阅读说明：本技术 一种基于3d打印的石墨烯/陶瓷有序复合材料制备方法 (3D printing-based preparation method of graphene/ceramic ordered composite material ) 是由 张广明 宋道森 兰红波 蒋进 周欣琪 李惠怡 周雁祥 宋伊凡 于 2021-01-07 设计创作，主要内容包括：本发明公开了一种基于3D打印的石墨烯/陶瓷有序复合材料制备方法,所述打印设备包括数字光处理模块,浆料槽,打印平台,外加电场；所述数字处理模块按照打印的模型分层切片,以光束形式穿过复合透氧膜并投射到浆料上实现固化,随着打印平台沿z轴方向逐渐上移,所述外加电场置于浆料槽内部两侧,实现了石墨烯/陶瓷前驱体复合材料的连续打印,且石墨烯片在辅助电场下有序排列。随后通过烧结步骤实现石墨烯片/陶瓷有序复合材料的制备,可以提高力学性能与电学性能以及增大了材料的抗弯强度和韧性。(The invention discloses a preparation method of a graphene/ceramic ordered composite material based on 3D printing, wherein printing equipment comprises a digital light processing module, a slurry tank, a printing platform and an external electric field; the digital processing module slices according to the printed model in a layered mode, penetrates through the composite oxygen permeable membrane in a light beam mode and projects the composite oxygen permeable membrane onto the slurry to realize solidification, the external electric field is arranged on two sides inside the slurry groove along with the gradual upward movement of the printing platform along the z-axis direction, the continuous printing of the graphene/ceramic precursor composite material is realized, and the graphene sheets are orderly arranged under the auxiliary electric field. And then, the preparation of the graphene sheet/ceramic ordered composite material is realized through a sintering step, so that the mechanical property and the electrical property can be improved, and the bending strength and the toughness of the material are increased.)

1. A preparation method of a graphene/ceramic ordered composite material based on 3D printing is characterized in that printing equipment adopted by the preparation method comprises a digital light processing module, a slurry tank, a printing platform and a high-voltage power supply; the digital processing module penetrates through the composite oxygen permeable membrane in a light beam mode according to the shape of the printing model layered slice and projects the light beam into the slurry. The printing platform gradually moves upwards along the z-axis direction, and the high-voltage power supply is arranged on two sides in the slurry tank and used for increasing an external electric field;

step 1: print model preparation

Firstly, importing a three-dimensional graph into slicing software in an STL file format, and carrying out layered slicing on a model after considering printing duration, material curable thickness and precision requirement factors; then, making the data obtained by slicing into a video file and importing the video file into a digital optical processing module;

step 2: slurry preparation

Mixing a ceramic precursor, methacrylic acid and a photoinitiator according to a certain proportion, then ball-milling and mixing the mixture with graphene, and then carrying out vacuum defoaming to obtain the required composite material slurry;

and step 3: electric field assisted continuous surface exposure 3D printing

Firstly, slowly immersing a printing platform into the slurry until the distance between the printing platform and the composite oxygen-enriched film is slightly larger than the thickness of an uncured area, namely a 'dead area', formed between a forming part and a printing window; then, applying an electric field by using a high-voltage power supply in a specified direction as required; the digital light processing module projects the prepared video image onto the slurry, the printing platform rises at a certain speed, at the moment, the formed part cured after being irradiated by ultraviolet light continuously rises along with the rise of the printing platform, a gap left by the rising of the formed part is also rapidly filled by the surrounding slurry, and the whole process is in a continuous state all the time; and finally, when the video playing is finished, the composite material formed part carrying the orderly arranged graphene is completely dragged out of the slurry.

And 4, step 4: post-printing processing

And sintering the printed structure.

2. The preparation method of the graphene/ceramic ordered composite material based on 3D printing according to claim 1, wherein the digital light processing module projects light with a wavelength of 405nm and a maximum power of 800 mW.

