A water-based tape casting ceramic preparation method, slurry and ceramic

Abstract

The application discloses a water-based tape casting ceramic preparation method, a slurry and a ceramic, relates to the technical field of ceramic preparation, and the preparation method comprises the following steps: mixing a powder, a dispersing agent, water and a borate-containing solution to obtain a first slurry; the powder comprises ceramic powder and glass powder; a PH regulator is added to the first slurry to adjust the pH value of the first slurry to a preset pH value; the first slurry is stirred, and a binder is added dropwise to the first slurry in the form of liquid drops to obtain a second slurry, wherein the binder is polyvinyl alcohol; the second slurry is used as a slurry for casting to be leveled, and a casting film strip is obtained after drying; the casting film strip is subjected to a pressing treatment to obtain a green body; and the green body is subjected to a sintering treatment to obtain a ceramic matrix. The film strip prepared by the application has high toughness and is easy to press; after heat pressing, the film strip will not crack during sintering, and the prepared ceramic has high quality.

Description

Technical Field

[0001] This invention relates to the field of ceramic preparation technology, specifically to a method for preparing water-based cast ceramics, a slurry, and ceramics. Background Technology

[0002] Tape casting is a commonly used method for ceramic preparation, capable of producing high-quality, ultra-thin ceramic substrates. Tape casting technology is widely used in industrial production due to its simple equipment, continuous operation, high production efficiency, and low cost of film preparation. Currently, the most commonly used method is organic tape casting, but it still has many problems: (1) The green body formed by organic casting retains a large amount of organic matter, leading to cracking and deformation of the green body during the later debinding process. (2) The slurry prepared by organic casting has a low solid content, causing the ceramic powder to settle during drying, resulting in a density gradient between the upper and lower surfaces of the green body. (3) During sintering, due to insufficient bonding of the green body, it is prone to blistering, cracking, and deformation, and is also brittle with significant dimensional changes. (4) The use of organic matter makes equipment cleaning difficult and increases equipment maintenance costs. Therefore, it is necessary to research a green and effective tape casting method for ceramic substrates to facilitate large-scale production.

[0003] To overcome the shortcomings of organic casting technology, water-based casting technology has also been adopted. However, water-based casting technology still faces significant technical challenges. The powder has poor wettability with water, which easily generates a large number of bubbles, making defoaming difficult. The quality of the film is poor, and cracking is prone to occur during the glue removal process. Therefore, it cannot adequately meet the needs of modern chip electronic components. Summary of the Invention

[0004] The main technical problem solved by this invention is that existing water-based casting methods cannot meet the needs of chip electronic components.

[0005] According to a first aspect, one embodiment provides a method for preparing water-based cast ceramics, comprising:

[0006] The powder, dispersant, water, and borate-containing solution are mixed to obtain the first slurry; the powder includes ceramic powder and glass powder.

[0007] Add a pH adjuster to the first slurry to adjust its pH to the preset pH.

[0008] The first slurry is stirred and a binder is added dropwise to the first slurry to obtain a second slurry. The binder is polyvinyl alcohol.

[0009] The second slurry is used as the slurry for casting and leveled. After drying, a cast film tape is obtained.

[0010] The cast film strip is pressed together to obtain a green blank;

[0011] The green body is sintered to obtain a ceramic matrix.

[0012] According to the second aspect, one embodiment provides a ceramic made using the preparation method described in the first aspect.

[0013] According to a third aspect, one embodiment provides a water-based cast ceramic slurry, comprising powder, dispersant, water, and a solution containing borate; the powder comprises ceramic powder and glass powder;

[0014] It also includes pH adjusters and binders, with the binder being a polyvinyl alcohol solution.

[0015] According to the above embodiments, the water-based cast ceramic preparation method, slurry, and ceramic are achieved by adding a borate-containing solution to the slurry and adding a polyvinyl alcohol solution in the form of droplets. The droplets and the slurry form a micro-reaction vessel, which coats the nearby ceramic powder and glass powder. Each droplet forms a microgel with the slurry, thereby achieving the purpose of controlling the uniform gelation of the entire system. The prepared film tape is tough, easy to press, and will not crack after hot pressing and sintering. The resulting ceramic is of high quality. Attached Figure Description

[0016] Figure 1 This is a schematic flowchart of a water-based cast ceramic preparation method provided in one embodiment of this application. Detailed Implementation

[0017] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings. Similar elements in different embodiments are referred to by associated similar element reference numerals. In the following embodiments, many details are described to facilitate a better understanding of this application. However, those skilled in the art will readily recognize that some features may be omitted in different situations, or may be replaced by other elements, materials, or methods. In some cases, certain operations related to this application are not shown or described in the specification. This is to avoid obscuring the core parts of this application with excessive description. For those skilled in the art, detailed description of these related operations is not necessary; they can fully understand the related operations based on the description in the specification and general technical knowledge in the art.

