阅读说明：本技术 一种金属表面沉积羟基磷灰石的方法及金属植入物 (Method for depositing hydroxyapatite on metal surface and metal implant ) 是由 姚夏睿 俞天白 于 2019-11-11 设计创作，主要内容包括：本发明涉及金属表面沉积羟基磷灰石的方法及金属植入物,所述金属表面沉积羟基磷灰石的方法,其包括：提供金属基材；在所述金属基材的表面形成粗糙结构；提供电解液；以及,将表面形成有粗糙结构的金属基材置于所述电解液中,经电化学沉积在所述粗糙结构上形成羟基磷灰石层；其中,用于配制所述电解液的原料包括钙盐、磷酸盐及过氧化氢。通过本发明得到的金属植入物表面形成有高纯度和结晶度的HA涂层,且HA涂层与金属植入物的表面具有较强的结合力,从而改善金属植入物的使用安全性和可靠性。(The invention relates to a method for depositing hydroxyapatite on a metal surface and a metal implant, wherein the method for depositing hydroxyapatite on the metal surface comprises the following steps: providing a metal substrate; forming a rough structure on the surface of the metal substrate; providing an electrolyte; placing the metal substrate with the rough structure formed on the surface in the electrolyte, and forming a hydroxyapatite layer on the rough structure through electrochemical deposition; wherein, the raw materials for preparing the electrolyte comprise calcium salt, phosphate and hydrogen peroxide. The HA coating with high purity and crystallinity is formed on the surface of the metal implant obtained by the invention, and the HA coating and the surface of the metal implant have stronger bonding force, thereby improving the use safety and reliability of the metal implant.)

1. A method for depositing hydroxyapatite on a metal surface is characterized by comprising the following steps:

providing a metal substrate;

forming a rough structure on the surface of the metal substrate;

providing an electrolyte; and the number of the first and second groups,

placing the metal substrate with the rough structure formed on the surface in the electrolyte, and forming a hydroxyapatite layer on the rough structure through electrochemical deposition; wherein, the raw materials for preparing the electrolyte comprise calcium salt, phosphate and hydrogen peroxide.

2. The method for depositing hydroxyapatite on a metal surface according to claim 1, characterized in that the method for forming the rough structure on the surface of the metal substrate comprises at least one of the following methods:

the method a comprises the following steps: putting the metal base material into the mixed acid solution, and carrying out water bath reaction for 1-2 h at the temperature of 60-70 ℃; taking out the metal base material, cleaning and drying;

the method b: putting the metal base material into an alkaline solution, and carrying out water bath reaction for 6-12 h at the temperature of 55-65 ℃; taking out the metal base material, cleaning and drying;

the method c comprises the following steps: in the fluorine-containing acid solution, the metal substrate is used as an anode, the inert electrode is used as a cathode, and direct current of 30-60V is applied between the electrodes for reaction for 15-60 min; and taking out the metal base material, cleaning and drying.

3. The method for depositing hydroxyapatite on the metal surface according to claim 2, wherein in the method a, the mixed acid solution is formed by mixing sulfuric acid and hydrochloric acid, and the concentration of the sulfuric acid is 20% to 30% and the concentration of the hydrochloric acid is 5% to 15% by mass percentage.

4. The method for depositing hydroxyapatite on the metal surface according to claim 2, wherein in the method b, the alkaline solution is an aqueous solution of hydroxide of alkali metal, and the concentration of the alkaline solution is 5mol/L-10 mol/L.

5. The method for depositing hydroxyapatite on the metal surface according to claim 2, wherein in the method c, the concentration of the oxyacid in the fluorine-containing acid solution is 0.1mol/L-1mol/L, and the concentration of the fluoride ion is 0.15mol/L-0.3 mol/L.

6. The method for depositing hydroxyapatite on a metal surface according to any one of claims 2 to 5, characterized in that the method for forming a rough structure on the surface of the metal substrate comprises:

firstly, carrying out the method a, and then carrying out the method b; or

Method a is performed first, followed by method c.

