A method for preparing a strontium titanate modified layer on the surface of zirconia based on the impregnation-thermal treatment method, products and applications

Abstract

This invention discloses a method for preparing a strontium titanate modified layer on the surface of zirconia based on an impregnation-heat treatment method, comprising: (1) mixing titanium sulfate, urea and water to obtain a precursor liquid A, placing zirconia ceramic in the precursor liquid A, heating to boiling and maintaining for a period of time, then removing the zirconia ceramic, and after heat treatment A, preparing a titanium dioxide film on the surface of zirconia; (2) mixing H2O2 aqueous solution, ammonia and deionized water, adding metatitanic acid and stirring to dissolve, obtaining a precursor liquid B, placing the zirconia with the titanium dioxide film in the precursor liquid B, and allowing it to stand and react for a period of time at room temperature, depositing zirconia modified with a titanium dioxide precursor layer; (3) dissolving strontium acetate, or a mixed salt composed of calcium acetate and / or magnesium acetate and strontium acetate in deionized water to obtain an impregnation treatment solution, placing the zirconia modified with the titanium dioxide precursor layer in the impregnation treatment solution, allowing it to stand and react for a period of time, and then removing it, and after heat treatment B, preparing a strontium titanate modified layer on the surface of zirconia. The strontium titanate layer prepared on the surface of zirconia ceramic in this invention is tightly attached to the zirconia substrate and has high hydrophilicity, which is conducive to the adhesion of proteins and cells in the human body. At the same time, it can release active factors such as strontium ions for a long time to promote bone formation and bone regeneration at the implantation site, ultimately enhancing the osseointegration capacity of the zirconia implant.

Description

Technical Field

[0001] This invention relates to the technical field of zirconia ceramic surface modification, and in particular to a method, product, and application for preparing a strontium titanate modified layer on the zirconia surface based on an impregnation-heat treatment method. Background Technology

[0002] Zirconia ceramics are widely used in the implant field due to their corrosion resistance, chemical stability, good biocompatibility, and superior mechanical properties. However, the bioinertness and weak osseointegration capacity of zirconia itself severely limit the clinical application and promotion of its implant products. To improve the bioactivity and osseointegration capacity of zirconia implants, sandblasting and acid etching techniques are commonly used clinically to increase the surface roughness of zirconia, increase the coupling sites between the surface and bone, and increase the number of active functional groups. However, the former easily causes microcracks on the zirconia surface, while the latter has extremely limited effect on modifying chemically inert zirconia. In addition to sandblasting and acid etching, laser treatment, ion implantation, biomimetic deposition, and biological modification techniques are also used to modify the surface of zirconia implants, but the modification effects of these techniques are limited and none of them can achieve the ideal modification effect.

[0003] Strontium plays a vital role in human bone health, responsible for improving bone strength and protecting bone health, and is an essential element for the human body. In the treatment of bone defects, strontium has a dual regulatory effect on bone regeneration and repair: it promotes osteoblast proliferation and differentiation while inhibiting osteoclast proliferation and differentiation, ultimately promoting bone formation and inhibiting bone resorption. Compared with growth factors and other factors and drugs used for bone regeneration, strontium has advantages such as low cost, low risk, and good stability. Clinically, it is often used to treat osteoporosis (strontium ranitidine) and to modify artificial bone repair materials to improve osteogenic capacity. Besides strontium, elements such as calcium, magnesium, and zinc (calcium and magnesium are both in the same group as strontium) also have the ability to promote bone formation and regeneration.

[0004] Li et al. (Magnetron sputtering of strontium nanolayer on zirconia implant to enhance osteogenesis, Materials Science & Engineering C, 2021.5.19) disclosed a method for depositing strontium nanolayers on zirconia implants using magnetron sputtering to enhance osteogenic activity. This technique employs physical deposition to deposit a strontium titanate nanolayer coating on the zirconia implant surface. However, the resulting strontium titanate nanolayer coating is as thick as 400 nm, while the Sr content in the coating is only 1.16 ± 0.18 at% ( Figure 3 Moreover, the improvement in hydrophilicity is quite limited, and its apparent contact angle is still as high as 87±9°. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention discloses a method for constructing a strontium titanate modification layer on the surface of a zirconia implant. The strontium titanate layer prepared on the zirconia ceramic surface adheres tightly to the zirconia substrate, exhibits high hydrophilicity, which is beneficial for the adhesion of proteins and cells in the human body. At the same time, it is non-toxic and non-corrosive to human cells and tissues, and can release active factors such as strontium ions over a long period of time to promote bone formation and bone regeneration at the implantation site, ultimately enhancing the osseointegration capacity of the zirconia implant. This invention provides a novel technical system for the surface modification of zirconia implants, thereby promoting the further development and in-depth application of zirconia implants.

[0006] The specific technical solution is as follows:

[0007] A method for preparing a strontium titanate modified layer on a zirconium oxide surface based on an impregnation-heat treatment method includes:

[0008] (1) Titanium sulfate, urea and water are mixed to obtain precursor liquid A. Zirconia ceramic is placed in precursor liquid A and heated to boiling state for a period of time. Then the zirconia ceramic is taken out and heat-treated A to obtain titanium dioxide film on the surface of zirconia.