[0018] Furthermore, the features, operations, or characteristics described in the specification can be combined in any suitable manner to form various embodiments. At the same time, the steps or actions in the method description can be rearranged or adjusted in a manner obvious to those skilled in the art. Therefore, the various orders in the specification and drawings are only for the clear description of a particular embodiment and do not imply a necessary order, unless otherwise stated that a particular order must be followed.

[0019] The serial numbers assigned to components in this document, such as "first" and "second," are used only to distinguish the described objects and have no sequential or technical meaning. The terms "connection" and "linkage" used in this application, unless otherwise specified, include both direct and indirect connections (linkages).

[0020] Water-based tape casting technology is a variant of tape casting technology, characterized by the use of water as the primary solvent or medium in the preparation process. Compared to traditional organic solvents, water-based tape casting technology has advantages such as being environmentally friendly, safe, and cost-effective, and has therefore received widespread attention and application in recent years.

[0021] However, the limitations of water-based casting technology in ceramic preparation are also quite obvious, for example:

[0022] The drying process is difficult to control: water-based casting technology is prone to cracking during the drying process, requiring precise control.

[0023] Specific material suitability: Not all materials are suitable for water-based casting technology. Some specific materials may have poor solubility or high reactivity in water.

[0024] Therefore, existing water-based casting methods suffer from problems such as poor wettability of powder to water, poor film quality, and cracking during the debinding process (after sintering).

[0025] Example 1

[0026] like Figure 1 As shown in the embodiments of this application, a method for preparing water-based cast ceramics (hereinafter referred to as the preparation method or method) is provided, which may include:

[0027] The first slurry preparation step involves mixing powder, dispersant, water, and a borate-containing solution to initially obtain a slurry. The slurry obtained in this step is defined as the first slurry. The powder may include ceramic powder and glass powder. The water can be pure water or deionized water. For ceramic preparation where impurities are not critical, ordinary water can also be used.

[0028] In some embodiments, the powder may also include a pore-forming agent. The pore-forming agent can form a microporous structure in the ceramic material, thereby reducing the overall density and increasing the permeability of the ceramic. During sintering, the pore-forming agent can leave pores in the ceramic material, which helps to release combustion products and gases, reduces internal pressure during sintering, and is beneficial to the sintering uniformity and stability of the ceramic material.

[0029] For example, ball milling can be used to mix and grind powder, dispersant, solvent and borate solution so that each component is uniformly dispersed in the first slurry. This ball milling step is defined as a first ball milling.

[0030] In the above steps, the powder, dispersant, water, and borate-containing solution are initially mixed to fully disperse the powder in the slurry. Unlike existing water-based casting methods, in this embodiment, a borate-containing solution is added to the first slurry, allowing the borate ions to undergo a gel reaction with polyvinyl alcohol in subsequent steps.

[0031] Since the gelation reaction rate of borate ions with polyvinyl alcohol is affected by the pH value of the slurry, the reaction rate of subsequent gelation reactions can be controlled by adjusting the pH value of the slurry. In some embodiments, in the first slurry preparation step, after mixing the powder, dispersant, solvent, and borate-containing solution, the following may also be included:

[0032] The pH adjustment step involves adding a pH adjuster to the first slurry to adjust its pH value to a preset value. The preset pH value can be 7-10, and the pH adjuster can be an alkaline solution, such as ammonia. Depending on the actual powder composition, an alkaline solution with common ionic components, such as sodium bicarbonate, can also be selected. If the pH value of the first slurry meets the requirements, the pH adjuster does not need to be added, and the above pH adjustment step can be omitted.

[0033] The process involves adding a binder dropwise, stirring the first slurry, and then adding the binder (polyvinyl alcohol) dropwise to the first slurry. The slurry containing polyvinyl alcohol is defined as the second slurry. Continuous stirring ensures the generated gel is fully dispersed in the second slurry. After one ball milling cycle, stirring can continue, with the binder added during the stirring process. The stirring speed can be 50 r / min to 150 r / min.

