Method for hydrothermally generating nano-zinc oxide / hydroxyapatite composite coating on cold-sprayed zinc coating

Abstract

The invention relates to the technical field of medical materials, in particular to a method for hydrothermally generating a nano-zinc oxide / hydroxyapatite composite coating on a cold spraying zinc coating. Zinc powder is cold-sprayed on the surface of a metal matrix to form a zinc coating, and a first intermediate is obtained; placing the first intermediate above the liquid level of a sodium hydroxide solution, and carrying out a first hydrothermal reaction to form a nano-zinc oxide coating so as to obtain a second intermediate; and placing the second intermediate in a mixed solution of disodium calcium ethylene diamine tetraacetate and monopotassium phosphate, and carrying out a second hydrothermal reaction to generate nano-hydroxyapatite so as to obtain the nano-zinc oxide / hydroxyapatite composite coating. The nano-zinc oxide / hydroxyapatite composite coating prepared by the method has good biological properties, is firmly combined with a matrix, and is not easy to crack or peel off.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of medical materials, in particular to a method for hydrothermally generating a nano zinc oxide / hydroxyapatite composite coating on a cold-sprayed zinc coating. BACKGROUND

[0002] Hydroxyapatite has similar material composition to the inorganic matter of human hard tissue, has good biological activity and biocompatibility, can provide a similar microenvironment to natural bone, form phosphate for biological mineralization, and is a kind of bioactive material widely used in bone repair and regeneration. Nano zinc oxide has good biocompatibility with biological tissue, can be naturally decomposed, has low harm to the human body, and has significant antibacterial effect on bacteria. The nano zinc oxide and hydroxyapatite form a composite coating, which can integrate the advantages of both.

[0003] Nano zinc oxide / hydroxyapatite composite coatings can be prepared on the surface of a substrate by mixing particle plasma spraying, sol-gel method, coprecipitation method, hydrothermal method and electrophoretic deposition method. The hydrothermal method can be carried out under relatively mild and simple process, thereby reducing unnecessary side reactions and the formation of by-products, which helps to generate high-purity, well-crystallized zinc oxide and hydroxyapatite. The preparation of nano zinc oxide coating on the surface of the substrate requires zinc source, usually inorganic zinc salt, organic zinc compound, zinc oxide particles and zinc thin film prepared by physical vapor deposition. So far, there has been no report on the hydrothermal method for generating zinc oxide / hydroxyapatite composite coating on the cold-sprayed zinc coating. SUMMARY

[0004] The present application provides a method for hydrothermally generating a nano zinc oxide / hydroxyapatite composite coating on a cold-sprayed zinc coating. The present application provides a new preparation method, and the nano zinc oxide / hydroxyapatite composite coating prepared by the method of the present application has good biological performance.

[0005] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions:

[0006] The present application provides a method for hydrothermally generating a nano zinc oxide / hydroxyapatite composite coating on a cold-sprayed zinc coating, comprising the following steps: cold-spraying zinc powder on the surface of a metal substrate to form a zinc coating, obtaining a first intermediate;

[0007] The first intermediate is placed above the liquid surface of a sodium hydroxide solution to perform a first hydrothermal reaction, forming a nano zinc oxide coating, obtaining a second intermediate;

[0008] The second intermediate is placed in a mixed solution of calcium disodium ethylenediaminetetraacetate and potassium dihydrogen phosphate to perform a second hydrothermal reaction to generate nano-hydroxyapatite, thereby obtaining a nano-zinc oxide / hydroxyapatite composite coating; the pH value of the mixed solution of calcium disodium ethylenediaminetetraacetate and potassium dihydrogen phosphate is 7-13.

[0009] Preferably, the thickness of the zinc coating is greater than 10 μm.

[0010] Preferably, the concentration of the sodium hydroxide solution is 0.5-3 mol / L.

[0011] Preferably, the temperature of the first hydrothermal reaction is 80-170 ℃.

[0012] Preferably, the time of the first hydrothermal reaction is 6-36 h.

[0013] Preferably, the molar ratio of calcium disodium ethylenediaminetetraacetate to potassium dihydrogen phosphate is 1.66-1.67:1.

[0014] Preferably, in the mixed solution of calcium disodium ethylenediaminetetraacetate and potassium dihydrogen phosphate, the concentration of calcium disodium ethylenediaminetetraacetate is 0.05-0.60 mol / L, and the concentration of potassium dihydrogen phosphate is 0.05-0.50 mol / L.

[0015] Preferably, the temperature of the second hydrothermal reaction is 70-180 ℃.

[0016] Preferably, the time of the second hydrothermal reaction is 6-36 h.

[0017] Preferably, the metal substrate comprises AZ91D magnesium alloy.

[0018] The application provides a method for hydrothermally generating a nano-zinc oxide / hydroxyapatite composite coating from a cold-sprayed zinc coating, comprising the following steps: cold-spraying zinc powder on the surface of a metal substrate to form a zinc coating, thereby obtaining a first intermediate; placing the first intermediate above the liquid surface of a sodium hydroxide solution to perform a first hydrothermal reaction to form a nano-zinc oxide coating, thereby obtaining a second intermediate; placing the second intermediate in a mixed solution of calcium disodium ethylenediaminetetraacetate and potassium dihydrogen phosphate to perform a second hydrothermal reaction to generate nano-hydroxyapatite, thereby obtaining a nano-zinc oxide / hydroxyapatite composite coating; and the pH value of the mixed solution of calcium disodium ethylenediaminetetraacetate and potassium dihydrogen phosphate is 7-13.

