A carbon nanotube reinforced aluminum-based composite material part and additive manufacturing method thereof

Abstract

The present invention relates to a carbon nanotube reinforced aluminum matrix composite part and an additive manufacturing method thereof, belonging to the technical field of additive manufacturing. Among them, the additive manufacturing method includes the following steps: ball milling an Al-Cu-Mg series aluminum alloy powder and a carbon nanotube powder to obtain a composite powder; performing a forming process and a machining process on the composite powder to obtain a raw part; performing a friction extrusion deposition process on the raw part to obtain an additive part; wherein, the parameters of the friction extrusion deposition process are controlled as follows: r<supgt;2< / supgt>·c = (8-12)·v·t; wherein, t is the single-layer thickness in the additive layer, c is the feed rate of the raw part, v is the additive travel rate, and r is the radius of the raw part; performing a heat treatment on the additive part to obtain a carbon nanotube reinforced aluminum matrix composite part. The present invention is mainly used to solve the problem that high-strength carbon nanotube reinforced aluminum matrix composites are difficult to form during the additive manufacturing of carbon nanotube reinforced aluminum matrix composite parts by friction extrusion deposition.

Description

Technical Field

[0001] The present invention relates to the technical field of additive manufacturing, and in particular to a carbon nanotube reinforced aluminum-based composite material part and an additive manufacturing method thereof. Background Art

[0002] High-strength carbon nanotube reinforced aluminum-based composite material is a composite material with Al-Cu-Mg-based high-strength aluminum alloy as the matrix and carbon nanotubes as the reinforcement. It has excellent specific stiffness, specific strength, wear resistance and other advantages, which makes the composite material have broad application prospects. However, due to the difficulty of plastic processing of the composite material, its molding relies on a lot of machining, resulting in low material utilization.

[0003] Additive manufacturing technology can directly form components by stacking them layer by layer. Therefore, using additive manufacturing to achieve near-net-shape forming of high-strength carbon nanotube-reinforced aluminum-based composite components can improve material utilization and reduce manufacturing costs. However, since carbon nanotubes and aluminum are prone to react at high temperatures, harmful Al 4 C 3 Therefore, the corrosion resistance of carbon nanotube-reinforced aluminum-based composite components obtained by melt additive manufacturing technology using energy beam as heat source is often poor.

[0004] Friction extrusion deposition is an additive manufacturing technology that uses rods as raw materials and forms additive layers through plastic deformation of materials. During the friction extrusion deposition process, the temperature is low, and no melting or solidification occurs, which can effectively avoid the reaction between aluminum and carbon nanotubes.

[0005] However, the inventors of the present invention have found that there are at least the following problems in manufacturing carbon nanotube reinforced aluminum-based composite parts using friction extrusion deposition technology:

[0006] (1) High-strength carbon nanotube-reinforced aluminum-based composites have poor plasticity, making them difficult to form during friction extrusion deposition additive manufacturing and prone to defects such as holes and cracks.

[0007] (2) The uniformity of carbon nanotube distribution in carbon nanotube-reinforced aluminum-based composites strongly depends on the uniformity of carbon nanotube distribution in the rods; and the formability of Al-Cu-Mg-based high-strength aluminum alloy powders is poor. Therefore, how to prepare rods with excellent density and uniform carbon nanotube distribution is of great significance to improving the uniformity of carbon nanotube distribution in carbon nanotube-reinforced aluminum-based composites. Summary of the invention

[0008] In view of this, the present invention provides a carbon nanotube reinforced aluminum-based composite material part and an additive preparation method thereof, the main purpose of which is to solve the problem of difficulty in forming high-strength carbon nanotube reinforced aluminum-based composite materials when carbon nanotube reinforced aluminum-based composite materials are prepared by friction extrusion deposition additive manufacturing.

[0009] In order to achieve the above object, the present invention mainly provides the following technical solutions:

[0010] In one aspect, an embodiment of the present invention provides an additive manufacturing method for a carbon nanotube-reinforced aluminum-based composite material part, wherein the additive manufacturing method comprises the following steps:

[0011] Ball milling: ball milling Al-Cu-Mg aluminum alloy powder and carbon nanotube powder to obtain composite powder;

[0012] Molding and processing: molding and processing the composite powder to obtain a raw material part;

[0013] Friction extrusion deposition process: the raw material is subjected to friction extrusion deposition process to obtain an additive part; wherein the parameters of the friction extrusion deposition process are controlled as follows: 2 c = (8-12) v t; t is the thickness of a single layer in the additive layer, in mm; c is the feed rate of the raw material, in mm / min; v is the additive advance rate, in mm / min; r is the radius of the raw material, in mm;

[0014] Heat treatment: heat treatment is performed on the additive component to obtain a carbon nanotube reinforced aluminum-based composite component.

[0015] Preferably, the particle size of the Al-Cu-Mg aluminum alloy powder is 5-40 microns.

[0016] Preferably, the chemical composition of the Al-Cu-Mg aluminum alloy powder includes, by mass percentage, 3.8-4.9% Cu, 1.2-1.8% Mg, and the balance Al.

[0017] Preferably, in the carbon nanotube powder, the carbon nanotubes have a length of 1-20 micrometers and a diameter of 10-30 nanometers.

[0018] Preferably, in the composite powder, the volume fraction of the carbon nanotube powder is 0.5-3%.

