A method for preparing a strontium titanate modification layer on the surface of zirconia based on the molten salt method, products and applications

Abstract

The application discloses a method for preparing a strontium titanate modification layer on the surface of zirconia based on a molten salt method, and comprises the following steps: (1) mixing titanium sulfate, urea and water to obtain precursor liquid A, placing zirconia ceramic in the precursor liquid A, heating to a boiling state and keeping for a period of time, taking out the zirconia ceramic, and preparing a titanium dioxide film on the surface of the zirconia ceramic after heat treatment A; (2) mixing H2O2 aqueous solution, ammonia and deionized water, adding metatitanic acid and stirring to dissolve, obtaining precursor liquid B, placing the zirconia ceramic with the titanium dioxide film prepared in the precursor liquid B, standing for a period of time in a room temperature environment, and depositing zirconia modified with a titanium dioxide precursor layer; (3) mixing a molten salt medium, strontium salt and an organic solvent into slurry, coating the slurry on the surface of the zirconia modified with the titanium dioxide precursor layer, and preparing a strontium titanate modification layer on the surface of the zirconia after heat treatment B. The strontium titanate layer prepared on the surface of the zirconia according to the method can be closely combined with the zirconia substrate, is non-toxic and non-corrosive to the human body, can introduce high content of Sr, Mg and Ca elements, and can release strontium ions, calcium ions and magnesium ions in the local implantation for a long time, so as to promote bone formation, promote the proliferation and differentiation of osteoblasts and the formation of new bone tissue, and improve the bone integration ability 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 the molten salt 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. In this method, a strontium titanate nanolayer coating is deposited on the surface of the zirconia implant using physical deposition. However, the resulting strontium titanate nanolayer coating has a thickness of up to 400 nm, while the Sr content in the coating is only 1.16 ± 0.18 at. 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 surface can bond tightly with the zirconia substrate and is non-toxic and non-corrosive to the human body. This method can introduce high levels of Sr, Mg, and Ca elements and can release strontium, calcium, and magnesium ions at the implantation site for a long period of time, thereby promoting bone formation, osteoblast proliferation and differentiation, and the formation of new bone tissue, thus improving the osseointegration capacity of the zirconia implant. This provides a new modification technology for the further application and development of zirconia in the field of 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 a molten salt 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) A slurry is made by mixing molten salt medium, strontium salt and organic solvent, and coated on the zirconium oxide surface modified with titanium dioxide precursor layer. After heat treatment B, a strontium titanate modified layer is prepared on the zirconium oxide surface.

[0011] The molten salt medium is selected from sodium chloride, or a mixture of sodium chloride and potassium chloride;

[0012] The strontium salt is selected from a single strontium salt, or a mixture of one or two of the calcium and magnesium salts with a strontium salt.

[0013] This invention first deposits two titanium dioxide layers on the surface of zirconia ceramic. Different preparation processes are used to impart different morphologies, structures, and reactivity to the two titanium dioxide layers. Then, a strontium titanate modified layer is constructed on the zirconia surface using a molten salt method. By varying the types of strontium salts introduced and the proportions of the molten salt medium, 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. The strontium titanate layer prepared by this method has high Sr, Mg, and Ca content. After implantation into the human body, it can release strontium ions, calcium ions, and magnesium ions at the affected site for a long period of time to promote the formation of new bone tissue, and its bone integration capacity is significantly improved.

[0014] Experiments revealed that if only one layer of titanium dioxide is deposited, the amount of strontium titanate generated is too small, and the molten salt medium will corrode the zirconium oxide substrate; however, if the source of the titanium dioxide precursor layer is changed and metatitanic acid is replaced with tetrabutyl titanate, the titanium dioxide precursor layer cannot be deposited.

[0015] In step (1):

[0016] 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.

[0017] Preferred:

[0018] The molar ratio of titanium sulfate to urea is 1:(1-7), more preferably 1:(3-7).

[0019] The concentration of titanium sulfate in precursor fluid A is 0.1–1.0 mol / L, more preferably 0.3–1.0 mol / L.

