Low-Young-modulus porous titanium oxide alloy as well as preparation method and application thereof

Abstract

The invention provides a low-Young-modulus porous titanium oxide alloy and a preparation method and application thereof.The preparation method comprises the following steps that titanium powder and titanium dioxide powder are subjected to ball milling and mixing, Ti / TiO2 powder is obtained, and the mass ratio of titanium dioxide is 3-8%; the Ti / TiO2 powder and MgO particles are stirred and mixed to be uniform, the volume fraction of MgO ranges from 40% to 50%, and Ti-TiO2-MgO powder is obtained; the Ti-TiO2-MgO powder obtained through mixing is sintered, the sintering temperature ranges from 900 DEG C to 1100 DEG C, the applied pressure ranges from 20 MPa to 40 MPa, the heat preservation time ranges from 20 min to 40 min, and a Ti-O block alloy is obtained; and the sintered Ti-O block alloy is soaked in a nitric acid solution and placed in the environment of 60 DEG C to be treated. According to the technical scheme, the porous titanium oxide alloy is high in strength, low in Young modulus and high in biological activity at the same time.

Description

Technical Field

[0001] The present invention relates to the technical field of metal alloys, and in particular to a low Young's modulus porous titanium oxide alloy and a preparation method and application thereof. Background Art

[0002] Biomedical implant materials are widely used in clinical medicine, with particular demand in bone grafting. While titanium and titanium alloys (such as Ti-6Al-4V), stainless steel (316L ss), and cobalt-chromium alloys (CoCrMo) are currently the most widely used metal implant materials, they present two key challenges. First, their Young's modulus (60-120 GPa) is significantly higher than that of natural human bone (10-30 GPa), which can easily induce a "stress shielding effect" after implantation, leading to degeneration of surrounding bone tissue and poor osseointegration. Second, long-term exposure to human body fluids can release toxic metal ions, causing inflammation, allergic reactions, and even DNA damage, severely impacting implant effectiveness and patient safety.

[0003] In response to the above problems, researchers have carried out material optimization research, but there are still some problems, mainly: (1) In terms of composition control, researchers have proposed a variety of design theories for low Young's modulus titanium alloys (d-electron alloy design theory, average valence electron concentration theory, Mo equivalent empirical formula), which have significantly reduced the Young's modulus to 60GPa. They also proposed introducing porous structure design to solve the problem of Young's modulus mismatch by adjusting the morphology, size, distribution and connectivity of the implant pores. The study found that composition control has limited effect on Young's modulus. For example, b titanium alloy characterized by low Young's modulus still cannot meet the matching requirements. In comparison, porous structure design is more effective, but its disadvantage is that it will significantly weaken the material strength.

[0004] (2) The porous structure design can not only improve the stress transfer between the implant material and the bone tissue by introducing the pore adjustment modulus, but also significantly expand the surface area of the implant, avoiding premature movement and micro-movement while promoting bone regeneration and angiogenesis. Although this method is effective, it significantly weakens the material strength, and porous Ti-Zr-Nb-Ta and other high entropy alloys have the risk of cytotoxicity due to the excessive number of elements. (3) To address the bioinertness of pure titanium, mechanical, physical, or chemical methods have been used for surface modification, which has significantly improved the bioactivity of pure titanium. However, as post-processing methods, they inevitably increase the preparation time and cost, making the trade-off between bioactivity and preparation efficiency a major challenge.

[0005] Furthermore, the organic / organic salt pore-forming agents used in traditional sacrificial template technology pose toxic risks and are unsuitable for high-pressure sintering. Existing technologies demonstrate that simply optimizing composition or structural design alone is insufficient to simultaneously address modulus matching, strength retention, and biosafety. Developing new implant materials that combine low modulus, high strength, and excellent biocompatibility is a key area of research that urgently needs breakthroughs. Summary of the Invention

[0006] To address the above technical issues, the present invention discloses a low-Young's modulus porous titanium oxide alloy, its preparation method, and its application, solving the problem that pure titanium is difficult to achieve simultaneously high strength, low Young's modulus, and high bioactivity. The low Young's modulus refers to a material with a Young's modulus of no more than 30 GPa.

