A method for preparing a titanium-based composite material with graphene-titanium double-connection structure

Abstract

The application relates to a preparation method of a titanium-based composite material with a graphene-Ti double-connected structure. The application aims at solving the problems of high cost of the composite material, low utilization rate of the second phase and poor thermal-conducting-mechanical performance caused by the need to add a large amount of expensive high-thermal-conducting second phase such as graphene and diamond in the preparation of a high-thermal-conducting titanium-based composite material in the prior art. The method is as follows: based on the idea of composite material configuration design and regulation, graphene nanosheets are electrophoretically deposited on a designed titanium-based frame, then titanium-based powder material is used to fill the frame, and the preparation of the double-connected graphene / Ti-based composite material is realized through spark plasma sintering. The application is used for aircraft surface hot end components.

Description

TECHNICAL FIELD

[0001] The application relates to a preparation method of a titanium-based composite material with a graphene-Ti double-connected structure. BACKGROUND

[0002] With the rapid development of China's aerospace industry, the performance of aircraft is continuously upgraded, and the requirements for the materials of the hot end components on the surface of the aircraft are becoming increasingly stringent. Lightweight, heat-resistant and high-strength characteristics have become a necessity. Discontinuous reinforced titanium matrix composites (DRTMCs) have emerged as the hottest topic, and have stood firm in the field of aerospace structural materials due to their advantages of lightweight, high specific strength and excellent creep resistance. In recent years, researchers have discovered a new path: adding nano-TiB whiskers with superlative strengthening efficiency to DRTMCs. These whiskers, like "traffic controllers" in the microscopic world, can effectively block dislocation movement and control grain boundary sliding at high temperatures, injecting a "strong heart needle" into the room temperature and high temperature strength of the composite material, and greatly expanding the application field of titanium matrix composites.

[0003] However, a bottleneck problem in the application of titanium matrix composites is that when the titanium matrix composite is used as an aerospace surface hot end component, it will generate a large amount of aerodynamic heat due to the severe friction with the air. Since the thermal conductivity of the titanium matrix composite itself is low (about 6.5 W / (m·K)), the heat in the titanium matrix composite cannot be quickly dissipated, causing the local temperature of the titanium alloy to be too high and resulting in softening failure. To overcome the above problems, the current titanium matrix composite mainly uses thermal conductive coating and thermal barrier coating to relieve the heat accumulation on the surface of the composite material. However, the bonding force between the coating and the matrix is weak and easy to fall off, and for components with complex shapes, it is difficult for the coating to achieve complete and uniform coating. Therefore, research based on improving the thermal conductivity of titanium matrix composites has important engineering significance. To improve the transmission efficiency of phonons in the material, the grain in the material should be coarse and the distortion should be small; while small grains and large lattice distortions are beneficial to the strength of the composite material, which leads to the phenomenon of intrinsic inversion of thermal conductivity and strength. Therefore, it is also of great scientific significance to achieve the coordinated improvement of the thermal conductivity and strength of titanium matrix composites through organizational structure design.

[0004] Graphene, as a new type of two-dimensional carbon material, is widely used to improve the mechanical properties and thermal conductivity of metal matrix composites due to its extremely high strength (about 130 GPa) and thermal conductivity (about 5300 W / (m·K)). However, in DRTMCs, due to the low thermal conductivity of the titanium alloy matrix itself and the large interfacial thermal resistance between graphene and the matrix, in order to significantly improve the thermal conductivity of the composite material, a large amount of graphene needs to be added to construct a continuous high-thermal-conductivity channel, which will destroy the connectivity of the matrix and is not conducive to the mechanical properties of the composite material. This has caused a bottleneck problem that the performance of graphene-reinforced DRTMCs is difficult to further improve.

