Laser protection metal matrix composite material coating and preparation method thereof

Abstract

The present invention belongs to the technical field of coating materials and provides a laser-protective metal-based composite coating and a preparation method thereof. The laser-protective metal-based composite coating comprises an aluminum substrate and Al3BC particles, wherein the Al3BC particles are distributed within the aluminum substrate; the mass ratio of the Al3BC particles to the laser-protective metal-based composite coating is 10 to 35:100. The Al3BC particles in the laser-protective metal-based composite coating are in situ self-generated, small and dispersed, exhibiting excellent strengthening effects. Furthermore, the Al3BC particles have high dimensional stability and do not coarsen with increasing temperature, which facilitates enhanced resistance to laser ablation. The in-situ self-generation of the Al3BC particles results in a clean and contamination-free interface between the Al3BC and the aluminum substrate, excellent interfacial wettability, and high interfacial bonding strength, which facilitates the enhanced resistance to laser ablation.

Description

Technical Field

[0001] The present invention relates to the technical field of coating materials, and in particular to a laser protective metal-based composite material coating and a preparation method thereof. Background Art

[0002] With the continuous advancement of laser technology, high-energy laser weapons have gradually entered the stage of practical application in the military field. In order to ensure the normal operation of weapons and equipment under laser irradiation, the research and development of laser protective materials is imperative. Laser protective coatings are the most common and effective method for laser protection of targets vulnerable to laser strikes, such as aircraft and missiles. Therefore, the research on laser protective coating materials has become a research focus in the field of laser protection. However, the current research on high-energy laser protection materials is still very insufficient, especially the research on laser protective coating materials. Most materials with obvious laser reflection effects are metal materials, but metal coatings have active chemical properties and high thermal conductivity. After being irradiated by high-energy lasers, they are easily oxidized and become ineffective. Ceramic materials generally have a high melting point and excellent thermal barrier properties, but their laser reflectivity is usually low.

[0003] Therefore, it is of great value and significance to study and obtain a metal-based composite coating with good laser reflectivity, resistance to laser ablation, and improved laser protection performance. Summary of the Invention

[0004] The purpose of the present invention is to provide a laser protective metal matrix composite material coating with excellent laser reflection performance and laser ablation resistance performance and a preparation method thereof in order to overcome the deficiencies of the prior art.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a laser protection metal matrix composite coating, which comprises an aluminum matrix and Al3BC particles, wherein the Al3BC particles are distributed in the aluminum matrix; the mass ratio of the Al3BC particles to the laser protection metal matrix composite coating is 10 to 35:100; and the Al3BC particles are in-situ generated during the spraying process.

[0007] Preferably, the particle size of the Al3BC particles is 0.06-1 μm.

[0008] Preferably, the Al3BC particles are uniformly distributed or layered in the aluminum matrix.

[0009] The present invention also provides a method for preparing the laser protective metal-based composite material coating, comprising the following steps:

[0010] 1) mixing aluminum powder, boron powder, and carbon powder, and sequentially subjecting the mixture to ball milling pretreatment, drying, and sieving to obtain a pretreated powder;

[0011] 2) spraying the pretreated powder onto a substrate material to obtain a laser protective metal matrix composite coating;

[0012] Step 2) The spraying is plasma spraying or supersonic flame spraying.

[0013] Preferably, in the mixture of step 1), the mass fraction of the boron powder is 1.0-4.6%, the mass fraction of the carbon powder is 0.8-4.1%, and the mass fraction of the aluminum powder is 91.3-98.2%.

[0014] Preferably, in the mixture, the atomic ratio of carbon to boron is 1-2:1-2.

[0015] Preferably, the boron powder comprises one or more of B4C, BN and boron powder, and the carbon powder comprises one or more of graphite powder, carbon black, graphene and carbon fiber; the particle size of the boron powder is ≤2μm, the particle size of the carbon powder is ≤2μm, and the particle size of the aluminum powder is ≤5μm.