[0034] In the above steps, the polyvinyl alcohol solution is added to the slurry containing borate ions in the form of droplets. The droplets and the slurry form a micro-reaction vessel (this reaction is also called microdroplet chemical reaction), which coats the nearby ceramic powder, glass powder and pore-forming agent (if present). Each droplet forms a microgel with the slurry, thereby achieving the purpose of controlling the uniform gelation of the entire system.

[0035] Polyvinyl alcohol (PVA) can react with solutions containing borate ions to produce polymeric borates. For example, a condensation reaction occurs between boric acid and PVA to form polymeric borates; the product is gel-like, and this reaction can be called a gel reaction.

[0036] For example, microfluidic control technology can be used to form micro-droplets of polyvinyl alcohol solution and add them to the first slurry. The borate ions in the first slurry and the polyvinyl alcohol solution can easily react to form a gel. The gel formation rate can be controlled by five parameters: borate ion concentration, solution (slurry) pH value, polyvinyl alcohol concentration, polyvinyl alcohol addition amount, and droplet size. Of course, the chemical reaction is also related to temperature, but the production environment is generally constant temperature. Therefore, the effects of temperature will not be described in this application embodiment.

[0037] Therefore, in the first slurry preparation step, the gel formation rate can be controlled by adjusting the concentration of the borate-containing solution and the pH value of the slurry, and in the binder addition step, the concentration of polyvinyl alcohol, the amount of polyvinyl alcohol added, and the droplet size can be adjusted.

[0038] The droplet size of polyvinyl alcohol (PVA) is a key control parameter. Larger droplets contain more reactants and exhibit more vigorous cross-linking. However, when excessive borate ions cross-link with PVA, the degree of cross-linking increases significantly, resulting in larger microgel particles. Multiple particles become entangled, leading to the formation of a large-area colloid in the slurry, poor raw material dispersion, and negatively impacting the casting effect. In some embodiments, the binder is added to the slurry in droplet form during the binder addition step, which may include:

[0039] Step 201: Control the droplet size of the binder to be 10μm to 1000μm; determine the amount of binder to be added based on the mass of the powder, which can be 50% to 150% of the mass of the powder.

[0040] This application's embodiments control the gel size by adjusting the size of the PVA droplets, thus preventing excessively large gels from affecting the casting effect. This is because a large amount of PVA is introduced into the first slurry instantaneously, forming large gel clumps in a short time, which affects the molding effect. Therefore, in existing water-based casting techniques, PVA is avoided if the slurry contains borate ions. This application, however, overcomes this technical problem by adding the binder to the first slurry in droplet form, controlling the droplet size and amount, thereby forming a micro-reaction vessel and ensuring the molding effect.

[0041] The first casting step, after completing the adhesive addition step, yields a second slurry that can be directly used for leveling during casting. After drying, a cast film tape is obtained.

[0042] In some embodiments, to improve the quality of the cast film, plasticizers and / or defoamers can be added to the second slurry as synergistic components to obtain a third slurry for leveling as a slurry for casting.

[0043] In the above embodiments, the casting step may include:

[0044] The third slurry preparation step involves adding a plasticizer and / or defoamer to the second slurry and mixing them to obtain a slurry for casting. The slurry obtained in this step is defined as the third slurry. For example, adding a plasticizer and defoamer to the second slurry and mixing them by ball milling at a speed of 50 r / min to 200 r / min for 1 h to 6 h is defined as secondary ball milling.

[0045] In the second casting step, the third slurry is used as the casting slurry and leveled. After drying, a cast film tape is obtained.

[0046] In this application, the formation of microgels by borate ions and PVA can prevent the slurry from delaminating due to gravity during the casting and drying process, thus enabling the preparation of a film with uniform composition.

[0047] Polyvinyl alcohol is a segmental polymer that can be combined with plasticizers to obtain high-quality film tapes with a certain degree of toughness.

[0048] The pressing step involves pressing the film strip together to obtain a preform. The pressing temperature can be 80℃~90℃, and the pressure can be 10MPa~50MPa. The pressing temperature can be slightly higher than the glass transition temperature of PVA.

