Titanium alloy artificial joint with high-toughness and ultra-wear-resistant ceramic coating and its preparation method

Abstract

This invention relates to a titanium alloy artificial joint with a high-toughness, ultra-wear-resistant ceramic coating and its preparation method. The titanium alloy artificial joint includes a titanium alloy artificial joint substrate fabricated by 3D printing. The joint surface of the titanium alloy artificial joint substrate is coated with an alumina-based ceramic coating. The alumina-based ceramic coating is obtained by plasma spraying of a mixed powder of alumina, zirconium oxide, and rare earth oxides, and then polished to a surface roughness Ra of no more than 0.05 μm. The bone-bonding surface of the titanium alloy artificial joint is formed into a porous structure layer by 3D printing. Compared with the prior art, the titanium alloy artificial joint of this invention has excellent wear resistance and toughness, and can be personalized based on precise imaging data of the patient's bones.

Description

Technical Field

[0001] This invention belongs to the field of artificial joint technology, and in particular relates to a titanium alloy artificial joint with a high-toughness and ultra-wear-resistant ceramic coating and its preparation method. Background Technology

[0002] Currently, the main material for artificial joints is cobalt-chromium-molybdenum alloy (CoCrMo). However, the problems associated with CoCrMo alloy artificial joints cannot be ignored. For example, the elastic modulus of human bone is much lower than that of CoCrMo alloy, which may lead to a "stress shielding" effect. Metal ions such as cobalt (Co), chromium (Cr), and nickel (Ni) in CoCrMo alloy are prone to leaching, which may trigger allergic reactions after implantation. CoCrMo alloy also causes relatively high wear on polyethylene materials, and long-term use can easily lead to wear debris, causing osteolysis and prosthesis loosening, resulting in a high revision rate of artificial joint prostheses. The pressure fit tolerance range of existing artificial joints is wide, which requires doctors to have extremely high surgical skills.

[0003] To address these issues, commonly used products on the market include Cyrontec's ceramic artificial joints (Biolox ceramics). While these products exhibit excellent biocompatibility, they are prone to breakage during clinical applications, especially in high-load areas, accompanied by abnormal noises during joint movement, causing discomfort to patients. Furthermore, their size and shape design are limited, failing to adapt to all anatomical structures. Zimmer Biomet has prepared a TiNbN coating on the articular surface of artificial joints using physical vapor deposition (PVD). This coating possesses high hardness, effectively resisting wear, but has low toughness, making it prone to microcracks. Additionally, the reduced surface roughness after coating treatment may weaken the lubrication effect of the articular surface. Smith & Nephew has formed a ceramic oxide coating—Oxinium Black Crystal Coating—on the articular surface of artificial joints through heat treatment. However, this coating exposes the substrate after scratches, revealing that the substrate is not very wear-resistant, leading to accelerated wear and premature failure.

[0004] Table 1 summarizes the performance indicators of artificial articular surface products currently on the market.

[0005] Table 1. Articular surface products currently on the market. CN118531335A discloses a porous coating for bio-type knee joints, its preparation, and application. It employs plasma spraying technology, using metal powders of different particle sizes to spray a titanium alloy substrate. By controlling parameters such as spraying distance, gas flow rate, and arc current, a porous coating with high porosity and high roughness is formed, ensuring that the powder is deposited in a semi-molten state to improve porosity and pore intercept. However, while this artificial joint product can increase the contact area and bonding strength with bone tissue, it still cannot solve the problems of poor long-term wear resistance and toughness inherent in artificial joints, nor can it achieve personalized fit for patients.

[0006] Therefore, none of the existing artificial joint products can simultaneously achieve long-term wear resistance, toughness, and personalized fit. There is an urgent need to develop a new type of artificial joint product for orthopedic applications. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of existing technologies that cannot simultaneously achieve long-term wear resistance, toughness, and personalized adaptability, and to provide a titanium alloy artificial joint with a high-toughness and ultra-wear-resistant ceramic coating and its preparation method.

[0008] The objective of this invention can be achieved through the following technical solutions: The present invention first provides a titanium alloy artificial joint with a high-toughness and ultra-wear-resistant ceramic coating, wherein the titanium alloy artificial joint includes a titanium alloy artificial joint substrate fabricated by 3D printing; The joint surface of the titanium alloy artificial joint substrate is coated with an alumina-based ceramic coating with a thickness of 100-250 μm; the alumina-based ceramic coating is obtained by plasma spraying of a mixed ceramic powder of alumina, zirconium oxide and rare earth oxides, and polished to a surface roughness Ra of no more than 0.05 μm. The titanium alloy artificial joint matrix has a porous structure layer formed at the bone-bonding surface by 3D printing.

[0009] Furthermore, in the alumina-based ceramic coating, the mass ratio of alumina, zirconium oxide and rare earth oxide is (75-85): (10-20): (5-10), preferably 80: 15: 5.

[0010] Furthermore, the rare earth oxide is any one or more of yttrium oxide, lanthanum oxide, and cerium oxide.

