A functional coating on the surface of an active metal material and a precise preparation method thereof for additive and subtractive materials

Abstract

The present invention provides a functional coating on the surface of an active metal material and a precise preparation method for additive and subtractive materials thereof, the preparation method comprising the following steps: S1. selecting micron powder with a particle size of 20 to 75 μm and nanoparticles with a particle size of 10 to 500 nm, uniformly mixing them, vacuum drying them, and setting them aside; S2. using an ultrafast laser to process a microstructure on the surface of a substrate; the ultrafast laser power is 10 to 60 W, the pulse frequency is 5 to 50 kHz, and the walking speed is 100 to 500 cm / s; S3. spreading the mixed powder obtained in S1 on the surface of the substrate obtained in S2, uniformly paving it in a manner of filling the microstructure, and using an SLM continuous laser for forming; the SLM continuous laser power is 50 to 150 W, the scanning speed is 100 to 800 mm / s, and the scanning spacing is 0.03 to 0.05 mm; S4. repeating the aforementioned steps S2 and S3 until the desired coating thickness is reached, thereby obtaining the functional coating on the surface of the active metal material. This preparation method can significantly improve the wear resistance and corrosion resistance of active metal surfaces, while helping them express functionalities such as antibacterial properties, meeting their application needs in high-end medical and other fields.

Description

Technical Field

[0001] The present invention relates to the technical field of metal material preparation, and in particular to a method for accurately preparing a functional coating on the surface of an active metal material and an additive and subtractive coating. Background Art

[0002] Active metals, such as titanium alloys, magnesium alloys and zinc alloys, are widely used in medical devices and other fields due to their low density, high strength and good biological properties. However, the corrosion resistance of active metal surfaces is poor. After being corroded, the mechanical properties will drop sharply, and fractures will occur at any corrosion point, causing device failure. At the same time, bone implants made of traditional active metals will have infection problems after surgery, or cause inflammation due to surface wear and peeling of corrosion products, which in turn affects human health and greatly limits the application of traditional active metal materials. Therefore, there is an urgent need to design and prepare wear-resistant, corrosion-resistant and antibacterial functional coatings for the surfaces of traditional active metal materials. Existing surface treatment technologies, such as chemical plating, electroplating and thermal spraying, can improve the surface properties of active metals to a certain extent, but in actual applications, there are still problems such as insufficient coating adhesion, uneven thickness and high porosity, which limit the preparation effect and use efficacy of active metal surface coatings. Therefore, it is urgent to design and develop new magnesium alloy protective coating preparation technologies.

[0003] Laser Additive Manufacturing (LAM), as an emerging material preparation method, can rapidly form a coating of a certain thickness on the surface of a part by cumulatively adding layers one by one. This ensures that the interface is metallurgically bonded while giving the surface the special properties required for the application. Based on this, in order to meet the target performance required by the part, researchers often mechanically mix some nano- or micro-ceramic particles with metal powders, and then deposit them layer by layer through LAM to achieve the specific needs of the metal parts in the target occasion. This method often includes powder-feeding additive methods, namely laser cladding (LC), and powder-spreading additive methods, namely selective laser melting (SLM).

[0004] Although the Chinese invention patent application with publication number CN110729391A, "Method, device and thermoelectric material block for preparing magnesium silicide thermoelectric material block", uses magnesium silicide and pure magnesium powder as LAM powder raw materials, adopts powder feeding additive method, namely LC process, to directly form magnesium silicide thermoelectric material block with thermoelectric performance, but because it adopts mechanical powder mixing method, the size and distribution of the phase inside the prepared parts cannot be strictly controlled; the Chinese invention patent application with publication number CN115041678A, "A kind of micro-nanostructured high-activity spherical aluminum alloy and its preparation method and application" and Chinese invention patent application with publication number CN115156525A, "An active modified spherical magnesium alloy powder based on electrostatic self-assembly, its preparation method and application", propose a method of first nano-modifying the surface of micron powder and then performing LAM forming. However, in actual operation, the nanoparticles modified on the surface of micron powder cannot be accurately quantified, and it is even more impossible to achieve accurate distribution within the formed part after LAM forming. The various phases formed in situ will also be randomly distributed under the drive of Marangoni force. Therefore, how to accurately and quantitatively control the precise forming and controllable distribution of different types of phases in the final part is one of the key issues that need to be solved at this stage. It is also a technical difficulty that restricts the effective performance of the designed material.

[0005] Ultrafast laser micro-nanomachining (ULM) is a novel subtractive technology that uses high-energy pulsed ablation to precisely cut surfaces such as titanium and magnesium alloys. Currently, it is commonly used in SLM to remove residual powder from sidewalls. Leveraging ULM and the layer-by-layer deposition capabilities of SLM technology, ULM can precisely deposit multifunctional coatings on active metal surfaces. Translating the coating's multifunctional design into precise shaping from a fabrication perspective is a critical challenge currently underway.

[0006] The Chinese invention patent application with publication number CN118371729A, "A method for additive and subtractive composite molding of an amorphous alloy," discloses a method for obtaining an amorphous alloy through ultrafast laser micro-nano processing and SLM, so that the amorphous alloy powder is connected to the amorphous alloy substrate in a bonding manner, and the new printed layer has a better fusion effect with the previous layer, thereby reducing the formation of internal defects and effectively improving the internal effect of the amorphous alloy. However, this method improves the alloy performance by reducing the formation of internal defects, and does not enhance the performance of active metals. The wear and corrosion resistance still needs to be further improved, and the amorphous alloy does not have biological activity and cannot meet the application needs in the medical field.

[0007] Therefore, it is of great significance to develop a functional coating on the surface of active metal materials with excellent wear resistance and corrosion resistance, which is suitable for application requirements in the medical field and a preparation method thereof. Summary of the Invention

[0008] In view of the fact that the existing alloy material additive and subtractive composite forming methods have the problems that the wear resistance and corrosion resistance still need to be further improved, and they do not have biological activity and cannot meet the application requirements in the medical field, the present invention provides a functional coating on the surface of active metal materials and a preparation method thereof. While significantly improving the surface wear resistance and corrosion resistance of active metals such as titanium, magnesium, and zinc alloys, it can help them achieve functional expression such as antibacterial properties, meet their application needs in high-end medical fields and other fields, and provide new possibilities for the application expansion of active metals in various fields.

[0009] To achieve the above object, the technical solution adopted by the present invention is:

[0010] A method for accurately preparing a functional coating on the surface of an active metal material by additive and subtractive methods comprises the following steps:

[0011] S1. Select micron powder with a particle size of 20 to 75 μm and nanoparticles with a particle size of 10 to 500 nm, mix them evenly, vacuum dry them, and set aside;

[0012] S2. Using an ultrafast laser to process microstructures on the substrate surface; the ultrafast laser power is 10 to 60 W, the pulse frequency is 5 to 50 kHz, and the travel speed is 100 to 500 cm / s;

[0013] S3. The mixed powder obtained in S1 is laid on the surface of the substrate obtained in S2, and is evenly tiled in a manner to fill the microstructure, and formed using a SLM continuous laser; the SLM continuous laser power is 50 to 150 W, the scanning speed is 100 to 800 mm / s, and the scanning pitch is 0.03 to 0.05 mm;

[0014] S4. Repeat the above steps S2 and S3 until the desired coating thickness is reached, thereby obtaining the functional coating on the surface of the active metal material.

