Selective laser melting biological ceramic powder for dental restoration and preparation method thereof

Abstract

The invention discloses selective laser melting biological ceramic powder for dental restoration and a preparation method thereof, and belongs to the technical field of dental restoration materials. The composite ceramic material comprises the following raw materials in parts by weight: 50-100 parts of composite ceramic powder and 0.1-2 parts of an absorbent, the composite ceramic powder comprises at least two of Al2O3, ZrO2, SiO2 and TiO2; the absorbent comprises any one of TiC, SiC, ZrC, TiN and graphite; the fluidity of the selective laser melting biological ceramic powder for dental restoration is 39-40 s / 50 g. According to the invention, the SLM process adaptability of the material is obviously improved, the inherent biocompatibility, mechanical strength and stability of biological ceramics are considered, and the technical barrier that traditional biological ceramic powder is difficult to be directly used for selective laser melting is overcome; and a feasible material solution is provided for direct additive manufacturing of personalized dental prostheses with high performance and complex structures.

Description

Technical Field

[0001] This invention belongs to the field of dental restorative materials technology, specifically relating to a laser selective melting bioceramic powder for dental restoration and its preparation method. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Selective Laser Melting (SLM), a key branch of metal additive manufacturing, offers a revolutionary method for forming complex structural components through its high-energy beam-based layer-by-layer precision machining capabilities. Based on a three-dimensional digital model, this technology uses laser selective melting of pre-laid powder to achieve layer-by-layer accumulation manufacturing of solid parts, making it particularly suitable for rapid prototyping of small-batch, customized, and complex internal cavity components. In the field of dental restoration, SLM technology, with its advantages of high precision, high degree of freedom, and short delivery cycle, has become an important process direction for the fabrication of personalized restorations such as crowns, bridges, and implant frameworks. However, the forming quality and final performance of this technology largely depend on the physical and chemical properties of the selected powder material. Ideal SLM powders must meet several stringent requirements: high purity, excellent flow characteristics, near-perfect particle sphericity, and small particle size with a narrow distribution. These characteristics collectively ensure uniform powder spreading and consistent laser absorption and melting behavior, resulting in highly dense, defect-free formed parts.

[0004] Bioceramic materials are considered ideal candidates for dental restorations due to their excellent biocompatibility, stable chemical properties, good mechanical strength, and wear and corrosion resistance similar to natural teeth. However, bioceramic powders prepared by traditional methods often fail to meet the stringent requirements of the SLM (Selective Laser Melting) process in terms of morphology, particle size, and surface characteristics. Specifically, irregular particle morphology and low sphericity lead to poor powder flowability and insufficient powder uniformity; wide particle size distribution easily causes uneven melting and porosity defects; in addition, most bioceramics have low absorption rates for common laser wavelengths (such as the infrared band), resulting in low energy utilization and problems such as incomplete fusion or thermal stress concentration. These material-level limitations severely restrict the direct application of bioceramics in selective laser melting technology and hinder the further promotion of this technology in high-end personalized dental restorations.

[0005] Therefore, developing a bioceramic powder suitable for selective laser melting and forming, possessing excellent laser absorption characteristics, high sphericity, narrow particle size distribution, and good flowability, is a key prerequisite for promoting the large-scale application of this technology in high-performance dental restorations. It is also a technical bottleneck that urgently needs to be overcome in the current intersection of oral restoration materials and additive manufacturing. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a laser selective melting bioceramic powder for dental restoration and its preparation method. The laser selective melting bioceramic powder for dental restoration provided by the present invention improves its laser absorption rate and flowability while ensuring the particle size, sphericity, and mechanical properties of the bioceramic powder.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows: In a first aspect, the present invention provides a laser selective melting bioceramic powder for dental restoration, comprising the following raw materials in parts by weight: 50-100 parts by weight of composite ceramic powder and 0.1-2 parts by weight of absorbent; The composite ceramic powder includes at least two of Al2O3, ZrO2, SiO2, and TiO2; The absorbent includes any one of TiC, SiC, ZrC, TiN, and graphite; The fluidity of the laser selective melting bioceramic powder used for dental restoration is 39-40 s / 50g.

[0008] In some embodiments of the present invention, the laser selective melting bioceramic powder for dental restoration further includes 0.1-15 parts of flux.

