Continuous fiber reinforced metal matrix composite material and additive manufacturing method thereof

Abstract

The invention relates to a continuous fiber reinforced metal-based composite material and an additive manufacturing method thereof, belongs to the technical field of additive manufacturing, and solves the problems that in the prior art, the continuous fiber reinforced metal-based composite material is difficult to realize 3D printing, and the integrity and consistency of fibers and / or poor infiltration of the fibers and a matrix are / is solved. An additive manufacturing method of a continuous fiber reinforced metal matrix composite comprises the steps that S1, a three-dimensional model of a laminated composite product is established, slicing treatment is conducted, and each layer of two-dimensional fiber fabric is contained in the corresponding slice; s2, prefabricating a two-dimensional fiber fabric in a layered manner; and S3, additive manufacturing of the laminated composite material product is conducted through a selective laser melting forming method. Rapid additive manufacturing of the continuous fiber reinforced metal-based composite material is achieved, fibers in the obtained continuous fiber reinforced metal-based composite material and a product of the continuous fiber reinforced metal-based composite material have good integrity, consistency and stability, infiltration of the fibers and a matrix is good, and the interface bonding strength is high.

Description

Technical Field

[0001] The present invention relates to the technical field of additive manufacturing, and in particular to a continuous fiber reinforced metal matrix composite material and an additive manufacturing method thereof. Background Art

[0002] In the 1960s, as traditional metal materials could no longer meet the development needs of high-performance weapons and aviation technology, people began to accelerate the research on new materials, which eventually led to the emergence and development of metal-based composite materials. Compared with traditional resin-based composite materials, continuous fiber-reinforced metal-based composite materials not only have the characteristics of high specific strength, high specific modulus, and low expansion coefficient, but also show good high temperature resistance, anti-aging, high thermal conductivity, high electrical conductivity, and radiation resistance, flame retardancy, no moisture absorption, no outgassing, and good dimensional stability. They are widely used in aviation, aerospace and other fields that have high requirements for material performance and harsh material use environments.

[0003] The traditional forming processes of fiber-reinforced metal composites are mainly divided into two categories: liquid method and solid method. The liquid method is mainly a method of compounding a metal matrix in a molten state with solid fibers under no pressure or high pressure; the solid method is mainly a method of mixing and arranging metal powder or metal foil with fibers in a certain content, distribution, and direction according to design requirements, and then pressurizing and heating to composite and bond the metal matrix with the fiber reinforcement; the above traditional forming processes are complicated, with many manual and semi-automatic processes, long mold development cycle, and high manufacturing cost; in addition, since the liquid method requires long-term high-temperature immersion, the fiber / metal interface reaction is difficult to control, which can easily lead to a decrease in fiber performance or even failure. The solid method also has problems such as difficult uniform fiber distribution, poor interface bonding, and easy cracking.

[0004] Additive manufacturing (also known as 3D printing) is a manufacturing method that accumulates materials layer by layer from the bottom up, which can achieve rapid manufacturing of parts. However, most of the existing additive manufacturing of continuous fiber reinforced composite materials use thermosetting and thermoplastic resins as the matrix, and there are very few reports on additive manufacturing of metal matrix composites. Therefore, finding an additive manufacturing method for continuous fiber reinforced metal matrix composites is of great significance for solving key problems in the molding of continuous fiber reinforced metal matrix composites (for example: rapid manufacturing of complex structures, uniformity, stability, integrity, consistency of continuous fibers, and wetting and interface bonding strength between fibers and matrix). Summary of the invention

[0005] In view of the above analysis, the present invention aims to provide a continuous fiber reinforced metal matrix composite material and an additive manufacturing method thereof to solve at least one of the following technical problems: in the prior art, continuous fiber reinforced metal matrix composite materials are difficult to achieve 3D printing, and there are problems with fiber uniformity, integrity, consistency and / or poor wetting between fiber and matrix.

[0006] The objective of the present invention is achieved through the following technical solutions:

[0007] In a first aspect, the present invention provides an additive manufacturing method for a continuous fiber reinforced metal matrix composite material, wherein the composite material is a laminated composite material, comprising a metal matrix and a two-dimensional fiber fabric woven from continuous fibers and distributed in an XY plane;

[0008] The additive manufacturing method comprises the following steps:

[0009] Step S1, establishing a three-dimensional model of a laminated composite material product, and performing slicing processing, wherein each layer of two-dimensional fiber fabric is included in a corresponding slice;

[0010] Step S2, prefabricating two-dimensional fiber fabrics in layers: using a hot melt rolling prepreg method to fully infiltrate the two-dimensional fiber fabrics with molten metal liquid and shape them, and preform them into a two-dimensional fiber preform that can be shaped; processing the two-dimensional fiber preform into a two-dimensional fiber preform of a required shape, and stacking them in the order of slice printing for standby;

[0011] Step S3, additive manufacturing of laminated composite products by laser selective melting: when printing a certain layer of slices containing two-dimensional fiber fabrics, first accurately lay out the two-dimensional fiber preforms in the corresponding order, position them, and then lay out or spray the metal matrix.