[0019] Preferably, in the ball milling step: the rotation speed of the ball milling is 350-420 rpm; the time of the ball milling is 8-12 hours; iron balls or zirconia balls are used as grinding balls during the ball milling; during the ball milling, the ball-to-powder ratio is 8:1-12:1.

[0020] Preferably, the steps of forming and processing include:

[0021] Step 1), hot pressing the composite powder to obtain a prefabricated blank; wherein the temperature of the hot pressing treatment is 400-500°C; preferably, the time of the hot pressing treatment is 0.5-3 hours, and the pressure of the hot pressing treatment is above 40MPa;

[0022] Step 2) mechanically processing the prefabricated blank to obtain the raw material part.

[0023] Preferably, the radius of the raw material piece is 5-15 mm.

[0024] Preferably, the raw material is a rod.

[0025] Preferably, in the step of friction extrusion deposition treatment:

[0026] Feeding a raw material into a friction extrusion deposition mold, the raw material rubs against the rotating friction extrusion deposition mold to partially soften the raw material; wherein the softened raw material is extruded through an extrusion hole of the friction extrusion deposition mold, and forms an additive layer on a substrate as the friction extrusion deposition mold moves; after the friction extrusion deposition process is completed, an additive part is obtained;

[0027] The rotation speed of the friction extrusion deposition mold is 300-350 rpm, the feed rate of the raw material is 10-500 mm / min, the additive advance rate is 50-3000 mm / min, and the thickness of a single layer in the additive layer is 0.5-4 mm.

[0028] Preferably, in the step of friction extrusion deposition treatment:

[0029] The substrate is made of Al-Cu-Mg aluminum alloy.

[0030] Preferably, in the step of friction extrusion deposition treatment:

[0031] The thickness of the substrate is at least 5 mm.

[0032] Preferably, in the step of heat treatment:

[0033] Solution treatment, performing solution treatment on the additive component to obtain the additive component after solution treatment;

[0034] The natural aging treatment is performed on the additive component after the solid solution treatment to obtain a carbon nanotube reinforced aluminum-based composite material component.

[0035] Preferably, in the step of solution treatment, the additive part is subjected to a heat preservation treatment at a temperature of 490-500° C. and then quenched to obtain the additive part after the solution treatment; wherein the heat preservation treatment time is 1-2 hours.

[0036] Preferably, in the step of natural aging treatment, the time of the natural aging treatment is at least 96 hours.

[0037] Preferably, after the natural aging treatment, the substrate and / or excess material on the additive component needs to be removed to obtain a carbon nanotube reinforced aluminum-based composite component.

[0038] On the other hand, an embodiment of the present invention provides a carbon nanotube-reinforced aluminum-based composite material component, wherein the carbon nanotube-reinforced aluminum-based composite material component is prepared by the additive preparation method of the carbon nanotube-reinforced aluminum-based composite material component described in any one of the above.

[0039] Preferably, in the microstructure of the carbon nanotube reinforced aluminum-based composite material, the grain size is 0.3-2 microns; copper-magnesium atomic clusters are dispersed in the grains, wherein the size of the copper-magnesium atomic clusters is ≤20nm; the carbon nanotubes are distributed inside the grains and at the grain boundaries; and there is no harmful phase Al in the microstructure. 4 C 3 .

[0040] Preferably, the average tensile strength of the carbon nanotube-reinforced aluminum-based composite material component is ≥500 MPa.

[0041] Compared with the prior art, the carbon nanotube reinforced aluminum-based composite material part and the additive preparation method thereof of the present invention have at least the following beneficial effects:

[0042] The embodiment of the present invention provides an additive preparation method for a carbon nanotube-reinforced aluminum-based composite material part, which mainly includes the following steps: ball milling Al-Cu-Mg aluminum alloy powder and carbon nanotube powder to obtain composite powder; molding and processing the composite powder to obtain a raw material part; friction extrusion deposition treatment of the raw material part to obtain an additive part; wherein the parameters of the friction extrusion deposition treatment are controlled as follows: 2·c=(8~12)·v·t; where t is the thickness of a single layer in the additive layer, in mm; c is the feed rate of the raw material, in mm / min; v is the additive travel rate, in mm / min; r is the radius of the raw material, in mm; the additive part is heat treated to obtain a carbon nanotube reinforced aluminum-based composite material. It should be noted here about the above steps that: based on the high-strength carbon nanotube reinforced aluminum-based composite material (a composite material with Al-Cu-Mg-based high-strength aluminum alloy as the matrix and carbon nanotubes as the reinforcement), there is a problem of great difficulty in forming during friction extrusion deposition processing. Through a lot of research, the present invention has found that this technical problem can be solved by controlling the parameters of the friction extrusion deposition processing. Specifically, by controlling r 2 ·c=(8~12)·v·t, can control the fluidity of the extruded material during the additive process, thereby ensuring its formability, and at the same time ensuring the appropriate amount of material extrusion (if the extrusion amount is too much, it will lead to excessive friction heat generation and plastic deformation heat generation, resulting in holes, tunnels and other defects on the surface of the additive layer; if the extrusion amount is too little, it will lead to material shortage and form an incomplete additive layer), thereby avoiding the generation of macroscopic defects. Therefore, the above scheme of the present invention can solve the problem of difficulty in forming high-strength carbon nanotube-reinforced aluminum-based composite materials when preparing carbon nanotube-reinforced aluminum-based composite materials by friction extrusion deposition additive.