[0007] To this end, the technical solution adopted in the present invention is: A method for preparing a porous titanium oxide alloy with a low Young's modulus comprises the following steps: Step S1, ball-milling titanium powder and titanium dioxide powder to obtain Ti / TiO2 powder, wherein the mass proportion of titanium dioxide is 3-8%; Step S2, stirring and mixing the Ti / TiO2 powder and MgO particles, wherein the volume fraction of MgO is 40-50%, to obtain Ti-TiO2-MgO powder; the volume fraction of MgO is the volume of MgO / (the volume of Ti / TiO2 powder+the volume of MgO particles); Step S3, sintering the mixed Ti-TiO2-MgO powder at a sintering temperature of 900-1100°C, applying a pressure of 20-40 MPa, and holding time of 20-40 min to obtain a Ti-O bulk alloy; Step S4: soaking the sintered Ti-O bulk alloy in a nitric acid solution and treating it at 60° C. to remove the MgO pore-forming agent therein, thereby obtaining a porous titanium oxide alloy with a low Young's modulus.

[0008] This technical solution uses oxygen to enhance the mechanical properties of pure titanium, combines MgO as a sacrificial template, and uses SPS technology to prepare a porous structure. At the same time, in the process of removing the MgO template with nitric acid, the surface modification of the material is completed simultaneously during the preparation process, thereby giving the porous Ti-O alloy biological activity and shortening the preparation cycle.

[0009] As a further improvement of the present invention, in step S1, the ball milling speed is 200-300 rpm, and the ball milling time is 1-3 hours. Further, the ball milling speed is 250 rpm, and the ball milling time is 2 hours. Further, the ball-to-powder ratio of the ball milling is 5:1.

[0010] As a further improvement of the present invention, in the Ti / TiO2 powder, the mass proportion of titanium dioxide is 5%; As a further improvement of the present invention, in step S2, the volume fraction of the MgO particles is 40-45%. Furthermore, the volume fraction of the MgO particles is 40%. Furthermore, the MgO particles are spherical.

[0011] As a further improvement of the present invention, in step S2, the Ti / TiO2 powder and the MgO particles are mixed again by a desktop double planetary mixer.

[0012] As a further improvement of the present invention, in step S3, the sintering temperature is 1000° C., the applied pressure is 30 MPa, and the holding time is 30 min.

[0013] As a further improvement of the present invention, in step S4, the concentration of the nitric acid solution is 2-3 M, and the immersion time is 50-70 hours. Further, the concentration of the nitric acid solution is 2.5 M; further, the immersion time is 60 hours.

[0014] The present invention discloses a porous titanium oxide alloy with low Young's modulus, which is prepared by using any one of the above methods for preparing the porous titanium oxide alloy with low Young's modulus.

[0015] The present invention discloses the application of the porous titanium oxide alloy with low Young's modulus as described above, which is used as an orthopedic implant material.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The low Young's modulus porous titanium oxide alloy of the technical solution of the present invention adjusts the Young's modulus by regulating parameters such as pore size, pore distribution, and connectivity, so that it perfectly matches the Young's modulus of human bone, taking into account the characteristics of high strength, low Young's modulus, and high bioactivity. At the same time, the porous structure of the titanium alloy can also enhance the stress transfer between bone tissue and implant materials, improve biocompatibility; significantly increase the surface area of the material, help achieve early mechanical stability, and prevent early displacement and micromotion. Moreover, the preparation process is simple and the cycle is short, which provides new ideas and new methods for the development of a new generation of orthopedic implant materials that meet various clinical needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 1 and 2 are SEM images of the Ti powder, Ti / TiO2 mixed powder, and MgO particles of Example 1 of the present invention, and a particle size distribution curve of the MgO particles.