[0016] Preferably, in the ball milling pretreatment in step 1), the ball-to-material ratio is 6 to 10:1, the rotation speed is 300 to 400 r / min, the time is 16 to 32 h, and the ball milling medium is alcohol.

[0017] Preferably, the particle size of the pretreated powder in step 1) is ≤50 μm.

[0018] Preferably, in step 2), the spraying distance is 150-250 mm, the traverse speed of the spray gun is 500-1500 mm / s, and the powder feeding rate is 4-6 r / min.

[0019] The beneficial effects of the present invention include:

[0020] 1) The laser protection metal-based composite material coating of the present invention is composed of a composite of an aluminum matrix and Al3BC particles. Al3BC has a hexagonal crystal structure, has low density, high mechanical properties and good thermal stability, and can effectively strengthen the aluminum matrix. According to the band structure of Al3BC, it has a narrow band gap (0.45eV), so it has a high dielectric constant and laser reflectivity, which can effectively reduce laser energy deposition. In addition, Al3BC particles have high thermal stability and will only undergo an endothermic transition above 1100°C, which is beneficial to the dissipation of laser energy and improves the ablation resistance of the composite material. In summary, Al3BC has a high laser reflectivity and excellent anti-laser ablation performance, and has excellent laser protection performance through the composite between Al3BC and the aluminum matrix.

[0021] 2) The Al3BC particles in the laser-protective metal-matrix composite coating of this invention are generated in situ. The size, morphology, distribution, and other microstructures of the Al3BC particles can be adjusted by adjusting the ball milling pretreatment process and the spraying process. The fine and dispersed Al3BC particles provide excellent strengthening effects. Furthermore, the Al3BC particles are highly stable and do not coarsen with increasing temperature, which improves their resistance to laser ablation. The in-situ generation of the Al3BC particles ensures a clean, contamination-free interface between the Al3BC and the aluminum substrate, resulting in excellent wettability and high interfacial bonding strength, which further enhances the laser ablation-resistant strengthening effect.

[0022] 3) The Al3BC particles in the laser protection metal-based composite coating of the present invention are uniformly or layeredly distributed, wherein the layered distribution of the Al3BC particles is beneficial to the lateral transmission of laser heat, reduces longitudinal heat transfer, reduces the temperature rise of the matrix material, and improves its laser protection performance.

[0023] 4) The method for preparing the laser protective metal-based composite material coating of the present invention is simple and suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is the microstructure of the Al3BC / Al composite coating prepared in Example 1;

[0025] Figure 2 This is a high-magnification microstructure image of the Al3BC / Al composite coating prepared in Example 1;

[0026] Figure 3 XRD pattern of the Al3BC / Al composite coating prepared in Example 1;

[0027] Figure 4 The pure aluminum coating and the composite coating with Al3BC content of 15 wt% prepared in this embodiment are at 1500 W / cm 2 Comparison of performance after laser ablation. DETAILED DESCRIPTION

[0028] The present invention provides a laser protection metal matrix composite coating, which comprises an aluminum matrix and Al3BC particles, wherein the Al3BC particles are distributed in the aluminum matrix; the mass ratio of the Al3BC particles to the laser protection metal matrix composite coating is 10 to 35:100; and the Al3BC particles are in-situ generated during the spraying process.

[0029] In the present invention, the mass ratio of the Al3BC particles to the laser protective metal matrix composite coating is preferably 15 to 30:100, more preferably 18 to 26:100, and even more preferably 20 to 23:100.

[0030] The Al3BC particle content in the laser-protective metal-based composite coating of the present invention is wide, which is conducive to selecting the appropriate Al3BC particle content for different laser energy densities. Al3BC / Al composite coatings with lower Al3BC particle content (<20wt%) have higher density and exhibit higher laser reflectivity, while also improving the composite material's resistance to laser ablation to a certain extent, and are suitable for laser densities below 1000W / cm 2 Laser irradiation; Al3BC / Al composite coatings with higher Al3BC particle content (>20wt%) have lower density. Although their laser reflectivity is reduced, they have better resistance to laser ablation. The laser density is higher than 1000W / cm 2 It shows better laser protection effect under laser irradiation.

