An activated carbide nanoparticle-reinforced magnesium alloy composite material and its preparation method

Abstract

The present invention relates to an activated carbide nanoparticle-reinforced magnesium alloy composite material and a preparation method thereof. The composite material is composed of a magnesium matrix and activated carbide nanoparticles uniformly distributed in the grain gaps of the magnesium matrix; the mass fraction of the nanoparticles in the material is 1.8% to 10%; the magnesium metal is pure magnesium or magnesium alloy MgM; in the preparation, pulsed laser surface activation technology is used to activate the surface of the carbide nanoparticles, so as to change the state of the nanoparticles, change the surface energy of the particles, and change their wettability in the molten magnesium metal; then the nanoparticles are added to the molten magnesium metal to improve the mechanical strength of the magnesium metal. The present invention has the advantages of simple process, convenient operation, and the prepared composite material shows excellent performance in terms of mechanical properties and biocompatibility, etc.

Description

Technical Field

[0001] The present invention relates to an activated carbide nanoparticle-reinforced magnesium alloy composite material and a preparation method thereof, which are generally applied to the field of biodegradable magnesium-based metal biomedical devices, including bioabsorbable vascular stents, bioabsorbable ureteral stents, degradable bone implants with adjustable modulus, guided bone regeneration membranes, bioabsorbable dental membranes, and other biomedical implants. Background Art

[0002] In the field of biomedical applications, traditional metallic biomaterials (e.g., stainless steel, titanium alloy, zirconium alloy) have been widely used clinically, but there are some obvious problems. The existing metallic materials used clinically are inert materials and cannot degrade, so they need to be removed surgically after the affected area has healed. Therefore, in recent years, new biodegradable metallic materials for biomedical use have been developed, including magnesium-based alloys, zinc-based alloys, and iron-based alloys. Among them, magnesium-based materials are considered to be the most promising biodegradable metallic materials because their elastic modulus is similar to that of human bones, and they have good biocompatibility and self-degradable properties. However, the poor plasticity, wear resistance, and corrosion resistance of magnesium alloys seriously hinder their widespread application.

[0003] Currently, the general understanding of magnesium alloy biomedical materials is to improve their mechanical properties and corrosion resistance. Among them, the particle-reinforced magnesium matrix composite material preparation technology is often used. By utilizing the advantages of high modulus, high hardness, high melting point, and high stability of the reinforcement, the comprehensive properties such as strength, wear resistance, and corrosion resistance of magnesium alloys are improved through the synergistic effect of the reinforcement and the matrix structure. For example, Patent CN109518101A provides a preparation method of a magnesium alloy material, which mainly obtains a high-strength magnesium alloy material by changing the material composition and adding various additives such as tungsten carbide, carbon fiber, and nano-boron fiber, overcoming the problem of insufficient strength of magnesium alloys. However, it fails to solve the poor wettability between ceramic particles and the matrix or the occurrence of adverse interfacial reactions, which will lead to weak interfacial bonding strength between the matrix and ceramic particles, thereby causing a decrease in the plasticity of the composite material. The existence of a poor interface will also lead to an accelerated degradation ability, affecting the biological safety of magnesium alloys. Patent CN116144958A provides a method for strengthening magnesium alloys with nanoparticles, in which zirconium (Zr)-coated NbB2 nanoparticles are added during the casting of magnesium alloys, and ultrasonic dispersion-assisted casting of magnesium alloys is carried out. This method of surface coating with metal improves the wettability between nanoparticles and the metal melt, and ultrasonic assistance can solve the problem of uneven dispersion caused by the agglomeration of nanoparticles in the metal melt to a certain extent. However, there is a problem of energy decay of ultrasound in the solution, which will cause uneven distribution of nanoparticles in some positions, and the zirconium coating method increases the content of impurity elements in the alloy, which will affect the degradation ability of magnesium alloys. Summary of the Invention

[0004] The object of the present invention is to provide an activated nanoparticle-reinforced magnesium alloy composite material and a preparation method thereof for the problem that in the current technology, the wettability of nanoparticles and the matrix melt in the molten state of nanoparticle-reinforced degradable magnesium alloys is poor, resulting in uneven dispersion of nanoparticles in the molten magnesium metal during the smelting process. This method mainly uses pulsed laser surface activation technology to activate the surface of carbide nanoparticles in an aqueous solution, changing the state of the nanoparticles, altering the surface energy of the particles, and changing their wettability in the molten magnesium metal; then adding the nanoparticles to the molten magnesium metal to improve the mechanical strength of the magnesium metal. Since the activated nanoparticles have good wettability with the matrix and better bonding with the matrix, they can not only greatly improve the mechanical strength and biocompatibility of the magnesium metal but also have the least impact on its degradation performance. The present invention has the advantages of simple process, convenient operation, and the prepared composite material shows excellent performance in terms of mechanical properties and biocompatibility, etc.