[0018] Figure 2 It is the XRD diffraction pattern of the Ti-O bulk alloy before and after the removal of the MgO pore former in the samples with different volume fractions of MgO particles added in Examples 1 to 5 of the present invention.

[0019] Figure 3 1 is an element distribution diagram of the Ti—O bulk alloy of Example 1 of the present invention obtained by EPMA-WDS analysis.

[0020] Figure 4 This is a three-dimensional reconstructed structural diagram of the porous Ti-O alloy according to Example 1 of the present invention.

[0021] Figure 5 1 and 2 show the orientation pole figures (IPF diagrams) and grain size distributions of the porous Ti-O alloy and porous pure Ti according to Example 1 of the present invention.

[0022] Figure 6 1 is the compressive stress-strain curve of the porous Ti-O alloy and porous pure Ti in Example 1 of the present invention.

[0023] Figure 7 These are the wear resistance test results of the porous Ti-O alloy and porous pure Ti according to Example 1 of the present invention.

[0024] Figure 8 These are SEM images of the porous Ti-O alloy of Example 1 of the present invention and the dense titanium oxide alloy matrix samples of Comparative Example 1 after being immersed in SBF solution for different days.

[0025] Figure 9 This is a microstructural analysis of the porous Ti-O alloy of Example 1 of the present invention and the dense titanium oxide alloy matrix samples of Comparative Example 1 after being immersed in SBF solution for 14 days.

[0026] Figure 10 3 is a comparison of SEM images of the porous pure titanium of the present invention and the porous Ti-O alloy of Example 1 under different load conditions.

[0027] Figure 11 3. It is the XPS spectra of the porous Ti-O alloy of Example 1 of the present invention and the dense sample of Comparative Example 1.

[0028] Figure 12 Schematic diagram of the mechanism of apatite formation in the porous Ti-O alloy of Example 1 of the present invention in SBF solution.

[0029] Figure 13 These are SEM images of Ti-O bulk alloys with different MgO pore former volume fractions according to Examples 1 to 5 of the present invention.

[0030] Figure 14 These are SEM images of porous Ti-O alloys after removing the pore former using different MgO pore former volume fractions in Examples 1 to 5 of the present invention.

[0031] Figure 15 1 is the compressive stress-strain curve of the porous Ti-O alloy of Examples 1 to 5 of the present invention.

[0032] Figure 16 The compressive strength and porosity of the porous Ti-O alloys of Examples 1 to 5 of the present invention are compared with the research data of the prior art on porous implant materials.

[0033] Figure 17 These are the results of comparing the compressive strength and Young's modulus of the porous Ti-O alloys of Examples 1 to 5 of the present invention with those of human bones. DETAILED DESCRIPTION

[0034] The preferred embodiments of the present invention are described in further detail below.

[0035] Example 1

[0036] The low Young's modulus porous titanium oxide alloy is prepared by the following steps: High-purity titanium powder (99.99 wt%) and titanium dioxide powder (analytical grade) were mixed in a 95:5 mass ratio and placed in a 250 mL stainless steel ball mill. The mixture was ball milled in a planetary ball mill (QM-3SP2) at 250 rpm for 2 hours, with a ball-to-powder ratio of 5:1. The mixed Ti / TiO2 powder and MgO particles were then mixed again in a tabletop dual planetary mixer for 999 minutes to ensure uniform composition. In this example, the volume fraction of MgO particles was 40 vol.% when the Ti / TiO2 powder and MgO particles were mixed.

[0037] The resulting Ti-TiO2-MgO powder was then sintered in a graphite mold using an SPS system (SPS-VI). The sintering parameters were set as follows: sintering temperature of 1000°C, applied pressure of 30 MPa, and holding time of 30 minutes. The entire heating process was monitored in real time by an infrared thermometer to obtain a Ti-O bulk alloy. To obtain a porous Ti-O alloy, the sintered Ti-O bulk alloy was immersed in a 60°C oven and treated in a 2.5 M nitric acid solution for 60 hours to remove the MgO pore-forming agent.