[0043] Furthermore, in an additive preparation method for a carbon nanotube-reinforced aluminum-based composite material part provided in an embodiment of the present invention, the carbon nanotubes in the raw material part prepared by ball milling and hot pressing are evenly distributed and have excellent compactness, thereby ensuring that the carbon nanotubes in the final additive component are evenly distributed. It should also be noted that when hot pressing is used to prepare the prefabricated blank, on the one hand, in order to ensure compactness, and on the other hand, in order to avoid aluminum and carbon nanotubes reacting at a high temperature to generate harmful phases, it is necessary to study and control the temperature of the hot pressing treatment.

[0044] In summary, the embodiment of the present invention provides an additive preparation method for a carbon nanotube-reinforced aluminum-based composite material part, which proposes to use friction extrusion deposition technology, adopt ball milling and hot pressing to prepare carbon nanotube-reinforced aluminum-based composite rods as raw materials, and control the parameters of the friction extrusion deposition process to obtain high-strength carbon nanotube-reinforced aluminum-based composite parts. The carbon nanotube-reinforced aluminum-based composite rods prepared by ball milling and hot pressing are used as raw materials. The carbon nanotubes in the raw materials are evenly distributed, and the carbon nanotubes in the additive components thus prepared are evenly distributed. The friction extrusion deposition process belongs to the solid-state additive manufacturing technology. During the additive process, there is no melting and solidification process of the raw materials, and the temperature is relatively low, which avoids local defects such as harmful reactions that may occur in melt additive manufacturing. In the friction extrusion deposition process, the process parameters are regulated to overcome the problems of poor plasticity and difficulty in forming of high-strength carbon nanotube-reinforced aluminum-based composite materials, avoid the formation of defects such as holes and cracks, and obtain well-formed additive parts.

[0045] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is a physical picture of the carbon nanotube reinforced aluminum-based composite material prepared in Example 1;

[0047] Figure 2 This is an interface diagram of the carbon nanotubes and the aluminum alloy matrix in the carbon nanotube-reinforced aluminum-based composite material prepared in Example 1;

[0048] Figure 3 This is an interface diagram of the carbon nanotubes and the aluminum alloy matrix in the carbon nanotube-reinforced aluminum-based composite material prepared in Comparative Example 4;

[0049] Figure 4 is an interface diagram of the carbon nanotubes and the aluminum alloy matrix in the carbon nanotube-reinforced aluminum-based composite material member prepared in Example 2;

[0050] Figure 5 is an interface diagram of the carbon nanotubes and the aluminum alloy matrix in the carbon nanotube-reinforced aluminum-based composite material member prepared in Example 3;

[0051] Figure 6 This is a physical picture of the carbon nanotube reinforced aluminum-based composite material prepared in Comparative Example 1;

[0052] Figure 7 This is a physical picture of the carbon nanotube reinforced aluminum-based composite material prepared in Comparative Example 2;

[0053] Figure 8This is a microstructure diagram of a carbon nanotube-reinforced aluminum-based composite material prepared in Comparative Example 3;

[0054] Fig. 9 This is a physical picture of the carbon nanotube reinforced aluminum-based composite material component prepared in Comparative Example 5. DETAILED DESCRIPTION

[0055] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention application are described in detail below in conjunction with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures, or characteristics in one or more embodiments may be combined in any suitable form.

[0056] The embodiment of the present invention provides a method for additively preparing a carbon nanotube-reinforced aluminum-based composite material part, which mainly includes the following steps:

[0057] Ball milling: The Al-Cu-Mg aluminum alloy powder and the carbon nanotube powder are subjected to ball milling to obtain a composite powder.

[0058] In this step, the particle size of the Al-Cu-Mg aluminum alloy powder is 5-40 microns.

[0059] In the Al-Cu-Mg aluminum alloy powder, the mass fraction of Cu is 3.8-4.9%, the mass fraction of Mg is 1.2-1.8%, and the balance is Al.

[0060] In the carbon nanotube powder, the carbon nanotube has a length of 1-20 micrometers and a diameter of 10-30 nanometers.

[0061] In the composite powder, the volume fraction of carbon nanotube powder is 0.5-3% (here, if the volume fraction of carbon nanotube powder is higher than 3%, the plasticity of the material will be drastically reduced, the formability will be seriously reduced, the forming will be difficult during additive manufacturing, and there will be defects such as holes and cracks; if the volume fraction of carbon nanotube powder is lower than 0.5%, the reinforcement effect will be insufficient).

[0062] The ball milling speed is 350-420 rpm (if the ball milling speed is low, the ball milling effect is poor, the carbon nanotubes are difficult to disperse effectively, and the carbon nanotubes in the obtained additive parts are seriously agglomerated, resulting in decreased mechanical properties; if the speed is too high, rapid cold welding will occur between the metal powders, and the carbon nanotube powders will be fixed between the metal powders before they are dispersed in time, which also leads to agglomeration). The ball milling time is 8-12 hours; iron balls or zirconium oxide balls are used as grinding balls during ball milling; during ball milling, the ball-to-powder ratio is 8:1-12:1.

[0063] It should be noted here that: in this step, the Al-Cu-Mg aluminum alloy powder and the carbon nanotube powder are ball-milled, and the parameters of the ball-milling process (such as the ball-milling speed) are controlled at the same time, so that the ball-milling process has a good effect, the carbon nanotubes are effectively dispersed, and the carbon nanotubes are prevented from agglomerating, thereby ensuring the uniformity of the carbon nanotube dispersion and improving the mechanical properties of the final material.