[0005] The technical solution of the present invention is as follows:

[0006] An activated carbide nanoparticle-reinforced magnesium metal composite material, which is composed of a magnesium metal matrix and activated carbide nanoparticles uniformly distributed in the grain gaps of the magnesium matrix; the mass fraction of nanoparticles in the material is 1.8% to 10%;

[0007] The magnesium metal is pure magnesium or magnesium alloy MgM, where M includes one or several of zinc (Zn), calcium (Ca), aluminum (Al), silver (Ag), copper (Cu), lithium (Li), zirconium (Zr), strontium (Sr), yttrium (Y), gadolinium (Gd), niobium (Nd), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), and scandium (Sc).

[0008] The diameter of the nanoparticles is about 10 to 500 nm;

[0009] In the magnesium alloy MgM, the mass percentage content of M is 0.1% - 3%.

[0010] The carbide nanoparticles are one or more of metal carbides and non-metal carbides.

[0011] The nanoparticles are one or more of tungsten carbide (WC), titanium carbide (TiC), niobium carbide (NbC), chromium carbide (Cr3C2), nickel carbide (NiC), vanadium carbide (VC), zirconium carbide (ZrC), silicon carbide (SiC), and boron carbide (B4C).

[0012] The activated carbide nanoparticles are subjected to laser surface activation treatment. The specific operation is as follows: Soak the nanoparticles in deionized water, then select a laser with a wavelength of 1064 nm, a power of 40 - 80 W, a linear velocity of 0.01 mm / s - 10 mm / s, a line spacing of 0.05 - 1 mm, and an irradiation time of 0.5 - 5 h. Then take out the activated carbide and dry it at 150 - 300 °C for 8 - 24 h;

[0013] Among them, the volume ratio of deionized water to carbide particles is 2:1 - 5:1.

[0014] A method for preparing an activated carbide nanoparticle-reinforced magnesium metal composite material, which includes the following preparation steps:

[0015] (1) Weigh pure magnesium and carbide raw materials respectively according to the designed ratio;

[0016] (2) Mix potassium hexafluoroaluminate (KAlF4) with the nanoparticles; where potassium hexafluoroaluminate accounts for 0.01% - 0.1% of the mass fraction of the carbide nanoparticles;

[0017] (3) Under the protection of an inert gas, first melt the pure magnesium ingot in a graphite crucible at 500 - 1000 °C; then add the mixture of potassium hexafluoroaluminate (KAlF4) and the nanoparticles, and then mechanically stir for 0.5 - 3 h to enter the molten magnesium;

[0018] (4) Cover the surface of the molten magnesium after adding the nanoparticles with a mixture of sodium chloride and potassium chloride. The mass ratio of sodium chloride to potassium chloride is 1:1, and the total addition amount accounts for 0.2% - 2% of the volume of the molten magnesium metal. Then continue to stir for 1 - 2 h, and then pour the melt into a mold and cool to obtain a magnesium metal composite material;

[0019] When the magnesium metal is a magnesium alloy, the following steps are also required: Add M-designed amount of MgM or intermediate metal M to the melt. At this time, the melting temperature is 500 - 1000 °C, mechanically stir for 0.5 - 3 h, and then pour the melt into a mold for cooling to obtain a composite metal;

[0020] (5) Roll the cast magnesium metal composite material at a temperature of 250 - 500 °C. The rolling pressure is 1 KN - 10 KN, the rolling speed is 0.1 - 10 mm / min, and the rolling deformation amount is 75 - 90%. Finally, an activated carbide nanoparticle-reinforced magnesium metal composite material is obtained.

[0021] The inert gas used in the above method is a mixed gas protected by 99% argon gas and 1% sulfur hexafluoride gas.

[0022] The substantial features of the present invention are as follows:

[0023] In the present invention, by adding activated carbide nanoparticles into a magnesium matrix, due to the good wettability between the activated carbide nanoparticles and the matrix, the occurrence of adverse interfacial reactions between the carbide and the magnesium metal matrix is reduced, the interfacial bonding degree between the matrix and the nanoparticles is increased, and the nanoparticles can be evenly distributed in the matrix after activation and are not prone to agglomeration, effectively hindering the growth of magnesium metal grains, resulting in grain refinement and greatly improving the mechanical properties of magnesium metal. Among them, the activation process of the carbide nanoparticles affects the wetting effect between the nanoparticles and the magnesium matrix in the melt, and thus affects their dispersibility in the matrix. The carbide nanoparticles treated by laser activation can be well melted with the magnesium matrix and can be evenly dispersed in the matrix with the assistance of mechanical stirring, reducing agglomeration. Through experiments, under the process of this patent, first activating the carbide nanoparticles can enable the nanoparticles to have a high wettability with the metal during the casting process of magnesium metal, and then using mechanical stirring can make the nanoparticles more evenly dispersed in the metal melt, ensuring the stability of the performance of the prepared metal composite material.