[0005] In summary, in the prior art, in order to stack the thermal conductivity, a large amount of high-thermal-conductivity second phase such as graphene and diamond is often added, resulting in high cost of the composite material, low utilization rate of the second phase, and poor thermal-mechanical properties. Therefore, there is an urgent need for a new type of high-thermal-conductivity high-strength titanium-based composite material that can reduce the cost of the material while further improving the thermal and mechanical properties of the composite material. SUMMARY

[0006] The present application is to solve the problem of the prior art in preparing a high-thermal-conductivity titanium-based composite material, which requires the addition of a large amount of expensive high-thermal-conductivity second phase such as graphene and diamond, resulting in high cost of the composite material and poor mechanical properties. At the same time, the utilization efficiency of the high-thermal-conductivity second phase (the improvement of the thermal conductivity per mass fraction of the reinforcing phase, i.e. the improvement of the thermal conductivity divided by the mass fraction of graphene) is limited, and the improvement of the thermal conductivity of the composite material is also limited. The present application provides a preparation method of a titanium-based composite material with a graphene-Ti dual-continuous structure.

[0007] A preparation method of a titanium-based composite material with a graphene-Ti dual-continuous structure is carried out according to the following steps:

[0008] I. A titanium-based framework model for electrophoretic deposition of graphene is established according to actual needs, and then a titanium-based framework with a corresponding three-dimensional structure is prepared using selective laser melting technology. The prepared titanium-based framework with a three-dimensional structure is placed in a hydrofluoric acid solution to remove the surface oxide scale, and then it is placed in alcohol for ultrasonic cleaning to remove impurities;

[0009] II. Graphene nanosheets and Mg(NO3)2 are added to isopropyl alcohol and ultrasonically treated to make Mg2+ ions adsorbed on the surface of graphene and uniformly dispersed in isopropyl alcohol, obtaining a graphene isopropyl alcohol dispersion; 2+

[0010] III. The titanium-based framework is fixed to the negative electrode of the power supply, the iron electrode plate is fixed to the positive electrode of the power supply, and the graphene isopropyl alcohol dispersion is placed in the power supply for electrophoretic deposition, obtaining a framework with electrophoretically deposited graphene;

[0011] IV. The framework with electrophoretically deposited graphene is placed in a graphite mold for spark plasma sintering, titanium-based powder material is poured into the graphite mold, and the composite powder is fully filled into the interior of the titanium-based framework with deposited graphene by slight vibration, and then spark plasma sintering is performed to prepare a graphene / Ti-based composite material;

[0012] V. After the heat preservation is completed, the furnace is cooled to below 100℃ in a vacuum environment, and the graphene-reinforced titanium-based composite material with a dual-continuous structure is prepared.

[0013] ​The present application has the following beneficial effects: the present application realizes the distribution of the connected configuration of graphene in the titanium-based composite material, and the configuration of the connected graphene can be regulated by changing the titanium-based frame structure for electrophoretic deposition of graphene. The prepared composite material has a large increase in thermal conductivity and strength compared with the alloy under the premise of extremely low graphene content, realizes high utilization of expensive graphene nanosheets, and reduces the raw material cost of the high-thermal-conductivity titanium-based composite material. The thermal conductivity of the graphene / Ti-based composite material prepared by taking pure titanium as the substrate is increased from about 12 W / (m·K) of pure titanium to about 23 W / (m·K), which is nearly doubled, and the strength is slightly improved compared with the pure titanium substrate.

[0014] In order to overcome the problem that graphene and Ti will have a serious interface reaction at high temperature, the structure is destroyed, and excellent thermal-mechanical properties are lost, so as to obtain a high-performance titanium-based composite material that can be applied in a high-temperature environment, a high-temperature titanium alloy can be selected as the substrate, and a TiB reinforcing phase is introduced into the material, and the graphene used in the present application is surface modified, such as surface modification with W, Ni, Cu and the like. Experiments show that surface modification will not affect the electrophoretic deposition of graphene on the surface of the titanium-based frame. Selecting W element surface modified graphene, filling (TA15-1vol.%TiB) composite powder, and preparing graphene / (TA15-TiB) composite material with double connected structure according to the above method, the tensile strength of the material is 1050 MPa, which exceeds the sintered and forged commercial TA15, and the material still retains a fracture strain of about 0.03. When the graphene content in the titanium-based composite material with a connected structure is less than 0.2wt.%(the total mass of graphene in the electrophoretic liquid is about 0.2wt.%of the mass of the sintered composite material, and part of the graphene remains in the electrophoretic liquid after the electrophoresis is completed), the thermal conductivity exceeds 13 W / (m·K), which is nearly 1 times higher than that of the alloy. Compared with the main high-thermal-conductivity titanium-based composite materials at the present stage, the material designed in the present application has a certain room temperature tensile plasticity, and the graphene utilization rate is greatly increased from 0.3-0.6 W / (m·K) per mass fraction of graphene to about 30 W / (m·K) per mass fraction of graphene. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 It is a process flow chart of a preparation method of a titanium-based composite material with graphene-Ti double connected structure;