7. The method for depositing hydroxyapatite on a metal surface according to claim 1, characterized in that the electrolyte has a conductivity comprised between 1500 and 2000 μ S/cm, a pH comprised between 5 and 6.5, and a calcium to phosphorus ratio comprised between 1.6 and 1.7:1, the hydrogen peroxide concentration being comprised between 6% and 12% in percentage by volume.

8. The method for depositing hydroxyapatite on a metal surface according to claim 1, characterized in that the raw material for preparing the electrolyte further comprises an ionic compound selected from at least one of ammonium chloride, sodium chloride and potassium chloride.

9. The method for depositing hydroxyapatite on the metal surface according to claim 1, wherein the electrolyte is prepared by using at least one phosphate selected from ammonium hydrogen phosphate and ammonium dihydrogen phosphate, and the electrolyte is prepared by using at least one calcium salt selected from calcium acetate and calcium nitrate.

10. The method for depositing hydroxyapatite on a metal surface according to claim 1, characterized in that the electrochemical deposition method comprises: and intermittently introducing direct current with constant current between the metal substrate with the rough structure formed on the surface as a cathode and the inert electrode as an anode at the temperature of between 25 and 70 ℃ to perform reaction.

11. The method for depositing hydroxyapatite on a metal surface according to claim 10, characterized in that the current density of the direct current is 20mA/cm²-50mA/cm²The time length of each time of electrifying is 10s-300s, the time length of each time of deenergizing is 10s-300s, the electrifying times are 2-90 times, the times of deenergizing are the same as the times of electrifying, and the total time length of electrifying in the whole reaction process is 180s-900 s.

12. The method for depositing hydroxyapatite on a metal surface according to claim 1, characterized in that the metal substrate further comprises a post-treatment after the electrochemical deposition; the post-processing method comprises the following steps: cleaning the metal substrate subjected to electrochemical deposition by using water; then, the metal base material is placed in an alkaline solution to be soaked for 1-2 h; and finally, taking out the metal base material, cleaning and drying.

13. The method for depositing hydroxyapatite on the metal surface according to claim 1, characterized in that before the forming of the rough structure on the surface of the metal substrate, the method further comprises: cleaning the metal substrate, the method of cleaning the metal substrate comprising: washing with water, washing with alcohol, washing with water, pickling and washing with water in sequence; wherein the pickling detergent is prepared by mixing 20-40% by mass of nitric acid and 3-5% by mass of hydrofluoric acid.

14. A metal implant comprising a body having a surface deposited with hydroxyapatite using a method according to any one of claims 1 to 13.

Technical Field

The invention relates to the technical field of medical instruments, in particular to a method for depositing hydroxyapatite on a metal surface and a metal implant.

Background

Metal materials have wide applications in the field of medical implants due to their excellent properties. Common metal materials such as stainless steel, titanium and titanium alloy, zirconium and zirconium alloy, cobalt-chromium alloy, etc. are the preferred materials for implanting and replacing hard tissues in orthopaedics, dentistry, etc. due to good biocompatibility, low toxicity, proper mechanical strength and sufficient corrosion resistance. However, most metallic materials tend to be biologically inert in the human body without special surface treatments. This makes it difficult for the metal implant to form an effective osseointegration interface with the surrounding bone tissue in the human body, which leads to problems such as loosening of the metal implant, fibrosis of the surrounding tissue, and chronic inflammation.

Hydroxyapatite (HA, molecular formula Ca)₁₀(PO₄)₆(OH)₂) The HA-HA mineral is one of main mineral components in animals and human bodies, and the HA content in human enamel reaches 96% wt, and the HA content in bone reaches 69% wt. In human body, HA is in the form of acicular nanoparticles, with a length of 20-40nm and a width of 2-4 nm. A large number of researches show that the HA particles formed on the surface of the metal implant can improve the biocompatibility and the bioactivity of the metal implant, and the HA particles are used as an induction factor in the bone formation process, so that the osseointegration process of the metal implant is facilitated.

