Laser additive manufacturing system AMD method for magnesium-based composite material

Abstract

A laser additive manufacturing system and method for a magnesium-based composite material. The system comprises a laser adjuster (1), a laser (2), a forming cover (3), an oxygen content adjuster (4), an inert gas cylinder (5), a powder feeder (6), a substrate (7) and a wire feeder (8), wherein the laser adjuster is used for controlling laser processing parameters of the laser; the laser is connected to a laser processing head (10) by means of an optical fiber (9); the oxygen content adjuster is in communication with the forming cover, so as to control the oxygen content of a processing environment in the forming cover; the inert gas cylinder and the powder feeder both pass through the forming cover to be connected to the laser processing head; the substrate is located inside the forming cover; the wire feeder is connected to a wire feeding head (12) by means of a wire feeding tube (11); the wire feeding head passes through the forming cover to perform laser additive manufacturing for a magnesium-based composite material, together with the laser processing head; and a real-time cooling sleeve (13) is also mounted on the wire feeding tube. Also provided are a method for preparing a magnesium-based composite material using the laser additive manufacturing system for the magnesium-based composite material, and a prepared magnesium-based composite material. By means of the manufacturing system and method, the additive processing of wires and powder is realized, and a magnesium-based composite material with a good mechanical property is prepared.

Description

A laser additive manufacturing system and method for magnesium-based composite materials Technical Field

[0001] The present invention relates to the technical field of laser additive manufacturing, and in particular to a laser additive manufacturing system and method for magnesium-based composite materials. Background Art

[0002] Magnesium alloys have the advantages of light weight, high specific strength and specific stiffness, excellent damping and vibration reduction, anti-electromagnetic interference and casting performance, and have received continuous attention from aerospace, transportation, electronics, biomedicine and other fields. However, due to its poor corrosion resistance and wear resistance, insufficient high-temperature strength and high-temperature creep resistance, the widespread application of magnesium alloys is severely restricted. Studies have found that by utilizing the synergistic reinforcement effect, the magnesium-based composite materials formed by combining hard ceramic particles with a magnesium alloy matrix can significantly improve the high-temperature strength, wear resistance and creep resistance of magnesium alloys. The existing preparation methods of magnesium-based composite materials can be divided into liquid phase and solid phase, mainly including stirring casting, extrusion casting, powder metallurgy, stir friction processing, etc., which are difficult to meet the industrial field's demand for the rapid digital preparation of magnesium-based products with complex structures and high performance.

[0003] Laser additive manufacturing (LAM) is a rapidly developing digital advanced manufacturing technology that has been widely used in the rapid preparation of metal materials such as titanium alloys, stainless steel, and nickel-based alloys, as well as oxide ceramics. It includes two methods: Selective Laser Melting (SLM) and Laser Directed Energy Deposition (LDED). This technology uses a high-energy laser to melt metal powder or wire layer by layer, forming a tiny molten pool that then rapidly solidifies, gradually forming a three-dimensional part along a pre-planned path. It has the characteristics of short cycle times, high precision and flexibility, and the ability to prepare complex structural parts. It is extremely valuable in the rapid preparation of magnesium-based materials. In recent years, laser additive manufacturing of magnesium-based materials has become a research hotspot in the field of additive manufacturing.

[0004] However, there are certain defects in the existing preparation methods. For example, powder-based laser additive manufacturing of magnesium-based composites has the risk of flammability and explosion. The strong oxygen affinity of Y and Zr elements aggravates the oxidation of magnesium-based powders, easily forming defects such as spheroidization, pores, inclusions and cracks, which limits the performance improvement of the material; the use of ball milling method to mix and reinforce ceramic particles and magnesium powder has limited effect, the content of particles adhered to the surface of magnesium powder is small and the mixing is uneven; the method of using sol-gel method to prepare laser additive manufacturing magnesium-based composite protective agent significantly increases the complexity and cost of the process.