[0016] Figure 2 It is a macroscopic morphology diagram of the TA15 frame before electrophoretic deposition in Example 1;

[0017] Figure 3 It is a macroscopic morphology diagram of the TA15 frame after electrophoretic deposition in Example 1;

[0018] Figure 4 Frame surface topography map after electrophoretic deposition in Example 1;

[0019] Figure 5 Frame surface W-modified graphene nanosheet topography map in Example 1;

[0020] Figure 6 Figure 5 Corresponding W element distribution map;

[0021] Figure 7 Low-magnification SEM photo of bi-continuous structure graphene reinforced titanium matrix composite material in Example 1;

[0022] Figure 8 SEM photo of W element surface-modified graphene nanosheet in the composite material prepared in Example 1;

[0023] Figure 9 Figure 8 Corresponding W element distribution map;

[0024] Figure 10 Engineering stress-strain comparison diagram of TA15 frame and bi-continuous structure graphene reinforced titanium matrix composite material in Example 1; wherein 1 represents TA15 alloy prepared using the same process as a control group, and 2 represents bi-continuous structure graphene reinforced titanium matrix composite material;

[0025] Figure 11 Surface topography map of graphene / Ti composite material prepared in Example 2;

[0026] Figure 12 Interface topography map of graphene / Ti composite material prepared in Example 2;

[0027] Figure 13 Corresponding C element distribution map of Example 12;

[0028] Figure 14 Engineering stress-strain comparison diagram of pure titanium frame and bi-continuous structure graphene reinforced titanium matrix composite material in Example 2; wherein 1 represents pure titanium prepared using the same process as a control group, and 2 represents bi-continuous structure graphene reinforced titanium matrix composite material. DETAILED DESCRIPTION

[0029] The technical solution of the present application is not limited to the specific embodiments listed below, but also includes any combination between the specific embodiments.

[0030] Specific embodiment one: the preparation method of the titanium-based composite material with graphene-Ti bi-continuous structure in this embodiment is specifically carried out according to the following steps:

[0031] ​​One, a titanium-based framework model for electrophoretic deposition of graphene is established according to actual needs, and then a titanium-based framework with a corresponding three-dimensional structure is prepared by using a selective laser melting technology; the prepared titanium-based framework with a three-dimensional structure is placed in a hydrofluoric acid solution to remove the surface oxide scale, and then is placed in alcohol for ultrasonic cleaning to remove impurities;

[0032] Two, graphene nanosheets and Mg(NO3)2 are added to isopropyl alcohol for ultrasonic treatment, so that Mg 2+ ions are adsorbed on the surface of graphene and uniformly dispersed in isopropyl alcohol to obtain a graphene isopropyl alcohol dispersion;

[0033] Three, the titanium-based framework is fixed at the negative electrode of a power supply, an iron electrode plate is fixed at the positive electrode of the power supply, and the graphene isopropyl alcohol dispersion is placed in the power supply for electrophoretic deposition to obtain a framework of electrophoretically deposited graphene;

[0034] Four, the framework of electrophoretically deposited graphene is placed in a graphite mold for discharge plasma sintering, titanium-based powder material is poured into the graphite mold, and the composite powder is fully filled into the interior of the titanium-based framework of deposited graphene by slight vibration, and then discharge plasma sintering is performed to prepare a graphene / Ti-based composite material;

[0035] Five, after the end of heat preservation, the furnace is cooled to below 100℃ in a vacuum environment, and the graphene reinforced titanium-based composite material with a double-connected structure is taken out, thereby achieving the preparation of the graphene reinforced titanium-based composite material with a double-connected structure.