[0015] Furthermore, the ratio of the micron powder and the nanoparticles in S1 is (80-95):(5-20).

[0016] Furthermore, the sphericity of the micron powder in S1 is ≥85%.

[0017] Furthermore, the uniform mixing in S1 is performed by planetary ball milling; the planetary ball milling mixing time is 0.5 to 1.5 hours, the rotation speed is 100 to 300 r / min, and the ball-to-material mass ratio is (1 to 5):1.

[0018] Furthermore, in addition to filling 1 / 2 to 1 / 3 of the tank volume with anhydrous ethanol (purity 99.9%) as a liquid medium, the remaining tank volume is filled with high-purity argon gas to avoid problems such as oxidation and powder adhesion during the ball milling process.

[0019] Furthermore, the vacuum drying temperature in S1 is 100 to 200° C., and the pressure is -0.08 to -0.1 MPa.

[0020] Furthermore, the ultrafast laser in S2 is a femtosecond laser and / or a picosecond laser.

[0021] Furthermore, the ultrafast laser described in S2 is a femtosecond laser. Because the heat-affected zone after femtosecond laser processing is extremely small, there are no fine cracks, the surface physical properties change little, and the processed holes are deep pit-shaped, nanoparticles can be shaken in well and are not easily pulled out during multiple powder coatings.

[0022] Furthermore, the substrate in S2 is an active metal substrate; the active metal is one or more of titanium-based materials, magnesium-based materials, iron-based materials, and zinc-based materials.

[0023] Furthermore, the substrate is a conventionally prepared substrate, and its surface needs to be ground, polished and cleaned with alcohol until it reaches a mirror surface.

[0024] Furthermore, if the substrate is an SLM substrate directly formed in the device, an ultrafast laser is used to quickly scan its surface; the ultrafast laser power is 10 to 40 W, the pulse frequency is 5 to 50 kHz, the travel speed is 600 to 1000 cm / s, and the overlap rate is 10 to 70%.

[0025] Furthermore, the microstructure described in S2 is a dot matrix hole groove, the hole diameter is 3 to 20 μm, the depth is 1 to 5 μm, and the minimum distance between two holes is 1 hole diameter.

[0026] Furthermore, the step of spreading the mixed powder on the substrate surface in step S3 is to repeatedly spread the mixed powder using a scraper to ensure that the nanoparticles can completely fall into and fill the deep pits ablated by the ultrafast laser, and at the same time, the micron powder can be evenly spread on the surface.

[0027] Furthermore, the scraper is a ceramic scraper, which can ensure that the nanoparticles that fall into the micro-pits will not be dragged out due to electrostatic force during the repeated spreading of the powder. At the same time, the sharp ceramic scraper can effectively scrape off the nanoparticles attached to the micron powder.

[0028] Furthermore, after the SLM continuous laser forming is performed in S3, the step of using an ultrafast laser to perform full-width rapid scanning is also included.

[0029] Furthermore, the ultrafast laser power is 10-40W, the pulse frequency is 5-50kHz, the travel speed is 600-1000cm / s, and the overlap rate is 10-70%.

[0030] Another object of the present invention is to provide a functional coating on the surface of an active metal material.

[0031] A functional coating on the surface of an active metal material is prepared by any of the preparation methods described above.

[0032] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0033] The functional coating on the surface of the active metal material of the present invention is prepared by alternating between ultrafast laser point-by-point subtraction and SLM technologies. A microstructure is first prepared on the target substrate to store the nano-reinforced particles shaken off during powder spreading, and then the nano-particles are precisely deposited to strengthen the target coating through SLM technology. The enrichment position of the nano-particles is precisely controlled by mechanical regulation to achieve precise regulation of the coating phase, the spatial position and distribution of the nano-particles, so that the functional nano-particles can be released in a controllable manner according to the design concept. While significantly improving the wear resistance and corrosion resistance of the active metal surface, it can help it achieve functional expression such as antibacterial properties, meeting its application needs in high-end medical and other fields.

[0034] The method for preparing functional coatings on the surface of active metal materials of the present invention can directly deposit a protective layer on the surface of alloy parts formed by SLM, or the surface of the alloy block to be protected can be polished and then the coating can be prepared by this method. It is convenient, fast, simple, efficient and can be used flexibly. The prepared coating has few defects such as pores and cracks, and the grains are extremely fine, mainly dense equiaxed crystal structure, and are metallurgically bonded to the matrix. The added nanoparticles not only act as in-situ nucleating agents to promote grain refinement and dispersion strengthening, but also, due to the precise distribution of nanoparticles within the coating, a reliable method can be provided for the controllable degradation and biological function expression of the coating. While achieving the improvement of mechanical effects such as particle enhancement and in-situ strengthening, the controlled release of functional nanoparticles is also achieved. The resulting coating can achieve controllable thickness and metallurgical bonding. The nanoparticles are precisely distributed within the coating according to the designer's ideas, and the required coating efficacy can be expressed in sequence according to the designer's ideas. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The invention is further described with reference to the accompanying drawings, but the embodiments in the accompanying drawings do not constitute any limitation to the invention. A person skilled in the art can obtain other drawings based on the following drawings without making any creative effort.

[0036] Figure 1 This is a flow chart for preparing the functional coating on the surface of the active metal material of the present invention.

[0037] Figure 2 This is a microstructure diagram of the functional coating on the surface of the active metal material in Example 1 of the present invention.

[0038] Figure 31 is a SEM image of the active metal surface coating of Comparative Example 1 of the present invention.

[0039] Figure 4 1 is a SEM image of the active metal surface coating of Comparative Example 2 of the present invention.

[0040] Figure 5 This is a microscopic morphology of the active metal surface coating of Comparative Example 3 of the present invention.

[0041] Figure 6 This is a microscopic morphology of the active metal surface coating of Comparative Example 4 of the present invention.

[0042] Figure 7 This is a microscopic morphology of the active metal surface coating of Comparative Example 5 of the present invention.

[0043] Figure 8 These are macroscopic and microscopic morphologies of the active metal surface coating of Comparative Example 6 of the present invention.

[0044] Figure 9 It is the cell staining image of Example 1 of the present invention and the AZ91D sample formed by SLM.

[0045] Figure 10 2 is an antibacterial effect diagram of Example 1 of the present invention and Comparative Example 7. DETAILED DESCRIPTION

[0046] To better illustrate the objectives, technical solutions, and advantages of the present invention, the present invention is further described by the following examples. Obviously, the following examples are only a part of the embodiments of the present invention, rather than all the embodiments; it should be understood that the embodiments of the present invention are only used to illustrate the technical effects of the present invention, and are not used to limit the scope of protection of the present invention.