[0012] Optionally, in step S2, the fibers used to prepare the two-dimensional fiber fabric are ultra-small tow fibers of 0.1K to 0.8K.

[0013] Furthermore, in step S2, the main steps of the hot melt rolling prepreg method include: immersing the two-dimensional fiber fabric in molten metal liquid, fully infiltrating, combining and compacting the two-dimensional fiber fabric and the metal liquid through rolling, and obtaining a two-dimensional fiber preform after cooling at room temperature.

[0014] Furthermore, in step S2, the main steps of the rolling method include: the two-dimensional fiber fabric fully soaked in the metal liquid is squeezed by a pair of rotating pressure rollers, so that the two-dimensional fiber fabric passing through the rollers is deformed into a two-dimensional fiber preform with a certain shape and stiffness under this action.

[0015] Furthermore, in step S2, the type of the metal liquid used to impregnate the two-dimensional fiber fabric in the hot melt rolling prepreg method is the same as the type of the metal matrix.

[0016] Optionally, types of metal substrates include but are not limited to aluminum-based, magnesium-based, zinc-based, nickel-based, titanium-based, iron-based, copper-based, cobalt-chromium alloys, and the like.

[0017] Furthermore, in step S2, a cutting process is used to process the two-dimensional fiber preform into a two-dimensional fiber preform of a desired shape, and the cutting process includes but is not limited to an automatic cutting method and a laser cutting method.

[0018] Further, step S3 includes:

[0019] Step S321: When printing a certain layer of slices containing fibers, the robot automatically picks up the two-dimensional fiber preform of the current layer, and accurately positions and places it through infrared scanning. After placing the two-dimensional fiber preform of the current layer, the laser is used to scan W points on the two-dimensional fiber preform for melting and positioning; W ≥ 3, and not on a straight line;

[0020] Step S322: The powder feeding cylinder delivers a certain amount of metal powder, which is spread onto the working platform by the powder spreading roller and the scraper;

[0021] Step S323: Scanning the current layer with laser, and completing the laser selective melting molding of the current layer by melting and solidifying the scanned metal powder;

[0022] Step S324: After the scanning is completed, the working platform descends by a layer and continues to print the next layer;

[0023] Repeat steps S321 to S324, or steps S322 to S324, until the last layer of slices is printed; and obtain a metal-based composite material product.

[0024] Furthermore, in step S3, before 3D printing, the substrate is mounted on the working platform of the molding cavity; and / or during the 3D printing process, the molding cavity is evacuated and an inert protective gas is introduced.

[0025] In a second aspect, the present invention provides a continuous fiber reinforced metal matrix composite material and a product thereof obtained according to the additive manufacturing method of the continuous fiber reinforced metal matrix composite material.

[0026] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0027] 1. The present invention provides an additive manufacturing method for continuous fiber reinforced metal matrix composite materials. The method of combining "layered prefabricated two-dimensional fiber fabrics" with "metal material additive manufacturing process" is used to achieve rapid additive manufacturing of continuous fiber reinforced metal matrix composite material structures, thereby greatly expanding the design freedom of continuous fiber reinforced metal matrix composite material structures, making full use of the advantages of additive manufacturing, and being able to quickly design and produce highly complex and diversified products without molds.

[0028] 2. The additive manufacturing method of continuous fiber reinforced metal matrix composite materials provided by the present invention adopts the method of "layered prefabricated two-dimensional fiber fabric" combined with "metal material additive manufacturing process", so that continuous fiber reinforced metal matrix composite materials can be rapidly additively manufactured. Compared with the existing liquid method and solid method, the mold processing link can be omitted, the flexibility of structural design can be maximized, and high-complexity and diversified continuous fiber reinforced metal matrix composite materials and their products can be rapidly designed and produced; at the same time, the manufacturing method of the present invention adopts simple and efficient process steps to obtain products with very good process quality and performance; among them, since the metal matrix and fiber in the "layered prefabricated two-dimensional fiber fabric" have been fully infiltrated, combined and shaped, and there is no need to impregnate the fiber at high temperature for a long time during the whole process, the uniformity, stability, integrity and consistency of the two-dimensional fiber fabric in the continuous fiber reinforced metal matrix composite materials and their products are better, which can meet the mechanical properties and functional requirements of high-performance metal matrix composite materials and their products.

[0029] 3. An embodiment of the present invention provides an additive manufacturing method for a continuous carbon fiber reinforced aluminum alloy composite tensile test piece, which adopts "layered prefabricated two-dimensional fiber fabric" combined with an additive manufacturing process (i.e., laser selective melting molding) for integrated molding, thereby realizing the rapid design and manufacturing of continuous carbon fiber reinforced aluminum alloy composite materials, and preparing continuous fiber reinforced metal matrix composite materials and their products with better mechanical properties than pure metal materials with the most economical raw materials; since the carbon fibers and the molten metal liquid (preferably the same as the metal matrix) in the "layered prefabricated two-dimensional fiber fabric" have been fully infiltrated, combined and shaped, the carbon fiber two-dimensional fabric has good uniformity, stability, integrity and consistency in the matrix, and the tensile strength of the tensile test piece finally obtained is increased by more than 20% compared with that of pure aluminum alloy.

