Bionic composite material and multistage auxiliary directional preparation method thereof

Abstract

The invention discloses a bionic composite material which is composed of a metal matrix phase and a second phase with microscopic preferred orientation, the volume fraction of the second phase is 2%-40%, and the second phase is directionally arranged to form a shell-like structure; the bionic composite material is prepared by a multi-stage auxiliary orientation method which comprises the following steps: 1, preliminarily orienting raw material powder of a second phase by a physical method; 2, optimizing a second-phase directional structure through pressing and sintering processes; and thirdly, the second-phase orientation effect is further strengthened through a plastic deformation process. According to the bionic composite material disclosed by the invention, the second phase is designed to be directionally arranged to form a shell-like bionic structure, so that the bionic composite material is endowed with good fracture toughness; a multistage auxiliary orientation method is adopted to ensure that the bionic composite material forms a shell-like bionic structure and has excellent strength and toughness, anisotropy of mechanical properties and functional characteristics is achieved, operation is easy, industrialization is easy, and the shell-like bionic composite material is suitable for the fields of aerospace, electronic equipment, buildings and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of the preparation of metal matrix composites, and particularly relates to a bionic composite material and a multi-stage assisted directional preparation method thereof. Background Art

[0002] The composite design of metal materials is a solution and development trend to achieve high performance and integrated structural functions of metal materials. Metal matrix composites usually have excellent mechanical properties such as high specific strength (stiffness), fatigue resistance, wear resistance, and high temperature resistance, as well as excellent functional properties such as good thermal and electrical conductivity and electromagnetic shielding performance. They are important lightweight materials and integrated structural-functional materials, and are widely used as key components in fields such as aerospace, nuclear power, weapons, transportation, and electronics. For example, the outer drill rod mechanism used in the sampling on the back of the moon by Chang'e-6 is made of silicon carbide particle-reinforced aluminum matrix composite. However, traditional metal matrix composites still have the scientific problem of the inversion of strength and toughness. Although adding second phases such as ceramics and graphene can improve the strength and hardness of the materials, the plasticity and toughness decrease due to stress concentration, and it is difficult to have both high strength and high toughness.

[0003] Although natural biological materials have simple components and mild forming conditions, they have excellent comprehensive mechanical properties due to their ingenious microstructural organizations. In natural shells, minerals and organic matters are alternately arranged in a layered form to form a "brick-mud" structure, endowing the shells with excellent comprehensive mechanical properties, and its fracture energy is three orders of magnitude higher than that of its components. Therefore, the microstructure design of biological materials provides inspiration for the structural design and performance optimization of high-performance metal matrix composites.

[0004] Chinese Patent (CN119433324A) discloses a multi-stage structured Al / Al2O3 composite material and a preparation method thereof. This invention prepares a multi-stage structured Al / Al2O3 composite material through 3D printing a calcium carbonate resin mold in combination with a freeze-casting technique, a metal melt pressure impregnation technique, and the optimized control of degreasing and calcium carbonate decomposition processes. However, on the one hand, the freeze-casting technique in this invention requires consumables such as liquid nitrogen, and on the other hand, the freezing time and vacuum drying time are relatively long, and the product size is restricted by factors such as the mold, thus having problems such as high cost, long cycle, complex operation, and difficulty in engineering.

[0005] Chinese Patent (CN119304189A) discloses a layered adjustable metal matrix composite material and a preparation method thereof. This invention alternately stacks ceramic-metal mixed layers and metal layers, and vacuum sintering under pressure to obtain a layered adjustable metal matrix composite material. However, the scales of the metal layer and the ceramic layer in this invention are relatively large (100μm - 1000μm), and it is difficult to fully exert the performance advantages of the layered structure composite material. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a bionic composite material in view of the deficiencies of the above-mentioned prior art. In this bionic composite material, a bionic structure similar to that of a shell is formed by designing the directional arrangement of the second phase, and mechanisms such as crack deflection and microcracks are introduced, endowing the bionic composite material with good fracture toughness, making it have both excellent strength and toughness, and solving the problem of the inversion of strength and toughness caused by the addition of the second phase in metal matrix composites.

[0007] To solve the above technical problems, the technical solution adopted by the present invention is: a bionic composite material, characterized in that it is composed of a metal matrix phase and a second phase with a microscopic preferred orientation, wherein the volume fraction of the second phase is 2% to 40%, and the second phase is directionally arranged to form a shell-like structure. More preferably, the volume fraction of the second phase is 2% to 30%.

[0008] The above-mentioned bionic composite material is characterized in that the metal matrix phase is selected from aluminum, magnesium, titanium, copper, silver, niobium, iron and their alloys, and the raw material powder of the second phase satisfies any of the following conditions: (a) when the raw material powder of the second phase is silicon carbide whiskers, glass fibers, carbon nanotubes or carbon fibers, the aspect ratio is 10 to 100, and the length is more than 10 times the particle size of the raw material powder of the metal matrix phase; (b) when the raw material powder of the second phase is alumina nanosheets, hexagonal boron nitride, graphene or MAX phase, the diameter-thickness ratio is 5 to 100, and the diameter is more than 10 times the particle size of the raw material powder of the metal matrix phase. By defining the size relationship between the raw material powder of the second phase including sheet-like and fibrous and the raw material powder of the metal matrix phase, the present invention is beneficial to the coating of the metal matrix phase on the surface of the second phase, is more likely to form a bionic structure, and realizes the densification of the bionic composite material.