[0049] The pressing temperature can be set according to the glass transition temperature of the adhesive. In this application, the glass transition temperature of polyvinyl alcohol is 75℃~85℃, which can heat-press different film strips together at a lower temperature to form an integral preform. The film strips are not easy to delaminate, and the preform quality is high.

[0050] The sintering step involves sintering the green body to obtain a ceramic matrix. The sintering temperature is determined based on the powder composition; in this application, the sintering temperature can be between 700℃ and 1000℃.

[0051] In the above embodiments, the available materials for powder, dispersant, water, borate-containing solution, plasticizer and defoamer can refer to the implementation method in Embodiment 2, but this does not limit the material selection of this preparation method. All available materials are within the scope of protection of this application.

[0052] Example 2

[0053] This application provides a water-based cast ceramic slurry for use in the preparation method described in Example 1 to prepare ceramics. The water-based cast ceramic slurry may include powder, dispersant, water, and a borate-containing solution; the powder may include ceramic powder and glass powder. It may also include a pH adjuster and a binder, the binder being a polyvinyl alcohol solution. The pH adjuster may be omitted depending on the pH value of the slurry.

[0054] In some embodiments, the slurry may also include plasticizers and / or defoamers. Plasticizers can improve the rheological properties of ceramic slurries, help improve the ductility of ceramic slurries, making them easier to cast and form the desired shapes and structures, and can also increase the plasticity of ceramic slurries, making them easier to mold, and help maintain the stability of the molded shape.

[0055] Defoamers can effectively remove air bubbles from ceramic slurries, reducing their impact on the molding and sintering process. They can also reduce air bubbles and defects on the surface of ceramic slurries, improve the sintering performance and density of ceramic products, and make the surface quality of the final product smoother and more uniform, thus improving the overall quality of ceramic products.

[0056] In some embodiments, the powder may also include a pore-forming agent. The pore-forming agent can form a microporous structure in the ceramic material, thereby reducing the overall density and increasing the permeability of the ceramic. During sintering, the pore-forming agent can leave pores in the ceramic material, which helps release combustion products and gases, reduces internal pressure during sintering, and is beneficial to the sintering uniformity and stability of the ceramic material. In practice, the pore-forming agent, plasticizer, and defoamer in water-based cast ceramic slurry are synergistic components and are not mixed simultaneously. Generally, they are mixed in two stages, with the plasticizer and defoamer added to the slurry during the second mixing operation.

[0057] In this process, powder, dispersant, water, and a solution containing borate are mixed to obtain a first slurry; then, a pH adjuster is used to adjust the pH value of the first slurry, and the first slurry is stirred and a binder is added in the form of droplets, resulting in a second slurry; plasticizer and defoamer are added to the second slurry, and after mixing, a third slurry is obtained.

[0058] Therefore, in this application, the water-based cast ceramic slurry can be divided into three states according to the order / number / step of component addition, and each state is defined as the first slurry, the second slurry, and the third slurry.

[0059] The first slurry is a mixture of powder, dispersant, solvent and borate solution.

[0060] The second slurry is a slurry mixed with a binder. The first slurry is first pH adjusted and then the binder is added dropwise. The binder is added to the first slurry being stirred by dripping. For details, please refer to the step of adding the binder in Example 1.

[0061] The third slurry is a mixture of plasticizer and defoamer. Both the second and third slurries can be used as slurries for subsequent casting and film formation.

[0062] The following describes the components of the water-based cast ceramic slurry. It should be noted that the embodiments of this application, based on the water-based casting method, involve adding borate ions to the slurry and adding polyvinyl alcohol via droplet addition. This generates microdroplets through a controlled gelation reaction, forming micro-reaction containers between the droplets and the slurry. These containers encapsulate nearby ceramic powder, glass powder, and pore-forming agents (if present). Each droplet forms a microgel with the slurry, achieving the goal of controlling the uniform gelation of the entire system. Furthermore, the droplet-based addition allows for a more complete reaction.

[0063] Therefore, this application does not limit the specific implementation of powder, dispersant, plasticizer or defoamer. The examples in the following embodiments are for further description of this application and do not limit the specific implementation of ceramic preparation method and water-based cast ceramic slurry of this application.

[0064] In some embodiments, the borate-containing solution can be a solution of boric acid, borate, or a mixture of boric acid and borate, such as an aqueous solution of boric acid; the mass concentration of the borate-containing solution can be 1% to 20%, and the amount added can be 1% to 5% of the mass of the powder.