[0047] The raw materials in the examples can be obtained commercially; unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0048] Example 1

[0049] A method for accurately preparing a functional coating on the surface of an active metal material by additive and subtractive methods comprises the following steps:

[0050] S1. Weigh nanoparticles with a purity of ≥99.90wt.% and micron powder for SLM as raw materials by weight percentage, select 90wt.% AZ91D magnesium alloy micron powder with a particle size of 50μm and 10wt.% ZnO nanoparticles with a particle size of 100nm, put them into a planetary ball mill for mixing, the mixing time is selected as 1 hour, the speed is 150r / min, the ball-to-material mass ratio is 2:1, the spherical tank is filled with 1 / 2 volume of anhydrous ethanol (purity ≥99vol.%) and 1 / 2 volume of high-purity argon (purity ≥99.999vol.%), the mixed target powder is placed in a vacuum drying oven for high temperature and vacuum drying, the drying temperature is set to 150℃, the vacuum pressure is set to -0.1MPa, the heating rate is 80℃ / min, the holding time is 1h, and then the temperature is reduced to 25℃ for storage. The obtained powder material is placed in a vacuum bag and vacuumed for storage for standby use;

[0051] S2. AZ91D magnesium alloy was first formed using the SLM method. The entire substrate surface was then de-powdered using an ultrafast laser. The ultrafast laser had a power of 20W, a pulse frequency of 10kHz, a travel speed of 800cm / s, and an overlap ratio of 50%. A femtosecond laser was used to machine dot-matrix holes on the surface of the AZ91D magnesium alloy substrate. The holes had a diameter of 10μm and a depth of 3μm, with a minimum spacing of one hole diameter between two holes. The femtosecond laser had a power of 30W, a pulse frequency of 20kHz, and a travel speed of 200cm / s.

[0052] S3. The mixed powder obtained in S1 is spread on the surface of the substrate obtained in S2, and is evenly spread in a manner of filling the microstructure. A ceramic scraper is used to repeatedly spread the mixed powder to ensure that the nanoparticles can completely fall into and fill the deep pits ablated by the ultrafast laser. At the same time, the micron powder can also be evenly spread on the surface of the substrate to be protected. The thickness of each layer of powder is set at 40μm. SLM continuous laser is used for forming, and the scanning strategy is selected as a zigzag scanning mode; the SLM continuous laser power is 100W, the scanning speed is 500mm / s, and the scanning spacing is 0.04mm; an ultrafast laser is used for full-width rapid scanning to smooth the SLM surface. The ultrafast laser power is 20W, the pulse frequency is 10kHz, the walking speed is 800cm / s, and the overlap rate is 50%;

[0053] S4. Repeat the above steps S2 and S3 until the desired coating thickness is reached, thereby obtaining the functional coating on the surface of the active metal material.

[0054] Example 2

[0055] A method for accurately preparing a functional coating on the surface of an active metal material by additive and subtractive methods comprises the following steps:

[0056] S1. Weigh nanoparticles with a purity of ≥99.90wt.% and micron powder for SLM as raw materials by weight percentage, select 90wt.% AZ91D magnesium alloy micron powder with a particle size of 40μm and 10wt.% ZnO nanoparticles with a particle size of 200nm, put them into a planetary ball mill for mixing, the mixing time is selected as 1 hour, the speed is 150r / min, the ball-to-material mass ratio is 2:1, the spherical tank is filled with 1 / 2 volume of anhydrous ethanol (purity ≥99vol.%) and 1 / 2 volume of high-purity argon (purity ≥99.999vol.%), the mixed target powder is placed in a vacuum drying oven for high temperature and vacuum drying, the drying temperature is set to 150℃, the vacuum pressure is set to -0.1MPa, the heating rate is 80℃ / min, the holding time is 1h, and then the temperature is reduced to 25℃ for storage. The obtained powder material is placed in a vacuum bag and vacuumed for storage for standby use;

[0057] S2. A cast AZ91D magnesium alloy substrate was directly polished to a mirror finish and placed in an SLM chamber. A femtosecond laser was used to machine dot-matrix holes on the surface of the AZ91D magnesium alloy substrate. The holes had a diameter of 10 μm and a depth of 3 μm, with a minimum spacing of one hole diameter between two holes. The femtosecond laser had a power of 20 W, a pulse frequency of 10 kHz, and a travel speed of 500 cm / s.

[0058] S3. The mixed powder obtained in S1 is spread on the surface of the substrate obtained in S2, and is evenly spread in a manner of filling the microstructure. A ceramic scraper is used to repeatedly spread the mixed powder to ensure that the nanoparticles can completely fall into and fill the deep pits ablated by the ultrafast laser. At the same time, the micron powder can also be evenly spread on the surface of the substrate to be protected. The thickness of each layer of powder is set at 40μm. SLM continuous laser is used for forming, and the scanning strategy is selected as a zigzag scanning mode; the SLM continuous laser power is 80W, the scanning speed is 600mm / s, and the scanning spacing is 0.045mm; an ultrafast laser is used for full-width rapid scanning to smooth the SLM surface. The ultrafast laser power is 10W, the pulse frequency is 20kHz, the walking speed is 600cm / s, and the overlap rate is 60%;

[0059] S4. Repeat the above steps S2 and S3 until the desired coating thickness is reached, thereby obtaining the functional coating on the surface of the active metal material.

[0060] Example 3

[0061] A method for accurately preparing a functional coating on the surface of an active metal material by additive and subtractive methods comprises the following steps:

[0062] S1. Weigh nanoparticles with a purity of ≥99.90wt.% and micron powder for SLM as raw materials by weight percentage, select 85wt.% WE43 magnesium powder with a particle size of 40μm and 15wt.% CuO nanoparticles with a particle size of 200nm, put them into a planetary ball mill for mixing, the mixing time is selected as 1 hour, the speed is 150r / min, the ball-to-material mass ratio is 2:1, the spherical tank is filled with 1 / 2 volume of anhydrous ethanol (purity ≥99vol.%) and 1 / 2 volume of high-purity argon (purity ≥99.999vol.%), the mixed target powder is placed in a vacuum drying oven for high temperature and vacuum drying, the drying temperature is set to 150℃, the vacuum pressure is set to -0.1MPa, the heating rate is 80℃ / min, the holding time is 1h, and then the temperature is reduced to 25℃ for storage. The obtained powder material is placed in a vacuum bag and vacuumed for storage for standby use;

[0063] S2. AZ91D magnesium alloy was first formed using the SLM method. The entire substrate was then subjected to surface powder removal using an ultrafast laser. The ultrafast laser had a power of 20W, a pulse frequency of 10kHz, a travel speed of 800cm / s, and an overlap ratio of 50%. A femtosecond laser was used to machine dot-matrix holes on the surface of the AZ91D magnesium alloy substrate. The holes had a diameter of 15μm and a depth of 4μm, with a minimum spacing of one hole diameter between two holes. The femtosecond laser had a power of 30W, a pulse frequency of 20kHz, and a travel speed of 200cm / s.