[0011] Furthermore, the particle size distribution of the mixed ceramic powder ranges from 20 to 100 μm.

[0012] Furthermore, the porous structure layer is any one or more of the following: circular, rhomboid, and gyroid.

[0013] Furthermore, the porosity of the porous structure layer is 50%-80%, the pore intercept is 200-800 μm, and the beam diameter is 200-500 μm.

[0014] Furthermore, the thickness of the porous structure layer is 500-1000 μm.

[0015] Furthermore, the surface roughness Ra of the porous structure layer is 80-150 μm.

[0016] Furthermore, the titanium alloy is specifically Ti6Al4V.

[0017] Furthermore, the titanium alloy artificial joint matrix is ​​any one of the following: knee joint, hip joint, shoulder joint, elbow joint, and ankle joint.

[0018] This invention also provides a method for preparing a titanium alloy artificial joint with a high-toughness, ultra-wear-resistant ceramic coating, comprising the following steps: S1: Acquire medical images of the target joint and reconstruct a three-dimensional joint model; S2: Based on the joint model obtained in S1, design the 3D porous structure layer of the artificial joint matrix and the bone interface to obtain a digital prosthesis model. S3: 3D printing is performed on the digital prosthesis model obtained in S2 to obtain a titanium alloy artificial joint; S4: Sandblast the joint surface of the titanium alloy artificial joint obtained in S3; S5: Plasma spraying is performed on the joint surface after sandblasting in S4 to obtain an alumina-based ceramic coating on the joint surface. S6: The titanium alloy artificial joint obtained in S5 is subjected to drag polishing to finally obtain a titanium alloy artificial joint with a high-toughness and ultra-wear-resistant ceramic coating.

[0019] Furthermore, in step S1, the medical images include CT images, and the slice thickness of the CT scan is required to be no more than 1 mm.

[0020] Furthermore, in step S1, the three-dimensional reconstructed joint model uses either Mimics or 3D Slicer software.

[0021] Furthermore, in step S2, the design of the artificial joint matrix uses either Geomagic Freeform or Siemens NX software.

[0022] Furthermore, in step S2, the porous structure layer is designed using Ntopology software.

[0023] Further, in step S3, the specific steps of the 3D printing are as follows: in a vacuum environment, medical-grade titanium alloy powder is filled into the powder hopper under the protection of an inert gas; based on the digital prosthetic model in S2, the substrate is printed layer by layer until completion using electron beam selective melting technology.

[0024] Furthermore, the parameters of the electron beam selective melting technology are as follows: electron beam power of 100-400 W, scanning speed of 500-2000 mm / s, scanning spacing of 0.05-0.2 mm, layer thickness of 20-60 μm, and substrate preheating temperature of 200-400 ℃.

[0025] Furthermore, in step S4, the abrasive used for sandblasting is alumina abrasive.

[0026] Furthermore, the particle size of the sand is 250-400 μm.

[0027] Furthermore, in step S4, the sandblasting pressure is 3-5 bar.

[0028] Furthermore, in step S4, the distance of the sandblasting is 10-20 cm.

[0029] Furthermore, in step S4, the roughness Ra of the joint surface after sandblasting is 3-8 μm.

[0030] Furthermore, in step S5, the voltage for plasma spraying is 20-60 V.

[0031] Furthermore, in step S5, the plasma spray gun power for plasma spraying is 15-40 kW.

[0032] Furthermore, in step S5, the argon flow rate for plasma spraying is 15-40 sccm.

[0033] Furthermore, in step S5, the powder feeding rate for plasma spraying is 5-25 g / min.

[0034] Furthermore, in step S5, the plasma spraying distance is 150-300 mm.

[0035] Furthermore, in step S6, the drag-and-drop polishing specifically includes rough polishing and fine polishing.

[0036] Furthermore, the workpiece rotation speed for coarse polishing is 150-250 rpm, the time is 8-12 min, and the medium is spherical ceramic particles with a particle size of 2-6 mm.

[0037] Furthermore, the workpiece is polished at a rotation speed of 20-80 rpm for 35-45 min, and the medium is spherical plastic particles with a particle size of 2-6 mm.

[0038] The titanium alloy artificial joint of this invention is not achieved through the improvement of a single technology or a simple combination of commonly used technologies. Instead, it achieves a balance of wear resistance, toughness, and biocompatibility through the synergistic optimization and creative combination of multiple dimensions, including material composition, structural design, and manufacturing process. Specifically, the core factors and improvement strategies of this invention are as follows: (1) Design and manufacturing of titanium alloy artificial joint matrix Excessively high alloy matrix modulus can lead to a "stress shielding" effect, causing surrounding bone resorption and prosthesis loosening. Furthermore, a smooth metal surface cannot form biological fixation with the bone, affecting osseointegration. Therefore, this invention uses 3D printing of titanium alloy joints based on patient CT data to perfectly match the anatomical structure, reducing abnormal wear caused by shape mismatch. In the bone-bonding interface region of the titanium alloy joint matrix, a precisely controllable porous structure is directly constructed using 3D printing, greatly promoting bone cell ingrowth, achieving biological fixation, preventing prosthesis loosening, and providing a foundation for long-term, stable function of the joint surface.