[0038] Comparative Example 1 Based on Example 1, the difference of this comparative example is that no pore-forming agent is added, and there is no final step of removing the MgO pore-forming agent, thereby obtaining a dense titanium oxide alloy matrix sample.

[0039] Example 2 to Example 5 Based on Example 1, the differences between Examples 2 to 5 are that the volume fractions of MgO particles are 30 vol.%, 35 vol.%, 45 vol.%, and 50 vol.%, respectively.

[0040] In Example 1, the SEM images of Ti powder, Ti / TiO2 mixed powder, and MgO particles and the particle size distribution curve of MgO particles are shown in FIG. Figure 1 As shown, Figure 1 (a) is the SEM image of Ti powder. Figure 1 (b) is the SEM image of Ti / TiO2 mixed powder. Figure 1 (c) is the SEM image of MgO particles. Figure 1 (d) is the particle size distribution curve of MgO particles. The XRD diffraction patterns of Ti-O bulk alloy before and after removing MgO pore former are shown in Figure 2. Figure 2 As shown, Figure 2 (a) is before removing the MgO pore-forming agent. Figure 2 (b) shows the case after the MgO pore former is removed. In the figure, 30 vol.% MgO added, 35 vol.% MgO added, 40 vol.% MgO added, 45 vol.% MgO added, and 50 vol.% MgO added represent examples in which the volume fraction of MgO particles added is 30 vol.%, 35 vol.%, 40 vol.%, 45 vol.%, and 50 vol.%, respectively. The element distribution of the Ti-O bulk alloy with 40 vol.% MgO pore former added in Example 1 was analyzed by EPMA-WDS. Figure 3 As shown, Figure 3 (a) in the figure is the BSE image. Figure 3 (b) in the figure is the distribution of Ti elements. Figure 3 (c) in the figure is the distribution of Mg element. Figure 3 (d) in the figure is the distribution of O elements. The three-dimensional reconstruction structure of the porous Ti-O alloy with 40 vol.% MgO pore former added is shown in the figure below. Figure 4 As shown, Figure 4 (a) is a three-dimensional reconstructed X-ray computed tomography (XCT) image. Figure 4 (b) is the orthogonal slice view of the reconstructed microstructure in the YZ, XZ and XY planes. The orientation pole figures (IPF diagrams) and grain size distributions of the porous pure Ti and the porous Ti-O alloy with 40 vol.% MgO pore former added in Example 1 are shown in Figure 2. Figure 5 As shown, Figure 5 (a) in Figure 5 (a-1) is the orientation pole figure (IPF diagram) and grain size distribution diagram of porous pure Ti. Figure 5 (b) Figure 5(b-1) is the orientation pole figure (IPF diagram) and grain size distribution diagram of Example 1. The compressive stress-strain curves of the porous Ti with 40 vol.% MgO pore-forming agent added and the porous Ti-O alloy with 40 vol.% MgO added in Example 1 are shown in FIG. Figure 6 As shown, the wear resistance test results of pure Ti and the porous Ti-O alloy of Example 1 are as follows Figure 7 As shown, Figure 7 (a) is the average friction coefficient, Figure 7 (b) is the weight loss after the test. The SEM images of the porous Ti-O alloy of Example 1 and the dense titanium oxide alloy matrix samples of Comparative Example 1 after being immersed in SBF solution for different days are shown in Figure 2. Figure 8 As shown, Figure 8 (a), (c), and (e) are SE images of the sample of Comparative Example 1 on the 3rd, 7th, and 14th days of immersion, respectively; Figure 8 (b), (d), and (f) are SEM images of the sample of Example 1 after immersion for 3 days, 7 days, and 14 days, respectively; Figure 8 (a-1), (b-1), (c-1), (d-1), (e-1), and (f-1) are Figure 8 The microstructure analysis of the porous Ti-O alloy obtained in Example 1 and the dense titanium oxide alloy matrix sample of Comparative Example 1 after immersion in SBF solution for 14 days is shown in Figure 1. Figure 9 As shown, Figure 9 (a) is the XRD diffraction pattern of the samples of Example 1 and Comparative Example 1 after being immersed in SBF solution for 14 days; Figure 9 (b) shows the surface deposition morphology and elemental composition of the porous sample in Example 1. Figure 9 (c) shows the surface deposition morphology and elemental composition corresponding to the dense sample of Comparative Example 1.