[0064] S3. The mixed powder obtained in S1 is spread on the surface of the substrate obtained in S2, and is evenly spread in a manner of filling the microstructure. A ceramic scraper is used to repeatedly spread the mixed powder to ensure that the nanoparticles can completely fall into and fill the deep pits ablated by the ultrafast laser. At the same time, the micron powder can also be evenly spread on the surface of the substrate to be protected. The thickness of each layer of powder is set at 40μm. SLM continuous laser is used for forming, and the scanning strategy is selected as a zigzag scanning mode; the SLM continuous laser power is 100W, the scanning speed is 500mm / s, and the scanning spacing is 0.04mm; an ultrafast laser is used for full-width rapid scanning to smooth the SLM surface. The ultrafast laser power is 20W, the pulse frequency is 10kHz, the walking speed is 800cm / s, and the overlap rate is 50%;

[0065] S4. Repeat the above steps S2 and S3 until the desired coating thickness is reached, thereby obtaining the functional coating on the surface of the active metal material.

[0066] Example 4

[0067] A method for accurately preparing a functional coating on the surface of an active metal material by additive and subtractive methods comprises the following steps:

[0068] S1. Weigh nanoparticles with a purity of ≥99.90wt.% and micron powder for SLM as raw materials by weight percentage, select 85wt.% WE43 magnesium powder with a particle size of 40μm and 15wt.% CuO nanoparticles with a particle size of 200nm, put them into a planetary ball mill for mixing, the mixing time is selected as 1 hour, the speed is 150r / min, the ball-to-material mass ratio is 2:1, the spherical tank is filled with 1 / 2 volume of anhydrous ethanol (purity ≥99vol.%) and 1 / 2 volume of high-purity argon (purity ≥99.999vol.%), the mixed target powder is placed in a vacuum drying oven for high temperature and vacuum drying, the drying temperature is set to 150℃, the vacuum pressure is set to -0.1MPa, the heating rate is 80℃ / min, the holding time is 1h, and then the temperature is reduced to 25℃ for storage. The obtained powder material is placed in a vacuum bag and vacuumed for storage for standby use;

[0069] S2. A cast AZ91D magnesium alloy substrate was directly polished to a mirror finish and placed in an SLM chamber. A femtosecond laser was used to machine dot-matrix holes on the surface of the AZ91D magnesium alloy substrate. The holes had a diameter of 8 μm and a depth of 2 μm, with a minimum spacing of one hole diameter between two holes. The femtosecond laser had a power of 20 W, a pulse frequency of 10 kHz, and a travel speed of 500 cm / s.

[0070] S3. The mixed powder obtained in S1 is spread on the surface of the substrate obtained in S2, and is evenly spread in a manner of filling the microstructure. A ceramic scraper is used to repeatedly spread the mixed powder to ensure that the nanoparticles can completely fall into and fill the deep pits ablated by the ultrafast laser. At the same time, the micron powder can also be evenly spread on the surface of the substrate to be protected. The thickness of each layer of powder is set at 40μm. SLM continuous laser is used for forming, and the scanning strategy is selected as a zigzag scanning mode; the SLM continuous laser power is 80W, the scanning speed is 600mm / s, and the scanning spacing is 0.045mm; an ultrafast laser is used for full-width rapid scanning to smooth the SLM surface. The ultrafast laser power is 10W, the pulse frequency is 20kHz, the walking speed is 600cm / s, and the overlap rate is 60%;

[0071] S4. Repeat the above steps S2 and S3 until the desired coating thickness is reached, thereby obtaining the functional coating on the surface of the active metal material.

[0072] Comparative Example 1

[0073] A method for the precise additive and subtractive preparation of active metal surface coatings, comprising the following steps:

[0074] S1. Weigh nanoparticles with a purity of ≥99.90wt.% and micron powder for SLM as raw materials by weight percentage, select 85wt.% WE43 magnesium powder with a particle size of 40μm and 15wt.% CuO nanoparticles with a particle size of 200nm, put them into a planetary ball mill for mixing, the mixing time is selected as 1 hour, the speed is 150r / min, the ball-to-material mass ratio is 2:1, the spherical tank is filled with 1 / 2 volume of anhydrous ethanol (purity ≥99vol.%) and 1 / 2 volume of high-purity argon (purity ≥99.999vol.%), the mixed target powder is placed in a vacuum drying oven for high temperature and vacuum drying, the drying temperature is set to 150℃, the vacuum pressure is set to -0.1MPa, the heating rate is 80℃ / min, the holding time is 1h, and then the temperature is reduced to 25℃ for storage. The obtained powder material is placed in a vacuum bag and vacuumed for storage for standby use;

[0075] S2. The mixed powder obtained in S1 is laid on the surface of a cast AZ91D magnesium alloy substrate and formed by SLM continuous laser, and the scanning strategy is selected as a zigzag scanning mode; the SLM continuous laser power is 100W, the scanning speed is 500mm / s, and the scanning interval is 0.04mm; an ultrafast laser is used for full-width rapid scanning to smooth the SLM surface, the ultrafast laser power is 20W, the pulse frequency is 10kHz, the walking speed is 800cm / s, the overlap rate is 50%, and the coating is formed to the required coating thickness to obtain the active metal surface coating.

[0076] Compared with Example 1, the main difference of this comparative example is that the ultrafast laser targeted material reduction step is not performed.

[0077] Comparative Example 2

[0078] A method for the precise additive and subtractive preparation of active metal surface coatings, comprising the following steps:

[0079] S1. Weigh nanoparticles with a purity of ≥99.90wt.% and micron powder for SLM as raw materials by weight percentage, select 90wt.% pure Zn micron powder with a particle size of 10μm and 10wt.% ZnO nanoparticles with a particle size of 200nm, put them into a planetary ball mill for mixing, the mixing time is selected as 1 hour, the speed is 150r / min, the ball-to-material mass ratio is 2:1, the spherical tank is filled with 1 / 2 volume of anhydrous ethanol (purity ≥99vol.%) and 1 / 2 volume of high-purity argon (purity ≥99.999vol.%) of the spherical tank, the mixed target powder is placed in a vacuum drying oven for high temperature and vacuum drying, the drying temperature is set to 150℃, the vacuum pressure is set to -0.1MPa, the heating rate is 80℃ / min, the holding time is 1h, and then the temperature is reduced to 25℃ for storage. The obtained powder material is placed in a vacuum bag and vacuumed for storage for standby use;

[0080] S2. A cast AZ91D magnesium alloy substrate was directly polished to a mirror finish and placed in an SLM chamber. A femtosecond laser was used to machine dot-matrix holes on the surface of the AZ91D magnesium alloy substrate. The holes had a diameter of 10 μm and a depth of 3 μm, with a minimum spacing of one hole diameter between two holes. The femtosecond laser had a power of 30 W, a pulse frequency of 10 kHz, and a travel speed of 500 cm / s.

