阅读说明：本技术 一种纳米金刚石增强生物镁合金及其制备方法 (Nano-diamond enhanced biological magnesium alloy and preparation method thereof ) 是由 刘龙 于 2021-09-03 设计创作，主要内容包括：本发明公开了一种纳米金刚石增强生物镁合金及其制备方法,该制备方法包括按设定比例配取纳米金刚石颗粒和镁合金基体粉末；将配取的粉末放入球磨机中,在保护气氛下进行球磨,得到分散均匀的混合粉末；以步骤一得到的混合粉末为原料,在保护气氛下,采用选择性激光熔化技术制得含有纳米金刚石的生物镁合金,该制备方法既能保证并保持金刚石结构的完整性,又能避免纳米金刚石的团聚,保证这些纳米增强体颗粒在基体中能得到有效的分散,从而制备得到合格的材料,以满足其在实际状况下的应用。(The invention discloses a nano-diamond enhanced biological magnesium alloy and a preparation method thereof, wherein the preparation method comprises the steps of preparing nano-diamond particles and magnesium alloy matrix powder according to a set proportion; putting the prepared powder into a ball mill, and performing ball milling under protective atmosphere to obtain uniformly dispersed mixed powder; the mixed powder obtained in the step one is used as a raw material, and the biological magnesium alloy containing the nano-diamond is prepared by adopting a selective laser melting technology under a protective atmosphere.)

1. A preparation method of a nano-diamond enhanced biological magnesium alloy is characterized by comprising the following steps:

step one, preparing nano diamond particles and magnesium alloy matrix powder according to a set proportion; putting the prepared powder into a ball mill, and performing ball milling under protective atmosphere to obtain uniformly dispersed mixed powder; wherein the content of the nano-diamond particles in the mixed powder is 1.5-8.5 wt%;

step two, taking the mixed powder obtained in the step one as a raw material, and preparing the biological magnesium alloy containing the nano-diamond by adopting a selective laser melting technology under a protective atmosphere; wherein the content of the first and second substances,

when selective laser melting is carried out, the laser power is controlled to be 60-100W, the scanning speed is controlled to be 160mm/min and 120-100 mu m, the scanning interval is 80-100 mu m, the powder spreading thickness is controlled to be 250 mu m and the spot diameter is 90-110 mu m.

2. The method of claim 1, wherein: the particle size of the nano diamond particles is 4-10 nm.

3. The method of claim 1, wherein: the particle size of the magnesium alloy matrix powder is 60-100 mu m.

4. The production method according to claim 3, characterized in that: the magnesium alloy matrix powder adopts ZK60 alloy powder.

5. The method of claim 1, wherein: during ball milling, the ball-material ratio is 8:1-12:1, the rotating speed is 1000-.

6. The method of claim 5, wherein: the ball-material ratio is 10:1, the rotating speed is 1500r/min, and the ball milling time is 3 hours.

7. The method of claim 1, wherein: and argon is used for protection during ball milling.

8. The method of claim 1, wherein: the content of the nano-diamond particles in the mixed powder is 2.5 to 6.5 wt%.

9. The production method according to any one of claims 1 to 8, characterized in that: when selective laser melting is carried out, the laser power is controlled to be 80W, the scanning speed is 150mm/min, the scanning interval is 90 mu m, the powder spreading thickness is 200 mu m, and the spot diameter is 100 mu m.

10. A nano-diamond enhanced biological magnesium alloy is characterized in that: prepared by the preparation method of any one of claims 1 to 9.

Technical Field

The invention belongs to the technical field of magnesium-based composite material preparation, and particularly relates to a nano-diamond enhanced biological magnesium alloy and a preparation method thereof.

Background

The magnesium alloy is a very potential orthopedic biomedical material. On one hand, the magnesium alloy has the elastic modulus similar to that of human bones, can effectively inhibit the stress shielding effect and avoid the delayed bone healing or the occurrence of secondary fracture caused by bone mass deficiency. On the other hand, the magnesium alloy can be gradually degraded in a human body without a secondary operation of taking out, and the degradation product magnesium ions can promote the proliferation and differentiation of bone cells and accelerate the healing of bone tissues. However, because the electrode potential of magnesium is low, the corrosion degradation tendency in a physiological environment is high, and a degradation product film formed by degradation is loose and porous, so that a matrix is not protected, and the magnesium alloy is degraded too fast in a human body. Degradation products formed by too rapid degradation are not as readily absorbed by surrounding tissues, resulting in local tissue overbasing or the formation of subcutaneous hydrogen cysts, which in turn can lead to tissue inflammation or even necrosis. In addition, the rapid degradation causes the magnesium alloy implant to have rapid decrease of mechanical properties, early loss of mechanical integrity, and influence on the growth and healing of damaged tissues. Therefore, how to improve the corrosion resistance of the magnesium alloy is a difficult problem which needs to be solved urgently as an orthopedic biomedical material.