3. The preparation method of the graphene/ceramic ordered composite material based on 3D printing as claimed in claim 1, wherein the composite oxygen permeable membrane comprises a support layer and a low surface energy layer, the support layer is located at the lower part of the low surface layer, the support layer is a microporous PET membrane to ensure support strength and certain oxygen permeability, the low surface energy layer is PDMS to prevent adhesion, and the filling of slurry is ensured to cure the ceramic precursor material.

4. The preparation method of the graphene/ceramic ordered composite material based on 3D printing according to claim 1, wherein the composite oxygen permeable membrane is PDMS/SiO₂Film of said PDMS/SiO₂Etching SiO off the film with hydrofluoric acid solution on the upper layer₂The PDMS membrane of (1); the lower layer is non-etched SiO₂PDMS/SiO₂And (3) a membrane.

5. The preparation method of the graphene/ceramic ordered composite material based on 3D printing according to claim 5,

the PDMS/SiO₂The preparation method of the membrane comprises the following steps:

firstly, spherical SiO with the grain diameter of about 200nm is taken₂Premixing the particles with Dow Corning PDMS solution, SiO₂The mass percentage is 10-40%, and the mixture is stirred for 2-5min at 200r/min-300 r/min;

secondly, putting the mixed solution into an ultrasonic cleaning machine to be mixed for 15-20 min;

thirdly, adding a PDMS curing agent after standing and cooling, wherein the mass ratio of the curing agent to the PDMS premix is 1/10-1/8, and stirring at 200r/min-300r/min for 3-5 min;

standing for 12-24h at the temperature of 0-8 ℃ until no bubbles exist;

utilizing a numerical control engraving machine to print the mixed solution into a film by heating a bottom plate at the temperature of 80-100 ℃, air pressure of 30-50Kpa and 320-400 km/h;

sixthly, drying the printed film in a drying box;

seventhly, completely solidifying the SiO₂Immersion of PDMS Mixed films in SiO-filled₂In a container for the suspension of SiO₂The grain diameter is 2-5 mu m, and the mixture is vertically pulled upwards at a constant speed of 1-8mm/s by a pulling machine;

eighthly, heating the composite membrane for 60-80h at the temperature of 200-250 ℃;

ninthly, spin-coating the SU-8 epoxy resin on the SiO on the surface of the composite film by a spin coater₂In the gap, the rotating speed is 2500-;

curing the photoresist on the surface of the capacitor body by using an ultraviolet curing lamp for 1-3 min;

etching the composite film in hydrofluoric acid solution for 5-15min to remove SiO on the surface₂Thoroughly cleaning with alcohol, and drying in a drying oven.

The final composite transparent film has thickness of 50-100 μm, oxygen transmission efficiency over 50barrer, ultraviolet transmittance not lower than 80%, and strength not lower than 20 kPa.

6. The preparation method of the graphene/ceramic ordered composite material based on 3D printing according to claim 1, wherein the ceramic precursor is mixed with graphene, preferably by ball milling, and the ball milling parameters are rotation speed: 300-500 r/min; time: pausing for 10min to 12h, preferably every 1 h; the time for vacuum debubbling is preferably 2 h.

7. The preparation method of the graphene/ceramic ordered composite material based on 3D printing according to claim 1, wherein the graphene is added to the ordered composite material in a mass fraction of 0.1% to 5%.

8. The preparation method of the graphene/ceramic ordered composite material based on 3D printing as claimed in claim 1, wherein a high voltage power supply is used to apply a DC electric field, a DC constant voltage power supply is used to 500V/cm, and the graphene sheets in the material are arranged on the microscopic tissue layer in a non-contact mode.

9. The preparation method of the 3D printing-based graphene/ceramic ordered composite material, according to claim 1, is characterized in that the graphene sheet uses industrial-grade MLG powder, the diameter of the sheet layer is 10-50 μm, the thickness of the sheet layer is 3.4-7 nm, and the graphene sheet serves as a reinforcement to enhance the conductivity and the bending strength of the material.

10. The preparation method of the graphene/ceramic ordered composite material based on 3D printing according to claims 1 to 9, wherein the precursor is preferably zirconium n-propoxide or polycarbosilazane.

