A laser directed energy deposition method for large-size Al2O3-based ceramic structural parts

Abstract

The present invention discloses a laser directed energy deposition method for producing large-scale Al2O3-based ceramic components. The method comprises the following steps: Step 1: Heat-treating aluminum alloy powder and Al2O3 ceramic powder, mixing them uniformly, and then placing them in a powder feeder; Step 2: To ensure that the aluminum alloy powder is fully melted while the Al2O3 ceramic powder remains unmelted during the laser forming process, the laser forming process parameters are set: laser power of 150-500W, scanning speed of 250-1000mm / min, powder feeding rate of 1.5-8.5g / min, spot diameter of 1.5-6mm, and the oxygen content of the forming environment is adjusted to no more than 200ppm; Step 3: Activating an inert gas supply to provide powder feeding power and protective gas for the forming process, starting the powder feeder and laser, and performing the forming process. The present invention prepares large-scale Al2O3-based ceramic components with high fracture toughness and good density by doping Al2O3 powder with aluminum alloy, limiting the ratio of Al2O3 powder to aluminum alloy powder, and adjusting the parameters during the laser directed energy deposition process.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic materials, and in particular to a laser directed energy deposition method for aluminum alloy consolidation of large-sized Al2O3-based ceramic structural parts. Background Art

[0002] Ceramic materials have high thermal, mechanical, and chemical stability and are widely used in aerospace, energy and chemical, automotive, marine engineering, and nuclear power industries. For example, they are used to manufacture hot end components of aircraft engines and gas turbines, spacecraft thermal insulation layers, automotive brake pads, corrosion-resistant sensors, and nuclear reactor components. Existing ceramic preparation methods generally use a method of forming first and then sintering at high temperatures, mainly including slip casting sintering, hot pressing sintering, and sol-gel sintering. However, there are still many disadvantages when using these methods to prepare high-performance ceramics, mainly reflected in: (1) long cycle time; (2) low efficiency; and (3) difficulty in forming complex shapes.

[0003] Laser Directed Energy Deposition (LDED), also known as Laser Near-Net Shape (LENS™), is a high-end digital manufacturing technology that uses a laser beam to coaxially melt powder to form parts directly onto a substrate. This technology, characterized by localized deposition and layer-by-layer accumulation, enables the rapid and high-precision manufacture of high-performance parts with complex three-dimensional structures, significantly shortening fabrication cycles and significantly improving production efficiency. Therefore, this technology holds great potential for achieving the integrated "forming-sintering" process for ceramic fabrication.

[0004] During the laser directed energy deposition (DEL) process of Al2O3-based ceramic components, high temperature gradients and one-dimensional heat dissipation ensure single-crystal microstructure growth, resulting in high density and the full utilization of the excellent properties of Al2O3 ceramic materials. However, the high temperature gradients, high cooling rates, and extreme cold contraction inherent in the high-energy laser DEL process induce forming defects within the inherently hard and brittle ceramic, affecting forming quality and limiting the direct laser forming of large-section Al2O3-based ceramic components.

[0005] In response to the above problems, relevant researchers have proposed that the problems can be improved by adjusting process parameters, ultrasonic assistance, preheating assistance and other methods. For example, American scholars Yingbin Hu, Weilong Cong: "Ultrasonic vibration-assisted laser engineering net shaping of ZrO2-Al2O3 bulk parts: effects on crack suppression, microstructure and mechanical properties", "Ceramics International", Vol. 44, 2018; Indian scholar Govind Kumar Mishra: "Ultrasonic vibration-assisted laser net shaping of ZrO2-Al2O3 bulk parts: effects on crack suppression, microstructure and mechanical properties (Experimental investigation on Laser Directed Energy Deposition based additive manufacturing of Al2O3 bulk structures)", "Ceramics International", Vol. 47, 2021.