[0009] At the same time, the present invention also discloses a multi-stage assisted directional preparation method of the above-mentioned bionic composite material, characterized in that the directional arrangement of the second phase to form a shell-like structure is realized through a multi-stage assisted directional method, and the multi-stage assisted directional method successively includes:

[0010] Step 1, primary powder orientation: making the raw material powder of the second phase preliminarily oriented by a physical method;

[0011] Step 2, secondary forming orientation: optimizing the directional structure of the second phase through pressing and sintering processes;

[0012] Step 3, tertiary deformation orientation: further strengthening the directional effect of the second phase through a plastic deformation process.

[0013] The multi-stage assisted directional preparation method of the above-mentioned bionic composite material is characterized in that any one of the following methods is adopted for the first-stage powder orientation in step one: (a) Mechanical orientation method: including vibration orientation or gravitational sedimentation orientation; (b) Liquid-phase separation orientation method: including vacuum filtration orientation or solvent evaporation orientation; (c) Field-assisted orientation method: including external magnetic field orientation or external electric field orientation.

[0014] The multi-stage assisted directional preparation method of the above-mentioned bionic composite material is characterized in that when the first-stage powder orientation is carried out by adopting (a) the mechanical orientation method in step one: the raw material powders of the metal matrix phase and the second phase are mixed and then ball-milled to obtain a uniformly mixed composite powder, and then an external force vibration method is adopted to make the raw material powders of the second phase in the composite powder be laid flat and oriented, or the composite powder is slowly gravitationally sedimented at a certain height to make the raw material powders of the second phase in the composite powder be oriented;

[0015] When the first-stage powder orientation is carried out by adopting (b) the liquid-phase separation orientation method: the raw material powders of the metal matrix phase, the second phase, the binder, the dispersant and the solvent are mixed and then ball-milled to obtain a uniformly mixed slurry, and then vacuum filtration or solvent evaporation method is adopted to separate the solid and liquid in the slurry, so as to realize the horizontal orientation arrangement of the raw material powders of the second phase;

[0016] When the first-stage powder orientation is carried out by adopting (c) the field-assisted orientation method: the surface of the raw material powder of the second phase is magnetized or the surface charge is regulated to carry stable charges, and then it is mixed with the raw material powder of the metal matrix phase to obtain a uniformly mixed composite powder, and then an external magnetic field or an external electric field is applied to make the magnetized or charged raw material powders of the second phase in the composite powder be oriented along the magnetic force direction or the electric force direction.

[0017] When the mechanical orientation method (a) is adopted in the present invention, an external force is applied to the composite powder for vibration. During the vibration process, the shear force drives the raw material powders of the second phase to rotate to a low energy state, so as to tend to be oriented parallel to the vibration direction, and it has no effect on the raw material powders of the metal matrix phase; or the composite powder is slowly gravitationally sedimented at a certain height. During the sedimentation process, forces such as gravity and air resistance and the rotational torque generated by gravity cause the raw material powders of the second phase in the composite powder to rotate and be oriented along the long axis direction thereof, and it has no effect on the raw material powders of the metal matrix phase. Generally, the mechanical orientation method is more suitable for the raw material powders of the second phase with a large aspect ratio.

[0018] When the liquid-phase separation orientation method (b) is adopted, during the solid-liquid separation process of vacuum filtration, the flaky raw material powders of the second phase are affected by the shear force and are oriented parallel to the surface of the filter membrane; during the solid-liquid separation process of solvent evaporation, the flaky raw material powders of the second phase are affected by the capillary force, and the maximum plane particles thereof tend to be horizontally arranged parallel to the deposition plane direction.

[0019] The multi-stage assisted orientation preparation method of the above-mentioned bionic composite material is characterized in that in the (a) mechanical orientation method, the height of gravitational sedimentation is 0.5 m to 1.5 m, an acrylic cylinder with a diameter of 20 cm to 50 cm is used as the container, the environment is indoors, and the wind speed does not exceed 0.2 m / s. By limiting the height of gravitational sedimentation, sufficient time is ensured for the raw material powder of the second phase to be oriented; by restricting the indoor environment and wind speed, the interference of forces other than gravity is reduced, and by limiting the size of the acrylic cylinder container, it is matched with the size of the mold commonly used in subsequent pressing.

[0020] The multi-stage assisted orientation preparation method of the above-mentioned bionic composite material is characterized in that in the (b) liquid phase separation orientation method, the binder used is one of hydroxypropyl methylcellulose, sucrose and guar gum, the dispersant is one of polyvinyl alcohol, Darvan C-N, polyacrylic acid and sodium dodecyl sulfonate, and the solvent is one of water, ethanol and methanol.

[0021] The multi-stage assisted orientation preparation method of the above-mentioned bionic composite material is characterized in that in step two, the secondary forming orientation is selected from any one of the following methods: (a) cold pressing to form a green body combined with hot pressing sintering orientation; (b) cold pressing to form a green body combined with spark plasma sintering orientation. The present invention utilizes the pressure and temperature effects of the cold pressing and sintering processes to soften the metal matrix phase, and the raw material powder of the second phase is adjusted along the low-resistance direction, that is, the primary powder orientation direction, under the action of plastic flow or liquid phase-assisted rearrangement, further optimizing the orientation of the raw material powder of the second phase in the green body.

[0022] The multi-stage assisted orientation preparation method of the above-mentioned bionic composite material is characterized in that the cold pressing direction in the secondary forming orientation is the direction perpendicular to the composite powder orientation plane obtained after the primary powder is oriented, the pressure is 10 MPa to 500 MPa, the pressure direction in hot pressing sintering or spark plasma sintering is the direction perpendicular to the composite powder orientation plane obtained after the primary powder is oriented, and the pressure is 10 MPa to 200 MPa, and the temperature is 0.6T m ~0.9T m ,T m is the melting point of the raw material powder of the metal matrix phase;

[0023] For the composite powder obtained after the primary powder is oriented by using the (b) liquid phase separation orientation method, before hot pressing sintering or spark plasma sintering, the green body obtained after cold pressing is subjected to high-temperature heat treatment at 300 °C to 500 °C to remove the dispersant and binder in the green body.

