Cu-Te / ZnO-coated Gr composite material and preparation method thereof

Abstract

The invention relates to a Cu-Te / ZnO (at) Gr composite material and a preparation method thereof. The preparation method comprises the following steps: step 1, pre-alloying copper and tellurium; step 2, supersonic gas atomization powder preparation; 3, zinc oxide in-situ growth, wherein the surface of the Cu-Te pre-alloyed powder obliquely grows and is coated with a ZnO nanoneedle array; 4, antioxidant composite treatment is conducted, specifically, the ZnO-coated Cu-Te powder prepared in the step 3 is soaked in an ethanol solution containing 0.8 wt% of an organic borosilicate complexing agent; and step 5, chemically bonding graphene, and treating by adopting a pH response type graphene oxide dispersion liquid. By adopting the technical scheme, the obliquely growing ZnO nanoneedle transition layer and the graphene shell layer are constructed to synergistically form a three-dimensional anchoring structure, chemical bonding with graphene is enhanced, and on the basis of the low-temperature in-situ reaction of the zinc-ammonium complexing solution and the synergistic effect of the organic boron-silicon complexing agent, a compact glass phase is formed at a high temperature, so that the performance of the composite material is improved. The volatilization rate of the Te element is reduced, and a Si-O-Zn covalent bond is formed between ZnO and graphene in combination with three-stage pH regulation.

Description

Technical Field

[0001] This invention belongs to the field of metal matrix composite technology, and particularly relates to a Cu-Te / ZnO@Gr composite material and its preparation method. Background Technology

[0002] As electronic devices develop towards higher power density, copper-based composite materials face severe challenges in terms of conductivity, strength, and high-temperature stability.

[0003] There is a ball milling method for preparing graphene / copper composite materials, which involves mixing graphene and copper powder using ball milling. However, this method is prone to causing graphene sheet breakage, and the CuO impurity layer generated at the interface significantly reduces the conductivity (only 78% IACS).

[0004] While the copper tellurium alloy proposed in the patent with patent number US2021037152A1 has a certain high-temperature strength, the Te element has a volatilization rate of more than 12wt% / h above 600℃, and the introduction of the aluminum oxide coating leads to a 3-fold increase in interfacial thermal resistance.

[0005] In addition, the patent with patent number JP2020156782A uses CVD to grow graphene coating at a high temperature of 1050℃, which causes abnormal growth of copper grains (average grain size >50μm), resulting in a decrease in material strength to below 420MPa; none of the above methods can take into account low temperature processing adaptability, interfacial bonding strength and elemental stability. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art by providing a Cu-Te / ZnO@Gr composite material and its preparation method, which solves the problems of graphene structural damage and interface impurities, high-temperature volatilization and antioxidant failure of Te element, and matrix performance degradation caused by high-temperature processes.

[0007] The technical solution of this invention: A method for preparing Cu-Te / ZnO@Gr composite material, comprising:

[0008] Step 1: Copper-tellurium pre-alloying, with materials prepared according to an atomic ratio of Cu:Te = 82.5:17.5, and 0.3wt% rare earth yttrium added as a grain boundary purifier, at a pressure ≤10. -3 Vacuum induction melting is carried out under Pa conditions;

[0009] Step 2: The alloy obtained in Step 1 is subjected to supersonic gas atomization to obtain Cu-Te pre-alloyed powder with a particle size D50 = 15 μm.

[0010] Step 3: In-situ growth of zinc oxide. The Cu-Te pre-alloyed powder obtained in step 2 is immersed in a zinc ammonium complex solution and deposited using pulsed ultrasound-assisted deposition to grow and coat a ZnO nanoneedle array on the surface of the Cu-Te pre-alloyed powder.