[0020] In step (1), heat to boiling and maintain for 5 to 40 minutes to allow titanium to precipitate.

[0021] Preferably, the heat treatment A is performed at a temperature of 800–1000°C and a holding time of 10–60 min.

[0022] Further preferably, the heat treatment A is performed at a temperature of 850–950°C.

[0023] 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.

[0024] Preferred:

[0025] 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;

[0026] 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 strontium titanate formation rate, which in turn leads to crack defects in the zirconium oxide matrix material, affecting its mechanical properties and durability.

[0027] Preferred:

[0028] 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;

[0029] The concentration of metatitanic acid in precursor fluid B is 0.02–0.20 g / mL, more preferably 0.07–0.12 g / mL.

[0030] In step (2), the reaction is allowed to stand at room temperature for 6 to 48 hours.

[0031] In step (3):

[0032] The strontium salt is selected from strontium carbonate, the calcium salt is selected from calcium carbonate, and the magnesium salt is selected from magnesium carbonate.

[0033] Experiments revealed that molten salt medium provides liquid-phase reaction conditions at high temperatures, making it easier for titanium dioxide and carbonates to dissolve, dissociate, migrate, and react in this liquid-phase environment, thus better converting them into strontium titanate. Tests showed that the amount and crystallinity of the strontium titanate modified layer prepared by the molten salt method were both high, indicating that this method is more conducive to improving the crystal conversion rate and crystal growth degree.

[0034] The organic solvent is selected from one or more of methanol, ethanol, and acetone; preferably, it is low-toxicity ethanol.

[0035] Preferred:

[0036] The mass ratio of strontium salt to molten salt medium is (0.3-0.7):1; more preferably (0.5-0.6):1.

[0037] Preferably, the molten salt medium is selected from a mixture of sodium chloride and potassium chloride, and the mass ratio of sodium chloride to potassium chloride is (0.8~3.0):1. Experiments have shown that, compared with sodium chloride alone as the molten salt medium, the morphology uniformity of strontium titanate nanoparticles in the strontium titanate modified layer prepared by using a composite molten salt medium is higher.

[0038] Further preferred, the mass ratio of sodium chloride to potassium chloride is (0.8-1.2):1.

[0039] Preferably, the heat treatment B is performed at a temperature of 800–1000°C for 1–5 hours; more preferably, the heat treatment temperature is 800–900°C for 1–2 hours.

[0040] The present invention also discloses zirconium oxide with a strontium titanate modified layer on its surface prepared according to the above method.

[0041] The strontium titanate layer prepared by this invention (with only strontium as the introduced alkaline earth metal element) is a layer of nanoparticles uniformly distributed on the surface of zirconium oxide, with a layer thickness of about 150 nm, wherein the particle size of the constituent unit nanoparticles is 10-100 nm.

[0042] The strontium titanate layer (with the simultaneous introduction of calcium and magnesium elements) prepared by this invention is a layer of nanoparticles uniformly distributed on the surface of zirconium oxide, with a layer thickness of about 150-250 nm. Experiments revealed that when strontium and calcium were introduced, the strontium titanate layer thickness was approximately 150 nm, composed of bulk grains ranging from 0.4 to 1.5 μm. This was due to the introduced calcium entering the strontium titanate lattice in a solid solution form, causing lattice distortion and abnormal crystal growth. When strontium and magnesium were introduced, the strontium titanate layer thickness was also approximately 150 nm, composed of irregular polyhedral particles with sizes ranging from 100 to 300 nm, exhibiting high surface roughness. This was also caused by magnesium dissolving in the strontium titanate crystals. When strontium, calcium, and magnesium were introduced simultaneously, the strontium titanate layer thickness was approximately 200 to 400 nm, composed of tetragonal nanoparticles with sizes ranging from 150 to 400 nm along the planar direction. The structure of this strontium titanate composition was simultaneously affected by the solid solution of calcium and magnesium.