Currently, there are many metal implants with HA coatings formed on the surfaces, and these metal implants form HA coatings on metal substrates by means of plasma spraying, electrochemical deposition, and the like. However, the HA coating formed by the existing method still HAs some problems, resulting in poor performance of the metal implant. For example, the coating thickness of HA formed by plasma spraying method, in which HA powder is sprayed onto a metal implant by high temperature and high speed plasma jet, is several tens or even hundreds of micrometers. During the spraying process, HA powder is very easy to melt and degrade, so that more soluble amorphous HA and calcium phosphate exist in the coating. After the metal implant is implanted into the human body, these soluble HA and calcium phosphate are degraded, causing voids and peeling of the coating, which in turn leads to cracking and peeling of the coating. In this case, a larger coating thickness means that there is a larger gap and more HA fragments between the metal implant and the bone tissue, resulting in a long-term loosening and inflammation in the implant. Meanwhile, for metal plants with three-dimensional structures such as gaps formed on the surface, the plasma spraying is linear spraying, HA cannot enter the three-dimensional structures, and the phenomenon of blocking the gaps even occurs in an excessively thick coating. When the HA coating is formed on the surface of the metal implant by using an electrochemical deposition method, the problems of poor surface binding force between the coating and the metal implant, low HA particle crystallinity and high soluble calcium phosphate content exist.

Disclosure of Invention

The invention aims to provide a method for depositing hydroxyapatite on a metal surface and a metal implant.

In order to achieve the above object, the present invention provides a method for depositing hydroxyapatite on a metal surface, comprising:

providing a metal substrate;

forming a rough structure on the surface of the metal substrate;

providing an electrolyte; and the number of the first and second groups,

placing a metal substrate with a rough structure formed on the surface in the electrolyte, and forming a hydroxyapatite layer on the rough structure through electrochemical deposition; wherein, the raw materials for preparing the electrolyte comprise calcium salt, phosphate and hydrogen peroxide.

Alternatively, the method of forming the roughness structure on the surface of the metal substrate includes at least one of the following methods:

the method a comprises the following steps: putting the metal base material into the mixed acid solution, and carrying out water bath reaction for 1-2 h at the temperature of 60-70 ℃; taking out the metal base material, cleaning and drying;

the method b: putting the metal base material into an alkaline solution, and carrying out water bath reaction for 6-12 h at the temperature of 55-65 ℃; taking out the metal base material, cleaning and drying;

the method c comprises the following steps: in the fluorine-containing acid solution, the metal substrate is used as an anode, the inert electrode is used as a cathode, and direct current of 30-60V is applied between the electrodes for reaction for 15-60 min; and taking out the metal base material, cleaning and drying.

Optionally, in the method a, the mixed acid solution is prepared by mixing sulfuric acid and hydrochloric acid, and the concentration of the sulfuric acid is 20% to 30% and the concentration of the hydrochloric acid is 5% to 15% by mass percent.

Alternatively, in the method b, the alkaline solution is an aqueous solution of an alkali metal hydroxide, and the concentration of the alkaline solution is 5mol/L to 10 mol/L.

Optionally, in the method c, in the fluorine-containing acid solution, the concentration of the oxyacid is 0.1mol/L-1mol/L, and the concentration of the fluoride ion is 0.15mol/L-0.3 mol/L.

Alternatively, the method of forming a roughness structure on the surface of a metal substrate comprises:

firstly, carrying out the method a, and then carrying out the method b; or

Method a is performed first, followed by method c.

Optionally, the electrolyte has a conductivity between 1500 μ S/cm and 2000 μ S/cm, a pH between 5 and 6.5, and a calcium to phosphorus ratio in the electrolyte of 1.6 to 1.7:1, with a hydrogen peroxide concentration of 6% to 12% by volume percent.