[0024] In the present invention, the oriented plane of the composite powder obtained after the first-stage powder orientation refers to the plane on which the raw material powders of the second phase (including flakes and fibers) are preferentially arranged after the first-stage powder orientation. Among them, for the flaky raw material powders of the second phase, after the first-stage orientation, their largest plane, i.e., the lamellar surface, is parallel to the horizontal plane, and at this time, the horizontal plane is the oriented plane. For the fibrous raw material powders of the second phase, after the first-stage orientation, their long axes are parallel to a certain direction (such as the horizontal plane), and then the plane where their long axes are located is the oriented plane.

[0025] The above multi-stage assisted orientation preparation method of the bionic composite material is characterized in that in step three, the three-stage deformation orientation is selected from any one of the following methods: (a) extrusion orientation; (b) rolling orientation. Usually, hot extrusion or hot rolling is adopted. At high temperatures, the metal matrix softens, and large plastic deformation occurs under the action of extrusion force or rolling force, while the raw material powders of the second phase extend along the extrusion direction or rolling direction, thereby realizing three-stage deformation orientation. Among them, during the extrusion orientation process, the extrusion shear force causes the flaky raw material powders of the second phase to rotate to their largest plane, parallel to the extrusion direction, that is, their long axes are arranged along the extrusion direction, and the greater the extrusion deformation amount, the more consistent the orientation. And the long axes of the fibrous raw material powders of the second phase tend to be parallel to the extrusion direction, forming axial orientation. During the rolling orientation process, after the metal matrix softens, it flows along the rolling plane, and the raw material powders of the second phase are adjusted in orientation under the action of shear force. The flaky raw material powders of the second phase tend to rotate to the largest plane and be parallel to the rolling plane, forming a layered structure, and multi-pass rolling is beneficial to gradually optimize the orientation effect. The long axes of the fibrous raw material powders of the second phase tend to be parallel to the rolling direction.

[0026] The above multi-stage assisted orientation preparation method of the bionic composite material is characterized in that the temperature adopted for the extrusion orientation is 0.4T m ~0.8T m , the extrusion ratio is 5 - 20, the extrusion direction is perpendicular to the sintering pressure direction in step two, and the temperature adopted for the rolling orientation is 0.4T m ~0.8T m , the deformation amount is 1% - 10%, the rolling direction is perpendicular to the sintering pressure direction in step two, and T m is the melting point of the raw material powders of the metal matrix phase. The present invention controls the temperature of the extrusion orientation and the rolling orientation to ensure that the metal matrix is softened to an appropriate degree, avoiding the reduction of the metal matrix viscosity due to too high temperature, resulting in the inability of the shear force to effectively drive the second-phase orientation, and at the same time avoiding the difficulty of achieving plastic deformation due to too low temperature. By controlling the extrusion ratio and the deformation amount, the strengthening orientation effect is ensured, avoiding damage to the orientation structure due to too large deformation amount and the inability to achieve the effect of optimizing the orientation due to too small deformation amount.

[0027] The present invention has the following advantages compared with the prior art:

[0028] 1. In the bionic composite material of the present invention, a bionic structure similar to that of a shell is formed by designing the directional arrangement of the second phase. By utilizing this bionic structure similar to that of a shell to introduce mechanisms such as crack deflection and microcracks, the bionic composite material is endowed with good fracture toughness, making it have both excellent strength and toughness, and being suitable as high-performance structural components, power system switches, components of electronic devices, building sound insulation boards, etc.

[0029] 2. The present invention adopts a multi-stage assisted orientation method to prepare the bionic composite material. Firstly, the primary powder orientation is achieved through the first-stage powder orientation to preliminarily orient the raw material powder of the second phase. The second-phase orientation structure is optimized through the second-stage forming orientation, and the second-phase orientation effect is strengthened through the third-stage deformation orientation, thereby ensuring that the second phase in the bionic composite material is directionally arranged to form a bionic structure similar to that of a shell, and realizing the simultaneous improvement of the strength and toughness of the bionic composite material.

[0030] 3. The present invention realizes the anisotropy of the mechanical properties and functional characteristics of the bionic composite material through the multi-stage assisted orientation method: in the direction parallel to the orientation direction, the bionic composite material has good hardness, strength, stiffness, thermal conductivity, electrical conductivity, and damping properties; in the direction perpendicular to the orientation direction, the bionic composite material has good plasticity, toughness, and electromagnetic shielding effect, which is beneficial to meeting different usage requirements.

[0031] 4. The present invention can effectively regulate the microstructure and mechanical properties of the bionic composite material by regulating the composition, content of the bionic composite material, and the process parameters of the multi-stage assisted orientation method, thereby expanding the scope of application of the bionic composite material.

[0032] 5. The multi-stage assisted orientation method of the present invention is simple in operation, low in cost, short in cycle, low in equipment requirements, wide in application range, the prepared bionic composite material has no size limitation, is easy to be mass-produced, and the bionic composite material has excellent comprehensive performance and can be widely applied to high-performance structural components in the fields of aerospace, electronic devices, architecture, etc.

[0033] The technical solutions of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Description of the Drawings

[0034] Figure 1 It is a schematic preparation route diagram of the bionic composite material prepared by the multi-stage assisted orientation method of the present invention.