[0064] Molding and processing: the composite powder is subjected to molding and processing to obtain a raw material part.

[0065] In this step, the composite material is subjected to hot pressing to obtain a prefabricated blank; the prefabricated blank is subjected to mechanical processing to obtain the raw material piece (i.e., raw material bar);

[0066] The temperature of the hot pressing treatment is 400-500° C. Preferably, the time of the hot pressing treatment is 0.5-3 hours, and the pressure of the hot pressing treatment is above 40 MPa.

[0067] The radius of the raw material piece is 5-15 mm.

[0068] Among them, the processing is machining.

[0069] It should be noted that: since Al-Cu-Mg aluminum alloys and composite materials have poor formability, a "hot pressing" method is required to improve the density of the raw materials when preparing the prefabricated blank. However, the present invention uses hot pressing to prepare the prefabricated blank. In order to avoid the aluminum and carbon nanotubes reacting at a high temperature to generate harmful phases, the hot pressing temperature needs to be controlled.

[0070] Friction extrusion deposition process: The raw material is subjected to friction extrusion deposition process to obtain an additive part; wherein the parameters of the friction extrusion deposition process are controlled as follows: 2 ·c=(8~12)·v·t; where t is the thickness of a single layer in the additive layer, in mm; c is the feed rate of the raw material, in mm / min; v is the additive advance rate, in mm / min; r is the radius of the raw material, in mm. Preferably, r 2 ·c=10·v·t.

[0071] In this step, a raw material piece is fed into the friction extrusion deposition mold, and the raw material piece rubs against the rotating friction extrusion deposition mold to soften the raw material piece locally; wherein the softened raw material is extruded through the extrusion hole of the friction extrusion deposition mold, and an additive layer is formed on the substrate as the friction extrusion deposition mold moves; after the friction extrusion deposition process is completed, an additive piece is obtained.

[0072] Specifically, the friction extrusion deposition mold has an inner cavity with an opening at the upper end and an extrusion hole at the lower end; here, the raw material is fed into the inner cavity by a feeding mechanism; during the feeding process, the raw material will rub against the inner wall of the rotating friction extrusion deposition mold (especially the bottom of the inner cavity), so that the friction part of the raw material is softened and extruded from the extrusion hole.

[0073] It should be noted that: due to the poor plasticity of carbon nanotube reinforced aluminum matrix composite materials, it is difficult to form during material addition, and it is easy to produce defects such as holes and cracks. In view of this problem, in this step, the present invention proposes for the first time 2 ·c=(8~12)·v·t, can control the fluidity of the extruded material during additive manufacturing, thereby ensuring its formability, while ensuring an appropriate amount of material extrusion (if the extrusion amount is too much, it will lead to excessive heat generation due to friction and plastic deformation, resulting in defects such as holes and tunnels on the surface of the additive layer; if the extrusion amount is too little, it will lead to material shortage and form an incomplete additive layer), thereby avoiding the generation of macro defects.

[0074] Preferably, the rotation speed of the friction extrusion deposition mold is 300-350 rpm, the feed rate of the raw material is 10-500 mm / min, the additive advance rate is 50-3000 mm / min, and the thickness of the single layer in the additive layer is 0.5-4 mm, preferably 1 mm. It should be noted that if the rotation speed of the friction extrusion deposition mold is too high, it will cause excessive heat generation, resulting in defects such as holes and tunnels on the surface of the additive layer. If the rotation speed of the friction extrusion deposition mold is too low, the temperature will be too low, the material fluidity will be insufficient, and defects such as cavities will appear inside.

[0075] Preferably, Al-Cu-Mg aluminum alloy is used as the substrate. The thickness of the substrate is at least 5 mm (since Al-Cu-Mg aluminum alloy and composite materials have large residual stress during material addition, the thickness of the substrate must be at least 5 mm to avoid warping deformation). Before the friction extrusion deposition process, the surface of the substrate needs to be treated; preferably, the surface treatment includes mechanical grinding, cleaning and drying.

[0076] Heat treatment: heat treatment is performed on the additive component to obtain a carbon nanotube reinforced aluminum-based composite material.

[0077] In this step, the additive part is heat-treated at a temperature of 490-500°C and then quenched; then, the quenched additive part is subjected to natural aging treatment to obtain a carbon nanotube reinforced aluminum-based composite material; preferably, the heat-treatment time is 1-2h; preferably, the natural aging treatment time is at least 96h; preferably, after the natural aging treatment, the substrate and excess material on the additive part need to be removed to obtain a carbon nanotube reinforced aluminum-based composite material.

[0078] Regarding heat treatment, it should be noted that: since Al-Cu-Mg alloy softens after being heated, the previous additive layer will be heated and softened by the subsequent additive layer, resulting in reduced strength. Therefore, the purpose of heat treatment is to eliminate this adverse effect and restore its strength. The reason for softening due to heat is that the original fine dispersed strengthening phase in the aluminum alloy is drastically coarsened by heat, resulting in a decrease in the strengthening effect. Heat treatment can dissolve these coarsened strengthening phases (solution treatment) and re-precipitate in the form of fine dispersion (aging treatment). The selection of the temperature and time of the above-mentioned solution treatment can enable the precipitation phase in the Al-Cu-Mg alloy to be fully dissolved without local liquefaction (overburning). The time of natural aging treatment is to ensure that the copper and magnesium atomic clusters are fully formed.