[0019] In addition, the zinc coating sprayed on the surface of the metal substrate can not only serve as a Zn source for the subsequent nano-zinc oxide coating, but also serve as a transition layer between the zinc oxide / hydroxyapatite composite coating and the substrate, thereby mitigating the mismatch in mechanical properties between the substrate and the composite coating and avoiding cracking or peeling of the composite coating on the surface of the metal substrate. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 Surface morphology of the nano-zinc oxide / hydroxyapatite composite coating obtained in Example 1 (left) and surface morphology of the nano-zinc oxide / hydroxyapatite composite coating obtained in Example 1 after immersion in Hanks' simulated body fluid for 14 days (right);

[0021] Figure 2 Surface morphology (left) and energy spectrum (right) of the nano-zinc oxide / hydroxyapatite composite coating obtained in Example 1 after immersion;

[0022] Figure 3 Cross-sectional morphology (left) and energy spectrum (right) of the nano-zinc oxide / hydroxyapatite composite coating obtained in Example 1;

[0023] Figure 4 Phase structure pattern of the coating obtained in each step of Example 1 and the nano-zinc oxide / hydroxyapatite composite coating after immersion;

[0024] Figure 5 Surface morphology of the nano-zinc oxide / hydroxyapatite composite coating obtained in Example 2 (left) and surface morphology of the nano-zinc oxide / hydroxyapatite composite coating obtained in Example 2 after immersion in Hanks' simulated body fluid for 14 days (right);

[0025] Figure 6 Surface morphology (left) and energy spectrum (right) of the nano-zinc oxide / hydroxyapatite composite coating obtained in Example 2 after immersion;

[0026] Figure 7 Cross-sectional morphology (left) and energy spectrum (right) of the nano-zinc oxide / hydroxyapatite composite coating obtained in Example 2;

[0027] Figure 8 Phase structure pattern of the coating obtained in each step of Example 2 and the nano-zinc oxide / hydroxyapatite composite coating after immersion;

[0028] Figure 9 Surface morphology of the nano-zinc oxide / hydroxyapatite composite coating obtained in Example 3 (left) and surface morphology of the nano-zinc oxide / hydroxyapatite composite coating obtained in Example 3 after immersion in Hanks' simulated body fluid for 14 days (right);

[0029] Figure 10 Surface morphology (left) and energy spectrum (right) of the nano-zinc oxide / hydroxyapatite composite coating obtained in Example 3 after immersion;

[0030] Figure 11 Cross-sectional morphology (left) and energy dispersive spectroscopy (right) of the nano zinc oxide / hydroxyapatite composite coating obtained in Example 3;

[0031] Figure 12 Phase structure pattern of the coating obtained in each step of Example 3 and the nano zinc oxide / hydroxyapatite composite coating after immersion;

[0032] Figure 13 Surface morphology (left) of the nano zinc oxide / hydroxyapatite composite coating obtained in Example 4 and surface morphology (right) thereof after immersion in Hanks' simulated body fluid for 14 days;

[0033] Figure 14 Surface morphology (left) and energy dispersive spectroscopy (right) of the nano zinc oxide / hydroxyapatite composite coating obtained in Example 4 after immersion;

[0034] Figure 15 Cross-sectional morphology (left) and energy dispersive spectroscopy (right) of the nano zinc oxide / hydroxyapatite composite coating obtained in Example 4;

[0035] Figure 16 Phase structure pattern of the coating obtained in each step of Example 4 and the nano zinc oxide / hydroxyapatite composite coating after immersion;

[0036] Figure 17 Surface morphology (left) of the nano zinc oxide / hydroxyapatite composite coating obtained in Example 5 and surface morphology (right) thereof after immersion in Hanks' simulated body fluid for 14 days;

[0037] Figure 18 Surface morphology (left) and energy dispersive spectroscopy (right) of the nano zinc oxide / hydroxyapatite composite coating obtained in Example 5 after immersion;

[0038] Figure 19 Cross-sectional morphology (left) and energy dispersive spectroscopy (right) of the nano zinc oxide / hydroxyapatite composite coating obtained in Example 5;

[0039] Figure 20 Phase structure pattern of the coating obtained in each step of Example 5 and the nano zinc oxide / hydroxyapatite composite coating after immersion;

[0040] Figure 21 Surface morphology (left) of the AZ91D magnesium alloy in Comparative Example 1 and surface morphology (right) thereof after immersion in Hanks' simulated body fluid for 14 days;

[0041] Figure 22 Surface morphology (left) and energy dispersive spectroscopy (right) of the AZ91D magnesium alloy in Comparative Example 1 after immersion;

[0042] Figure 23Cross-sectional morphology (left) and energy spectrum (right) of AZ91D magnesium alloy in Example 1;

[0043] Figure 24 Phase structure pattern of AZ91D magnesium alloy in Example 1;

[0044] Figure 25 Surface morphology pattern of zinc coating obtained in Comparative Example 2 (left) and surface morphology pattern after immersion in Hanks' simulated body fluid for 14 days (right);

[0045] Figure 26 Surface morphology (left) and energy spectrum (right) of zinc coating obtained in Comparative Example 2 after immersion;

[0046] Figure 27 Cross-sectional morphology (left) and energy spectrum (right) of zinc coating obtained in Comparative Example 2 after immersion;

[0047] Figure 28 Phase structure pattern of zinc coating obtained in Comparative Example 2 before and after immersion;