[0005] Summary of the Invention

[0006] In light of this, it is necessary to provide a laser additive manufacturing system and method for magnesium-based composite materials to address the above-mentioned issues. Compared with existing preparation methods, the system and preparation method of the present invention can reduce risks in the preparation process, simplify the process flow, reduce costs, and improve the quality and performance of the composite materials.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a laser additive manufacturing system for magnesium-based composite materials, the system comprising a laser regulator, a laser, a forming hood, an oxygen content regulator, an inert gas bottle, a powder feeder, a substrate and a wire feeder; the laser regulator is used to control the laser processing parameters of the laser; the laser is connected to a laser processing head via an optical fiber; the oxygen content regulator is communicated with the forming hood to control the oxygen content of the processing environment in the forming hood; the inert gas bottle and the powder feeder are respectively connected to the laser processing head through the forming hood; the substrate is located in the forming hood; the wire feeder is connected to a wire feeding head via a wire feeding tube; the wire feeding head passes through the forming hood and the laser processing head to perform laser additive manufacturing of magnesium-based composite materials on the substrate; a real-time cooling sleeve is installed on the wire feeding tube.

[0009] Furthermore, the laser is a YLS-6000-S2T fiber laser.

[0010] Furthermore, the laser processing head is a YC-52 cladding head.

[0011] Furthermore, the powder feeder is a Twin-150 double-barrel powder feeder.

[0012] Furthermore, the wire feeder is a TW-630 multi-function wire feeder.

[0013] In a second aspect, the present invention provides a method for laser additive manufacturing of a magnesium-based composite material, comprising the following steps:

[0014] Step 1: pre-treat the substrate; select magnesium alloy wire and ceramic powder as the initial materials for additive manufacturing, and pre-treat the ceramic powder;

[0015] Step 2: Place the pre-treated ceramic powder in the powder feeder, place the magnesium alloy wire in the wire feeder, adjust the position of the wire feeder head and the laser processing head, and adjust the laser regulator to set the laser additive manufacturing processing parameters;

[0016] Step 3: Open the inert gas bottle to fill the processing environment in the forming hood with inert gas, and use the oxygen content regulator to control the oxygen content of the processing environment to no more than 120 ppm; start the powder feeder, wire feeder and laser in sequence, and perform additive processing on the magnesium alloy wire and ceramic powder according to the predetermined trajectory to manufacture a magnesium-based composite formed part that meets the requirements on the magnesium alloy substrate.

[0017] Furthermore, the substrate in step 1 is a magnesium alloy substrate, and the substrate is pretreated by first sandblasting to remove oxide scale, and then using ethanol and an air gun to clean impurities on the surface of the substrate.

[0018] Furthermore, the ceramic powder in step 1 is SiC, TiC or Al2O3 / TiB2 ceramic powder, and the ceramic powder is pretreated by placing it in an electrically heated vacuum drying oven at 100-180°C for 5-10 hours, with the vacuum degree maintained at 10 -4 ~10 -5 Pa.

[0019] Furthermore, in step 1, the diameter of the magnesium alloy wire is 1.2 to 3.5 mm, and the particle size of the ceramic powder is 20 to 70 μm.

[0020] Furthermore, the position is adjusted in step 2 to set the angle between the wire feeding head and the laser processing head to 25-65°, adjust the working distance between the bottom of the wire feeding head and the surface of the magnesium alloy substrate to 0.5-1.5 mm, and adjust the working distance between the bottom of the laser processing head and the surface of the magnesium alloy substrate to 5-10 mm.

[0021] Furthermore, the processing parameters of laser additive manufacturing in step 2 include: laser power density of 10 3 ~10 4 W / cm 2 , the scanning speed is 450-750 mm / min, the layer height is 0.3-0.6 mm, the powder feeding rate is 0.11-0.88 g / min, the wire feeding speed is 500-1000 mm / min; the temperature of the real-time cooling jacket on the wire feeding tube is 15-45°C.