Technical Field

The invention relates to the field of 3D printing, in particular to a preparation method of a graphene/ceramic ordered composite material based on 3D printing.

Background

The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

The ceramic material has the outstanding advantages of high strength, high hardness, high temperature resistance, oxidation resistance, corrosion resistance, stable chemical performance, light weight (low density) and the like, and is widely applied to the fields of aerospace, biomedical treatment, automobiles, electricity, energy sources, national defense and the like. However, the ceramic material always faces the problem of poor toughness, which restricts the wider application of the ceramic parts.

Graphene has been widely paid attention to academia and industry due to its excellent optical properties, mechanical properties and heat and electrical conductivity as a two-dimensional nano material. Graphene is widely applied to various composite materials as an additive, but the existing traditional forming and general 3D printing methods cannot obtain the composite material with uniformly distributed graphene according to a certain rule due to process limitation, so that the performance of graphene is greatly reduced in the material, and the application and popularity of the graphene/polymer composite material are limited.

For graphene/ceramic composite materials, the conventional processes such as compression molding are mainly relied on at present. Compared with the traditional ceramic composite material forming process, the 3D printing technology has the following remarkable advantages: (1) the method has the advantages of no need of a blank and a die, short production period and low manufacturing cost; (2) the manufacturing precision is high; (3) the forming of complex structures with almost any shape can be realized, and the constraint of manufacturing geometric shapes by the traditional process is broken through; (4) the method is suitable for individual customization and small-batch production of single pieces; (5) the molding materials are wide in types, such as zirconia, alumina, tri-calcium phosphate, silicon carbide, titanium carbo-silicide, ceramic precursors, ceramic matrix composites and the like. In addition, the method has unique advantages in the aspects of micro part 3D printing, ceramic/metal composite materials and functional gradient materials, and material-structure-function integrated printing.

In order to further improve the performance of the graphene/ceramic composite material, the application provides a preparation method of the graphene/ceramic ordered composite material based on 3D printing.

Disclosure of Invention

In order to realize the purpose of the invention, the invention is realized by adopting the following technical scheme:

a preparation method of a graphene/ceramic ordered composite material based on 3D printing is disclosed, wherein printing equipment comprises a digital light processing module, a slurry tank, a printing platform and a high-voltage power supply; the digital processing module is in a layered slice shape according to the printing model, penetrates through the composite oxygen permeable membrane in a light beam mode and projects into the slurry. The printing platform gradually moves upwards along the z-axis direction, and the high-voltage power supply is arranged on two sides in the slurry tank and used for increasing an external electric field;

step 1: print model preparation

Firstly, importing a three-dimensional graph into slicing software in an STL file format, and carrying out layered slicing on a model after considering printing duration, material curable thickness and precision requirement factors; then making the data obtained by slicing into a video file and importing the video file into a digital optical processing module;

step 2: slurry preparation

Mixing a ceramic precursor, methacrylic acid and a photoinitiator according to a certain proportion, then ball-milling and mixing the mixture with graphene, and then carrying out vacuum defoaming to obtain the required composite material slurry;

and step 3: electric field assisted continuous surface exposure 3D printing

Firstly, slowly immersing a printing platform into the slurry until the distance between the printing platform and the composite oxygen-enriched film is slightly larger than the thickness of an uncured area, namely a dead area, formed between a formed part and a printing window; then, applying an electric field by using a high-voltage power supply in a specified direction as required; the digital light processing module projects the prepared video image onto the slurry, the printing platform rises at a certain speed, at the moment, the formed part cured after being irradiated by ultraviolet light continuously rises along with the rising of the printing platform, a gap left by the rising of the formed part is also rapidly filled by the surrounding slurry, and the whole process is in a continuous state all the time; and finally, when the video playing is finished, the composite material formed part carrying the orderly-arranged graphene is completely dragged out from the slurry.

And 4, step 4: post-printing processing

And sintering the printed structure.

In some embodiments of the present application, the sintering process is performed in a tube furnace or a box furnace under an inert gas blanket.