[0030] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0032] Figure 1 A schematic diagram of a laminated composite material provided by an embodiment of the present invention;

[0033] Figure 2 A schematic diagram of a tensile test piece in the Z direction provided by an embodiment of the present invention;

[0034] Figure 3 for Figure 2 AA cross-sectional diagram of ;

[0035] Figure 4 is a cross-sectional view of a slice of a layer of a two-dimensional fiber fabric in a tensile test piece provided by an embodiment of the present invention;

[0036] Reference numerals:

[0037] 101-Z-direction section including fibers and matrix; 102-section of XY plane, i.e., the plane where the two-dimensional fiber fabric is located; 701-tensile test piece; 702-reinforcement sheet; 703-carbon fiber two-dimensional fabric; A-first positioning point; B-second positioning point; C-third positioning point; D-fourth positioning point. DETAILED DESCRIPTION

[0038] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0039] The present invention provides an additive manufacturing method for a continuous fiber reinforced metal matrix composite material. The composite material is a laminated composite material, comprising a metal matrix and a two-dimensional fiber fabric woven from continuous fibers and distributed in an XY plane.

[0040] It should be noted that the type of metal matrix can be selected as needed, including but not limited to aluminum-based, magnesium-based, zinc-based, nickel-based, titanium-based, iron-based, copper-based, cobalt-chromium alloy, etc.

[0041] The additive manufacturing method comprises the following steps:

[0042] Step S1: Establish a three-dimensional model of a laminated composite material product and perform slicing processing, wherein each layer of two-dimensional fiber fabric is included in a corresponding slice.

[0043] Step S1 specifically includes the following steps:

[0044] Step S11: using computer-aided design software to establish a three-dimensional model of the laminated composite material product;

[0045] Specifically, in the established three-dimensional model, the two-dimensional fiber fabric in the laminated composite product is distributed in the XY plane and accumulated in multiple layers. There is no fiber in the product along the Z direction perpendicular to the XY plane. The XY plane is also the base plane for future additive manufacturing. For example, refer to Figure 1 , 101 is the Z-direction section including the fiber and the matrix. Because there is no Z-direction fiber, what can be seen in the Z-direction section is the fiber cross section and the matrix cross section. 102 is the section of the XY plane. Since the fibers are distributed in the XY plane, the fiber distribution of the two-dimensional fabric can be seen.

[0046] Optionally, the thickness of each layer of two-dimensional fiber fabric in the laminated composite material product is less than 0.5 mm. Preferably, the thickness of each layer of two-dimensional fiber fabric is less than 0.1 mm.

[0047] It should be noted that the surface of the laminated composite material product is a matrix material that does not contain fibers; such a setting can ensure that the surface of the laminated composite material product is completely flat, and the fiber fabric can be fully covered in the product shape to ensure that no fibers are exposed on the product surface after molding.

[0048] Preferably, the thickness of the matrix material (excluding fibers) of the laminated composite product along the Z-upward and lower surfaces is not less than 0.1 mm; more preferably, the thickness of the matrix material (excluding fibers) of the laminated composite product along the Z-upward and lower surfaces is not less than 0.5 mm.

[0049] Preferably, the outer contour of each layer of two-dimensional fiber fabric distributed in the XY plane of the laminated composite material product is 0.1 mm to 0.3 mm smaller than the outer contour of the product.

[0050] It should be noted that the number of layers of the two-dimensional fiber fabric can be selected as needed, and the number of layers is a natural number greater than or equal to 2; further, the material, thickness and fiber arrangement of each layer of the two-dimensional fiber fabric can be the same or different;

[0051] In a possible design, each layer of the two-dimensional fiber fabric has the same material, thickness, and fiber arrangement.

[0052] In one possible design, each layer of the two-dimensional fiber fabric has the same material and thickness, but the fiber arrangement is different.

[0053] It should be noted that the distribution of the two-dimensional fiber fabric in the matrix can be selected as needed. For example, two or more layers of two-dimensional fiber fabric are evenly or non-evenly stacked layer by layer in the matrix along a plane perpendicular to the Z direction.

[0054] Optionally, computer-aided design (CAD) software can be selected as needed, including but not limited to AutoCAD, Autodesk Inventor, SolidWorks, CATIA, Pro / E, UG NX, SolidEdge, Onespace, etc.

[0055] Step S12: convert the three-dimensional model of the laminated composite product into an STL triangulated file, set the XY plane where the two-dimensional fiber fabric is located as the base plane of 3D printing, set the Z direction perpendicular to the XY plane as the layer-by-layer stacking direction, and slice the STL triangulated file.

[0056] Specifically, the three-dimensional model of the laminated composite product established in step S11 is converted into the STL triangulated file required by the additive manufacturing system, the XY plane of the laminated composite product (that is, the plane where each layer of two-dimensional fiber fabric is located) is determined as the base plane of 3D printing, and the Z direction perpendicular to the XY plane is set as the layer-by-layer stacking direction. The STL triangulated file is sliced ​​to realize the conversion of the three-dimensional model into a two-dimensional thin film model.