[0011] Step 4: Antioxidant composite treatment. The ZnO-coated Cu-Te powder obtained in Step 3 is immersed in an ethanol solution containing 0.8-1.2 wt% organoborosilicate composite agent and heat-treated in a reducing atmosphere to form an antioxidant interface layer. The organoborosilicate composite agent includes trimethyl borate and vinyltriethoxysilane.

[0012] Step 5: Graphene chemical bonding, using a pH-responsive graphene oxide (GO) dispersion for treatment. The dispersion is controlled by a pH-regulated grafting process, which includes:

[0013] In the first stage, the pH was maintained at 9.5 to allow GO to adsorb onto the surface of ZnO nanoneedles.

[0014] In the second stage, the pH was adjusted to 7.2, and a complex reducing agent of L-ascorbic acid and lipoic acid was added for reduction at 60°C.

[0015] In the third stage, the pH was adjusted to 5.8, and KH-550 silane coupling agent was introduced to achieve interfacial bridging, forming Si-O-Zn covalent bonds between ZnO and graphene.

[0016] Using the above technical solution, a three-level gradient process of vacuum melting-gas atomization powdering, ZnO nanoneedle array pulse electrodeposition, and finally pH-responsive graphene chemical bonding is used to construct a fully dense core-shell structure with Cu-Te alloy core, ZnO nanoneedle transition layer and graphene shell, thereby achieving multi-level synergistic enhancement from oxygen vacancy regulation to grain boundary purification.

[0017] By constructing a three-dimensional anchoring structure through the synergistic formation of a tilted-grown ZnO nanoneedle transition layer and a graphene shell, the chemical bonding with graphene is enhanced. Furthermore, based on the low-temperature in-situ reaction of the zinc ammonium complex solution and the synergistic effect of the organoborosilicate composite agent, a dense glassy phase is formed at 300-550℃, reducing the volatilization rate of Te. Combined with three-stage pH regulation (9.5 adsorption, then 7.2 selective reduction, and finally 5.8 covalent coupling), Si-O-Zn covalent bonds are formed between ZnO and graphene, achieving directional arrangement and coating of graphene. This results in improved electron mobility and enhanced interfacial bonding strength, breaking through the traditional inverse relationship between strength and conductivity in copper-based composite materials.

[0018] Another object of the present invention is to provide a Cu-Te / ZnO@Gr composite material, comprising a core, a ZnO nanoneedle transition layer, and a graphene shell;

[0019] Core: Cu-Te alloy;

[0020] ZnO nanoneedle transition layer: an array of tilted ZnO nanoneedles with a length of 150-200 nm, a diameter of 20-30 nm, and a tilt angle of 55-65°.

[0021] Graphene shell: 3-5 layers of graphene, connected to the ZnO nanoneedle transition layer via Si-O-Zn covalent bonds, with a Raman D / G peak intensity ratio ≤0.2.

[0022] Using the above technical solution, the graphene shell is interlocked with the ZnO nanoneedle transition layer through the Si-O-Zn bonding mechanism, which allows it to maintain its structural integrity during thermal cycling. Furthermore, by constructing an inclined ZnO nanoneedle transition layer (length 150-200nm, diameter 20-30nm, tilt angle 55-65°) to synergistically form a three-dimensional anchoring structure with the graphene shell, the chemical bonding with graphene is enhanced, while inhibiting Te volatilization and abnormal Cu grain growth. Moreover, the inclined ZnO nanoneedle transition layer can also be tightly bonded to the core of the Cu-Te alloy through the mechanical interlocking effect, effectively inhibiting interlayer delamination. Attached Figure Description

[0023] Figure 1 This is a flowchart of the preparation method of the present invention. Detailed Implementation

[0024] The technical solutions in this embodiment will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] This invention provides a method for preparing Cu-Te / ZnO@Gr composite materials, such as... Figure 1 As shown, prepare according to the following steps:

[0026] Step 1: Copper-tellurium pre-alloying

[0027] Pure copper and tellurium ingots were weighed according to an atomic ratio of Cu:Te = 82.5:17.5, and 0.3 wt% rare earth yttrium was added as a grain boundary purifier.