[0065] In Example 1, the influencing factors of the gelation reaction have been described. It can be seen that the concentration and amount of polyvinyl alcohol added should correspond to the concentration and amount of the borate-containing solution. Therefore, in the embodiments of this application, the mass fraction of the polyvinyl alcohol solution can be 5% to 15%, the amount added can be 50% to 150% of the mass of the powder, and its molecular weight can be 1500 to 1700, and the degree of alcoholysis can be 99%.

[0066] In some embodiments, the ceramic powder may include at least one of alumina, silicon dioxide, titanium dioxide, magnesium oxide, quartz powder, and apatite; and / or, the glass powder may include borate glass. By adding borate ions to the slurry and using borate glass powder during sintering, the bonding strength of the ceramic can be improved, and the possibility of cracking can be reduced.

[0067] In some embodiments, the pore-forming agent may include polymethyl methacrylate (PMMA) or carbon fiber.

[0068] In some embodiments, the mass ratio of ceramic powder, glass powder, and pore-forming agent can be 1:0.5:0.1 to 1:0.3:0.5. For example, the mass of the pore-forming agent can be taken as a reference value, and the ratio range can be converted to 10:5:1 to 2:0.6:1.

[0069] In some embodiments, the dispersant may be ammonium styrene, polyvinylpyrrolidone, or polyacrylamide, and the amount added may be 0.5% to 5% of the mass of the powder.

[0070] In some embodiments, the plasticizer may be glycerol, and the amount added may be 5% to 10% of the powder mass.

[0071] In some embodiments, the defoamer may be n-butanol or tributyl phosphate, and the amount added may be 1% to 5% of the powder mass.

[0072] In some embodiments, the water can be pure water or deionized water, and the amount of water added can be 40% to 60% of the mass of the powder.

[0073] The parameters of the components mentioned in the embodiments of this application can be referred to the relevant experimental group in Embodiment 4. The parameter ranges of the above components are preferred embodiments and do not limit the implementation of the water-based cast ceramic slurry provided in this application.

[0074] Example 3

[0075] This application also provides a ceramic, made using the preparation method described in Example 1, and / or made using the water-based cast ceramic slurry described in Example 2. Alternatively, it can be made using the water-based cast ceramic slurry described in Example 2, and the preparation method described in Example 1.

[0076] The ceramic provided in this embodiment has the technical effects of the preparation method / water-based cast ceramic slurry described in the above embodiments, and will not be repeated here.

[0077] Example 4

[0078] This embodiment uses the water-based cast ceramic slurry described in Example 2 and employs the preparation method described in Example 1 to fabricate various ceramics or film tapes for performance testing. Multiple groups of ceramics were fabricated according to the following steps. The control variables can be compared by controlling five parameters: borate ion concentration, solution (slurry) pH value, polyvinyl alcohol concentration, polyvinyl alcohol addition amount, and droplet size.

[0079] Step 1: Take 60g of quartz powder, 30g of low-temperature glass powder (usually referring to glass with an initial melting temperature of 500-800 degrees Celsius), and 10g of PMMA powder. The total mass of the powder is 100g. Add 50g of pure water, 1g of dispersant, and boric acid solution (not added to the control group). Adjust the pH of the slurry with ammonia water. Ball mill and stir for a certain time to obtain water-based casting slurry.

[0080] Step 2: Then add polyvinyl alcohol solution dropwise to the slurry, stirring the slurry at a speed of 150 r / min during the dropwise addition.

[0081] Step 3: Then add glycerol as a plasticizer to the slurry, with an addition amount of 10g, and at the same time, add 1g of n-butanol as a defoamer.

[0082] Step 4: Ball mill the above slurry a second time for 1 hour at a speed of 200 r / min.

[0083] Step 5: Level the obtained slurry on a casting machine and dry it at 60°C for 12 hours to obtain a cast film.

[0084] Step 6: Press the film strip together at 80°C and 10MPa pressure to obtain a raw blank.

[0085] Step 7: Sinter the green body at 700℃ at a heating rate of 1℃ / min for 1 hour to obtain a multilayer porous ceramic matrix.

[0086]

[0087]

[0088] In this diagram, numbers 1-5 represent the PVA solution concentration for comparison, numbers 6-10 represent the PVA addition amount for comparison, numbers 11-15 represent the borate concentration for comparison, numbers 16-20 represent the borate addition amount for comparison, numbers 21-25 represent the PVA droplet size for comparison, and numbers 26-30 represent the slurry pH value for comparison. Number 31 represents the control group without added borate solution.