[0048] Figure 29 Surface morphology pattern of Comparative Example 3 (left) and surface morphology pattern after immersion in Hanks' simulated body fluid for 14 days (right);

[0049] Figure 30 Surface morphology (left) and energy spectrum (right) of Comparative Example 3 after immersion;

[0050] Figure 31 Cross-sectional morphology (left) and energy spectrum (right) of Comparative Example 3;

[0051] Figure 32 Phase structure pattern of coating obtained in each step of Comparative Example 3 and nano-zinc oxide coating after immersion;

[0052] Figure 33 Surface morphology pattern of zinc / hydroxyapatite composite coating obtained in Comparative Example 4 (left) and surface morphology pattern after immersion in Hanks' simulated body fluid for 14 days (right);

[0053] Figure 34 Surface morphology (left) and energy spectrum (right) of zinc / hydroxyapatite composite coating obtained in Comparative Example 4 after immersion;

[0054] Figure 35 Cross-sectional morphology (left) and energy spectrum (right) of zinc / hydroxyapatite composite coating obtained in Comparative Example 4;

[0055] Figure 36 Phase structure pattern of coating obtained in each step of Comparative Example 4 and zinc / hydroxyapatite composite coating after immersion. DETAILED DESCRIPTION

[0056] The present application provides a method for preparing a nano zinc oxide / hydroxyapatite composite coating by hydrothermal reaction of a cold-sprayed zinc coating, comprising the following steps:

[0057] Spraying zinc powder on the surface of a metal substrate to form a zinc coating, thereby obtaining a first intermediate;

[0058] Placing the first intermediate above the liquid level of a sodium hydroxide solution to perform a first hydrothermal reaction, thereby forming a nano zinc oxide coating, and obtaining a second intermediate;

[0059] Placing the second intermediate in a mixed solution of calcium disodium ethylenediaminetetraacetate and potassium dihydrogen phosphate to perform a second hydrothermal reaction, thereby generating nano hydroxyapatite, and obtaining a nano zinc oxide / hydroxyapatite composite coating; the pH value of the mixed solution of calcium disodium ethylenediaminetetraacetate and potassium dihydrogen phosphate is 7-13.

[0060] In the present application, unless otherwise specified, all raw materials used are commercially available products well known in the art.

[0061] The present application sprays zinc powder on the surface of a metal substrate to form a zinc coating, thereby obtaining a first intermediate.

[0062] The present application does not have special requirements for the metal substrate, and all metal substrates well known in the art can be used, such as AZ91D magnesium alloy.

[0063] The present application does not have special requirements for the conditions of cold spraying, and uniform zinc coating can be formed using the cold spraying conditions well known in the art. In the present application, the thickness of the zinc coating is preferably greater than 10 μm, and more preferably 50-1500 μm, and in specific embodiments, can be 50, 100, 300, 500, 800, 1000, 1200 or 1500 μm.

[0064] After obtaining the first intermediate, the present application places the first intermediate above the liquid level of a sodium hydroxide solution (the first intermediate does not contact the sodium hydroxide solution) to perform a first hydrothermal reaction, thereby forming a nano zinc oxide coating, and obtaining a second intermediate.

[0065] The present application does not have special requirements for the distance between the first intermediate and the liquid level of the sodium hydroxide solution, and in the embodiments of the present application, the distance is about 20 mm. Through preliminary experiments, the present application found that placing the sample in a sodium hydroxide solution to perform a hydrothermal reaction did not generate a nano zinc oxide coating on the surface of the coating or generated a nano zinc oxide coating that was not ideal under different hydrothermal conditions. Therefore, the present application places the first intermediate above the liquid level of a sodium hydroxide solution to perform a first hydrothermal reaction.

[0066] In the present application, the concentration of the sodium hydroxide solution is preferably 0.5-3 mol / L, and in specific embodiments can be 0.5, 1, 1.5, 2, 2.5 or 3 mol / L.

[0067] In the present application, the temperature of the first hydrothermal reaction is preferably 80-170℃, and in specific embodiments can be 80, 100, 110, 120, 130, 140, 150, 160 or 170℃; the time of the first hydrothermal reaction is preferably 6-36 h, and in specific embodiments can be 8, 12, 16, 20, 24, 28, 32 or 36 h. In the present application, the zinc coating in the first intermediate reacts with sodium hydroxide to form a nano-zinc oxide coating during the first hydrothermal reaction.

[0068] After obtaining the second intermediate, the present application places the second intermediate in a mixed solution of calcium disodium ethylenediaminetetraacetate and potassium dihydrogen phosphate to perform a second hydrothermal reaction to generate nano-hydroxyapatite, thereby obtaining a nano-zinc oxide / hydroxyapatite composite coating.

[0069] In the present application, the molar ratio of calcium disodium ethylenediaminetetraacetate and potassium dihydrogen phosphate is preferably 1.66-1.67:1, and the present application controls the molar ratio of the two to facilitate the generation of hydroxyapatite. In the present application, the concentration of calcium disodium ethylenediaminetetraacetate in the mixed solution of calcium disodium ethylenediaminetetraacetate and potassium dihydrogen phosphate is preferably 0.05-0.60 mol / L, and in specific embodiments can be 0.05, 0.1, 0.2, 0.25, 0.3, 0.4, 0.5 or 0.6 mol / L.