In some embodiments of the present application, the composite oxygen permeable membrane comprises a support layer and a low surface energy layer, the support layer is located at the lower part of the low surface layer, the support layer is made of a microporous PET film to ensure support strength and certain oxygen permeability, the low surface energy layer is made of PDMS to prevent adhesion, and filling of slurry is ensured to cure the ceramic precursor material.

In some embodiments of the present application, the digital light processing module projects light with a wavelength of 405nm and a maximum power of 800 mW.

In some embodiments of the present application, the composite oxygen permeable membrane is PDMS/SiO₂Film of said PDMS/SiO₂Etching SiO off the film with hydrofluoric acid solution on the upper layer₂The PDMS membrane of (1); the lower layer is non-etched SiO₂PDMS/SiO₂And (3) a membrane.

In some embodiments of the present application, the PDMS/SiO₂The preparation method of the membrane comprises the following steps:

firstly, spherical SiO with the grain diameter of about 200nm is taken₂Premixing the particles with Dow Corning PDMS solution, SiO₂The mass percentage is 10-40%, and the ratio is 200r/min-300r/min stirring for 2-5 min;

secondly, putting the mixed solution into an ultrasonic cleaning machine to be mixed for 15-20 min;

thirdly, adding a PDMS curing agent after standing and cooling, wherein the mass ratio of the curing agent to the PDMS premix is 1/10-1/8, and stirring at 200r/min-300r/min for 3-5 min;

standing for 12-24h at the temperature of 0-8 ℃ until no bubbles exist;

utilizing a numerical control engraving machine to print the mixed solution into a film by heating a bottom plate at the temperature of 80-100 ℃, air pressure of 30-50Kpa and 320-400 km/h;

sixthly, drying the printed film in a drying box;

seventhly, completely solidifying the SiO₂Immersion of PDMS Mixed films in SiO-filled₂In a container for the suspension of SiO₂The grain diameter is 2-5 mu m, and the mixture is vertically pulled upwards at a constant speed of 1-8mm/s by a pulling machine;

eighthly, heating the composite membrane for 60-80h at the temperature of 200-250 ℃;

ninthly, spin-coating the SU-8 epoxy resin on the SiO on the surface of the composite film by a spin coater₂In the gap, the rotation speed is 2500-;

curing the photoresist on the surface of the capacitor body by using an ultraviolet curing lamp for 1-3 min;

etching the composite film in hydrofluoric acid solution for 5-15min to remove SiO on the surface₂Thoroughly cleaning with alcohol, and drying in a drying oven.

The final composite transparent film has thickness of 50-100 μm, oxygen transmission efficiency above 50barrer, ultraviolet transmittance not lower than 80%, and strength not lower than 20 kPa.

In some embodiments of the present application, the ceramic precursor is mixed with graphene, preferably by ball milling, and the ball milling parameters are: 300-500 r/min; time: pause for 10-12h, preferably every 1h for 10 min.

In some embodiments of the present application, the time for vacuum debubbling is 2 hours.

In some embodiments of the present application, the added mass fraction of graphene in the ordered composite is 0.1% to 5%.

In some embodiments of the present application, the printing speed is 10mm/h to 100mm/h

In some embodiments of the present application, a dc constant voltage power supply of 500V/cm is used to apply a dc electric field using a high voltage power supply to provide a contactless adjustment of the alignment of graphene sheets in the material across the microscopic tissue layers.

In some embodiments of the present application, the graphene sheet uses industrial MLG powder, the diameter of the sheet layer is 10-50 μm, and the thickness of the sheet layer is 3.4-7 nm, and the graphene sheet serves as a reinforcement to enhance the conductivity and the bending strength of the material.

In some embodiments of the present application, the ceramic precursor may be of the existing class of ceramic precursors suitable for 3D printing, preferably zirconium n-propoxide or polycarbosilazane.

In some embodiments of the present application, in order to ensure that no bubble exists between the printing platform and the slurry, the slurry can be placed in multiple ways, preferably, the slurry is placed in a side position to effectively ensure the discharge of gas, or the slurry is used to wet the printing platform in advance, so as to achieve better attachment of the slurry and the printing platform.