[0006] However, although literature reports indicate that optimizing process parameters can be used to reduce defects such as porosity and microcracks to form large-section ceramic structures, the narrow process window for forming crack-free structures and the interdependence between key parameters significantly limit the effectiveness of this technology. Furthermore, research results indicate that while applying ultrasound to the laser deposition process can reduce forming stress, improve density, and achieve grain refinement, the ultrasonic effect decays as the height of the structure increases. Summary of the Invention

[0007] In view of this, the present invention aims to provide a laser directed energy deposition method for large-scale Al2O3-based ceramic structural components. By consolidating aluminum alloys, the forming quality is improved, and large-scale Al2O3-based ceramic structural components with high fracture toughness and good density are produced.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a laser directed energy deposition method for a large-sized Al2O3-based ceramic structural component, comprising the following steps:

[0010] Step 1: Heat-treating aluminum alloy powder and Al2O3 ceramic powder, mixing them evenly, and then placing them in a powder feeder;

[0011] Step 2: To ensure that the aluminum alloy powder is fully melted and the Al2O3 ceramic powder is not melted during the laser forming process, the laser forming process parameters are set as follows: laser power is 150-500W, scanning speed is 250-1000mm / min, powder feeding rate is 1.5-8.5g / min, spot diameter is 1.5-6mm, and the oxygen content of the forming environment is adjusted to no more than 200ppm;

[0012] Step 3: Turn on the inert gas to provide powder feeding power and protective gas for the forming process, start the powder feeder and laser, and perform the forming process.

[0013] Furthermore, the particle size of the aluminum alloy powder and the Al2O3 ceramic powder in step 1 is 20 to 60 μm.

[0014] Furthermore, the aluminum alloy powder in step 1 includes AlSi 10 One or more of Mg aluminum alloy powder, 2024 aluminum alloy, 6061 aluminum alloy, 6063 aluminum alloy, 7075 aluminum alloy, and 5083 aluminum alloy.

[0015] Furthermore, in step 1, the aluminum alloy powder accounts for 8 to 35 wt % of the total powder content, which is the total weight of the aluminum alloy powder and the Al 2 O 3 ceramic powder.

[0016] Furthermore, the heat treatment in step 1 is carried out by drying at 100-200° C. for 4-12 hours in an electrically heated heat treatment furnace.

[0017] Furthermore, the mixing method in step 1 is to use a plasma ball milling process to achieve uniform mixing of the powders in a vacuum environment, and the vacuum degree is 10 -5 ~10 -3 Pa.

[0018] Furthermore, the inert gas in step 3 includes argon, nitrogen or helium with a purity of 99.99%.

[0019] In a second aspect, the present invention provides a large-sized Al2O3-based ceramic structural component, which is prepared by the laser directed energy deposition method of the above-mentioned large-sized Al2O3-based ceramic structural component.

[0020] The beneficial effects of the present invention are:

[0021] This invention provides a laser directed energy deposition method for producing large-scale Al2O3-based ceramic components. By doping Al2O3 powder with an aluminum alloy, controlling the ratio of Al2O3 powder to aluminum alloy powder, and adjusting parameters during the laser directed energy deposition process, large-scale Al2O3-based ceramic components with high fracture toughness and good density are produced. Furthermore, the deposition method is simple and easy to operate, with low production costs, making it suitable for industrial mass production.

[0022] Figures in the specification

[0023] Figure 1 This is a physical picture of the large-sized Al2O3-based ceramic structural component of the present invention. DETAILED DESCRIPTION

[0024] 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.

[0025] 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.

[0026] Example 1

[0027] A laser directed energy deposition method for large-sized Al2O3-based ceramic structural parts comprises the following steps:

[0028] Step 1: AlSi with a particle size of 20 to 60 μm 10 Mg aluminum alloy powder and Al2O3 ceramic powder are heat treated, wherein AlSi 10 The mass ratio of Mg aluminum alloy powder to the total powder content is 8.5wt%; the heat treatment method is to dry it in an electric heating heat treatment furnace at 100℃ for 4h; the heat-treated powder is uniformly mixed in a vacuum environment using a plasma ball milling process, and the vacuum degree is 10 -5 Pa; the evenly mixed powder is placed in a powder feeder;

[0029] Step 2: To ensure AlSi 10The Mg aluminum alloy powder was fully melted, and the Al2O3 ceramic powder was not melted. The laser forming process parameters were set as follows: laser power of 150W, scanning speed of 250mm / min, powder feeding rate of 1.5g / min, spot diameter of 1.5mm, and oxygen content of the forming environment was adjusted to 100ppm.