The nano diamond is a diamond particle with the particle size of 1-100nm, has the characteristics of diamond and nano materials, for example, because carbon atoms in the diamond are all combined by covalent bonds, the nano diamond has the chemical properties of high hardness, high insulation, biocompatibility and stability of the diamond, and simultaneously has the characteristics of large specific surface area, high surface activity and the like of the nano materials because the particle size of the nano diamond is nano scale. More importantly, the surfaces of the nano-diamond particles also have rich oxygen-containing functional groups (carbonyl, carboxyl and the like), the nano-diamond particles are negatively charged after the functional groups are hydrolyzed, and the deposition of calcium ions and phosphate ions in body fluid is hopeful to be promoted through physical adsorption and chemical adsorption in the environment of body fluid of a human body to form a calcium-phosphorus compound. If the nano diamond can be compounded in the magnesium alloy matrix, a compact and insoluble calcium-phosphorus compound protective layer is hopefully formed by promoting the deposition of the calcium-phosphorus compound on the surface of the magnesium alloy, and the degradation resistance of the biomedical magnesium alloy is obviously improved.

However, due to the high surface energy of the nano-diamond, the van der waals force and electrostatic adsorption among the nano-particles, the nano-structure is volatilized due to the agglomeration among the particles, pores and cracks are easy to initiate after the nano-diamond is formed, and the mechanical property and the degradation resistance are greatly reduced; in addition, the conventional preparation methods such as smelting-casting, discharge plasma sintering method, thermal deformation method and the like in the prior art cannot exert the strengthening effect of the nano-diamond due to high temperature and long heat preservation time in the preparation process and extremely easy damage to the structure of the nano-diamond crystal in the forming process.

In summary, it is highly desirable to develop a suitable preparation method to overcome the disadvantages of the conventional addition method.

Disclosure of Invention

The invention mainly aims to provide a nano-diamond enhanced biological magnesium alloy and a preparation method thereof, wherein the preparation method can ensure and maintain the integrity of a diamond structure, avoid the agglomeration of nano-diamond and ensure that nano-enhanced particles can be effectively dispersed in a matrix, so that qualified materials are prepared and can meet the application requirements of the nano-diamond enhanced biological magnesium alloy under actual conditions.

Therefore, the preparation method of the nano-diamond enhanced biological magnesium alloy provided by the embodiment of the invention comprises the following steps:

step one, preparing nano diamond particles and magnesium alloy matrix powder according to a set proportion; putting the prepared powder into a ball mill, and performing ball milling under protective atmosphere to obtain uniformly dispersed mixed powder; wherein the content of the nano-diamond particles in the mixed powder is 1.5-8.5 wt%;

step two, taking the mixed powder obtained in the step one as a raw material, and preparing the biological magnesium alloy containing the nano-diamond by adopting a selective laser melting technology under a protective atmosphere; wherein the content of the first and second substances,

when selective laser melting is carried out, the laser power is controlled to be 60-100W, the scanning speed is controlled to be 160mm/min and 120-100 mu m, the scanning interval is 80-100 mu m, the powder spreading thickness is controlled to be 250 mu m and the spot diameter is 90-110 mu m.

Specifically, the particle size of the nano diamond particles is 4-10 nm.

Specifically, the particle size of the magnesium alloy matrix powder is 60-100 μm.

Specifically, ZK60 alloy powder is adopted as the magnesium alloy matrix powder.

Specifically, during ball milling, the ball-material ratio is 8:1-12:1, the rotating speed is 1000-.

Specifically, the ball-material ratio is 10:1, the rotating speed is 1500r/min, and the ball milling time is 3 hours.

Specifically, argon is used for protection during ball milling.

Specifically, the content of the nanodiamond particles in the mixed powder is 2.5 to 6.5 wt%.

Specifically, during selective laser melting, the laser power is controlled to be 80W, the scanning speed is 150mm/min, the scanning interval is 90 μm, the powder spreading thickness is 200 μm, and the spot diameter is 100 μm.

Therefore, according to another aspect of the embodiment of the invention, the nano-diamond enhanced biological magnesium alloy is prepared by the preparation method.

Compared with the prior art, at least one embodiment of the invention has the following beneficial effects:

according to the invention, the nano-diamond is compounded into the biological magnesium alloy through the selective laser melting technology for the first time, on the premise of ensuring the integrity of the original structure of the nano-diamond, the corrosion resistance of the magnesium alloy is improved by controlling the using amount and the distribution mode of the nano-diamond, and meanwhile, the nano-diamond has the characteristics of high strength and high hardness of diamond, so that the nano-diamond has the effect of nano hard phase dispersion strengthening in the magnesium alloy, and the mechanical property of the magnesium alloy is enhanced.