[0035] Figure 2 It is a process schematic diagram of preparing a silicon carbide / aluminum alloy bionic composite material by the multi-stage assisted orientation method combining gravity sedimentation orientation, hot press sintering orientation, and rolling orientation in Example 1 of the present invention.

[0036] Figure 3 It is a schematic diagram of the crack propagation path of the silicon carbide / aluminum alloy bionic composite material prepared in Example 1 of the present invention.

[0037] Figure 4 It is a process schematic diagram of preparing graphene / copper alloy bionic composite material by a multi-stage assisted orientation method combining vacuum filtration orientation, spark plasma sintering orientation and extrusion orientation in Embodiment 2 of the present invention.

[0038] Figure 5 It is a scanning electron micrograph of preparing graphene / silver bionic composite material by a multi-stage assisted orientation method combining vacuum filtration orientation, spark plasma sintering orientation and extrusion orientation in Embodiment 3 of the present invention. Detailed implementation manners

[0039] As Figure 1 shown, the process of preparing the bionic composite material by the multi-stage assisted orientation method of the present invention is as follows: First, the raw material powder of the metal matrix phase (metal powder in the figure) and the raw material powder of the second phase (second phase powder in the figure) are processed and then ball-milled and mixed evenly to form a composite powder or slurry. Then, vibration orientation, gravity sedimentation orientation, vacuum filtration orientation, evaporation solvent orientation, external magnetic field orientation or external electric field orientation are used in sequence to achieve primary powder orientation. Cold pressing is used to form a green body combined with hot pressing sintering orientation or cold pressing is used to form a green body combined with spark plasma sintering orientation to achieve secondary forming orientation. Extrusion orientation or rolling orientation is used to achieve tertiary deformation orientation, and the bionic composite material is obtained.

[0040] Embodiment 1

[0041] The silicon carbide / aluminum alloy bionic composite material of this embodiment is composed of an aluminum alloy matrix phase and a silicon carbide second phase with microscopic preferred orientation. Among them, the volume fraction of the silicon carbide second phase is 3%, and the silicon carbide second phase is arranged in an oriented manner to form a shell-like structure.

[0042] As Figure 2 shown, the specific process of preparing the silicon carbide / aluminum alloy bionic composite material by the multi-stage assisted orientation method combining gravity sedimentation orientation, hot pressing sintering orientation and rolling orientation in this embodiment includes:

[0043] Step 1. Primary powder orientation:

[0044] Step 101. Dispersion of silicon carbide whiskers: The silicon carbide whiskers are added to absolute ethanol and ultrasonically dispersed for 2h, and then placed in a vacuum drying oven and dried for more than 24h to obtain uniformly dispersed silicon carbide whiskers; the length of the silicon carbide whiskers is 10μm - 20μm, the diameter is 300nm - 600nm, and the aspect ratio is about 3

[0045] Step 102: Preparation of composite powder: The silicon carbide whiskers dispersed evenly in Step 101 and aluminum alloy powder with an average particle size of 500 nm and grade AA 6061 were added into a plastic wide-mouth bottle at a mass ratio of 1:28, and 8 alumina grinding balls with a diameter of 5 mm were added. After sealing the wide-mouth bottle with the bottle cap, it was placed on a drum ball mill for ball milling and dispersion. The ball milling speed was 100 rpm, and the ball milling time was 48 h to obtain the composite powder;

[0046] Step 103: Gravity sedimentation orientation: The composite powder in Step 102 was slowly and freely gravitationally sedimented from a height of 1.2 m. During the gravity sedimentation process, the outside of the composite powder was protected by an acrylic cylinder with a diameter of 30 cm and a height of 1.2 m as the container. The environment was indoors, the wind speed was 0.2 m / s, and a cold pressing mold was placed at the bottom to collect the powder sedimented by gravity. The gravity sedimentation process was repeated until all the powder was collected in the cold pressing mold. At this time, the silicon carbide whiskers were evenly distributed in the cold pressing mold and were oriented and arranged along their long axes;

[0047] Step Two: Secondary forming orientation: The powder in the cold pressing mold in Step 103 was pressed using a press along the plane perpendicular to the orientation of the silicon carbide whiskers in the powder. The pressure was 200 MPa, the pressure holding time was 1 h, and the temperature was room temperature. Then, the preliminarily formed green body after pressing was placed into a hot pressing mold (the inner cavity size was the same as that of the cold pressing mold) for hot pressing sintering. The pressure direction of the hot pressing sintering was the same as that of the cold pressing, perpendicular to the plane of the silicon carbide whisker orientation. The pressure was 50 MPa, the temperature was 520 °C, the atmosphere was vacuum, the pressure holding time was 1 h, and the heating and cooling rates were 5 °C / min. After cooling, it was taken out from the hot pressing mold to obtain the sintered body;

[0048] Step Three: Tertiary deformation orientation: The sintered body obtained in Step Two was machined to the dimensions required for extrusion, and then preheated for hot extrusion deformation. The hot extrusion temperature was 400 °C, the extrusion ratio was 5, and the hot extrusion direction was perpendicular to the pressure direction of the hot pressing sintering in Step Two to obtain the silicon carbide / aluminum alloy bionic composite material.

[0049] Figure 3 is a schematic diagram of the crack propagation path of the silicon carbide / aluminum alloy bionic composite material prepared in this embodiment. From Figure 3 it can be seen that when the crack encounters the silicon carbide phase arranged in an oriented manner during the propagation process, it will deflect significantly, forming a "stepped" crack path, avoiding a straight-line catastrophic fracture, indicating that the silicon carbide / aluminum alloy bionic composite material has a stable crack propagation ability, demonstrating that the bionic composite material of the present invention has good fracture toughness.