[0043] The present invention also discloses the application of the zirconium oxide with a strontium titanate-modified surface in the field of bio-implant materials.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] This invention discloses a method for constructing a strontium titanate modified layer on the surface of a zirconia implant. A layer of strontium titanate nanoparticles is prepared on the zirconia surface by a molten salt method. By controlling the proportion of the molten salt medium and the types of active osteogenic elements introduced, the composition and morphology of the strontium titanate layer are controlled. Finally, a strontium titanate layer that is tightly bonded to the substrate, completely covers it, has a uniform morphology, and has controllable composition is prepared on the zirconia surface.

[0046] This invention involves preparing a strontium titanate modification layer on the surface of zirconia, introducing a large amount of osteogenic elements such as strontium, calcium, and magnesium into the zirconia surface. After implantation, this modification layer continuously releases strontium, calcium, and magnesium ions into the bone defect site to promote bone formation and repair, thereby improving the osseointegration capacity of the zirconia implant. Strontium titanate and calcium and magnesium elements are non-toxic and non-corrosive to the human body, posing low safety risks. They are also relatively stable, not easily decomposed or deformed, and can exist for a long time in the complex human body environment. Their introduction and modification have been applied in other artificial bone repair materials such as titanium metal implants, and their biocompatibility and osteogenic properties have been fully verified. In summary, the strontium titanate modification layer can promote bone formation and regeneration at the implant site by introducing osteogenic ions such as strontium, calcium, and magnesium ions into the zirconia implant surface, ultimately improving the osseointegration capacity, implantation success rate, and treatment effect of the zirconia implant, thus expanding the application of zirconia ceramics in the field of implants. Attached Figure Description

[0047] Figure 1 The image shows a SEM image of the zirconium oxide with a titanium dioxide film prepared in step 1) of Example 1.

[0048] 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.

[0049] Figure 3 The XRD pattern of the strontium titanate modified layer on the zirconium oxide surface prepared in Example 1;

[0050] Figure 4 SEM images of cross sections, SEM images of planar sections, EDS images of the strontium titanate modified layer on the zirconium oxide surface prepared in Example 1, and a graph showing the relative elemental contents.

[0051] Figure 5 SEM image of the strontium titanate modified layer on the zirconium oxide surface prepared in Example 6;

[0052] Figure 6 The XRD pattern of the strontium titanate modified layer on the zirconium oxide surface prepared in Example 9;

[0053] Figure 7 SEM images of cross sections, planar SEM images, EDS images, and relative elemental content diagrams of the strontium titanate modified layer on the zirconium oxide surface prepared in Example 9;

[0054] Figure 8 The XRD pattern of the strontium titanate modified layer on the zirconium oxide surface prepared in Example 11;

[0055] Figure 9 Cross-sectional SEM images, planar SEM images, EDS images, and relative elemental content diagrams of the strontium titanate modified layer on the zirconium oxide surface prepared in Example 11;

[0056] Figure 10 The XRD pattern of the strontium titanate modified layer on the zirconium oxide surface prepared in Example 13;

[0057] Figure 11 Cross-sectional SEM images, planar SEM images, EDS images, and relative elemental content diagrams of the strontium titanate modified layer on the zirconium oxide surface prepared in Example 13;

[0058] Figure 12 XRD pattern and planar SEM image of the strontium titanate modified layer on the zirconia surface prepared in Comparative Example 1;

[0059] Figure 13 A planar SEM image of the strontium titanate modified layer on the zirconium oxide surface prepared in Comparative Example 3;

[0060] Figure 14This is a planar SEM image of the strontium titanate modified layer on the zirconium oxide surface prepared for Comparative Example 4. Detailed Implementation

[0061] 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.

[0062] Example 1

[0063] 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.

[0064] 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 particles with a particle size of 30-45 nm.

[0065] 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.

[0066] 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.

[0067] 3) Weigh 0.8g of sodium chloride and 1.0g of potassium chloride at a mass ratio of 0.8:1 to obtain 1.8g of molten salt medium. Then weigh 0.9g of strontium carbonate at a mass ratio of 0.5:1 for strontium salt to molten salt medium. Mix and grind the strontium carbonate with the molten salt medium until there is no obvious particle feel. Add a small amount of anhydrous ethanol to grind into a slurry. Coat the slurry onto the zirconium oxide surface modified with a titanium dioxide precursor layer and keep it at 850℃ for 2 hours. Finally, a strontium titanate modified layer is prepared on the zirconium oxide surface.