[0057] It should be noted that when slicing, it is necessary to ensure that each layer of the two-dimensional fiber fabric is contained in the corresponding slice, that is, the substrate of each slice thickness completely wraps the two-dimensional fiber fabric of this layer, so that the surface is flat after laying each layer of substrate material to ensure smooth subsequent printing operations, for example, the scraper motion system can move smoothly to lay each layer of printing material;

[0058] In order to meet the above requirements, the slice thickness is greater than the thickness of the two-dimensional fiber fabric; optionally, the thickness of each layer of the two-dimensional fiber fabric can be the same or different, and the maximum thickness in the two-dimensional fiber fabric is set as M1, satisfying N>M1, N is the slice thickness, and M1 is the maximum thickness in the two-dimensional fiber fabric. Optionally, N is 0.025mm~0.5mm; preferably, N is 0.05mm~0.1mm; illustratively, M1=0.08mm, N=0.1mm.

[0059] It should be noted that the first and last layers of the slice are matrix materials that do not contain fibers, satisfying N<S, where N is the slice thickness, and S is the thickness of the matrix material (i.e., does not contain fibers) on the upper and lower surfaces of the laminated composite product along the Z direction; optionally, N is 0.025mm~0.5mm; preferably, N is 0.05mm~0.1mm; exemplarily, S=0.6mm, N=0.1mm.

[0060] It can be seen that the slice thickness N is selected according to the thickness of the two-dimensional fiber fabric and the thickness of the matrix material on the upper and lower surfaces of the product along the Z direction, ensuring that each layer of the two-dimensional fiber fabric is contained in the corresponding slice, and the first and last layers of the slice are matrix materials that do not contain fibers, so as to ensure the smooth progress of subsequent printing operations, and that the fiber fabric can be fully covered in the shape of the product after molding, ensuring that the surface of the laminated composite product is completely flat.

[0061] In one possible design, after converting the 3D model into an STL file, support can be generated by software at the bottom of the 3D model or at a location with a large slope, and the 3D model and support can be sliced ​​and imported into the 3D printing system control host together. The support here is mainly a temporary structure added to maintain the shape and stability of the printed object, which can be easily removed after printing.

[0062] Step S2, prefabricating two-dimensional fiber fabrics in layers: first prepare two-dimensional fiber fabrics, and use hot melt rolling prepreg method to fully infiltrate the two-dimensional fiber fabrics with molten metal liquid and shape them, and preform them into two-dimensional fiber preforms; process the two-dimensional fiber preforms into two-dimensional fiber preforms of the required shape, and stack them in the order of slice printing for use.

[0063] Step S21: preparing a two-dimensional fiber fabric by weaving;

[0064] Specifically, a plurality of fiber bundles are regularly interlocked alternately by weaving to form a two-dimensional fiber fabric. The weaving method of the two-dimensional fiber fabric can be selected according to needs, including but not limited to weaving, braiding, knitting, etc.

[0065] It should be noted that the diameter of the fiber bundle used to prepare the two-dimensional fiber fabric is determined according to the slice thickness in step S1 to satisfy N>M1, where N is the slice thickness and M1 is the maximum thickness of the two-dimensional fiber fabric.

[0066] In a possible design, the slice thickness N is 0.05 mm to 0.1 mm. To satisfy N>M1, preferably, the fiber used to prepare the two-dimensional fiber fabric is an ultra-small tow fiber, and the ultra-small tow is a fiber not larger than 1K, where 1K means that a bundle of fiber contains 1000 single filaments; more preferably, the fiber used to prepare the two-dimensional fiber fabric is an ultra-small tow fiber of 0.1K to 0.8K;

[0067] For example, the slice thickness N=0.1 mm, the fiber bundle is 0.12K (each bundle has 120 fiber filaments), and the diameter of the filament is 8 μm, which can ensure that the thickness of the prepared two-dimensional fiber fabric is less than 0.1 mm.

[0068] Optionally, the fiber type for preparing the two-dimensional fiber fabric can be selected as needed, including but not limited to one or a combination of silicon carbide fiber, carbon fiber, silicon nitride fiber, boron fiber, basalt fiber, glass fiber, aramid fiber, and alumina (including mullite) fiber.

[0069] Optionally, the fiber arrangement of the two-dimensional fiber fabric can be selected according to needs (for example, the direction of force on the product, etc.), including but not limited to unidirectional fabric, plain fabric, twill fabric, etc. For example, the unidirectional fabric is a thinner two-dimensional fiber fabric in which the fibers are subjected to force in the main direction by evenly laying a large number of fiber filaments along a main direction and weaving the fiber filaments in the main direction together with fewer fiber filaments; see Figure 4 The two-dimensional fiber fabric corresponding to the slice adopts the shape of a unidirectional cloth. The fibers in the two-dimensional fiber fabric are mainly distributed along the X direction, and a smaller amount of fibers are distributed along the Y direction, which plays a role in linking and fixing the X-direction fibers.