[0024] The beneficial effects of the present invention are as follows:

[0025] In the present invention, by the method of laser-activating nanoparticles, the activated carbide nanoparticles are evenly dispersed into the magnesium metal matrix, and a kind of activated carbide nanoparticle-reinforced magnesium metal composite material is prepared, specifically as follows:

[0026] (1) The nanoparticles are evenly dispersed and there is no aggregation. The activated carbide is evenly distributed in the matrix. In the present invention, a kind of activated carbide nanoparticle-reinforced magnesium alloy composite material is prepared by laser activation treatment. The laser activation treatment of the carbide nanoparticles in an aqueous solution improves the wettability between the nanoparticles and the matrix, reduces the agglomeration of the particles, improves their uniformity in the matrix, and reduces particle aggregation.

[0027] (2) The elastic modulus can be adjusted. A kind of activated carbide nanoparticle-reinforced magnesium alloy composite material prepared by laser activation in the present invention can change the elastic modulus of the matrix by adjusting the size and added content of the nanoparticles, making the elastic modulus of the magnesium alloy adjustable. This is very meaningful in the field of degradable biomaterials, especially in the application of bone implants, where it can match the modulus of local bone materials to achieve a more ideal treatment effect.

[0028] (3) Improvement in mechanical properties. A magnesium alloy composite material reinforced with activated carbide nanoparticles prepared by laser activation according to the present invention, by adding well-dispersed activated carbide nanoparticles, the nanoparticles are uniformly present in the magnesium metal matrix, hindering the movement of dislocations and restricting the growth of grains, achieving the strengthening purpose. The yield strength of the composite material under the optimal parameters of the present invention is 121 Mpa, and the tensile strength is 148 MPa. Compared with the yield strength (68 MPa) and tensile strength (89 MPa) of magnesium metal under the same process, they are increased by 77.94% and 66.29% respectively.

[0029] (4) Improvement in creep, hardness and fatigue resistance. A magnesium metal composite material reinforced with activated carbide nanoparticles by laser activation according to the present invention, wherein the added nanoparticles can improve the fatigue life of the magnesium-containing matrix by reducing the effective stress on the matrix, and the unique high hardness of the nanoparticles can be combined with the hardness of the magnesium-based material, thereby further increasing the hardness of the matrix. Compared with the hardness of 46 HV of magnesium metal, the hardness of the material prepared according to the present invention is 60 HV, an increase of 30.43%.

[0030] (5) Reduction in the size of intermetallic phases in magnesium alloys: The dispersed nanoparticles can inhibit the growth of intermetallic phases during solidification and at the same time control the growth of grains. The reduction in grain size ultimately improves the ductility of magnesium alloys. The grain size of magnesium alloys is reduced from the initial 25.3 μm to 8.5 μm, a reduction of 66.40%. And the ductility increases to 9.8%, compared with 8.5% of magnesium metal, the ductility is increased by 15.29%.

[0031] (6) Maintaining good biocompatibility and moderate corrosion rate of magnesium metal. A magnesium metal composite material reinforced with activated carbide nanoparticles prepared by laser activation according to the present invention, the dispersed nanoparticles have high reaction stability and thermal stability, and the magnesium-based material including the nanoparticles will not reduce the loss of biocompatibility and the increase in the rate of biological corrosion.

[0032] (7) Good imaging property. A magnesium alloy composite material reinforced with activated carbide nanoparticles prepared by laser activation treatment according to the present invention, the dispersed carbide nanoparticles are non-magnetic, which enables magnetic resonance imaging examination of soft tissues near implants made of carbide without artifacts. Description of the Drawings

[0033] Figure 1 For the dispersion of unactivated and activated carbide nanoparticles in the magnesium metal composite material obtained in Example 1 and Comparative Example 1;

[0034] Figure 2Comparison chart of the mechanical properties of the activated carbide nanoparticle-reinforced magnesium alloy composites obtained in Example 1, Comparative Example 1, and Example 2;

[0035] Figure 3 Comparison chart of the Vickers hardness of the activated carbide nanoparticle-reinforced magnesium alloy composites obtained in Example 1, Comparative Example 1, and Example 2;

[0036] Figure 4 Comparison chart of the corrosion rates of the activated carbide nanoparticle-reinforced magnesium alloy composites obtained in Example 1, Comparative Example 1, and Example 2;

[0037] Figure 5 Comparison chart of the grain sizes of the activated carbide nanoparticle-reinforced magnesium alloy composites obtained in Example 1, Comparative Example 1, and Example 2;

[0038] Figure 6 Comparison chart of the cell viability of the activated carbide nanoparticle-reinforced magnesium alloy composites obtained in Example 1, Comparative Example 1, and Example 2. Detailed implementation manners

[0039] The present invention will be further described in detail below through specific examples.