[0031] In the present invention, the particle size of the Al3BC particles is preferably 0.06 to 1 μm, more preferably 0.1 to 0.9 μm, and even more preferably 0.3 to 0.7 μm.

[0032] In the present invention, the Al3BC particles are preferably uniformly distributed or layered distributed in the aluminum matrix.

[0033] In the present invention, the size, morphology, distribution and other microstructures of the Al3BC particles can be controlled by adjusting the size of the raw materials and the process parameters of the ball milling pretreatment.

[0034] The present invention also provides a method for preparing the laser protective metal-based composite material coating, comprising the following steps:

[0035] 1) mixing aluminum powder, boron powder, and carbon powder, and sequentially subjecting the mixture to ball milling pretreatment, drying, and sieving to obtain a pretreated powder;

[0036] 2) spraying the pretreated powder onto a substrate material to obtain a laser protective metal matrix composite coating;

[0037] Step 2) The spraying is plasma spraying or supersonic flame spraying.

[0038] In the mixture described in step 1) of the present invention, the mass fraction of boron powder is preferably 1.0-4.6%, more preferably 2.0-3.6%, and more preferably 2.5-3.0%; the mass fraction of carbonaceous powder is preferably 0.8-4.1%, more preferably 1.0-3.5%, and more preferably 1.5-3.0%; the mass fraction of aluminum powder is preferably 91.3-98.2%, more preferably 92.3-97%, and more preferably 93.3-95%.

[0039] In the mixture of the present invention, the atomic ratio of carbon to boron is preferably 1 to 2:1 to 2, more preferably 1:1.

[0040] In the present invention, by adjusting the ratio of raw materials and controlling the atomic ratio of C and B, the content of Al3BC particles can be controlled, while avoiding the 12 、Al3B 48 The generation of impurity phases such as C2.

[0041] In the present invention, the boron powder preferably comprises one or more of B4C, BN and boron powder, and the carbonaceous powder preferably comprises one or more of graphite powder, carbon black, graphene and carbon fiber; the particle size of the boron powder is preferably ≤2μm, more preferably ≤1.5μm; the particle size of the carbonaceous powder is preferably ≤2μm, more preferably ≤1.5μm; the particle size of the aluminum powder is preferably ≤5μm, more preferably ≤4μm, and more preferably ≤3μm.

[0042] In the present invention, the fine-sized raw material powder is conducive to rapid and uniform mixing during the ball milling pretreatment process and reaching a high energy state, promoting the Al3BC in-situ reaction to proceed fully in a short time, and laying the foundation for its in-situ reaction during the spraying process.

[0043] In the ball milling pretreatment in step 1) of the present invention, the ball-to-material ratio is preferably 6 to 10:1, more preferably 7 to 9:1, and more preferably 8:1; the rotation speed is preferably 300 to 400 r / min, more preferably 320 to 380 r / min, and more preferably 340 to 350 r / min; the time is preferably 16 to 32 h, more preferably 20 to 30 h, and more preferably 23 to 26 h; and the ball milling medium is preferably alcohol.

[0044] In the present invention, the mixture undergoes high-energy, long-term ball milling pretreatment to obtain a metastable pretreated powder. The ball milling pretreatment process fully mixes the raw powders, increasing the interfacial energy between the raw powders and reducing the activation energy of the in-situ reaction between the raw powders. This is key to promoting the rapid reaction of Al3BC particles during coating preparation. Adjusting the ball milling pretreatment parameters allows the size, morphology, and distribution of the Al3BC particles to be regulated. The ball milling process of the present invention can reduce the reaction activation energy. The wet milling pretreatment ensures that the raw powders reach a high-energy metastable state while preventing their size from increasing due to cold welding, which could hinder subsequent spraying.