[0009] (2) Mix H2O2 aqueous solution, ammonia water and deionized water, add metatitanic acid and stir to dissolve to obtain precursor liquid B. Place the zirconium oxide with titanium dioxide film prepared in precursor liquid B and let it stand at room temperature for a period of time to deposit zirconium oxide modified with titanium dioxide precursor layer.

[0010] (3) Strontium acetate, or a mixed salt of calcium acetate and / or magnesium acetate and strontium acetate, is dissolved in deionized water to obtain an impregnation solution. Zirconia modified with a titanium dioxide precursor layer is placed in the impregnation solution and allowed to stand for a period of time before being taken out. After heat treatment B, a strontium titanate modified layer is prepared on the surface of the zirconia.

[0011] This invention deposits two titanium dioxide layers on the surface of zirconia ceramic using an impregnation-heat treatment method. Different preparation processes impart different morphologies, structures, and reactivity to the two titanium dioxide layers. Furthermore, by introducing different types of salt solutions, the composition, morphology, and structure of the in-situ generated strontium titanate modified layer are controlled. Finally, a strontium titanate layer containing osteogenic elements such as calcium and magnesium, which is tightly bonded to the substrate, is prepared on the zirconia surface. Zirconia implants modified with this strontium titanate layer not only have high hydrophilicity, which is conducive to the adhesion of proteins and cells in the human body, but also release strontium ions, calcium ions, and magnesium ions at the affected site for a long period after implantation to promote the formation of new bone tissue, thus significantly improving its osseointegration capacity.

[0012] Experiments have shown that if only one layer of titanium dioxide is deposited, a strontium titanate modified layer cannot be prepared on the surface of zirconia ceramics; if the titanium source selected in step (1) is changed, such as replacing titanium sulfate with tetrabutyl titanate, a titanium dioxide layer cannot be deposited; and if the heat treatment process in step (3) is replaced with a hydrothermal method, the titanium dioxide cannot be converted into strontium titanate in situ, and the titanium dioxide layer will peel off from the zirconia surface.

[0013] In step (1):

[0014] The combination of titanium sulfate and urea ensures that the precursor fluid A is stable at room temperature. Only when it is heated will it slowly provide an alkaline atmosphere to combine with titanium ions to form a precipitate, thus stabilizing and controlling the reaction process.

[0015] Preferred:

[0016] The molar ratio of titanium sulfate to urea is 1:(1-7), more preferably 1:(3-7).

[0017] The concentration of titanium sulfate in precursor fluid A is 0.1–1.0 mol / L, more preferably 0.3–1.0 mol / L.

[0018] In step (1), heat to boiling and maintain for 5 to 40 minutes to allow titanium to precipitate.

[0019] Preferably, the heat treatment A is performed at a temperature of 800–1000°C and a holding time of 10–60 min.

[0020] Further preferably, the heat treatment A is performed at a temperature of 850–950°C.

[0021] Metatitanic acid (H2TiO3) is insoluble in deionized water, but soluble in a mixed solution of H2O2 / ammonia. In step (2), when metatitanic acid is added to precursor solution B, it will be converted into ammonium pertitanate solution and slowly degraded under static conditions at room temperature to obtain titanium dioxide precursor layer, i.e., the second titanium dioxide layer.

[0022] Preferred:

[0023] Based on the number of moles of H2O2 in the H2O2 aqueous solution, the molar ratio of H2O2 aqueous solution to metatitanic acid is (3.7~5.2):1;

[0024] Experiments have shown that if too much H2O2 is added in this step, it will inhibit the formation of the titanium dioxide precursor layer, resulting in a low formation rate of strontium titanate.

[0025] Preferred:

[0026] Based on the molar number of ammonium ions in ammonia water, the molar ratio of ammonia water to metatitanic acid is (2.0~2.4):1;

[0027] The concentration of metatitanic acid in precursor fluid B is 0.02–0.20 g / mL, more preferably 0.07–0.12 g / mL.

[0028] In step (2), the reaction is allowed to stand at room temperature for 6 to 48 hours.

[0029] In step (3), when the zirconium oxide modified with the titanium dioxide precursor layer is placed in the impregnation solution and left to stand, the acetates such as strontium acetate, calcium acetate, and magnesium acetate in the impregnation solution will be adsorbed and enter the titanium dioxide precursor layer. During the heat treatment stage, the strontium ions, calcium ions, and magnesium ions in the acetates will undergo a solid-phase reaction with the titanium dioxide at high temperature to generate strontium titanate or strontium titanate in calcium and magnesium solid solution.

[0030] Preferably, the salt concentration in the impregnation solution is 0.05–0.5 mol / L; more preferably, it is 0.15–0.2 mol / L.

[0031] In this step, when only strontium acetate is added, the salt concentration is the same as the strontium acetate concentration.

[0032] When a mixed salt consisting of calcium acetate and / or magnesium acetate and strontium acetate is added, the salt concentration is the total concentration of the mixed salt.

[0033] Experiments revealed that, in this step, the only suitable strontium, calcium, and magnesium salts are acetates. If nitrates are used instead, taking strontium nitrate as an example, the resulting strontium titanate modified layer exhibits poor morphological uniformity and numerous protrusions and sharp edges on the surface, which is detrimental to early cell adhesion.