[0079] Here, the above scheme is explained as follows:

[0080] 1) In the above steps of the present invention, a raw material piece (carbon nanotube reinforced aluminum-based composite rod) prepared by ball milling and hot pressing is used as the raw material, and the carbon nanotubes in the raw material are evenly distributed, so that the carbon nanotubes in the additive part prepared thereby are evenly distributed.

[0081] 2) In the above steps of the present invention, the friction extrusion deposition process involved belongs to the solid-state additive manufacturing technology. There is no melting and solidification process of the raw materials during the additive process, and the temperature is relatively low, which avoids local defects such as harmful reactions that may occur in melt additive manufacturing. It is suitable for additive manufacturing of carbon nanotube reinforced aluminum-based composite materials.

[0082] 3) In the above steps, the present invention overcomes the problems of poor plasticity and difficulty in forming of high-strength carbon nanotube-reinforced aluminum-based composite materials by controlling the process parameters in the friction extrusion deposition process, thereby avoiding the formation of defects such as holes and cracks, and finally obtaining a well-formed additive part.

[0083] The present invention is further described below by specific experimental examples:

[0084] Example 1

[0085] This embodiment prepares a carbon nanotube reinforced aluminum-based composite material, which mainly includes the following steps:

[0086] 1) Al-Cu-Mg aluminum alloy powder with a particle size of 40 microns (in the Al-Cu-Mg aluminum alloy powder, the mass fraction of Cu is 4.0%, the mass fraction of Mg is 1.5%, and the balance is Al) and carbon nanotube powder (in the carbon nanotube powder, the length of the carbon nanotube is 1-20 microns and the diameter is 10-30 nanometers) are mixed and ball-milled with iron balls to obtain a composite powder; wherein the ball milling speed is 400 rpm, the ball milling time is 10 hours, and the ball-to-powder ratio is 10:1. In the composite powder, the volume fraction of the carbon nanotube powder is 1.5%.

[0087] 2) The composite powder is subjected to hot pressing to obtain a prefabricated blank. The hot pressing temperature is 450° C. The prefabricated blank is machined into a rod with a radius of 10 mm to obtain a raw material rod.

[0088] 3) The surface of the Al-Cu-Mg alloy substrate is mechanically polished, cleaned, and dried. The raw material rod is fed downward (the raw material rod is fed into the friction extrusion deposition mold). During the downward feeding process, the raw material rod rubs against the friction extrusion deposition mold, causing the raw material to be partially softened. The softened raw material is extruded through the extrusion hole of the friction extrusion deposition mold, and an additive layer is formed on the substrate as the friction extrusion deposition mold moves. After the friction extrusion deposition process is completed, an additive part is formed on the substrate.

[0089] In the process of friction extrusion deposition, the rotation speed of the friction extrusion deposition mold is 300 rpm, the feed rate c of the raw material rod is 20 mm / min, the thickness of a single layer in the additive layer is 1 mm, and the travel speed of the friction extrusion deposition mold (i.e., the additive travel rate v) is 200 mm / min. The above parameters satisfy: 2 ·c=(8~12)·v·t; where t is the thickness of the additive layer, c is the feed rate of the raw material, v is the additive advance rate, and r is the radius of the raw material.

[0090] 4) The additive part is kept at 495°C for 1 hour and quenched to obtain a solution-treated additive part; the solution-treated additive part is then naturally aged for 96 hours; finally, the excess material is removed to obtain the target high-strength carbon nanotube-reinforced aluminum-based composite material product.

[0091] The average tensile strength of the carbon nanotube reinforced aluminum-based composite material prepared in this embodiment reaches 563 MPa.

[0092] Figure 1 This is a physical picture of the carbon nanotube reinforced aluminum-based composite material prepared in this embodiment, which includes a substrate 2 and an additive component 1 located on the substrate 2. Figure 1 It can be seen that the additive process has good forming without defects such as holes and cracks.

[0093] Figure 2 This is an interface diagram of the carbon nanotubes and the aluminum alloy matrix in the carbon nanotube-reinforced aluminum-based composite material prepared in this embodiment. It can be seen that the interface is well bonded and no harmful reaction occurs.

[0094] In addition, in the microstructure of the carbon nanotube reinforced aluminum-based composite material prepared in this embodiment: the grain size is 0.3-2 microns; copper-magnesium atomic clusters are dispersed in the grains, wherein the size of the copper-magnesium atomic clusters is ≤20nm; carbon nanotubes are distributed inside the grains and at the grain boundaries; and there is no harmful phase Al in the microstructure. 4 C 3 .

[0095] Example 2

[0096] This embodiment prepares a carbon nanotube reinforced aluminum-based composite material, which mainly includes the following steps:

[0097] 1) Al-Cu-Mg aluminum alloy powder with a particle size of 40 microns (in the Al-Cu-Mg aluminum alloy powder, the mass fraction of Cu is 4.9%, the mass fraction of Mg is 1.8%, and the balance is Al) and carbon nanotube powder (in the carbon nanotube powder, the length of the carbon nanotube is 1-20 microns and the diameter is 10-30 nanometers) are mixed and ball-milled with iron balls to obtain a composite powder; wherein the ball milling speed is 350 rpm, the ball milling time is 8 hours, and the ball-to-powder ratio is 8:1. In the composite powder, the volume fraction of the carbon nanotube powder is 0.5%.