[0030] Step 3: Turn on the inert gas to provide powder feeding power and protective gas for the forming process, start the powder feeder and laser, and perform the forming process.

[0031] The prepared physical picture is as follows Figure 1 As shown, the size is 25mm×25mm×4mm. Figure 1 It can be seen that the cross-sectional size of the formed part without surface cracks can reach 25 mm.

[0032] Example 2

[0033] A laser directed energy deposition method for large-sized Al2O3-based ceramic structural parts comprises the following steps:

[0034] Step 1: heat-treating 2024 aluminum alloy powder with a particle size of 20 to 60 μm and Al2O3 ceramic powder, wherein the mass ratio of the aluminum alloy powder to the total powder content is 15.8 wt%; the heat treatment method is to dry the powder at 100 ° C for 4 hours in an electric heating heat treatment furnace; the heat-treated powder is uniformly mixed by a plasma ball milling process in a vacuum environment, and the vacuum degree is 10 -4 Pa; the evenly mixed powder is placed in a powder feeder;

[0035] Step 2: To ensure that the aluminum alloy powder is fully melted and the Al2O3 ceramic powder is not melted during the laser forming process, the laser forming process parameters are set as follows: laser power is 350W, scanning speed is 650mm / min, powder feeding rate is 5.5g / min, spot diameter is 3.5mm, and the oxygen content of the forming environment is adjusted to 150ppm;

[0036] Step 3: Turn on the inert gas to provide powder feeding power and protective gas for the forming process, start the powder feeder and laser, and perform the forming process.

[0037] The size of the prepared formed structural part is 30 mm × 30 mm × 10 mm.

[0038] Example 3

[0039] A laser directed energy deposition method for large-sized Al2O3-based ceramic structural parts comprises the following steps:

[0040] Step 1: heat-treating 6061 aluminum alloy powder with a particle size of 20 to 60 μm and Al2O3 ceramic powder, wherein the mass ratio of 6061 aluminum alloy powder to the total powder content is 24.2 wt%; the heat treatment method is to dry it in an electric heating heat treatment furnace at 100°C for 4 hours; the heat-treated powder is uniformly mixed by a plasma ball milling process in a vacuum environment, and the vacuum degree is 10 -3 Pa; the evenly mixed powder is placed in a powder feeder;

[0041] Step 2: To ensure that the 6061 aluminum alloy powder is fully melted and the Al2O3 ceramic powder is not melted during the laser forming process, the laser forming process parameters are set as follows: laser power is 500 W, scanning speed is 1000 mm / min, powder feeding rate is 8.5 g / min, spot diameter is 6 mm, and the oxygen content of the forming environment is adjusted to 200 ppm.

[0042] Step 3: Turn on the inert gas to provide powder feeding power and protective gas for the forming process, start the powder feeder and laser, and perform the forming process.

[0043] The size of the prepared formed structural part is 40 mm × 40 mm × 15 mm.

[0044] Comparative Example 1

[0045] A laser directed energy deposition method for large-sized Al2O3-based ceramic structural parts comprises the following steps:

[0046] Step 1: heat-treating Inconel 625 alloy powder with a particle size of 20 to 60 μm and Al2O3 ceramic powder, wherein the mass ratio of Inconel 625 alloy powder to the total powder content is 8.5 wt%; the heat treatment method is to dry the powder at 100 ° C in an electric heating heat treatment furnace for 4 hours; the heat-treated powder is uniformly mixed in a vacuum environment by a plasma ball milling process, and the vacuum degree is 10 -5 Pa; the evenly mixed powder is placed in a powder feeder;

[0047] Step 2: Set the laser forming process parameters: laser power is 150W, scanning speed is 250mm / min, powder feeding rate is 1.5g / min, spot diameter is 1.5mm, and the oxygen content of the forming environment is adjusted to 100ppm;

[0048] Step 3: Turn on the inert gas to provide powder feeding power and protective gas for the forming process, start the powder feeder and laser, and perform the forming process; the planned printing size is 25mm×25mm×4mm.

[0049] Result: The printing process is interrupted and the forming fails.