[0009] In some embodiments of the present invention, the flux includes at least one of K2O and Na2O.

[0010] In some embodiments of the present invention, the particle size of the composite ceramic powder is 0.5-2 μm.

[0011] In some embodiments of the present invention, the particle size of the absorbent is 0.5-4 μm.

[0012] In some embodiments of the present invention, the laser selective melting bioceramic powder for dental restoration comprises the following raw materials in parts by weight: 80-100 parts by weight of composite ceramic powder, 0.1-1.5 parts by weight of absorbent, and 0.1-10 parts by weight of flux.

[0013] In some embodiments of the present invention, the laser selective melting bioceramic powder for dental restoration comprises the following raw materials in parts by weight: 80-100 parts by weight of composite ceramic powder and 0.1-1.5 parts by weight of absorbent. The composite ceramic powder is Al2O3, ZrO2 and SiO2, and the mass ratio of Al2O3, ZrO2 and SiO2 is (60-70):(10-30):(5-10); Alternatively, the composite ceramic powder is Al2O3 and SiO2, with a mass ratio of Al2O3 to SiO2 of (45-55):(45-55); Alternatively, the composite ceramic powder is Al2O3 and ZrO2, with a mass ratio of Al2O3 to ZrO2 of (45-55):(45-55).

[0014] In some embodiments of the present invention, the laser selective melting bioceramic powder for dental restoration comprises the following raw materials in parts by weight: 80-100 parts by weight of composite ceramic powder and 0.1-1.5 parts by weight of absorbent. The absorbent is TiC, SiC and graphite, and the mass ratio of TiC, SiC and graphite is (0.1-0.5):(0.1-0.5):(0.1-0.5). Alternatively, the absorbent is TiC and graphite, with a mass ratio of TiC to graphite of (0.1-0.5):(0.1-0.5); Alternatively, the absorbent is TiC and SiC, with a mass ratio of TiC to SiC of (0.1-0.5):(0.1-0.5).

[0015] A second aspect of the present invention provides a method for preparing the laser selective melting bioceramic powder for dental restorations described in the first aspect, comprising: The composite ceramic powder is added to water, then the additives are added, the mixture is stirred, defoamed, and filtered to obtain a slurry. The slurry is atomized and dried with hot air to obtain a mixture; The mixture is combined with the absorbent to obtain laser selective melting bioceramic powder for dental restoration.

[0016] In some embodiments of the present invention, the additives include at least one of dispersants and binders; The amount of dispersant added is 0.1-0.5% of the mass of the composite ceramic powder, and the amount of binder added is 0.5-2% of the mass of the composite ceramic powder.

[0017] In some embodiments of the present invention, composite ceramic powder is added to water, then additives are added, and the mixture is stirred at 1000-2000 r / min for 30-60 min, ultrasonically defoamed, and ground to control the concentration to 50-200 mPa. Adjust the pH to 8-10, filter, and obtain the slurry.

[0018] In some embodiments of the present invention, the concentration of composite ceramic powder in the slurry is 40-60 wt%.

[0019] In some embodiments of the present invention, a 200-300 mesh filter is used for filtration.

[0020] In some embodiments of the present invention, the droplet size after atomization is 10-100 μm.

[0021] In some embodiments of the present invention, the hot air drying process involves an inlet air temperature of 220-350°C, an outlet air temperature of 90-140°C, and a drying time of 5-30 seconds.

[0022] In some embodiments of the present invention, the mixture is calcined at 800-1450°C for 1-4 h before being mixed with the absorbent.

[0023] In some embodiments of the present invention, the mixture is aged for 20-30 hours before calcination.

[0024] A third aspect of the present invention provides an application of the laser selective melting bioceramic powder for dental restoration described in the first aspect in the field of dental restoration.

[0025] In some embodiments of the present invention, the application is to fabricate dental restorations using selective laser melting of bioceramic powder for dental restorations.

[0026] In some embodiments of the present invention, the restoration includes any one or more of a dental crown, a dental bridge, and a framework.