[0040] Example 1

[0041] Preparation and performance testing of the activated tungsten carbide nanocomposite magnesium metal material.

[0042] The test methods adopted in this example are as follows:

[0043] Mechanical testing: Conducted using a universal tensile testing machine with model number. The specific parameters and sample sizes of the experiment comply with the national standard GBT228.1-2010

[0044] Vickers hardness: Conducted using a hardness tester with model number HMV-2T. The automatic loading running time of the experiment is 15 s, and the load is HV0.2 (1.96 N).

[0045] In vitro corrosion: The corrosion rate is measured using a thin slice with a sample diameter of 10 mm and a thickness of 2 mm, and carried out according to the specific requirements of the national standard GBT16886 in simulated body fluid

[0046] Grain size: The pictures taken by a DM2700 metallographic microscope are statistically analyzed using imageJ software

[0047] Cytotoxicity test: Conducted by the method of extraction solution. The extraction solution uses 1.25 cm 2The ratio of the surface area of 1 mL to the volume of the DMEM solution was extracted, then filtered through a filter membrane, and then serum was added to prepare the extract required for cell culture. MC3T3-E1 cells were used, and the culture medium was changed every other day. The cell viability test was carried out after 7 days of culture.

[0048] 1) Magnesium metal raw materials and carbide raw materials were weighed separately. The metal raw materials included pure magnesium (purity 99.95%). In this example, the composition used was magnesium metal particles with a mass fraction of about 97.7% and WC nanoparticles with a mass fraction of about 2.3% and a diameter of about 300 nm.

[0049] 2) Tungsten carbide was immersed in a glass petri dish filled with deionized water. The volume ratio of the solution to the added carbide was 2:1. Then, a laser with a wavelength of 1064 nm and a power of 40 W was selected, and galvanometer control was used. The linear velocity was 0.01 mm / s, the line spacing was 0.1 mm, and irradiation was carried out for 3 h. Then, the activated carbide was taken out and vacuum dried at 200 °C for 24 h.

[0050] 3) The activated tungsten carbide nanoparticles and potassium hexafluoroaluminate (KAlF4) with a mass ratio of 0.05% to tungsten carbide were uniformly mixed to obtain a mixture. The powder mixture was mixed by a mechanical shaker at about 300 rpm for about 30 min.

[0051] 4) Under the protection of an inert gas, high-purity magnesium ingots were melted in a graphite crucible at 650 °C. Then, the mixture of potassium hexafluoroaluminate (KAlF4) and activated tungsten carbide was added. The molten potassium hexafluoroaluminate was used to assist the incorporation of activated tungsten carbide particles, and then it was mechanically stirred into the molten magnesium;

[0052] 5) A mixture of sodium chloride and potassium chloride with a mass ratio of 1:1 was added. The volume of the mixture was 0.5% of the volume of the added pure magnesium melt to protect the magnesium alloy melt from oxidation. Then, stirring was continued for 1 h, and the melt was poured into a mold to cool.

[0053] 6) The as-cast magnesium metal composite material was rolled at a temperature of 300 °C. The rolled samples were taken perpendicular to the casting mold wall. The rolling pressure was 5 KN, the rolling speed was 3 mm / min, and the rolling deformation was 85%. Finally, an activated carbide nanoparticle-reinforced magnesium metal composite material was obtained.

[0054] 7) The prepared material was cut into samples of suitable size for subsequent mechanical, compositional, and biocompatibility tests.

[0055] After testing, in the magnesium metal matrix with activated tungsten carbide nanoparticles with a mass fraction of about 2.3% and a diameter of about 300 nm, as Figure 1As shown, the uniformity of the activated nanoparticles is significantly better than that of the unactivated particles. As Figure 2 shown, the mechanical strength of the magnesium metal with added activated nanoparticles has been improved. The yield strength is 89 MPa and the tensile strength is 106 MPa. This is mainly related to the uniform distribution of the activated nanoparticles. Since the nanoparticles have undergone laser surface activation treatment, the surface energy of the particles has been changed, affecting their wettability in the molten magnesium, making it not easy to agglomerate under mechanical stirring and being uniformly dispersed in the molten magnesium, playing the role of pinning sites and effectively preventing the growth of magnesium grains, thus improving the mechanical strength. As Figure 3 shown, the hardness of the metal with added nanoparticles is 53 HV, showing a certain improvement. Since the existing tungsten carbide nanoparticles themselves have high strength, the hardness of the magnesium metal has also been increased. As Figure 4 shown, the corrosion rate of the metal with added nanoparticles has not increased significantly. The corrosion rate is 3.81 μg / mm for 14 days 2 , slightly lower than that of the metal without added nanoparticles, mainly because the content of the added nanoparticles is moderate and the nanoparticles are uniformly distributed. As Figure 5 shown, the cell activity of the magnesium metal with added activated tungsten carbide is 92%, which has been improved compared with that without addition. The degradation of the magnesium metal with added tungsten carbide nanoparticles is slightly lower than that without addition, making the environment in the cell culture medium more suitable for cell growth, thus promoting cell proliferation and improving the bioactivity of the material.