[0050] Comparative Example 2

[0051] A laser directed energy deposition method for large-sized Al2O3-based ceramic structural parts comprises the following steps:

[0052] Step 1: heat-treating 304 stainless steel powder with a particle size of 20 to 60 μm and Al2O3 ceramic powder, wherein the mass ratio of 304 stainless steel powder to the total powder content is 15.8 wt%; the heat treatment method is to dry it in an electric heating heat treatment furnace at 100°C for 4 hours; the heat-treated powder is uniformly mixed by a plasma ball milling process in a vacuum environment, and the vacuum degree is 10 -4 Pa; the evenly mixed powder is placed in a powder feeder;

[0053] Step 2: Set the laser forming process parameters: laser power is 350W, scanning speed is 650mm / min, powder feeding rate is 5.5g / min, spot diameter is 3.5mm, and the oxygen content of the forming environment is adjusted to 150ppm;

[0054] Step 3: Turn on the inert gas to provide powder feeding power and protective gas for the forming process, start the powder feeder and laser, and perform the forming process; the planned printing size is 30mm×30mm×10mm.

[0055] Result: The printing process is interrupted and the forming fails.

[0056] Comparative Example 3

[0057] A laser directed energy deposition method for large-sized Al2O3-based ceramic structural parts comprises the following steps:

[0058] Step 1: AlSi with a particle size of 20 to 60 μm 10 Mg aluminum alloy powder and Al2O3 ceramic powder are heat treated, wherein AlSi 10 The mass ratio of Mg aluminum alloy powder to the total powder content is 7wt%; the heat treatment method is to dry it in an electric heating heat treatment furnace at 100℃ for 4h; the heat-treated powder is uniformly mixed in a vacuum environment using a plasma ball milling process, and the vacuum degree is 10 -6 Pa; the evenly mixed powder is placed in a powder feeder;

[0059] Step 2: To ensure AlSi 10 The Mg aluminum alloy powder was fully melted, and the Al2O3 ceramic powder was not melted. The laser forming process parameters were set as follows: laser power of 150W, scanning speed of 250mm / min, powder feeding rate of 1.5g / min, spot diameter of 1.5mm, and oxygen content of the forming environment was adjusted to 100ppm.

[0060] Step 3: Turn on the inert gas to provide powder feeding power and protective gas for the forming process, start the powder feeder and laser, and perform the forming process; the planned printing size is 25mm×25mm×4mm.

[0061] Result: The printing process is interrupted and the forming fails.

[0062] Comparative Example 4

[0063] A laser directed energy deposition method for large-sized Al2O3-based ceramic structural parts comprises the following steps:

[0064] Step 1: heat-treating 2024 aluminum alloy powder with a particle size of 20 to 60 μm and Al2O3 ceramic powder, wherein the mass ratio of 2024 aluminum alloy powder to the total powder content is 45.5 wt%; the heat treatment method is to dry it at 100 ° C for 4 hours in an electric heating heat treatment furnace; the heat-treated powder is uniformly mixed by a plasma ball milling process in a vacuum environment, and the vacuum degree is 10 -2 Pa; the evenly mixed powder is placed in a powder feeder;

[0065] Step 2: To ensure that the 2024 aluminum alloy powder is fully melted and the Al2O3 ceramic powder is not melted during the laser forming process, the laser forming process parameters are set as follows: laser power is 600 W, scanning speed is 150 mm / min, powder feeding rate is 1.4 g / min, spot diameter is 1.3 mm, and the oxygen content of the forming environment is adjusted to 350 ppm.

[0066] Step 3: Turn on the inert gas to provide powder feeding power and shielding gas for the forming process. Start the powder feeder and laser to start the forming process. The planned printing size is 30mm × 30mm × 10mm.

[0067] Result: The printing process is interrupted and the forming fails.

[0068] Comparative Example 5

[0069] A laser directed energy deposition method for large-sized Al2O3-based ceramic structural parts comprises the following steps:

[0070] Step 1: heat-treating 6061 aluminum alloy powder with a particle size of 20 to 60 μm and Al2O3 ceramic powder, wherein the mass ratio of 6061 aluminum alloy powder to the total powder content is 24.2 wt%; the heat treatment method is to dry it at 100°C in an electric heating heat treatment furnace for 4 hours; the heat-treated powder is uniformly mixed by a plasma ball milling process in a vacuum environment, and the vacuum degree is 10 -3 Pa; the evenly mixed powder is placed in a powder feeder;

[0071] Step 2: To ensure that the 6061 aluminum alloy powder is fully melted and the Al2O3 ceramic powder is not melted during the laser forming process, the laser forming process parameters are set as follows: laser power is 100 W, scanning speed is 1200 mm / min, powder feeding rate is 9.5 g / min, spot diameter is 7 mm, and the oxygen content of the forming environment is adjusted to 150 ppm.