[0081] S3. The mixed powder obtained in S1 is spread on the surface of the substrate obtained in S2, and is evenly spread in a manner of filling the microstructure. A ceramic scraper is used to repeatedly spread the mixed powder to ensure that the nanoparticles can completely fall into and fill the deep pits ablated by the ultrafast laser. At the same time, the micron powder can also be evenly spread on the surface of the substrate to be protected. The thickness of each layer of powder is set at 40μm. SLM continuous laser is used for forming, and the scanning strategy is selected as a zigzag scanning mode; the SLM continuous laser power is 80W, the scanning speed is 600mm / s, and the scanning spacing is 0.045mm; an ultrafast laser is used for full-width rapid scanning to smooth the SLM surface. The ultrafast laser power is 10W, the pulse frequency is 20kHz, the walking speed is 600cm / s, and the overlap rate is 60%;

[0082] S4. Repeat the above steps S2 and S3 until the desired coating thickness is reached, thereby obtaining the active metal surface coating.

[0083] Compared with Example 1, the main difference of this comparative example is that the particle size of the micron powder is too small.

[0084] Comparative Example 3

[0085] A method for the precise additive and subtractive preparation of active metal surface coatings, comprising the following steps:

[0086] S1. Weigh nanoparticles with a purity of ≥99.90wt.% and micron powder for SLM as raw materials by weight percentage, select 85wt.% WE43 magnesium powder with a particle size of 40μm and 15wt.% CuO nanoparticles with a particle size of 900nm, put them into a planetary ball mill for mixing, the mixing time is selected as 1 hour, the speed is 150r / min, the ball-to-material mass ratio is 2:1, the spherical tank is filled with 1 / 2 volume of anhydrous ethanol (purity ≥99vol.%) and 1 / 2 volume of high-purity argon (purity ≥99.999vol.%), the mixed target powder is placed in a vacuum drying oven for high temperature and vacuum drying, the drying temperature is set to 150°C, the vacuum pressure is set to -0.1MPa, the heating rate is 80°C / min, the holding time is 1h, and then the temperature is reduced to 25°C for storage. The obtained powder material is placed in a vacuum bag and vacuumed for storage for standby use;

[0087] S2. A cast AZ91D magnesium alloy substrate was directly polished to a mirror finish and placed in an SLM chamber. A femtosecond laser was used to machine dot-matrix holes on the surface of the AZ91D magnesium alloy substrate. The holes had a diameter of 10 μm and a depth of 3 μm, with a minimum spacing of one hole diameter between two holes. The femtosecond laser had a power of 30 W, a pulse frequency of 20 kHz, and a travel speed of 200 cm / s.

[0088] S3. The mixed powder obtained in S1 is spread on the surface of the substrate obtained in S2, and is evenly spread in a manner of filling the microstructure. A ceramic scraper is used to repeatedly spread the mixed powder to ensure that the nanoparticles can completely fall into and fill the deep pits ablated by the ultrafast laser. At the same time, the micron powder can also be evenly spread on the surface of the substrate to be protected. The thickness of each layer of powder is set at 40μm. SLM continuous laser is used for forming, and the scanning strategy is selected as a zigzag scanning method; the SLM continuous laser power is 100W, the scanning speed is 500mm / s, and the scanning spacing is 0.04mm; an ultrafast laser is used for full-width rapid scanning to smooth the SLM surface. The ultrafast laser power is 20W, the pulse frequency is 10kHz, the walking speed is 800cm / s, and the overlap rate is 50%.

[0089] S4. Repeat the above steps S2 and S3 until the desired coating thickness is reached, thereby obtaining the active metal surface coating.

[0090] Compared with Example 1, the main difference of this comparative example is that the particle size of the nanoparticles is too large.

[0091] Comparative Example 4

[0092] A method for the precise additive and subtractive preparation of active metal surface coatings, comprising the following steps:

[0093] S1. Weigh nanoparticles with a purity of ≥99.90wt.% and micron powder for SLM as raw materials by weight percentage, select 90wt.% pure Zn micron powder with a particle size of 40μm and 10wt.% ZnO nanoparticles with a particle size of 200nm, put them into a planetary ball mill for mixing, the mixing time is selected as 1 hour, the speed is 150r / min, the ball-to-material mass ratio is 2:1, the spherical tank is filled with 1 / 2 volume of anhydrous ethanol (purity ≥99vol.%) and 1 / 2 volume of high-purity argon (purity ≥99.999vol.%), the mixed target powder is placed in a vacuum drying oven for high temperature and vacuum drying, the drying temperature is set to 150℃, the vacuum pressure is set to -0.1MPa, the heating rate is 80℃ / min, the holding time is 1h, and then the temperature is reduced to 25℃ for storage. The obtained powder material is placed in a vacuum bag and vacuumed for storage for standby use;

[0094] S2. A cast AZ91D magnesium alloy substrate was directly polished to a mirror finish and placed in an SLM chamber. A femtosecond laser was used to machine dot-matrix holes on the surface of the AZ91D magnesium alloy substrate. The holes had a diameter of 10 μm and a depth of 3 μm, with a minimum spacing of one hole diameter between two holes. The femtosecond laser had a power of 5 W, a pulse frequency of 1 kHz, and a travel speed of 600 cm / s.

[0095] S3. The mixed powder obtained in S1 is spread on the surface of the substrate obtained in S2, and is evenly spread in a manner of filling the microstructure. A ceramic scraper is used to repeatedly spread the mixed powder to ensure that the nanoparticles can completely fall into and fill the deep pits ablated by the ultrafast laser. At the same time, the micron powder can also be evenly spread on the surface of the substrate to be protected. The thickness of each layer of powder is set at 40μm. SLM continuous laser is used for forming, and the scanning strategy is selected as a zigzag scanning mode; the SLM continuous laser power is 80W, the scanning speed is 600mm / s, and the scanning spacing is 0.045mm; an ultrafast laser is used for full-width rapid scanning to smooth the SLM surface. The ultrafast laser power is 10W, the pulse frequency is 20kHz, the walking speed is 600cm / s, and the overlap rate is 60%;

[0096] S4. Repeat the above steps S2 and S3 until the desired coating thickness is reached, thereby obtaining the active metal surface coating.

[0097] Compared with Example 1, the main difference of this comparative example is that the ultrafast laser power and pulse frequency are too small.

[0098] Comparative Example 5

[0099] A method for the precise additive and subtractive preparation of active metal surface coatings, comprising the following steps:

[0100] S1. Weigh nanoparticles with a purity of ≥99.90wt.% and micron powder for SLM as raw materials by weight percentage, select 90wt.% pure Zn micron powder with a particle size of 40μm and 10wt.% ZnO nanoparticles with a particle size of 200nm, put them into a planetary ball mill for mixing, the mixing time is selected as 1 hour, the speed is 150r / min, the ball-to-material mass ratio is 2:1, the spherical tank is filled with 1 / 2 volume of anhydrous ethanol (purity ≥99vol.%) and 1 / 2 volume of high-purity argon (purity ≥99.999vol.%), the mixed target powder is placed in a vacuum drying oven for high temperature and vacuum drying, the drying temperature is set to 150℃, the vacuum pressure is set to -0.1MPa, the heating rate is 80℃ / min, the holding time is 1h, and then the temperature is reduced to 25℃ for storage. The obtained powder material is placed in a vacuum bag and vacuumed for storage for standby use;

[0101] S2. A cast AZ91D magnesium alloy substrate was directly polished to a mirror finish and placed in an SLM chamber. A femtosecond laser was used to machine dot-matrix holes on the surface of the AZ91D magnesium alloy substrate. The holes had a diameter of 10 μm and a depth of 3 μm, with a minimum spacing of one hole diameter between two holes. The femtosecond laser had a power of 50 W, a pulse frequency of 60 kHz, and a travel speed of 600 cm / s.