[0041] Comparison of SEM images of porous pure titanium and porous Ti-O alloy obtained in Example 1 under different load conditions Figure 10 As shown, Figure 10 (a) and Figure 10 (c) is the SEM image of porous pure titanium at loads of 150MPa and 200MPa. Figure 10 (b) and Figure 10 (d) is the SEM image of the porous Ti-O alloy of Example 1 at loads of 150 MPa and 200 MPa. The XPS spectra of the porous Ti-O alloy of Example 1 and the dense sample of Comparative Example 1 are as follows: Figure 11 As shown, Figure 11 (a) in the equation is Ti 2p, Figure 11 (b) in the figure is O 1s. The schematic diagram of the apatite formation mechanism of the sample of Example 1 in SBF solution is shown in FIG. Figure 12 As shown, Figure 12 (a) is the reaction principle diagram when porous Ti-O alloy contacts SBF solution. Figure 12 (b) is the reaction principle diagram after phosphorus-containing groups are enriched on the surface. Figure 12 (c) is the reaction principle diagram after calcium ion enrichment. Figure 12 (d) in the figure shows the reaction mechanism after the continuous deposition of calcium and phosphate ions. Initially, hydroxyl groups on the sample surface exchange with phosphorus-containing groups in the SBF solution, a process that reduces the nucleation work of apatite on the sample surface. As phosphorus-containing groups accumulate on the surface, the surface becomes negatively charged and begins to adsorb calcium ions from the SBF solution. As calcium ions accumulate, the sample surface becomes positively charged and subsequently begins to adsorb phosphate ions from the SBF solution, forming amorphous apatite. As calcium and phosphate ions continue to deposit, a highly crystalline apatite layer forms.

[0042] It can be seen that in the process of removing the MgO pore-forming agent with HNO3 solution, the surface of the material was modified simultaneously, which promoted the ion exchange on the surface of the material and the nucleation of apatite, and successfully overcame the intrinsic biological inertness problem of pure titanium.

[0043] The porous titanium oxide alloys obtained in Examples 1 to 5 were tested. The SEM images of the Ti-O bulk alloys obtained in Examples 1 to 5 are shown in FIG. Figure 13 As shown, Figure 13 (a) to (c) are examples in which the volume fraction of added MgO particles is 30 vol.%, 35 vol.%, and 40 vol.%, respectively. Figure 13 (d) in Figure 13 A partial enlarged view of the box in (c) Figure 13 (e) in the figure indicates that the volume fraction of added MgO particles is 45 vol.%. Figure 13 (f) shows that the volume fraction of added MgO particles is 50 vol.%. The SEM image of the porous Ti-O alloy after removing the pore-forming agent is shown in Figure 2. Figure 14 As shown, Figure 14 (a) to (e) are examples in which the volume fraction of added MgO particles is 30 vol.%, 35 vol.%, 40 vol.%, 45 vol.%, and 50 vol.%, respectively. Figure 14 (f) is a comparison of the porosity and density of the porous Ti-O alloys of Examples 1 to 5. The compressive stress-strain curves of the porous Ti-O alloys with different volume fractions of MgO pore formers added in Examples 1 to 5 are shown in FIG. Figure 15 The mechanical properties of porous Ti-O alloy after removing MgO pore former are shown in Table 1.

[0044] Table 1 Mechanical properties of porous Ti-O alloy after removing MgO pore former

[0045] The compressive strength and porosity of the porous Ti-O alloys of Examples 1 to 5 of the present invention are compared with the research data of the prior art on porous implant materials. Figure 16 As shown in the figure, the compressive strength and Young's modulus of the porous Ti-O alloys of Examples 1 to 5 of the present invention are compared with those of human bones. Figure 17 As shown, it can be seen that the compressive strength and Young's modulus of the porous Ti-O alloy in this embodiment are very close to those of human bones.