[0070] Step S22: The two-dimensional fiber fabric is fully infiltrated with molten metal liquid and shaped by hot melt rolling prepreg method to form a two-dimensional fiber preform that can be shaped so as to maintain the existing shape when picked up and placed.

[0071] It should be noted that the main steps of the hot melt rolling prepreg method include: immersing the two-dimensional fiber fabric in molten metal liquid, fully infiltrating, combining and compacting the two-dimensional fiber fabric and the metal liquid through rolling, and obtaining a two-dimensional fiber preform after cooling at room temperature.

[0072] Among them, the main steps of the rolling method include: using a pair of rotating pressure rollers to squeeze the two-dimensional fiber fabric that is fully soaked in metal liquid, so that the two-dimensional fiber fabric passing through the rollers is deformed into a two-dimensional fiber preform with a certain shape and stiffness under this action.

[0073] Preferably, the type of the metal liquid used to impregnate the two-dimensional fiber fabric in the hot melt rolling prepreg method is the same as the type of the metal matrix, so that during the 3D printing process, the metal in the two-dimensional fiber preform and the matrix metal can be well compatible and infiltrated with each other and then firmly combined together, so that the interface bonding force between the two-dimensional fiber preform and the metal matrix is ​​stronger. Exemplarily, if the matrix is ​​selected as aluminum alloy, the metal liquid used to impregnate the two-dimensional fiber fabric in the hot melt rolling prepreg method is also selected as aluminum alloy. Due to the similar molecular structure, metals of the same type are more easily combined together when heated by the laser beam during the 3D printing process, thereby improving the interface bonding strength.

[0074] It should be noted that in order to ensure the smooth progress of 3D printing, the thickness of the two-dimensional fiber preform is less than the slice thickness, satisfying M1≤M2<N, M1 is the maximum thickness of the two-dimensional fiber fabric, M2 is the maximum thickness of the two-dimensional fiber preform, and N is the slice thickness; optionally, N is 0.025mm~0.5mm; preferably, N is 0.05mm~0.1mm.

[0075] It is worth noting that the two-dimensional fiber fabric preform obtained by pre-treating the two-dimensional fiber fabric with the hot melt rolling prepreg method has good rigidity and can maintain the existing shape of the two-dimensional fiber fabric during the pick-up and placement operations. At the same time, the hot melt rolling prepreg method allows the two-dimensional fiber and the metal liquid to be fully infiltrated, combined and shaped, which can well maintain the uniformity, stability, integrity and consistency of the two-dimensional fiber fabric in the subsequent 3D printing process and the final product.

[0076] Step S23: Processing the two-dimensional fiber preform into a two-dimensional fiber preform of a required shape, and stacking them in the order of slice printing for standby use.

[0077] Specifically, the two-dimensional fiber preform is processed into a two-dimensional fiber preform of a desired shape by a cutting process, and the number of layers and the outer contour of the two-dimensional fiber preform are determined according to the two-dimensional fiber fabric in the three-dimensional model of the laminated composite product established in step S1. For example, if four layers of two-dimensional fiber fabric are arranged at the 200th, 300th, 400th, and 500th layers in the three-dimensional model, four two-dimensional fiber preforms are cut out according to the outer contour of the corresponding slice layer, and the plane size of each two-dimensional fiber preform is slightly smaller than the plane size of the slice where the corresponding two-dimensional fiber preform is located, so as to ensure that no fiber is exposed on the surface of the product after molding.

[0078] Optionally, the cutting process can be selected as needed, including but not limited to automatic cutting, laser cutting, etc. Exemplarily, the automatic cutting method can use a CNC cutting machine to cut the two-dimensional fiber preform to obtain a two-dimensional fiber preform of a desired shape.

[0079] Step S3: Additive manufacturing of metal-based composite materials by laser selective melting: When printing a slice layer containing a two-dimensional fiber fabric, first accurately lay out the two-dimensional fiber preforms in the corresponding order, position them, and then lay out or spray the metal matrix.

[0080] It should be noted that the main steps of accurately laying out the two-dimensional fiber preforms in the corresponding order include: before laying out or spraying a certain layer of the matrix, accurately locating the placement position of the two-dimensional fiber preforms of the corresponding layer of the matrix to be sprayed by infrared scanning, and laying them on the printed previous layer. Exemplarily, before laying out or spraying a certain layer of the matrix, the two-dimensional fiber preforms of the corresponding layer are automatically picked up by a robot, and the placement position of the two-dimensional fiber preforms of the corresponding layer of the matrix to be sprayed is accurately located by infrared scanning, and laid on the printed previous layer.

[0081] It should be noted that the main steps of the positioning include: after accurately placing the two-dimensional fiber preform of the corresponding layer, selecting W positioning points on the two-dimensional fiber preform, and using laser scanning to perform melting positioning on the positioning points (the metal at the positioning points is heated by the laser to melt and then cooled and solidified), similar to the mechanism of metal spot welding, so that the two-dimensional fiber preform is fixed on the previous printed layer to ensure that the two-dimensional fiber preform will not move when the metal matrix of the corresponding layer is placed later.

