A gradient ceramic porous material suitable for direct writing 3D printing and preparation method

Abstract

The present invention provides a gradient ceramic porous material suitable for direct writing 3D printing and a preparation method thereof, comprising hollow microspheres, ceramic powder, flocculant, dispersant, solvent, and the mass percentage of the hollow microspheres and the ceramic powder in the system changes in a gradient, and the sum of the mass percentages of the above components is 100%. The gradient ceramic porous material has a high density. The present invention also provides a preparation method for a gradient ceramic porous material for direct writing 3D printing, wherein the hollow microspheres, ceramic powder, solvent, flocculant, and dispersant are mixed and stirred, and the percentage of the hollow microspheres and the ceramic powder in the system changes in a gradient to obtain a series of gradient ceramic slurries; the series of slurries are added to a 3D printer, and a gradient ceramic blank is obtained by direct writing printing, and a gradient ceramic porous material is obtained after drying, degreasing, and sintering. The method prepares a gradient ceramic porous material by direct writing 3D printing, has a low shrinkage rate, and can control the printing thickness.

Description

Technical Field

[0001] The present invention relates to the technical field of 3D printing, and in particular to a gradient ceramic porous material suitable for direct writing 3D printing and a preparation method thereof. Background Art

[0002] Direct writing technology is a type of 3D printing technology used to prepare three-dimensional functional materials with high aspect ratio and large-span microstructures. As a new type of solid moldless manufacturing technology, compared with photocuring and laser selective sintering methods, it can directly "write" three-dimensional structures at room temperature without the need for ultraviolet light irradiation or laser heating, and the molding process is simple.

[0003] With the development of society, the use environment of materials is becoming more and more complex, and the performance requirements for materials are becoming higher and higher. Traditional materials can no longer meet the needs of modern engineering, and gradient functional materials have emerged. The basic idea of ​​this new material design concept is: according to specific requirements, two materials with different properties are selected, and the internal interface is eliminated by continuously changing the composition and structure of the two materials, so as to obtain a non-homogeneous material whose function gradually changes with the change of composition and structure. Ceramic materials have excellent properties of high strength, high hardness, and high chemical stability, while porous hollow microsphere materials have low density, good thermal insulation, and high catalytic efficiency. Through gradient functional design, their respective excellent properties can be organically combined, which can expand the application of high-performance ceramic porous materials in various fields, and is a key research direction in the field of materials science.

[0004] The existing gradient ceramic preparation technologies mainly include laser sintering and chemical vapor deposition. In the process of melt covering sintering, laser sintering is difficult to solve the major problem of different sintering temperatures of different powders and different sintering shrinkages of different layers. It is still relatively rarely used in the preparation of gradient ceramic porous materials; chemical vapor deposition can produce a smooth and dense structure, which is suitable for the preparation of thin films, but is powerless for the preparation of thicker gradient structures. There is a 3D printing gradient ceramic metal material and preparation method publication number CN113458387A that proposes a method for 3D printing gradient materials to address these problems, but due to the limitations of the manufacturing process, the method provided can only be used to prepare gradient composite materials of small-sized raw materials, and cannot be used for hollow microsphere raw materials with larger particle sizes. Summary of the invention

[0005] The purpose of the present invention is to provide a gradient ceramic porous material and preparation method suitable for direct writing 3D printing, which is used to solve the above-mentioned problems. At the same time, the present invention can prepare gradient materials with complex structures, have low shrinkage, can prepare large-size particle raw materials, and easily control the gradient composition.

[0006] A gradient ceramic porous material suitable for direct writing 3D printing, comprising the following raw materials in weight percentage: 50%-70% hollow microspheres, 10%-30% ceramic powder, 1%-5% flocculant, 0.01%-0.5% dispersant, and solvent, wherein the mass percentages of the hollow microspheres and the ceramic powder in the system vary in a gradient, and the sum of the mass percentages of the above components is 100%.

[0007] The hollow microspheres include one or more of alumina, titanium dioxide, and silicon dioxide, and the particle size of the hollow microspheres is 50-400 μm.

[0008] The ceramic powder includes one or more of porcelain clay, limestone, potassium feldspar and kaolin, and the particle size of the ceramic powder is 5-15 μm.

[0009] The hollow microspheres are made of aluminum oxide, the particle size of the hollow microspheres is 100-300 μm, and the particle size of the ceramic powder is 8-12 μm.

