A method for preparing a multiphase ceramic by using a direct writing 3D printing technology
By using direct-write 3D printing technology, combined with ceramic powder and rheology additives, and controlling the rheological properties of the slurry and the pyrolysis process, the shrinkage and porosity problems in the pyrolysis process of ceramic precursors are solved, achieving efficient molding and excellent performance of multiphase ceramics.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HARBIN INST OF TECH
- Filing Date
- 2023-12-28
- Publication Date
- 2026-06-26
AI Technical Summary
After direct writing printing of existing ceramic precursors, the pyrolysis process from polymer to ceramic results in high linear shrinkage and porosity of the components, leading to a decrease in mechanical properties.
Using direct-write 3D printing technology, ceramic slurry is prepared by weighing ceramic powder, rheology additives and polyborosilicate precursors, and then printed, cured and pyrolyzed under specific conditions. The rheological properties and pyrolysis process of the slurry are controlled to reduce shrinkage and porosity.
It achieves low shrinkage and high yield of multiphase ceramics, with good mechanical and dielectric properties, improved microhardness and flexural strength, and improved molding quality.
Smart Images
Figure CN117697919B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of additive manufacturing of ceramic materials. Background Technology
[0002] In the aerospace and space applications, there is an urgent need for ceramics and ceramic matrix composites that can operate stably in complex and extreme environments. Polymer-converted ceramics, due to their exceptional high-temperature thermal stability, tunable electrical properties, and excellent mechanical properties, possess unique advantages in high-temperature, high-pressure, and oxygen-rich environments, playing a crucial role in sensor components and other applications used in extreme environments. However, traditional molding methods for ceramic materials often rely on molds, significantly limiting the fabrication of high-performance, irregularly shaped ceramic components.
[0003] Direct-write printing technology has become a widely used printing method due to its advantages such as low cost, wide range of adaptable raw materials, fast printing speed, and flexible manufacturing. Compared with photopolymerization printing technology, this method does not require the introduction of numerous additives for complex slurry formulation, thereby further improving ceramic yield. Silicon-based precursor ceramic polymers, due to their good room temperature fluidity and easy cross-linking and curing, are expected to solve problems such as difficulty in forming irregularly shaped ceramic components and low preparation efficiency when combined with direct-write printing technology. However, the forming quality of direct-write printed three-dimensional components is highly dependent on the rheological properties of the printing slurry. Developing slurries with suitable rheological properties (high storage modulus and yield stress) is crucial for direct-write printing. For the printing of ceramic precursors, this in turn depends on the type and content of fillers and the characteristics of additives. Studies have found that direct-write printing of ceramic precursor polymers has a relatively narrow printable window, so formulating slurries suitable for direct-write printing still presents certain difficulties. In addition, the pyrolysis process of the printed preform from polymer to ceramic also presents many challenges, such as high linear shrinkage and porosity of the components, leading to a decrease in mechanical properties. Summary of the Invention
[0004] This invention aims to address the problem that, after direct-write printing of ceramic precursors, the pyrolysis process from polymer to ceramic results in high linear shrinkage and porosity of the components, leading to a decrease in mechanical properties. Therefore, it provides a method for preparing multiphase ceramics using direct-write 3D printing technology.
[0005] A method for preparing multiphase ceramics using direct-write 3D printing technology, comprising the following steps:
[0006] I. Weighing:
[0007] Weigh out 10%–30% ceramic powder, 1%–10% rheology modifiers, and the remainder polyborosilazane PBSZ precursor by mass percentage;
[0008] II. Preparation of ceramic slurry:
[0009] The ceramic powder and rheology additives were added to the polyborosilazane PBSZ precursor in three separate additions. After each addition, the mixture was thoroughly mixed to obtain the ceramic slurry.
[0010] III. 3D Printing:
[0011] The ceramic slurry is transferred into the printing syringe. Before printing, the printing syringe containing the slurry is degassed. Then, direct writing printing is performed at room temperature, with a needle diameter of 0.2 mm to 1 mm, an extrusion pressure of 20 psi to 100 psi, and a printing speed of 2 mm / s to 10 mm / s to obtain a green body of multiphase ceramic.