[0056] Comparative Example 1

[0057] The difference between this comparative example and Example 1 is that the activation operation of the nano tungsten carbide particles in Step 2 is not carried out, and the subsequent process is the same as that in Example 1.

[0058] After testing, in the magnesium metal matrix with about 2.3% mass fraction of unactivated tungsten carbide nanoparticles with a diameter of about 300 nm, as Figure 1 shown, obvious agglomeration of the nanoparticles occurred. As Figure 2 shown, the mechanical properties of the magnesium metal with added unactivated nanoparticles have decreased compared with those of the metal without added particles and the metal with added activated particles. The yield strength is 60 MPa and the tensile strength is 70 MPa. This is mainly related to the agglomeration of the unactivated nanoparticles. Since the nanoparticles have agglomerated and are not well dispersed in the molten magnesium, it has an adverse effect on the mechanical strength of the magnesium metal. As Figure 3As shown, the hardness of the metal after adding nanoparticles is 48 HV, which has been improved to a certain extent compared with the metal without adding nanoparticles, but is lower than that of the metal added with activated nanoparticles. This is mainly due to the influence of undispersed nanoparticles. The relatively high hardness of the nanoparticles themselves will increase the hardness of the metal, but due to poor dispersion, the degree of increase is limited. As Figure 4 shown, the corrosion rate is 4.0 μg / mm after 14 days 2 , because the nanoparticles failed to disperse well in the matrix, thus affecting the degradation ability of the magnesium metal and increasing its degradation rate. As Figure 5 shown, the cell viability is 80%, which is also due to the relatively high degradation rate, which affects the cell proliferation environment, affects cell growth, and reduces the bioactivity of the material.

[0059] Example 2

[0060] The difference between this example and Example 1 lies in Step 1. Magnesium metal raw materials and tungsten carbide raw materials are weighed separately. The metal raw materials include pure magnesium (purity of 99.95%). The composition used in this example is magnesium metal particles with a mass fraction of about 95.9% and WC nanoparticles with a mass fraction of about 4.1% and a diameter of about 300 nm. The subsequent processes are the same as those in Example 1.

[0061] After testing, magnesium metal added with activated tungsten carbide nanoparticles with a mass fraction of about 4.1% and a diameter of about 300 nm. As Figure 2 shown, the mechanical strength of the magnesium metal added with activated nanoparticles has been further improved. The yield strength is 121 MPa and the tensile strength is 148 MPa. This is mainly related to the uniform distribution of activated nanoparticles with a relatively high mass fraction. Since the nanoparticles have been treated by laser surface activation, the surface energy of the particles has been changed, affecting their wettability in molten magnesium, making them less likely to agglomerate under mechanical stirring and uniformly dispersed in the molten magnesium. Nanoparticles with a relatively high mass fraction can better play the role of pinning sites, effectively preventing the growth of magnesium grains, and thus further improving the mechanical strength. As Figure 3 shown, the hardness of the metal after adding nanoparticles is 60 HV, which has been improved to a certain extent. Due to the high strength of the tungsten carbide nanoparticles with a higher mass fraction, the hardness of the magnesium metal has also been increased. As Figure 4 shown, the corrosion rate of the metal added with nanoparticles has not increased significantly. The corrosion rate is 3.82 μg / mm after 14 days 2 , slightly lower than that of the metal added with 2.3% nanoparticles, mainly because the content of the added nanoparticles is relatively high, affecting its degradation ability. As Figure 5The cell viability of magnesium metal with about 4.1% by mass fraction of activated tungsten carbide added is 94%. This is mainly because the environment in the cell culture medium is more suitable for cell growth, thus promoting cell proliferation and enhancing the bioactivity of the material.

[0062] Example 3

[0063] Preparation of activated tungsten carbide / titanium carbide nanoparticle magnesium metal composite:

[0064] 1) Weigh the magnesium metal raw material and carbide raw material respectively. The metal raw material includes pure magnesium (purity 99.95%). In this example, the composition used is a magnesium ingot with a mass fraction of about 95%, and a mixture of tungsten carbide / titanium carbide nanoparticles with a mass fraction of about 5% and a diameter of about 100 nm. The mass ratio of tungsten carbide to titanium carbide in the mixture is 1:1.