[0027] The beneficial effects of this invention are as follows: This invention provides a laser selective melting (SLM) bioceramic powder for dental restorations. By introducing a specific absorber into the composite ceramic matrix, the powder's absorption efficiency for laser energy is specifically enhanced, ensuring thorough melting and dense forming. Simultaneously, the powder flowability is optimized to an ideal range, guaranteeing uniform powder distribution and forming accuracy. This invention significantly improves the material's adaptability to SLM processes while also considering the inherent biocompatibility, mechanical strength, and stability of bioceramics. It successfully overcomes the technical barrier of directly using traditional bioceramic powders for laser selective melting, providing a feasible material solution for the direct additive manufacturing of high-performance, complex, and personalized dental restorations.

[0028] This invention also provides a method for preparing laser selective melting (SLM) bioceramic powder for dental restorations. This method combines water-based slurry preparation with atomized drying, offering a simple and environmentally friendly process. The uniform mixing and atomization steps of the slurry help control the sphericity and particle size distribution of the powder, resulting in a ceramic powder precursor with excellent flowability. Subsequent separate introduction and mixing of the absorbent effectively avoids absorbent loss and performance changes during high-temperature processing, ensuring its uniform distribution within the powder. Ultimately, this results in powders possessing both excellent laser absorption performance and the flow characteristics required for the process. This method is easily scalable and provides a reliable and efficient process route for the stable preparation of high-performance SLM bioceramic powders. Attached Figure Description

[0029] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0030] Figure 1 The following are morphological images of the powder after the absorbent is mixed in in Example 1 of the present invention: (a) is the morphological image of powder 1 after 0.5 wt% TiC powder is mixed in; (b) is the morphological image of powder 3 after 0.5 wt% SiC powder is mixed in; (c) is the morphological image of powder 4 after 0.1 wt% graphite powder is mixed in.

[0031] Figure 2 The following are powder morphology diagrams from Embodiment 1 of the present invention: (a) is powder 2; (b) is powder 5; (c) is powder 6; and (d) is powder 7.

[0032] Figure 3 The following are particle size distribution diagrams of powders after the absorbent is mixed in in Example 1 of the present invention: (a) Particle size distribution diagram of powder 1 after 0.5 wt% TiC powder is mixed in; (b) Particle size distribution diagram of powder 3 after 0.5 wt% SiC powder is mixed in; (c) Particle size distribution diagram of powder 4 after 0.1 wt% graphite powder is mixed in.

[0033] Figure 4 The following are particle size distribution diagrams of powder in Embodiment 1 of the present invention: (a) is the particle size distribution diagram of powder 2; (b) is the particle size distribution diagram of powder 5; (c) is the particle size distribution diagram of powder 6; and (d) is the particle size distribution diagram of powder 7.

[0034] Figure 5 The following are side views of the laser absorption rate after absorber doping in Example 1 of the present invention: (a) Laser absorption rate after 0.1 wt% graphite powder is mixed into powder 4; (b) Laser absorption rate after 0.5 wt% SiC powder is mixed into powder 3; (c) Laser absorption rate after 0.5 wt% TiC powder is mixed into powder 1.

[0035] Figure 6 The powder laser absorption rates in Embodiment 1 of the present invention are as follows: (a) is the laser absorption rate of powder 7; (b) is the laser absorption rate of powder 6; (c) is the laser absorption rate of powder 5; and (d) is the laser absorption rate of powder 2.

[0036] Figure 7 The microstructures of the laser-selective melting process obtained in Experimental Example 1 of this invention are shown in (a) as group 1, (b) as group 2, (c) as group 3, and (d) as group 4.

[0037] Figure 8 This is the macroscopic morphology of the laser-selective melting workpiece obtained in Experiment Example 1 of the present invention. Detailed Implementation

[0038] Given that existing bioceramic powders are not suitable for laser selective melting, this invention proposes a method for laser selective melting of bioceramic powders for dental restorations.

[0039] The first aspect of this invention provides a laser selective melting bioceramic powder for dental restoration, characterized in that it comprises the following raw materials in parts by weight: 50-100 parts by weight of composite ceramic powder and 0.1-2 parts by weight of absorbent. The composite ceramic powder includes at least two of Al2O3, ZrO2, SiO2, and TiO2; The absorbent includes any one of TiC, SiC, ZrC, TiN, and graphite; The fluidity of the laser selective melting bioceramic powder used for dental restoration is 39-40 s / 50g.

