Aluminum-nanometer aluminum oxide composite powder and preparation method thereof, and preparation method of aluminum-nanometer aluminum oxide composite coating

Abstract

The invention relates to the technical field of preparation of aluminum-based composite coatings, in particular to aluminum-nanometer aluminum oxide composite powder, a preparation method of the aluminum-nanometer aluminum oxide composite powder and a preparation method of an aluminum-nanometer aluminum oxide composite coating. The aluminum-nanometer aluminum oxide composite powder comprises nanometer aluminum oxide and aluminum wrapping the surface of the nanometer aluminum oxide. According to the preparation method, aluminum is used for wrapping nanometer aluminum oxide particles, that is, the nanometer aluminum oxide particles are distributed in aluminum particles, aluminum-nanometer aluminum oxide composite powder serves as spraying powder, and in the process of preparing the aluminum-nanometer aluminum oxide composite coating through a cold spraying method, the composite powder can generate plastic deformation to form the composite coating; due to the fact that the nanometer aluminum oxide is distributed in the aluminum particles, the nanometer aluminum oxide can be deposited in the composite coating at the same time in the process that the aluminum is subjected to plastic deformation to form the coating, compared with aluminum oxide and aluminum which are deposited separately, the nanometer aluminum oxide in the composite coating is high in content and even in distribution, and the hardness and the abrasion resistance of the composite coating are improved.

Description

Technical Field

[0001] The invention relates to the technical field of aluminum-based composite coating preparation, and in particular to an aluminum-nano alumina composite powder and a preparation method thereof, and a preparation method of an aluminum-nano alumina composite coating. Background Art

[0002] Aluminum alloy has a low density, and aluminum alloy parts are widely used in the field of aircraft manufacturing. Due to the low hardness of aluminum alloy, aluminum alloy parts are easily worn during use, resulting in part failure. It is of great significance to improve the hardness and wear resistance of the aluminum alloy surface.

[0003] In the aluminum-alumina composite coating, the aluminum oxide particles are dispersed in the aluminum matrix. The aluminum oxide particles have high hardness, and the aluminum oxide strengthening phase improves the hardness and wear resistance of the composite material. Preparing an aluminum-alumina composite coating on the surface of an aluminum alloy can improve the hardness and wear resistance of the surface of aluminum alloy parts.

[0004] Cold spraying is a method for preparing aluminum-aluminum oxide composite coatings. The common cold spraying method uses a mixed powder of aluminum and aluminum oxide for cold spraying. Aluminum powder has high plasticity and is easy to deform plastically to form an aluminum coating. However, aluminum oxide powder has low plasticity and is difficult to form a coating through plastic deformation. As a result, the aluminum oxide content in the aluminum-aluminum oxide composite coating is low (the mass fraction is generally less than 10%) and the distribution is uneven, resulting in low hardness and wear resistance of the aluminum-aluminum oxide composite coating. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide an aluminum-nano alumina composite powder and a preparation method thereof, and a preparation method of an aluminum-nano alumina composite coating. The present invention uses the aluminum-nano alumina composite powder as a spray powder to prepare an aluminum-nano alumina composite coating, the content of nano alumina in the composite coating is high and evenly distributed, and the hardness and wear resistance of the composite coating are high.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The invention provides an aluminum-nano aluminum oxide composite powder, comprising nano aluminum oxide and aluminum wrapped on the surface of the nano aluminum oxide.

[0008] Preferably, the mass fraction of nano-alumina in the aluminum-nano-alumina composite powder is 30-40%.

[0009] Preferably, the particle size of the aluminum-nano-alumina composite powder is 15 to 45 μm, and the particle size of the nano-alumina is 50 to 100 nm.

[0010] The present invention provides a method for preparing the aluminum-nano alumina composite powder described in the above scheme, comprising the following steps:

[0011] Ball milling aluminum powder and nano-alumina to obtain mixed powder;

[0012] The mixed powder is smelted at a temperature greater than the melting point of aluminum and lower than the melting point of aluminum oxide, so that the nano-alumina particles are dispersed in the aluminum liquid to obtain a mixed liquid;

[0013] The mixed liquid is atomized to obtain the aluminum-nano alumina composite powder.