[0102] S3. The mixed powder obtained in S1 is spread on the surface of the substrate obtained in S2, and is evenly spread in a manner of filling the microstructure. A ceramic scraper is used to repeatedly spread the mixed powder to ensure that the nanoparticles can completely fall into and fill the deep pits ablated by the ultrafast laser. At the same time, the micron powder can also be evenly spread on the surface of the substrate to be protected. The thickness of each layer of powder is set at 40μm. SLM continuous laser is used for forming, and the scanning strategy is selected as a zigzag scanning mode; the SLM continuous laser power is 80W, the scanning speed is 600mm / s, and the scanning spacing is 0.045mm; an ultrafast laser is used for full-width rapid scanning to smooth the SLM surface. The ultrafast laser power is 10W, the pulse frequency is 20kHz, the walking speed is 600cm / s, and the overlap rate is 60%;

[0103] S4. Repeat the above steps S2 and S3 until the desired coating thickness is reached, thereby obtaining the active metal surface coating.

[0104] Compared with Example 1, the main difference of this comparative example is that the ultrafast laser power and pulse frequency are too large.

[0105] Comparative Example 6

[0106] A method for the precise additive and subtractive preparation of active metal surface coatings, comprising the following steps:

[0107] S1. Weigh nanoparticles with a purity of ≥99.90wt.% and micron powder for SLM as raw materials by weight percentage, select 90wt.% pure Zn micron powder with a particle size of 50μm and 10wt.% ZnO nanoparticles with a particle size of 100nm, put them into a planetary ball mill for mixing, the mixing time is selected as 1 hour, the speed is 150r / min, the ball-to-material mass ratio is 2:1, the spherical tank is filled with 1 / 2 volume of anhydrous ethanol (purity ≥99vol.%) and 1 / 2 volume of high-purity argon (purity ≥99.999vol.%) of the spherical tank, the mixed target powder is placed in a vacuum drying oven for high temperature and vacuum drying, the drying temperature is set to 150℃, the vacuum pressure is set to -0.1MPa, the heating rate is 80℃ / min, the holding time is 1h, and then the temperature is reduced to 25℃ for storage. The obtained powder material is placed in a vacuum bag and vacuumed for storage for standby use;

[0108] S2. A cast AZ91D magnesium alloy substrate was directly polished to a mirror finish and placed in an SLM chamber. A femtosecond laser was used to machine dot-matrix holes on the surface of the AZ91D magnesium alloy substrate. The holes had a diameter of 10 μm and a depth of 3 μm, with a minimum spacing of one hole diameter between two holes. The femtosecond laser had a power of 30 W, a pulse frequency of 20 kHz, and a travel speed of 200 cm / s.

[0109] S3. The mixed powder obtained in S1 is spread on the surface of the substrate obtained in S2, and is evenly spread in a manner of filling the microstructure. A ceramic scraper is used to repeatedly spread the mixed powder to ensure that the nanoparticles can completely fall into and fill the deep pits ablated by the ultrafast laser. At the same time, the micron powder can also be evenly spread on the surface of the substrate to be protected. The thickness of each layer of powder is set at 40μm. SLM continuous laser is used for forming, and the scanning strategy is selected as a zigzag scanning method; the SLM continuous laser power is 200W, the scanning speed is 50mm / s, and the scanning spacing is 0.02mm; an ultrafast laser is used for full-width rapid scanning to smooth the SLM surface. The ultrafast laser power is 20W, the pulse frequency is 10kHz, the walking speed is 800cm / s, and the overlap rate is 50%.

[0110] S4. Repeat the above steps S2 and S3 until the desired coating thickness is reached, thereby obtaining the active metal surface coating.

[0111] Compared with Example 1, the main difference of this comparative example is that the SLM continuous laser power and scanning speed are too large.

[0112] Comparative Example 7

[0113] A method for the precise additive and subtractive preparation of active metal surface coatings, comprising the following steps:

[0114] S1. Weigh the SLM micron powder with a purity of ≥99.90wt.% as the raw material, select AZ91D magnesium alloy micron powder with a particle size of 20μm, put it into a planetary ball mill for mixing, the mixing time is selected as 1 hour, the speed is 150r / min, the ball-to-material mass ratio is 2:1, and the spherical tank is filled with 1 / 2 volume of anhydrous ethanol (purity ≥99vol.%) and 1 / 2 volume of high-purity argon (purity ≥99.999vol.%). The mixed target powder is placed in a vacuum drying oven for high temperature and vacuum drying. The drying temperature is set to 150℃, the vacuum pressure is set to -0.1MPa, the heating rate is 80℃ / min, the holding time is 1h, and then the temperature is reduced to 25℃ for storage. The obtained powder material is placed in a vacuum bag and vacuumed for storage for standby use;

[0115] S2. AZ91D magnesium alloy was first formed using the SLM method. The entire substrate surface was then de-powdered using an ultrafast laser. The ultrafast laser had a power of 20W, a pulse frequency of 10kHz, a travel speed of 800cm / s, and an overlap ratio of 50%. A femtosecond laser was used to machine dot-matrix holes on the surface of the AZ91D magnesium alloy substrate. The holes had a diameter of 20μm and a depth of 5μm, with a minimum spacing of one hole diameter between two holes. The femtosecond laser had a power of 30W, a pulse frequency of 20kHz, and a travel speed of 200cm / s.

[0116] S3. The powder obtained in S1 is spread on the surface of the substrate obtained in S2, and is evenly spread in a manner of filling the microstructure. A ceramic scraper is used to repeatedly spread the mixed powder to ensure that the nanoparticles can completely fall into and fill the deep pits ablated by the ultrafast laser. At the same time, the micron powder can also be evenly spread on the surface of the substrate to be protected. The thickness of each layer of powder is set at 40μm. SLM continuous laser is used for forming, and the scanning strategy is selected as a zigzag scanning method; the SLM continuous laser power is 100W, the scanning speed is 500mm / s, and the scanning spacing is 0.04mm; an ultrafast laser is used for full-width rapid scanning to smooth the SLM surface. The ultrafast laser power is 20W, the pulse frequency is 10kHz, the walking speed is 800cm / s, and the overlap rate is 50%.

[0117] S4. Repeat the above steps S2 and S3 until the desired coating thickness is reached, thereby obtaining the active metal surface coating.

[0118] Compared with Example 1, the main difference of this comparative example is that no nanoparticles are added.