[0040] This invention provides a laser selective melting (SLM) bioceramic powder for dental restorations. By introducing a specific absorber into the composite ceramic matrix, the powder's absorption efficiency for laser energy is specifically enhanced, ensuring thorough melting and dense forming. Simultaneously, the powder flowability is optimized to an ideal range, guaranteeing uniform powder distribution and forming accuracy. This invention significantly improves the material's adaptability to SLM processes while also considering the inherent biocompatibility, mechanical strength, and stability of bioceramics. It successfully overcomes the technical barrier of directly using traditional bioceramic powders for laser selective melting, providing a feasible material solution for the direct additive manufacturing of high-performance, complex, and personalized dental restorations.

[0041] In this invention, the laser selective melting bioceramic powder for dental restoration further includes 0.1-15 parts of flux.

[0042] The flux includes at least one of K2O and Na2O.

[0043] In the extremely rapid melting and solidification process of SLM, the behavior of the ceramic melt determines the quality of the final component. K2O and Na2O, as powerful fluxing agents, can significantly reduce the viscosity, surface tension, and melting temperature of the melt, greatly improve melt flowability, and lower the process energy threshold.

[0044] The role of the flux is not isolated, but deeply coupled with the composite ceramic matrix and the absorbent. SiO2 in the formulation acts as a glass network forger, while K2O / Na2O, as a network modifier, breaks Si-O-Si bonds to form non-bridging oxygen, thus efficiently achieving the aforementioned effects of reducing viscosity and melting point. Together, these three components construct a system that can form a favorable glassy phase under rapid cooling of the SLM (Solid Melting Laminate). The flux can form a low-melting-point liquid phase around high-melting-point Al2O2, ZrO2, and other grains. Through a "liquid phase sintering" mechanism, it promotes the rearrangement, dissolution, and reprecipitation of high-melting-point solid particles in a very short time, thereby achieving high densification even under rapid cooling conditions. This avoids the problems of unmelted particles and high porosity commonly found in traditional pure oxide SLMs.

[0045] Good melt flowability ensures that absorbent particles are "carried" and uniformly dispersed in the molten pool, avoiding absorbent agglomeration or sedimentation caused by melt viscosity, and guaranteeing uniform energy absorption. Low-viscosity, high-wettability melts can better encapsulate absorbent particles, forming a good bond at the interface, reducing interfacial defects, and allowing the absorbent to more effectively play its reinforcing role rather than becoming a crack initiation point. The large temperature gradient in SLM is a major cause of ceramic cracking. The introduction of K2O / Na2O, on the one hand, reduces the processing temperature window by lowering the melting point, and on the other hand, the high-flowability melt helps to relax some thermal stress through viscous flow. Simultaneously, the appropriate amount of glassy phase formed during rapid cooling can "heal" microcracks, significantly improving the formation success rate and reliability of components, especially complex dental restorations.

[0046] In some embodiments of the present invention, the particle size of the composite ceramic powder is 0.5-2 μm.

[0047] In some embodiments of the present invention, the particle size of the absorbent is 0.5-4 μm.

[0048] By precisely controlling the particle size and matching relationship between the composite ceramic powder and the absorbent, the powder is guaranteed to have excellent flowability and uniformity of powder spreading. This ensures that the absorbent particles can be uniformly dispersed in the matrix powder, forming uniform and dense energy absorption points during laser treatment. In conjunction with the flux, it promotes the formation of a stable and appropriately fluid molten pool. Thus, the chemical synergy advantages of the material design are transformed into a highly dense, uniformly composed, and defect-free microstructure inside the formed part, ultimately achieving controllable and reliable performance.

[0049] In this invention, the laser selective melting bioceramic powder for dental restoration preferably comprises the following raw materials in parts by weight: 80-100 parts by weight of composite ceramic powder, 0.1-1.5 parts by weight of absorbent, and 0.1-10 parts by weight of flux.

[0050] In this invention, the laser selective melting bioceramic powder for dental restoration preferably comprises the following raw materials in parts by weight: 80-100 parts by weight of composite ceramic powder and 0.1-1.5 parts by weight of absorbent. The composite ceramic powder is Al2O3, ZrO2 and SiO2, and the mass ratio of Al2O3, ZrO2 and SiO2 is (60-70):(10-30):(5-10).