[0070] In the present application, the pH value of the mixed solution of calcium disodium ethylenediaminetetraacetate and potassium dihydrogen phosphate is preferably 7-13, and in specific embodiments can be 8, 8.5, 10, 11, 12 or 13. Different pH values result in different crystallinities of the generated hydroxyapatite. In the present application, the zinc coating improves the corrosion resistance of the magnesium matrix, and a lower crystallinity of the hydroxyapatite often exhibits higher biological activity and faster degradation rate. When the pH value is 11, it is more conducive to the synthesis of hydroxyapatite.

[0071] In the present application, the calcium disodium ethylenediaminetetraacetate and potassium dihydrogen phosphate are preferably dissolved in water, and then sodium hydroxide is added to adjust the pH value to the target range.

[0072] In the present application, the temperature of the second hydrothermal reaction is preferably 70-180°C, and in specific embodiments can be 70, 80, 100, 110, 120, 130, 140, 150, 160, 170 or 180°C; the time of the first hydrothermal reaction is preferably 6-36h, and in specific embodiments can be 8, 12, 16, 20, 24, 28, 32 or 36h. In the present application, during the hydrothermal reaction, calcium disodium ethylenediaminetetraacetate and potassium dihydrogen phosphate react to form hydroxyapatite, which is compounded with nano-zinc oxide to form a nano-zinc oxide / hydroxyapatite composite coating.

[0073] In the present application, the zinc coating is not only a Zn source for the subsequent nano-zinc oxide coating, but also a transition layer between the zinc oxide / hydroxyapatite composite coating and the substrate, which can alleviate the mismatch between the mechanical properties of the substrate and the composite coating, and avoid cracking or peeling of the composite coating on the surface of the metal substrate.

[0074] The method for hydrothermally generating a nano-zinc oxide / hydroxyapatite composite coating from a cold-sprayed zinc coating will be described in detail below with reference to the examples, but they should not be construed as limiting the scope of the present application.

[0075] Example 1

[0076] (1) Zinc powder was used as a cold-spraying raw material to cold-spray a zinc coating on the surface of an AZ91D magnesium alloy substrate, and the thickness of the zinc coating was about 1000μm.

[0077] (2) A sodium hydroxide solution was used as a hydrothermal solution to perform a hydrothermal reaction on the surface of the cold-sprayed zinc coating, and a nano-zinc oxide coating was obtained; the hydrothermal reaction temperature was 150°C; the hydrothermal reaction time was 24h; and the concentration of the sodium hydroxide solution was 1mol / L.

[0078] (3) A mixed solution of calcium disodium ethylenediaminetetraacetate and potassium dihydrogen phosphate was used as a hydrothermal solution to perform a second-step hydrothermal reaction on the basis of the first-step hydrothermal reaction, and a nano-hydroxyapatite coating was obtained;

[0079] The hydrothermal reaction solution was a mixed solution of 0.25mol / L calcium disodium ethylenediaminetetraacetate and 0.15mol / L potassium dihydrogen phosphate, and a sodium hydroxide solution was added to adjust the pH of the solution to 11; the hydrothermal reaction temperature was 110°C; and the hydrothermal reaction time was 16h.

[0080] Figure 1The surface morphology of the nano zinc oxide / hydroxyapatite composite coating obtained in Example 1 (left) and the surface morphology of the coating after immersion in Hanks' simulated body fluid for 14 days (right) are shown. As can be seen from the left-hand figure, the coating presents a "flower ball-like" structure, which is composed of fine needle-like or rod-like crystals in a cluster structure. As can be seen from the right-hand figure, after immersion, the coating surface is composed of spherical particles, which are relatively uniform in size and appear in a cluster form, forming a "bouquet" or "coral" structure. Note: Hanks' simulated body fluid is a general-purpose solution, and its composition is: 142.0 mM Na + , 5.0 mM K + , 1.5 mM Mg 2+ , 2.5 mM Ca 2+ , 103.0 mM Cl - , 10.0 mM HCO3 - , 1.0 mM HPO4 2- , 0.5 mM SO4 2- , which can simulate the mineralization ability of the coating in human body fluids.

[0081] Figure 2 The morphology (left) and energy spectrum (right) of the nano zinc oxide / hydroxyapatite composite coating after immersion obtained in Example 1 are shown. The calcium / phosphorus ratio of the coating surface and cross-section is 1.63 and 1.65, respectively, which is comparable to the calcium / phosphorus ratio of hydroxyapatite, i.e. 1.66, indicating that the synthesized hydroxyapatite has a high purity.

[0082] Figure 3 The cross-sectional morphology (left) and energy spectrum (right) of the nano zinc oxide / hydroxyapatite composite coating are shown. It can be seen that the nano zinc oxide / hydroxyapatite composite coating is generated on the surface of the cold sprayed zinc coating, and the coating and the substrate have a clear interface and are tightly bonded to the substrate, without obvious peeling or delamination.

[0083] The cold sprayed zinc coating substrate (referred to as Mg-Zn) in step (1) of Example 1, the coating obtained in step (2) (referred to as Mg-Zn / ZnO), the composite coating obtained in step (3) (referred to as Mg-Zn / ZnO / HA), and the composite coating after immersion (referred to as immersed Mg-Zn / ZnO / HA) were subjected to XRD characterization, and the results are shown in Figure 4 . From Figure 4The XRD pattern of the cold sprayed zinc coating substrate can be seen that the zinc oxide / hydroxyapatite composite coating is formed by two-step hydrothermal method, the needle-like or rod-like crystals are zinc oxide / hydroxyapatite composite nanocrystals, and form dense cluster structure. After soaking in Hanks' simulated body fluid for 14 days, more crystals appear on the surface of the coating, and the intensity of the diffraction peak decreases obviously, which is due to the mineralization reaction of the coating in the simulated body fluid, and the formation of amorphous calcium phosphate layer. The above results show that the cold sprayed zinc surface nano zinc oxide / hydroxyapatite composite coating has high biological activity, which is specifically manifested in that the coating generates amorphous calcium phosphate after soaking, and the calcium phosphate has good biological activity.