[0036] The embodiment is oriented to the urgent demand of an aircraft surface hot end component for a high-thermal-conductivity titanium-based composite material, and is directed to the key scientific problem of the inversion of the thermal conductivity performance and strength of the composite material. A graphene / (TA15-TiB) composite material with a double-connected structure is designed to synergistically improve the thermal conductivity performance and strength of the composite material under the premise of low graphene content.

[0037] The structure of the embodiment can be customized according to needs, and is not limited to a certain specific structure. The structure can be selected from a cubic framework structure, a hexagonal honeycomb structure, and a complex topological structure, etc.

[0038] The embodiment first electrophoretically deposits W-modified graphene on a titanium-based framework, and then fills the framework with (TA15-TiB) composite powder to realize the preparation of a double-connected graphene / (TA15-TiB) composite material by discharge plasma sintering. The connected graphene constitutes a “fast channel” for phonon transmission to improve the strength of the composite material and improve the thermal conductivity of the composite material; the nano TiB whiskers in the matrix realize the refinement of the composite material organization and the improvement of the strength; and the titanium-based framework can play a toughening role in improving the deformation capacity of the composite material.

[0039] The embodiment adopts the way of electrophoretic deposition of graphene to precisely construct a graphene network on a titanium-based framework, and then fills TA15-TiB composite powder for sintering to form a graphene-Ti double-connected structure. This unique architecture avoids the drawbacks of adding a large amount of graphene in traditional methods to improve thermal conductivity. In the past, a large amount of graphene, diamond and other high-thermal-conductivity second phases were added, which inevitably increased the cost and easily damaged the connectivity of the matrix. The double-connected structure can build an efficient heat conduction path with less graphene, and the heat can be quickly conducted along the graphene network, improving the graphene thermal conductivity efficiency, thereby improving the thermal conductivity efficiency, reducing the dependence on expensive high-thermal-conductivity phases, reducing the cost while maintaining the continuity of the material matrix, allowing the titanium alloy matrix and the reinforcing phase to work together to achieve a synergistic improvement in strength and thermal conductivity. The titanium-based framework prepared by selective laser melting technology provides a customized three-dimensional structural support for graphene deposition and composite powder filling. Compared with unordered addition of high-thermal-conductivity phases, this framework allows the graphene and composite powder to be in their proper place, ensuring a reasonable stress distribution when the material is under stress, thereby enhancing the load-carrying capacity of the composite material and improving the mechanical properties.

[0040] In the embodiment, the graphene nanosheets are modified by W, and the modified graphene nanosheets adsorb Mg 2+ ions and are uniformly dispersed in isopropyl alcohol. The modification improves the stability of the graphene itself, inhibits its adverse reaction with Ti at high temperatures, and preserves the excellent thermal and mechanical properties of the graphene. The uniformly dispersed graphene can be more finely and uniformly integrated into the system, avoiding local stress concentration and uneven thermal conductivity caused by agglomeration. In this way, the graphene can maximize its effect of enhancing thermal conductivity and mechanical properties at a low content, avoiding the destruction of the matrix connectivity and the damage to the mechanical properties caused by excessive addition in traditional methods, and achieving a synergistic optimization of thermal conductivity and strength.

[0041] In the embodiment, the framework of electrophoretically deposited graphene and TA15-TiB composite powder are sintered by spark plasma sintering. This process can densify in a short time and at a low temperature, reducing the damage to the microstructure of the material caused by high-temperature and long-time sintering; inhibiting abnormal grain growth and maintaining the state of fine grains that are beneficial to strength, and improving thermal conductivity with the help of the graphene network, avoiding the intrinsic inversion phenomenon caused by considering thermal conductivity and strength in traditional processes, and achieving a synergistic improvement in both. The vacuum furnace cooling process after holding can reduce defects such as micro-cracks caused by thermal stress during material cooling, ensuring the integrity of the material, making the thermal conduction path complete and the internal structure stable, and further consolidating the synergistic effect of the thermal and mechanical properties of the composite material.