[0051] This design employs a zirconia-toughened alumina composite system. A high content of Al₂O₃ (the main crystalline phase) ensures the material's basic hardness, wear resistance, and chemical stability. An appropriate amount of ZrO₂ acts as a phase transformation toughening phase, undergoing a martensitic transformation under stress, absorbing energy, inhibiting crack propagation, and significantly improving fracture toughness. A small amount of SiO₂ acts as a flux and glass phase former, promoting liquid-phase sintering during the SLM process, reducing porosity, and adjusting the coefficient of thermal expansion to decrease residual stress. This design aims to achieve a balance between high strength, high toughness, and excellent reliability, making it an ideal choice for load-bearing restorations such as posterior crowns and bridges.

[0052] In this invention, the laser selective melting bioceramic powder for dental restoration preferably comprises the following raw materials in parts by weight: 80-100 parts by weight of composite ceramic powder and 0.1-1.5 parts by weight of absorbent. The composite ceramic powder is preferably Al2O3 and SiO2, with a mass ratio of Al2O3 to SiO2 of (45-55):(45-55).

[0053] This formulation constitutes a mullite precursor system. During the high-temperature process of SLM, the Al2O3 and SiO2 in this ratio can react to form a mullite phase, or form a microstructure with mullite as the main crystalline phase. Mullite possesses excellent creep resistance, a low coefficient of thermal expansion, good chemical stability, and certain translucency. This formulation aims to achieve excellent high-temperature dimensional stability, good biocompatibility, and aesthetic potential (a certain opalescent effect), making it more suitable for anterior tooth restorations where high long-term stability is required or certain aesthetic demands exist.

[0054] In this invention, the laser selective melting bioceramic powder for dental restoration preferably comprises the following raw materials in parts by weight: 80-100 parts by weight of composite ceramic powder and 0.1-1.5 parts by weight of absorbent. The composite ceramic powder is preferably Al2O3 and ZrO2, with a mass ratio of Al2O3 to ZrO2 of (45-55):(45-55).

[0055] This solution utilizes a classic zirconia-toughened alumina composite material. Al₂O₃ and ZrO₂ are combined in near-equal proportions, achieving complementary advantages and synergistic toughening between the two phases. Al₂O₃ provides a high-hardness and wear-resistant framework, while the high ZrO₂ content significantly enhances the material's fracture toughness through various mechanisms such as phase transformation toughening and microcrack toughening. This solution pursues an ultimate combination of strength and toughness, typically exhibiting the most outstanding comprehensive mechanical properties (such as flexural strength and fracture toughness). It is suitable for manufacturing complex fixed bridges with thin walls and long spans, or implant superstructures subjected to high occlusal forces—restoration structures with the most demanding mechanical performance requirements.

[0056] A second typical embodiment of the present invention provides a method for preparing the above-mentioned laser selective melting bioceramic powder for dental restoration, comprising: The composite ceramic powder is added to water, then the additives are added, the mixture is stirred, defoamed, and filtered to obtain a slurry. The slurry is atomized and dried with hot air to obtain a mixture; The mixture is combined with the absorbent to obtain laser selective melting bioceramic powder for dental restoration.

[0057] This invention employs a unique process design of "wet homogenization of the precursor + dry post-mixing of key functional phases" to ensure uniform mixing and high sphericity of multiple components while avoiding performance degradation of the key absorbent during the wet process. Specifically, the initial wet process (mixing, atomization, and drying) ensures that the components of the composite ceramic matrix and additives achieve molecular-level uniform mixing and granulation at the submicron scale, thus laying the foundation for the high sphericity and excellent flowability of the final powder. The subsequent dry mixing of the absorbent precisely and controllably introduces these water- or high-temperature-sensitive functional phases, maximizing their high laser absorption rate, chemical stability, and enhancing effect, ultimately yielding a high-performance SLM-specific ceramic powder with highly uniform composition, regular morphology, and intact absorbent activity.

[0058] In this invention, the purity of the composite ceramic powder must be strictly controlled, with a purity of ≥99.9%, and the content of impurity elements (such as Fe) must be strictly controlled to avoid affecting the performance of laser selective melting bioceramic powder for dental restoration.

[0059] In this invention, the additives include at least one of dispersants and binders; The amount of dispersant added is 0.1-0.5% of the mass of the composite ceramic powder, and the amount of binder added is 0.5-2% of the mass of the composite ceramic powder.