[0084] Example 2

[0085] (1) Zinc powder is used as a cold spraying raw material to cold spray a zinc coating on the surface of an AZ91D magnesium alloy substrate, and the thickness of the zinc coating is about 1000 μm.

[0086] (2) A sodium hydroxide solution is used as a hydrothermal solution to perform a hydrothermal reaction on the surface of the cold sprayed zinc coating substrate to form a nano zinc oxide coating. The hydrothermal reaction temperature is 130°C, the hydrothermal reaction time is 16 h, and the concentration of the sodium hydroxide solution is 1 mol / L.

[0087] (3) A mixed solution of calcium disodium ethylenediaminetetraacetate and potassium dihydrogen phosphate is used as a hydrothermal solution to perform a second-step hydrothermal reaction on the basis of the first-step hydrothermal reaction to generate nano hydroxyapatite, and a nano zinc oxide / hydroxyapatite composite coating is obtained.

[0088] The hydrothermal reaction solution is a mixed solution of 0.25 mol / L calcium disodium ethylenediaminetetraacetate and 0.15 mol / L potassium dihydrogen phosphate, and a sodium hydroxide solution is added later to adjust the pH of the solution to 8.5. The hydrothermal reaction temperature is 110°C, and the hydrothermal reaction time is 8 h.

[0089] Figure 5 The surface morphology of the nano zinc oxide / hydroxyapatite composite coating obtained in Example 2 (left) and the surface morphology of the coating after soaking in Hanks' simulated body fluid for 14 days (right) are shown. As can be seen from the left figure, the coating presents a "coral-like" or "dendritic" structure. As can be seen from the right figure, the surface of the coating after soaking is composed of needle-like crystals, which exist in a clustered form to form a "flower" or "star" structure.

[0090] Figure 6 and Figure 7 The surface morphology and cross-sectional morphology and energy spectrum after soaking in Hanks' simulated body fluid for 14 days are shown. The surface energy spectrum of the coating shows that the calcium and phosphorus elements are less, while the cross-sectional EDS shows that the calcium and phosphorus elements are more, which may be due to the dissolution of hydroxyapatite and zinc oxide in the soaking process, releasing Ca2+ and PO4 3- ions into the solution. Figure 7 It can be seen from the micrographs that the coating and the substrate have obvious interface, and are tightly combined without obvious peeling or separation.

[0091] The cold-sprayed zinc coating substrate (abbreviated as Mg-Zn) in step (1) of Example 2, the coating obtained in step (2) (abbreviated as Mg-Zn / ZnO), the composite coating obtained in step (3) (abbreviated as Mg-Zn / ZnO / HA), and the composite coating after immersion (abbreviated as immersed Mg-Zn / ZnO / HA) were characterized by XRD, and the results are shown in Figure 8 From the XRD patterns of the composite coating before and after immersion, it can be seen that the cold-sprayed zinc coating substrate is converted into a zinc oxide / hydroxyapatite composite coating by the two-step hydrothermal method, and grows outward at a certain angle to form a complex structure similar to coral or dendrite. Figure 8 After immersion, the diffraction peak intensity of hydroxyapatite and other diffraction peaks decreases, and amorphous calcium phosphate is generated after immersion.

[0092] The above results show that the nano zinc oxide / hydroxyapatite composite coating on the surface of the cold-sprayed zinc has high biological activity.

[0093] Example 3

[0094] (1) Zinc powder was used as a cold-spraying raw material to cold-spray a zinc coating on the surface of an AZ91D magnesium alloy substrate, and the thickness of the zinc coating was about 1000 μm.

[0095] (2) A sodium hydroxide solution was used as a hydrothermal solution to perform a hydrothermal reaction on the surface of the cold-sprayed zinc coating substrate, and a nano zinc oxide coating was obtained. The hydrothermal reaction temperature was 150°C, the hydrothermal reaction time was 8h, and the concentration of the sodium hydroxide solution was 1 mol / L.

[0096] (3) A mixed solution of calcium disodium ethylenediaminetetraacetate and potassium dihydrogen phosphate was used as a hydrothermal solution to perform a second-step hydrothermal reaction on the basis of the first-step hydrothermal reaction, and nano hydroxyapatite was generated to obtain a nano zinc oxide / hydroxyapatite composite coating.

[0097] The hydrothermal reaction solution was a mixed solution of 0.25 mol / L calcium disodium ethylenediaminetetraacetate and 0.15 mol / L potassium dihydrogen phosphate, and a sodium hydroxide solution was added to adjust the pH of the solution to 8.5. The hydrothermal reaction temperature was 110°C, and the hydrothermal reaction time was 16h.

[0098] Figure 9 The surface morphology of the nano zinc oxide / hydroxyapatite composite coating obtained in Example 3 (left) and the surface morphology of the composite coating after immersion in Hanks' simulated body fluid for 14 days (right). From the surface morphology of the composite coating before and after immersion, it can be seen that the zinc oxide / hydroxyapatite composite coating has a complex structure similar to coral or dendrite, and the surface of the composite coating after immersion is relatively smooth. Figure 9It can be seen that the coating surface is dense before soaking, the zinc oxide particles are uniformly dispersed in the hydroxyapatite matrix, and there is no obvious crack. After soaking, the coating surface is composed of star-shaped crystals, which exist in the form of clusters, forming a structure similar to "snowflakes" or "star flowers", and there is no obvious crack.