[0010] The flocculant includes one or more of PEG 6000, polyvinyl alcohol and sodium carboxymethyl cellulose.

[0011] The dispersant includes one or more of sodium hexametaphosphate, sodium polyacrylate, and poly (4-styrene sulfonic acid).

[0012] The present invention also includes a method for preparing a gradient ceramic porous material suitable for direct writing 3D printing, comprising the steps of:

[0013] S1: mixing and stirring a solvent, ceramic powder, hollow microspheres, a dispersant, and a flocculant, wherein the percentages of the ceramic powder and the hollow microspheres in the system show a gradient change, thereby obtaining a series of gradient ceramic slurries;

[0014] S2: direct writing molding, adding the series of slurries into the barrel of a 3D printer, and based on a set model, directly writing and extruding through different print heads of the 3D printer, stacking the series of slurries layer by layer to obtain a 3D printed gradient ceramic body;

[0015] S3: drying and sintering the 3D printed gradient ceramic body in sequence to obtain a 3D printed gradient ceramic porous material.

[0016] The direct writing extrusion method is air pressure plus screw extrusion.

[0017] The direct writing molding conditions are: air pressure of 0.3-0.6MPa, printing needle diameter of 1-3mm, printing speed of 3-12mm / s, printing line width of 1.03-3.05mm, and printing layer height of 0.5-2mm.

[0018] The sintering is specifically as follows:

[0019] The sintering temperature was raised from room temperature to 300°C, which took 90 min;

[0020] The sintering temperature was increased from 300°C to 920°C, which took 120 min;

[0021] The sintering temperature was increased from 920°C to 1050°C, which took 90 min;

[0022] The sintering temperature was increased from 1050°C to 1340°C, which took 150 min;

[0023] The sintering temperature is naturally cooled from 1340°C to room temperature to complete the sintering.

[0024] The invention provides a kind of gradient ceramic porous material suitable for direct writing 3D printing and a preparation method thereof, which has the beneficial effects of:

[0025] 1. The 3D printed ceramic gradient porous material provided by the present invention combines large-particle hollow microspheres with small-sized ceramic powders, uses small-sized particles to fill the gaps between large-sized particles, and changes with the gradient of each component to produce a gradient ceramic porous material with stable structure and diverse properties.

[0026] 2. Since the printing raw material solid content of the 3D printing gradient ceramic porous material provided by the present invention is high, the 3D printing ceramic porous material has a lower firing shrinkage rate, and it is easy to control the size of the 3D printed product.

[0027] 3. The 3D printing gradient ceramic porous material extrusion method provided by the present invention is a double extrusion of air pressure and screw, which can more accurately control the delivery of raw materials and has a wider applicability to the rheological properties of raw materials, thus providing more flexible choices in the combination of gradient materials.

[0028] 4. As an additive manufacturing technology, 3D printing direct writing technology has high material utilization, low energy consumption, and is environmentally friendly. It is a green manufacturing technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 This is a schematic diagram of the structure of the 3D printed ceramic gradient porous material in Example 1 of the present invention. DETAILED DESCRIPTION

[0031] The technical solution of the invention is further described below in conjunction with the accompanying drawings and embodiments. The following embodiments are only used to more clearly illustrate the technical solution of the invention and are therefore only used as examples and cannot be used to limit the protection scope of the invention. Example

[0032] 1. Printing slurry preparation

[0033] Hollow microspheres: Alumina, particle size 100-300 μm, mass percentage in the slurry system is 50% and 60%, respectively, made into 2 gradient slurries;

[0034] Ceramic powder: Longquan Baoxi porcelain clay: particle size 8-12μm, mass percentage in the slurry system is 30% and 20% respectively, made into 2 gradient slurries;

[0035] Flocculants: PEG 6000, polyvinyl alcohol, the addition ratio of PEG 6000: polyvinyl alcohol = 3:2, the mass percentages in the slurry system are 1% and 3% respectively;

[0036] Dispersant: sodium hexametaphosphate and sodium polyacrylate, the addition ratio of sodium hexametaphosphate: sodium polyacrylate = 1:1, and the mass percentages in the slurry system are 0.5% and 0.2% respectively;

[0037] Solvent: deionized water, make up the remaining amount of 100% slurry with deionized water.

[0038] The above solvents, dispersants, and flocculants were stirred and mixed into a uniform solution, and ceramic powder and hollow microspheres were slowly added in sequence while stirring. The prepared slurry was placed in a vacuum box to remove bubbles for 2 hours to obtain a high solid content direct writing 3D printing ceramic slurry.