[0022] Furthermore, in step 3, the inert gas bottle contains argon or nitrogen with a purity of 99.99%.

[0023] The beneficial effects of the present invention are:

[0024] 1. The laser additive manufacturing system for magnesium-based composite materials provided by the present invention has a simple structure and is easy to operate. It can realize additive processing of wires and powders and prepare magnesium-based composite materials with good mechanical properties.

[0025] 2. The laser additive manufacturing method of magnesium-based composite materials provided by the present invention screens the types of initial materials, uses continuous laser as the energy source for additive manufacturing, and ensures that the thermal reaction of the molten pool is slowed down during the forming process through real-time cooling, the sample shrinks evenly, and the forming quality of the sample is improved. In addition, by optimizing the process parameters, the present invention reduces the heat-affected zone and refines the microstructure, and the prepared samples have good mechanical properties and density. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIG1 is a schematic diagram of a laser additive manufacturing system for magnesium-based composite materials in Example 1;

[0027] In the figure, 1-laser regulator; 2-laser; 3-forming cover; 4-oxygen content regulator; 5-inert gas bottle; 6-powder feeder; 7-substrate; 8-wire feeder; 9-optical fiber; 10-laser processing head; 11-wire feeding tube; 12 wire feeding head; 13-real-time cooling jacket. DETAILED DESCRIPTION

[0028] To make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be further clearly and completely described below in conjunction with the embodiments of the present invention. It should be noted that the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0029] In the description of the present invention, it should be noted that if specific conditions are not specified in the examples, the experiments were carried out according to conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used, if the manufacturer is not specified, are all conventional products that can be purchased commercially.

[0030] Example 1

[0031] As shown in FIG1 , a laser additive manufacturing system for magnesium-based composite materials includes a laser regulator 1, a laser 2, a forming hood 3, an oxygen content regulator 4, an inert gas bottle 5, a powder feeder 6, a substrate 7, and a wire feeder 8. The laser regulator 1 is used to control the laser processing parameters of the laser 2. The laser 2 is connected to a laser processing head 10 via an optical fiber 9. The oxygen content regulator 4 is connected to the forming hood 3 to control the oxygen content of the processing environment in the forming hood 3. The inert gas bottle 5 and the powder feeder 6 pass through the forming hood 3. It is connected to the laser processing head 10; the substrate 7 is located in the forming cover 3; the wire feeder 8 is connected to a wire feeding head 12 through a wire feeding tube 11; the wire feeding head 12 passes through the forming cover 3 and performs laser additive manufacturing of magnesium-based composite materials on the substrate 7 with the laser processing head 10; a real-time cooling jacket 13 is installed on the wire feeding tube 11; wherein, the laser is a YLS-6000-S2T fiber laser, the laser processing head is a YC-52 cladding head, the powder feeder is a Twin-150 double-barrel powder feeder, and the wire feeder is a TW-630 multi-function wire feeder.

[0032] Example 2

[0033] A method for laser additive manufacturing of a magnesium-based composite material, using the laser additive manufacturing system for the magnesium-based composite material described in Example 1, comprises the following steps:

[0034] Step 1: Pre-treat the AZ91D magnesium alloy substrate; the pre-treatment method is to first sandblast to remove the oxide scale, and then use ethanol and an air gun to clean the impurities on the surface of the substrate; select AZ91D magnesium alloy wire with a diameter of 1.8 mm and SiC ceramic powder with a particle size of 20-70 μm as the initial materials for additive manufacturing, and pre-treat the SiC ceramic powder; the pre-treatment method of the SiC ceramic powder is to place it in an electric heating vacuum drying oven at 120 ° C for 6 hours, and the vacuum degree is maintained at 10 -4 Pa;