[0098] 2) The composite powder is subjected to hot pressing to obtain a prefabricated blank. The hot pressing temperature is 400° C. The prefabricated blank is machined into a rod with a radius of 5 mm to obtain a raw material rod.

[0099] 3) The surface of the Al-Cu-Mg alloy substrate is mechanically polished, cleaned, and dried. The raw material rod is fed downward (the raw material rod is fed into the friction extrusion deposition mold). During the downward feeding process, the raw material rod rubs against the friction extrusion deposition mold, causing the raw material to be partially softened. The softened raw material is extruded through the extrusion hole of the friction extrusion deposition mold, and an additive layer is formed on the substrate as the friction extrusion deposition mold moves. After the friction extrusion deposition process is completed, an additive part is formed on the substrate.

[0100] In the process of friction extrusion deposition, the rotation speed of the friction extrusion deposition mold is 300 rpm, the feed rate c of the raw material rod is 20 mm / min, the thickness of the additive layer is 1 mm, and the travel speed of the friction extrusion deposition mold (ie, the additive travel rate v) is 50 mm / min. The above parameters satisfy: 2·c=(8~12)·v·t; where t is the thickness of a single layer in the additive layer, c is the feed rate of the raw material, v is the additive travel rate, and r is the radius of the raw material.

[0101] 4) The additive part is kept at 490°C for 1 hour and quenched to obtain a solution-treated additive part; the solution-treated additive part is then naturally aged for 96 hours; finally, the substrate and excess material are removed to obtain the target high-strength carbon nanotube-reinforced aluminum-based composite material product.

[0102] The average tensile strength of the carbon nanotube reinforced aluminum-based composite material prepared in this embodiment reaches 557 MPa.

[0103] Figure 4 This is an interface diagram of the carbon nanotubes and the aluminum alloy matrix in the carbon nanotube-reinforced aluminum-based composite material prepared in this embodiment. It can be seen that the interface is well bonded and no harmful reaction occurs.

[0104] In addition, in the microstructure of the carbon nanotube-reinforced aluminum-based composite material prepared in this embodiment: the grain size is 0.3-2 microns; copper-magnesium atomic clusters are dispersed in the grains, wherein the size of the copper-magnesium atomic clusters is ≤20nm; carbon nanotubes are distributed inside the grains and at the grain boundaries; in the microstructure.

[0105] Example 3

[0106] This embodiment prepares a carbon nanotube reinforced aluminum-based composite material, which mainly includes the following steps:

[0107] 1) Al-Cu-Mg aluminum alloy powder with a particle size of 40 microns (in the Al-Cu-Mg aluminum alloy powder, the mass fraction of Cu is 3.8%, the mass fraction of Mg is 1.2%, and the balance is Al.) and carbon nanotube powder (in the carbon nanotube powder, the length of the carbon nanotube is 1-20 microns and the diameter is 10-30 nanometers) are mixed and ball-milled with iron balls to obtain a composite powder; wherein the ball milling speed is 420 rpm, the ball milling time is 12 hours, and the ball-to-powder ratio is 12:1. In the composite powder, the volume fraction of the carbon nanotube powder is 3%.

[0108] 2) The composite powder is subjected to hot pressing to obtain a prefabricated blank. The hot pressing temperature is 500° C. The prefabricated blank is machined into a rod with a radius of 15 mm to obtain a raw material rod.

[0109] 3) The surface of the Al-Cu-Mg alloy substrate is mechanically polished, cleaned, and dried. The raw material rod is fed downward (the raw material rod is fed into the friction extrusion deposition mold). During the downward feeding process, the raw material rod rubs against the friction extrusion deposition mold, causing the raw material to be partially softened. The softened raw material is extruded through the extrusion hole of the friction extrusion deposition mold, and an additive layer is formed on the substrate as the friction extrusion deposition mold moves. After the friction extrusion deposition process is completed, an additive part is formed on the substrate.

[0110] In the process of friction extrusion deposition, the rotation speed of the friction extrusion deposition mold is 350 rpm, the feed rate c of the raw material rod is 10 mm / min, the thickness of a single layer in the additive layer is 1 mm, and the travel speed of the friction extrusion deposition mold (i.e., the additive travel rate v) is 225 mm / min. The above parameters satisfy: 2 ·c=(8~12)·v·t; where t is the thickness of the additive layer, c is the feed rate of the raw material, v is the additive advance rate, and r is the radius of the raw material.

[0111] 4) The additive part is kept at a temperature of 500°C for 2 hours and quenched to obtain a solution-treated additive part; the solution-treated additive part is then naturally aged for 100 hours; finally, the substrate and excess material are removed to obtain the target high-strength carbon nanotube-reinforced aluminum-based composite material product.

[0112] The average tensile strength of the carbon nanotube-reinforced aluminum-based composite material prepared in this embodiment reaches 578 MPa.

[0113] Figure 5 This is an interface diagram of the carbon nanotubes and the aluminum alloy matrix in the carbon nanotube-reinforced aluminum-based composite material prepared in Example 3; it can be seen that: the interface is well bonded and no harmful reaction occurs.