[0039] (2) Coating material composition and microstructure Traditional pure alumina ceramics are hard but brittle, while pure zirconia is tough but has slightly poor wear resistance and is prone to aging. Simply mixing the two cannot maximize the advantages of both simultaneously. Furthermore, the toughening effect of zirconia depends on its metastable tetragonal phase, and ensuring its stable existence in the coating is crucial.

[0040] This invention innovatively employs an "alumina-based" composite system, specifically using alumina as the main component to ensure the coating's ultra-high hardness and wear resistance. Zirconia is introduced, utilizing its phase transformation toughening effect. During crack propagation, a martensitic phase transformation occurs, absorbing energy and significantly improving the coating's toughness, overcoming the inherent weakness of brittle ceramic coatings. Rare earth oxides are added as stabilizers, effectively stabilizing the metastable tetragonal phase of zirconia, ensuring that the phase transformation toughening mechanism is triggered when needed, rather than failing during the preparation process. The rational ratio of these three components is a crucial factor in achieving both "high toughness" and "ultra-wear resistance."

[0041] (3) Coating preparation and post-treatment process This invention employs plasma spraying technology, which can instantly melt high-melting-point ceramic mixed powders to form a dense coating that achieves a strong mechanical bond with the titanium alloy substrate. Secondly, by precisely controlling the plasma spraying parameters, this invention achieves a wear-resistant coating of suitable thickness. This avoids the situation where an excessively thin coating easily scratches and exposes the substrate, while also reducing the risk of cracking and peeling due to excessively thick coatings caused by high internal stress. Furthermore, since excessively rough surfaces generate abrasive wear, accelerating the wear of abrasive components such as polyethylene liners, this invention also employs a drag-and-drop polishing process to polish the sprayed coating to a mirror-like finish, significantly reducing the coefficient of friction.

[0042] In summary, this invention enables the simultaneous realization of two distinctly different functional surfaces on the same joint substrate using 3D printing technology. Specifically, the joint surface of the titanium alloy substrate, through plasma spraying and drag-and-drop polishing, achieves a highly tough, ultra-wear-resistant, and smooth surface; while the bone-bonding surface of the titanium alloy substrate can be directly fabricated using 3D printing to create a porous structural layer, resulting in a biocompatible surface conducive to bone ingrowth. The resulting titanium alloy artificial joint not only effectively addresses the clinical pain points of traditional joint prostheses, such as osteolysis caused by wear debris, prosthesis loosening, and the resulting high revision rate, but also overcomes the limitations of existing products in personalized fit.

[0043] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention innovatively combines the unique advantages of titanium alloy additive manufacturing and successfully develops a high-toughness, ultra-wear-resistant ceramic-coated titanium alloy artificial joint for orthopedic applications. It can effectively solve the clinical pain points of bone resorption caused by wear debris, loosening of the prosthesis and high revision rate caused by the long-term use of traditional joint prostheses, and overcome the limitations of existing products in terms of personalized adaptation and long-term wear resistance.

[0044] (2) This invention benefits from 3D printing technology and uses high-performance titanium alloy as the main material of the joint. It not only has excellent biocompatibility and high strength, but its elastic modulus is also closer to that of human bones, which can effectively reduce the "stress shielding" effect. In addition, the combination of titanium alloy and wear-resistant coating used in this invention can significantly reduce long-term wear.

[0045] (3) The present invention uses 3D printing technology to realize the personalized customization of instruments. It can be manufactured according to the precise image data of the patient's bones, which significantly improves the surgical precision and long-term stability. It can also design and print a porous structure layer in one step at the same time to precisely control the pore structure inside the artificial joint bone interface, creating ideal conditions for bone cell ingrowth and biological fixation.

[0046] (4) The present invention significantly improves the wear resistance of titanium alloy by plasma spraying an alumina-based ceramic coating on the surface of 3D printed titanium alloy, and endows the joint surface of titanium alloy with excellent wear resistance and toughness.

[0047] (5) The price of the titanium alloy used in this invention is much lower than that of the cobalt-chromium-molybdenum alloy currently used in artificial joints; and the atmospheric plasma spraying process used in this invention is a relatively mature technology that can produce coatings in large quantities. Compared with heat treatment and physical vapor deposition technology, the cost can be reduced by one-third. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the structure of the titanium alloy artificial joint of the present invention.

[0049] Figure 2 This is a physical image of the titanium alloy artificial joint of the present invention.

[0050] Figure 3 The images shown are SEM images of the alumina-based ceramic coating on the articulated surface before and after polishing in Example 1 of this invention.

[0051] Figure 4 The results show the hardness test results of the titanium alloy artificial joint of this invention.

[0052] Figure 5 The results of the wear test on the titanium alloy artificial joint of the present invention are shown. Detailed Implementation

[0053] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0054] Unless otherwise specified, the reagents, methods, instruments, and equipment used in this invention are conventional in the art. Unless otherwise specified, the reagents and materials used in the following examples are all commercially available.