[0035] Step 2: Place the pretreated SiC ceramic powder in the powder feeder, place the AZ91D magnesium alloy wire in the wire feeder, adjust the angle between the wire feeder head and the laser processing head to 25°, adjust the working distance between the bottom of the wire feeder head and the surface of the AZ91D magnesium alloy substrate to 0.5 mm, and adjust the working distance between the bottom of the laser processing head and the surface of the AZ91D magnesium alloy substrate to 8 mm; adjust the laser regulator to set the processing parameters of laser additive manufacturing as follows: laser power density 10 3 W / cm 2 , scanning speed is 500mm / min, layer height is 0.4mm, powder feeding rate is 0.25g / min, wire feeding speed is 600mm / min; the temperature of the real-time cooling jacket on the wire feeding tube is 15℃;

[0036] Step 3: Open the inert gas bottle to fill the processing environment in the forming hood with argon gas with a purity of 99.99%, and use the oxygen content regulator to control the oxygen content of the processing environment to no more than 120 ppm; start the powder feeder, wire feeder and laser in sequence, and perform additive processing on the AZ91D magnesium alloy wire and SiC ceramic powder according to the predetermined trajectory to manufacture a magnesium-based composite formed part that meets the requirements on the AZ91D magnesium alloy substrate.

[0037] Example 3

[0038] A method for laser additive manufacturing of a magnesium-based composite material, using the laser additive manufacturing system for the magnesium-based composite material described in Example 1, comprises the following steps:

[0039] Step 1: Pre-treat the AZ31 magnesium alloy substrate; the pre-treatment method is to first sandblast to remove the oxide scale, and then use ethanol and air gun to clean the impurities on the surface of the substrate; select AZ31 magnesium alloy wire with a diameter of 2.5 mm and TiC ceramic powder with a particle size of 20-70 μm as the initial materials for additive manufacturing, and pre-treat the TiC ceramic powder; the pre-treatment method of the TiC ceramic powder is to place it in an electric heating vacuum drying oven at 120 ° C for 6 hours, and the vacuum degree is maintained at 10 -4 Pa;

[0040] Step 2: Place the pretreated TiC ceramic powder in the powder feeder, place the AZ31 magnesium alloy wire in the wire feeder, adjust the angle between the wire feeder head and the laser processing head to 30°, adjust the working distance between the bottom of the wire feeder head and the surface of the AZ31 magnesium alloy substrate to 0.6 mm, and adjust the working distance between the bottom of the laser processing head and the surface of the AZ31 magnesium alloy substrate to 8 mm; adjust the laser regulator to set the processing parameters of laser additive manufacturing as follows: laser power density 10 3 W / cm 2 , scanning speed is 550mm / min, layer height is 0.35mm, powder feeding rate is 0.45g / min, wire feeding speed is 700mm / min; the temperature of the real-time cooling jacket on the wire feeding tube is 30℃;

[0041] Step 3: Open the inert gas bottle to fill the processing environment in the forming hood with argon gas with a purity of 99.99%, and control the oxygen content of the processing environment to be no more than 120 ppm through the oxygen content regulator; start the powder feeder, wire feeder and laser in sequence, and perform additive processing on the AZ31 magnesium alloy wire and TiC ceramic powder according to the predetermined trajectory to manufacture a magnesium-based composite formed part that meets the requirements on the AZ31 magnesium alloy substrate.

[0042] Example 4

[0043] A method for laser additive manufacturing of a magnesium-based composite material, using the laser additive manufacturing system for the magnesium-based composite material described in Example 1, comprises the following steps:

[0044] Step 1. Pretreat the Mg-15Gd-1Al-0.4Zr magnesium alloy substrate; the pretreatment method is to first sandblast to remove the oxide scale, and then use ethanol and an air gun to clean the impurities on the surface of the substrate; select Mg-15Gd-1Al-0.4Zr magnesium alloy wire with a diameter of 3.5 mm and Al2O3 / TiB2 ceramic powder with a particle size of 20-70 μm as the initial materials for additive manufacturing, and pretreat the Al2O3 / TiB2 ceramic powder; the pretreatment method of the Al2O3 / TiB2 ceramic powder is to place it in an electric heating vacuum drying oven at 120°C for 8 hours, and the vacuum degree is maintained at 10 -5 Pa;