[0114] In addition, in the microstructure of the carbon nanotube-reinforced aluminum-based composite material prepared in this embodiment: the grain size is 0.3-2 microns; copper-magnesium atomic clusters are dispersed in the grains, wherein the size of the copper-magnesium atomic clusters is ≤20nm; carbon nanotubes are distributed inside the grains and at the grain boundaries; in the microstructure.

[0115] Comparative Example 1

[0116] Comparative Example 1 is a method for preparing a carbon nanotube reinforced aluminum-based composite material. The main difference from Example 1 is that in the friction extrusion deposition step of Comparative Example 1, the feed rate c of the raw material rod is 36 mm / min, which does not meet the requirement of r 2 ·c=(8~12)·v·t.

[0117] Other steps and parameters are consistent with those in Example 1.

[0118] Figure 6 This is a physical picture of the carbon nanotube reinforced aluminum matrix composite material prepared in Comparative Example 1. Figure 6 It can be seen that the carbon nanotube-reinforced aluminum-based composite material prepared in Comparative Example 1 has defects such as holes and cracks.

[0119] Here, since the friction extrusion deposition processing parameters of Comparative Example 1 do not meet the requirements of 2 ·c=(8~12)·v·t. Due to excessive feeding, the friction between the material and the mold intensifies, the heat generation increases rapidly, the formability decreases, and the material cannot form a complete additive layer, resulting in defects such as holes and cracks in the prepared carbon nanotube-reinforced aluminum-based composite parts.

[0120] Comparative Example 2

[0121] Comparative Example 2 prepares a carbon nanotube-reinforced aluminum-based composite material. The main difference from Example 1 is that in the ball milling step of Comparative Example 1, the volume fraction of the carbon nanotube powder in the composite powder is 4%.

[0122] Other steps and parameters are consistent with those in Example 1.

[0123] Comparative Example 2 Due to the high volume fraction of carbon nanotubes, the plasticity of the material is drastically reduced, the formability is seriously reduced, the forming is difficult during the addition, and the prepared carbon nanotube reinforced aluminum-based composite material has defects such as holes and cracks. Figure 7 shown.

[0124] Comparative Example 3

[0125] Comparative Example 3 prepares a carbon nanotube-reinforced aluminum-based composite material. The main difference from Example 1 is that in the ball milling step of Comparative Example 3, the rotation speed of the ball milling is 300 rpm.

[0126] Other steps and parameters are consistent with those in Example 1.

[0127] Comparative Example 3 Due to the low ball milling speed and poor ball milling effect, the carbon nanotubes are difficult to disperse effectively, and the carbon nanotubes in the obtained carbon nanotube-reinforced aluminum-based composite material are severely agglomerated (such as Figure 8 ), resulting in a decrease in mechanical properties.

[0128] Comparative Example 4

[0129] Comparative Example 4 prepares a carbon nanotube reinforced aluminum-based composite material. The main difference from Example 1 is that the temperature of the hot pressing treatment in Comparative Example 4 is 550°C.

[0130] Other parameters and steps are consistent with those in Example 1.

[0131] Figure 3This is the interface between the carbon nanotubes and the aluminum alloy matrix in the carbon nanotube-reinforced aluminum matrix composite material obtained in Comparative Example 4. Figure 3 It can be seen that carbon nanotubes react with aluminum alloy to generate Al 4 C 3 Harmful phase. This is because the temperature of the hot pressing process is too high, causing the carbon nanotubes to react with the aluminum alloy to generate Al 4 C 3 Harmful appearance.

[0132] Comparative Example 5

[0133] Comparative Example 5 prepares a carbon nanotube reinforced aluminum-based composite material part. The main difference from Example 1 is that during the friction extrusion deposition process, the rotation speed of the friction extrusion deposition mold is 400 rpm.

[0134] Other parameters and steps are consistent with those in Example 1.

[0135] Comparative Example 5 Due to the poor plasticity and formability of the high-strength carbon nanotube reinforced aluminum-based composite material, defects such as holes are generated in the additive part. Specifically, due to the excessively high rotation speed of the friction extrusion deposition mold, the material surface is overheated. When the material rotates and rubs against the mold, the material is carried away by the mold and squeezed out of the mold, resulting in macroscopic defects in the additive part). Fig. 9 shown.

[0136] Comparative Example 6

[0137] Comparative Example 6 prepares a carbon nanotube reinforced aluminum-based composite material component, which is mainly different from Example 1 in that in the heat treatment step, the temperature of the solution treatment is 510°C.

[0138] Other parameters and steps are consistent with those in Example 1.

[0139] The carbon nanotube-reinforced aluminum-based composite material obtained in Comparative Example 6 has overburning defects in its structure due to the excessively high temperature of the solid solution treatment, which affects the performance of the carbon nanotube-reinforced aluminum-based composite material.

[0140] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. A method for additively preparing a carbon nanotube reinforced aluminum-based composite material part, characterized in that: The additive manufacturing method comprises the following steps: Ball milling: ball milling Al-Cu-Mg aluminum alloy powder and carbon nanotube powder to obtain composite powder; Molding and processing: molding and processing the composite powder to obtain a raw material part; Friction extrusion deposition process: the raw material is subjected to friction extrusion deposition process to obtain an additive part; wherein the parameters of the friction extrusion deposition process are controlled as follows: 2 c = (8-12) v t; t is the thickness of a single layer in the additive layer, in mm; c is the feed rate of the raw material, in mm / min; v is the additive advance rate, in mm / min; r is the radius of the raw material, in mm; Heat treatment: heat treatment is performed on the additive component to obtain a carbon nanotube reinforced aluminum-based composite component.