[0060] The dispersant includes, but is not limited to, any one or more of ammonium polyacrylate and ammonium citrate, and the binder includes, but is not limited to, polyvinyl alcohol (PVA).

[0061] The additives may also include defoamers, such as silicone defoamers, to reduce the bubble content in the slurry.

[0062] In this invention, composite ceramic powder is added to water, then additives are added, and the mixture is stirred at 1000-2000 r / min for 30-60 min. The mixture is then ultrasonically defoamed, and the concentration is controlled to be 50-200 mPa by grinding. Adjust the pH to 8-10, filter, and obtain the slurry.

[0063] In this invention, flux and composite ceramic powder are added together to water, and then additives (dispersants, binders, etc.) are added.

[0064] In this invention, the concentration of composite ceramic powder in the slurry is 40-60 wt%. Excessive solid content in the slurry leads to agglomeration, while insufficient solid content results in low drying efficiency.

[0065] In this invention, after stirring, ultrasonic defoaming is performed for 10-15 minutes. If necessary, the particles are refined by ball milling (zirconia ball media) to control the slurry viscosity at 50-200 mPa. Generally, the pH is adjusted to an alkaline environment of 8-10 to enhance the stability of the slurry.

[0066] In this invention, a 200-300 mesh filter is used to remove large agglomerates and impurities.

[0067] In this invention, the atomization method includes pressure atomization (pressure 0.8-2.2 MPa) or centrifugal atomization (speed 2,000-30,000 rpm), which is suitable for high solids content slurries and produces uniform particles (20-80 μm).

[0068] In this invention, the droplet size after atomization is 10-100 μm, and the uniformity of the droplet size directly affects the particle size of the finished powder.

[0069] In this invention, during hot air drying, the inlet air temperature is 220-350℃, the outlet air temperature is 90-140℃, and the drying time is 5-30 seconds. Excessive temperature can easily lead to adhesive decomposition, while insufficient temperature will result in incomplete drying.

[0070] In hot air drying, the drying medium is clean hot air that has undergone dust removal and dehumidification treatment. During drying, the droplets come into contact with the hot airflow in a counter-current or parallel flow, achieving rapid dehydration.

[0071] In this invention, after hot air drying, a combination of a cyclone separator and a bag filter can be used to collect the mixture, with a collection efficiency of ≥99%. The dried powder needs to be graded by a vibrating screen (e.g., 60-250 mesh) to remove coarse particles and agglomerates, collecting powder with a qualified particle size (usually between 60-250 mesh). Sometimes, powder from multiple production runs is also fed into a V-type mixer and mixed for more than 1 hour to ensure batch uniformity.

[0072] In this invention, the mixture is calcined at 800-1450℃ for 1-4 hours before being mixed with the absorbent. The calcination treatment improves crystallinity and removes residual binders and moisture.

[0073] In this invention, the mixture is aged for 20-30 hours before calcination. Preferably, the mixture is stored in a sealed silo for about 24 hours to make the internal moisture distribution of the powder more uniform, the performance more stable, and to facilitate subsequent molding operations.

[0074] In this invention, a three-dimensional powder mixer is used to mechanically mix the mixture and the absorbent.

[0075] A third typical embodiment of the present invention provides an application of the above-mentioned laser selective melting bioceramic powder for dental restoration in the field of dental restoration.

[0076] In this invention, the application is to fabricate dental restorations using selective laser melting of bioceramic powder for dental restorations.

[0077] In this invention, the restoration includes, but is not limited to, any one or more of dental crowns, dental bridges, and frameworks.

[0078] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0079] The alumina, zirconium oxide, silicon oxide, titanium oxide, potassium oxide, and sodium oxide used in the following examples have a purity of ≥99.9% and an average particle size of 0.5-2 μm. The raw materials used in the examples and comparative examples are all commercially available products and can be purchased.

[0080] Example 1 A laser selective melting bioceramic powder for dental restoration is prepared by the following method: After weighing, the raw material powder was mixed in a powder mixer for 4 hours. The mixed powder was then added with appropriate amounts of deionized water, ammonium polyacrylate, and polyvinyl alcohol to obtain a slurry (60% solid content). The slurry was stirred at 1500 r / min for 30 min, followed by ultrasonic defoaming for 15 min, and then filtered through a 250-mesh screen to remove impurities. The slurry was then centrifuged at 2500 r / min, with the droplet size controlled at 10-100 μm. Hot air drying was performed with an inlet air temperature of 200℃ and an outlet air temperature of 120℃ for 20 s to achieve rapid dehydration and obtain powder. The prepared powder was then sieved through a 250-mesh screen to remove impurities, large particles, and agglomerates, resulting in a mixture.