[0055] The first aspect of this invention provides a titanium alloy artificial joint with a high-toughness, ultra-wear-resistant ceramic coating. For example... Figure 1 As shown, the titanium alloy artificial joint includes a titanium alloy artificial joint substrate fabricated by 3D printing; the joint surface of the titanium alloy artificial joint substrate is coated with an alumina-based ceramic coating with a thickness of 100-250 μm; the alumina-based ceramic coating is obtained by plasma spraying of a mixed ceramic powder of alumina, zirconium oxide and rare earth oxides, and polished to a surface roughness Ra of no more than 0.05 μm; the titanium alloy artificial joint substrate has a porous structure layer formed at the bone-bonding surface by 3D printing.

[0056] In some specific embodiments, the mass ratio of alumina, zirconium oxide and rare earth oxide in the alumina-based ceramic coating is (75-85): (10-20): (5-10).

[0057] In some more specific embodiments, the mass ratios of the alumina, zirconium oxide, and rare earth oxides in the mixed ceramic powder are 80 wt%, 15 wt%, and 5 wt%, respectively.

[0058] In some specific embodiments, the rare earth oxide is any one or more of yttrium oxide, lanthanum oxide, and cerium oxide, preferably yttrium oxide.

[0059] In some specific embodiments, the mixed ceramic powder is specifically an agglomerated sintered spherical powder with a particle size distribution range of 15-45 μm.

[0060] The alumina-based ceramic coating of this invention exhibits excellent wear resistance, reducing the generation of wear debris and significantly lowering the probability of requiring revision surgery due to wear. Secondly, the alumina-based ceramic coating is chemically stable, does not readily release ions into the body, and is non-toxic, non-allergenic, and non-carcinogenic, possessing good biocompatibility. Furthermore, the alumina-based ceramic coating of this invention, after polishing to a surface roughness Ra of no more than 0.05 μm, makes joint movement smoother, reduces friction and frictional heat, further decreasing wear. Finally, the surface of the alumina-based ceramic coating has good hydrophilicity, allowing synovial fluid to better wet and form a liquid film, further reducing friction and wear.

[0061] In some specific embodiments, the porous structure layer is any one or more of the following: circular, rhomboid, and gyroid.

[0062] In some specific embodiments, the porosity of the porous structure layer is 50%-80%.

[0063] In some specific embodiments, the pore intercept of the porous structure layer is 200-800 μm.

[0064] In some specific embodiments, the beam diameter of the porous structure layer is 200-500 μm.

[0065] In some specific embodiments, the thickness of the porous structure layer is 500-800 μm.

[0066] In some specific embodiments, the surface roughness Ra of the porous structure layer is 80-100 μm.

[0067] This invention, by precisely adjusting the above parameters, can 3D print an implant that matches the host bone in mechanical properties and actively guides bone ingrowth and integration in biological terms. This greatly improves the long-term survival rate of artificial joints and the quality of life of patients, which is especially significant for young, highly active patients.

[0068] Furthermore, this invention utilizes 3D printing technology to directly integrate the titanium alloy artificial joint substrate and the porous structure layer into a single unit. The process is simple, and the pore structure can be prepared to meet the requirements through structural design and printing parameter adjustment. This avoids the complex process of first preparing the artificial joint substrate through casting and then applying a porous coating to the surface via plasma spraying.

[0069] In some specific embodiments, the titanium alloy is specifically Ti6Al4V. Thanks to 3D printing technology, the artificial joint is made of high-performance titanium alloy, which not only has excellent biocompatibility and high strength, but also has an elastic modulus (90-115 GPa) that is closer to that of human bone (10-25 GPa) than that of cobalt-chromium-molybdenum alloy (220-234 GPa), effectively reducing the "stress shielding" effect.

[0070] In some specific embodiments, the titanium alloy artificial joint matrix includes, but is not limited to, knee joints, hip joints, shoulder joints, elbow joints, and ankle joints.

[0071] A second aspect of this invention provides a method for preparing a titanium alloy artificial joint with a high-toughness, ultra-wear-resistant ceramic coating, specifically comprising the following steps: S1: Acquire medical images of the target joint and reconstruct a three-dimensional joint model; S2: Based on the joint model obtained in S1, design a porous structure layer for the artificial joint matrix and the bone-bonding surface to obtain a digital prosthesis model; S3: 3D printing is performed on the digital prosthesis model obtained in S2 to obtain a titanium alloy artificial joint; S4: Sandblast the joint surface of the titanium alloy artificial joint obtained in S3; S5: Plasma spraying is performed on the joint surface after sandblasting in S4 to obtain an alumina-based ceramic coating on the joint surface. S6: The titanium alloy artificial joint obtained in S5 is subjected to drag polishing to finally obtain a titanium alloy artificial joint with a high-toughness and ultra-wear-resistant ceramic coating.

[0072] In some specific implementations, in step S1, the medical image includes CT images, and the slice thickness of the CT scan is required to be no more than 1 mm.