[0014] Preferably, the particle size of the aluminum powder is 0.5 to 1.5 μm; the particle size of the nano-alumina is 50 to 100 nm.

[0015] Preferably, the mass fraction of nano-alumina in the mixed powder is 30-40%.

[0016] Preferably, the speed of the ball mill is 140 to 180 r / min. -1 , time is 5 to 7 hours.

[0017] Preferably, the atomization air pressure is 2.8-3.2 MPa.

[0018] The present invention provides a method for preparing an aluminum-nano aluminum oxide composite coating, comprising the following steps: spraying aluminum-nano aluminum oxide composite powder onto a substrate surface by a cold spraying method to form an aluminum-nano aluminum oxide composite coating on the substrate surface;

[0019] The aluminum-nano alumina composite powder is the aluminum-nano alumina composite powder described in the above scheme or the aluminum-nano alumina composite powder prepared by the preparation method described in the above scheme.

[0020] Preferably, the spraying air pressure is 5.3-5.7 MPa, the spraying distance is 28-32 mm, and the powder feeding rate is 1-2 rpm.

[0021] The present invention provides an aluminum-nano alumina composite powder, comprising nano alumina and aluminum wrapped on the surface of the nano alumina. The present invention wraps nano alumina particles with aluminum, that is, the nano alumina particles are distributed in the aluminum particles, and the aluminum-nano alumina composite powder is used as the spray powder. In the process of preparing the aluminum-nano alumina composite coating by cold spraying, the composite powder undergoes plastic deformation to form a composite coating. Since the nano alumina is distributed in the aluminum particles, the aluminum undergoes plastic deformation to form the coating, and the nano alumina is simultaneously deposited in the composite coating. Compared with separately depositing aluminum oxide and aluminum, the content of nano alumina in the composite coating is high (reaching 28-36%) and evenly distributed, and the hardness and wear resistance of the composite coating are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a cross-sectional SEM image of the aluminum-nano-aluminum oxide composite coating prepared in Example 1.

[0023] Figure 2 This is a cross-sectional SEM image of the aluminum-nano-aluminum oxide composite coating prepared in Comparative Example 1. DETAILED DESCRIPTION

[0024] The invention provides an aluminum-nano aluminum oxide composite powder, comprising nano aluminum oxide and aluminum wrapped on the surface of the nano aluminum oxide.

[0025] In the present invention, the mass fraction of nano-alumina in the aluminum-nano-alumina composite powder is preferably 30-40%, and in specific embodiments may be 30%, 32%, 35%, 38% or 40%.

[0026] In the present invention, the particle size of the aluminum-nano alumina composite powder is preferably 15 to 45 μm, and in specific embodiments may be 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm or 45 μm; the particle size of the nano alumina is preferably 50 to 100 nm, and in specific embodiments may be 50 nm, 60 nm, 70 nm, 80 nm, 90 nm or 100 nm.

[0027] The present invention provides a method for preparing the aluminum-nano-alumina composite powder of the above scheme, comprising the following steps: ball-milling aluminum powder and nano-alumina to obtain a mixed powder;

[0028] The mixed powder is smelted at a temperature greater than the melting point of aluminum and lower than the melting point of aluminum oxide, so that the nano-alumina particles are dispersed in the aluminum liquid to obtain a mixed liquid;

[0029] The mixed liquid is atomized to obtain the aluminum-nano alumina composite powder.

[0030] In the present invention, unless otherwise specified, the raw materials used are commercially available products well known in the art.

[0031] The invention ball-mills aluminum powder and nano aluminum oxide to obtain mixed powder.

[0032] In the present invention, the particle size of the aluminum powder is preferably 0.5-1.5 μm, and in a specific embodiment can be 0.5 μm, 1.0 μm or 1.5 μm; the particle size of the nano alumina is preferably 50-100 nm, and in a specific embodiment can be 50 nm, 60 nm, 70 nm, 80 nm, 90 nm or 100 nm.

[0033] In the present invention, the amount of the aluminum powder and nano-alumina is preferably such that the mass fraction of nano-alumina in the mixed powder is 30-40%, and in specific embodiments it can be 30%, 32%, 35%, 38% or 40%.