[0089] The following test methods can be used to test the performance of membrane tapes / ceramics:

[0090] The test methods for tensile deformation and tensile stress of the membrane strip are in accordance with GB / T1040.1-2018 Determination of tensile properties of plastics.

[0091] The ceramic strength test method refers to GB / T 1964-2023 Test Method for Room Temperature Compressive Strength of Porous Ceramics.

[0092] Method for measuring thickness deviation: Use a film thickness measuring instrument to measure the thickness of the film strip at the upper left, lower left, center, upper right, and lower right of the film strip. Take the difference between the maximum and minimum values ​​as the thickness deviation.

[0093] Porosity test method: GB / T 1966 Test method for apparent porosity / volume of porous ceramics.

[0094] Using the above methods, the test data for the above multiple experimental groups are as follows:

[0095]

[0096]

[0097] Referring to the test data from groups 1-30, none of these 30 experiments cracked after sintering, while the control group (group 31), which did not add borate ions, cracked after sintering. Furthermore, in these 30 experimental groups, the tensile fracture deformation and ceramic strength of the membrane strip were both greater than those of the control group.

[0098] The addition of borate ions forms a micro-reaction vessel with PVA, which prevents the ceramic from cracking after sintering and gives the membrane good toughness.

[0099] Referring to the test data of No. 1-5, these five groups of experiments are controlled variable experiments on the concentration of PVA solution. It can be seen that when the concentration is 10% (No. 3 experimental group), the test data shows the highest performance, the largest tensile fracture deformation of the membrane strip, the largest tensile stress of the membrane strip, the smallest thickness deviation, the moderate porosity, the largest ceramic strength, and no cracking after sintering.

[0100] Referring to the test data in groups 6-10, these five groups of experiments are controlled variable experiments on the amount of PVA added. It can be seen that when the amount added is 100g (group 8 of experiments), the test data shows the highest performance, the largest tensile fracture deformation of the film strip, the largest tensile stress of the film strip, the smallest thickness deviation, the moderate porosity, the largest ceramic strength, and no cracking after sintering.

[0101] Referring to the test data of No. 11-15, these five groups of experiments are controlled variable experiments on borate concentration. It can be seen that when the concentration is 10% (experiment group No. 13), the test data shows the highest performance, with the largest tensile fracture deformation of the membrane strip, the largest tensile stress of the membrane strip, the smallest thickness deviation, moderate porosity, the largest ceramic strength, and no cracking after sintering.

[0102] Referring to the test data of No. 16-20, these five groups of experiments are controlled variable experiments on the amount of borate added. It can be seen that when the amount added is 3g (No. 18 experimental group), the test data shows the highest performance, the largest tensile fracture deformation of the membrane strip, the largest tensile stress of the membrane strip, the smallest thickness deviation, the moderate porosity, the largest ceramic strength, and no cracking after sintering.

[0103] Referring to the test data of No. 21-25, these five sets of experiments are controlled variable experiments on the size of PVA droplets. It can be seen that when the droplet size is 500μm (test group No. 23), the test data shows the highest performance, the largest tensile fracture deformation of the membrane strip, the largest tensile stress of the membrane strip, the smallest thickness deviation, the moderate porosity, the largest ceramic strength, and no cracking after sintering.

[0104] Referring to the test data of No. 26-30, these five groups of experiments are controlled variable experiments on the pH value of the slurry. It can be seen that when the pH value is 8.5 (experiment group No. 28), the test data shows the highest performance, the largest tensile fracture deformation of the membrane strip, the largest tensile stress of the membrane strip, the smallest thickness deviation, the moderate porosity, the largest ceramic strength, and no cracking after sintering.

[0105] It should be noted that the above experimental groups and their test data are intended to illustrate the influence of five parameters: borate ion concentration, solution (slurry) pH value, polyvinyl alcohol concentration, polyvinyl alcohol addition amount, and droplet size. These parameters can be adjusted according to the actual ceramic formulation. The above data only correspond to the measurements of the membrane strips and ceramics made from the materials described in steps 1-7 above. The testing of membrane strips and ceramics made from other materials can also refer to the above-mentioned control variable testing method to obtain the optimal composition ratio.