[0034] In step (3), the reaction is allowed to stand for 6–48 hours;

[0035] Preferred:

[0036] The heat treatment B is performed at a temperature of 600–800°C, a holding time of 1–5 h, and a heating rate of 1–3°C / min. Experiments have shown that when the heating rate is too high, such as 5°C / min, the overall structure of the prepared strontium titanate modified layer is relatively loose and it is easy to detach from the zirconium oxide surface.

[0037] Further optimization involves a heat treatment temperature of 700–800℃, a holding time of 1–2 h, and a heating rate of 1.5–3.0℃ / min.

[0038] When the heating rate is less than 1.5℃ / min, the morphology of the prepared strontium titanate modified layer is not significantly different, but the required heating time is longer and the energy consumption is significantly increased.

[0039] The present invention also discloses zirconium oxide with a strontium titanate modified layer on its surface prepared according to the method.

[0040] When only strontium acetate is added in step (3), the resulting strontium titanate modified layer is a granular layer evenly distributed on the zirconium oxide surface with a thickness of about 150 nm. Due to the different heating rates during heat treatment, the sintering state will vary, and the specific morphology of the strontium titanate layer will be different under different preparation conditions. When the heating rate of heat treatment B is 1-3 °C / min, liquid phase sintering mainly occurs. The strontium titanate layer is mainly composed of a glass phase structure and nanoparticles with a particle size of 20-40 nm dispersed therein. The surface is relatively smooth, and the size and number of pores and defects are minimal. When the heating rate is greater than 3 °C / min, liquid phase sintering decreases, and the strontium titanate layer is composed of glass phase regions with a size of 150-200 nm and nanoparticles with a particle size of 40-60 nm interleaved. The overall structure is relatively loose, the density decreases, and the defects increase, making it easy to break and peel off during the implantation process and in the human body environment.

[0041] When strontium acetate and calcium acetate are added in step (3), a calcium solid solution strontium titanate modified layer is prepared. At this time, the strontium titanate modified layer is about 150 nm thick and is composed of nanoparticles of 40-60 nm. At the same time, obvious sintering necks appear between the particles, and pores are distributed in a continuous channel shape at the grain edge.

[0042] When strontium acetate and magnesium acetate are added in step (3), a magnesium solid solution strontium titanate modified layer is prepared. At this time, the thickness of the strontium titanate layer is about 150-200 nm, and the surface is composed of nanoparticles of 20-60 nm. Among them, a large number of 20-30 nm nanoparticles undergo ring agglomeration, and some 40-60 nm nanoparticles have sintering necks, but the degree of sintering is not high.

[0043] When strontium acetate, calcium acetate and magnesium acetate are added in step (3), a magnesium-calcium co-solution strontium titanate modified layer is prepared. At this time, the strontium titanate modified layer is about 250 nm thick and consists of small particles of 10-20 nm and large particles of 50-100 nm. The two types of nanoparticles agglomerate and are tightly packed. It is speculated that the uneven composition in the region caused by the solid solution of calcium and magnesium elements leads to the appearance of two types of nanoparticle aggregation states.

[0044] This invention also discloses the application of the zirconium oxide with a strontium titanate-modified surface in the field of bioimplant materials.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] This invention discloses a method for constructing a strontium titanate modified layer on the surface of a zirconia implant. A strontium titanate modified layer is successfully prepared on the zirconia surface by an impregnation-heat treatment method. By controlling the heat treatment regime and the type of salt introduced, the composition, morphology and structure of the strontium titanate layer are regulated. Finally, a strontium titanate modified layer with tight adhesion to the substrate surface and controllable morphology and composition is obtained on the zirconia surface.

[0047] This invention provides a strontium titanate-modified layer on the surface of zirconia, with a thickness of approximately 150–250 nm. Under different preparation conditions, this layer consists of nanoparticles of varying sizes and glass phase structures of different dimensions. The strontium titanate layer adheres tightly to the zirconia substrate, exhibiting no obvious defects and is not easily damaged or peeled off. It also possesses high hydrophilicity, which is beneficial for the adhesion of proteins and cells in the early stages of implantation. The strontium titanate layer (containing dissolved calcium, magnesium, and other elements) introduces osteogenic elements such as strontium, calcium, and magnesium into the surface of the zirconia implant and releases strontium into the implantation site long-term after implantation. Ions such as calcium and magnesium ions promote osteoblast proliferation and differentiation, and the formation of new bone tissue, thereby improving the osseointegration capacity and implantation success rate of zirconia implants. Strontium titanate has been applied in the field of titanium implant surface modification, and its safety and osteogenic properties have been proven. It is non-toxic and non-corrosive to the human body, has a high safety factor, and is relatively stable, not prone to decomposition and dissociation, and can be implanted for a long time in the complex human body environment with good biocompatibility. In addition, calcium and magnesium are essential elements for the human body and, like strontium, play an important role in bone formation and bone regeneration. In summary, the highly hydrophilic surface of the strontium titanate modified layer can provide a better adhesion environment for proteins and cells in the early stages of implantation. The active ions such as strontium, calcium, and magnesium ions contained in it can stimulate osteoblast proliferation and differentiation to promote new bone formation, thereby improving the osseointegration capacity of zirconia implants and enhancing their implantation therapeutic effect. This provides a new modification scheme and approach for zirconia implant surface modification. Attached Figure Description

[0048] Figure 1 The image shows a SEM image of the zirconium oxide with a titanium dioxide film prepared in step 1) of Example 1.