[0034] In the present invention, the rotation speed of the ball mill is preferably 140 to 180 r / min. -1 The time is preferably 5 to 7 hours; in a specific embodiment, the speed of the ball mill can be 140 r·min -1 、150r·min -1 、160r·min -1 、170r·min -1 or 180r·min -1 The ball milling time can be 5h, 6h or 7h. The present invention has no special requirements for the ball-to-material ratio of the ball milling, and the ball-to-material ratio known in the art can be used. In a specific embodiment, the ball-to-material ratio of the ball milling is 10:1. The present invention mixes the nano-alumina and the aluminum powder uniformly by ball milling.

[0035] After obtaining the mixed powder, the present invention melts the mixed powder at a temperature greater than the melting point of aluminum and lower than the melting point of alumina, so that the nano alumina particles are dispersed in the aluminum liquid to obtain a mixed liquid.

[0036] In the present invention, the smelting temperature only needs to be greater than the melting point of aluminum (660.4°C) and lower than the melting point of alumina (2054°C). In an embodiment of the present invention, the smelting temperature is specifically 700°C. The present invention has no special requirements for the smelting time, as long as the aluminum can be completely melted. In the present invention, the smelting is preferably carried out under vacuum conditions, and the vacuum degree is preferably below 10Pa. After the aluminum powder is completely melted, the present invention preferably stirs the resulting liquid so that the nano-alumina particles are evenly dispersed in the aluminum liquid.

[0037] After obtaining the mixed liquid, the present invention atomizes the mixed liquid to obtain the aluminum-nano alumina composite powder.

[0038] In the present invention, the atomization gas pressure is preferably 2.8 to 3.2 MPa, and in specific embodiments, it can be 2.8 MPa, 2.9 MPa, 3.0 MPa, 3.1 MPa or 3.2 MPa. The present invention has no special requirements for the specific implementation of the atomization, and an atomization method well known in the art can be used. Specifically, the mixed liquid is poured into a heat-insulating crucible, and when the mixed liquid flows to the atomization nozzle through a liquid guide tube, argon gas is used as an atomizing gas. Under the action of the atomizing gas pressure, the mixed liquid is broken into small droplets, and the nano-alumina particles are wrapped in the small droplets. After the small droplets solidify and cool, aluminum-nano-alumina composite powder is obtained.

[0039] After the atomization is completed, the present invention preferably further comprises screening the obtained atomized powder.

[0040] The invention provides a method for preparing an aluminum-nano alumina composite coating, comprising the following steps: spraying the aluminum-nano alumina composite powder onto a substrate surface by cold spraying to form an aluminum-nano alumina composite coating on the substrate surface.

[0041] In the present invention, the substrate preferably includes an aluminum substrate; in an embodiment, the substrate is specifically an aluminum sheet.

[0042] Before the spraying, the present invention preferably performs sandblasting on the substrate. The present invention has no special requirements for the sandblasting, as long as the surface roughness Ra of the substrate after the sandblasting is 4 to 6 μm.

[0043] In the present invention, the spraying air pressure is preferably 5.3-5.7 MPa, the spraying distance is preferably 28-32 mm, and the powder feeding rate is preferably 1-2 rpm; in a specific embodiment, the spraying air pressure may be 5.3 MPa, 5.4 MPa, 5.5 MPa, 5.6 MPa or 5.7 MPa, the spraying distance may be 28 mm, 29 mm, 30 mm, 31 mm or 32 mm, and the powder feeding rate may be 1 rpm, 1.5 rpm or 2 rpm.

[0044] In the present invention, the working gas used for spraying is preferably nitrogen, and the temperature of the working gas is preferably 570-590°C, and in a specific embodiment can be 570°C, 580°C or 590°C.

[0045] In the present invention, the thickness of the aluminum-nano-aluminum oxide composite coating is preferably 160-190 μm, and in a specific embodiment may be 160 μm, 170 μm, 180 μm or 190 μm.

[0046] The present invention first prepares aluminum powder and nano-alumina into aluminum-nano-alumina composite powder, distributes nano-alumina particles in aluminum particles, and in the process of preparing the composite coating by cold spraying, the aluminum-nano-alumina composite particles undergo plastic deformation to form a coating, and aluminum and nano-alumina are simultaneously deposited in the composite coating. The content of aluminum oxide in the composite coating is high (the mass fraction reaches 28-36%) and is evenly distributed. The microhardness of the composite coating is tested by a microhardness tester, and the wear resistance of the composite coating is tested by a friction and wear tester. The test results show that the aluminum-nano-alumina composite coating has high hardness and high wear resistance.