[0068] 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.

[0069] 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, composed of 30–50 nm nanoparticles, and has a relatively smooth surface. 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 content of strontium in the strontium titanate modified layer of this sample is 9.88 at% (unless otherwise specified, the elemental relative content in this invention refers to atomic content).

[0070] Example 2

[0071] The preparation process is basically the same as in Example 1, except for step 2):

[0072] If the volume ratio of H2O2 aqueous solution to deionized water is changed to 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.

[0073] 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.

[0074] Example 3

[0075] The preparation process is basically the same as in Example 1, except for step 2):

[0076] The amount of metatitanic acid added was replaced with 4.8g to obtain a precursor solution with a concentration of 0.12g / mL. At this time, the molar ratio of H2O2 aqueous solution to metatitanic acid was 5.2:1.

[0077] 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.

[0078] Example 4

[0079] The preparation process is basically the same as in Example 1, except for step 3):

[0080] Weigh out 0.9g of sodium chloride and 0.9g of potassium chloride in a 1:1 mass ratio and mix them to obtain 1.8g of molten salt medium.

[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 5

[0083] The preparation process is basically the same as in Example 1, except for step 3):

[0084] Weigh out 0.98g of sodium chloride and 0.82g of potassium chloride in a mass ratio of 1.2:1 and mix them to obtain 1.8g of molten salt medium.

[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 6

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

[0088] Weigh out 1.35g of sodium chloride and 0.45g of potassium chloride in a mass ratio of 3:1 and mix them to obtain 1.8g of molten salt medium.

[0089] Figure 5 The planar SEM image of the sample prepared in this embodiment shows that the sample is composed of nanoparticles with a particle size of 10-100 nm, and the morphological uniformity is slightly poor.

[0090] Example 7

[0091] The preparation process is basically the same as in Example 1, except for step 3):

[0092] 1.8g of sodium chloride was added as the molten salt medium; no potassium chloride was added.

[0093] SEM characterization showed that the morphology of the strontium titanate layer prepared in this example was similar to that in Example 6.

[0094] Example 8

[0095] The preparation process is basically the same as in Example 1, except for step 3):

[0096] Replace the mass of strontium carbonate with 1.08g, at which point the mass ratio of strontium salt to molten salt medium is 0.6:1.

[0097] 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.

[0098] Example 9

[0099] The preparation process is basically the same as in Example 1, except for step 3):

[0100] Replace 0.9g of strontium carbonate with a mixed salt consisting of 0.45g of strontium carbonate and 0.45g of calcium carbonate.

[0101] 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 (110) plane of strontium titanate appears near 33.0°, which proves the formation of strontium titanate and shows that the solid solution doping of calcium ions causes lattice distortion of strontium titanate, causing the diffraction peak to shift to the larger angle direction.

[0102] Figure 7 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 modification layer of the sample is approximately 150 nm thick and consists of large grains of 0.4–1.5 μm along the planar direction, exhibiting high surface roughness. The EDS images indicate that the sample surface contains elements such as strontium and calcium, further confirming the presence of strontium titanate and the strontium titanate lattice distortion caused by calcium ion solid solution. The relative elemental content diagram specifically shows that in this strontium titanate modification layer, the relative content of strontium is 3.18%, and the relative content of calcium is 9.78%.

[0103] Example 10

[0104] The preparation process is basically the same as in Example 9, except for step 3):

[0105] When the mass of both strontium carbonate and calcium carbonate is replaced to 0.54g, the total mass of strontium salt is 1.08g, and the mass ratio of strontium salt to molten salt medium is 0.6:1.

[0106] 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 9.

[0107] Example 11

[0108] The preparation process is basically the same as in Example 1, except for step 3):

[0109] Replace 0.9g of strontium carbonate with a mixed salt consisting of 0.45g of strontium carbonate and 0.45g of magnesium carbonate.