[0049] Figure 2 The image shows a SEM image of the zirconium oxide modified with a titanium dioxide precursor layer prepared in step 2) of Example 1.

[0050] Figure 3 The XRD pattern of the strontium titanate modified layer on the zirconium oxide surface prepared in Example 1;

[0051] Figure 4 SEM images, EDS images, and elemental relative content diagrams of the strontium titanate modified layer on the zirconium oxide surface prepared in Example 1;

[0052] Figure 5This is a visual contact angle image of the strontium titanate modified layer on the zirconium oxide surface prepared in Example 1;

[0053] Figure 6 The XRD pattern of the strontium titanate modified layer on the zirconium oxide surface prepared in Example 7;

[0054] Figure 7 SEM images, EDS images, and elemental relative content diagrams of the strontium titanate modified layer on the zirconium oxide surface prepared in Example 7;

[0055] Figure 8 This is a visual contact angle image of the strontium titanate modified layer on the zirconium oxide surface prepared in Example 7;

[0056] Figure 9 The XRD pattern of the strontium titanate modified layer on the zirconium oxide surface prepared in Example 9;

[0057] Figure 10 SEM images, EDS images, and relative elemental content diagrams of the strontium titanate modified layer on the zirconium oxide surface prepared in Example 9;

[0058] Figure 11 This is a visual contact angle image of the strontium titanate modified layer on the zirconium oxide surface prepared in Example 9;

[0059] Figure 12 The XRD pattern of the strontium titanate modified layer on the zirconium oxide surface prepared in Example 11;

[0060] Figure 13 SEM images, EDS images, and relative elemental content diagrams of the strontium titanate modified layer on the zirconium oxide surface prepared in Example 11;

[0061] Figure 14 This is a visual contact angle image of the strontium titanate modified layer on the zirconium oxide surface prepared in Example 11;

[0062] Figure 15 XRD pattern and planar SEM image of the product prepared for Comparative Example 1;

[0063] Figure 16 SEM image of the product prepared in Comparative Example 2;

[0064] Figure 17 SEM image of the product prepared in Comparative Example 3;

[0065] Figure 18 XRD pattern and SEM image of the product prepared for Comparative Example 4;

[0066] Figure 19 SEM image of the product prepared in Comparative Example 5;

[0067] Figure 20SEM image of the product prepared in Comparative Example 6. Detailed Implementation

[0068] The present invention will be described in further detail below with reference to embodiments and comparative examples, but the implementation of the present invention is not limited thereto.

[0069] Example 1

[0070] 1) Titanium sulfate and urea were dissolved in deionized water at a molar ratio of 1:3 to prepare a precursor solution A with a titanium sulfate concentration of 0.3 mol / L. Zirconia ceramic was placed in it and heated to boiling state for 15 min. Then the zirconia ceramic was taken out and kept at 900℃ for 30 min. A titanium dioxide film was successfully prepared on the surface of zirconia.

[0071] Figure 1 The image shows a SEM image of the zirconium oxide with a titanium dioxide film prepared in this step. It is observed that the titanium dioxide film is uniformly distributed and is composed of aggregated titanium dioxide nanoparticles with a particle size of 30-45 nm.

[0072] 2) Mix 30 wt% H2O2 aqueous solution and deionized water at a volume ratio of 1.5:1 to obtain 40 mL of mixed solution. Add 9 mL of concentrated ammonia (25 wt%) and stir until homogeneous. Then add 3.4 g of metatitanic acid (based on the molar ratio of H2O2 aqueous solution to metatitanic acid, the molar ratio of H2O2 aqueous solution to metatitanic acid is 3.7:1; based on the molar ratio of ammonium ions in ammonia water, the molar ratio of ammonia water to metatitanic acid is 2:1, the same below) and stir until dissolved to obtain precursor solution B with a concentration of 0.07 g / mL. Place the zirconium oxide with titanium dioxide film prepared in it and let it stand at room temperature for 12 h to deposit zirconium oxide modified with titanium dioxide precursor layer.

[0073] Figure 2 The SEM image of the zirconium oxide modified with the titanium dioxide precursor layer prepared in this step shows that the titanium dioxide precursor layer is composed of titanium dioxide particles with a particle size of less than 10 nm.

[0074] 3) Dissolve 0.92 g of strontium acetate in 30 mL of deionized water to obtain an impregnation solution with a concentration of 0.15 mol / L. Impregnate the zirconium oxide modified with the titanium dioxide precursor layer in the solution, let it stand for 24 h, and then take it out and place it in a muffle furnace. Heat it to 700 °C at a heating rate of 1.5 °C / min and hold it for 1 h for heat treatment. After heat treatment, a strontium titanate modified layer is prepared on the zirconium oxide surface.