[0047] The aluminum-nano alumina composite powder and its preparation method, and the preparation method of the aluminum-nano alumina composite coating provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be understood as limiting the scope of protection of the present invention.

[0048] Example 1

[0049] Aluminum powder with a particle size of 0.5-1.5 μm is mixed with alumina powder with a particle size of 50-100 nm, and the mass fraction of nano-alumina is 35%. The mixture is mixed evenly by ball milling, with a ball-to-material ratio of 10:1 and a ball milling speed of 160 r·min -1 , the ball milling time is 6h. The obtained mixed powder is loaded into a melting crucible, and the pressure of the melting chamber is reduced to 10Pa by a mechanical vacuum pump. Then the mixed powder is heated to 700℃, the aluminum powder is melted into a liquid state, and the nano-alumina particles are dispersed in the aluminum liquid by stirring to obtain a mixed liquid, and then the mixed liquid is poured into a heat-insulating crucible. When the mixed liquid flows to the atomizing nozzle through the liquid guide tube, argon is used as the atomizing gas. Under the condition of an atomizing gas pressure of 3MPa, the mixed liquid is broken into small droplets. After the small droplets solidify and cool, aluminum-nano-alumina composite powder is obtained. After a screening process, aluminum-nano-alumina composite powder with a particle size range of 15 to 45μm is obtained.

[0050] The roughness Ra of the aluminum sheet surface is made to be 5 μm by sandblasting, and then the aluminum sheet is fixed in a spraying room. Aluminum-nano alumina composite powder is used as spraying powder. Under the conditions of spraying gas pressure of 5.5 MPa, nitrogen temperature of 580°C, spraying distance of 30 mm, and powder feeding rate of 1.5 rpm, a cold spraying method is used to prepare an aluminum-nano alumina composite coating with a thickness of 175 μm on the surface of the aluminum sheet. The mass fraction of nano alumina in the composite coating is 32%.

[0051] The microhardness tester was used to test the micro-Vickers hardness of the aluminum substrate and the aluminum-nano-aluminum oxide composite coating. The loading load was 25g, the test time was 15s, and the microhardness of 10 areas was tested. The test results showed that the average micro-Vickers hardness of the aluminum substrate was 106HV 0.025 The average micro-Vickers hardness of the aluminum-nano-aluminum oxide composite coating is 317HV 0.025 The wear resistance of the aluminum substrate and the composite coating was tested by a friction and wear tester with a load of 2N. After 15 minutes of wear, the wear volume of the aluminum substrate was 474.77mm 3 The wear volume of the composite coating is 113.04 mm 3 The lower the wear volume, the higher the wear resistance. The aluminum-nano-aluminum oxide composite coating has high wear resistance.

[0052] Figure 1This is a cross-sectional SEM image of the aluminum-nano-alumina composite coating prepared in Example 1. The particles in the image are nano-alumina and the matrix is ​​aluminum. Figure 1 It can be seen that the nano-alumina particles are evenly distributed in the aluminum matrix.

[0053] Example 2

[0054] Aluminum powder with a particle size of 0.5-1.5 μm is mixed with alumina powder with a particle size of 50-100 nm, and the mass fraction of nano-alumina is 40%. The mixture is mixed evenly by ball milling, with a ball-to-material ratio of 10:1 and a ball milling speed of 140 r·min -1 , the ball milling time is 7h. The obtained mixed powder is loaded into a melting crucible, and the pressure of the melting chamber is reduced to 10Pa by a mechanical vacuum pump. Then the mixed powder is heated to 700℃, the aluminum powder is melted into a liquid state, and the nano-alumina particles are dispersed in the aluminum liquid by stirring to obtain a mixed liquid, and then the mixed liquid is poured into a heat-insulating crucible. When the mixed liquid flows to the atomizing nozzle through the liquid guide tube, argon is used as the atomizing gas. Under the condition of an atomizing gas pressure of 3.2MPa, the mixed liquid is broken into small droplets. After the small droplets solidify and cool, aluminum-nano-alumina composite powder is obtained. After the screening process, aluminum-nano-alumina composite powder with a particle size range of 15 to 45μm is obtained.