[0012] IV. Curing and Pyrolysis:
[0013] The method of preparing multiphase ceramics by solidifying and pyrolyzing the green body of multiphase ceramics in sequence is completed by direct writing 3D printing technology.
[0014] The beneficial effects of this invention are:
[0015] 1) The forming quality of direct-write printing (DIW) is highly dependent on the rheological properties of the slurry; therefore, formulating a suitable slurry for DIW printing is particularly important. This invention, without adding additional solvents, utilizes nano-fumed silica and ceramic powder to not only reduce sample shrinkage during pyrolysis but also to regulate the rheological properties of the slurry and avoid the adverse effects of subsequent solvent removal. Figure 4 (a) It can be seen that the apparent viscosity decreases continuously with the increase of shear rate, indicating that the slurry has the characteristics of a shear-thinning non-Newtonian fluid, thus enabling direct writing molding of precursor ceramics with complex shapes at room temperature. Compared with other organic rheology additives, the addition of nano-fumed silica can give the final ceramic component better mechanical and dielectric properties without sacrificing the ceramic yield.
[0016] 2) Compared to the more mature UV-curing printing technology, direct-write printing technology does not require the introduction of numerous organic additives in the slurry preparation stage, thus improving the yield of ceramics. Furthermore, UV-curing printing technology is limited by the penetration of UV light and the complex slurry preparation process, making it unsuitable for resins containing large amounts of opaque fillers.
[0017] 3) By adding inert fillers and controlling the printing and pyrolysis processes, the shrinkage of the precursor ceramics was effectively reduced, further improving its yield and avoiding large macroscopic defects. After pyrolysis, the yield of the precursor multiphase ceramics was approximately 70%, the longitudinal shrinkage rate was approximately 18%, the open porosity was 1.3%, and the elastic modulus after grinding and polishing was 48.79 GPa, the microhardness was 4.27 GPa, and the flexural strength reached 178 MPa.
[0018] 4) The slurry formulation in this invention is simple, the filler cost is low, and the printing operation is simple and flexible. By changing the needle diameter, it is possible to achieve integrated molding of three-dimensional ceramic components with complex shapes, different resolutions, low shrinkage, high ceramic yield, and good mechanical and dielectric properties. Attached Figure Description
[0019] Figure 1 The images are SEM images of the h-BN powder and nano-fumed silica described in step one of Example 1. (a) shows the h-BN powder, and (b) shows the nano-fumed silica.
[0020] Figure 2 The images shown are photographs of the printing process in Example 1 and actual images of the prepared BN / SiBCN multiphase ceramics. (a) and (b) are printing process diagrams of honeycomb and cuboid structures, and (c) and (d) are actual printed images of honeycomb, array, and cuboid structures.
[0021] Figure 3 The XRD pattern of the BN / SiBCN multiphase ceramic prepared in Example 1;
[0022] Figure 4 The apparent viscosity of the ceramic slurry prepared in step two of Example 1 varies with shear rate and modulus varies with shear stress. (a) shows the apparent viscosity as a function of shear rate, and (b) shows the modulus as a function of shear stress.
[0023] Figure 5 The fracture surface SEM images of the BN / SiBCN multiphase ceramic prepared in Example 1 are shown in (a) with a scale bar of 5 μm and (b) with a scale bar of 2 μm.
[0024] Figure 6 The dielectric constant and dielectric loss of the BN / SiBCN composite ceramic prepared in Example 1 are shown in (a) and (b) respectively. Detailed Implementation
[0025] Specific Implementation Method 1: This implementation method is a method for preparing multiphase ceramics using direct-write 3D printing technology, which is carried out according to the following steps:
[0026] I. Weighing:
[0027] Weigh out 10%–30% ceramic powder, 1%–10% rheology modifiers, and the remainder polyborosilazane PBSZ precursor by mass percentage;
[0028] II. Preparation of ceramic slurry:
[0029] The ceramic powder and rheology additives were added to the polyborosilazane PBSZ precursor in three separate additions. After each addition, the mixture was thoroughly mixed to obtain the ceramic slurry.