[0050] In this embodiment, the silicon carbide second phase in the silicon carbide / aluminum alloy bionic composite material can also be replaced by glass fiber or carbon fiber. The aspect ratio of the raw material powder of the corresponding second phase, namely glass fiber or carbon fiber, is 10 to 100, and the length is more than 10 times the particle size of the raw material powder of the metal matrix phase.

[0051] Example 2

[0052] The graphene / copper alloy bionic composite material of this embodiment is composed of a copper alloy phase and a graphene second phase with microscopic preferred orientation. Among them, the volume fraction of the graphene second phase is 2%, and the graphene second phase is arranged directionally to form a shell-like structure.

[0053] As Figure 4 shown, the specific process of preparing the graphene / aluminum bionic composite material by using a multi-stage assisted orientation method combining vacuum filtration orientation, spark plasma sintering orientation, and rolling orientation includes:

[0054] Step 1. Primary powder orientation:

[0055] Step 101. Dispersion of graphene: Add graphene to deionized water and perform ultrasonic dispersion for 1 h with an ultrasonic power of 500 W, and then place it in a vacuum drying oven to dry for more than 24 h to obtain uniformly dispersed graphene; the diameter of the graphene is 1 μm to 3 μm, the thickness is 300 nm to 500 nm, and the aspect ratio is about 5.

[0056] Step 102. Preparation of water-based slurry: Mix sodium dodecyl sulfate and deionized water in a mass ratio of 1:199 and add them to a wide-mouth bottle, and continuously stir until completely dissolved to obtain an aqueous solution. Then, disperse the uniformly dispersed graphene in step 101 and copper alloy powder with an average particle size of 100 nm and a grade of CuZn20 in the aqueous solution in a mass ratio of 1:188, and add hydroxypropyl methyl cellulose according to 2% of the mass content of the dispersed solution. Perform magnetic stirring for 30 min under ultrasonic assistance, and then add 8 alumina grinding balls with a diameter of 5 mm for ball milling dispersion. The ball milling speed is 50 rpm, and the ball milling time is 24 h to obtain a water-based slurry.

[0057] Step 103. Vacuum filtration orientation: Slowly pour the water-based slurry in step 102 into a funnel, and perform vacuum filtration under a vacuum negative pressure condition, so that the water in the water-based slurry is continuously filtered through the nylon membrane and removed, while the graphene and copper alloy powder are deposited in the funnel. At the same time, under the negative pressure condition, the flaky graphene powder tends to be laid flat and oriented. Repeat the vacuum filtration process until all the water is removed, and all the graphene and copper alloy powder are deposited in the funnel to form a deposit. Take out the deposit and place it in a vacuum drying oven to dry at 50 °C for more than 24 h to obtain a dry deposit.

[0058] Step 2. Secondary forming orientation: Cut the dried deposit in Step 103 according to the size of the cold pressing die, and then use a press to press along the direction perpendicular to the graphene orientation plane in the cut dried deposit in the cold pressing die. The pressure is 200 MPa, the pressure holding time is 1 h, the temperature is room temperature. Place the preliminarily formed blank after pressing into a tubular furnace for high-temperature heat treatment to remove the dispersant and binder in the blank. The temperature is 500 °C, the atmosphere is argon, the time is 1 h, and the heating rate is 5 °C / min. Then place it into a die (the inner cavity size is the same as that of the cold pressing die) for spark plasma sintering. The temperature is 750 °C, the atmosphere is vacuum, the heat preservation time is 5 min, the pressure is 50 MPa, the heating rate is 200 °C / min, the cooling rate is 5 °C / min, and the pressure direction of the spark plasma sintering is perpendicular to the graphene orientation plane. Take it out of the die after cooling to obtain a sintered body;

[0059] Step 3. Tertiary deformation orientation: Machine the sintered body obtained in Step 2 to the dimensions required for rolling, and then preheat for hot rolling deformation. The hot rolling temperature is 600 °C, the deformation amount is 3%, and the hot rolling direction is perpendicular to the pressure direction of the spark plasma sintering in Step 2 to obtain a graphene / copper alloy bionic composite material.

[0060] In this embodiment, the sodium dodecyl sulfate used for preparing the aqueous slurry can also be replaced by polyvinyl alcohol, Darvan C-N or polyacrylic acid, the solvent deionized water can also be replaced by ethanol or methanol, and the binder hydroxypropyl methylcellulose can also be sucrose or guar gum.

[0061] Example 3

[0062] The difference between this embodiment and Example 2 is that the copper alloy phase in the graphene / copper alloy bionic composite material is replaced by a silver phase, that is, a graphene / silver bionic composite material; in Step 102, the uniformly dispersed graphene and silver powder with an average particle size of 50 nm are dispersed in an aqueous solution according to a mass ratio of 1:200; the temperature of the spark plasma sintering in Step 2 is 800 °C; the hot rolling temperature in Step 3 is 650 °C.

[0063] The scanning electron micrograph of the graphene / silver bionic composite material prepared in this embodiment is as Figure 5 shown, where the left figure is a low-magnification figure and the right figure is a high-magnification figure. It can be seen from Figure 5 this that the graphene in the graphene / silver bionic composite material is oriented to form a shell-like structure.

[0064] Example 4

[0065] The alumina / magnesium alloy bionic composite material of this embodiment is composed of a magnesium alloy matrix phase and a second alumina phase with microscopic preferred orientation. Among them, the volume fraction of the second alumina phase is 30%, and the second alumina phase is arranged directionally to form a shell-like structure.