[0028] Pure copper is placed in a vacuum induction melting furnace and melted at 1250℃ and a vacuum degree ≤10-3Pa. Argon gas is introduced at a flow rate of 12L / min to stir and remove gaseous impurities.

[0029] After melting, the temperature is lowered to 980℃, and tellurium ingot and 0.3wt% Y2O3 are added to refine the grains. The mixture is kept at this temperature for 20 minutes. At 980℃, copper tellurium is solid, thus obtaining a copper tellurium alloy.

[0030] Step 2: Supersonic gas atomization powder production

[0031] After the alloy ingot is crushed, it is loaded into a gas atomization device and atomized under a nitrogen pressure of 8.5 MPa. The average grain size of the powder after atomization is 1.2 μm.

[0032] Step 3: In-situ growth of zinc oxide

[0033] Preparation of zinc ammonium complex solution: Zn 2+ Concentration 0.25 mol / L, NH3·H2O and Zn 2+ Molar ratio 4.2;

[0034] The Cu-Te powder obtained in step 2 was immersed in the prepared zinc ammonium complex solution, and deposition was assisted by 28kHz pulsed ultrasound (duty cycle 1:0.67) for 30 minutes to form an inclined ZnO nanoneedle array on the powder surface. The length of the inclined ZnO nanoneedle array was 180nm±20nm, the diameter was 25nm±5nm, and the tilt angle was 55-65°.

[0035] Step 4: Antioxidant Complex Treatment

[0036] Prepare an ethanol solution containing 0.8-1.2 wt% organoborosilicate composite agent, which includes trimethyl borate and vinyltriethoxysilane in a ratio of 3:1. In this embodiment, an ethanol solution containing 0.8 wt% organoborosilicate composite agent is selected.

[0037] ZnO-coated Cu-Te powder was impregnated in an ethanol solution containing 0.8 wt% organoborosilicate composite agent, and then subjected to constant temperature heat treatment at 380 °C for 25 min in a reducing atmosphere of 95% N2-5% H2 (v / v). During this process, the organoborosilicate composite agent formed a dense glassy phase at high temperature, which reduced the volatilization rate of Te to 0.03 wt% / h, ultimately forming a dense glassy phase interface layer as an antioxidant interface layer.

[0038] Step 5: Graphene chemical bonding

[0039] A pH-responsive graphene oxide (GO) dispersion with a carboxyl group content of 1.2 mmol / g was used. The pH was controlled through a grafting process, which included three stages:

[0040] First stage: Immerse the powder in a pH-responsive graphene oxide (GO) dispersion with pH=9.5 and maintain for 15 minutes. Add NH3·H2O to the GO dispersion to ionize the carboxyl groups and adsorb them onto the surface of ZnO nanoneedles.

[0041] Second stage: Adjust the pH to 7.2, add a composite reducing agent of L-ascorbic acid (0.1g / mL) and lipoic acid (0.05g / mL), and carry out the reduction reaction at 60℃ for 30min.

[0042] The third stage: Adjust the pH to 5.8, introduce KH-550 silane coupling agent (concentration 1.5 vol%) and react with KH-550 silane coupling agent to form Si-O-Zn covalent bonds, and finally obtain a composite material with 3-5 layers of graphene coating.

[0043] The present invention also provides a Cu-Te / ZnO@Gr composite material prepared by the above preparation method, comprising a core, a ZnO nanoneedle transition layer and a graphene shell;

[0044] Core: Cu-Te alloy;

[0045] ZnO nanoneedle transition layer: A tilted ZnO nanoneedle array with a length of 150-200 nm, a diameter of 20-30 nm, and a tilt angle of 55-65°. The surface oxygen vacancy concentration of the ZnO nanoneedle transition layer reaches 1.8 × 10¹¹. 8 cm -3 ;

[0046] Graphene shell: 3-5 layers of graphene with an interlayer spacing of 0.34-0.38 nm, connected to the ZnO nanoneedle transition layer by Si-O-Zn covalent bonds, Raman D / G peak intensity ratio ≤0.2, conductivity ≥95% IACS, tensile strength ≥650MPa.