Optionally, the raw material for preparing the electrolyte further comprises an ionic compound, and the ionic compound is selected from at least one of ammonium chloride, sodium chloride and potassium chloride.

Optionally, the phosphate used in preparing the electrolyte is selected from ammonium hydrogen phosphate and ammonium dihydrogen phosphate, and the calcium salt used in preparing the electrolyte is selected from calcium acetate and calcium nitrate.

Optionally, the method of electrochemical deposition comprises: and intermittently introducing direct current with constant current between the metal substrate with the rough structure formed on the surface as a cathode and the inert electrode as an anode at the temperature of between 25 and 70 ℃ to perform reaction.

Optionally, the direct current has a current density of 20mA/cm²-50mA/cm²The time length of each power-on is 10s-300s, the time length of each power-off is 10s-300s, the power-on frequency is 2-90 times, the power-off frequency is the same as the power-on frequency, and the total power-on time in the whole reaction processThe length is 180s-900 s.

Optionally, after the electrochemical deposition, the metal substrate further comprises a post-treatment; the post-processing method comprises the following steps: cleaning the metal substrate subjected to electrochemical deposition by using water; then, the metal base material is placed in an alkaline solution to be soaked for 1-2 h; and finally, taking out the metal base material, cleaning and drying.

Optionally, before forming the rough structure on the surface of the metal substrate, the method further comprises: cleaning the metal substrate, the method of cleaning the metal substrate comprising: washing with water, washing with alcohol, washing with water, pickling and washing with water in sequence; wherein the pickling detergent is prepared by mixing 20-40% by mass of nitric acid and 3-5% by mass of hydrofluoric acid.

To achieve the above object, the present invention also provides a metal implant comprising a body, the surface of which is deposited with hydroxyapatite using the method as described above.

Compared with the prior art, the method for depositing the hydroxyapatite on the metal surface and the metal implant have the following advantages:

the first and the aforementioned method for depositing hydroxyapatite on a metal surface comprises: forming a rough structure on the surface of the metal base material; placing a metal substrate in an electrolyte, and forming a hydroxyapatite layer on the rough structure through electrochemical deposition; wherein, the raw materials for preparing the electrolyte comprise calcium salt, phosphate and hydrogen peroxide. The electrolyte contains hydrogen peroxide, and in the process of electrochemical deposition, the strong oxidizing property of peroxide is utilized to change the reaction on the surface of the metal base material, so that the peroxide on the surface of the metal base material is preferentially reduced, hydrogen generation on the surface of the metal base material is inhibited, pores and fragments in the HA coating are reduced, and the binding force between the coating and the surface of the metal base material is improved.

Secondly, ionic compounds such as ammonium chloride are added into the electrolyte solution to improve the conductivity of the electrolyte, and intermittent electrification is carried out by combining with current with high current density, so that the HA purity and the crystallinity are improved, and meanwhile, the generation of hydrogen is further inhibited. The coating thickness of HA can be controlled by regulating and controlling the single electrifying time and the total electrifying time so as to obtain the HA coating with proper thickness.

Drawings

Fig. 1 is a scanning electron micrograph of a surface of a metal substrate according to an embodiment of the present invention, in which a micro-scale nano-structure is formed on the surface of the metal substrate, the micrograph being at a magnification of 5000 times;

fig. 2 is a scanning electron micrograph of a surface of a metal substrate according to the present invention provided in example 1, illustrating that the surface of the metal substrate is formed with an HA coating layer, the photograph being at a magnification of 5 ten thousand;

FIG. 3 is a scanning electron micrograph of a surface of a metal substrate according to example 2 of the present invention, in which a micro-scale roughness structure and a nano-scale roughness structure are simultaneously formed on the surface of the metal substrate, the micrograph being at a magnification of 1 ten thousand times;

fig. 4 is a scanning electron micrograph of a surface of a metal substrate according to example 2 of the present invention, in which a micro-scale roughness structure and a nano-scale roughness structure are simultaneously formed on the surface of the metal substrate, the micrograph being 10 ten thousand times;