[0065] 2) Put the tungsten carbide / titanium carbide nanoparticles into a glass petri dish filled with deionized water. The volume ratio of the solution to the added carbide is 3:1. Then, select a laser with a wavelength of 1064 nm and a power of 50 W, use a galvanometer to control, with a linear velocity of 1.0 mm / s, a line spacing of 0.1 mm, and an irradiation time of 3 h. Then take out the activated carbide and perform vacuum drying treatment at 300 °C for 12 h.

[0066] 3) Uniformly mix the mixture of tungsten carbide and titanium carbide and potassium hexafluoroaluminate with a mass fraction of 0.1% of the mass of the carbide nanoparticles to obtain a mixture. The powder mixture is mixed by a mechanical shaker at about 400 rpm for about 50 min.

[0067] 4) Under the protection of an inert gas, melt the high-purity magnesium ingot in a graphite crucible at 800 °C. Then add potassium hexafluoroaluminate (KAlF4) and the mixture of tungsten carbide and titanium carbide. The molten potassium hexafluoroaluminate (KAlF4) is used to assist the incorporation of tungsten carbide and titanium carbide, and then it is introduced into the molten magnesium through mechanical stirring;

[0068] 5) Add a mixture of sodium chloride and potassium chloride with a ratio of 1:1, with an addition content of 1% of the volume of the added pure magnesium material to protect the magnesium alloy melt from oxidation. Then continue stirring for 2 h and pour the melt into a mold to cool.

[0069] 6) Perform rolling treatment on the cast magnesium metal composite at a temperature of 350 °C. The rolling sample is taken perpendicular to the casting mold wall. The rolling pressure is 15 KN, the rolling speed is 5 mm / min, and the rolling deformation is 80%. Finally, an activated carbide nanoparticle-reinforced magnesium metal composite is obtained.

[0070] 7) Cut the cast material to make samples of suitable size for subsequent mechanical, compositional, and biocompatibility tests. After testing, the results all show that the method of Example 3 achieved the expected benefits, that is, the nanoparticles were effectively and uniformly dispersed in the magnesium matrix, and effectively reduced the grain size, improved the mechanical strength of the material, and enabled the prepared composite material to maintain a good degradation rate of the magnesium alloy without having a negative impact on its biocompatibility.

[0071] Example 4

[0072] Preparation of activated tungsten carbide / titanium carbide / silicon carbide nanomagnesium metal composite:

[0073] 1) Weigh the magnesium metal raw material and carbide raw materials respectively. The metal raw material includes pure magnesium (purity of 99.95%). The composition used in this example is about 95% by mass of pure magnesium ingots and about 5% by mass of a mixture of tungsten carbide / titanium carbide / silicon carbide nanoparticles with a diameter of about 50 nm. The ratio of the three carbides is 3:1:2

[0074] 2) Place the tungsten carbide / titanium carbide / silicon carbide nanoparticles in a glass petri dish containing deionized water. The volume ratio of the solution to the added carbide is 3:1. Then select a laser with a wavelength of 1064 nm and a power of 60 W, use galvanometer control, a linear velocity of 1.5 mm / s, a line spacing of 0.2 mm, and an irradiation time of 3 h. Then take out the activated carbide and perform vacuum drying treatment at 300 °C for 24 h.

[0075] 3) Uniformly mix the mixture of tungsten carbide / titanium carbide / silicon carbide and potassium hexafluoroaluminate (KAlF4) accounting for 0.1% of the mass of the carbide nanoparticles to obtain a mixture. The powder mixture is mixed by a mechanical shaker at about 500 rpm for about 30 min.

[0076] 4) Under the protection of an inert gas, melt the high-purity magnesium ingot in a graphite crucible at 750 °C. Then add potassium hexafluoroaluminate (KAlF4) and the mixture of tungsten carbide / titanium carbide / silicon carbide. The molten potassium hexafluoroaluminate (KAlF4) is used to assist the incorporation of tungsten carbide / titanium carbide / silicon carbide, and then it enters the molten magnesium through mechanical stirring;

[0077] 5) Add a mixture of sodium chloride and potassium chloride in a ratio of 1:1, with an addition content of 1.3% of the volume of the added pure magnesium material to protect the magnesium alloy melt from oxidation. Then continue stirring for 1.5 h, and then pour the melt into a mold.

[0078] 6) Cut the as-cast metal and make samples of suitable sizes for subsequent mechanical, compositional, and biocompatibility tests. After testing, the results all show that the method of Example 4 achieved the expected benefits, that is, the nanoparticles were effectively and uniformly dispersed in the magnesium matrix, and effectively reduced the grain size, improved the mechanical strength of the material, and enabled the prepared composite material to maintain a good degradation rate of the magnesium alloy without having a negative impact on its biocompatibility.

[0079] Example 5

[0080] The testing means used in this example are the same as those in Example 1.