[0110] Figure 8(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) plane of strontium titanate appears to the left of 32.4°, which proves the formation of strontium titanate and shows that the solid solution doping of magnesium ions causes lattice distortion of strontium titanate, causing the diffraction peak to shift to a smaller angle direction.

[0111] Figure 9 The cross-sectional SEM image, planar SEM image, corresponding EDS image, and elemental relative content diagram of the sample prepared in this embodiment are shown. It is observed that the strontium titanate modification layer of the sample is about 150 nm thick and is formed by irregular polyhedral nanocrystals of 100-300 nm, resulting in a high surface roughness of the modification layer. The EDS image shows that the sample surface contains elements such as strontium and magnesium, further confirming the presence of strontium titanate and the strontium titanate lattice distortion caused by magnesium ion solid solution. The elemental relative content diagram specifically shows that in this strontium titanate modification layer, the relative content of strontium is 5.38% and the relative content of magnesium is 1.05%.

[0112] Example 12

[0113] The preparation process is basically the same as in Example 11, except for step 3):

[0114] When the mass of both strontium carbonate and magnesium carbonate is replaced to 0.54g, the total mass of strontium salt is 1.08g, and the mass ratio of strontium salt to molten salt medium is 0.6:1.

[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 11.

[0116] Example 13

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

[0118] Replace 0.9g of strontium carbonate with a mixed salt consisting of 0.3g of strontium carbonate, 0.3g of calcium carbonate, and 0.3g of magnesium carbonate.

[0119] Figure 10 (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 (110) plane of strontium titanate appears at around 32.5°, which proves the formation of strontium titanate and shows that the simultaneous solid solution doping of calcium and magnesium elements causes lattice distortion of strontium titanate, causing the diffraction peak to shift to the larger angle direction.

[0120] Figure 11The 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 200–400 nm thick and consists of tetragonal nanocrystals of 150–400 nm along the planar direction, exhibiting high surface roughness. The EDS images indicate that the sample surface contains elements such as strontium, calcium, and magnesium, further confirming the presence of strontium titanate and the lattice distortion of strontium titanate caused by the co-solution of calcium and magnesium ions. The relative elemental content diagram specifically shows that in this strontium titanate modified layer, the relative content of strontium is 0.95%, the relative content of calcium is 7.09%, and the relative content of magnesium is 1.11%.

[0121] Example 14

[0122] The preparation process is basically the same as in Example 13, except for step 3):

[0123] When the mass of strontium carbonate, calcium carbonate, and magnesium carbonate is replaced with 0.36g each, the total mass of strontium salt is 1.08g, and the mass ratio of strontium salt to molten salt medium is 0.6:1.

[0124] 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 13.

[0125] Comparative Example 1

[0126] 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.

[0127] 2) Weigh 0.8g of sodium chloride and 1.0g of potassium chloride in a mass ratio of 0.8:1 to obtain 1.8g of molten salt medium. Then weigh 0.9g of strontium carbonate in a mass ratio of 0.5:1 for strontium salt to molten salt medium. Mix and grind the strontium carbonate with the molten salt medium until there is no obvious particle feel. Add a small amount of anhydrous ethanol to grind into a slurry. Coat the slurry onto the zirconium oxide surface modified with titanium dioxide film and keep it at 850℃ for 2h. Finally, a strontium titanate modified layer is prepared on the zirconium oxide surface.

[0128] Figure 12The XRD pattern and planar SEM image of the sample prepared for this comparative example show that although strontium titanate is present in the phase of the sample, large cracks and defects appear on the surface of its modified layer. Furthermore, the zirconia substrate is corroded by molten salt, and large particles are pulverized into small particles. This can easily lead to crack defects in the zirconia matrix material, affecting its mechanical properties and durability. This may be because the titanium dioxide precursor layer was not deposited, resulting in a relatively excessive amount of molten salt, which then penetrates into the surface of the zirconia substrate.