[0073] In some more specific embodiments, step S1 includes a medical image further comprising magnetic resonance imaging (MRI).

[0074] This invention involves performing computed tomography (CT) or magnetic resonance imaging (MRI) on the patient's target joint (such as the knee or hip joint). CT scans provide a clearer view of bone structures and are therefore the preferred method. CT scan slice thickness should be ≤1 mm; the thinner the slice, the higher the accuracy of the reconstructed model.

[0075] In some specific implementations, in step S1, the 3D reconstructed joint model uses either Mimics or 3DSlicer software. Tools such as threshold segmentation and region growing are used to accurately outline the bone contour, generating a 3D model of the skeleton (typically output in STL format). In some specific implementations, in step S2, the artificial joint matrix is ​​designed using either Geomagic Freeform or Siemens NX software. The reconstructed skeletal STL model is imported into the aforementioned reverse engineering software, which automatically generates a smooth surface model (NURBS).

[0076] In terms of articular surface design, the articular surfaces of the artificial joint are designed based on the reconstructed healthy bone or contralateral bone model to meet biomechanical and kinematic requirements.

[0077] In the design of the bone-bonding surface, the contact surface between the designed artificial joint and the patient's bone (i.e., the trabecular bone or porous structure) must perfectly match the patient's own bone defect area to achieve "click-in" installation and maximize the preservation of healthy bone tissue.

[0078] This invention requires personalized design based on the patient's imaging data. Taking joints as an example, the main anatomical parameters referenced include joint force line, anatomical axis and its angle, joint line, Q angle, varus / valgus angle, flexion / extension gap, and femorotibia angle.

[0079] In some specific implementations, in step S2, the porous structure layer is designed using Ntopology software.

[0080] In designing the 3D porous structure layer, the artificial joint model was imported into Ntopology software for porous structure design. In the bone implantation area outside the articular surface, 3D porous structures (such as rhomboids, gyroids, etc.) were designed with a porosity of 50%-80%, a pore intercept greater than 200-800 μm, and a beam diameter of 200-500 μm. This facilitates osteoblast ingrowth (osseointegration) and achieves biological fixation.

[0081] In some specific implementations, the 3D printing steps in step S3 are as follows: medical-grade titanium alloy powder is filled into the powder hopper under inert gas protection; based on the digital prosthesis model in S2, the substrate is printed layer by layer using electron beam selective melting technology until completion.

[0082] Before printing, the finalized digital prosthetic model is imported into Magics software. The software then adds support structures (to prevent deformation and warping), optimizes the placement, and slices the model (decomposing the 3D model into layer-by-layer 2D data). During printing, a high-power electron beam selectively melts the metal powder in each layer based on the sliced ​​data, building up layer by layer until the entire part is complete. The printing process takes place in a sealed chamber filled with protective gas.

[0083] In some more specific embodiments, the parameters of the electron beam selective melting technology are: The electron beam power is 100-400 W, and the electron beam power will affect the depth and width of the molten pool. The scanning speed is 500-2000 mm / s, and the scanning speed and laser power together determine the energy input; The scanning interval is 0.05-0.2 mm, which is the distance between two scanning lines; The layer thickness is 20-60 μm. The thinner the layer, the better the surface quality, but the longer the printing time. Therefore, the layer thickness should be controlled within a suitable range. The scanning strategy is stripe scanning; The preheating temperature of the substrate is 200-400 °C. For titanium alloys, preheating the substrate to 200-400 °C can reduce residual stress.

[0084] In some specific embodiments, in step S4, the abrasive used for sandblasting is alumina abrasive.

[0085] In some more specific embodiments, the sand material is of specification F24.

[0086] In some more specific embodiments, the particle size of the sand is 250-400 μm.

[0087] In some specific implementations, the sandblasting pressure in step S4 is 3-5 bar.

[0088] In some specific implementations, in step S4, the sandblasting distance is 10-20 cm.

[0089] In some specific implementations, in step S4, the surface roughness Ra of the joint surface after sandblasting is 3-8 μm.

[0090] In some specific implementations, in step S5, the voltage for plasma spraying is 20-60 V.

[0091] In some specific implementations, in step S5, the plasma spray gun power of the plasma spraying is 15-40kw.

[0092] In some specific implementations, in step S5, the argon flow rate for plasma spraying is 15-40 sccm.

[0093] In some specific embodiments, in step S5, the powder feeding rate of the plasma spraying is 5-25 g / min.

[0094] In some specific embodiments, in step S5, the spraying distance of the plasma spraying is 150-300 mm.

[0095] In some specific implementations, step S6, the drag-and-drop polishing specifically includes rough polishing and fine polishing.

[0096] This invention performs high-precision mechanical polishing on the joint surfaces of titanium alloy artificial joints to achieve a mirror finish (surface roughness Ra < 0.05 μm) to reduce wear. Dragging polishing is a centrifugal finishing process. Its core principle is to fix the workpiece (or rotating arm) and then immerse it in a container filled with abrasive media and chemical additives. Polishing, deburring, chamfering, and surface finishing are achieved through the forced and controllable relative motion between the workpiece and the abrasive media. The effect of dragging polishing is determined by a combination of parameters, requiring fine-tuning based on the workpiece material, initial state, and target requirements.