[0045] Step 2: Place the pretreated Al2O3 / TiB2 ceramic powder in the powder feeder, place the Mg-15Gd-1Al-0.4Zr magnesium alloy wire in the wire feeder, adjust the angle between the wire feeder head and the laser processing head to 65°, adjust the working distance between the bottom of the wire feeder head and the surface of the Mg-15Gd-1Al-0.4Zr magnesium alloy substrate to 1.5 mm, and adjust the working distance between the bottom of the laser processing head and the surface of the Mg-15Gd-1Al-0.4Zr magnesium alloy substrate to 8 mm; adjust the laser regulator to set the processing parameters of laser additive manufacturing as follows: laser power density 10 4 W / cm 2 , scanning speed is 750mm / min, layer height is 0.6mm, powder feeding rate is 0.88g / min, wire feeding speed is 1000mm / min; the temperature of the real-time cooling jacket on the wire feeding tube is 45℃;

[0046] Step 3: Open the inert gas bottle to fill the processing environment in the forming hood with argon gas with a purity of 99.99%, and adjust the oxygen content of the processing environment to no more than 120 ppm through the oxygen content regulator; start the powder feeder, wire feeder and laser in sequence, and perform additive processing on the Mg-15Gd-1Al-0.4Zr magnesium alloy wire and Al2O3 / TiB2 ceramic powder according to a predetermined trajectory to manufacture a magnesium-based composite formed part that meets the requirements on the Mg-15Gd-1Al-0.4Zr magnesium alloy substrate.

[0047] Comparative Example 1

[0048] The forming experiments of AZ91D magnesium alloy powder and SiC ceramic powder were carried out using a laser powder feeding additive manufacturing system. The steps are as follows:

[0049] Step 1: Place AZ91D magnesium alloy powder with a particle size of 110 μm into powder feeder 1 and set the powder feeding rate to 4 g / min. Place SiC ceramic powder with a particle size of 20 to 70 μm into powder feeder 2 and set the powder feeding rate to 0.5 g / min. The laser power of the laser powder feeding additive manufacturing system is 230 W, the scanning speed is 690 mm / min, and the layer height is 0.4 mm.

[0050] Step 2: Place an AZ91D magnesium alloy substrate with a size of 150mm×150mm×15mm in the laser powder feeding additive manufacturing system, start powder feeder 1 and powder feeder 2, and form a magnesium-based composite material sample layer by layer on the substrate according to the predetermined trajectory.

[0051] Results: AZ91D magnesium alloy powder was severely oxidized, the printing process was interrupted, and the forming failed.

[0052] Comparative Example 2

[0053] The SLM system was used to conduct forming experiments on AZ31 magnesium alloy powder and TiC ceramic powder. The steps are as follows:

[0054] Step 1: Select AZ31 magnesium alloy powder with a particle size of 20-60 μm and TiC ceramic powder, mix them evenly in a volume ratio of 11:1, and place the mixed powder in a powder tank;

[0055] Step 2: Spread the powder in the powder tank onto the forming cylinder and adjust the layer thickness to 35μm;

[0056] Step 3: SLM forming of magnesium-based composite materials was performed under high-purity argon protection, with the spot diameter set to 30 μm, the laser power to 260 W, the scanning speed to 670 mm / s, and the scanning pitch to 0.03 mm;

[0057] Step 4: After forming, turn off the forming system, clean the residual powder and remove the support structure.

[0058] Results: AZ31 magnesium alloy and TiC ceramic powders were severely oxidized and had poor forming quality.