[0042] Specific embodiment two: the difference between this embodiment and specific embodiment one is that the process parameters of the laser melting technology in step one are as follows: the laser spot size is 100 μm, the set printing layer thickness is 0.03 mm, the laser scanning interval is 90 μm, the laser power is 155 W, and the scanning speed is 1200 mm / s. The others are the same as specific embodiment one.

[0043] Specific embodiment three: the difference between this embodiment and specific embodiment one is that the height of the titanium-based frame in step one is 3-9 mm, and the frame diameter is 5-40 mm; the volume concentration of the hydrofluoric acid solution is 5-15%, and the pickling time of the hydrofluoric acid solution is 0.5-2 min. The others are the same as specific embodiment one.

[0044] Specific embodiment four: the difference between this embodiment and specific embodiment one is that the graphene-based nanosheet in step two is a graphene nanosheet or a surface-modified graphene nanosheet; the thickness of the graphene-based nanosheet is 1-3 nm, and the sheet diameter is 2-3 μm. The others are the same as specific embodiment one.

[0045] Specific embodiment five: the difference between this embodiment and specific embodiment one is that the mass ratio of the graphene-based nanosheet to Mg(NO3)2 in step two is 1:1-2. The others are the same as specific embodiment one.

[0046] Specific embodiment six: the difference between this embodiment and specific embodiment one is that the ultrasonic treatment time in step two is 0.5-1 h. The others are the same as specific embodiment one.

[0047] Specific embodiment seven: the difference between this embodiment and specific embodiment one is that the concentration of graphene in the graphene isopropanol dispersion solution in step two is 0.5-3 mg / mL. The others are the same as specific embodiment one.

[0048] Specific embodiment eight: the difference between this embodiment and specific embodiment one is that the process parameters of the electrophoretic deposition in step three are as follows: the electrophoretic voltage is 40-60 V, and the electrophoretic duration is 20-80 min. The others are the same as specific embodiment one.

[0049] Specific embodiment nine: the difference between this embodiment and specific embodiment one is that the process parameters of the spark plasma sintering in step four are as follows: the sintering temperature is 1000-1100 ℃, the holding time is 3-10 min, and the pressure is 60 MPa. The others are the same as specific embodiment one.

[0050] Specific embodiment ten: the difference between this embodiment and specific embodiment one is that the titanium-based powder material in step four is a titanium alloy powder or a titanium-based composite powder; the particle size distribution of the titanium-based powder material is 15-53 μm. The others are the same as specific embodiment one.

[0051] The beneficial effects of the present application are verified by the following examples:

[0052] Example 1: A preparation method of a titanium-based composite material with graphene-Ti double-connected structure is specifically performed according to the following steps:

[0053] I. A titanium-based framework model for electrophoretic deposition of graphene is established according to actual needs, and then a titanium-based framework with a corresponding three-dimensional structure is prepared by using a selective laser melting technology. In this embodiment, a diamond lattice structure is selected to balance the heat conduction and mechanical properties, and the material used is TA15 alloy. The process parameters of the laser melting technology are as follows: the laser spot size is 100 μm, the set printing layer thickness is 0.03 mm, the laser scanning interval is 90 μm, the laser power is 155 W, and the scanning speed is 1200 mm / s. The height of the titanium-based framework is 9 mm, and the framework diameter is 200 μm. The prepared titanium-based framework is placed in a hydrofluoric acid solution for pickling, then taken out of the acid solution, washed with alcohol, and then placed in alcohol for ultrasonic cleaning. The volume concentration of the hydrofluoric acid solution is 5-15%, and the pickling time of the hydrofluoric acid solution is 0.5-2 min.

[0054] II. W-modified graphene nanosheets with a thickness of 1-3 nm and a flake diameter of 2-3 μm and Mg(NO3)2 are added to isopropanol and ultrasonically treated for 0.5 h to make the graphene surface adsorb Mg2+ and uniformly disperse in isopropanol to obtain a graphene isopropanol dispersion. The mass ratio of the W-modified graphene nanosheet to Mg(NO3)2 is 1:1. The concentration of the graphene in the graphene isopropanol dispersion is 1 mg / mL. 2+

[0055] III. The titanium-based framework is fixed to the negative electrode of a power supply, an iron electrode plate is fixed to the positive electrode of the power supply, and then the graphene isopropanol dispersion is placed in the power supply for electrophoretic deposition to obtain a framework with electrophoretically deposited graphene. The process parameters of the electrophoretic deposition are as follows: the electrophoretic voltage is 50 V, and the electrophoretic time is 40 min.