[0046] The above performance comparison shows that a Ti-O alloy with adjustable porous structure and controllable pore structure was successfully prepared by using spherical MgO as a pore former (SH) in combination with spark plasma sintering (SPS) technology. This porous Ti-O alloy has both high strength and excellent bioactivity.

[0047] Specifically, the Young's modulus of porous Ti-O alloys prepared with the addition of 35 vol.%, 40 vol.%, 45 vol.%, and 50 vol.% MgO was below 46 GPa. The porous Ti-O alloys prepared with the addition of 35 vol.%, 40 vol.%, and 45 vol.% MgO achieved both high strength and low Young's modulus. The porous Ti-O alloy with the addition of 40 vol.% MgO in Example 1 exhibited optimal mechanical matching, with a fracture strength of 257.8±5.2 MPa and a Young's modulus of 29.2±0.3 GPa, highly consistent with the mechanical properties of human cortical bone. X-ray computed tomography (XCT) results confirmed that its pore structure was highly interconnected, facilitating bone ingrowth, nutrient transport, and waste removal after implantation. This indicates that the significant solid solution strengthening effect of oxygen significantly enhances the yield strength of the pure titanium matrix. This strengthening effect effectively avoids structural damage caused by uneven plastic deformation under load, and increases the material's fracture strength by nearly 30% compared to porous pure titanium.

[0048] The above is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. For those skilled in the art of the present invention, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should be considered to fall within the scope of protection of the present invention.

Claims

1. A method for preparing a porous titanium oxide alloy with a low Young's modulus, characterized in that: The steps include: Step S1, ball-milling titanium powder and titanium dioxide powder to obtain Ti / TiO2 powder, wherein the mass proportion of titanium dioxide is 3-8%; Step S2, stirring and mixing the Ti / TiO2 powder and MgO particles, wherein the volume fraction of MgO is 40-50%, to obtain Ti-TiO2-MgO powder; Step S3, sintering the mixed Ti-TiO2-MgO powder at a sintering temperature of 900-1100°C, applying a pressure of 20-40 MPa, and holding time of 20-40 min to obtain a Ti-O bulk alloy; Step S4: soaking the sintered Ti-O bulk alloy in a nitric acid solution and treating it at 60° C. to remove the MgO pore-forming agent therein, thereby obtaining a porous titanium oxide alloy with a low Young's modulus.

2. The method for preparing a porous titanium oxide alloy with low Young's modulus according to claim 1, wherein: In step S1, the ball milling speed is 200-300 rpm, and the ball milling time is 1-3 hours.

3. The method for preparing a porous titanium oxide alloy with low Young's modulus according to claim 1, wherein: In Ti / TiO2 powder, titanium dioxide accounts for 5% by mass.

4. The method for preparing a porous titanium oxide alloy with low Young's modulus according to claim 1, wherein: In step S2, when mixing the Ti / TiO2 powder and the MgO particles, the volume fraction of the MgO particles is 40-45%.

5. The method for preparing a porous titanium oxide alloy with low Young's modulus according to claim 4, wherein: The volume fraction of the MgO particles is 40%, and the MgO particles are spherical.

6. The method for preparing a porous titanium oxide alloy with low Young's modulus according to claim 1, wherein: In step S3, the sintering temperature is 1000° C., the applied pressure is 30 MPa, and the holding time is 30 min.

7. The method for preparing a porous titanium oxide alloy with low Young's modulus according to claim 1, wherein: In step S4, the concentration of the nitric acid solution is 2-3 M, and the soaking time is 50-70 h.

8. A porous titanium oxide alloy with a low Young's modulus, characterized in that: The porous titanium oxide alloy with low Young's modulus is prepared by the preparation method of any one of claims 1 to 6.

9. The use of the low Young's modulus porous titanium oxide alloy according to claim 8, characterized in that: Used as orthopedic implant material.

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