[0099] Figure 10 and Figure 11 The surface and cross-sectional morphologies and energy spectrum after soaking in Hanks' simulated body fluid for 14 days are shown. The coating changes from an elongated sharp dendritic structure to a thick and dense bouquet structure, indicating that a significant mineralization process occurs on the coating surface during soaking, and amorphous calcium phosphate may be generated. The calcium to phosphorus ratio of the surface and cross-section after soaking is 1.92 and 1.42, respectively, which is comparable to the calcium to phosphorus ratio of hydroxyapatite 1.66, indicating that the synthesized hydroxyapatite has high purity. The coating has an obvious interface with the substrate and is tightly bonded to the substrate without obvious peeling or peeling phenomenon.

[0100] The cold sprayed zinc coating substrate (referred to as Mg-Zn) in step (1) of Example 3, the coating obtained in step (2) (referred to as Mg-Zn / ZnO), the composite coating obtained in step (3) (referred to as Mg-Zn / ZnO / HA), and the composite coating after soaking (referred to as soaked Mg-Zn / ZnO / HA) were subjected to XRD characterization, and the results are shown in Figure 12 From Figure 12 It can be seen that there are obvious zinc oxide and hydroxyapatite phases before soaking, and the intensity of the zinc oxide and hydroxyapatite peaks decreases after soaking, indicating that the hydroxyapatite and zinc oxide nanocrystals have degraded to form amorphous calcium phosphate.

[0101] Example 4

[0102] (1) Zinc powder was used as a cold spraying raw material to cold spray a zinc coating on the surface of an AZ91D magnesium alloy substrate, and the thickness of the zinc coating was about 1000 μm.

[0103] (2) A sodium hydroxide solution was used as a hydrothermal solution to perform a hydrothermal reaction on the surface of the cold sprayed zinc coating substrate, and a nano-zinc oxide coating was obtained. The hydrothermal reaction temperature was 150°C, the hydrothermal reaction time was 24h, and the concentration of the sodium hydroxide solution was 2mol / L.

[0104] (3) A mixture of calcium disodium ethylenediaminetetraacetate and potassium dihydrogen phosphate solution was used as a hydrothermal solution to perform a second step hydrothermal reaction on the basis of the first step hydrothermal reaction, to generate nano-hydroxyapatite, and obtain a nano-zinc oxide / hydroxyapatite composite coating;

[0105] The hydrothermal reaction solution was a mixed solution of 0.25 mol / L calcium disodium ethylenediaminetetraacetate and 0.15 mol / L potassium dihydrogen phosphate, followed by the addition of sodium hydroxide solution to adjust the pH of the solution to 10; the hydrothermal reaction temperature was 130℃; and the hydrothermal reaction time was 16 h.

[0106] Figure 13 The image shows the surface morphology of the nano-zinc oxide / hydroxyapatite composite coating obtained in Example 4 (left) and its surface morphology after immersion in Hanks' simulated body fluid for 14 days (right). Before immersion, the coating surface is dense, with zinc oxide particles uniformly dispersed in the hydroxyapatite matrix and no obvious cracks. After immersion, the coating surface is composed of fibrous crystals, which exist in clusters, forming a structure similar to "coral" or "velvet". At the same time, there are no obvious cracks on the coating surface.

[0107] Figure 14 and Figure 15 The images show the surface morphology (left) and energy dispersive spectroscopy (EDS) and cross-sectional morphology (left) and EDS (right) after immersion in Hanks' simulated body fluid for 14 days. Figure 14 and 15 Energy dispersive spectroscopy (EDS) showed that hydroxyapatite and zinc oxide nanocrystals degraded, forming amorphous calcium phosphate. The calcium-to-phosphorus ratios on the surface and cross-section after soaking were 1.44 and 1.41, respectively, comparable to the hydroxyapatite ratio of 1.66, indicating that the synthesized hydroxyapatite had high purity. Meanwhile... Figure 15 It can be seen that there is a clear interface between the coating and the substrate, and the coating is tightly bonded to the substrate without any obvious peeling or detachment.

[0108] XRD characterization was performed on the cold-sprayed zinc coating substrate (Mg-Zn) in step (1) of Example 4, the coating obtained in step (2) (Mg-Zn / ZnO), the composite coating obtained in step (3) (Mg-Zn / ZnO / HA), and the composite coating after immersion (immersion Mg-Zn / ZnO / HA). The results are shown in the figure. Figure 16 .from Figure 16 It can be seen that there are obvious zinc oxide and hydroxyapatite phases before soaking. After soaking, the intensity of zinc oxide and hydroxyapatite peaks decreases, and amorphous calcium phosphate is formed.

[0109] Example 5

[0110] (1) Zinc powder is used as a cold spraying material, and the zinc coating is prepared by cold spraying;

[0111] (2) A nano-zinc oxide coating was obtained by hydrothermal reaction on the surface of a cold-sprayed zinc coating substrate using sodium hydroxide solution as the hydrothermal solution. The hydrothermal reaction temperature was 130℃; the hydrothermal reaction time was 24h; and the concentration of sodium hydroxide solution was 2mol / L.