FIG. 5 is a scanning electron micrograph of a surface of a metal substrate according to the present invention provided in example 2, illustrating that the surface of the metal substrate HAs formed an HA coating, the micrograph being at a magnification of 10 ten thousand;

FIG. 6 is a scanning electron micrograph of a surface of a metal substrate according to example 3 of the present invention, in which a nano-scale roughness structure is formed on the surface of the metal substrate, the micrograph being magnified 10 ten thousand times;

fig. 7 is a scanning electron micrograph of a surface of a metal substrate according to the present invention provided in example 3, illustrating that the surface of the metal substrate is formed with an HA coating layer, the photograph being at a magnification of 10 ten thousand;

fig. 8 is a scanning electron micrograph of a surface of a metal substrate according to the present invention provided in example 4, illustrating that the surface of the metal substrate is formed with an HA coating layer, the photograph being magnified 100 times;

fig. 9 is a scanning electron micrograph of a surface of a metal substrate according to the present invention provided in example 4, illustrating that the surface of the metal substrate is formed with an HA coating layer, the photograph being at a magnification of 10 ten thousand;

FIG. 10a is a scanning electron micrograph of a surface of a metal substrate having an HA coating formed thereon at an electrochemical deposition temperature of 25 ℃ according to example 5 of the present invention, the micrograph being at a magnification of 5 ten thousand;

fig. 10b is a scanning electron micrograph of a surface of a metal substrate at an electrochemical deposition temperature of 40 ℃ illustrating the surface of the metal substrate having an HA coating formed thereon at a magnification of 5 ten thousand according to example 5 of the present invention.

Detailed Description

To make the objects, advantages and features of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings.

As used in this specification, the singular forms "a," "an," and "the" include plural referents unless the content clearly dictates otherwise. As used in this specification, the term "or" is generally employed in its sense including "and/or" unless the content clearly dictates otherwise.

The present embodiment is directed to a method for depositing hydroxyapatite on a metal surface and a metal implant prepared by the method. The method for depositing hydroxyapatite on the surface of the metal comprises the following steps:

providing a metal substrate;

forming a rough structure on the surface of the metal substrate;

providing an electrolyte; and the number of the first and second groups,

placing a metal substrate with a rough structure formed on the surface in the electrolyte, and forming a hydroxyapatite layer on the rough structure through electrochemical deposition; wherein, the raw materials for preparing the electrolyte comprise calcium salt, phosphate and hydrogen peroxide.

On one hand, the surface of the metal substrate is provided with a rough structure, so that the hydrophilicity and the bioactivity of the surface of the metal substrate can be enhanced, and the deposition of HA particles is facilitated. On the other hand, hydrogen peroxide is added into the electrolyte, so that the surface of the metal base material is subjected to a reduction reaction of peroxide preferentially by utilizing the strong oxidizing property of the peroxide to inhibit the hydrogen from being generated on the surface of the metal base material in the electrochemical deposition process, thereby reducing pores and fragments in the HA coating and further improving the binding force between the coating and the surface of the metal base material.

Generally, most metal substrates have various particles and grease remained on the surface, and an oxide layer formed on the surface of the metal substrate due to the metal substrate being placed in the air is not favorable for the deposition of the HA particles. Therefore, before the surface of the metal substrate is formed with the rough structure, cleaning the metal substrate may be further included.

Optionally, the cleaning method of the metal implant sequentially comprises water washing, alcohol washing, water washing, acid washing and water washing. Specifically, the metal base material is rinsed by using pure water, isopropyl alcohol and pure water as cleaning agents in sequence to remove particles and grease on the metal base material. During the rinsing process, ultrasonic vibration can be simultaneously carried out to improve the cleaning effect. And then, placing the metal substrate in mixed acid liquid consisting of nitric acid and hydrofluoric acid for acid cleaning to remove the oxide layer on the metal substrate. It should be noted that the time for pickling should be controlled. The concentration of the nitric acid is between 20 and 40 percent and the concentration of the hydrofluoric acid is between 3 and 5 percent in percentage by mass.