[0082] Preferably, the number of positioning points W is ≥ 3, and they are not on a straight line to better ensure effective positioning.

[0083] Specifically, step S3 includes the following steps:

[0084] Step S31: preparing metal powder;

[0085] Procurement of metal powders for 3D printing;

[0086] It should be noted that the type of metal powder can be selected as needed, including but not limited to aluminum-based, magnesium-based, zinc-based, nickel-based, titanium-based, iron-based, copper-based, cobalt-chromium alloy, etc.

[0087] Step S32: laser selective melting forming;

[0088] The STL data file generated in step S1 is imported into the 3D printer system, and the metal powder prepared in step S31 is placed in the material tank of the 3D printer for laser selective melting printing.

[0089] The printing equipment and specific process parameters of the laser selective melting molding can be selected and set from the parameters of the 3D printer and 3D printing molding technology in the prior art.

[0090] In one possible design, step S32 includes the following steps:

[0091] Step S321: when printing a certain layer of slices containing fibers, the robot automatically picks up the two-dimensional fiber preform of the current layer, and accurately positions and places it by infrared scanning. After placing the two-dimensional fiber preform of the current layer, laser scans W points on the two-dimensional fiber preform for melting positioning; W ≥ 3, and not on a straight line;

[0092] Step S322: The powder feeding cylinder delivers a certain amount of metal powder, which is spread onto the working platform by the powder spreading roller and the scraper;

[0093] Step S323: Scanning the current layer with laser, and completing the laser selective melting molding of the current layer by melting and solidifying the scanned metal powder;

[0094] Step S324: After the scanning is completed, the working platform descends by a layer and continues to print the next layer;

[0095] When printing a slice layer containing fibers, the printing is performed according to the above steps S321 to S324; when printing a slice layer not containing fibers, the printing is performed according to steps S322 to S324;

[0096] Repeat steps S321 to S324, or steps S322 to S324, until the last layer of slices is printed; and obtain a metal-based composite material product.

[0097] Preferably, the printed metal-based composite material product is taken out, and is sandblasted or treated with high-pressure gas to remove residual powder on the surface and inside of the product and clean it.

[0098] In one possible design, before 3D printing, a substrate is installed on the working platform of the molding cavity to provide a growth plane for the metal powder, facilitate the smooth removal of the formed parts, and provide a heat dissipation base for the high-temperature melting process of the metal powder.

[0099] In one possible design, during the 3D printing process, the molding cavity is evacuated and an inert protective gas, such as argon or nitrogen, is introduced to seal the molding cavity to prevent oxidation reactions during the high-temperature melting of the metal powder.

[0100] The present invention also provides a continuous fiber reinforced metal matrix composite material and its products obtained according to the additive manufacturing method of the continuous fiber reinforced metal matrix composite material, comprising a metal matrix and a two-dimensional fiber fabric woven from continuous fibers and distributed in the XY plane. It is understood that the two-dimensional fiber fabric is stacked layer by layer along the Z direction (i.e., the 3D printing stacking direction) perpendicular to the XY plane.

[0101] It should be noted that the type of metal matrix can be selected as needed, including but not limited to aluminum-based, magnesium-based, zinc-based, nickel-based, titanium-based, iron-based, copper-based, cobalt-chromium alloy, etc.

[0102] The fiber type of the two-dimensional fiber fabric can be selected as needed, including but not limited to one or a combination of silicon carbide fiber, carbon fiber, silicon nitride fiber, boron fiber, basalt fiber, glass fiber, aramid fiber, and alumina (including mullite) fiber.

[0103] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments.

[0104] Embodiment 1:

[0105] This embodiment provides an additive manufacturing method for a continuous carbon fiber reinforced aluminum alloy composite tensile test piece.

[0106] The size and structure of the tensile test piece are in accordance with the mechanical properties test standard GB3354-2014, such as Figure 2 and Figure 3 As shown, four reinforcing sheets 702 are attached to the clamped parts at both ends of the tensile test piece 701 for protection to prevent the huge clamping force during the tensile test from damaging the test piece itself. The tensile test piece 701 is formed by 3D printing, and the reinforcing sheet 702 is formed by traditional machining, and then the reinforcing sheet 702 and the tensile test piece 701 are firmly bonded together by a bonding process. Among them, the tensile test piece 701 includes an aluminum alloy matrix and a two-dimensional fiber fabric distributed in the XY plane (that is, the two-dimensional fiber fabric is stacked layer by layer along the Z direction perpendicular to the XY plane). The material of the tensile test piece 701 is a continuous carbon fiber reinforced aluminum alloy composite material.

[0107] The additive manufacturing method of the tensile test piece 701 comprises the following steps:

[0108] Step S1: using UG (Unigraphics NX) software to design and model, forming a three-dimensional model of the tensile test piece; converting the three-dimensional model of the tensile test piece into an STL triangulated file required by the additive manufacturing system, setting the slice thickness to 0.1 mm, determining the XY plane of the tensile test piece (that is, the plane where each layer of two-dimensional fiber fabric is located) as the base plane of 3D printing, setting the Z direction perpendicular to the XY plane as the layer-by-layer stacking direction, and performing a slice operation on the three-dimensional model; Figure 4 Cross-sectional view showing a slice through a layer of a 2D fiber fabric contained in a tensile test piece.