[0081] Table 1. Composition of slurry in Example 1

[0082] 0.5 wt% TiC powder was mixed into powder 1, 0.5 wt% SiC powder was mixed into powder 3, and 0.1 wt% graphite was mixed into powder 4. All three powders were mixed uniformly by stirring in a powder mixer for 24 hours to obtain laser selective melting bioceramic powder for dental restoration. The performance of the laser selective melting bioceramic powder for dental restoration obtained in this embodiment was tested.

[0083] Flowability: Strictly follow GB / T 1482-1984. Weigh 50 g of sample, pour it into the Hall effect flowmeter funnel, open the bottom hole and start timing simultaneously, and record the time it takes for all the powder to flow out. Usually, three parallel tests are required, and the average value is taken.

[0084] Loose density: According to GB / T 1479.1-2011, using a funnel with an aperture of 2.5 mm, allow the powder to flow naturally and fill a 25 cm³ area. 3 The standard cup is leveled and then weighed for calculation.

[0085] Tap density: The powder is loaded into the measuring cylinder of the tap density meter and vibrated under specified vibration conditions until the powder volume no longer changes. Then the powder is weighed and the density is calculated.

[0086] The test results are shown in Table 2.

[0087] Table 2 Properties of the powder obtained in Example 1

[0088] Comparative Example 1 This comparative example provides a laser selective melting bioceramic powder for dental restoration. The preparation method differs from powder 1 in Example 1 in that it is centrifuged at 1500 r / min (the atomized droplet size is not in the range of 10-100 μm). During hot air drying, the inlet air temperature is 200℃, the outlet air temperature is 120℃, and the drying time is 20 s, achieving rapid dehydration to obtain the powder. The remaining steps are exactly the same as in Example 1.

[0089] Comparative Example 2 This comparative example provides a laser selective melting bioceramic powder for dental restoration. The preparation method differs from powder 1 in Example 1 in that it is centrifuged at 3500 r / min (the atomized droplet size is not within the 10-100 μm range). During hot air drying, the inlet air temperature is 200℃, the outlet air temperature is 120℃, and the drying time is 20 s, achieving rapid dehydration to obtain the powder. The remaining steps are exactly the same as in Example 1.

[0090] The flowability, loose density, and tap density of the laser selective melting bioceramic powders for dental restoration obtained in Comparative Examples 1 and 2 were tested, and the results are shown in Table 3 below.

[0091] Table 3 Properties of the powders obtained in the comparative examples

[0092] Experimental Example 1 The dental restorative laser selective melting bioceramic powder (powder 1 + 0.5 wt% TiC) obtained in Example 1 was subjected to laser selective melting. The specific steps were as follows: Preprocessing Powder preparation: Dry and degas the metal powder to avoid powder agglomeration or gas content that could lead to molding defects.

[0093] Model design and slicing: Design the 3D part model using CAD software, export it as an STL format, and then use slicing software to layer the model and set process parameters such as laser power, scanning speed, and layer thickness.

[0094] Equipment debugging: Start the SLM equipment, preheat the molding chamber to the set temperature, load the processed powder into the powder cylinder, and calibrate the laser focus and the scanning platform position.

[0095] Molding and processing Powder spreading: The powder spreading roller takes powder from the powder cylinder and spreads a layer of powder evenly on the forming platform.

[0096] Selective melting: The laser beam selectively melts the powder area of ​​the current layer according to the slice contour data, so that it melts and combines with the already formed area below.

[0097] Layer stacking: After one layer is melted, the forming platform descends by the thickness of one layer, and the powder cylinder rises by the corresponding height. The powder spreading and melting steps are repeated until the entire part is formed.

[0098] Post-processing Cooling and Removing Parts: After molding is completed, wait for the molding chamber to cool to room temperature and then remove the molded substrate containing the parts.

[0099] Powder recovery: Clean and recover unmelted powder in the molding chamber, which can be reused after sieving.