And then, forming the rough structure on the surface of the metal substrate.

Specifically, the surface of the metal substrate may be formed with only the micro-scale roughness structure, only the nano-scale roughness structure, or both the micro-scale roughness junction and the nano-scale roughness structure. The shape of the nano-scale roughness structure may be a grid or a tube depending on the forming method.

There are many options for the method for forming the roughness structure on the surface of the metal substrate, and this example is only described by way of example, but these methods should not limit the present invention.

Optionally, the following method is adopted to form the micron-scale rough structure on the surface of the metal substrate: preparing mixed acid liquid, wherein the mixed acid liquid is prepared by mixing sulfuric acid and hydrochloric acid, and the concentration of the sulfuric acid is between 20 and 30 percent and the concentration of the hydrochloric acid is between 5 and 15 percent in percentage by mass. Then placing the metal base material in the mixed acid solution, heating the metal base material to 60-70 ℃ in a water bath, and carrying out heat preservation reaction for 1-2 h. And then taking out the metal base material, washing the metal base material by pure water, and finally drying the metal base material in an oven. Here, the standard for completion of cleaning is defined as pH neutrality of water used for washing the metal substrate, and hereinafter, the standard for completion of cleaning is the same.

Optionally, a latticed nanoscale rough structure is formed on the surface of the metal substrate by adopting the following method: preparing an alkaline solution, wherein the alkaline solution is a strong alkaline concentrated solution. Preferably, the alkaline solution may be an aqueous solution of an alkali metal hydroxide, such as a sodium hydroxide solution, a potassium hydroxide solution, or the like, and the concentration of the alkaline solution may be between 5mol/L and 10 mol/L. Then placing the metal base material in the alkaline solution, heating the metal base material to 55-65 ℃ in a water bath, and carrying out heat preservation reaction for 6-12 h. And then taking out the metal base material, cleaning the metal base material by pure water, and finally drying.

Optionally, the tubular nano-scale rough structure is formed on the surface of the metal substrate by adopting the following method: preparing fluorine-containing acid solution, and applying direct current of 30-60V between electrodes for reaction for 15-60 min by taking the fluorine-containing acid solution as electrolyte, the metal substrate as an anode and the inert electrode as a cathode. And then taking out the metal base material, washing the metal base material by pure water, and finally drying. In some embodiments, the fluorine-containing acid solution is a mixture of an oxyacid and a fluorine-free acid salt. In other embodiments, the fluorine-containing acid solution is formed by mixing an aqueous hydrogen fluoride solution and an oxyacid. Wherein, the oxyacid can be selected from any one of phosphoric acid, sulfuric acid, oxalic acid and the like, and the concentration of the oxyacid in the electrolyte can be between 0.1mol/L and 1 mol/L. The oxygen-free acid salt of fluorine may be sodium fluoride, potassium fluoride, etc., and is selected according to actual needs, but the concentration of fluorine particles in the electrolyte is between 0.15mol/L and 0.3 mol/L.

Next, an electrolyte solution for electrochemical deposition is prepared.

The phosphate used in the preparation of the electrolyte is a soluble phosphate, for example, ammonium hydrogen phosphate, ammonium dihydrogen phosphate, etc., and similarly, the calcium salt used in the preparation of the electrolyte is a soluble calcium salt, for example, calcium acetate, calcium nitrate, etc. The ratio of calcium to phosphorus in the electrolyte is (1.6-1.7):1, preferably the ratio of calcium to phosphorus is 1.67:1, more specifically, in the embodiment of the invention, the concentration of calcium ions in the electrolyte can be specifically between 1.67mmol/L and 5mmol/L, and the concentration of phosphorus atoms is between 1mmol/-3 mmol/L. The concentration of hydrogen peroxide in the electrolyte may be between 6% and 12% by volume.