In some embodiments of the present application, the printing apparatus further comprises a control module for controlling the printing program according to the set printing data.

Compared with the prior art, the beneficial effect of this disclosure is:

1. 3D printing of the ceramic/graphene composite material is realized for the first time by combining the ceramic precursor with the graphene;

2. the graphene sheets are guided to be directionally arranged by the aid of an electric field, so that the bending strength and the fracture toughness of the ceramic are obviously enhanced.

3. The problem of serious layering in discontinuous ceramic printing is solved, and meanwhile, the surface can be infinitely fine and smooth.

4. By optimizing and selecting the composite oxygen permeable membraneThe printing precision is improved by selecting the composite oxygen permeable film as PDMS/SiO₂Film, innovatively prepared from SiO₂The oxygen enrichment performance of the original PDMS membrane is improved without reducing the light transmittance of the PDMS membrane, the mechanical property of the original PDMS membrane can be improved, and a large-volume product can be printed by matching with a large printing window; the thickness of a dead zone generated during printing can be regulated and controlled within a certain range, and finally a certain effect can be generated on matching the viscosity of printing slurry; the aging speed of the composite film is reduced, the cost is reduced, the efficiency is improved, and sufficient oxygen can be provided for printing; the hydrophobic layer on the composite film enables the fluidity of the slurry on the composite film to be enhanced, namely the slurry filling speed in the printing process is increased.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a schematic view of a printing apparatus in an embodiment of the present application;

FIG. 2 is a drawing of an experimental apparatus for printing graphene/ceramic ordered composite material based on 3D printing in the embodiment of the present application;

fig. 3 is a schematic view of graphene arrangement of the present application;

FIG. 4 is PDMS/SiO of the present application₂Schematic of the structure of the membrane.

Wherein, 1, a printing platform; 2. a slurry tank; 3. a composite oxygen-enriched membrane; 4. a digital light processing module; 5. A dead zone; 6. an electrode sheet; 7. sizing agent; 8. a forming member; 9. etching away SiO₂The PDMS membrane of (1);

10. non-etched SiO₂PDMS/SiO₂A film; 11. a control module; 12. a high voltage power supply.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments.

The method for printing the graphene/ceramic ordered composite material through electric field assisted continuous surface exposure 3D combines the characteristics that the surface appearance of a formed part can be improved through continuous surface exposure 3D printing and the characteristics that an auxiliary electric field is applied to control the conductive nano material to obtain the ordered composite material.

In the printing process, oxygen molecules in the air can penetrate through the composite oxygen-enriched film to enter the slurry in the slurry tank, and the oxygen content is smaller and smaller along with the distance from the composite oxygen-enriched film; at the moment, when the slurry close to the composite oxygen-enriched film absorbs external light energy, the slurry in the area can not be solidified due to high oxygen content, the area is called as a dead zone, the formed part and the composite oxygen-enriched film can not be adhered due to the existence of the dead zone, and therefore stripping operation is not needed during printing, continuous printing is really achieved, and theoretically, the surface precision of the formed part can reach infinite fineness.

The inventor utilizes the stronger dielectric property of graphene, under the action of an electric field, the graphene generates a polarization reaction, and graphene sheets originally randomly distributed in a precursor matrix can show an ordered arrangement mode, namely the arrangement direction is parallel to the direction of the electric field. After polarization, graphene can be regarded as an electric dipole, and at the moment, electric field force acting on positive and negative charges at two ends of graphene can form a couple, and the couple moment M is

M＝qELsinθ (1)

In the formula, M is moment of couple, q is charges at two ends of the polarized graphene, E is applied electric field intensity, L is the length of the graphene, and theta is an included angle between the axial direction of the graphene and the direction of the electric field. Because the two-dimensional graphene has shape anisotropy, the polarization moment parallel to the graphene is far larger than the polarization moment perpendicular to the graphene, and the difference can cause the graphene to generate directional torsion force in the direction of an electric field, so that the graphene rotates, and finally the graphene is shown to be in ordered arrangement parallel to the direction of the electric field under the induction of the electric field.