[0112] (3) Using a mixed solution of calcium disodium ethylenediaminetetraacetate and potassium dihydrogen phosphate as a hydrothermal solution, a second hydrothermal reaction is carried out on the basis of the first hydrothermal reaction to generate nano-hydroxyapatite and obtain a nano-zinc oxide / hydroxyapatite composite coating.

[0113] The hydrothermal reaction solution was a mixed solution of 0.25 mol / L calcium disodium ethylenediaminetetraacetate and 0.15 mol / L potassium dihydrogen phosphate, followed by the addition of sodium hydroxide solution to adjust the pH of the solution to 11; the hydrothermal reaction temperature was 110℃; and the hydrothermal reaction time was 24 h.

[0114] Figure 17 The images show the surface morphology of the nano-zinc oxide / hydroxyapatite composite coating obtained in Example 5 (left) and its surface morphology after immersion in Hanks' simulated body fluid for 14 days (right). Before immersion, the coating surface is dense, with zinc oxide particles uniformly dispersed in the hydroxyapatite matrix and no obvious cracks. After immersion, the coating surface consists of spherical particles that are tightly aggregated together, forming a structure similar to "raspberries" or "grape bunches." The spherical particles appear relatively smooth, are relatively uniform in size, and have no obvious cracks.

[0115] Figure 18 The image shows the surface morphology (left) and energy dispersive spectroscopy (right) after immersion in Hanks' simulated body fluid for 14 days. Figure 19 The cross-sectional morphology (left) and energy dispersive spectroscopy (right) of the sample after immersion in Hanks' simulated body fluid for 14 days are shown. Figure 18 and 19 Energy dispersive spectroscopy (EDS) showed that hydroxyapatite and zinc oxide nanocrystals degraded to form amorphous calcium phosphate. The calcium-to-phosphorus ratios on the surface and cross-section after soaking were 1.41 and 1.56, respectively, which are comparable to the calcium-to-phosphorus ratio of hydroxyapatite (1.66), indicating that the synthesized hydroxyapatite has high purity. Figure 19 The coating shows a clear interface with the substrate, is tightly bonded to the substrate, and shows no obvious peeling or detachment.

[0116] XRD characterization was performed on the cold-sprayed zinc coating substrate (Mg-Zn) in step (1) of Example 5, the coating obtained in step (2) (Mg-Zn / ZnO), the composite coating obtained in step (3) (Mg-Zn / ZnO / HA), and the composite coating after immersion (immersion Mg-Zn / ZnO / HA). The results are shown in the figure. Figure 20 .from Figure 20 It can be seen that there are obvious zinc oxide and hydroxyapatite phases before soaking. After soaking, the intensity of zinc oxide and hydroxyapatite peaks decreases, and amorphous calcium phosphate is formed.

[0117] Comparative Example 1

[0118] The sample is an AZ91D magnesium alloy matrix.

[0119] Figure 21 The image shows the surface morphology of the AZ91D magnesium alloy in Comparative Example 1 (left) and its surface morphology after immersion in Hanks' simulated body fluid for 14 days (right). Before immersion, the coating surface showed a smooth metallic surface; after immersion, white granular products appeared on the surface, indicating that the AZ91D magnesium alloy was corroded in the body fluid to form white corrosion products.

[0120] Figure 22 and Figure 23 The images show the surface and cross-sectional morphology and energy spectrum of the sample after immersion in Hanks' simulated body fluid for 14 days. The intensity of the Mg peak decreased after immersion, indicating the formation of a new phase, which is an amorphous corrosion product.

[0121] Figure 24 The image shows the XRD pattern of AZ91D magnesium alloy. After immersion, the intensity of the Mg peak decreased, indicating the formation of amorphous corrosion products.

[0122] Comparative Example 2

[0123] Zinc powder was used as a cold spraying material to cold spray a zinc coating onto the surface of an AZ91D magnesium alloy substrate. The zinc coating thickness was approximately 1000 μm.

[0124] Figure 25 The image shows the surface morphology of the zinc coating obtained in Comparative Example 2 (left) and its surface morphology after immersion in Hanks' simulated body fluid for 14 days. Before immersion, the coating surface exhibits an uneven granular structure; after immersion, a layer of white product appears on the surface, indicating that the zinc coating has undergone corrosion in the body fluid.

[0125] Figure 26 and Figure 27 The images show the surface and cross-sectional morphology and energy dispersive spectroscopy of the sample after immersion in Hanks' simulated body fluid for 14 days. The zinc peak intensity decreased after immersion, indicating the formation of a new phase, which may be an amorphous corrosion product.

[0126] Figure 28 The images show the phase structure of the zinc coating before and after immersion. The intensity of the zinc diffraction peaks decreased after immersion.

[0127] Comparative Example 3

[0128] (1) Zinc powder is used as a cold spraying material to cold spray a zinc coating on the surface of AZ91D magnesium alloy substrate. The zinc coating thickness is about 1000μm.

[0129] (2) A nano-zinc oxide coating was obtained by hydrothermal reaction on the surface of a cold-sprayed zinc coating substrate using sodium hydroxide solution as the hydrothermal solution. The hydrothermal reaction temperature was 130℃; the hydrothermal reaction time was 16h; and the concentration of sodium hydroxide solution was 1.5mol / L.

[0130] Figure 29 The image shows the surface morphology of the nano-zinc oxide coating obtained in Comparative Example 3 (left) and its surface morphology after immersion in Hanks' simulated body fluid for 14 days (right). Before immersion, the coating surface exhibits a uniformly distributed nanoparticle structure; after immersion, honeycomb-like pores appear on the surface, indicating that zinc oxide undergoes non-uniform dissolution in the body fluid.