[0075] Figure 3(a) and (b) are XRD patterns of the sample prepared in this embodiment in different diffraction angle ranges. It was observed that the main phase of the sample is zirconium oxide as the base component, and strontium titanate is also present. The main peak (110) of strontium titanate appears near 32.4°, which proves the formation of strontium titanate.

[0076] Figure 4 The cross-sectional SEM images, planar SEM images, corresponding EDS images, and elemental relative content diagrams of the sample prepared in this embodiment show that the strontium titanate modified layer of the sample is approximately 150 nm thick, and the surface morphology consists of nanoparticles with a particle size of 20–40 nm dispersed in a smooth glass phase structure. The glass phase structure contains isolated closed pores. The EDS images indicate that the sample surface contains elements such as strontium, further confirming the presence of strontium titanate. The elemental relative content diagram specifically shows that the relative strontium content in the strontium titanate modified layer of this sample is 2.49 at% (unless otherwise specified, all elemental relative contents in this invention refer to atomic content).

[0077] Figure 5 Images of the apparent contact angles of the sample prepared in this embodiment and the unmodified zirconia were observed. It was found that the apparent contact angle of the zirconia sample modified with strontium titanate (20.5°) was much smaller than that of the unmodified zirconia sample (62.3°). This indicates that the strontium titanate modification layer can significantly improve the hydrophilicity of the zirconia surface, which is conducive to the adsorption of proteins and the adhesion and proliferation of osteoblasts in the early stages of implantation.

[0078] Example 2

[0079] The preparation process is basically the same as in Example 1, except for step 2):

[0080] Replace the volume ratio of H2O2 aqueous solution to deionized water with 2:1, the volume of the mixed solution remains 40 mL, and the molar ratio of H2O2 aqueous solution to metatitanic acid is 4.4:1.

[0081] Characterized by XRD and SEM, the phase composition and morphology of the zirconium oxide modified with strontium titanate layer prepared in this example are basically the same as those in Example 1.

[0082] Example 3

[0083] The preparation process is basically the same as in Example 1, except for step 2):

[0084] When the amount of metatitanic acid added was replaced with 4.8g, the molar ratio of H2O2 aqueous solution to metatitanic acid was 5.2:1, resulting in a precursor solution with a concentration of 0.12g / mL.

[0085] Characterized by XRD and SEM, the phase composition and morphology of the zirconium oxide modified with strontium titanate layer prepared in this example are basically the same as those in Example 1.

[0086] Example 4

[0087] The preparation process is basically the same as in Example 1, except for step 3):

[0088] When the mass of strontium acetate is replaced with 1.2 g, an impregnation solution with a concentration of 0.2 mol / L is obtained.

[0089] Characterized by XRD and SEM, the phase composition and morphology of the zirconium oxide modified with strontium titanate layer prepared in this example are basically the same as those in Example 1.

[0090] Example 5

[0091] The preparation process is basically the same as in Example 1, except that the heating rate of the heat treatment is replaced with 1℃ / min in step 3).

[0092] XRD and SEM characterization showed that the phase composition and morphology of the zirconium oxide modified with a strontium titanate layer prepared in this example were basically the same as those in Example 1. However, a further decrease in the heating rate would lead to a longer heating time, unnecessary energy consumption, and an increase in production costs.

[0093] Example 6

[0094] The preparation process is basically the same as in Example 1, except that in step 3), the heating rate of the heat treatment is replaced with 3℃ / min.

[0095] Characterized by XRD and SEM, the phase composition and morphology of the zirconium oxide modified with strontium titanate layer prepared in this example are basically the same as those in Example 1.

[0096] Example 7

[0097] The preparation process is basically the same as in Example 1, except for step 3):

[0098] 0.46 g of strontium acetate and 0.36 g of calcium acetate were dissolved in 30 mL of deionized water to prepare an impregnation solution with a total salt concentration of 0.15 mol / L. The molar ratio of strontium acetate to calcium acetate was 1:1.

[0099] Figure 6(a) and (b) are XRD patterns of the sample prepared in this embodiment in different diffraction angle ranges, respectively. It was observed that the main phase of the sample is zirconium oxide as the base component, and strontium titanate is also present. The main peak of strontium titanate (110) plane appears at around 32.4°, which proves the formation of strontium titanate. At the same time, compared with the standard peak of strontium titanate in Example 1, the diffraction peak of the (110) plane has a more obvious shift towards the larger angle direction. This is because calcium ions dissolve in strontium titanate and replace strontium, causing lattice distortion. This can indirectly prove the introduction of calcium element.

[0100] Figure 7 The cross-sectional SEM images, planar SEM images, corresponding EDS images, and elemental relative content diagrams of the sample prepared in this embodiment show that the strontium titanate modified layer of the sample is approximately 150 nm thick, and its surface exhibits solid-state sintering characteristics with a particle size of 40–60 nm. Obvious sintering necks are observed between the particles, with significant neck growth. Pores are distributed in a continuous channel pattern at the grain edges. The EDS images indicate that the sample surface contains elements such as strontium and calcium, further confirming the formation of strontium titanate and the successful introduction of calcium. The elemental relative content diagram specifically shows that the relative content of strontium in the strontium titanate modified layer of this sample is 1.32%, and the relative content of calcium is 5.71%.