[0045] In the present invention, the particle size of the pretreated powder in step 1) is preferably ≤50 μm, more preferably ≤45 μm.

[0046] In the present invention, the spraying distance in step 2) is preferably 150-250 mm, more preferably 170-220 mm, more preferably 190-200 mm, the traverse speed of the spray gun is preferably 500-1500 mm / s, more preferably 700-1300 mm / s, more preferably 900-1000 mm / s, the powder feeding rate is preferably 4-6 r / min, more preferably 4.5-5.5 r / min, more preferably 5 r / min; the number of spraying passes is preferably 4-10 times, more preferably 5-8 times, more preferably 6-7 times.

[0047] During the spraying process of the present invention, Al3BC particles are generated in situ, and the resulting coating has excellent laser protection effect. The coating is prepared by plasma spraying or supersonic flame spraying technology. By adjusting parameters such as spraying distance, spraying speed, powder feeding speed, and spraying passes, the coating thickness, density and other structural characteristics of the Al3BC / Al composite coating can be adjusted. The spraying process of the present invention is simple and easy to implement industrial application.

[0048] The base material of the present invention is a base material commonly used in the art, preferably an aluminum alloy, a magnesium alloy, a titanium alloy or an iron alloy.

[0049] The technical solutions provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0050] The mass concentration of ethanol in the alcohol used in the following examples is 99.5%.

[0051] Example 1

[0052] Aluminum powder (particle size 2 μm), BC powder (particle size 1.5 μm), and graphite powder (particle size 2 μm) were uniformly mixed to obtain a mixture containing 2.1 wt% BC powder, 1.2 wt% graphite powder, and the remainder aluminum powder. The mixture was ball-milled at a ball-to-material ratio of 6:1, a speed of 300 rpm, alcohol as the milling medium, and a milling time of 16 hours to obtain a metastable pretreated powder. The metastable pretreated powder was dried and sieved to obtain a pretreated powder with a particle size of 50 μm or less.

[0053] The Al3BC / Al composite material coating was prepared on the 2024 aluminum alloy substrate by using the supersonic flame spraying technology, with the sieved pretreated powder as the raw material and spraying on the 2024 aluminum alloy substrate. The spraying distance was 250 mm, the traverse speed of the spray gun was 500 mm / s, the powder feeding rate was 5 r / min, and the spraying pass was 5 times.

[0054] The Al 3 BC / Al composite coating prepared in this embodiment has an Al 3 BC particle content of 15 wt %, and the size of the Al 3 BC particles is less than 500 nm.

[0055] The microstructure of the Al3BC / Al composite coating prepared in this embodiment is as follows: Figure 1 As shown by Figure 1 It can be seen that the thickness of the Al3BC / Al composite coating is 198 μm.

[0056] The high-magnification microstructure of the Al3BC / Al composite coating prepared in this embodiment is shown in FIG. Figure 2 As shown by Figure 2 It can be seen that the composite coating is composed of aluminum and Al3BC particles, and the in-situ self-generated Al3BC particles are distributed in the aluminum matrix.

[0057] The XRD pattern of the Al3BC / Al composite coating prepared in this example is shown in FIG. Figure 3 As shown in FIG. 1 , the XRD pattern shows that the laser protection composite coating of this embodiment is composed of Al and Al3BC.

[0058] The pure aluminum coating and the composite coating with Al3BC content of 15 wt% prepared in this embodiment were 2 Comparison of performance after laser ablation Figure 4 As shown, the 15% Al3BC / Al coating is a composite coating with an Al3BC content of 15 wt% in Example 1. Figure 4 It can be seen that the pure aluminum coating was broken down after 5s of ablation, while the Al3BC / Al composite coating was broken down after 10s of ablation, which confirms that the Al3BC / Al composite coating has better resistance to laser ablation than the pure aluminum coating.