[0047] The graphene shell is interlocked with the ZnO nanoneedle transition layer through a Si-O-Zn bonding mechanism, which allows it to maintain its structural integrity during thermal cycling. Furthermore, by constructing an inclined ZnO nanoneedle transition layer, it synergistically forms a three-dimensional anchoring structure with the graphene shell, enhancing the chemical bonding with graphene while suppressing Te volatilization and abnormal Cu grain growth. Moreover, the inclined ZnO nanoneedle transition layer can also be tightly bonded to the core of the Cu-Te alloy through a mechanical interlocking effect, effectively suppressing interlayer delamination.

[0048] Antioxidant performance verification

[0049] Experimental methods

[0050] Test 1: The traditional Cu-Te alloy and the material of this invention were oxidized at 520℃ for 100h to increase their weight, and the weight gain per unit area was tested.

[0051] Test 2: Salt spray tests were conducted on traditional Cu-Te alloys and the material of this invention to test the degree of corrosion weight loss;

[0052] In this invention, an organoborosilicate composite agent is used for antioxidant composite treatment, which causes the material to form a dense glass phase at high temperature, reducing the Te volatilization rate to 0.03 wt% / h. According to the above test results, the oxidation weight gain of the material of this invention is much lower than that of traditional Cu-Te alloys, and the corrosion weight loss in the salt spray test is significantly less than that of traditional Cu-Te alloys. Therefore, the antioxidant properties of the composite material of this invention are significantly improved.

[0053] Conductivity and mechanical strength performance verification

[0054] The conductivity, tensile strength, and interfacial bonding strength of the material of this invention and the graphene / copper composite material prepared by the prior art were tested experimentally as comparative examples.

[0055] Among them, the comparative example uses the graphene / copper composite material prepared by the ball milling method mentioned in the background art for testing;

[0056] Test results show that the conductivity, tensile strength, and interfacial bonding strength of the present invention are significantly improved compared with the materials prepared by ball milling and mixing graphene and copper powder in the prior art.

[0057] High-temperature service verification

[0058] The composite powder was hot-pressed into electrode material, which was then sintered at 50 MPa and 650 °C.

[0059] In a high-temperature sulfide environment at 850℃, the conductivity retention rate is still 96.3% after 100 hours, which is a significant improvement compared to the 82% of the prior art. The material of this invention has good conductivity stability at high temperatures.

[0060] Creep resistance: Steady-state creep rate 2.1 × 10⁻⁶ -8 s -1 Compared to traditional materials, it is 8.7×10 -7 s -1 It has a lower creep rate and stronger creep resistance.

[0061] Extreme environment testing

[0062] Impact tests were conducted on the composite material of this invention and conventional materials at liquid nitrogen cryogenic conditions: the ambient temperature was cycled 100 times between -196℃ and 25℃, and the condition of the test materials was observed.

[0063] The material of this invention does not produce cracks, while traditional materials exhibit cracks ≥50μm.

[0064] Furthermore, the resistivity change rate of the material of this invention is <0.5%.

[0065] Therefore, in the low-temperature environment of liquid nitrogen, the resistivity of the material of the present invention changes little, the conductivity is stable, and there are no cracks generated as a whole, with strong interfacial bonding strength and elemental stability.

[0066] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the patent protection scope of the present invention.