[0101] Figure 8 Images of the apparent contact angles of the sample prepared in this embodiment and the unmodified zirconia show that the apparent contact angle of the zirconia sample modified with the calcium solid solution strontium titanate layer (14.9°) is much smaller than that of the unmodified zirconia sample (62.3°). This indicates that the calcium solid solution strontium titanate modification layer can significantly improve the hydrophilicity of the zirconia surface, which is conducive to the adsorption of proteins and the adhesion and proliferation of osteoblasts in the early stages of implantation.

[0102] Example 8

[0103] The preparation process is basically the same as in Example 7, except for step 3):

[0104] 0.61 g of strontium acetate and 0.48 g of calcium acetate were dissolved in 30 mL of deionized water to prepare an impregnation solution with a total salt concentration of 0.2 mol / L. The molar ratio of strontium acetate to calcium acetate was 1:1.

[0105] XRD and SEM characterization showed that the phase composition and morphology of the zirconium oxide modified with strontium titanate layer prepared in this example were basically the same as those in Example 7.

[0106] Example 9

[0107] The preparation process is basically the same as in Example 1, except for step 3):

[0108] 0.46 g of strontium acetate and 0.32 g of magnesium acetate were dissolved in 30 mL of deionized water to prepare an impregnation solution with a total salt concentration of 0.15 mol / L. The molar ratio of strontium acetate to magnesium acetate was 1:1.

[0109] Figure 9 (a) and (b) are XRD patterns of the sample prepared in this embodiment in different diffraction angle ranges, respectively. It was observed that the main phase of the sample is zirconium oxide as the base component, and strontium titanate is also present. The main peak of strontium titanate (110) plane appears at around 32.4°, which proves the formation of strontium titanate. At the same time, compared with the standard peak of strontium titanate in Example 1, the diffraction peak of the (110) plane has shifted significantly to the large angle direction. This is because magnesium ions dissolve in strontium titanate and replace strontium, causing lattice distortion. This can indirectly prove the introduction of magnesium.

[0110] Figure 10 The cross-sectional SEM images, planar SEM images, corresponding EDS images, and relative elemental content diagrams of the sample prepared in this embodiment show that the strontium titanate modified layer of the sample is approximately 150–200 nm thick, and the surface is composed of nanoparticles of 20–60 nm. Among them, a large number of 20–30 nm nanoparticles exhibit ring-shaped agglomeration, and some 40–60 nm nanoparticles show sintering necks, but the degree of sintering is not high. The EDS images show that the sample surface contains elements such as strontium and magnesium, further confirming the formation of strontium titanate and the successful introduction of magnesium. The relative elemental content diagram specifically shows that the relative content of strontium in the strontium titanate modified layer of this sample is 2.84%, and the relative content of magnesium is 4.51%.

[0111] Figure 11 Images of the apparent contact angles of the sample prepared in this embodiment and the unmodified zirconia show that the apparent contact angle of the zirconia sample modified with a magnesium-solution strontium titanate layer (26.4°) is much smaller than that of the unmodified zirconia sample (62.3°). This indicates that the magnesium-solution strontium titanate modification layer can significantly improve the hydrophilicity of the zirconia surface, which is beneficial for the adsorption of proteins and the adhesion and proliferation of osteoblasts in the early stages of implantation.

[0112] Example 10

[0113] The preparation process is basically the same as in Example 9, except for step 3):

[0114] Dissolve 0.61 g of strontium acetate and 0.43 g of magnesium acetate in 30 mL of deionized water to prepare an impregnation solution with a total salt concentration of 0.2 mol / L. The molar ratio of strontium acetate to magnesium acetate is 1:1.

[0115] XRD and SEM characterization showed that the phase composition and morphology of the zirconium oxide modified with strontium titanate layer prepared in this example were basically the same as those in Example 9.

[0116] Example 11

[0117] The preparation process is basically the same as in Example 1, except for step 3):

[0118] Dissolve 0.31 g strontium acetate, 0.24 g calcium acetate and 0.21 g magnesium acetate in 30 mL of deionized water to prepare an impregnation solution with a total salt concentration of 0.15 mol / L. Add the three substances in equal molar amounts.

[0119] Figure 12 (a) and (b) are XRD patterns of the sample prepared in this embodiment in different diffraction angle ranges, respectively. It was observed that the main phase of the sample is zirconium oxide as the base component, and strontium titanate is also present. The main peak of strontium titanate (110) plane appears at around 32.4°, which proves the formation of strontium titanate. At the same time, compared with the standard peak of strontium titanate in Example 1, the diffraction peak of the (110) plane has shifted to a certain extent in the direction of large angle. This is due to the lattice distortion caused by the solid dissolution of calcium and magnesium ions in strontium titanate, which can indirectly prove the introduction of calcium and magnesium elements.

[0120] Figure 13 The cross-sectional SEM images, planar SEM images, corresponding EDS images, and relative elemental content diagrams of the sample prepared in this embodiment show that the strontium titanate modified layer of the sample is approximately 250 nm thick. The surface is composed of small particles with diameters of approximately 10–20 nm and large particles with diameters of approximately 50–100 nm. The two types of nanoparticles agglomerate and are tightly packed, exhibiting solid-phase sintering characteristics. The morphology is presumably caused by the co-solid solution of calcium and magnesium and local compositional inhomogeneity. The EDS images show that the sample surface contains elements such as strontium, calcium, and magnesium, further confirming the formation of strontium titanate and the successful introduction of calcium and magnesium elements. The relative elemental content diagram specifically shows that in the strontium titanate modified layer of this sample, the relative content of strontium is 2.61%, the relative content of calcium is 4.97%, and the relative content of magnesium is 1.91%.