When the electrolyte is prepared, the conductivity and the pH of the electrolyte are required to be regulated and controlled. The pH of the prepared electrolyte is preferably 5-6.5, and the conductivity can be between 1500 muS/cm and 2000 muS/cm.

In this embodiment, the conductivity of the electrolyte may be enhanced by adding an ionic compound to the electrolyte. In an exemplary embodiment, the ionic compound is ammonium chloride, and the concentration of the ammonium chloride in the electrolyte is between 1mmol/L and 5 mmol/L. In practice, other ionic compounds such as sodium chloride, potassium chloride, etc. can be used to control the conductivity of the electrolyte, as long as the conductivity of the electrolyte can reach a predetermined value. However, it should be noted that the calcium-phosphorus ratio in the electrolyte should not change after the ionic compound is added to the electrolyte, and insoluble precipitates should not be formed in the electrolyte. In addition, hydrochloric acid, ammonia water, or the like may be used to adjust the pH according to the actual conditions. It is understood that the conductivity and pH described in this example are both measured at room temperature (i.e., ambient temperature), which is typically 20 deg.C to 30 deg.C, such as 20 deg.C, 25 deg.C, etc.

Further, when the electrolyte is prepared, inert gas can be introduced into the electrolyte to discharge carbon dioxide in the electrolyte. The inert gas may be nitrogen or other gas that does not participate in the reaction.

Then, electrochemical deposition is carried out in the electrolyte to form an HA coating on the surface of the metal substrate.

The specific method of electrochemical deposition comprises the following steps: intermittently introducing direct current with constant current with the current density of 20mA/cm between the metal substrate and the inert electrode such as platinum net, graphite and the like at the temperature of 25-70 ℃ to react²-50mA/cm². That is, when the electrochemical deposition reaction is performed, the current is first applied to the electrodes and then the current is cut off, and the operations of applying and cutting off the current are performed at least twice. Typically, the power-on and power-off operations are repeated less than or equal to ninety times. Optionally, the duration of each power-on is between 10s-300s, and the duration of each power-off is between 10s-300 s. Optionally, the total duration of the energization can be controlled from 180s to 900s throughout the process in order to obtain a suitable thickness of the HA coating.

Optionally, during the electrochemical deposition, the electrolyte may be stirred to remove bubbles in the electrolyte and promote the exchange of substances in the electrolyte, thereby improving the efficiency of the reaction. Alternatively, in the case of a metal substrate having a three-dimensional structure such as a void formed on the surface thereof, the electrolyte solution may be subjected to pressure reduction and degassing during the electrochemical deposition.

The current used in this example HAs a higher current density, which shortens the time of electrochemical deposition and improves the purity and crystallinity of the finally obtained HA particles. And by intermittently introducing current between the electrodes, the generation of hydrogen in the reaction process is further inhibited, so that the bonding force between the HA coating and the surface of the metal substrate is improved. The thickness of the coating can be conveniently controlled by controlling the single electrifying time and the total electrifying time in the electrochemical deposition process, so that the ultrathin HA coating can be obtained on the surface of the metal substrate.

Preferably, after the electrochemical deposition is finished, post-treatment is also included. The post-treatment process comprises the following steps: firstly, soaking the metal substrate deposited with the HA coating in pure water for washing; then, immersing into alkaline solution to further promote crystallization of the deposited HA particles; then, soaking the fabric into pure water for washing; finally, after drying the surface moisture, the mixture was placed in an oven and dried at 60 ℃. The alkaline solution is generally a dilute solution, such as a low concentration (e.g. 1mol/L) sodium hydroxide solution, a potassium hydroxide solution, or a dilute solution of a strong base and a weak acid salt such as sodium carbonate and potassium carbonate, and the embodiments of the present invention are not limited thereto.

Hereinafter, preferred examples of the method for depositing hydroxyapatite on the metal surface will be described in detail by using specific examples, but the following examples should not limit the present invention.