[0081] The differences between this example and Example 1 are in Step 1 and Step 4. In Step 1, pure magnesium, magnesium-calcium master alloy raw materials, and carbide raw materials are weighed respectively. The ratio of pure magnesium to the magnesium-calcium master alloy is 1:1. The content of magnesium element in the magnesium-calcium alloy accounts for 98%, and the content of calcium element accounts for 2%. In Step 4, before casting into the steel mold, an appropriate amount of magnesium master alloy (weight ratio of 1:1) is added to the crucible, and then the uniformly mixed melt is poured into the mold and cooled. The subsequent processes are the same as those in Example 1. After testing, the results all show that the method of Example 5 achieved the expected benefits, that is, the nanoparticles were effectively and uniformly dispersed in the magnesium matrix, and effectively reduced the grain size, improved the mechanical strength of the material, and enabled the prepared composite material to maintain a good degradation rate of the magnesium alloy without having a negative impact on its biocompatibility.

[0082] Example 6

[0083] The testing means used in this example are the same as those in Example 1.

[0084] The differences between this example and Example 1 are in Step 1 and Step 4. In Step 1, pure magnesium, magnesium-lithium master alloy raw materials, and carbide raw materials are weighed respectively. The ratio of pure magnesium to the magnesium-lithium master alloy is 1:1. The content of magnesium element in the magnesium-lithium alloy accounts for 98%, and the content of lithium element accounts for 2%. In Step 4, before casting into the steel mold, an appropriate amount of magnesium-lithium master alloy (weight ratio of 1:1) is added to the crucible, and then the uniformly mixed melt is poured into the mold and cooled. The subsequent processes are the same as those in Example 1. After testing, the results all show that the method of Example 6 achieved the expected benefits, that is, the nanoparticles were effectively and uniformly dispersed in the magnesium matrix, and effectively reduced the grain size, improved the mechanical strength of the material, and enabled the prepared composite material to maintain a good degradation rate of the magnesium alloy without having a negative impact on its biocompatibility.

[0085] Example 7

[0086] The testing means used in this example are the same as those in Example 1.

[0087] The differences between this embodiment and Embodiment 1 are Steps 1 and 4. In Step 1, pure magnesium, magnesium-zirconium-rare earth master alloy raw materials and carbide raw materials are weighed respectively. The ratio of pure magnesium to magnesium-lithium master alloy is 1:1. In the magnesium-zirconium-rare earth alloy, the content ratio of magnesium element is 85.0%, the content ratio of yttrium element is 8.0%, the content ratio of zirconium element is 1.0%, and the content ratio of rare earth elements is 6.0%. In Step 4, before casting into the steel mold, an appropriate amount of magnesium-zirconium-rare earth master alloy raw materials (weight ratio of 1:1) is added to the crucible, and then the uniformly mixed melt is poured into the mold for cooling. The subsequent processes are the same as those in Embodiment 1. After testing, the results all show that the method of Embodiment 7 achieves the expected benefits, that is, the nanoparticles are effectively and uniformly dispersed in the magnesium matrix, and effectively reduce the grain size, improve the mechanical strength of the material, and enable the prepared composite material to maintain a good degradation rate of the magnesium alloy without having a negative impact on its biocompatibility.

[0088] As can be seen from the above embodiments, in the casting process of the present invention, activated carbide nanoparticles with a fraction of about 1.8% to 10% of the magnesium alloy and a diameter of 10 to 500 nm are added. The carbide nanoparticles used are activated by laser in the solution so that they can be uniformly distributed in the magnesium metal solution, and the uniformly distributed carbide nanoparticles are evenly distributed between the grains of the magnesium alloy, hindering the growth of grains and achieving the purpose of improving the strength.

[0089] The composite magnesium alloy is composed of activated carbide nanoparticles and a magnesium matrix: The microstructure of the activated carbide nanoparticles is nanoparticles with a diameter ranging from 10 to 500 nm, and the mass fraction of the activated carbide nanoparticles in the composite material is about 1.8% to 10%. The carbide nanoparticles are activated before use, that is, immersed in a glass petri dish filled with deionized water, and the volume ratio of the aqueous solution to the added carbide is 2:1 - 5:1. Then, a laser with a wavelength of 1064 nm, a power of 40 - 80 W, a linear velocity of 0.01 mm / s - 10 mm / s, a line spacing of 0.05 - 1 mm, and an irradiation time of 1 - 3 h is selected. Then, the activated carbide is taken out and dried at 150 - 300 °C for 8 - 24 h. The activated carbide nanoparticles are not prone to agglomeration during the magnesium metal casting process and are evenly dispersed in the magnesium matrix, which hinders the growth of magnesium grains and improves the mechanical strength. The unactivated nanoparticles are difficult to be effectively and evenly dispersed and are prone to agglomeration, which is not conducive to improving the material strength and detecting the in-vivo degradation situation. In the present invention, the diameter of the nanoparticles is about 10 to 500 nm, and the mass fraction is 1.8% to 10%. Nanoparticles that are too large or too small cannot achieve good effects. The presence of too large nanoparticles will affect the mechanical properties of the composite material manufactured by the present invention, while too small a diameter will affect the degradation behavior of magnesium metal. A mass fraction lower than 1.8% cannot effectively change the mechanical properties of the composite material of the present invention, and a mass fraction higher than 10% will affect the dispersion of nanoparticles in the magnesium matrix and reduce the mechanical properties of the material. The entire process adopts the method of stirring casting of metallic magnesium. Since the carbide nanoparticles have undergone laser activation treatment, the mechanical stirring can promote the uniform dispersion of the nanoparticles in the molten metal, enabling the magnesium composite material to maintain good mechanical strength and a stable degradation rate. Since the carbide itself has high fracture toughness, high strength, high temperature resistance, and low wear properties, it can also improve the relevant properties of the magnesium alloy. And the dispersed carbide nanoparticles are non-magnetic, which enables magnetic resonance imaging examination of the soft tissues near the implant made of carbide without artifacts.