[0121] Figure 14 Images of the apparent contact angles of the sample prepared in this embodiment and the unmodified zirconia show that the apparent contact angle of the zirconia sample modified with a calcium-magnesium solid solution strontium titanate layer (26.3°) is much smaller than that of the unmodified zirconia sample (62.3°). This indicates that the calcium-magnesium solid solution strontium titanate modification layer can significantly improve the hydrophilicity of the zirconia surface, which is conducive to the adsorption of proteins and the adhesion and proliferation of osteoblasts in the early stages of implantation.

[0122] Example 12

[0123] The preparation process is basically the same as in Example 11, except for step 3):

[0124] Dissolve 0.41 g strontium acetate, 0.32 g calcium acetate and 0.28 g magnesium acetate in 30 mL of deionized water to prepare an impregnation solution with a total salt concentration of 0.2 mol / L. Add the three substances in equal molar amounts.

[0125] XRD and SEM characterization showed that the phase composition and morphology of the zirconium oxide modified with strontium titanate layer prepared in this example were basically the same as those in Example 11.

[0126] Comparative Example 1

[0127] 1) Titanium sulfate and urea were dissolved in deionized water at a molar ratio of 1:3 to prepare a precursor solution A with a titanium sulfate concentration of 0.3 mol / L. Zirconia ceramic was placed in it and heated to boiling state for 15 min. Then the zirconia ceramic was taken out and kept at 900℃ for 30 min. A titanium dioxide film was successfully prepared on the surface of zirconia.

[0128] 2) Dissolve 0.92g of strontium acetate in 30mL of deionized water to obtain an impregnation solution with a concentration of 0.15mol / L. Place the zirconium oxide with the titanium dioxide film in the solution, let it stand for 24h, and then take it out and place it in a muffle furnace. Heat it to 700℃ at a heating rate of 1.5℃ / min and hold it at that temperature for 1h for heat treatment.

[0129] Figure 15 The XRD pattern and planar SEM image of the sample prepared for this comparative example show that the main phase of the sample is zirconium oxide as the base component. No strontium titanate diffraction peaks were observed. The surface morphology is composed of nanoparticles with a particle size of 30-50 nm. The particles are relatively loose and have many voids, making them easy to peel off.

[0130] Comparative Example 2

[0131] (1) Dissolve 1 mL of tetrabutyl titanate in 4 mL of anhydrous ethanol to prepare an ethanol solution of tetrabutyl titanate, and coat it on the surface of zirconia ceramic. Let it stand for 2 h, and after the tetrabutyl titanate reacts with water vapor in the air to hydrolyze and generate titanium dioxide, keep the zirconia at 900℃ for 30 min.

[0132] Steps (2-3) are exactly the same as in Example 1.

[0133] Figure 16 The planar SEM image of the sample prepared in this comparative example shows that nanoparticles with a particle size of 40-60 nm are dispersed on the surface of zirconia. However, the content of these nanoparticles is significantly low, and they do not completely and uniformly cover the zirconia surface to form a modification layer. Moreover, the structure is loose, resulting in a large area of ​​zirconia substrate being exposed.

[0134] Comparative Example 3

[0135] Steps (1-2) are exactly the same as in Example 1;

[0136] (3) Dissolve 0.4g of strontium acetate and 1.4g of sodium hydroxide in 40mL of deionized water, place the zirconium oxide treated in step (2) into it, put it into a polytetrafluoroethylene inner liner, seal it in a hydrothermal reactor, keep it at 200℃ for 24h, then take out the zirconium oxide and wash it three times with deionized water.

[0137] Figure 17 The planar SEM image of the sample prepared in this comparative example shows that nanoparticles with a particle size of 20-40 nm and their aggregates are scattered on the surface of zirconia. These nanoparticles failed to completely cover the surface of zirconia to form a modification layer, indicating that the preparation method failed.

[0138] Comparative Example 4

[0139] The preparation process is basically the same as in Example 1, except for step 2):

[0140] When the ratio of H2O2 solution to deionized water is changed to 3:1, the volume of the mixed solution remains 40 mL. At this time, the molar ratio of H2O2 aqueous solution to metatitanic acid is 7.8:1.

[0141] Figure 18 XRD patterns and planar SEM images of the sample prepared for this comparative example within different diffraction angle ranges were observed. It was found that the phase of the sample was zirconium oxide as the base component, and no obvious strontium titanate peak was observed. The main peak (110) of strontium titanate was also not observed near 32.4°, indicating that the amount of strontium titanate generated was too low and did not reach the XRD detection limit. Its surface was composed of nanoparticles with a size of 20-40 nm, and the aggregation state between the particles was relatively loose, making them easy to fall off.

[0142] Comparative Example 5

[0143] The preparation process is basically the same as in Example 1, except that strontium acetate in step 3) is replaced with strontium nitrate.

