are floating Example 2 The surface is smooth, without crust, and bubbles are floating Example 3 The surface is smooth, without crust, and bubbles are floating Comparative Example 1 There are wrinkles and crusts on the surface, and bubbles are floating Comparative Example 2 There are wrinkles and crusts on the surface, and bubbles are floating

[0081] Conclusion: From the above experimental data, it can be seen that after degassing at a constant temperature of 39.2°C, the slurry surface of Examples 1 to 3 is smooth, without crusting, and bubbles float out; after degassing at a constant temperature of 29.5°C, the slurry surface of Comparative Example 1 is wrinkled and crusted, and bubbles float out; after degassing at a constant temperature of 47°C, the slurry surface of Comparative Example 2 is wrinkled and crusted, and bubbles float out; so temperature changes can cause slurry crusting.

[0082] Experiment 4: Take 200mL of ceramic slurry and observe the state of the slurry under different negative pressure conditions. In Example 1, the vacuum degree in the degassing tank is -85kPa, in Example 2, the vacuum degree in the degassing tank is -95kPa, in Example 3, the vacuum degree in the degassing tank is -90kPa, in Comparative Example 1, the vacuum degree in the degassing tank is -77kPa, and in Comparative Example 2, the vacuum degree in the degassing tank is -97kPa. The specific data are as follows:

[0083] Table 4

[0084] Examples Slurry state Example 1 Boiling solvent removal Example 2 Boiling solvent removal Example 3 Boiling solvent removal Comparative Example 1 No boiling solvent is released Comparative Example 2 Boiling, slurry splashing

[0085] Conclusion: It can be seen from the above experimental data that: after the second degassing of the ceramic slurry prepared in Examples 1 to 3, the slurry boils and the solvent is released; in Comparative Example 1, the vacuum degree in the degassing tank is -77kpa, the slurry does not boil and the solvent is not released; in Comparative Example 2, the vacuum degree in the degassing tank is -97kpa, the slurry boils and sputters; when the bubbles are lifted to the negative pressure environment of the slurry surface, the bubbles and solvent in the slurry are guided to the liquid surface for release, so the slurry boils and the solvent is released, but the negative pressure is too high, the slurry boils and sputters; the negative pressure is too low, the slurry does not boil and the solvent is not released.

[0086] Experiment 3: 200 mL of the ceramic slurries prepared in Example 1, Comparative Example 3, Comparative Example 4, and Comparative Example 5 were taken, allowed to stand for 5 hours, and the surface state of the slurries was observed. The test results are as follows:

[0087] Table 5

[0088] Examples Slurry surface state Example 1 Smooth, no bubbles, no crusting Comparative Example 3 Bubbles and crust appear on the slurry surface Comparative Example 4 Skin appears on the surface of the slurry Comparative Example 5 Skin appears on the surface of the slurry

[0089] Conclusion: The surface of the slurry prepared in Example 1 is smooth and has no bubble crusting. The slurry prepared in Comparative Example 3 does not add montmorillonite, and crusting and bubbles appear on the slurry surface. The slurry prepared in Comparative Example 4 does not add polyethylene glycol diacrylate, and a crusting appears on the slurry surface. The slurry prepared in Comparative Example 5 does not carboxylate the alumina powder, and a crusting appears on the slurry surface. This is because the montmorillonite and carboxymethyl cellulose are grafted, and the polymer pores formed are more, larger in size and evenly distributed. This structure can provide more space for the slurry to absorb water and expand, and under the action of hydrogen bonds, the water is absorbed by the slurry. The molecules are firmly bound, thereby improving the water retention capacity of the ceramic slurry, reducing water volatilization, and no skinning on the slurry surface; the polyethylene glycol diacrylate molecular chain is adsorbed on the surface of the alumina particles, forming a steric hindrance layer, and the electrostatic repulsion and steric hindrance cause the particles to disperse, and the particle surface is fully wetted by water, which improves the overall fluidity of the slurry and reduces the occurrence of slurry skinning; polyethylene glycol is a hydrophilic polymer. Combining the hydroxyl groups on the surface of polyethylene glycol with carboxylated alumina can further improve the water retention performance of the prepared ceramic slurry and reduce the occurrence of skinning.