[0097] In some more specific embodiments, the workpiece is coarsely polished at a rotation speed of 150-250 rpm for 8-12 minutes, and the medium is spherical ceramic particles with a particle size of 2-6 mm.

[0098] In some more specific embodiments, the workpiece is polished at a rotation speed of 20-80 rpm for 35-45 min, and the medium is spherical plastic particles with a particle size of 2-6 mm.

[0099] Ceramic media have high cutting forces and can be used for rough polishing and deburring; the media size is smaller than the final aperture or gap on the joint. Plastic media have medium cutting forces and can be used for general finishing; the media size is smaller than the final aperture or gap on the joint.

[0100] In some more specific embodiments, the rotation speeds of the tank and the workpiece are different and opposite, and the rotation speed ratio of the workpiece to the tank is preferably 2:1.

[0101] In some more specific embodiments, the workpiece is immersed in the polishing medium and is at a sufficient distance from the bottom of the medium, typically 1 / 2 to 2 / 3 of the container height, preferably 1 / 2 of the height.

[0102] In some more specific embodiments, the polishing medium occupies 60%-80% of the effective volume of the polishing tank, preferably 70%, and the number of workpieces must ensure sufficient space for the medium to flow.

[0103] Each of the above embodiments can be implemented individually, or in any combination of two or more. The following detailed description of specific examples will further illustrate these embodiments.

[0104] Example 1: This embodiment provides a titanium alloy artificial joint with a high-toughness, ultra-wear-resistant ceramic coating.

[0105] like Figure 1 As shown, taking the knee joint as an example, the titanium alloy artificial joint in this embodiment is based on a titanium alloy artificial joint substrate, with an alumina-based ceramic coating on the joint surface, and a 3D porous structure layer formed on the bone-bonding surface of the non-joint surface by 3D printing.

[0106] The specific preparation method of the titanium alloy artificial joint in this embodiment includes the following steps: S1: Data Acquisition and Processing Medical imaging scans: Computed tomography (CT) or magnetic resonance imaging (MRI) is performed on the patient's target joint (such as the knee or hip joint). CT scans provide a clearer view of bone structures and are the preferred method. CT scan slice thickness should be ≤1 mm; the thinner the slice, the higher the accuracy of the reconstructed model.

[0107] Data Export: Export DICOM (Digital Imaging and Communications in Medicine) format data from the hospital's PACS system for CT / MRI.

[0108] 3D Reconstruction: Two-dimensional DICOM sequence images are imported into Mimics, a professional medical 3D reconstruction software. Using tools such as thresholding and region growing, the outline of the skeleton is precisely delineated, generating a 3D model of the skeleton, typically output in STL format.

[0109] S2: Personalized Design and Modeling Reverse engineering: Import the reconstructed skeletal STL model into the reverse engineering software Geomagic Freeform to automatically generate a smooth surface model NURBS.

[0110] Implant design: In terms of joint surface design, the articular surfaces of the artificial joint are designed based on the reconstructed healthy bone or contralateral bone model to meet biomechanical and kinematic requirements. Taking a joint as an example, the main anatomical parameters referenced include joint force line, anatomical axis and its included angle, joint line, Q angle, varus / valgus angle, flexion-extension gap, and femorotibia angle.

[0111] In the design of the bone-bonding surface, the contact surface between the designed artificial joint and the patient's bone (i.e., the trabecular bone or porous structure) must perfectly match the patient's own bone defect area to achieve "click-in" installation and maximize the preservation of healthy bone tissue.

[0112] In terms of porous structure design, the artificial joint model was imported into Ntopology software for porous structure design. In the bone implantation area outside the articular surface, a rhomboid 3D porous structure was designed with a porosity of approximately 70%, a pore intercept of approximately 250 μm, and a beam diameter of 300 μm. This type of porous structure facilitates osteoblast ingrowth, achieving osseointegration and biological fixation.

[0113] S3: 3D Printing Artificial joints were fabricated using electron beam selective melting technology.

[0114] Model preparation and slicing: Import the finalized 3D model of the implant into Magics software, and add support structures (to prevent deformation and warping of parts), optimize the placement, and slice (decompose the 3D model into layer-by-layer 2D data).

[0115] Printing equipment preparation: Under the protection of inert gas (argon), fill the powder hopper with medical-grade Ti6Al4V metal powder.

[0116] Printing process: A high-power electron beam selectively melts the metal powder in each layer according to the slice data, building up layer by layer until the entire part is completed. The printing process takes place in a sealed chamber filled with protective gas.

[0117] The electron beam power was 200 W, the scanning speed was 1000 mm / s, the scanning spacing was 0.1 mm, the layer thickness was 40 μm, the scanning strategy was stripe scanning, and the substrate preheating temperature was 200 ℃.

[0118] Post-processing: Remove the printed artificial joint product from the substrate and remove the burrs from the product using a sandblasting process.