[0039] 2. Printing blank production

[0040] The prepared printing slurries are loaded into the printing barrels respectively, and the blanks are printed according to the set program. The printing parameters are: air pressure of 0.4-0.6MPa, printing needle diameter of 1mm, printing speed of 12mm / s, printing line width of 1.03mm, and printing layer height of 0.5mm. During the printing process, use the 1# print head to print 2mm high slurry A (50% alumina + 30% Longquan Baoxi porcelain clay), and then switch to the 2# print head to print 2mm high slurry B (60% alumina + 20% Longquan Baoxi porcelain clay), and print alternately in turn to obtain a homogeneous gradient blank.

[0041] 3. Sintering

[0042] The green body is sintered according to the following heating curve:

[0043] The sintering temperature was raised from room temperature to 300°C, which took 90 min;

[0044] The sintering temperature was increased from 300°C to 920°C, which took 120 min;

[0045] The sintering temperature was increased from 920°C to 1050°C, which took 90 min;

[0046] The sintering temperature was increased from 1050°C to 1340°C, which took 150 min;

[0047] The sintering temperature is naturally cooled from 1340°C to room temperature to complete the sintering.

[0048] Then the material was cooled naturally and the sintering process was carried out in air, and finally a 3D printed gradient ceramic porous material was obtained, and the shrinkage rate of the material was 5.89%. Example

[0049] 1. Printing slurry preparation

[0050] Hollow microspheres: Alumina, mass percentage in the slurry system: 50%, 55%, 60%, 65%, 70%, made into 5 gradient slurries;

[0051] Ceramic powder: Longquan Baoxi porcelain clay, mass percentage in the slurry system: 30%, 25%, 20%, 15%, 10%, made into 5 gradient slurries;

[0052] Flocculants: PEG 6000, sodium carboxymethyl cellulose, the addition ratio of PEG 6000: sodium carboxymethyl cellulose = 1:1, the mass percentage in the slurry system: 3%, 3.5%, 4%, 4.5%, 5%;

[0053] Dispersant: poly (4-styrene sulfonic acid), mass percentage in the slurry system: 0.01%, 0.01%, 0.02%, 0.03%, 0.05%;

[0054] Solvent: deionized water, make up the remaining amount of 100% slurry with deionized water.

[0055] The above solvents, dispersants, and flocculants were stirred and mixed into a uniform solution, and ceramic powder and hollow microspheres were slowly added in sequence while stirring. The prepared slurry was placed in a vacuum box to remove bubbles for 2 hours to obtain a high solid content direct writing 3D printing ceramic slurry.

[0056] 2. Printing blank production

[0057] The prepared printing slurries are loaded into the printing barrels respectively, and the blanks are printed according to the set program. The printing parameters are: air pressure of 0.4-0.6MPa, printing needle diameter of 3mm, printing speed of 3mm / s, printing line width of 3.05mm, and printing layer height of 2mm. During the printing process, the slurry of 50% alumina + 30% Longquan Baoxi porcelain clay is printed first, and then the alumina content is reduced in turn, and the Longquan Baoxi porcelain clay content is increased in turn. The printing blank with a gradient change in the raw material composition is obtained.

[0058] 3. Sintering

[0059] The green body is sintered according to the following heating curve:

[0060] The sintering temperature was raised from room temperature to 300°C, which took 90 min;

[0061] The sintering temperature was increased from 300°C to 920°C, which took 120 min;

[0062] The sintering temperature was increased from 920°C to 1050°C, which took 90 min;

[0063] The sintering temperature was increased from 1050°C to 1340°C, which took 150 min;

[0064] The sintering temperature is naturally cooled from 1340°C to room temperature to complete the sintering.

[0065] The sintering process is carried out in air, and finally a 3D printed gradient ceramic porous material is obtained, and the shrinkage rate of the material is 5.01%. Example

[0066] 1. Printing slurry preparation

[0067] Hollow microspheres: Alumina and titanium dioxide, the mass ratio of the two is 1:1, the mass percentage in the slurry system is: 60%, 65%, 70%, made into 3 parts of gradient slurry;

[0068] Ceramic powder: Longquan Baoxi porcelain clay and kaolin, the mass ratio of the two is 2:1, the mass percentage in the slurry system is: 20%, 15%, 10%, made into 3 parts of gradient slurry;

[0069] Flocculants: PEG 6000, sodium carboxymethyl cellulose, the addition ratio of PEG 6000: sodium carboxymethyl cellulose = 2:1, the mass percentage in the slurry system: 4%, 4.5%, 5%;

[0070] Dispersant: poly (4-styrene sulfonic acid), mass percentage in the slurry system: 0.02%, 0.03%, 0.05%;

[0071] Solvent: deionized water, make up the remaining amount of 100% slurry with deionized water.