According to the invention, by optimizing the ball milling process parameters, the uniform mixing of the nano diamond particles and the magnesium alloy matrix powder is realized; this provides the necessary condition for obtaining the biological magnesium alloy with uniformly distributed nano diamond particles. After the ball milling is finished, a selective laser melting process with a specific parameter range is assisted, and the characteristics of rapid melting and rapid solidification of the selective laser melting process are utilized, so that the problem of structural damage of the nano-diamond under the action of long-time high temperature is successfully solved.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

FIG. 1(a) is a microstructure of a pure ZK60 magnesium alloy prepared by laser melting;

FIG. 1(b) is a microstructure of a biological magnesium alloy prepared in example 1;

FIG. 2(a) is a diagram of the degraded morphology of a pure ZK60 magnesium alloy prepared by laser melting;

FIG. 2(b) is a diagram showing the degraded morphology of the biomagnesium alloy prepared in example 1.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

The raw materials are nano diamond powder (the granularity is 4-10nm) and ZK60 alloy powder (the granularity is 60-100 mu m), 5g of nano diamond powder and 95g of ZK60 alloy powder are weighed and put into a ball mill for ball milling under the protection of argon gas, wherein the ball-material ratio is 10:1, the rotating speed of the ball mill is 1500rad/min, and the ball milling is carried out for 3 hours. After the ball milling is finished, preparing the biological magnesium alloy containing the nano diamond by a laser melting technology under a protective atmosphere. And during selective laser melting, controlling the laser power to be 80W, the scanning speed to be 150mm/min, the spot diameter to be 100 mu m, the scanning interval to be 90 mu m and the powder spreading thickness to be 200 mu m to prepare the biological magnesium alloy added with the nano diamond.

Microstructure morphology and Raman spectrum results show that the nano-diamond has a complete structure after SLM forming and is uniformly dispersed in a magnesium metal matrix (shown in figure 1 b); the electrochemical test result shows that the corrosion current of the magnesium alloy is 44.2 mu A/cm from ZK60²The reduction is 10.73μA/cm²The weight loss results show that the corrosion rate of the ZK60 alloy is reduced from 1.6mm/year to 0.5mm/year after the addition of the nano diamond; analysis of the alloy degradation product composition and morphology revealed that the surface of ZK60 alloy with added nanodiamonds formed a uniform apatite layer (fig. 2 b). Furthermore, the compressive strength of ZK60 was increased from 131.6MPa to 191 MPa. Compared with ZK60, the prepared Mg-ND nanocomposite has significantly improved corrosion resistance and compressive strength. The microstructure diagram and the degraded morphology diagram of the pure ZK60 magnesium alloy prepared by laser melting are respectively shown in FIG. 1(a) and FIG. 2 (a).

Example 2

The raw materials are nano diamond powder (the granularity is 4-10nm) and ZK60 alloy powder (the granularity is 60-100 mu m), 5g of nano diamond powder and 95g of ZK60 alloy powder are weighed, the ball-material ratio is 10:1 under the protection of argon gas, the rotating speed of a ball mill is 1500rad/min, and the ball milling is carried out for 3 hours. After the ball milling is finished, preparing the biological magnesium alloy containing the nano diamond by a laser melting technology under a protective atmosphere. And during selective laser melting, controlling the laser power to be 90W, the scanning speed to be 120mm/min, the spot diameter to be 100 mu m, the scanning interval to be 80 mu m and the powder spreading thickness to be 240 mu m, and preparing the biological magnesium alloy added with the nano diamond.

Microstructure morphology and Raman spectrum results show that the nano-diamond has a complete structure after SLM forming and is uniformly dispersed in a magnesium metal matrix; the electrochemical test result shows that the corrosion current of the magnesium alloy is reduced from 44.2 mu A/cm2 of ZK60 to 16.32 mu A/cm2, and the weight loss result shows that the corrosion rate of the ZK60 alloy is reduced from 1.6mm/year to 0.8mm/year after the nano diamond is added; analysis of the composition and morphology of the alloy degradation products revealed that the surface of ZK60 alloy with nanodiamond added formed a uniform apatite layer. Furthermore, the compressive strength of ZK60 increased from 131.6MPa to 178 MPa. Compared with ZK60, the prepared Mg-ND nanocomposite has significantly improved corrosion resistance and compressive strength.