[0066] The specific process of preparing the silicon carbide / aluminum alloy bionic composite material by using a multi-stage assisted orientation method combining external magnetic field orientation, hot pressing sintering orientation and rolling orientation in this embodiment includes:

[0067] Step 1: Primary powder orientation:

[0068] Step 101: Dispersion of alumina nanosheets: Add alumina nanosheets to absolute ethanol and perform ultrasonic dispersion for 2h, then place them in a vacuum drying oven and dry for more than 24h to obtain uniformly dispersed alumina nanosheets; the diameter of the alumina nanosheets is 5μm - 10μm, the thickness is 200nm - 500nm, and the aspect ratio is about 20.

[0069] Step 102: Surface treatment of alumina nanosheets: Add the uniformly dispersed alumina nanosheets in Step 101 to a solution containing 20g / L of SnCl2·2H2O, 20mL / L of HCl, and 0.2g / L of Sn for sensitization. After sufficient reaction and cleaning, alumina nanosheets with a Sn 2+ layer are obtained. Then add them to a solution containing 0.3g / L of PdCl2 and 10mL / L of HCl for activation. After sufficient reaction and cleaning, activated alumina nanosheets with a Pd layer on the surface are obtained. Then add them to a electroless plating solution containing 25g / L of NiSO4·6H2O, 25g / L of NaH2PO4·H2O, and 15g / L of CH3COOH for surface nickel plating. The temperature is 80°C, the pH is 7 - 8, and the nickel plating time is not less than 30min. After completion, wash the precipitate to obtain alumina nanosheets with nickel plating on the surface;

[0070] Step 103: External magnetic field orientation: Mix the nickel-plated alumina nanosheets on the surface in Step 102 with magnesium alloy powder of grade AZ91D and an average particle size of 500nm according to a mass ratio of 1:1.05 and add them to a thin-walled graphite mold. Then place it under the condition of an external magnetic field to induce the directional arrangement of alumina nanosheets. The magnetic field strength is 5T to obtain a composite powder with directional arrangement;

[0071] Step 2. Secondary forming orientation: Use a press to press the composite powder arranged directionally in Step 103 placed in the cold pressing die along the direction perpendicular to the orientation plane of the alumina nanosheets in the composite powder, with a pressure of 100 MPa, a holding time of 1 h, and a temperature of room temperature. Then, place the preliminarily formed green body after pressing into a hot pressing die (the inner cavity size is the same as that of the cold pressing die) for hot pressing sintering. The pressure direction of the hot pressing sintering is the same as that of the pressing, perpendicular to the orientation plane of the alumina nanosheets, with a pressure of 30 MPa, a temperature of 480 °C, a vacuum atmosphere, a holding time of 1 h, a heating and cooling rate of 5 °C / min. After cooling, take it out from the hot pressing die to obtain a sintered body;

[0072] Step 3. Tertiary deformation orientation: Machine the sintered body obtained in Step 2 to the dimensions required for rolling, then preheat and perform hot rolling deformation. The hot rolling temperature is 400 °C, the deformation amount is 3%, and the rolling direction is perpendicular to the pressure direction of the hot pressing sintering in Step 2 to obtain an alumina / magnesium alloy bio-inspired composite material.

[0073] In this embodiment, the alumina second phase in the alumina / magnesium alloy bio-inspired composite material can also be replaced by the MAX phase. The aspect ratio of the corresponding second-phase raw material powder, i.e., the MAX-phase raw material powder, is 5 - 100, and the diameter is more than 10 times the particle diameter of the metal matrix phase raw material powder.

[0074] Example 5

[0075] The carbon nanotube / titanium alloy bio-inspired composite material of this embodiment is composed of a titanium alloy matrix phase and a carbon nanotube second phase with microscopic preferred orientation. Among them, the volume fraction of the carbon nanotube second phase is 10%, and the carbon nanotube second phase is arranged directionally to form a shell-like structure.

[0076] The specific process of preparing the carbon nanotube / titanium alloy bio-inspired composite material by using a multi-stage assisted orientation method combining evaporation solvent orientation, spark plasma sintering orientation, and rolling orientation in this embodiment includes:

[0077] Step 1. Primary powder orientation:

[0078] Step 101. Dispersion of carbon nanotubes: Add carbon nanotubes to deionized water and perform ultrasonic dispersion for 1 h with a ultrasonic power of 500 W, then place it in a vacuum drying oven and dry it for more than 24 h to obtain uniformly dispersed carbon nanotubes; the length of the carbon nanotubes is 5 μm - 10 μm, the diameter is 100 nm - 300 nm, and the aspect ratio is 30.

[0079] Step 102: Preparation of the aqueous slurry: Sodium dodecyl sulfonate and deionized water are mixed in a mass ratio of 1:199 and added to a wide-mouth bottle. Stir continuously until completely dissolved to obtain an aqueous solution. Then, the carbon nanotubes dispersed uniformly in Step 101 and titanium alloy powder with the brand TC4 and an average particle size of 500 nm are dispersed in the aqueous solution in a mass ratio of 1:25. Hydroxypropyl methylcellulose is added at 3% of the mass content of the dispersed solution. Magnetic stirring is carried out for 30 min under ultrasonic assistance. Then, 8 alumina grinding balls with a diameter of 5 mm are added for ball milling dispersion. The ball milling speed is 50 rpm, and the ball milling time is 24 h to obtain the aqueous slurry;

[0080] Step 103: Evaporation solvent orientation: Slowly pour the aqueous slurry in Step 102 into a petri dish, and then carry out water bath heating at a temperature of 45 °C for no less than 24 h until all the water evaporates to obtain a composite powder. At this time, the carbon nanotubes are laid flat and oriented along their long axis direction;