[0129] Comparative Example 2

[0130] Step (1) is exactly the same as in Example 1;

[0131] (2) Dissolve 1 mL of tetrabutyl titanate in 4 mL of anhydrous ethanol to prepare an ethanol solution of tetrabutyl titanate, and coat it onto the zirconium oxide ceramic surface treated in step (1). Let it stand for 2 h to allow the tetrabutyl titanate to react with water vapor in the air and hydrolyze to generate titanium dioxide.

[0132] Step (3) is exactly the same as in Example 1.

[0133] XRD and SEM characterization showed that the phase composition and morphology of the zirconium oxide modified with strontium titanate layer prepared in this embodiment were basically the same as those in Comparative Example 1. This may be because the amount of titanium dioxide precursor deposited by the hydrolysis of tetrabutyl titanate was too small.

[0134] Comparative Example 3

[0135] The preparation process is basically the same as in Example 1, except for step 2):

[0136] 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.

[0137] Figure 13 The planar SEM image of the sample prepared in this comparative example shows that the morphology of the sample is similar to that of Comparative Example 1. The zirconia particles are also corroded and pulverized by molten salt to form small particles, which is not conducive to the stability and durability of the zirconia substrate. This may be because the amount of hydrogen peroxide is too large, which inhibits the deposition of titanium dioxide precursor and leads to a decrease in the amount of titanium dioxide deposited.

[0138] Comparative Example 4

[0139] The preparation process is basically the same as in Example 1, except for step 3):

[0140] Weigh out 0.45g of sodium chloride and 1.35g of potassium chloride in a mass ratio of 1:3 and mix them to obtain 1.8g of molten salt medium.

[0141] Figure 14 The planar SEM image of the sample prepared for this comparative example shows that the strontium titanate modified layer consists of nanoparticles of 10–30 nm in size, accompanied by relatively obvious interparticle sintering, and some large crystal particles with a size of about 200–300 nm appear. The surface morphology is uneven and contains defects, which is not conducive to practical applications.

[0142] Comparative Example 5

[0143] The preparation process is basically the same as in Example 1, except for step 3):

[0144] 1.8g of potassium chloride was added as the molten salt medium; no sodium chloride was added.

[0145] SEM characterization showed that the morphology of the strontium titanate layer prepared in this comparative example was similar to that in comparative example 4.

[0146] 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 a molten salt 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. 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. The molar ratio of titanium sulfate to urea is 1:(1~7). The concentration of titanium sulfate in precursor fluid A is 0.3~1.0 mol / L; (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 6~48 h 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; 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; (3) A slurry is prepared by mixing molten salt medium, strontium salt and organic solvent, and coating it on the surface of zirconium oxide modified with titanium dioxide precursor layer. After heat treatment B, a strontium titanate modified layer is prepared on the zirconium oxide surface. The molten salt medium is selected from a mixture of sodium chloride and potassium chloride, and the mass ratio of sodium chloride to potassium chloride is (0.8~1.2):

1. The strontium salt is selected from a single strontium salt, or a mixture of one or two of the calcium and magnesium salts with a strontium salt; The strontium salt is selected from strontium carbonate, the calcium salt is selected from calcium carbonate, and the magnesium salt is selected from magnesium carbonate. The mass ratio of strontium salt to molten salt medium is (0.3~0.7):1; The heat treatment B is performed at a temperature of 800~1000℃ for a holding time of 1~5h.

2. The method for preparing a strontium titanate modified layer on a zirconium oxide surface based on the molten salt method according to claim 1, characterized in that, In step (3), the organic solvent is selected from one or more of methanol, ethanol, and acetone.

3. The method for preparing a strontium titanate modified layer on a zirconium oxide surface based on the molten salt method according to any one of claims 1 to 2, characterized in that: In step (1): The molar ratio of titanium sulfate to urea is 1:(3~7). 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 mass ratio of strontium salt to molten salt medium is (0.5~0.6):1; The heat treatment B is performed at a temperature of 800-900℃ for 1-2 hours.

4. A zirconium oxide with a strontium titanate-modified layer on its surface, prepared by the method according to any one of claims 1 to 3.

5. The application of the zirconium oxide with a strontium titanate-modified layer as described in claim 4 in the field of biological implant materials.

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