[0131] Figure 30 and Figure 31 The images show the surface and cross-sectional morphology and energy dispersive spectroscopy of the zinc oxide after immersion in Hanks' simulated body fluid for 14 days. The zinc oxide peak intensity decreased after immersion, indicating the formation of a new phase, which may be an amorphous corrosion product.

[0132] XRD characterization was performed on the cold-sprayed zinc coating substrate (Mg-Zn) in step (1) of Comparative Example 3, the nano-zinc oxide coating (Mg-Zn / ZnO) obtained in step (2), and the immersed nano-zinc oxide coating (immersed Mg-Zn / ZnO). The results are shown in the figure. Figure 32 .Depend on Figure 32 It can be seen that there are obvious zinc oxide diffraction peaks before soaking, and the intensity of zinc oxide diffraction peaks decreases after soaking.

[0133] Comparative Example 4

[0134] (1) Zinc powder is used as a cold spraying material to cold spray a zinc coating on the surface of AZ91D magnesium alloy substrate. The zinc coating thickness is about 1000μm.

[0135] (2) Using a mixed solution of calcium disodium ethylenediaminetetraacetate and potassium dihydrogen phosphate as a hydrothermal solution, a hydrothermal reaction was carried out to generate nano-hydroxyapatite, and a zinc / hydroxyapatite composite coating was obtained.

[0136] The hydrothermal reaction solution was a mixture of 0.25 mol / L calcium disodium ethylenediaminetetraacetate and 0.15 mol / L potassium dihydrogen phosphate, followed by the addition of sodium hydroxide solution to adjust the pH of the solution to 11; the hydrothermal reaction temperature was 120℃; and the hydrothermal reaction time was 16 h.

[0137] Figure 33 The images show the surface morphology of the composite coating obtained in Comparative Example 4 (left) and its surface morphology after immersion in Hanks' simulated body fluid for 14 days (right). Figure 33 It can be seen that the white product on the coating surface dissolves after soaking.

[0138] Figure 34 The surface morphology (left) and energy dispersive spectroscopy (right) of the sample after immersion in Hanks' simulated body fluid for 14 days are shown. Figure 35The cross-sectional morphology (left) and energy spectrum (right) after soaking in Hanks' simulated body fluid for 14 days. The energy spectrum shows that the calcium and phosphorus contents of the surface cross-section are low. The calcium / phosphorus ratio of the coating surface and cross-section is 0.47 and 1.31, respectively, which is lower than the calcium / phosphorus ratio of hydroxyapatite (1.66). The coating and the substrate have an obvious interface and are tightly combined, without obvious peeling or separation.

[0139] The cold-sprayed zinc coating substrate (Mg-Zn) in step (1) of Comparative Example 4, the zinc / hydroxyapatite composite coating (Mg-Zn / HA) obtained in step (2), and the zinc / hydroxyapatite composite coating after soaking (soaked Mg-Zn / HA) were subjected to XRD characterization, and the results are shown in Table 1. Figure 36 As shown in Table 1, the diffraction peak of hydroxyapatite in the coating after soaking is reduced, indicating that the hydroxyapatite is degraded to form amorphous calcium phosphate. Figure 36

[0140] As can be seen from the above examples and comparative examples, the nano zinc oxide / hydroxyapatite composite coating prepared by the method of the present application has good biological properties.

[0141] The above description is only preferred embodiments of the present application, and it should be pointed out that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.​

Claims

1. A method of hydrothermally generating a nano-zinc oxide / hydroxyapatite composite coating from a cold sprayed zinc coating, comprising the steps of: The zinc powder is cold sprayed on the surface of a metal matrix to form a zinc coating, thereby obtaining a first intermediate body; The first intermediate body is placed above the liquid level of a sodium hydroxide solution to perform a first hydrothermal reaction, thereby forming a nano-zinc oxide coating and obtaining a second intermediate body; The second intermediate body is placed in a mixed solution of calcium disodium ethylenediaminetetraacetate and potassium dihydrogen phosphate to perform a second hydrothermal reaction, thereby generating nano-hydroxyapatite and obtaining a nano-zinc oxide / hydroxyapatite composite coating; the pH value of the mixed solution of calcium disodium ethylenediaminetetraacetate and potassium dihydrogen phosphate is 7-13.

2. The method of claim 1, wherein, The thickness of the zinc coating is greater than 10 microns.

3. The method of claim 1, wherein, The concentration of the sodium hydroxide solution is 0.5-3 mol / L.

4. The method according to claim 1 or 3, characterized in that, The temperature of the first hydrothermal reaction is 80-170 DEG C.

5. The method of claim 4, wherein, The time of the first hydrothermal reaction is 6-36 hours.

6. The method of claim 1, wherein, The molar ratio of calcium disodium ethylenediaminetetraacetate to potassium dihydrogen phosphate is 1.66-1.67:

1.

7. The method of claim 6, wherein, In the mixed solution of calcium disodium ethylenediaminetetraacetate and potassium dihydrogen phosphate, the concentration of calcium disodium ethylenediaminetetraacetate is 0.05-0.60 mol / L.

8. The method of claim 1, 6 or 7, wherein, The temperature of the second hydrothermal reaction is 70-180 DEG C.

9. The method of claim 8, wherein, The time of the second hydrothermal reaction is 6-36 hours.

10. The method of claim 1, wherein, The metal matrix comprises AZ91D magnesium alloy.

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