[0081] Step Two: Secondary forming orientation: Use a press to press along the direction perpendicular to the plane where the carbon nanotubes are oriented in the composite powder in Step 103 placed in the cold pressing mold. The pressure is 100 MPa, the pressure holding time is 1 h, and the temperature is room temperature. The preliminarily formed blank after pressing is placed in a tube furnace for high-temperature heat treatment to remove the dispersant and binder in the blank. The temperature is 500 °C, the atmosphere is argon, and the time is 1 h. The heating rate is 5 °C / min. Then, it is placed in a mold (the inner cavity size is the same as that of the cold pressing mold) for spark plasma sintering. The temperature is 1200 °C, the atmosphere is vacuum, the holding time is 5 min, the pressure is 20 MPa, the heating rate is 200 °C / min, and the cooling rate is 5 °C / min. And the pressure direction of the spark plasma sintering is perpendicular to the carbon nanotube orientation plane. After cooling, it is taken out of the mold to obtain a sintered body;

[0082] Step Three: Tertiary deformation orientation: The sintered body obtained in Step Two is machined to the dimensions required for rolling, and then preheated for hot rolling deformation. The hot rolling temperature is 900 °C, the deformation amount is 3%, and the hot rolling direction is perpendicular to the pressure direction of the spark plasma sintering in Step Two to obtain the carbon nanotube / titanium alloy bionic composite material.

[0083] Example 6

[0084] The difference between this example and Example 5 is that the titanium alloy phase in the carbon nanotube / titanium alloy bionic composite material is replaced by a niobium alloy phase, that is, a carbon nanotube / niobium alloy bionic composite material; in Step 102, the uniformly dispersed carbon nanotubes and niobium alloy powder with the brand Nb521 are dispersed in the aqueous solution in a mass ratio of 1:45; the temperature of the spark plasma sintering in Step Two is 1800 °C; the hot rolling temperature in Step Three is 1300 °C.

[0085] Example 7

[0086] The hexagonal boron nitride / steel bionic composite material of this example is composed of a steel matrix phase and a second hexagonal boron nitride phase with microscopic preferred orientation. Among them, the volume fraction of the second hexagonal boron nitride phase is 40%, and the second hexagonal boron nitride phase is arranged directionally to form a shell-like structure.

[0087] The specific process of preparing the hexagonal boron nitride / steel bionic composite material by using a multi-stage assisted orientation method combining oscillating orientation, hot pressing sintering orientation and extrusion orientation in this example includes:

[0088] Step 1: Primary powder orientation:

[0089] Step 101: Dispersion of hexagonal boron nitride: Add hexagonal boron nitride to absolute ethanol and perform ultrasonic dispersion for 2h, then place it in a vacuum drying oven and dry it for more than 24h to obtain uniformly dispersed hexagonal boron nitride; the diameter of the hexagonal boron nitride is 1μm - 5μm, the thickness is 100nm - 500nm, and the aspect ratio is 10.

[0090] Step 102: Preparation of composite powder: Add the uniformly dispersed hexagonal boron nitride in Step 101 and steel powder with a grade of 18Ni and an average particle size of 100nm to a plastic wide-mouth bottle according to a mass ratio of 1:5.2, and add 8 alumina grinding balls with a diameter of 5mm. After covering the wide-mouth bottle with the bottle cap and sealing it, place it on a drum ball mill for ball milling and dispersion. The ball milling speed is 100rpm, and the ball milling time is 48h to obtain composite powder.

[0091] Step 103: Oscillating orientation: Pour the composite powder in Step 102 into a cold pressing mold, and then place the cold pressing mold on an electric vibration platform for oscillating orientation. The vibration frequency is 50Hz, and the time is 2h. After oscillation, the plane of the hexagonal boron nitride in the composite powder is parallel to the plane of the oscillating force, realizing preliminary orientation.

[0092] Step 2: Secondary forming orientation: Use a press to press along the direction perpendicular to the orientation plane of the hexagonal boron nitride in the composite powder after oscillating orientation in the cold pressing mold in Step 103. The pressure is 100MPa, the pressure holding time is 1h, and the temperature is room temperature. Then place the preliminarily formed blank after pressing into a hot pressing mold (the inner cavity size is the same as that of the cold pressing mold) for hot pressing sintering. The pressure direction of the hot pressing sintering is the same as that of the pressing, perpendicular to the orientation plane of the hexagonal boron nitride. The pressure is 20MPa, the temperature is 1100℃, the atmosphere is vacuum, the pressure holding time is 1h, and the heating and cooling rates are 5℃ / min. After cooling, take it out from the hot pressing mold to obtain a sintered body.

[0093] Step 3: Tertiary deformation orientation: The sintered body obtained in Step 2 is machined to the required size for extrusion, and then preheated for hot extrusion deformation. The hot extrusion temperature is 1000°C, the extrusion ratio is 8, and the extrusion direction is perpendicular to the pressure direction of hot pressing and sintering in Step 2, obtaining a hexagonal boron nitride / steel bionic composite material.

[0094] The above are only the preferred embodiments of the present invention, and do not impose any limitations on the present invention. Any simple modifications, changes, and equivalent variations made to the above embodiments according to the technical essence of the invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A bionic composite material, characterized in that, It is composed of a metal matrix phase and a second phase with a microscopic preferred orientation. Among them, the volume fraction of the second phase is 2% - 40%, and the second phase is arranged directionally to form a shell-like structure.