[0059] Comparative Example 3

[0060] The arc additive manufacturing system was used to perform forming experiments on Mg-15Gd-1Al-0.4Zr magnesium alloy wire and Al2O3 / TiB2 ceramic powder. The steps are as follows:

[0061] Step 1: Use alcohol and an air gun to clean impurities on the surface of the Mg-15Gd-1Al-0.4Zr magnesium alloy substrate and place the substrate on a workbench; select Al2O3 and TiB2 ceramic powders with a particle size of 70 to 150 μm, and select Mg-15Gd-1Al-0.4Zr magnesium alloy wire with a diameter of 2 mm;

[0062] Step 2: Place Al2O3 ceramic powder in powder feeder 1 and adjust the powder feeding rate to 2.7 g / min. Place TiB2 ceramic powder in powder feeder 2 and adjust the powder feeding rate to 3.1 g / min. Place magnesium alloy wire in the wire feeder and set the wire feeding speed to 3000 mm / min.

[0063] Step 3: Perform silk-powder coupled arc additive manufacturing of magnesium-based composite material samples under high-purity argon powder feeding and protection, setting the arc current to 72A, the operating voltage to 20V, and the deposition rate to 280mm / min;

[0064] Step 4: After forming is completed, turn off the arc energy source, powder feeder, wire feeder, and shielding gas in sequence. Wait for the sample to cool to room temperature and use wire cutting to separate the substrate and the sample.

[0065] Comparative Example 4

[0066] The forming experiment of AZ31 magnesium alloy wire and SiO2 ceramic powder was carried out using a wire-powder coupled laser additive manufacturing system. The steps are as follows:

[0067] Step 1: Sandblast the AZ31 magnesium alloy substrate to remove the oxide scale, then use ethanol and air gun to clean the impurities on the surface and place it on the forming work platform. Select AZ31 magnesium alloy wire with a diameter of 2.4mm and SiO2 ceramic powder with a particle size of 20-70μm, place it in an electric heating vacuum drying oven at 120℃ and dry it for 6h, maintaining the vacuum degree at 10 -4 Pa;

[0068] Step 2: Place SiO2 ceramic powder in the powder feeder, place AZ31 magnesium alloy wire in the wire feeder, set the angle between the wire feeder head and the laser processing head to 47°, adjust the working distance between the bottom of the wire feeder head and the surface of the magnesium alloy substrate to 0.86 mm, set the temperature of the cooling jacket on the wire feeder tube to 25°C, and adjust the working distance between the bottom of the laser processing head and the surface of the AZ31 magnesium alloy substrate to 8 mm;

[0069] Step 3: Perform wire-powder coupled laser additive manufacturing of magnesium-based composite material samples under high-purity argon powder feeding and protection. To ensure the stability of the processing process, adjust the laser power to 453W, the scanning speed to 650mm / min, the layer height to 0.4mm, the powder feeding rate to 1.9g / min, the wire feeding speed to 900mm / min, and the oxygen content of the processing environment to 100ppm.

[0070] Result: The printing process is interrupted and the forming fails.

[0071] Comparative Example 5

[0072] The forming experiments of Mg-15Gd-1Al-0.4Zr magnesium alloy wire and TiC ceramic powder were carried out using a wire-powder coupled laser additive manufacturing system. The steps are as follows:

[0073] Step 1: The Mg-15Gd-1Al-0.4Zr magnesium alloy substrate was sandblasted to remove the oxide scale, and then the impurities on the surface were cleaned with ethanol and an air gun, and then placed on the forming work platform; Mg-15Gd-1Al-0.4Zr magnesium alloy wire with a diameter of 2.6 mm and TiC ceramic powder with a particle size of 20-70 μm were selected as the initial materials for additive manufacturing, and the TiC ceramic powder was pretreated; the pretreatment method was to place it in an electric heating vacuum drying oven at 120 ° C for 6 hours, and the vacuum degree was maintained at 10 -4 Pa;