[0109] The main dimensions of the tensile test piece 701 include: total length of 200mm, effective test section length of 55mm, effective test section width of 10mm, test piece thickness (i.e., Z-direction dimension) of 4mm; according to the Z-direction dimension of 4mm, the slice thickness is 0.1mm, and the total number of slices is 40 layers. In this embodiment, a total of 38 layers of two-dimensional fiber fabrics are provided, and the positions of these 38 layers of fabrics in the Z direction are respectively located at the 2nd layer, 3rd layer, 4th layer, ... 38th layer, and 39th layer of the printed slices, ensuring that the outer contour size of each layer of two-dimensional fiber fabric is 0.2mm smaller than the outer edge of the product of the corresponding layer of slices, so that each layer of carbon fiber two-dimensional fabric can be fully covered in the corresponding slice shape.

[0110] Step S2, prefabricating two-dimensional fiber fabrics in layers;

[0111] Step S21: Select a fiber tow 1K (each tow has 1000 carbon fiber filaments), a T800 carbon fiber with a filament diameter of 5 μm, and prepare a two-dimensional carbon fiber fabric by weaving, ensuring that the thickness of the obtained carbon fiber two-dimensional fabric is less than 0.1 mm; Figure 4 As shown, the fibers in the two-dimensional fabric are mainly distributed along the X direction, and a smaller amount of fibers are distributed along the Y direction, which plays a role in linking and fixing the X-direction fibers; this arrangement is mainly considered to be the main force direction of the test piece 701 is the tensile direction (ie, the X direction).

[0112] Step S22: Before 3D printing, the carbon fiber two-dimensional fabric is pretreated by hot melt rolling prepreg method. Specifically, the carbon fiber two-dimensional fabric is immersed in molten 7075 aluminum alloy liquid, and then the two-dimensional fabric of the carbon fiber soaked in the 7075 aluminum alloy liquid is squeezed by a rotating pair of rollers through a rolling method to ensure that the carbon fiber and the 7075 aluminum alloy liquid are fully soaked, combined and compacted. After cooling at room temperature, a two-dimensional fiber preform with a certain shape and rigidity is obtained. By controlling the immersion (for example, the temperature of the aluminum alloy, the immersion time) and / or rolling parameters, the thickness of the two-dimensional fiber preform is ensured to be less than 0.1 mm.

[0113] Step S23: Since the slices of the tensile test piece 701 along the Z direction have the same cross-sectional shape, the two-dimensional fiber preform of step S22 is cut by a CNC cutting machine according to the outer contour of any one of the slices. When cutting, ensure that each layer of the two-dimensional fiber fabric is 0.2 mm smaller than the outer contour of the corresponding layer of slices, so as to obtain a 38-layer two-dimensional fiber preform of the required shape.

[0114] Step S31: purchasing 7075 aluminum alloy powder for 3D printing;

[0115] Step S32: laser selective melting forming;

[0116] Import the STL data file generated in step S1 into the 3D printer system, put the 7075 aluminum alloy powder prepared in step S31 into the trough of the 3D printer, and perform 3D printing according to the laser selective melting molding process. The specific steps are as follows:

[0117] Step S321: When printing a certain layer of slices containing carbon fiber, the robot automatically picks up the two-dimensional fiber preform of the current layer and accurately positions and places it through infrared scanning. After placing the two-dimensional fiber preform of the current layer, the laser is used to align four positioning points on the two-dimensional fiber preform (for example, Figure 4 The first positioning point A, the second positioning point B, the third positioning point C, and the fourth positioning point D) located at the four vertices of the rectangle are laser melted and positioned, similar to the mechanism of metal spot welding, so that the two-dimensional fiber preform is fixed on the printed previous layer;

[0118] Step S322: a certain amount of aluminum alloy powder is delivered by a powder delivery cylinder and spread onto a substrate on a workbench by a powder spreading roller and a scraper;

[0119] Step S323: using laser as an energy source, scanning the current layer according to the path planned in the slicing model of step S1, and completing the laser selective melting forming of the current layer by melting and solidifying the scanned aluminum alloy powder;

[0120] Step S324: After the scan is completed, the piston of the forming platform descends by a layer and continues to print the next layer.

[0121] Among them, the first layer (1st layer) and the last layer (40th layer) of the tensile test piece are pure 7075 aluminum alloy layers without fibers, and 3D printing is performed according to steps S322 to S324. The remaining 38 layers are sliced ​​layers containing carbon fiber two-dimensional fabrics. Steps S321 to S324 are repeated for 3D printing until the last layer of slices is printed to obtain the tensile test piece 701.