Claims

1. A method for preparing a Cu-Te / ZnO@Gr composite material, characterized in that, include: Step 1: Copper-tellurium pre-alloying, with materials prepared according to an atomic ratio of Cu:Te = 82.5:17.5, and 0.3wt% rare earth yttrium added as a grain boundary purifier, at a pressure ≤10. -3 Vacuum induction melting is carried out under Pa conditions; Step 2: The alloy obtained in Step 1 is subjected to supersonic gas atomization to obtain Cu-Te pre-alloyed powder with a particle size D50=15μm. Step 3: In-situ growth of zinc oxide. The Cu-Te pre-alloyed powder obtained in step 2 is immersed in a zinc ammonium complex solution and deposited using pulsed ultrasound-assisted deposition to grow and coat a ZnO nanoneedle array on the surface of the Cu-Te pre-alloyed powder. Step 4: Antioxidant composite treatment. The ZnO-coated Cu-Te powder obtained in Step 3 is immersed in an ethanol solution containing 0.8-1.2 wt% organoborosilicate composite agent and heat-treated at 300-550°C in a reducing atmosphere to form an antioxidant interface layer. The organoborosilicate composite agent includes trimethyl borate and vinyltriethoxysilane. Step 5: Graphene chemical bonding, using a pH-responsive graphene oxide (GO) dispersion for treatment. The dispersion is controlled via a pH-regulated grafting process, which includes: In the first stage, the pH was adjusted to 9.5 to ionize the hydroxyl groups and adsorb them onto the surface of ZnO nanoneedles. In the second stage, the pH was adjusted to 7.2, and a complex reducing agent of L-ascorbic acid and lipoic acid was added for reduction at 60°C. In the third stage, the pH was adjusted to 5.8, and KH-550 silane coupling agent was introduced to achieve interfacial bridging, forming Si-O-Zn covalent bonds between ZnO and graphene.

2. The preparation method according to claim 1, characterized in that, The vacuum induction melting in step 1 includes melting pure copper at 1250℃ / 10⁻³ Pa, stirring and degassing with argon gas, then adding tellurium ingots and cooling to 980℃, adding 0.3wt% Y₂O₃ to refine the grains, and holding at the temperature.

3. The preparation method according to claim 1, characterized in that, In step 4, the mass ratio of trimethyl borate to vinyltriethoxysilane in the organoborosilicate composite is 3:

1.

4. The preparation method according to claim 1, characterized in that, In step 3, the concentration of Zn²⁺ in the zinc ammonium complex solution is 0.25 mol / L, the molar ratio of NH₃·H₂O to Zn²⁺ is 4.2, the frequency of the pulsed ultrasound is 28 kHz, and the duty cycle is 1:0.

67.

5. The preparation method according to claim 1, characterized in that, In step 5, the carboxyl content in the pH-responsive graphene oxide (GO) dispersion is 1.2 mmol / g.

6. The preparation method according to claim 1, characterized in that, In step 4, the heat treatment in the reducing atmosphere is performed at a constant temperature of 380°C in a reducing atmosphere with a volume fraction of 95% N2-5% H2.

7. A Cu-Te / ZnO@Gr composite material prepared by any one of the methods described in claims 1-6, characterized in that, It includes a core, a ZnO nanoneedle transition layer, and a graphene shell; Core: Cu-Te alloy; ZnO nanoneedle transition layer: an array of tilted ZnO nanoneedles with a length of 150-200 nm, a diameter of 20-30 nm, and a tilt angle of 55-65°. Graphene shell: 3-5 layers of graphene, connected to the ZnO nanoneedle transition layer via Si-O-Zn covalent bonds, with a Raman D / G peak intensity ratio ≤0.

2.

8. The composite material according to claim 7, characterized in that: The spacing between adjacent graphene layers in the graphene shell is 0.34-0.38 nm.

9. The composite material according to claim 7, characterized in that: Conductivity ≥95% IACS, tensile strength ≥650MPa.

10. The composite material according to claim 7, characterized in that: The surface oxygen vacancy concentration of the ZnO nanoneedle transition layer reaches 1.8 × 10¹. 8 cm⁻³.

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