[0119] The setting parameters of each embodiment and comparative example are shown in Table 1 below:

[0120] Table 1 Setting parameters of Examples 1-4 and Comparative Examples 1-7

[0121]

[0122]

[0123] The functional coating on the surface of the active metal material of Example 1 was characterized and analyzed, and the results are shown below:

[0124] Figure 2 For this application, the microstructure of the functional coating on the surface of the active metal material is shown in Figure 2. Figure 2As shown in the figure, the nanoparticles after SLM forming are precisely distributed according to the design of the coating, and the grain structure after forming is fine. On the one hand, the nanoparticles promote the formation of equiaxed crystals in the form of nucleating agents. On the other hand, the enriched nanoparticles play a role in pinning dislocations and dispersion strengthening, thereby improving its wear resistance and corrosion resistance.

[0125] The test results of the other embodiments are basically consistent with it.

[0126] Figure 3 This is an SEM image of the active metal surface coating of Comparative Example 1 of the present invention. In Comparative Example 1, the micronized powders and nanoparticles required for the target coating were mechanically mixed according to the recommended process. The mixed powders were then directly formed using SLM without the ultrafast laser targeted subtraction step. However, due to significant Marangoni disturbances in the melt pool during SLM, the nanoparticles were randomly distributed in the formed coating, preventing precise distribution.

[0127] Figure 4 This is an SEM image of the active metal surface coating from Comparative Example 2 of the present invention. In Comparative Example 2, the particle size of the micronized powder used for SLM was selected to be approximately 10 μm, and all other parameters remained unchanged before subsequent operations were performed. Because the powder was too fine, it blocked the proper filling of the nanoparticles, preventing them from filling the holes machined by the femtosecond laser. This resulted in the formation of unmelted particles, causing compositional segregation and ultimately failing to achieve the desired coating function.

[0128] Figure 5 This is a microscopic image of the active metal surface coating from Comparative Example 3 of the present invention. In Comparative Example 3, the nanoparticle size was limited to approximately 900 nm, while all other parameters remained unchanged, and subsequent operations were performed. Due to the excessively large particle size of the nanopowder, the formed coating contained numerous pores surrounding the reinforcing particles, significantly reducing the coating's hardness and corrosion resistance, making it unable to achieve its desired function.

[0129] Figure 6 This is a microscopic image of the active metal surface coating from Comparative Example 4 of the present invention. In Comparative Example 4, the femtosecond subtractive process parameters were set outside the recommended range: laser power = 5W, pulse frequency = 1kHz, and travel speed = 600cm / s. All other parameters remained unchanged. Due to the low output energy density of the femtosecond laser, the holes ablated on the surface lacked sufficient energy, resulting in uneven holes and insufficient depth, making it difficult to meet the requirements for SLM coating formation.

[0130] Figure 7 This is a microscopic morphology of the active metal surface coating of Comparative Example 5 of the present invention. Due to the excessive laser power used in Comparative Example 5, Figure 7As shown in the figure, the impacted holes are not only deep and wide, but also have a wider melt width. In addition, the pulse frequency used is too high, resulting in a narrow interval between adjacent holes. Some holes are even directly covered with each other. As a result, in the next powder spreading process, the nanoparticles cannot fall into the desired holes in an orderly manner. Instead, they are concentrated in the overlapping areas of the holes in large flakes, which ultimately leads to the failure of coating formation.

[0131] Figure 8 Figure 6 shows the macro- and microscopic morphology of the active metal surface coating in Comparative Example 6 of the present invention. The SLM process parameters in Comparative Example 6 were set outside the recommended range. Specifically, at laser power = 200W, scanning speed = 50mm / s, and scanning pitch = 0.02mm, the excessively high energy density input resulted in noticeable bulging on the surface of the SLM-formed coating. Furthermore, the excessively high energy density left numerous holes and even cracks within the coating, making it difficult to meet the requirements for SLM-formed coatings.

[0132] Performance tests were performed on Examples 1 to 4 and Comparative Examples 1 to 7. The specific test methods are as follows:

[0133] Friction performance test

[0134] The SLM coating samples prepared in Examples 1-4 were subjected to average microhardness testing. The Vickers microhardness of the samples was measured using a microhardness tester (Leitz Wetzlar, Germany) with a load of 100 g and a loading time of 20 s. The surface roughness of the SLM sample test surface was polished to less than 0.15 μm. The microhardness values ​​at different locations on the SLM-formed coating sample surface were measured 10 times, and the average value was calculated.

[0135] Biological performance testing

[0136] The SLM coating samples prepared in Examples 1 to 4, the coating samples prepared in Comparative Example 7, the SLM-molded AZ91D, and the cast AZ91D samples were subjected to in vitro cytotoxicity, proliferation, and differentiation tests using MC3T3-E1 osteoblast precursor cells in accordance with the international standard ISO 10993-5. Before use in the cytotoxicity test, a liquid extract of the sample was prepared (37°C, containing 10% FBS (v / v), in α-MEM for 3 cm 2 / mL) and filter sterilized, and the cytotoxicity was evaluated using a cell counting kit-8 (CCK-8). BMSCs were plated at 1×10 4The density of each cell is seeded on 96-well plates for one day, and then the liquid extract of the α-MEM (positive control, providing reproducible cytotoxic reaction) containing medical grade polyethylene (negative control, no cytotoxicity) and 10% FBS (v / v) and 10% dimethyl sulfoxide (DMSO) and the liquid extract of the sample from each group (100 μ L / well) are replaced with culture medium for 1 day, 3 days, 5 days and 7 days. Subsequently, 10 μ L of CCK-8 solution are added to each well of the plate, and the plate is incubated under illumination for two hours. The absorbance at 450 nm is measured. The value of the negative control well is averaged and used as 100% cell viability. Then all other values ​​are averaged relative to their group and compared with the negative control group.

[0137] The SLM coating samples prepared in Examples 1 to 4, the coating sample prepared in Comparative Example 7, the SLM-molded AZ91D, and the cast AZ91D samples were tested for anti-Staphylococcus aureus. The test method is as follows:

[0138] LB liquid medium - Use a graduated cylinder to measure 100 mL of distilled water and pour it into a 250 mL reagent bottle. Use an analytical electronic balance to weigh 2.5 g of LB broth medium and add it to the mixture. Sterilize it in a high-temperature and high-pressure steam sterilizer at 121°C for 15 minutes and set aside.

[0139] LB solid medium—Use a graduated cylinder to measure 100 mL of distilled water into a 250 mL reagent bottle. Using an analytical electronic balance, weigh 2.5 g of LB broth and 1.5 g of agar powder. Add these to the mixture and mix thoroughly. Sterilize in an autoclave at 121°C for 15 minutes. Once the medium cools to approximately 40-50°C, use an electric pipette to transfer 15 mL of the medium into a disposable sterile dish.

[0140] Take two 12mL bacterial culture tubes and add 3mL of LB liquid medium to each. Pick a single colony from the solid culture medium of Staphylococcus aureus and add it to the liquid medium. The other tube serves as a blank control. Place the tube in a constant temperature shaker (37°C, 200 rpm) and shake and culture overnight (15 hours).

[0141] Wipe the surface of the sample with 75% alcohol cotton, and after drying, place it in a disposable culture dish with the corresponding number, sterilize it with ultraviolet light on both sides for 30 minutes, and set aside.