[0122] Mechanical properties test:

[0123] According to the relevant standards of tensile test (i.e. GB3354-2014), four reinforcing sheets 702 at both ends of the tensile test piece 701 are made by traditional machining process. The material of the reinforcing sheet 702 is 7075 aluminum alloy, the width of the reinforcing sheet 702 is 20 mm, and the thickness of the reinforcing sheet 702 is 1.5 mm. The four reinforcing sheets 702 and the tensile test piece 701 are firmly bonded together by bonding process.

[0124] The T800 continuous carbon fiber reinforced 7075 aluminum alloy composite material tensile test piece (including the reinforcement sheet) obtained in this embodiment was subjected to a tensile test in accordance with the relevant tensile test standard (GB3354-2014). The experimental results showed that the tensile strength of the tensile test piece in this embodiment was increased by more than 20% compared with that of the pure 7075 aluminum alloy test piece.

[0125] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for additive manufacturing of continuous fiber reinforced metal matrix composite materials, characterized in that: The composite material is a laminated composite material, comprising a metal matrix and a two-dimensional fiber fabric woven from continuous fibers and distributed in an XY plane; The additive manufacturing method comprises the following steps: Step S1, establishing a three-dimensional model of a laminated composite material product, and performing slicing processing, wherein each layer of two-dimensional fiber fabric is included in a corresponding slice; Step S2, prefabricating two-dimensional fiber fabrics in layers: using a hot melt rolling prepreg method to fully infiltrate the two-dimensional fiber fabrics with molten metal liquid and shape them, and preform them into a two-dimensional fiber preform that can be shaped; processing the two-dimensional fiber preform into a two-dimensional fiber preform of a required shape, and stacking them in the order of slice printing for standby; Step S3, additive manufacturing of laminated composite products by laser selective melting: when printing a certain layer of slices containing two-dimensional fiber fabrics, first accurately lay out the two-dimensional fiber preforms in the corresponding order, position them, and then lay out or spray the metal matrix.

2. The additive manufacturing method of continuous fiber reinforced metal matrix composite material according to claim 1, characterized in that: In step S2, the fibers used to prepare the two-dimensional fiber fabric are ultra-small tow fibers of 0.1K to 0.8K.

3. The additive manufacturing method of continuous fiber reinforced metal matrix composite material according to claim 1, characterized in that: In step S2, the main steps of the hot melt rolling prepreg method include: immersing the two-dimensional fiber fabric in molten metal liquid, fully infiltrating, combining and compacting the two-dimensional fiber fabric and the metal liquid by rolling, and obtaining a two-dimensional fiber preform after cooling at room temperature.

4. The additive manufacturing method of continuous fiber reinforced metal matrix composite material according to claim 3, characterized in that: In step S2, the main steps of the rolling method include: the two-dimensional fiber fabric fully soaked in the metal liquid is squeezed by a pair of rotating pressure rollers, so that the two-dimensional fiber fabric passing between the rollers is deformed into a two-dimensional fiber preform with a certain shape and stiffness.

5. The additive manufacturing method of continuous fiber reinforced metal matrix composite material according to claim 1, characterized in that: In step S2, the type of the metal liquid used to impregnate the two-dimensional fiber fabric in the hot melt rolling prepreg method is the same as the type of the metal matrix.

6. The additive manufacturing method of continuous fiber reinforced metal matrix composite material according to claim 1, characterized in that: The types of the metal matrix include, but are not limited to, aluminum-based, magnesium-based, zinc-based, nickel-based, titanium-based, iron-based, copper-based, cobalt-chromium alloy, and the like.

7. The additive manufacturing method of continuous fiber reinforced metal matrix composite material according to claim 1, characterized in that: In step S2, a cutting process is used to process the two-dimensional fiber preform into a two-dimensional fiber preform of a desired shape, and the cutting process includes but is not limited to an automatic cutting method and a laser cutting method.

8. The additive manufacturing method of continuous fiber reinforced metal matrix composite material according to claim 1, characterized in that: Step S3 includes: Step S321: when printing a certain layer of slices containing fibers, the robot automatically picks up the two-dimensional fiber preform of the current layer, and accurately positions and places it by infrared scanning. After placing the two-dimensional fiber preform of the current layer, laser scans W points on the two-dimensional fiber preform for melting positioning; W ≥ 3, and not on a straight line; Step S322: The powder feeding cylinder delivers a certain amount of metal powder, which is spread onto the working platform by the powder spreading roller and the scraper; Step S323: Scanning the current layer with laser, and completing the laser selective melting molding of the current layer by melting and solidifying the scanned metal powder; Step S324: After the scanning is completed, the working platform descends by a layer and continues to print the next layer; Repeat steps S321 to S324, or steps S322 to S324, until the last layer of slices is printed; and obtain a metal-based composite material product.

9. The additive manufacturing method of continuous fiber reinforced metal matrix composite material according to claim 8, characterized in that: In step S3, before 3D printing, a substrate is mounted on a working platform of the molding cavity; and / or during 3D printing, the molding cavity is evacuated and an inert protective gas is introduced.

10. A continuous fiber reinforced metal matrix composite material and a product thereof obtained by the additive manufacturing method of a continuous fiber reinforced metal matrix composite material according to any one of claims 1 to 9.

Images