[0055] The roughness Ra of the aluminum sheet surface is made to be 6 μm by sandblasting, and then the aluminum sheet is fixed in a spraying room, and an aluminum-nano alumina composite powder is used as the spraying powder. Under the conditions of spraying gas pressure of 5.7 MPa, nitrogen temperature of 590°C, spraying distance of 32 mm, and powder feeding rate of 2 rpm, a cold spraying method is used to prepare an aluminum-nano alumina composite coating with a thickness of 190 μm on the surface of the aluminum sheet. The mass fraction of nano alumina in the composite coating is 36%.

[0056] The microhardness of the aluminum substrate and the aluminum-nano-aluminum oxide composite coating was tested using a microhardness tester. The load was 25g, the test time was 15s, and the microhardness of 10 areas was tested. The test results showed that the average microhardness of the aluminum substrate was 106HV 0.025 The average micro-Vickers hardness of the aluminum-nano-aluminum oxide composite coating is 328HV 0.025 The wear resistance of the aluminum substrate and the composite coating was tested by a friction and wear tester with a load of 2N. After 15 minutes of wear, the wear volume of the aluminum substrate was 474.77mm 3 The wear volume of the composite coating is 96.08 mm 3 The lower the wear volume, the higher the wear resistance. The aluminum-nano-aluminum oxide composite coating has high wear resistance.

[0057] Example 3

[0058] Aluminum powder with a particle size of 0.5-1.5 μm is mixed with alumina powder with a particle size of 50-100 nm, and the mass fraction of nano-alumina is 30%. The mixture is mixed evenly by ball milling, with a ball-to-material ratio of 10:1 and a ball milling speed of 180 r·min -1 , the ball milling time is 5h. The obtained mixed powder is loaded into a melting crucible, and the pressure of the melting chamber is reduced to 10Pa by a mechanical vacuum pump. Then the mixed powder is heated to 700℃, the aluminum powder is melted into a liquid state, and the nano-alumina particles are dispersed in the aluminum liquid by stirring to obtain a mixed liquid, and then the mixed liquid is poured into a heat-insulating crucible. When the mixed liquid flows to the atomizing nozzle through the liquid guide tube, argon is used as the atomizing gas. Under the condition of an atomizing gas pressure of 2.8MPa, the mixed liquid is broken into small droplets. After the small droplets solidify and cool, aluminum-nano-alumina composite powder is obtained. After a screening process, aluminum-nano-alumina composite powder with a particle size range of 15 to 45μm is obtained.

[0059] The roughness Ra of the aluminum sheet surface is made to be 4μm by sandblasting, and then the aluminum sheet is fixed in a spraying room, and an aluminum-nano alumina composite powder is used as the spraying powder. Under the conditions of spraying gas pressure of 5.3MPa, nitrogen temperature of 570℃, spraying distance of 28mm, and powder feeding rate of 1rpm, a cold spraying method is used to prepare an aluminum-nano alumina composite coating with a thickness of 160μm on the surface of the aluminum sheet. The mass fraction of nano alumina in the composite coating is 28%.

[0060] The microhardness tester was used to test the micro-Vickers hardness of the aluminum substrate and the aluminum-nano-aluminum oxide composite coating. The loading load was 25g, the test time was 15s, and the microhardness of 10 areas was tested. The test results showed that the average micro-Vickers hardness of the aluminum substrate was 106HV 0.025 The average micro-Vickers hardness of the aluminum-nano-aluminum oxide composite coating is 303HV 0.025 The wear resistance of the aluminum substrate and the composite coating was tested by a friction and wear tester with a load of 2N. After 15 minutes of wear, the wear volume of the aluminum substrate was 474.77mm 3 The wear volume of the composite coating is 124.34 mm 3 The lower the wear volume, the higher the wear resistance. The aluminum-nano-aluminum oxide composite coating has high wear resistance.