2. The bionic composite material according to claim 1, wherein, The metal matrix phase is selected from aluminum, magnesium, titanium, copper, silver, niobium, iron and their alloys. The raw material powder of the second phase satisfies any of the following conditions: (a) When the raw material powder of the second phase is silicon carbide whiskers, glass fibers, carbon nanotubes or carbon fibers, the aspect ratio is 10 - 100, and the length is more than 10 times the particle size of the raw material powder of the metal matrix phase; (b) When the raw material powder of the second phase is alumina nanosheets, hexagonal boron nitride, graphene or MAX phase, the diameter-thickness ratio is 5 - 100, and the diameter is more than 10 times the particle size of the raw material powder of the metal matrix phase.

3. A multi-level assisted directional preparation method of the bionic composite material as described in claim 1 or 2, characterized in that, The directional arrangement of the second phase to form a shell-like structure is achieved by a multi-stage assisted orientation method. This multi-stage assisted orientation method includes successively: Step 1, primary powder orientation: The raw material powder of the second phase is preliminarily oriented by a physical method. Step 2, secondary forming orientation: The directional structure of the second phase is optimized by pressing and sintering processes. Step 3, tertiary deformation orientation: The directional effect of the second phase is further strengthened by a plastic deformation process.

4. The multi-stage assisted directional preparation method of the bionic composite material according to claim 3, characterized in that, Any of the following methods is adopted for the primary powder orientation in Step 1: (a) Mechanical orientation method: including vibration orientation or gravitational sedimentation orientation; (b) Liquid phase separation orientation method: including vacuum filtration orientation or solvent evaporation orientation; (c) Field-assisted orientation method: including external magnetic field orientation or external electric field orientation.

5. The multi-level assisted directional preparation method of the bionic composite material according to claim 4, characterized in that The process of primary powder orientation by adopting (a) the mechanical orientation method in Step 1 is: Mix the raw material powder of the metal matrix phase and the raw material powder of the second phase and then carry out ball milling to obtain a uniformly mixed composite powder. Then, use an external force vibration method to make the raw material powder of the second phase in the composite powder lay flat and be oriented, or slowly sediment the composite powder at a certain height under gravity to make the raw material powder of the second phase in the composite powder be oriented. The process of primary powder orientation by adopting (b) the liquid phase separation orientation method is: Mix the raw material powder of the metal matrix phase, the raw material powder of the second phase with an adhesive, a dispersant and a solvent and then carry out ball milling to obtain a uniformly mixed slurry. Then, use the vacuum filtration or solvent evaporation method to separate the solid and liquid in the slurry, and realize the directional arrangement of the raw material powder of the second phase along the horizontal direction. The process of primary powder orientation by adopting (c) the field-assisted orientation method is: Carry out surface magnetization or surface charge regulation on the raw material powder of the second phase to carry stable charges, and then mix it with the raw material powder of the metal matrix phase to obtain a uniformly mixed composite powder. Then, apply an external magnetic field or an external electric field to make the magnetized or charged raw material powder of the second phase in the composite powder be oriented along the magnetic force direction or the electric force direction.

6. The multi-stage assisted directional preparation method of the bionic composite material according to claim 5, wherein, In the (a) mechanical orientation method, the height of gravitational sedimentation is 0.5m - 1.5m, an acrylic cylinder with a diameter of 20cm - 50cm is used as the container, the environment is indoor, and the wind speed does not exceed 0.2m / s.

7. The multi-stage assisted directional preparation method of the bionic composite material according to claim 5, wherein, In the said (b) liquid-phase separation orientation method, the binder used is one of hydroxypropyl methylcellulose, sucrose and guar gum, the dispersant is one of polyvinyl alcohol, Darvan C-N, polyacrylic acid and sodium dodecyl sulfonate, and the solvent is one of water, ethanol and methanol.

8. The multi-stage assisted directional preparation method of the bionic composite material according to claim 3, wherein, The secondary forming orientation described in step two is selected from any one of the following methods: (a) cold pressing to form a green body combined with hot pressing sintering orientation; (b) cold pressing to form a green body combined with spark plasma sintering orientation.

9. The multi-stage assisted directional preparation method of the bionic composite material according to claim 8, characterized in that, The cold pressing direction in the secondary forming orientation is perpendicular to the composite powder orientation plane obtained after the primary powder orientation, with a pressure of 10 MPa to 500 MPa. The pressure direction in hot press sintering or spark plasma sintering is perpendicular to the composite powder orientation plane obtained after the primary powder orientation, and the pressure is 10 MPa to 200 MPa, and the temperature is 0.6T m ~0.9T m , T m is the melting point of the raw material powder of the metal matrix phase; For the composite powder obtained after the primary powder orientation by using the (b) liquid-phase separation orientation method, before hot pressing sintering or spark plasma sintering, the green body obtained after cold pressing is subjected to high-temperature heat treatment at 300°C to 500°C to remove the dispersant and binder in the green body.

10. The multi-stage assisted directional preparation method of the bionic composite material according to claim 3, characterized in that, The tertiary deformation orientation described in step three is selected from any one of the following methods: (a) extrusion orientation; (b) rolling orientation.

11. The multi-level assisted directional preparation method of the bionic composite material according to claim 10, wherein, The temperature used for extrusion orientation is 0.4T m to 0.8T m , the extrusion ratio is 5 to 20, the extrusion direction is perpendicular to the pressure direction of sintering in step two, and the temperature used for rolling orientation is 0.4T m to 0.8T m , the deformation amount is 1% to 10%, the rolling direction is perpendicular to the pressure direction of sintering in step two, and T m is the melting point of the raw material powder of the metal matrix phase.

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