[0106] As can be seen, the comparative experimental group (without added borate ions in the slurry) exhibited cracking after sintering, with low tensile fracture deformation, low tensile stress, and low ceramic strength. The water-based casting slurry and ceramic preparation method provided in this application resulted in ceramics from multiple experimental groups that did not crack, and other properties were improved. In the examples of this application, the cross-linking of PVA and borate ions was used, and the film tape did not crack after hot pressing and sintering, exhibiting good toughness. Both the pore-forming agent and water can volatilize during sintering, forming a porous structure within the ceramic body.

[0107] Among them, groups numbered 3, 8, 13, 18, 23, and 28 represent the groups with better performance in the comparative experiments. The corresponding component parameters can be considered as some preferred implementations, but are not limitations on the parameters of each component in the slurry of this application. Based on these groups with better performance, the cost ratio of each material can be determined and adjusted according to actual needs.

[0108] It should be noted that the experimental comparison in this application was conducted at room temperature. The temperature of the slurry can also be changed by placing it in a constant temperature container (such as a water bath) to promote crosslinking between PVA and borate, or by placing it in an ice bath to slow down the degree of crosslinking.

[0109] This document describes various exemplary embodiments with reference to them. However, those skilled in the art will recognize that changes and modifications can be made to the exemplary embodiments without departing from the scope of this document. For example, various operational steps and components for performing operational steps can be implemented in different ways depending on the specific application or considering any number of cost functions associated with the operation of the system (e.g., one or more steps can be deleted, modified, or combined with other steps).

[0110] While the principles herein have been illustrated in various embodiments, numerous modifications to the structures, arrangements, proportions, elements, materials, and components, particularly suited to specific environments and operational requirements, may be used without departing from the principles and scope of this disclosure. These modifications and other changes or alterations will be included within the scope of this document.

[0111] The foregoing specific descriptions have been described with reference to various embodiments. However, those skilled in the art will recognize that various modifications and changes can be made without departing from the scope of this disclosure. Therefore, considerations for this disclosure are to be illustrative rather than restrictive, and all such modifications are to be included within its scope. Similarly, advantages, other advantages, and solutions to problems with the various embodiments have been described above. However, benefits, advantages, solutions to problems, and any elements that produce these, or make them more explicit, should not be construed as critical, essential, or necessary. The term “comprising” and any other variations thereof as used herein are non-exclusive inclusion, meaning that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not expressly listed or not part of the process, method, system, article, or apparatus. Furthermore, the term “coupled” and any other variations thereof as used herein refer to physical connections, electrical connections, magnetic connections, optical connections, communication connections, functional connections, and / or any other connections.

[0112] Those skilled in the art will recognize that many changes can be made to the details of the above embodiments without departing from the basic principles of the invention. Therefore, the scope of the invention should be determined only by the claims.

Claims

1. A method for preparing water-based cast ceramics, characterized in that, include: A first slurry is obtained by mixing powder, dispersant, water, and a borate-containing solution; the powder includes ceramic powder and glass powder; the mass concentration of the borate-containing solution is 1% to 20%, and the amount added is 1% to 5% of the mass of the powder; A pH adjuster is added to the first slurry to adjust its pH to a preset level; the pH adjuster is an alkaline solution, and the preset pH is 7-10. The first slurry is stirred and a binder is added to the first slurry in the form of droplets to obtain a second slurry. The binder is a polyvinyl alcohol solution, and the droplet size of the binder is controlled to be 10μm~1000μm. The polyvinyl alcohol solution has a mass fraction of 5% to 15%, and the amount added is 50% to 150% of the mass of the powder; the stirring speed is 50 r / min to 150 r / min. The second slurry is used as the slurry for casting and leveled, and then dried to obtain a cast film tape; The cast film strip is pressed together to obtain a raw blank; The green body is sintered to obtain a ceramic matrix.

2. The method as described in claim 1, characterized in that, Leveling the second slurry as a casting slurry includes: Add plasticizer and / or defoamer to the second slurry and mix to obtain the third slurry; The third slurry is used as a slurry for casting and leveling.

3. The method as described in claim 1, characterized in that, The powder also includes a pore-forming agent.

4. The method as described in claim 1, characterized in that, The pressing process is carried out at a temperature of 75℃~85℃.

5. The method as described in claim 1, characterized in that, The sintering temperature is 700℃~1000℃.

6. A ceramic, characterized in that, It is prepared by any one of claims 1-5.

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