[0061] Comparative Example 1

[0062] Aluminum powder with a particle size of 15-45 μm is mixed with alumina powder with a particle size of 50-100 nm. The mass fraction of nano-alumina is 35%, the ball-to-material ratio is 10:1, and the ball milling speed is 150 r·min -1, the ball milling time is 5h, and aluminum-nano alumina mixed powder is obtained. The roughness of the aluminum sheet surface is Ra 5μm by sandblasting, and then the aluminum sheet is fixed in the spraying room, and the aluminum-nano alumina mixed powder is used as the spraying powder. Under the conditions of spraying pressure of 5.5MPa, nitrogen temperature of 580℃, spraying distance of 30mm, and powder feeding rate of 1.5rpm, a cold spraying method is used to prepare an aluminum-nano alumina composite coating with a thickness of 175μm on the surface of the aluminum sheet, and the mass fraction of nano alumina in the composite coating is 3%.

[0063] The microhardness tester was used to test the micro-Vickers hardness of the aluminum substrate and the aluminum-aluminum oxide coating. The loading load was 25g, the test time was 15s, and the microhardness of 10 areas was tested. The test results showed that the average micro-Vickers hardness of the aluminum substrate was 106HV 0.025 The average micro-Vickers hardness of the aluminum-nano-aluminum oxide composite coating is 121HV 0.025 The wear resistance of the aluminum substrate and the composite coating was tested by a friction and wear tester with a load of 2N. After 15 minutes of wear, the wear volume of the aluminum substrate was 474.77mm 3 The wear volume of the composite coating is 463.46 mm 3 . Figure 2 This is a cross-sectional SEM image of the aluminum-nano-aluminum oxide composite coating prepared in Comparative Example 1. Figure 2 It can be seen that only a small amount of nano-aluminum oxide particles are distributed in the aluminum matrix, the content of nano-aluminum oxide in the coating is low, and the distribution uniformity is not as good as that in Example 1.

[0064] It can be seen from the results of the above embodiments and comparative examples that the present invention prepares an aluminum-nano alumina composite powder first, and uses the aluminum-nano alumina composite powder as a spraying powder to prepare an aluminum-nano alumina composite coating. The content of nano alumina in the composite coating is high and evenly distributed, and the composite coating has high hardness and wear resistance.

[0065] 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 principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An aluminum-nano alumina composite powder, characterized in that: The invention comprises nano-alumina and aluminum wrapped on the surface of the nano-alumina.

2. The aluminum-nano alumina composite powder according to claim 1, characterized in that: The mass fraction of nano-alumina in the aluminum-nano-alumina composite powder is 30-40%.

3. The aluminum-nano alumina composite powder according to claim 1, characterized in that: The particle size of the aluminum-nano-alumina composite powder is 15-45 μm, and the particle size of the nano-alumina is 50-100 nm.

4. The method for preparing the aluminum-nano-alumina composite powder according to any one of claims 1 to 3, characterized in that: The following steps are involved: Ball milling aluminum powder and nano-alumina to obtain mixed powder; The mixed powder is smelted at a temperature greater than the melting point of aluminum and lower than the melting point of aluminum oxide, so that the nano-alumina particles are dispersed in the aluminum liquid to obtain a mixed liquid; The mixed liquid is atomized to obtain the aluminum-nano alumina composite powder.

5. The preparation method according to claim 4, characterized in that: The particle size of the aluminum powder is 0.5-1.5 μm; the particle size of the nano-aluminum oxide is 50-100 nm.

6. The preparation method according to claim 4 or 5, characterized in that: The mass fraction of nano-alumina in the mixed powder is 30-40%.

7. The preparation method according to claim 4, characterized in that: The rotation speed of the ball mill is 140-180 r / min -1 , time is 5 to 7 hours.

8. The preparation method according to claim 4, characterized in that: The atomization air pressure is 2.8-3.2 MPa.

9. A method for preparing an aluminum-nano-aluminum oxide composite coating, characterized in that: The method comprises the following steps: spraying aluminum-nano alumina composite powder onto the surface of a substrate by a cold spraying method to form an aluminum-nano alumina composite coating on the surface of the substrate; The aluminum-nano alumina composite powder is the aluminum-nano alumina composite powder according to any one of claims 1 to 3 or the aluminum-nano alumina composite powder prepared by the preparation method according to any one of claims 4 to 8.

10. The preparation method according to claim 9, characterized in that: The spraying air pressure is 5.3-5.7 MPa, the spraying distance is 28-32 mm, and the powder feeding rate is 1-2 rpm.

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