[0059] Example 2

[0060] Aluminum powder (particle size 2 μm), BC powder (particle size 1.5 μm), and graphite powder (particle size 2 μm) were uniformly mixed to obtain a mixture containing 4.6 wt% BC powder, 3.0 wt% graphite powder, and the remainder aluminum powder. The mixture was ball-milled at a ball-to-concentrate ratio of 6:1, a speed of 400 rpm, alcohol as the milling medium, and a milling time of 32 hours to obtain a metastable pretreated powder. The metastable pretreated powder was dried and sieved to obtain a pretreated powder with a particle size of 50 μm or less.

[0061] The Al3BC / Al composite material coating was prepared on the 6061 aluminum alloy substrate by using the supersonic flame spraying technology with the sieved pretreated powder as the raw material. The spraying distance was 200 mm, the traverse speed of the spray gun was 1000 mm / s, the powder feeding rate was 6 r / min, and the spraying pass was 5 times.

[0062] The thickness of the Al 3 BC / Al composite material coating prepared in this embodiment is 125 μm, the content of Al 3 BC particles in the coating is 35 wt %, and the size of the Al 3 BC particles is less than 1 μm.

[0063] Example 3

[0064] Aluminum powder (5 μm particle size), BC powder (1.5 μm particle size), and carbon black powder (2 μm particle size) were uniformly mixed to obtain a mixture containing 3.3 wt% BC powder, 2.2 wt% carbon black powder, and the remainder aluminum powder. The mixture was ball-milled at a ball-to-material ratio of 10:1, a speed of 350 rpm, alcohol as the milling medium, and a milling time of 24 hours to obtain a metastable pretreated powder. The metastable pretreated powder was dried and sieved to obtain a pretreated powder with a particle size of 50 μm or less.

[0065] The Al3BC / Al composite material coating was prepared on the AZ91 magnesium alloy substrate by using the supersonic flame spraying technology, with the sieved pretreated powder as the raw material and spraying on the AZ91 magnesium alloy substrate. The spraying distance was 250 mm, the traverse speed of the spray gun was 1000 mm / s, the powder feeding rate was 5 r / min, and the spraying pass was 8 times.

[0066] The thickness of the Al 3 BC / Al composite coating prepared in this embodiment is 160 μm, the content of Al 3 BC particles in the coating is 25 wt %, and the size of the Al 3 BC particles is less than 500 nm.

[0067] Example 4

[0068] Aluminum powder (5 μm particle size), boron powder (1 μm particle size), and carbon fiber (2 μm length) were uniformly mixed to a mixture containing 3.2 wt% boron powder, 3.4 wt% carbon fiber, and the remainder aluminum powder. The mixture was ball-milled at a ball-to-material ratio of 7:1, a speed of 400 rpm, alcohol as the milling medium, and a milling time of 24 hours to obtain a metastable pretreated powder. The metastable pretreated powder was dried and sieved to obtain a pretreated powder with a particle size of 50 μm or less.

[0069] The Al3BC / Al composite material coating was prepared on the stainless steel substrate by using the supersonic flame spraying technology with the sieved pretreated powder as the raw material. The spraying distance was 150 mm, the traverse speed of the spray gun was 1500 mm / s, the powder feeding rate was 4 r / min, and the spraying pass was 5 times.

[0070] The thickness of the Al 3 BC / Al composite material coating prepared in this embodiment is 80 μm, the content of Al 3 BC particles in the coating is 30 wt %, and the size of the Al 3 BC particles is less than 1 μm.

[0071] Example 5

[0072] Aluminum powder (5 μm particle size), boron powder (1 μm particle size), and graphite powder (2 μm particle size) were uniformly mixed to a boron powder content of 1.0 wt%, a graphite powder content of 1.2 wt%, and the remainder being aluminum powder. The mixture was ball-milled at a ball-to-concentrate ratio of 7:1, a speed of 300 rpm, alcohol as the milling medium, and a milling time of 16 hours to obtain a metastable pretreated powder. The metastable pretreated powder was dried and sieved to obtain a pretreated powder with a particle size of 50 μm or less.