[0074] Step 2: Place the pretreated TiC ceramic powder in the powder feeder, place the Mg-15Gd-1Al-0.4Zr magnesium alloy wire in the wire feeder, set the angle between the wire feeder head and the laser processing head to 39°, adjust the working distance between the bottom of the wire feeder head and the surface of the magnesium alloy substrate to 0.95 mm, and adjust the working distance between the bottom of the laser processing head and the surface of the Mg-15Gd-1Al-0.4Zr magnesium alloy substrate to 8 mm;

[0075] Step 3: Under high-purity argon powder feeding and protection, wire-powder coupled laser additive manufacturing of magnesium-based composite material samples was carried out according to the predetermined trajectory. To ensure the stability of the processing process, the laser power was adjusted to 445W, the scanning speed was 640mm / min, the layer height was 0.45mm, the powder feeding rate was 0.6g / min, the wire feeding speed was 600mm / min, and the oxygen content of the processing environment was 100ppm.

[0076] Step 4: After the forming is completed, turn off the laser energy source, powder feeder, wire feeder, and protective gas in sequence. After the sample cools to room temperature, use wire cutting to separate the substrate and the sample.

[0077] Performance testing:

[0078] The yield strength, tensile strength, density and ceramic content of the magnesium-based composite materials samples prepared in Examples 1 to 3 and Comparative Examples 1 to 5 were tested respectively. The test results are shown in Table 1.

[0079] Table 1

[0080] As can be seen from Table 1, the samples prepared in Examples 1 to 3 were all formed and had good mechanical properties (yield strength and tensile strength) and density.

[0081] When using starting materials of the same composition, the preparation method provided by the present invention, with its real-time cooling of the magnesium alloy wire and synchronous feeding of the ceramic powder, can ensure that the thermal reaction of the molten pool during the forming process is slowed, the sample shrinkage is uniform, and the sample forming quality is improved. However, in Comparative Example 1, which used a direct powder feeding additive manufacturing method (laser directed energy deposition, LDED), the formation of a magnesium-based composite material made of AZ91D magnesium alloy and SiC powder failed; and in Comparative Example 2, which used a powder spreading additive manufacturing method (selective laser melting, SLM), the sample formed was of poor quality.

[0082] When the same starting materials are used, the sample prepared in Comparative Example 3 using the arc additive manufacturing system has a coarse microstructure and high porosity, while the mechanical properties and density of the sample prepared by the laser additive manufacturing method in Example 3 are significantly better than those in Comparative Example 3.

[0083] When the same preparation method was used, the ceramic powder in Comparative Example 4 was replaced with SiO2 ceramic powder, but the forming process failed. This shows that only when the ceramic powder type provided by the present invention is used can a magnesium-based composite material with excellent mechanical properties be prepared.

[0084] When a wire-powder coupled laser additive manufacturing system was used to carry out forming experiments on Mg-15Gd-1Al-0.4Zr magnesium alloy wire and TiC ceramic powder, due to the lack of cooling tube cooling in Comparative Example 5, the mechanical properties of the samples prepared were poor. This shows that the cooling sleeve in the present invention controls the temperature of the magnesium alloy wire fed into the molten pool in real time, and the defects such as pores in the formed magnesium-based composite material samples are reduced (high density), and the microstructure is more refined (high yield strength).

[0085] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A laser additive manufacturing system for magnesium-based composite materials, characterized in that: The system comprises a laser regulator (1), a laser (2), a forming hood (3), an oxygen content regulator (4), an inert gas bottle (5), a powder feeder (6), a substrate (7) and a wire feeder (8); the laser regulator (1) is used to control the laser processing parameters of the laser (2); the laser (2) is connected to a laser processing head (10) via an optical fiber (9); the oxygen content regulator (4) is connected to the forming hood (3) to control the oxygen content of the processing environment in the forming hood (3); the inert gas bottle (5) and the powder feeder (6) are respectively connected to the laser processing head (10) through the forming hood (3); the substrate (7) is located in the forming hood (3); the wire feeder (8) is connected to a wire feeder head (12) via a wire feeder tube (11); the wire feeder head (12) passes through the forming hood (3) and the laser processing head (10) to perform laser additive manufacturing of magnesium-based composite materials on the substrate (7); and a real-time cooling jacket (13) is installed on the wire feeder tube (11).