[0144] Figure 19 The planar SEM image of the sample prepared for this comparative example shows that its surface is composed of nanoparticles of 150-200 nm and nanoplates of 300-600 nm in size, with poor morphological uniformity. At the same time, the nanoplates cause more protrusions and sharp edges on the surface, which is not conducive to early cell adhesion.

[0145] Comparative Example 6

[0146] The preparation process is basically the same as in Example 1, except that the heating rate in step 3) is replaced with 5℃ / min.

[0147] Figure 20 The planar SEM image of the sample prepared in this comparative example shows that the strontium titanate layer is composed of nanoparticles with a particle size of 40-60 nm and intergranular glass phase regions with a size of 150-200 nm. There are many gaps between the particles, and the overall structure is relatively loose. The modified layer is easy to fall off from the zirconium oxide surface, resulting in failure.

[0148] The above-described embodiments are preferred embodiments, but the scope of protection of the present invention is not limited thereto. Those skilled in the art can easily understand the spirit of the present invention based on the above embodiments and make different extensions and variations, but as long as they do not depart from the spirit of the present invention, they are all within the scope of protection of the present invention.

Claims

1. A method for preparing a strontium titanate modified layer on a zirconium oxide surface based on an impregnation-heat treatment method, characterized in that, include: (1) Titanium sulfate, urea and water are mixed to obtain precursor liquid A. Zirconia ceramic is placed in precursor liquid A and heated to boiling state for a period of time. Then the zirconia ceramic is taken out and heat-treated A to obtain titanium dioxide film on the surface of zirconia. (2) Mix H2O2 aqueous solution, ammonia water and deionized water, add metatitanic acid and stir to dissolve to obtain precursor liquid B. Place the zirconium oxide with titanium dioxide film prepared in precursor liquid B and let it stand at room temperature for a period of time to deposit zirconium oxide modified with titanium dioxide precursor layer. Based on the number of moles of H2O2 in the H2O2 aqueous solution, the molar ratio of H2O2 aqueous solution to metatitanic acid is (3.7~5.2):1; (3) Strontium acetate, or a mixed salt of calcium acetate and / or magnesium acetate and strontium acetate, is dissolved in deionized water to obtain an impregnation solution. Zirconia modified with a titanium dioxide precursor layer is placed in the impregnation solution, allowed to stand for a period of time, and then taken out. After heat treatment B, a strontium titanate modified layer is prepared on the surface of the zirconia. The heat treatment B is performed at a temperature of 600-800℃, a holding time of 1-5h, and a heating rate of 1-3℃ / min.

2. The method for preparing a strontium titanate modified layer on a zirconium oxide surface based on the impregnation-heat treatment method according to claim 1, characterized in that, In step (1): The molar ratio of titanium sulfate to urea is 1:(1~7). The concentration of titanium sulfate in precursor fluid A is 0.1~1.0 mol / L.

3. The method for preparing a strontium titanate modified layer on a zirconium oxide surface based on the impregnation-heat treatment method according to claim 1, characterized in that, In step (1): Heat to boiling and maintain for 5-40 minutes; The heat treatment A is performed at a temperature of 800~1000℃ and a holding time of 10~60 min.

4. The method for preparing a strontium titanate modified layer on a zirconium oxide surface based on the impregnation-heat treatment method according to claim 1, characterized in that, In step (2): Based on the molar number of ammonium ions in ammonia water, the molar ratio of ammonia water to metatitanic acid is (2.0~2.4):1; The concentration of metatitanic acid in precursor fluid B is 0.02~0.20 g / mL.

5. The method for preparing a strontium titanate modified layer on a zirconium oxide surface based on the impregnation-heat treatment method according to claim 1, characterized in that, In step (2), the reaction is allowed to stand at room temperature for 6 to 48 hours.

6. The method for preparing a strontium titanate modified layer on a zirconium oxide surface based on the impregnation-heat treatment method according to claim 1, characterized in that, In step (3): The salt concentration in the impregnation solution is 0.05~0.5 mol / L.

7. The method for preparing a strontium titanate modified layer on a zirconium oxide surface based on the impregnation-heat treatment method according to claim 1, characterized in that, In step (3), the reaction is allowed to stand for 6 to 48 hours.

8. The method for preparing a strontium titanate modified layer on a zirconium oxide surface based on the impregnation-heat treatment method according to any one of claims 1 to 7, characterized in that: In step (1): The molar ratio of titanium sulfate to urea is 1:(3~7). The concentration of titanium sulfate in precursor fluid A is 0.3~1.0 mol / L; The heat treatment A is performed at a temperature of 850~950℃ and a holding time of 10~60 min. In step (2): The concentration of metatitanic acid in precursor fluid B is 0.07~0.12 g / mL; In step (3): The salt concentration in the impregnation solution is 0.15~0.2 mol / L; The heat treatment B is performed at a temperature of 700-800℃, a holding time of 1-2 hours, and a heating rate of 1.5-3.0℃ / min.

9. A zirconium oxide with a strontium titanate-modified layer on its surface, prepared by the method according to any one of claims 1 to 8.

10. The application of the zirconium oxide with a strontium titanate-modified layer as described in claim 9 in the field of biological implant materials.

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