Example 3

The raw materials are nano diamond powder (the granularity is 4-10nm) and ZK60 alloy powder (the granularity is 60-100 mu m), 3g of nano diamond powder and 97g of ZK60 alloy powder are weighed, the ball-material ratio is 11:1 under the protection of argon gas, the rotating speed of a ball mill is 1200rad/min, and the ball milling is carried out for 2 hours. After the ball milling is finished, preparing the biological magnesium alloy containing the nano diamond by a laser melting technology under a protective atmosphere. And during selective laser melting, controlling the laser power to be 100W, the scanning speed to be 160mm/min, the spot diameter to be 90 mu m, the scanning interval to be 100 mu m and the powder spreading thickness to be 160 mu m to prepare the biological magnesium alloy added with the nano diamond.

Microstructure morphology and Raman spectrum results show that the nano-diamond has a complete structure after SLM forming and is uniformly dispersed in a magnesium metal matrix; the electrochemical test result shows that the corrosion current of the magnesium alloy is reduced from 44.2 mu A/cm2 of ZK60 to 13.11 mu A/cm2, and the weight loss result shows that the corrosion rate of the ZK60 alloy is reduced from 1.6mm/year to 0.7mm/year after the nano diamond is added; analysis of the composition and morphology of the alloy degradation products revealed that the surface of ZK60 alloy with nanodiamond added formed a uniform apatite layer. Furthermore, the compressive strength of ZK60 increased from 131.6MPa to 185 MPa.

Comparative example 1

The difference from the embodiment 1 is that the laser power is controlled to be 110W during sintering, the scanning speed is 170mm/min, and the powder spreading thickness is 240 μm; microstructure morphology and Raman spectrum results show that partial nano-diamond is carbonized after the nano-diamond is shaped by the SLM to form magnesium alloy carbide, the power is overhigh, the energy density is overhigh, the temperature of metal melt is overhigh and the nano-diamond particles can be carbonized at overhigh temperature as allotropes of carbon elements; the electrochemical test result shows that the corrosion current of the magnesium alloy is reduced from 44.2 mu A/cm2 of ZK60 to 40.11 mu A/cm2, and the weight loss result shows that the corrosion rate of the ZK60 alloy is reduced from 1.6mm/year to 1.5mm/year after the nano diamond is added; analysis of the composition and morphology of the alloy degradation products revealed that a small amount of apatite layer was formed on the surface of the ZK60 alloy to which nanodiamond was added. Furthermore, the compressive strength of ZK60 increased from 131.6MPa to 158.3 MPa. The deterioration of corrosion resistance and strength is mainly attributed to that the carbonized nanodiamond does not have the characteristics of diamond, the carbonized nanodiamond serving as a cathode phase of galvanic corrosion in the magnesium alloy aggregate accelerates the corrosion of the magnesium alloy, and the carbonized nanodiamond has low strength and cannot play a role in dispersion strengthening.

Comparative example 2

The difference from the example 1 is that 10g of nano-diamond powder and 90g of ZK60 alloy powder are weighed, the microstructure morphology and Raman spectrum results show that the nano-diamond has complete structure after SLM forming, nano-diamond agglomerates exist in a magnesium metal matrix to form gaps, electrostatic adsorption among nano-diamond particles is enhanced due to the large specific surface area of the nano-diamond particles when the nano-diamond particles are too many, the agglomerates are generated in the forming process, electrochemical test results show that the corrosion current of the magnesium alloy is reduced to 31.51 muA/cm 2 from 44.2 muA/cm 2 of ZK60, and weight loss results show that the corrosion rate of the ZK60 alloy is reduced to 1.4mm/year from 1.6mm/year after the nano-diamond is added; analysis of the composition and morphology of the alloy degradation products revealed that the surface of the ZK60 alloy with the added nanodiamond formed a apatite layer, but the corrosion products were highly non-uniform and had voids. Furthermore, the compressive strength of ZK60 was increased from 131.6MPa to 144.7 MPa.

Comparative example 3

Compared with the embodiment 1, the difference is that the laser power is controlled to be 40W during sintering, the scanning speed is 110mm/min, the powder spreading thickness is 140 micrometers, and the microstructure morphology and Raman spectrum result show that the nano-diamond has a complete forming structure in the SLM, but the prepared alloy has more gaps, and the metal powder cannot be completely melted and formed due to the fact that the power is too low, the laser energy received by the powder is less; electrochemical test results show that the corrosion current of the magnesium alloy is reduced from 44.2 mu A/cm2 of ZK60 to 54.11 mu A/cm2, and weight loss results show that the corrosion rate of the ZK60 alloy is reduced from 1.6mm/year to 3.1mm/year after the nano-diamond is added. Furthermore, the compressive strength of ZK60 increased from 131.6MPa to 116.5 MPa.

The above examples are merely illustrative for clearly illustrating the present invention and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. Nor is it intended to be exhaustive of all embodiments. And obvious variations or modifications of the invention may be made without departing from the scope of the invention.