[0030] III. 3D Printing:
[0031] The ceramic slurry is transferred into the printing syringe. Before printing, the printing syringe containing the slurry is degassed. Then, direct writing printing is performed at room temperature, with a needle diameter of 0.2 mm to 1 mm, an extrusion pressure of 20 psi to 100 psi, and a printing speed of 2 mm / s to 10 mm / s to obtain a green body of multiphase ceramic.
[0032] IV. Curing and Pyrolysis:
[0033] The method of preparing multiphase ceramics by solidifying and pyrolyzing the green body of multiphase ceramics in sequence is completed by direct writing 3D printing technology.
[0034] In this specific embodiment, the extrusion method for direct-write 3D printing is one of pneumatic extrusion, mechanical rod or rotary screw extrusion, or a combination of both.
[0035] In this specific embodiment, the structures printed by direct-write 3D printing include cuboid structures, honeycomb structures, array structures, etc.
[0036] The beneficial effects of this embodiment are:
[0037] 1) The forming quality of direct-write printing is highly dependent on the rheological properties of the slurry; therefore, formulating a slurry suitable for DIW printing is particularly important. In this embodiment, without adding additional solvents, the addition of nano-fumed silica and ceramic powder not only reduces sample shrinkage during pyrolysis but also regulates the rheological properties of the slurry and avoids the adverse effects of subsequent solvent removal. Figure 4 (a) It can be seen that the apparent viscosity decreases continuously with the increase of shear rate, indicating that the slurry has the characteristics of a shear-thinning non-Newtonian fluid, thus enabling direct writing molding of precursor ceramics with complex shapes at room temperature. Compared with other organic rheology additives, the addition of nano-fumed silica can give the final ceramic component better mechanical and dielectric properties without sacrificing the ceramic yield.
[0038] 2) Compared to the more mature UV-curing printing technology, direct-write printing technology does not require the introduction of numerous organic additives in the slurry preparation stage, thus improving the yield of ceramics. Furthermore, UV-curing printing technology is limited by the penetration of UV light and the complex slurry preparation process, making it unsuitable for resins containing large amounts of opaque fillers.
[0039] 3) By adding inert fillers and controlling the printing and pyrolysis processes, the shrinkage of the precursor ceramics was effectively reduced, further improving its yield and avoiding large macroscopic defects. After pyrolysis, the yield of the precursor multiphase ceramics was approximately 70%, the longitudinal shrinkage rate was approximately 18%, the open porosity was 1.3%, and the elastic modulus after grinding and polishing was 48.79 GPa, the microhardness was 4.27 GPa, and the flexural strength reached 178 MPa.
[0040] 4) In this embodiment, the slurry preparation is simple, the filler cost is low, and the printing operation is simple and flexible. By changing the needle diameter, it is possible to achieve the integrated molding of three-dimensional ceramic components with complex shapes, different resolutions, low shrinkage, high ceramic yield, and good mechanical and dielectric properties.
[0041] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the ceramic powder mentioned in step one is BN, Al2O3, or SiO2; the particle size is 1μm to 10μm. Everything else is the same as in Specific Implementation Method One.
[0042] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that the rheology modifier mentioned in step one is nano-sized fumed silica with a particle size of 7nm to 50nm. Everything else is the same as in Specific Implementation Method One or Two.
[0043] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the molecular weight (Mn) of the polyborosilicate PBSZ precursor mentioned in step one is 600–800. Everything else is the same as in Specific Implementation Methods One to Three.
[0044] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that: in step two, the ceramic powder is first added to the polyborosilicate PBSZ precursor in three batches at a mass ratio of 5:3:2, and then the rheology modifier is added to the polyborosilicate PBSZ precursor in three batches at a mass ratio of 5:3:2. Everything else is the same as in Specific Implementation Methods One to Four.
[0045] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that: after each addition of materials in step two, the mixture is thoroughly homogenized. Specifically, a vacuum degassing mixer is used to stir for 10 to 20 minutes at a speed of 1500 to 2500 r / min. Everything else is the same as in Specific Implementation Methods One to Five.
[0046] In this specific embodiment, a vacuum degassing mixer is used for mixing the ceramic slurry, which can simultaneously achieve uniform mixing and degassing of the slurry.
[0047] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that: in step three, the printing syringe containing the slurry undergoes degassing treatment. Specifically, the printing syringe containing the slurry is stirred for 5 to 10 minutes at a rotation speed of 2000 r / min to 2500 r / min. Everything else is the same as in Specific Implementation Methods One to Six.
[0048] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that the curing described in step four is carried out under vacuum, air, or an inert atmosphere at a temperature of 120°C to 180°C for 2 to 5 hours. Everything else is the same as in Specific Implementation Methods One to Seven.
[0049] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that: the pyrolysis described in step four is specifically carried out under vacuum or inert atmosphere, with a heating rate of 0.5℃ / min to 2℃ / min, raising the temperature to 220℃ to 350℃, and holding at 220℃ to 350℃ for 1h to 2h. Then, under vacuum or inert atmosphere, with a heating rate of 0.5℃ / min to 1℃ / min, raising the temperature to 600℃ to 800℃, and holding at 600℃ to 800℃ for 1h to 2h. Then, under vacuum or inert atmosphere, with a heating rate of 1℃ / min to 5℃ / min, raising the temperature to 900℃ to 1600℃, and holding at 900℃ to 1600℃ for 2h to 4h. Finally, with a cooling rate of 1℃ / min to 5℃ / min, the temperature is lowered to 400℃, and then cooled to room temperature in the furnace. The rest is the same as in specific implementation methods one through eight.
[0050] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One to Nine in that the inert atmosphere is nitrogen or argon. Everything else is the same as Specific Implementation Methods One to Nine.
[0051] The beneficial effects of the present invention are verified using the following embodiments:
[0052] Example 1:
[0053] A method for preparing multiphase ceramics using direct-write 3D printing technology, comprising the following steps:
[0054] I. Weighing:
[0055] Weigh out 20% ceramic powder, 5% rheology modifier and the balance polyborosilazane PBSZ precursor by mass percentage;
[0056] II. Preparation of ceramic slurry:
[0057] First, ceramic powder was added to the polyborosilazane PBSZ precursor in three batches at a mass ratio of 5:3:2. Then, rheology additives were added to the polyborosilazane PBSZ precursor in three batches at a mass ratio of 5:3:2. After each addition, the mixture was thoroughly mixed to obtain a ceramic slurry.
[0058] III. 3D Printing:
[0059] The ceramic slurry was transferred into the printing syringe. Before printing, the printing syringe containing the slurry was degassed. Then, direct writing printing was performed at room temperature, with a needle diameter of 0.6 mm, an extrusion pressure of 75 psi, a printing speed of 3.5 mm / s, and a layer height of 0.5 mm to obtain a green body of multiphase ceramic.
[0060] IV. Curing and Pyrolysis:
[0061] The green body of the multiphase ceramic was successively cured and pyrolyzed to obtain BN / SiBCN multiphase ceramic.
[0062] The ceramic powder mentioned in step one is h-BN powder with a particle size of 3μm to 5μm.
[0063] The rheology modifier mentioned in step one is nano-fumed silica with a particle size of about 50 nm.
[0064] The molecular weight (Mn) of the polyborosilicate PBSZ precursor mentioned in step one is 600–800.
[0065] In step two, the ingredients are mixed evenly after each addition. Specifically, a vacuum degassing mixer is used to stir for 10 minutes under normal atmospheric pressure and a speed of 2000 r / min, and then stirred for 5 minutes under vacuum and a speed of 2500 r / min.
[0066] In step three, the printing syringe containing the slurry is degassed. Specifically, the printing syringe containing the slurry is stirred for 5 minutes at a speed of 2500 r / min.
[0067] The green body structures of the multiphase ceramics mentioned in step three are a cuboid structure of 18×6×4mm, a honeycomb structure with a side length of 2×3mm, and an array structure of 20×15mm (length×width).
[0068] The curing process described in step four specifically involves curing for 2 hours under vacuum and at a temperature of 120°C.
[0069] The pyrolysis described in step four is specifically carried out under a nitrogen atmosphere, with the temperature increased to 220°C at a heating rate of 1°C / min, and held at 220°C for 2 hours. Then, under a nitrogen atmosphere, the temperature is increased to 600°C at a heating rate of 0.5°C / min, and held at 600°C for 2 hours. Next, under a nitrogen atmosphere, the temperature is increased to 1000°C at a heating rate of 1°C / min, and held at 1000°C for 2 hours. Finally, the temperature is decreased to 400°C at a cooling rate of 3°C / min, and then cooled to room temperature in the furnace.
[0070] Figure 1 The images show SEM images of the h-BN powder and nano-fumed silica described in step one of Example 1. (a) shows the h-BN powder, and (b) shows the nano-fumed silica. As can be seen from the images, the h-BN sheets are approximately 3–5 μm in size, and the nano-fumed silica particles are approximately 50 nm in size.
[0071] Figure 2 The images show photographs of the printing process in Example 1 and the actual BN / SiBCN composite ceramics prepared. (a) and (b) show the printing process of honeycomb and cuboid structures, while (c) and (d) show the actual printed products of honeycomb, array, and cuboid structures. The cuboid structure is used for subsequent testing of bending strength, density, porosity, and shrinkage. This structure can also be used to evaluate the possibility of printing dense, high-resolution components using direct-write technology. Honeycomb and array structures are also common in the field of direct-write printing. The printing of this structural model is mainly to demonstrate that this composite paste can not only be used for printing conventional shapes but also flexibly for printing complex structures. Figure 2 (cd) It can also be seen that the blank printed by the composite paste has a good shape retention ability.
[0072] Figure 3 The image shows the XRD pattern of the BN / SiBCN multiphase ceramic prepared in Example 1. As can be seen from the figure, sharp BN diffraction peaks appeared in all multiphase ceramics with a solid content of 25 wt% (ceramic powder and rheology additives). Besides the characteristic diffraction peaks of BN, no diffraction peaks of other phases were found. This indicates that the SiBCN ceramic still maintains its amorphous structure at this temperature.
[0073] Figure 4 The figures show the apparent viscosity of the ceramic slurry prepared in step two of Example 1 as a function of shear rate and the modulus as a function of shear stress. (a) shows the apparent viscosity as a function of shear rate, and (b) shows the modulus as a function of shear stress. Figure 4 (a) It can be seen that as the shear rate increases, the viscosity of the slurry continuously decreases, exhibiting obvious shear thinning behavior; from Figure 4(b) It can be seen that when the shear stress is less than the yield stress (4467 Pa), the storage modulus (>10) 4 The storage modulus and loss modulus hardly change with increasing shear stress, and G' > G'", the slurry exhibits solid-like elastic characteristics; when the shear stress is greater than the yield stress, G' < G', viscous deformation begins to dominate the slurry's properties. In summary, the high storage modulus and yield stress of the slurry ensure its good shape retention capability.
[0074] Figure 5 The images show SEM images of the fracture surface of the BN / SiBCN multiphase ceramic prepared in Example 1. (a) Scale bar is 5 μm, and (b) scale bar is 2 μm. As can be seen from the images, h-BN is relatively uniformly distributed in the PDC-SiBCN ceramic matrix, without large-area obvious agglomeration or pores. Furthermore, due to the influence of shear stress during printing, the alignment direction of the BN lamellar structure is almost perpendicular to the entire cross-section. This indicates that during direct-write printing, fillers with a larger aspect ratio are beneficial for forming oriented microstructures under shear stress.
[0075] Figure 6 The dielectric constant and dielectric loss of the BN / SiBCN multiphase ceramic prepared in Example 1 are shown in (a) and (b) respectively. As can be seen from the figure, the dielectric constant is approximately 3.28 and the dielectric loss is as low as approximately 0.01 within the range of 4–6 Hz.
[0076] Step 4: Shrinkage rate of the multiphase ceramic before and after pyrolysis. The BN / SiBCN multiphase ceramic prepared in Example 1 was polished, and then its elastic modulus, microhardness, and flexural strength were tested (test dimensions were 12 mm long × 3.5 mm wide × 2.5 mm high, span was 10 mm, and loading rate was 0.05 mm / min). The relevant data are shown in Table 1 below.
[0077] Table 1. Basic performance data of BN / SiBCN multiphase ceramics prepared in Example 1 (Note: Measurements were taken using a cuboid structure as an example).
[0078]
[0079]
Claims
1. A method for preparing multiphase ceramics using direct-write 3D printing technology, characterized in that... It is done in the following steps: I. Weighing: Weigh out 10%~30% ceramic powder, 1%~10% rheology modifier and the balance polyborosilazane PBSZ precursor by mass percentage; the rheology modifier is nano-fumed silica. II. Preparation of ceramic slurry: The ceramic powder and rheology additives were added to the polyborosilazane PBSZ precursor in three separate additions. After each addition, the mixture was thoroughly mixed to obtain the ceramic slurry. III. 3D Printing: The ceramic slurry is transferred into the printing syringe. Before printing, the printing syringe containing the slurry is degassed. Then, direct writing printing is performed at room temperature, with a needle diameter of 0.2 mm to 1 mm, an extrusion pressure of 20 psi to 100 psi, and a printing speed of 2 mm / s to 10 mm / s to obtain a green body of multiphase ceramic. IV. Curing and Pyrolysis: The method of preparing multiphase ceramics by solidifying and pyrolyzing the green body of multiphase ceramics in sequence is completed by direct writing 3D printing technology.
2. The method for preparing multiphase ceramics using direct-write 3D printing technology according to claim 1, characterized in that... The ceramic powder mentioned in step one is BN, Al2O3 or SiO2; the particle size is 1μm~10μm.
3. The method for preparing multiphase ceramics using direct-write 3D printing technology according to claim 1, characterized in that... The rheology additive mentioned in step one has a particle size of 7nm~50nm.
4. The method for preparing multiphase ceramics using direct-write 3D printing technology according to claim 1, characterized in that... The molecular weight (Mn) of the polyborosilicate PBSZ precursor mentioned in step one is 600-800.
5. A method for preparing multiphase ceramics using direct-write 3D printing technology according to claim 1, characterized in that... In step two, the ceramic powder is first added to the polyborosilicate PBSZ precursor in three batches at a mass ratio of 5:3:2, and then the rheology additive is added to the polyborosilicate PBSZ precursor in three batches at a mass ratio of 5:3:
2.
6. A method for preparing multiphase ceramics using direct-write 3D printing technology according to claim 1, characterized in that... In step two, the ingredients are mixed evenly after each addition. Specifically, a vacuum degassing mixer is used to stir for 10 to 20 minutes at a speed of 1500 r / min to 2500 r / min.
7. A method for preparing multiphase ceramics using direct-write 3D printing technology according to claim 1, characterized in that... In step three, the printing syringe containing the slurry is degassed. Specifically, the printing syringe containing the slurry is stirred for 5 to 10 minutes at a speed of 2000 r / min to 2500 r / min.
8. A method for preparing multiphase ceramics using direct-write 3D printing technology according to claim 1, characterized in that... The curing process described in step four is specifically carried out under vacuum, air, or inert atmosphere conditions and at a temperature of 120℃~180℃ for 2h~5h.
9. A method for preparing multiphase ceramics using direct-write 3D printing technology according to claim 1, characterized in that... The pyrolysis described in step four specifically involves raising the temperature to 220℃~350℃ under vacuum or inert atmosphere at a heating rate of 0.5℃ / min~2℃ / min, and holding it at 220℃~350℃ for 1h~2h. Then, under vacuum or inert atmosphere, the temperature is raised to 600℃~800℃ at a heating rate of 0.5℃ / min~1℃ / min, and held at 600℃~800℃ for 1h~2h. Next, under vacuum or inert atmosphere, the temperature is raised to 900℃~1600℃ at a heating rate of 1℃ / min~5℃ / min, and held at 900℃~1600℃ for 2h~4h. Finally, the temperature is lowered to 400℃ at a cooling rate of 1℃ / min~5℃ / min, and then cooled to room temperature in the furnace.
10. A method for preparing multiphase ceramics using direct-write 3D printing technology according to claim 8 or 9, characterized in that... The inert atmosphere is nitrogen or argon.