[0072] Step 3: Turn on the inert gas to provide powder feeding power and protective gas for the forming process, start the powder feeder and laser, and perform the forming process.

[0073] The size of the prepared formed structural part is 40 mm × 40 mm × 15 mm.

[0074] Performance testing:

[0075] The fracture toughness and density of the large-sized Al2O3-based ceramic structural components prepared in Examples 1 to 3 and Comparative Examples 1 to 5 were tested respectively. The test results are shown in Table 1.

[0076] Table 1

[0077]

[0078]

[0079] As can be seen from Table 1, the laser directed energy deposition method for preparing large-sized Al2O3-based ceramic structural parts using the deposition method provided by the present invention, that is, the use of aluminum alloy powder for consolidation, can produce formed structural parts with high fracture toughness and good density (Examples 1-3); when the same preparation method is used and other alloys are used for consolidation, such as 304 stainless steel powder, Inconel 625 alloy powder, etc., no formed structural parts can be produced; when the aluminum alloy powder consolidation method is also used, but the deposition process parameters are not within the scope of the present invention, the forming fails or the structural performance of the prepared formed parts is poor.

[0080] 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 directed energy deposition method for large-sized Al2O3-based ceramic structural parts, characterized in that: The following steps are involved: Step 1: Heat-treating aluminum alloy powder and Al2O3 ceramic powder and then mixing them uniformly. The mixing method is to use a plasma ball milling process to achieve uniform mixing of the powders in a vacuum environment; and then placing them in a powder feeder; Step 2: To ensure that the aluminum alloy powder is fully melted and the Al2O3 ceramic powder is not melted during the laser forming process, the laser forming process parameters are set as follows: laser power is 150-500W, scanning speed is 250-1000mm / min, powder feeding rate is 1.5-8.5g / min, spot diameter is 1.5-6mm, and the oxygen content of the forming environment is adjusted to no more than 200ppm; Step 3: Turn on the inert gas to provide powder feeding power and protective gas for the forming process, start the powder feeder and laser, and perform the forming process.

2. The laser directed energy deposition method for large-sized Al2O3-based ceramic structural parts according to claim 1, characterized in that: The particle size of the aluminum alloy powder and the Al2O3 ceramic powder in step 1 is 20 to 60 μm.

3. The laser directed energy deposition method for large-sized Al2O3-based ceramic structural parts according to claim 1, characterized in that: The aluminum alloy powder in step 1 includes AlSi 10 One or more of Mg aluminum alloy powder, 2024 aluminum alloy, 6061 aluminum alloy, 6063 aluminum alloy, 7075 aluminum alloy, and 5083 aluminum alloy.

4. The laser directed energy deposition method for large-sized Al2O3-based ceramic structural parts according to claim 1, characterized in that: In step 1, the aluminum alloy powder accounts for 8 to 35 wt % of the total powder content.

5. The laser directed energy deposition method for large-sized Al2O3-based ceramic structural parts according to claim 1, characterized in that: The heat treatment method in step 1 is to dry the product at 100-200° C. for 4-12 hours in an electric heating heat treatment furnace.

6. The laser directed energy deposition method for large-sized Al2O3-based ceramic structural parts according to claim 1, characterized in that: The vacuum degree in step 1 is 10 -5 ~10 -3 Pa.

7. The laser directed energy deposition method for large-sized Al2O3-based ceramic structural parts according to claim 1, characterized in that: In step 3, the inert gas includes argon, nitrogen or helium with a purity of 99.99%.

8. A large-sized Al2O3-based ceramic structural component, characterized in that: The large-sized Al2O3-based ceramic structural component is prepared by the laser directed energy deposition method according to any one of claims 1 to 7.

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