[0056] IV. The framework with electrophoretically deposited graphene is placed in a graphite mold for spark plasma sintering, TA15-TiB composite powder is poured into the graphite mold, and the composite powder is slightly vibrated to fully fill the inside of the titanium-based framework with deposited graphene, and then spark plasma sintering is performed to prepare a graphene / (TA15-TiB) composite material. The process parameters of the spark plasma sintering are as follows: the sintering temperature is 1100℃, the holding time is 3 min, and the pressure is 60 MPa. The volume fraction of TiB in the TA15-TiB composite powder is 1%, and the particle size distribution is 15-53 μm.

[0057] V. After the holding is completed, the furnace is cooled to below 100℃ in a vacuum environment, and then taken out to realize the preparation of a graphene-reinforced titanium-based composite material with a double-connected structure.​

[0058] The preparation of the W-modified graphene nanoplatelets in this embodiment is specifically performed according to the following steps:

[0059] I. Graphene nanoplatelets with a particle size of 1-5 μm and a thickness of 5-20 nm are washed with distilled water and dried, and then are placed into a 10% hydrofluoric acid solution for ultrasonic dispersion for 30 min, so that the graphene is fully dispersed in the solution and fully contacts with the HF to functionalize the surface of the graphene. After ultrasonic dispersion, the graphene is washed with distilled water again and dried to obtain graphene with a functionalized surface;

[0060] II. NaCl and KCl are mechanically mixed uniformly at a molar ratio of 1:1 to obtain a mixed salt;

[0061] III. WO3 particles and the graphene with a functionalized surface are mechanically mixed uniformly at a molar ratio of 1:8 to obtain a mixed powder. The mixed powder is laid on the bottom of a crucible, and the mixed salt is covered on the surface of the mixed powder to obtain a crucible containing the mixed salt and the mixed powder. The volume ratio of the mixed powder to the mixed salt is 1:2;

[0062] IV. The crucible containing the mixed salt and the mixed powder is placed into a heat treatment furnace, the reaction temperature is 1000°C, and the heat preservation time under an argon atmosphere is 30 min for surface modification of the graphene. The WO3 particles react with the graphene to reduce W element to nucleate and grow on the surface of the graphene, so that the W surface modification is realized. After the reaction, the furnace is cooled to below 100°C under an argon atmosphere, and the crucible is taken out;

[0063] V. The reactants in the crucible are taken out, washed with distilled water, filtered with filter paper, and the salt in the mixed powder is completely removed. The graphene with W element surface modification is separated and dried, so that the W element surface modified graphene nanoplatelets prepared by the molten salt method are completed.

[0064] The tensile strength of the graphene / (TA15-TiB) composite material with a double-connected structure obtained in this embodiment is 1050 MPa, which exceeds that of the sintered and forged commercial TA15, and still retains a fracture strain of about 0.03. When the graphene content in the titanium-based composite material with a connected structure is less than 0.2 wt.% (the total mass of the graphene in the electrophoretic fluid to the mass of the sintered composite material is about 0.2 wt.%), the thermal conductivity exceeds 13 W / (m·K), which is nearly 1 time of the alloy.

[0065] It can be seen from Figure 2 that the titanium-based framework does not have obvious deformation and cracks, which indicates that the selected printing parameters are reasonable, and the preparation of titanium alloy with a complex three-dimensional configuration can be realized. From Figure 3It can be seen from FIG. 2 that electrophoretic deposition can make graphene uniformly adhere to the surface of the complex three-dimensional framework, proving that the design and regulation of graphene configuration by electrophoretic deposition of graphene on the framework are scientific and feasible. Figure 4 and Figure 5 It can be seen from FIG. 3 that the graphene on the surface of the framework is uniformly distributed, indicating that the method can introduce a connected graphene structure in the titanium-based composite material, and the connected graphene is uniformly distributed and has a uniform thickness; and proving that the W-modified graphene can be uniformly adsorbed on the surface of the titanium-based framework. Figure 6 It can be seen from FIG. 4 that the W-modified graphene is uniformly distributed. Figure 7 It can be seen from FIG. 5 that there is a graphene-Ti double-connected structure in the sintered material. Figure 8 and Figure 9 It can be seen from FIG. 6 and FIG. 7 that the graphene does not have a serious interface reaction during the sintering process, and the distribution of W elements proves the existence of the W-modified graphene. Figure 10 It can be seen from FIG. 8 that compared with the TA15 alloy, the strength of the composite material is greatly improved, and it also has certain room temperature plasticity. It is indicated that the composite material prepared by the method has excellent mechanical properties.