2. The laser additive manufacturing system for magnesium-based composite materials according to claim 1, characterized in that: The laser is a YLS-6000-S2T fiber laser.

3. The laser additive manufacturing system for magnesium-based composite materials according to claim 1, characterized in that: The laser processing head is a YC-52 cladding head.

4. A laser additive manufacturing method for magnesium-based composite materials, characterized in that: The magnesium-based composite material is prepared by a laser additive manufacturing system according to any one of claims 1 to 3, comprising the following steps: Step 1, pre-treating the substrate; selecting magnesium alloy wire and ceramic powder as initial materials for additive manufacturing, and pre-treating the ceramic powder; Step 2: Place the pretreated ceramic powder in the powder feeder, place the magnesium alloy wire in the wire feeder, adjust the position of the wire feeder head and the laser processing head, and adjust the laser regulator to set the processing parameters of laser additive manufacturing; Step 3: Open the inert gas bottle to fill the processing environment in the molding hood with inert gas. Use the oxygen content regulator to adjust the oxygen content of the processing environment to no more than 120ppm. Start the powder feeder, wire feeder and laser The device performs additive processing on magnesium alloy wire and TiC ceramic powder according to a predetermined trajectory to manufacture magnesium-based composite formed parts that meet the requirements on the magnesium alloy substrate.

5. The laser additive manufacturing method of magnesium-based composite materials according to claim 4, characterized in that: The substrate in step 1 is a magnesium alloy substrate, and the substrate is pretreated by first sandblasting to remove the oxide scale, and then using ethanol and an air gun to clean impurities on the surface of the substrate.

6. The laser additive manufacturing method of magnesium-based composite materials according to claim 4, characterized in that: The ceramic powder in step 1 is SiC, TiC or Al2O3 / TiB2 ceramic powder. The ceramic powder is pretreated by placing it in an electrically heated vacuum drying oven with a vacuum degree maintained at 10 -4 ~10 -5 Pa, dry at 100-180℃ for 5-10h.

7. The laser additive manufacturing method of magnesium-based composite materials according to claim 4, characterized in that: The diameter of the magnesium alloy wire in step 1 is 1.2-3.5 mm, and the particle size of the ceramic powder is 20-70 μm.

8. The laser additive manufacturing method of magnesium-based composite materials according to claim 4, characterized in that: In step 1, the position is adjusted to set the angle between the wire feeding head and the laser processing head to 25-65°, adjust the working distance between the bottom of the wire feeding head and the surface of the magnesium alloy substrate to 0.5-1.5 mm, and adjust the working distance between the bottom of the laser processing head and the surface of the magnesium alloy substrate to 5-10 mm.

9. The laser additive manufacturing method of magnesium-based composite materials according to claim 4, characterized in that: The processing parameters of laser additive manufacturing in step 2 include: laser power density of 10 3 ~10 4 W / cm 2 , the scanning speed is 450-750 mm / min, the layer height is 0.3-0.6 mm, the powder feeding rate is 0.11-0.88 g / min, the wire feeding speed is 500-1000 mm / min; the temperature of the real-time cooling jacket on the wire feeding tube is 15-45°C.

10. A magnesium-based composite material, characterized in that: The magnesium-based composite material is prepared by using a laser additive manufacturing system for the magnesium-based composite material according to any one of claims 1 to 3 or by using a laser additive manufacturing method for the magnesium-based composite material according to any one of claims 4 to 9.

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