[0090] The above is only the preferred implementation method of the present invention. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

[0091] Matters not covered by the present invention are well-known technologies.

Claims

1. An activated carbide nanoparticle-reinforced magnesium metal composite material, characterized in that the composite material comprises a magnesium metal matrix and activated carbide nanoparticles distributed in the grain gaps of the magnesium matrix; the mass fraction of the nanoparticles in the material is 1.8% to 10%; The magnesium metal is pure magnesium or magnesium alloy MgM, where M includes one or more of zinc, calcium, aluminum, silver, copper, lithium, zirconium, strontium, yttrium, gadolinium, niobium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, and scandium; The nanoparticles have a diameter of 10 to 500 nm; In the magnesium alloy MgM, the mass percentage content of M is 0.1% - 3%; The carbide nanoparticles are one or more of metal carbides and non-metal carbides; The carbide nanoparticles are subjected to laser surface activation treatment, and the operation is as follows: Immerse the nanoparticles in deionized water, then select a laser with a wavelength of 1064 nm, a power of 40 - 80 W, a linear velocity of 0.01 mm / s - 10 mm / s, a line spacing of 0.05 - 1 mm, and an irradiation time of 0.5 - 5 h. Then take out the activated carbide and dry it at 150 - 300 °C for 8 - 24 h; among them, The volume ratio of deionized water to carbide particles is 2:1 - 5:1; The preparation method of the activated carbide nanoparticle-reinforced magnesium metal composite material includes the following preparation steps: (1) Weigh pure magnesium and carbide raw materials respectively according to the designed ratio; (2) Mix potassium hexafluoroaluminate (KAlF4) with the nanoparticles; where potassium hexafluoroaluminate accounts for 0.01% - 0.1% of the mass fraction of the carbide nanoparticles; (3) Under the protection of an inert gas, first melt the pure magnesium ingot in a graphite crucible at 500 - 1000 °C; then add the mixture of potassium hexafluoroaluminate (KAlF4) and the nanoparticles, and then introduce them into the molten magnesium through mechanical stirring for 0.5 - 3 h; (4) Cover the surface of the molten magnesium after adding the nanoparticles with a mixture of sodium chloride and potassium chloride, then continue stirring for 1 - 2 h, and then pour the melt into a mold and cool to obtain a magnesium metal composite material; When the magnesium metal is a magnesium alloy, the following steps are also required: Add MgM or intermediate metal M to the melt, at this time the melting temperature is 500 - 1000 °C, mechanically stir for 0.5 - 3 h, and then pour the melt into a mold for cooling to obtain a composite metal; (5) Roll the cast magnesium metal composite material at a temperature of 250 - 500 °C, the rolling pressure is 1 KN - 10 KN, the rolling speed is 0.1 - 10 mm / min, and the rolling deformation is 75 - 90%, and finally obtain the activated carbide nanoparticle-reinforced magnesium metal composite material.

2. The activated carbide nanoparticle-reinforced magnesium metal composite material according to claim 1, characterized in that the nanoparticles are one or more of tungsten carbide, titanium carbide, niobium carbide, chromium carbide, nickel carbide, vanadium carbide, zirconium carbide, silicon carbide, and boron carbide.

3. The activated carbide nanoparticle-reinforced magnesium metal composite material according to claim 1, characterized in that, The inert gas in the preparation method is a mixed gas protected by 99% argon and 1% sulfur hexafluoride gas.

4. The preparation method of the activated carbide nanoparticle-reinforced magnesium metal composite material according to claim 1, characterized in that In preparation method step (4), the mass ratio of sodium chloride to potassium chloride is 1:1, and the addition amount of the mixture accounts for 0.2% - 2% of the volume of the molten magnesium metal.

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