[0142] Dilute Staphylococcus aureus to 106 CFU / mL using LB liquid medium. Add 50 μL of this diluted solution to the sample surface. For the control group, leave the sample untouched. Cover with film and gently press. Incubate in a constant temperature incubator at 37°C for 18 hours.

[0143] After incubation, rinse with 2 mL of sterile PBS and make serial 10-fold dilutions with PBS. Spread 100 μL of the dilution evenly on LB solid medium. Incubate in a 37°C incubator for 18 hours. Remove the plate, photograph, and record the number of colonies. Count the colonies and calculate the antibacterial rate according to GB4789.2-2016.

[0144] Figure 9 Figure 2 is a cell staining diagram of Example 1 of the present invention and the AZ91D sample formed by SLM. Figure 9 As shown, the left is the leachate of the SLM-molded AZ91D sample, and the right is the leachate of Example 1 of the present invention. When the leachate of the materials treated and untreated by the present method after immersion for 1 day is used to culture MC3T3-E1 osteoblasts, it can be found that more cells in the coating survive, while a small number of dead cells appear in the untreated material. The reason for this is that on the one hand, the material without coating protection degrades faster, resulting in a higher pH value in the leachate, which is alkaline and not conducive to cell growth; on the other hand, since the substrate does not have Cu, Zn and other ions in the coating that can promote osteoblast growth, live-dead cell staining found that a few dead cells appeared in the material not treated by the present method.

[0145] Figure 10 : is the antibacterial effect diagram of Example 1 of the present invention and Comparative Example 7. Figure 10 As shown, the left is the leachate of Comparative Example 7, and the right is the leachate of Example 1 of the present invention. After the coating leachate prepared by this method is co-cultured with Staphylococcus aureus for 7 days, the antibacterial effect of the coating containing nano ZnO and CuO is significantly improved compared with the control group. This is because the nano oxides can penetrate the surface membrane of the bacteria and enter the bacteria to exert their efficacy, thereby killing the bacteria. Therefore, their antibacterial performance is significantly improved, while the antibacterial effect of the leachate of the material without nano particles is relatively general.

[0146] The specific results are shown in Table 2 below:

[0147] Table 2 Test results of Examples 1-4 and Comparative Example 7, SLM-molded AZ91D and cast AZ91D

[0148]

[0149]

[0150] As can be seen from the above table, the hardness of the functional coating samples on the surface of active metal materials prepared in various embodiments of the present invention is increased by about 10% to 88% compared with traditional and SLM formed methods, and the average friction coefficient is reduced by about 50%. At the same time, the degradation rate, antibacterial properties and cell survival rate of the coating are significantly improved compared with the parts prepared by traditional methods. It is an innovative channel for achieving the simultaneous promotion of mechanical and biological properties, and provides excellent potential and good application prospects for magnesium alloy medical devices in surface protection and functionalization.

[0151] The hardness, wear resistance and biological properties of the coating prepared in Comparative Example 7 without adding nanoparticles are basically the same as those of the coating directly formed by SLM. The average hardness of the SLM AZ91D sample is 90.2±3.37HV 0.1 The friction and wear coefficient is 0.44±0.055, while the average hardness of the coating in the comparative example is only 89.5±2.81HV after 3 measurements. 0.1 The friction and wear coefficient is 0.45±0.012, and other physical and chemical properties are basically the same, and do not play a greater strengthening role.

[0152] In summary, the present invention prepares functional coatings on the surface of active metal materials by alternating ultrafast laser point-by-point subtraction and SLM technologies. The coating is convenient, fast, simple, efficient and flexible to use. The prepared coating has few defects such as pores and cracks, and the grains are extremely small. It is mainly composed of dense equiaxed crystal structure and is metallurgically bonded to the matrix. The added nanoparticles not only act as in-situ nucleating agents to promote grain refinement and dispersion strengthening, but also, due to the precise distribution of nanoparticles within the coating, it can provide a reliable method for the controllable degradation and biological function expression of the coating. While achieving the improvement of mechanical effects such as particle enhancement and in-situ strengthening, it also achieves the controlled release of functional nanoparticles. The resulting coating can achieve controllable thickness and metallurgical bonding. The nanoparticles are precisely distributed within the coating according to the designer's ideas, and the required coating efficacy can be expressed in sequence according to the designer's ideas, meeting its application needs in high-end medical and other fields.

[0153] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for the precise preparation of functional coatings on the surface of active metal materials by additive and subtractive methods, characterized in that: The following steps are involved: S1. Select micronized powder with a particle size of 20-75 μm and nanoparticles with a particle size of 10-500 nm, mix them evenly, vacuum dry them, and set aside; S2. Using an ultrafast laser to process microstructures on the substrate surface; the ultrafast laser power is 10-60W, the pulse frequency is 5-50kHz, and the travel speed is 100-500cm / s; S3. The mixed powder obtained in S1 is laid on the surface of the substrate obtained in S2, and is evenly spread in a manner to fill the microstructure, and formed using a SLM continuous laser; the SLM continuous laser power is 50~150W, the scanning speed is 100~800mm / s, and the scanning pitch is 0.03~0.05mm; S4 repeat the above steps S2, S3, until the desired coating thickness is formed, to obtain the active metal material surface functional coating; The ratio of the micron powder and the nanoparticles in S1 is (80-95):(5-20); The microstructure of S2 is a dot matrix hole groove, the hole diameter is 3~20μm, the depth is 1~5μm, and the minimum distance between two holes is 1 hole diameter.

2. A method for accurately preparing functional coatings on the surface of active metal materials by adding or subtracting materials according to claim 1, characterized in that: The sphericity of the micronized powder in S1 is ≥85%.

3. A method for accurately preparing functional coatings on the surface of active metal materials by adding or subtracting materials according to claim 1, characterized in that: The uniform mixing in S1 is performed by planetary ball milling; the planetary ball milling mixing time is 0.5 to 1.5 hours, the rotation speed is 100 to 300 r / min, and the ball-to-material mass ratio is (1 to 5):

1.

4. A method for accurately preparing functional coatings on the surface of active metal materials by adding or subtracting materials according to claim 1, characterized in that: The vacuum drying temperature in S1 is 100-200° C., and the pressure is -0.08-0.1 MPa.

5. A method for accurately preparing functional coatings on the surface of active metal materials by adding or subtracting materials according to claim 1, characterized in that: The ultrafast laser described in S2 is a femtosecond laser and / or a picosecond laser.

6. A method for accurately preparing functional coatings on the surface of active metal materials by adding or subtracting materials according to claim 1, characterized in that: S2 The substrate is an active metal substrate; the active metal is one or more of titanium-based materials, magnesium-based materials, iron-based materials, and zinc-based materials.

7. A method for accurately preparing functional coatings on the surface of active metal materials by adding or subtracting materials according to claim 1, characterized in that: After the SLM continuous laser forming is performed in S3, the method further includes the step of using an ultrafast laser to perform full-width rapid scanning.

8. A functional coating on the surface of an active metal material, characterized in that: Prepared by the preparation method according to any one of claims 1 to 7.

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