2. The additive manufacturing method for carbon nanotube reinforced aluminum-based composite material parts according to claim 1, characterized in that: The particle size of the Al-Cu-Mg aluminum alloy powder is 5-40 microns.

3. The additive manufacturing method of carbon nanotube reinforced aluminum-based composite material according to claim 1, characterized in that: Calculated in mass percentage, the chemical composition of the Al-Cu-Mg aluminum alloy powder includes: Cu 3.8-4.9%, Mg 1.2-1.8%, and the balance is Al.

4. The additive manufacturing method of carbon nanotube reinforced aluminum-based composite material according to claim 1, characterized in that: In the carbon nanotube powder, the carbon nanotube has a length of 1-20 micrometers and a diameter of 10-30 nanometers.

5. The additive manufacturing method of carbon nanotube reinforced aluminum-based composite material according to claim 1, characterized in that: In the composite powder, the volume fraction of the carbon nanotube powder is 0.5-3%.

6. The additive manufacturing method of carbon nanotube reinforced aluminum-based composite material according to claim 1, characterized in that: In the step of ball milling: The rotation speed of the ball milling treatment is 350-420 rpm; the time of the ball milling treatment is 8-12 hours; iron balls or zirconium oxide balls are used as grinding balls during the ball milling treatment; during the ball milling treatment, the ball-to-powder ratio is 8:1-12:

1.

7. The additive manufacturing method of carbon nanotube reinforced aluminum-based composite material according to claim 1, characterized in that: The steps of forming and processing include: Step 1), hot pressing the composite powder to obtain a prefabricated blank; wherein the temperature of the hot pressing treatment is 400-500°C; Step 2) mechanically processing the prefabricated blank to obtain the raw material part.

8. The additive manufacturing method of carbon nanotube reinforced aluminum-based composite material according to claim 1, characterized in that: The radius of the raw material piece is 5-15 mm.

9. The additive manufacturing method of carbon nanotube reinforced aluminum-based composite material according to claim 1, characterized in that: The raw material is a bar.

10. The additive manufacturing method of carbon nanotube reinforced aluminum-based composite material according to claim 1, characterized in that: In the steps of the friction extrusion deposition process: Feeding a raw material into a friction extrusion deposition mold, the raw material rubs against the rotating friction extrusion deposition mold to partially soften the raw material; wherein the softened raw material is extruded through an extrusion hole of the friction extrusion deposition mold, and forms an additive layer on a substrate as the friction extrusion deposition mold moves; after the friction extrusion deposition process is completed, an additive part is obtained; The rotation speed of the friction extrusion deposition mold is 300-350 rpm, the feed rate of the raw material is 10-500 mm / min, the additive advance rate is 50-3000 mm / min, and the thickness of a single layer in the additive layer is 0.5-4 mm.

11. The additive manufacturing method of carbon nanotube reinforced aluminum-based composite material according to claim 10, characterized in that: In the steps of the friction extrusion deposition process: The substrate is made of Al-Cu-Mg aluminum alloy.

12. The additive manufacturing method of carbon nanotube reinforced aluminum-based composite material according to claim 10, characterized in that: In the steps of the friction extrusion deposition process: The thickness of the substrate is at least 5 mm.

13. The additive manufacturing method of carbon nanotube reinforced aluminum-based composite material according to any one of claims 1 to 12, characterized in that: In the heat treatment step: Solution treatment, performing solution treatment on the additive component to obtain the additive component after solution treatment; Natural aging treatment is performed on the additive component after the solid solution treatment to obtain a carbon nanotube reinforced aluminum-based composite material component.

14. The additive manufacturing method of carbon nanotube reinforced aluminum-based composite material according to claim 13, characterized in that: In the step of solution treatment, the additive part is subjected to a heat preservation treatment at a temperature of 490-500° C. and then quenched to obtain the additive part after the solution treatment; wherein the heat preservation treatment time is 1-2 hours.

15. The additive manufacturing method of carbon nanotube reinforced aluminum-based composite material according to claim 13, characterized in that: In the step of natural aging treatment, the time of the natural aging treatment is at least 96 hours.

16. The additive manufacturing method of carbon nanotube reinforced aluminum-based composite material according to claim 13, characterized in that: After the natural aging treatment, the substrate and / or excess material on the additive component needs to be removed to obtain a carbon nanotube reinforced aluminum-based composite component.

17. A carbon nanotube reinforced aluminum-based composite material, characterized in that: The carbon nanotube reinforced aluminum-based composite material component is prepared by the additive preparation method of the carbon nanotube reinforced aluminum-based composite material component according to any one of claims 1 to 16.

18. The carbon nanotube reinforced aluminum-based composite material member according to claim 17, characterized in that: In the microstructure of the carbon nanotube reinforced aluminum-based composite material, the grain size is 0.3-2 microns; copper-magnesium atomic clusters are dispersed in the grains, wherein the size of the copper-magnesium atomic clusters is ≤20nm; carbon nanotubes are distributed inside the grains and at the grain boundaries; and no harmful phase Al4C3 exists in the microstructure.

19. The carbon nanotube reinforced aluminum-based composite material according to claim 17, characterized in that: The average tensile strength of the carbon nanotube reinforced aluminum-based composite material component is ≥500MPa.

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