[0119] S4: Plasma spraying Pretreatment: The joint surface of the artificial joint is sandblasted using F24 grade alumina with a particle size of 250-400μm, a sandblasting pressure of 4 bar, and a sandblasting distance of 15 cm to improve the roughness of the joint surface.

[0120] Plasma spraying: Plasma spraying is performed on the joint surface using atmospheric plasma spraying technology. The voltage is 40V, the plasma spray gun power is 30 kW, the argon flow rate is 30 sccm, the powder feed rate is 20 g / min, and the spraying distance is 200 mm.

[0121] The mixed ceramic powder consists of alumina, zirconium oxide and yttrium oxide, with proportions of 80 wt%, 15 wt% and 5 wt%, respectively.

[0122] S5: Polishing High-precision mechanical polishing is performed on the joint surfaces to achieve the following: Figure 2 The mirror-like finish (surface roughness Ra < 0.05 μm) is achieved to reduce wear. Rough polishing is performed at 200 rpm for 10 min using spherical ceramic particles with a diameter of 2-6 mm. Fine polishing is performed at 50 rpm for 40 min using spherical plastic particles with a diameter of 2-6 mm. The workpiece and the tank rotate in opposite directions, with a workpiece-to-tank speed ratio of 2:1. The workpiece is immersed in the polishing medium until it is half the height above the bottom of the container, and the polishing medium occupies 70% of the effective volume of the polishing tank.

[0123] The plasma-sprayed wear-resistant coating in this embodiment has a roughness Ra of 8.15 μm after polishing. After precision polishing according to the present invention, the alumina-based ceramic coating surface achieves extremely high smoothness, with a roughness Ra value of only 0.016 μm, consistently below 0.02 μm, achieving an excellent mirror effect.

[0124] Furthermore, the overall thickness of the alumina-based ceramic coating in this embodiment is approximately 100-250 μm, far exceeding the typical thickness of other competing products (such as Oxinum coating with a thickness of 5 μm and PVD coating with a thickness of 3-6 μm), providing a thicker protective barrier for the implant. If the coating thickness is insufficient, after implantation, external abrasive particles such as bone fragments or medical device residues can easily scratch the coating surface, leading to exposure of the base metal. This can then trigger the release of harmful metal ions into surrounding tissues, exacerbating the wear process and potentially causing inflammation or rejection reactions, ultimately resulting in implantation failure and the risk of a second surgery.

[0125] The cross-sectional view of the 3D porous structure layer prepared in this embodiment is shown below. Figure 3 As shown, a distinct porous structure is formed within the 3D porous structure layer.

[0126] In this embodiment, the performance of the porous structure of the 3D porous structure layer was tested according to the ASTM 1854 standard, and the specific results are shown in Table 2.

[0127] Table 2 Performance test results of 3D porous structure layers Comparative Example 1: This comparative example is a titanium alloy artificial joint sample that has not been polished after being plasma-sprayed with a ceramic coating, i.e., a titanium alloy artificial joint sample that has been 3D printed and coated with a ceramic coating.

[0128] Comparative Example 2: This comparative example uses a commercially available cobalt-chromium-molybdenum alloy, obtained through a casting process.

[0129] The present invention also conducted the following performance tests on the titanium alloy artificial joints prepared in Example 1 and the comparative example: (1) Hardness test: This invention uses a Vickers hardness tester to test the Vickers hardness and Knoop microhardness of metallic materials and other inorganic coatings, according to GB / T 9790 Metallic Materials and Metals and Other Inorganic Coatings.

[0130] Depend on Figure 4 The hardness test results show that the hardness value of the alumina-based ceramic coating prepared in Example 1 is stable at around 800 HV, while the hardness value of the wear-resistant ceramic coating without plasma spraying is only around 350 HV, indicating that the wear-resistant coating of the present invention has excellent hardness.

[0131] (2) Wear test Wear tests were performed in accordance with ASTM F732-17 and were designed to evaluate the wear performance of ultra-high molecular weight polyethylene (UHMWPE) and artificial joint surfaces under simulated physiological conditions.

[0132] Depend on Figure 5 The wear test results show that, under two million cycles, the wear amount of polyethylene using the cobalt-chromium-molybdenum alloy of Comparative Example 2 is 18.21 mg. However, when the wear-resistant ceramic coating prepared in Example 1 is used, the wear amount of polyethylene is only 8.53 mg, which is only half that of the cobalt-chromium-molybdenum alloy.

[0133] In summary, this invention endows 3D-printed titanium alloy joint surfaces with excellent wear resistance and toughness through plasma spraying technology, which can solve clinical pain points such as osteolysis caused by wear debris, loosening of the prosthesis, and high revision rate caused by the long-term use of traditional joint prostheses.