[0066] Embodiment 2: A method for preparing a titanium-based composite material with a graphene-Ti double-connected structure is specifically performed according to the following steps:

[0067] I. A titanium-based framework model for electrophoretic deposition of graphene is established according to actual needs, and then a titanium-based framework with a corresponding three-dimensional structure is prepared by using a selective laser melting technology. In this embodiment, a cubic framework structure is selected to balance the heat conduction and mechanical properties, and pure Ti is used as the material. The process parameters of the laser melting technology are as follows: the laser spot size is 100 μm, the set printing layer thickness is 0.03 mm, the laser scanning interval is 90 μm, the laser power is 155 W, and the scanning speed is 1200 mm / s. The height of the titanium-based framework is 6 mm, and the framework diameter is 20 mm. The prepared titanium-based framework is placed in a hydrofluoric acid solution for pickling, then taken out of the acid solution, washed with alcohol, and then placed in alcohol for ultrasonic cleaning. The volume concentration of the hydrofluoric acid solution is 5-15%, and the pickling time of the hydrofluoric acid solution is 0.5-2 min.

[0068] II. Graphene nanosheets with a thickness of 1-3 nm and a flake diameter of 2-3 μm and Mg(NO3)2 are added to isopropyl alcohol and ultrasonically treated for 0.5 h to make the graphene surface adsorb Mg 2+ ions and uniformly disperse in isopropyl alcohol to obtain a graphene isopropyl alcohol dispersion. The mass ratio of the graphene nanosheet to Mg(NO3)2 is 1:1. The concentration of the graphene in the graphene isopropyl alcohol dispersion is 1 mg / mL.

[0069] 3. Fix the titanium-based framework to the negative terminal of the power supply and the iron plate to the positive terminal of the power supply. Place the framework in the graphene isopropanol dispersion for electrophoretic deposition to obtain the electrophoretically deposited graphene framework. The electrophoretic deposition process parameters are: electrophoretic voltage of 50V and electrophoresis time of 40min.

[0070] 4. The electrophoretically deposited graphene framework is placed in a graphite mold for spark plasma sintering. Pure Ti powder is poured into the graphite mold and gently vibrated to ensure that the composite powder fully fills the interior of the titanium-based framework of the deposited graphene. Subsequently, spark plasma sintering is performed to prepare the graphene / Ti composite material. The process parameters for spark plasma sintering are: sintering temperature of 1100℃, holding time of 3 min, and pressure of 60 MPa. The particle size distribution of the pure Ti powder is 15–53 μm.

[0071] 5. After the heat preservation is completed, the material is cooled in a vacuum environment to below 100°C and then removed to achieve the preparation of graphene-reinforced titanium-based composite material with a double-connected structure.

[0072] Figure 11 The image shows the surface morphology of the graphene / Ti composite material prepared in Example 2; it can be seen from the image that the graphene in the composite material is continuously wrapped around the framework surface.

[0073] Figure 12 The image shows the interface morphology of the graphene / Ti composite material prepared in Example 2; the thickness of the graphene layer in the image is approximately 2 micrometers.

[0074] Figure 13 The graph shows the C element distribution corresponding to Example 12; the C element distribution in the graph visually indicates the specific distribution of graphene.