[0090] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

Claims

1. A non-skinning ceramic slurry and a preparation method thereof, characterized in that: The following steps are involved: Step 1: Add alumina ceramic slurry into the diaphragm pump, discharge, compress air, the pressure is 0.1 ~ 0.5MPa; filter, heat the degassing tank, and discharge the alumina ceramic slurry into the degassing tank; Step 2: Maintain the degassing tank at a constant temperature and perform the first degassing; adjust the vacuum degree of the degassing tank and perform the second degassing; adjust the degassing speed and the vacuum degree of the degassing tank and perform the third degassing to obtain a ceramic slurry without skinning.

2. The method for preparing a non-skinning ceramic slurry according to claim 1, wherein: In step 1, filtration is performed using two filters connected in series, one filter is 200 mesh and the second filter is 500 mesh.

3. The method for preparing a non-skinning ceramic slurry according to claim 1, wherein: In step 1, the discharging parameters are: discharging pressure of 0.1-0.55 MPa, discharging viscosity of 1000-5000 cp, and discharging solid content of 50-75%.

4. The method for preparing a non-skinning ceramic slurry according to claim 1, wherein: In step 2, during the first degassing, the degassing speed is 30 to 90 r / min, the vacuum degree of the degassing tank is -50 kPa to (-70 kPa), and the time is 20 to 60 min; during the second degassing, the vacuum degree of the degassing tank is -85 kPa to (-97 kPa), and the time is 22 to 24 h, so that the slurry casting viscosity is 6000 to 12000 cp and the casting solid content is 58 to 66%; during the third degassing, the degassing speed is 5 to 32 r / min, the vacuum degree of the degassing tank is -70 kPa to (-85 kPa), and the time is 2 to 12 h.

5. The method for preparing a non-skinning ceramic slurry according to claim 1, wherein: The preparation method of the alumina ceramic slurry comprises the following steps: Step A: adding carboxylated alumina to ethanol, ultrasonically dispersing, grinding, and drying to obtain ceramic powder; adding the ceramic powder to glycerol, ultrasonically dispersing for 4-6 hours; adding glycerol and carrageenan, mixing, and heating and stirring for 10-12 hours to obtain a colloid; Step B: adding colloid, polyethylene glycol diacrylate and potassium persulfate to the mixed solution, stirring evenly, and heating to obtain substance A; Step C: Take half of the substance A and add polyethylene glycol, ball mill, and ball mill for 6 to 8 hours at a speed of 500 rpm, rotate forward for 10 to 12 minutes, reverse for 9 to 11 minutes, and rest for 3 to 5 minutes. Add the remaining substance A, and ball mill for 12 to 14 hours at a speed of 500 rpm, rotate forward for 10 to 12 minutes, reverse for 9 to 11 minutes, and rest for 3 to 5 minutes. Adjust the speed to 5 to 20 r / min and ball mill for 1 to 3 hours to obtain an alumina ceramic slurry.

6. The method for preparing a non-skinning ceramic slurry according to claim 5, characterized in that: The preparation method of the mixed solution comprises the following steps: adding carboxymethyl cellulose to deionized water and stirring magnetically to prepare a carboxymethyl cellulose solution; adding montmorillonite to deionized water to prepare a montmorillonite suspension; adding the montmorillonite suspension to the carboxymethyl cellulose solution, reacting for 2 to 4 hours, and adding acetic acid dropwise until the pH reaches 7 to obtain a mixed solution.

7. The method for preparing a non-skinning ceramic slurry according to claim 5, wherein: The preparation method of the carboxylated alumina comprises the following steps: adding succinic anhydride and dimethylformamide to a silane coupling agent KH550, mixing and stirring for 5 to 7 hours to obtain a modified liquid; adding dimethylformamide to alumina powder, ultrasonically dispersing for 2 to 4 hours, adding the modified liquid and deionized water, stirring for 10 to 12 hours, filtering, washing, and drying to obtain the carboxylated alumina.

8. The method for preparing a non-skinning ceramic slurry according to claim 6, wherein: The preparation method of the carboxymethyl cellulose comprises the following steps: adding lignocellulose to a sodium hydroxide solution, ultrasonically dispersing the solution for 12 to 14 hours, filtering the solution, adding anhydrous ethanol, stirring the solution evenly, adding chloroacetic acid, filtering the solution with suction, adding deionized water, dropping acetic acid until the solution has a pH of 7, drying the solution, and grinding the solution to obtain the carboxymethyl cellulose. 9 . The skin-free ceramic slurry prepared according to the method for preparing a skin-free ceramic slurry according to any one of claims 1 to 8 .