Example 1

A preparation method of a graphene/ceramic ordered composite material based on 3D printing comprises the following steps:

step 1: print model preparation

Firstly, importing a three-dimensional graph into slicing software in an STL file format, and carrying out layered slicing on a model after considering printing duration, material curable thickness and precision requirement factors; then making the data obtained by slicing into a video file and importing the video file into a digital optical processing module;

step 2: material slurry preparation

Mixing zirconium n-propoxide and methacrylic acid according to a ratio of 2:1, adding 1 wt.% of photoinitiator, preparing a formed ceramic precursor solution, and performing ball milling mixing with graphene according to a mass fraction ratio of 99:1, wherein the ball milling parameters are rotation speeds: 500 r/min; time: pausing for 10min every 1h for 12h, and then carrying out vacuum defoaming for 2h to obtain the required composite material slurry;

the viscosity of the precursor composite material is 280mPs, the graphene sheet is made of industrial-grade MLG powder, the diameter of the sheet layer is 10-50 mu m, and the thickness of the sheet layer is 3.4-7 nm.

And step 3: electric field assisted continuous surface exposure 3D printing

Firstly, slowly immersing a printing platform into the slurry until the distance between the printing platform and the composite oxygen-enriched film is slightly larger than the thickness of an uncured area, namely a dead area, formed between a formed part and a printing window;

the composite oxygen permeable membrane comprises a supporting layer and a low surface energy layer, wherein the supporting layer is positioned at the lower part of the low surface layer, the supporting layer is a microporous PET membrane, and the low surface energy layer is PDMS;

then, a direct current electric field is applied by using a high-voltage power supply in a specified direction as required, and the direct current constant voltage power supply is 800V/cm; then, the digital light processing module projects the prepared video image onto the slurry, and simultaneously, the printing platform rises at a certain speed, the wavelength of the light projected by the digital light processing module is 405nm, and the maximum power of the light source is 800 mW; at the moment, the formed part solidified after being irradiated by ultraviolet light continuously rises along with the rising of the printing platform, a gap left by the rising of the formed part is also quickly filled by the surrounding slurry, and the whole process is in a continuous state all the time; and finally, when the video playing is finished, the composite material formed part carrying the orderly arranged graphene is completely dragged out from the slurry.

And 4, step 4: post-printing processing

And after printing is finished, taking down and cleaning the formed part and then sintering.

The whole sintering process is carried out in a tubular furnace, high-purity Ar gas is adopted for protection, the temperature is heated to 600 ℃ at the speed of 1 ℃/min and is kept for 1h, then the temperature is heated to 1200 ℃ at the speed of 5 ℃/min and is kept for 2h, and then sintering is carried out by naturally cooling the sintering parameters, so that the graphene/ZrOC ordered composite material is obtained.

Example 2

In contrast to example 1, the composite oxygen permeable membrane was made of PDMS/SiO₂Is composed of (a) wherein

The upper layer is a PDMS film with the etched surface and the thickness of 10 mu m; the lower layer is PDMS/SiO₂The composite film has a thickness of 50 μm.

The adopted precursor is formed by mixing polycarbosilazane and methacrylic acid according to the ratio of 2:1, and adding 1 wt.% of photoinitiator to prepare a formed ceramic precursor solution;

and after printing is finished, taking down and cleaning the formed part and then sintering. The whole sintering process is carried out in a tubular furnace, high-purity Ar gas is adopted for protection, the temperature is heated to 600 ℃ at the speed of 1 ℃/min and is kept for 1h, then the temperature is heated to 1500 ℃ at the speed of 10 ℃/min and is kept for 2h, and then sintering is carried out by naturally cooling the sintering parameters, so that the graphene/SiCN ceramic coating is obtained.

Test results show that examples 1 and 2 both achieve continuous ordered preparation of graphene/ceramic ordered composites; through tests, the graphene/ceramic ordered composite material with the content of 2 wt% is obviously superior to the disordered composite material in bending strength, and the toughness and strength of the ceramic are obviously improved.

The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the technical solutions described in the foregoing embodiments, or some of the technical features may be substituted equally; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions.