High-toughness high-entropy ceramic photocuring slurry and preparation method thereof

Abstract

The invention belongs to the technical field of photocuring 3D printing materials, and particularly relates to high-toughness and high-entropy ceramic photocuring slurry and a preparation method thereof.The preparation method comprises the steps that perfluoropolyether and nano zeolite powder are stirred and mixed for 1-3 hours at the temperature of 90-110 DEG C, and a first mixture is obtained; and adding polytetrafluoroethylene powder with a specific particle size ratio into the first mixture, continuously stirring and mixing at 200-220 DEG C for 1-3 hours, and cooling to obtain a second mixture, namely the anti-settling reinforcing agent, high-entropy ceramic powder is formed; compounding the slurry: adding a surface modifier, a photoinitiator and a toughness-enhanced nanophase into the anti-sedimentation enhancer obtained in the step 1, mixing, and ball-milling for 8-16 hours to obtain the high-toughness and high-entropy ceramic photocuring slurry, forming a stable three-dimensional network structure in the slurry, and preparing the high-toughness and high-entropy ceramic photocuring slurry by utilizing a steric hindrance effect and a lubricating effect. The sedimentation tendency of the high-density, multi-component and high-entropy ceramic powder is greatly inhibited, and the slurry does not cake after standing for 30 days.

Description

Technical Field

[0001] This invention belongs to the field of photopolymerization 3D printing materials technology, specifically relating to a ceramic slurry with high toughness and high entropy effect suitable for stereolithography (SLA) technology and its preparation method. Background Technology

[0002] Photopolymer 3D printing technology has shown great potential in fabricating complex ceramic components due to its high precision. However, traditional photopolymer ceramic slurries face two major technical bottlenecks: First, to meet the requirements of densification and mechanical strength in the final ceramic part, a high solids content (usually >40 vol%) is required. However, this often leads to a sharp increase in slurry viscosity and poor fluidity, affecting material spreading, leveling, and printing accuracy during the printing process. Furthermore, prolonged static storage can easily cause ceramic particles to settle and agglomerate, resulting in poor storage stability. Second, although sintered bodies of conventional single or binary ceramic systems (such as alumina and zirconium oxide) have high hardness, they are inherently brittle and lack toughness. They are prone to catastrophic fracture under impact or stress, limiting their application in harsh working conditions.

[0003] High-entropy ceramics are a relatively new concept developed in recent years. They consist of four or more metal cations in equimolar or near-equimolar ratios and possess a unique "high-entropy effect," which can significantly improve the strength, hardness, corrosion resistance, and high-temperature stability of ceramic materials. However, introducing the concept of high-entropy ceramics into photopolymerization 3D printing faces significant challenges: the density, particle size, and surface properties of various ceramic powders differ greatly, making it extremely difficult to achieve uniform dispersion and stable suspension of the slurry, and leading to easy phase separation and sedimentation; at the same time, the solid-phase reaction kinetics of multi-component powders during sintering are complex, placing higher demands on the removal of organic matter from the slurry and the densification process during sintering.

[0004] Existing technologies typically improve slurry stability by adding dispersants or modifying the surface of ceramic powders, but the effects are limited and may introduce impurities that affect sintering. Therefore, developing a photocurable ceramic slurry that can simultaneously solve the problems of high viscosity due to high solid content, sedimentation caused by multi-component powders, and ultimately obtain a high-toughness sintered body has become a pressing technical challenge in this field. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the primary objective of this invention is to provide a method for preparing high-toughness, high-entropy ceramic photocurable slurry. This method effectively solves the problem of dispersion stability of high-entropy ceramic powder in the slurry through innovative slurry component design and unique pretreatment process, and significantly improves the toughness of the final ceramic part.

[0006] Another objective of this invention is to provide a photocurable ceramic slurry prepared by the above method, which has moderate viscosity, excellent storage stability, high green strength after curing, and excellent comprehensive properties of high-entropy ceramics after sintering, especially outstanding fracture toughness.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing a high-toughness, high-entropy ceramic photocurable slurry, comprising the following steps: Preparation of anti-settling reinforcing agent: Perfluoropolyether and nano zeolite powder are stirred and mixed at 90-110℃ for 1-3 hours to obtain a first mixture; polytetrafluoroethylene powder with a specific particle size ratio is added to the first mixture, and stirring and mixing are continued at 200-220℃ for 1-3 hours. After cooling, a second mixture is obtained, which is the anti-settling reinforcing agent. Pretreatment of high-entropy ceramic powder: Mechanical alloying is performed on at least four metal oxide ceramic powders in equimolar ratios (the metals are selected from four or five of Zr, Hf, Ti, Ta, Nb, Cr, Mo, W) to form high-entropy ceramic powder; Slurry compounding: The anti-settling reinforcing agent obtained in step 1, the high-entropy ceramic precursor powder obtained in step 2, the prepolymer, and the active diluent are initially mixed and ball-milled to obtain a premixed liquid; Final slurry preparation: Surface modifier, photoinitiator and toughening-enhancing nanophase are added to the premixed liquid, and after mixing, the mixture is ball-milled for 8-16 hours to obtain the high-toughness high-entropy ceramic photocurable slurry.

[0008] Preferably, the mass ratio of the perfluoropolyether, nano-zeolite powder, and polytetrafluoroethylene powder is (10-15):3:5. The polytetrafluoroethylene powder is composed of PTFE powder with a particle size of 1-3 μm and PTFE powder with a particle size of 0.1-0.5 μm in a mass ratio of 1:3.

[0009] Preferably, the toughness-enhancing nanophase is at least one of carbon nanotubes, graphene nanosheets, or zirconium oxide nanowires modified with a silane coupling agent, and its addition amount is 0.5%-3% of the total mass of the ceramic powder.

[0010] Preferably, the components are as follows by mass: 50-70 parts of high-entropy ceramic powder, 10-30 parts of prepolymer, 10-30 parts of reactive diluent, 3-7 parts of anti-settling reinforcing agent, 2-6 parts of surface modifier, 1-4 parts of photoinitiator, and 0.5-3 parts of toughening-enhancing nanophase.

[0011] Preferably, the prepolymer is either polyurethane acrylate or epoxy acrylate.

[0012] Preferably, the reactive diluent is one of β-hydroxyethyl methacrylate or 1,6-hexanediol diacrylate.

[0013] Secondly, the present invention provides a high-toughness, high-entropy ceramic photocurable slurry prepared by the above-described preparation method.

[0014] Beneficial effects: Compared with the prior art, the outstanding advantages of the present invention are: This invention's unique "anti-settling reinforcing agent" utilizes the synergistic effect of perfluoropolyether and multi-scale PTFE / zeolite at high temperatures to form a stable three-dimensional network structure within the slurry. By leveraging steric hindrance and lubrication, it significantly suppresses the settling tendency of high-density, multi-component, high-entropy ceramic powders, resulting in no clumping of the slurry after 30 days of standing. Simultaneously, the slurry viscosity is controlled at 2.0-3.0 Pa·s (@30s). -1 Within the ideal range, it has good fluidity and is very suitable for scraper spreading and liquid leveling in SLA equipment.

[0015] This invention creatively introduces "toughness-enhancing nanophases" (such as carbon nanotubes and graphene) and combines them with a high-entropy ceramic system. During sintering, these nanophases can bridge cracks, induce crack deflection and bifurcation, and effectively dissipate fracture energy, thereby significantly overcoming the intrinsic brittleness of ceramic materials. The resulting high-entropy ceramic parts exhibit a fracture toughness (KIC) as high as 8.0 MPa·m. 1 / 2 The above are far superior to traditional structural ceramics.

[0016] High-entropy ceramics inherently exhibit severe lattice distortion and a high number of grain boundaries, which already hinder crack propagation to some extent. This invention combines the multi-principal-element solid solution structure of high-entropy ceramics with the toughening mechanism of nano-reinforcing phases, generating a synergistic effect of "1+1>2," achieving a leap in toughness while maintaining high hardness, high strength, and high-entropy properties.

[0017] The preparation method of this invention has clear steps, the required raw materials are readily available, and the pretreatment and composite ball milling are routine operations in the field of materials science. It is easy to scale up production and has good industrialization prospects. Detailed Implementation

[0018] The present invention will be described in detail below through examples, but the invention is not limited thereto. Unless otherwise specified, all raw materials used are industrial grade.

[0019] Example 1 Preparation of anti-settling reinforcing agent: Weigh 12.5g of perfluoropolyether and 3g of nano-zeolite with a particle size of 0.3μm, and stir at 100℃ for 2 hours. Add 5g of mixed powder consisting of 1.25g of polytetrafluoroethylene with a particle size of 2μm and 3.75g of polytetrafluoroethylene with a particle size of 0.3μm, heat to 210℃ and stir for 2 hours. After cooling, the anti-settling reinforcing agent is obtained.

[0020] High-entropy ceramic powder pretreatment: Weigh 100g each of ZrO2, HfO2, TiO2, and Ta2O5 powders (D50=0.5μm) in equimolar ratio, place them in a planetary ball mill and dry mix for 4 hours to obtain high-entropy ceramic powder.

[0021] Slurry compounding: Take 60 parts of the mixed powder from step 2, 20 parts of polyurethane acrylate (PUA), 20 parts of β-hydroxyethyl methacrylate, and 5 parts of the anti-settling reinforcing agent obtained in step 1, and put them into a planetary ball mill for preliminary mixing for 2 hours to obtain a premixed liquid.

[0022] Final slurry preparation: Add 3 parts of KH550 silane coupling agent, 2 parts of phenyl (2,4,6-trimethylbenzoyl) phosphorus dioxide (photoinitiator 819), and 1.5 parts of multi-walled carbon nanotubes (toughened nanophase) pretreated with KH570 silane coupling agent to the above premixed liquid, continue ball milling for 12 hours, and pass through a 200-mesh sieve to obtain the slurry.

[0023] Example 2 Preparation of anti-settling reinforcing agent: Weigh 14g of perfluoropolyether and 3g of nano-zeolite with a particle size of 0.4μm, and stir at 100℃ for 2 hours. Add 5g of mixed powder consisting of 1.25g of polytetrafluoroethylene with a particle size of 3μm and 3.75g of polytetrafluoroethylene with a particle size of 0.4μm, heat to 200℃ and continue stirring and mixing for 2 hours. After cooling, the anti-settling reinforcing agent is obtained.

[0024] High-entropy ceramic powder pretreatment: Weigh 100g each of ZrO2, HfO2, Nb2O5, and MoO3 powders (D50=0.5μm) in equimolar ratio, place them in a planetary ball mill and dry mix for 4 hours to obtain high-entropy ceramic powder.

[0025] Slurry compounding: Take 60 parts of the mixed powder from step 2, 20 parts of epoxy acrylate (EA), 20 parts of 1,6-hexanediol diacrylate (HDDA), and 5 parts of the anti-settling reinforcing agent obtained in step 1, and put them into a planetary ball mill for preliminary mixing for 2 hours to obtain a premixed liquid.

[0026] Final slurry preparation: Add 3 parts of KH570 silane coupling agent, 2 parts of phenyl (2,4,6-trimethylbenzoyl) phosphorus dioxide (photoinitiator 819), and 1.0 part of graphene oxide nanosheets (toughened nanophase) pretreated with KH550 silane coupling agent to the above premixed liquid, continue ball milling for 12 hours, and pass through a 200-mesh sieve to obtain the slurry.

[0027] Example 3 Preparation of anti-settling enhancer: Same as in Example 1.

[0028] Pretreatment of high-entropy ceramic powder: Same as in Example 1.

[0029] Slurry compounding: Take 60 parts of the mixed powder from step 2, 15 parts of polyurethane acrylate (PUA), 25 parts of the mixed reactive diluent compounded by 1,6-hexanediol diacrylate (HDDA) and hydroxyethyl acrylate (HEA) in a mass ratio of 1:1, and 5 parts of the anti-settling reinforcing agent obtained in step 1, and put them into a planetary ball mill for preliminary mixing for 2 hours to obtain a premixed liquid.

[0030] Final slurry preparation: Add 3 parts of KH550 silane coupling agent, 2 parts of photoinitiator 819, and a mixed toughening-enhancing nanophase (totaling 1.5 parts) consisting of 1.0 part of KH570 pretreated multi-walled carbon nanotubes and 0.5 parts of KH560 pretreated zirconia nanowires to the above premixed liquid, continue ball milling for 12 hours, and pass through a 200-mesh sieve to obtain the slurry.

[0031] Comparative Example 1 Pretreatment of high-entropy ceramic powder: Same as in Example 1.

[0032] Slurry compounding: Take 60 parts of the mixed powder from step 1, 20 parts of polyurethane acrylate (PUA), and 20 parts of β-hydroxyethyl methacrylate, and mix them in a planetary ball mill for 2 hours to obtain a premixed liquid. (Note: No anti-settling reinforcing agent is prepared or added in this comparative example.) Final slurry preparation: Add 3 parts of KH550 silane coupling agent, 2 parts of photoinitiator 819, and 1.5 parts of multi-walled carbon nanotubes pretreated with KH570 to the above premixed liquid, continue ball milling for 12 hours, and pass through a 200-mesh sieve to obtain the slurry.

[0033] Comparative Example 2 Preparation of anti-settling enhancer: Same as in Example 1.

[0034] Pretreatment of high-entropy ceramic powder: Same as in Example 1.

[0035] Slurry compounding: Take 60 parts of the mixed powder from step 2, 20 parts of polyurethane acrylate (PUA), 20 parts of β-hydroxyethyl methacrylate, and 5 parts of the anti-settling reinforcing agent obtained in step 1, and put them into a planetary ball mill for preliminary mixing for 2 hours to obtain a premixed liquid.

[0036] Final slurry preparation: Add 3 parts KH550 silane coupling agent and 2 parts photoinitiator 819 to the above premixed liquid, continue ball milling for 12 hours, and pass through a 200-mesh sieve to obtain the slurry. (Note: This comparative example does not add toughening-enhancing nanophase.) Comparative Example 3 Preparation of anti-settling enhancer: Same as in Example 1.

[0037] Slurry compounding: Take 60 parts of single-component alumina (Al2O3) powder (D50=0.5μm), 20 parts of polyurethane acrylate (PUA), 20 parts of β-hydroxyethyl methacrylate, and 5 parts of the anti-settling reinforcing agent obtained in step 1, and place them in a planetary ball mill for preliminary mixing for 2 hours to obtain a premixed liquid. (Note: This comparative example uses conventional alumina powder instead of high-entropy ceramic powder.) Final slurry preparation: Add 3 parts of KH550 silane coupling agent, 2 parts of photoinitiator 819, and 1.5 parts of multi-walled carbon nanotubes pretreated with KH570 to the above premixed liquid, continue ball milling for 12 hours, and pass through a 200-mesh sieve to obtain the slurry.

[0038] Performance Testing and Result Analysis The slurries obtained from the above examples and comparative examples were subjected to performance tests. The ceramic bodies after photocuring, degreasing, and sintering (sintering conditions: 1600℃, argon protection, and holding for 2 hours) were subjected to mechanical property tests. The results are shown in Table 1.

[0039] Table 1 Comparison of properties of slurry and sintered body

[0040] Results analysis: As can be seen from Examples 1-3, the slurry prepared by this invention has a moderate viscosity (2.35-2.50 Pa·s), excellent storage stability (no sedimentation or slight suspension after 30 days of standing, easy to stir), and the resulting ceramic body after sintering has high density (>97.5%) and significantly improved fracture toughness (both above 8.7 MPa·m). 1 / 2 This fully demonstrates the universal effectiveness and superiority of the technical solution of the present invention.

[0041] Comparative Example 1 shows that, without the key anti-settling reinforcing agent of this invention, the slurry has a low initial viscosity but extremely poor stability. After standing, it severely clumps and cannot be used for subsequent printing and sintering processes, proving that the anti-settling reinforcing agent is indispensable for maintaining the stability of high-entropy ceramic slurry.

[0042] Comparative Example 2 shows that even with a high-entropy ceramic system and an anti-settling reinforcing agent, the fracture toughness of the sintered body (5.5 MPa·m) is significantly reduced without the presence of a toughening-enhancing nanophase. 1 / 2 The toughness is comparable to that of ordinary ceramics, and far lower than that of the embodiments of the present invention, which proves that the toughness-enhancing nanophase is the key to achieving high toughness.

[0043] Comparative Example 3 shows that even with the addition of anti-settling reinforcing agents and carbon nanotubes to conventional alumina ceramics, the toughness improvement effect (KIC=6.8) is significantly lower than that of the high-entropy ceramic system of the present invention (9.2 in Example 1). This strongly demonstrates that there is a synergistic toughening effect between high-entropy ceramics and toughness-enhancing nanophases, rather than a simple summation.

[0044] In summary, this invention has successfully prepared a photocurable ceramic slurry with excellent printing performance, storage stability, and ultra-high toughness by organically combining "anti-settling enhancer", "high-entropy ceramic powder" and "toughness-enhancing nanophase". The technical effect is significant and the innovation is outstanding.

[0045] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a high-toughness, high-entropy ceramic photocurable slurry, characterized in that, Includes the following steps: The perfluoropolyether and nano-zeolite powder were stirred and mixed at 90-110℃ to obtain the first mixture; Polytetrafluoroethylene powder was added to the first mixture, and the mixture was stirred and mixed at 200-220°C. After cooling, an anti-settling reinforcing agent was obtained. At least four types of metal oxide ceramic powders are mixed to form high-entropy ceramic powder; The anti-settling enhancer and high-entropy ceramic powder are simultaneously added to a prepolymer and an active diluent and ball-milled to obtain a premixed liquid. A surface modifier, a photoinitiator, and a toughening-enhancing nanophase are added to the premixed liquid, and the mixture is ball-milled to obtain the high-toughness, high-entropy ceramic photocurable slurry.

2. The method for preparing a high-toughness, high-entropy ceramic photocurable slurry according to claim 1, characterized in that, The mass ratio of the perfluoropolyether, nano zeolite powder, and polytetrafluoroethylene powder is 10~15:3:5; the polytetrafluoroethylene powder is composed of polytetrafluoroethylene with a particle size of 1-3μm and polytetrafluoroethylene with a particle size of 0.1-0.5μm in a mass ratio of 1:

3.

3. The method for preparing a high-toughness, high-entropy ceramic photocurable slurry according to claim 1, characterized in that, The toughness-enhancing nanophase is at least one of surface-modified carbon nanotubes, graphene nanosheets, or zirconium oxide nanowires, and its addition amount is 0.5%-3% of the total mass of the high-entropy ceramic powder.

4. The method for preparing a high-toughness, high-entropy ceramic photocurable slurry according to claim 1, characterized in that, The metal cations in the high-entropy ceramic powder are selected from four or five of Zr, Hf, Ti, Ta, Nb, Cr, Mo, and W, and are in equimolar or near-equimolar ratios.

5. The method for preparing a high-toughness, high-entropy ceramic photocurable slurry according to claim 1, characterized in that, The components, by mass fraction, are as follows: 50-70 parts high-entropy ceramic powder, 10-30 parts prepolymer, 10-30 parts reactive diluent, 3-7 parts anti-settling reinforcing agent, 2-6 parts surface modifier, 1-4 parts photoinitiator, and 0.5-3 parts toughening-enhancing nanophase.

6. The method for preparing a high-toughness, high-entropy ceramic photocurable slurry according to claim 1, characterized in that, The prepolymer is either polyurethane acrylate or epoxy acrylate.

7. The method for preparing a high-toughness, high-entropy ceramic photocurable slurry according to claim 1, characterized in that, The reactive diluent is either β-hydroxyethyl methacrylate or 1,6-hexanediol diacrylate.

8. A high-toughness, high-entropy ceramic photocurable slurry prepared by the preparation method according to any one of claims 1 to 5.

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