[0072] The above solvents, dispersants, and flocculants are mechanically stirred and mixed into a uniform solution, and ceramic powder and hollow microspheres are slowly added in sequence while stirring. The prepared slurry is placed in a vacuum box to remove bubbles for 2 hours to obtain a high solid content direct writing 3D printing ceramic slurry.

[0073] 2. Printing blank production

[0074] The prepared printing slurries are loaded into the printing barrels respectively, and the blanks are printed according to the set program. The printing parameters are: air pressure of 0.4-0.6MPa, printing needle diameter of 2mm, printing speed of 8mm / s, printing line width of 2.03mm, and printing layer height of 1mm. During the printing process, the slurry of 60% hollow microspheres + 20% ceramic powder is printed first, and then the hollow microsphere content is decreased and the ceramic powder content is increased in sequence, and the printed blanks with gradient changes in raw material composition are obtained.

[0075] 3. Sintering

[0076] The green body is sintered according to the following heating curve:

[0077] The sintering temperature was raised from room temperature to 300°C, which took 90 min;

[0078] The sintering temperature was increased from 300°C to 920°C, which took 120 min;

[0079] The sintering temperature was increased from 920°C to 1050°C, which took 90 min;

[0080] The sintering temperature was increased from 1050°C to 1340°C, which took 150 min;

[0081] The sintering temperature is naturally cooled from 1340°C to room temperature to complete the sintering.

[0082] The sintering process is carried out in air, and finally a 3D printed gradient ceramic porous material is obtained, and the shrinkage rate of the material is 4.27%.

[0083] The specific embodiments described above further illustrate the technical problems, technical solutions and beneficial effects solved by the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for direct writing 3D printing of gradient ceramic porous materials, characterized in that: The raw materials are composed of the following weight percentages: 50%-70% hollow microspheres, 10%-30% ceramic powder, 1%-5% flocculant, 0.01%-0.5% dispersant, and solvent, wherein the mass percentages of the hollow microspheres and the ceramic powder in the system vary in a gradient, and the sum of the mass percentages of the components is 100%; The ceramic powder is porcelain clay; The hollow microspheres are aluminum oxide, the particle size of the hollow microspheres is 100-300 μm, and the particle size of the ceramic powder is 8-12 μm; The flocculant includes one or more of PEG 6000, polyvinyl alcohol, and sodium carboxymethyl cellulose; The dispersant includes one or more of sodium hexametaphosphate, sodium polyacrylate, and poly(4-styrene sulfonic acid); Including preparation method: S1: mixing and stirring a solvent, ceramic powder, hollow microspheres, a dispersant, and a flocculant, wherein the percentages of the ceramic powder and the hollow microspheres in the system show a gradient change, thereby obtaining a series of gradient ceramic slurries; S2: direct writing molding, adding the series of slurries into the barrel of a 3D printer, and based on a set model, directly writing and extruding through different print heads of the 3D printer, stacking the series of slurries layer by layer to obtain a 3D printed gradient ceramic body; S3: drying and sintering the 3D printed gradient ceramic body in sequence to obtain a 3D printed gradient ceramic porous material; The sintering is specifically as follows: The sintering temperature was raised from room temperature to 300°C, which took 90 min; The sintering temperature was increased from 300°C to 920°C, which took 120 min; The sintering temperature was increased from 920°C to 1050°C, which took 90 min; The sintering temperature was increased from 1050°C to 1340°C, which took 150 min; The sintering temperature is naturally cooled from 1340°C to room temperature to complete the sintering.

2. A method for preparing gradient ceramic porous materials suitable for direct writing 3D printing according to claim 1, characterized in that: The direct writing extrusion method is air pressure plus screw extrusion.

3. A method for preparing gradient ceramic porous materials suitable for direct writing 3D printing according to claim 2, characterized in that: The direct writing molding conditions are: air pressure of 0.3-0.6 MPa, printing needle diameter of 1-3 mm, printing speed of 3-12 mm / s, printing line width of 1.03-3.05 mm, and printing layer height of 0.5-2 mm.

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