[0100] Substrate separation: Separating components from the substrate by methods such as polishing.

[0101] Six experiments were conducted using “powder 1 + 0.5 wt% TiC” from Example 1, and the three-point bending properties of the laser-selected melting parts are shown in Table 4.

[0102] Table 4. Three-point bending properties of laser-selected melted parts

[0103] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A dental restorative laser selective melting bioceramic powder, characterized in that, The laser selective melting bioceramic powder for dental restoration comprises the following raw materials by weight: 50-100 parts of a composite ceramic powder, 0.1-2 parts of an absorbent; The composite ceramic powder comprises at least two of Al2O3, ZrO2, SiO2, and TiO2; The absorbent comprises any one of TiC, SiC, ZrC, TiN, and graphite; The flowability of the laser selective melting bioceramic powder for dental restoration is 39-40 s / 50g.

2. The laser selective melting bio-ceramic powder for dental restoration according to claim 1, wherein, Further comprising 0.1-15 parts of a fluxing agent; Preferably, the fluxing agent comprises at least one of K2O and Na2O.

3. The laser engineered net shaping bio-ceramic powder for dental restoration according to claim 1, wherein, The particle size of the composite ceramic powder is 0.5-2 μm; Preferably, the particle size of the absorbent is 0.5-4 μm.

4. The laser engineered net shaping bio-ceramic powder for dental restoration according to claim 2, wherein, The laser selective melting bioceramic powder for dental restoration comprises the following raw materials by weight: 80-100 parts of a composite ceramic powder, 0.1-1.5 parts of an absorbent, and 0.1-10 parts of a fluxing agent.

5. The laser engineered net shaping bio-ceramic powder for dental restoration according to claim 1, wherein, The laser selective melting bioceramic powder for dental restoration comprises the following raw materials by weight: 80-100 parts of a composite ceramic powder, 0.1-1.5 parts of an absorbent; The composite ceramic powder comprises Al2O3, ZrO2, and SiO2, and the mass ratio of Al2O3, ZrO2, and SiO2 is (60-70):(10-30):(5-10); Or, the composite ceramic powder comprises Al2O3 and SiO2, and the mass ratio of Al2O3 and SiO2 is (45-55):(45-55); Or, the composite ceramic powder comprises Al2O3 and ZrO2, and the mass ratio of Al2O3 and ZrO2 is (45-55):(45-55).

6. A method for producing a laser selective melting bioceramic powder for dental restoration according to any one of claims 1 to 5, characterized in that The method comprises: The composite ceramic powder is added into water, and then a fluxing agent is added, stirred, defoamed, and filtered to obtain a slurry; The slurry is atomized and hot-air dried to obtain a mixture; The mixture is mixed with an absorbent to obtain the laser selective melting bioceramic powder for dental restoration.

7. The production method according to claim 6, wherein The fluxing agent comprises at least one of a dispersant and a binder; Preferably, the dispersant is added in an amount of 0.1-0.5% of the mass of the composite ceramic powder, and the binder is added in an amount of 0.5-2% of the mass of the composite ceramic powder. Preferably, the composite ceramic powder is added to water, and then an auxiliary agent is added, stirred at 1000-2000 r / min for 30-60 min, defoamed by ultrasonic, and grinded to control the concentration to be 50-200 mPa s, pH is adjusted to 8-10, filtered, and a slurry is obtained; Preferably, the concentration of the composite ceramic powder in the slurry is 40-60 wt%. Preferably, a 200-300 mesh filter screen is used for filtering.

8. The production method according to claim 6, wherein The particle size of the atomized droplets is 10-100 μm; Preferably, in the hot-air drying, the inlet air temperature is 220-350℃, the outlet air temperature is 90-140℃, and the drying time is 5-30 s.

9. The production method according to claim 6, wherein The mixture is calcined at 800-1450℃ for 1-4 h, and then mixed with the absorbent. Preferably, the mixture is aged for 20-30 h before calcination.

10. Use of the laser selective melting bioceramic powder for dental restoration according to any one of claims 1-5 in the field of dental restoration. Preferably, the use is to use the laser selective melting bioceramic powder for dental restoration to make a dental restoration body. Preferably, the restoration body comprises any one or more of a crown, a bridge, and a bracket.

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