[0073] The Al3BC / Al composite coating was prepared on the 7050 aluminum alloy substrate by using the supersonic flame spraying technology with the sieved pretreated powder as the raw material. The spraying distance was 150 mm, the spray gun traverse speed was 500 mm / s, the powder feed rate was 4 r / min, and the spraying pass was 5 times.

[0074] The thickness of the Al 3 BC / Al composite coating prepared in this embodiment is 155 μm, the content of Al 3 BC particles in the coating is 10 wt %, and the size of the Al 3 BC particles is less than 500 nm.

[0075] Example 6

[0076] Aluminum powder (5 μm particle size), boron powder (1 μm particle size), and graphite powder (2 μm particle size) were uniformly mixed to a mixture containing 3.6 wt% boron powder, 4.1 wt% graphite powder, and the remainder aluminum powder. The mixture was ball-milled at a ball-to-concentrate ratio of 6:1, a speed of 360 rpm, alcohol as the milling medium, and a milling time of 32 hours to obtain a metastable pretreated powder. The metastable pretreated powder was dried and sieved to obtain a pretreated powder with a particle size of 50 μm or less.

[0077] Using supersonic flame spraying technology, the screened pretreated powder was used as raw material to spray on the TC4 titanium alloy substrate. The spraying distance was 200 mm, the traverse speed of the spray gun was 1000 mm / s, the powder feed rate was 6 r / min, and the spraying pass was 5 times. Al3BC / Al composite material coating was prepared on the TC4 titanium alloy substrate.

[0078] The thickness of the Al 3 BC / Al composite coating prepared in this embodiment is 120 μm, the content of Al 3 BC particles in the coating is 35 wt %, and the size of the Al 3 BC particles is less than 1 μm.

[0079] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing a laser protective metal matrix composite coating, characterized in that: The laser protection metal matrix composite coating comprises an aluminum matrix and Al3BC particles, wherein the Al3BC particles are distributed in the aluminum matrix; the mass ratio of the Al3BC particles to the laser protection metal matrix composite coating is 10-35:100; and the Al3BC particles are in-situ generated during the spraying process; The method for preparing the laser protective metal matrix composite material coating comprises the following steps: 1) Aluminum powder, boron powder, and carbon powder are mixed, and the mixture is subjected to ball milling pretreatment, drying, and sieving in sequence to obtain a pretreated powder; 2) spraying the pretreated powder onto a substrate material to obtain a laser protective metal matrix composite coating; Step 2) the spraying is plasma spraying or supersonic flame spraying; Step 2) The spraying distance is 150-250 mm, the spray gun traverse speed is 500-1500 mm / s, and the powder feeding rate is 4-6 r / min.

2. The preparation method according to claim 1, characterized in that The particle size of the Al3BC particles is 0.06-1 μm.

3. The preparation method according to claim 1 or 2, characterized in that Al3BC particles are evenly distributed or layered in the aluminum matrix.

4. The preparation method according to claim 3, characterized in that In step 1), the mass fraction of the boron powder in the mixture is 1.0-4.6%, the mass fraction of the carbon powder is 0.8-4.1%, and the mass fraction of the aluminum powder is 91.3-98.2%.

5. The preparation method according to claim 4, characterized in that In the mixture, the atomic ratio of carbon to boron is 1~2:1~2.

6. The preparation method according to claim 5, characterized in that The boron powder includes one or more of B4C, BN and boron powder, and the carbon powder includes one or more of graphite powder, carbon black, graphene and carbon fiber; the particle size of the boron powder is ≤2μm, the particle size of the carbon powder is ≤2μm, and the particle size of the aluminum powder is ≤5μm.

7. The preparation method according to claim 6, characterized in that In step 1), the ball-to-material ratio is 6-10:1, the rotation speed is 300-400 r / min, the time is 16-32 h, and the ball milling medium is alcohol.

8. The preparation method according to claim 7, characterized in that Step 1) The particle size of the pretreated powder is ≤50 μm.

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