[0075] Figure 14 The image shows a comparison of the engineering stress-strain of the pure titanium frame and the double-connected graphene-reinforced titanium matrix composite material in Example 2; where 1 represents pure titanium prepared using the same process as a control group, and 2 represents the double-connected graphene-reinforced titanium matrix composite material; the tensile curves show that the composite material has excellent mechanical properties, with a certain degree of strength improvement, while retaining extremely high elongation.

Claims

1. A method for preparing a titanium-based composite material having a graphene-Ti bi-continuous structure, characterized by The preparation method of the titanium-based composite material with the graphene-Ti double-connected structure is specifically performed according to the following steps: Step one: a titanium-based framework model for electrophoretic deposition of graphene is established according to actual needs, and then a titanium-based framework with a corresponding three-dimensional structure is prepared by using a selective laser melting technology; the prepared titanium-based framework with the three-dimensional structure is placed in a hydrofluoric acid solution to remove the surface oxide skin, and then is placed in alcohol for ultrasonic cleaning to remove impurities; II. adding graphene-based nanosheets and Mg(NO3)2 into isopropyl alcohol and ultrasonic treating, so that Mg ions are adsorbed on the surface of graphene and uniformly dispersed in isopropyl alcohol to obtain a graphene isopropyl alcohol dispersion; the graphene-based nanosheets are graphene nanosheets or surface-modified graphene nanosheets; the thickness of the graphene-based nanosheets is 1-3 nm, and the flake diameter is 2-3 μm; 2+ II. adding graphene-based nanosheets and Mg(NO3)2 into isopropyl alcohol and ultrasonic treating, so that Mg ions are adsorbed on the surface of graphene and uniformly dispersed in isopropyl alcohol to obtain a graphene isopropyl alcohol dispersion; the graphene-based nanosheets are graphene nanosheets or surface-modified graphene nanosheets; the thickness of the graphene-based nanosheets is 1-3 nm, and the flake diameter is 2-3 μm; Step three: the titanium-based framework is fixed at a negative electrode of a power supply, an iron electrode plate is fixed at a positive electrode of the power supply, and the graphene isopropyl alcohol dispersion liquid is placed in the power supply for electrophoretic deposition to obtain a framework of electrophoretically deposited graphene; the process parameters of the electrophoretic deposition are that the electrophoretic voltage is 40-60 V, and the electrophoretic time is 20-80 min; Step four: the framework of the electrophoretically deposited graphene is placed in a graphite mold for discharge plasma sintering, titanium-based powder material is poured into the graphite mold, and the composite powder is fully filled into the interior of the titanium-based framework of the deposited graphene by slight vibration, and then discharge plasma sintering is performed to prepare a graphene / Ti-based composite material; the titanium-based powder material is titanium alloy powder or titanium-based composite powder; the particle size distribution of the titanium-based powder material is 15-53 μm; Step five: after the heat preservation is completed, the furnace is cooled to below 100℃ under vacuum, and then the graphene reinforced titanium-based composite material with the double-connected structure is obtained.

2. The method of claim 1, wherein the method further comprises the step of: The process parameters of the laser melting technology in step one are that the laser spot size is 100 μm, the set printing layer thickness is 0.03 mm, the laser scanning interval is 90 μm, the laser power is 155 W, and the scanning speed is 1200 mm / s. ​ 3. The method of claim 1, wherein the method further comprises the step of: The height of the titanium-based framework in step one is 3-9 mm, and the framework diameter is 5-40 mm; the volume concentration of the hydrofluoric acid solution is 5-15%, and the pickling time of the hydrofluoric acid solution is 0.5-2 min. ​ 4. The method of claim 1, wherein the method further comprises the step of: The mass ratio of the graphene-based nanosheet to Mg(NO3)2 in step two is 1:1-2. ​ 5. The method of claim 1, wherein the method further comprises the step of: The ultrasonic treatment time in step two is 0.5-1 h. ​ 6. The method of claim 1, wherein the method further comprises the step of: The concentration of the graphene in the graphene isopropyl alcohol dispersion liquid in step two is 0.5-3 mg / mL. ​ 7. The method of claim 1, wherein the method further comprises the step of: The process parameters of the discharge plasma sintering in step four are that the sintering temperature is 1000-1100℃, the heat preservation time is 3-10 min, and the pressure is 60 MPa. ​

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