[0134] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A titanium alloy artificial joint with a high-toughness, ultra-wear-resistant ceramic coating, characterized in that, The titanium alloy artificial joint includes a titanium alloy artificial joint matrix fabricated by 3D printing; The joint surface of the titanium alloy artificial joint substrate is coated with an alumina-based ceramic coating with a thickness of 100-250 μm; the alumina-based ceramic coating is obtained by plasma spraying of a mixed ceramic powder of alumina, zirconium oxide and rare earth oxides, and polished to a surface roughness Ra of no more than 0.05 μm. The titanium alloy artificial joint matrix has a porous structure layer formed at the bone-bonding surface by 3D printing.

2. The titanium alloy artificial joint with a high-toughness, ultra-wear-resistant ceramic coating according to claim 1, characterized in that, In the alumina-based ceramic coating, the mass ratio of alumina, zirconium oxide and rare earth oxide is (75-85): (10-20): (5-10); The rare earth oxide is any one or more of yttrium oxide, lanthanum oxide, and cerium oxide; The particle size distribution of the mixed ceramic powder ranges from 20 to 100 μm.

3. The titanium alloy artificial joint with a high-toughness, ultra-wear-resistant ceramic coating according to claim 1, characterized in that, The porous structure layer is any one or more of the following: circular, rhomboid, and gyroid. The porosity of the porous structure layer is 50%-80%, the pore intercept is 200-800 μm, and the beam diameter is 200-500 μm; The thickness of the porous structure layer is 500-1000 μm; The surface roughness Ra of the porous structure layer is 80-150 μm.

4. The titanium alloy artificial joint with a high-toughness, ultra-wear-resistant ceramic coating according to claim 1, characterized in that, The titanium alloy is specifically Ti6Al4V; The titanium alloy artificial joint matrix can be any one of the following: knee joint, hip joint, shoulder joint, elbow joint, or ankle joint.

5. A method for preparing a titanium alloy artificial joint with a high-toughness, ultra-wear-resistant ceramic coating as described in any one of claims 1-4, characterized in that, Includes the following steps: S1: Acquire medical images of the target joint and reconstruct a three-dimensional joint model; S2: Based on the joint model obtained in S1, design a porous structure layer for the artificial joint matrix and the bone-bonding surface to obtain a digital prosthesis model; S3: 3D printing is performed on the digital prosthesis model obtained in S2 to obtain a titanium alloy artificial joint; S4: Sandblast the joint surface of the titanium alloy artificial joint obtained in S3; S5: Plasma spraying is performed on the joint surface after sandblasting in S4 to obtain an alumina-based ceramic coating on the joint surface. S6: The titanium alloy artificial joint obtained in S5 is subjected to drag polishing to finally obtain a titanium alloy artificial joint with a high-toughness and ultra-wear-resistant ceramic coating.

6. The method for preparing a titanium alloy artificial joint with a high-toughness, ultra-wear-resistant ceramic coating according to claim 5, characterized in that, In step S1, the medical images include CT images, and the slice thickness of the CT scan is required to be no more than 1 mm; In step S1, the three-dimensional reconstructed joint model uses either Mimics or 3D Slicer software; In step S2, the design of the artificial joint matrix uses either Geomagic Freeform or Siemens NX software. In step S2, the porous structure layer is designed using Ntopology software.

7. The method for preparing a titanium alloy artificial joint with a high-toughness, ultra-wear-resistant ceramic coating according to claim 5, characterized in that, In step S3, the specific steps of 3D printing are as follows: In a vacuum environment, medical-grade titanium alloy powder is filled into the powder hopper under the protection of an inert gas; based on the digital prosthesis model in S2, it is printed layer by layer on the substrate using electron beam selective melting technology until completion; The parameters of the electron beam selective melting technology are as follows: The electron beam power is 100-400 W, the scanning speed is 500-2000 mm / s, the scanning spacing is 0.05-0.2 mm, the layer thickness is 20-60 μm, and the substrate preheating temperature is 200-400 ℃.

8. The method for preparing a titanium alloy artificial joint with a high-toughness, ultra-wear-resistant ceramic coating according to claim 5, characterized in that, In step S4, the abrasive used for sandblasting is alumina abrasive with a particle size of 250-400 μm; the sandblasting pressure is 3-5 bar, and the sandblasting distance is 10-20 cm. The surface roughness Ra of the joint surface after sandblasting is 3-8 μm.

9. The method for preparing a titanium alloy artificial joint with a high-toughness, ultra-wear-resistant ceramic coating according to claim 5, characterized in that, In step S5, the plasma spraying voltage is 20-60 V, the plasma spray gun power is 15-40 kW, the argon flow rate is 15-40 sccm, the powder feed rate is 5-25 g / min, and the spraying distance is 150-300 mm.

10. The method for preparing a titanium alloy artificial joint with a high-toughness, ultra-wear-resistant ceramic coating according to claim 5, characterized in that, In step S6, the drag-and-drop polishing specifically includes rough polishing and fine polishing; The coarse polishing process involves a workpiece rotation speed of 150-250 rpm for 8-12 minutes, using spherical ceramic particles with a diameter of 2-6 mm as the medium; the fine polishing process involves a workpiece rotation speed of 20-80 rpm for 35-45 minutes, using spherical plastic particles with a diameter of 2-6 mm as the medium.

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