阅读说明：本技术 一种Cu-(石墨烯/Al)多级层状复合材料及其制备方法 (Cu- (graphene/Al) multilevel layered composite material and preparation method thereof ) 是由 柳培 刘坤定 谢敬佩 王爱琴 王文焱 杨斌 侯博 马窦琴 毛志平 苌清华 陈艳芳 于 2020-11-27 设计创作，主要内容包括：本发明公开一种Cu-(石墨烯/Al)多级层状复合材料,其宏观上呈现Cu/Al层状结构,其中Cu层微观上呈现层状微纳米晶结构,Al层微观上呈现石墨烯/Al微纳米叠层结构。制备方法主要包括：利用球磨法获得片状Al和Cu粉末,以氧化石墨烯为原料,利用超声分散法获得单层石墨烯,并利用静电吸附法将单层石墨烯与片状Al粉末混合制备石墨烯/Al片状复合粉末；再将石墨烯/Al片状复合粉末与片状Cu粉末进行层状组装,经过真空热压烧结和热锻造制备出高致密化的Cu-(石墨烯/Al)多级层状复合材料。本发明通过向Cu/Al层状复合材料的Al层引入石墨烯以及宏微多尺度层状构型设计,制备出具有轻质、高强韧、高导热和高导电的Cu-(石墨烯/Al)多级层状复合材料,用于各种航空航天用轻质电热元器件。(The invention discloses a Cu- (graphene/Al) multistage layered composite material which macroscopically presents a Cu/Al layered structure, wherein a Cu layer microscopically presents a layered micro-nanocrystalline structure, and an Al layer microscopically presents a graphene/Al micro-nano laminated structure. The preparation method mainly comprises the following steps: the preparation method comprises the steps of obtaining flaky Al and Cu powder by using a ball milling method, obtaining single-layer graphene by using graphene oxide as a raw material and an ultrasonic dispersion method, and preparing graphene/Al flaky composite powder by mixing the single-layer graphene and the flaky Al powder by using an electrostatic adsorption method; and then carrying out layered assembly on the graphene/Al flaky composite powder and the flaky Cu powder, and preparing the high-densification Cu- (graphene/Al) multilevel layered composite material through vacuum hot-pressing sintering and hot forging. According to the invention, the Cu- (graphene/Al) multilevel layered composite material with light weight, high strength and toughness, high heat conductivity and high electric conductivity is prepared by introducing graphene into an Al layer of the Cu/Al layered composite material and designing a macro-micro multi-scale layered configuration, and is used for various light electric heating components for aerospace.)

1. A Cu- (graphene/Al) multilevel layered composite material is characterized in that: the composite material macroscopically presents a Cu/Al layered structure, wherein a Cu layer microscopically presents a layered micro-nanocrystalline structure, and an Al layer microscopically presents a graphene/Al micro-nano laminated structure.

2. The Cu- (graphene/Al) multilevel layered composite material according to claim 1, wherein: the thickness of the Cu layer and the thickness of the Al layer on the macro surface of the composite material are respectively 2-4 mm.

3. The Cu- (graphene/Al) multilevel layered composite according to claim 1 or 2, wherein: the scale of the layered micro-nanocrystalline structure of the Cu layer in the composite material is 100-300 nm.

4. The Cu- (graphene/Al) multilevel layered composite according to claim 1 or 2, wherein: the thickness of lamellar Al in the graphene/Al micro-nano laminated structure of the composite material Al layer is 100-300 nm, the graphene is a single layer or few layers, and the thickness is less than 15 nm.

5. The method for preparing the Cu- (graphene/Al) multilevel layered composite material according to any one of claims 1 to 4, wherein the method comprises the following steps: the method mainly comprises the following steps:

step one, preparing sheet metal powder: ball-milling Al powder and Cu powder by using a ball mill to prepare flaky Al powder and Cu powder with the thickness of 100-300 nm and the sheet diameter of 2-5 mu m;

step two, preparing a graphene dispersion liquid: adding graphene oxide into deionized water to obtain a graphene oxide solution, and then carrying out ultrasonic treatment to obtain a single-layer or few-layer graphene dispersion liquid;

step three, preparing graphene/aluminum flake composite powder: adding the flaky Al powder obtained in the step one and the graphene dispersion liquid obtained in the step two into absolute ethyl alcohol, stirring and mixing until the upper layer liquid of a beaker becomes colorless and transparent, then washing and filtering by using deionized water, vacuum drying to obtain graphene oxide/Al flaky composite powder, and then heating the graphene oxide/Al flaky composite powder under the hydrogen protective atmosphere to obtain graphene/Al flaky composite powder;

step four, layered self-assembly of the powder: uniformly paving the graphene/Al flaky composite powder obtained in the step three in a mold, sequentially stacking the graphene/Al flaky composite powder along the thickness direction, wherein the paving and stacking thickness is 19-21 mm, then uniformly paving the flaky Cu powder obtained in the step one above the graphene/Al flaky composite powder, and paving and stacking the flaky Cu powder above the graphene/Al flaky composite powder to obtain a Cu- (graphene/Al) layered powder blank;

step five, sintering preparation of the block composite material: performing discharge plasma sintering on the Cu- (graphene/Al) layered powder blank prepared in the fourth step to prepare a block Cu- (graphene/Al) multilevel layered composite material;

step six, hot rolling of the high-densification composite material: and (4) heating and rolling the block Cu- (graphene/Al) multistage layered composite material prepared in the fifth step to obtain the high-densification Cu- (graphene/Al) multistage layered composite material.

6. The preparation method of the Cu- (graphene/Al) multilevel layered composite material according to claim 5, wherein: the Al powder and the Cu powder selected in the first step are high-purity spherical Al powder and high-purity Cu powder respectively, the purities of the Al powder and the Cu powder are both 99.99%, and the average particle size of the Al powder and the Cu powder is 5-15 microns.

7. The preparation method of the Cu- (graphene/Al) multilevel layered composite material according to claim 5, wherein: the ball mill in the step one is realized by wet grinding of metal powder by adopting a stirring ball mill, absolute ethyl alcohol is selected as a process control medium, hard alloy balls are selected as a ball milling medium, and the ball-to-material ratio is 20: 1.

8. The preparation method of the Cu- (graphene/Al) multilevel layered composite material according to claim 5, wherein: and the concentration of the graphene oxide in the graphene oxide solution in the second step is 0.5-5 mg/mL.

9. The preparation method of the Cu- (graphene/Al) multilevel layered composite material according to claim 5, wherein: and fifthly, the temperature range of the spark plasma sintering is 450-550 ℃, and the pressure range is 50-200 MPa.

10. The preparation method of the Cu- (graphene/Al) multilevel layered composite material according to claim 5, wherein: and sixthly, the rolling direction is vertical to the thickness direction of the layered composite material, the rolling amount is controlled to be 2% each time, and the final thickness reduction of the composite material block is 40% through repeated heating and rolling.

Technical Field

The invention relates to the technical field of composite materials, in particular to a Cu- (graphene/Al) multilevel laminar composite material and a preparation method thereof.

Background

The Cu/Al layered composite material integrates physical, chemical and mechanical properties of Cu and Al, has the advantages of good electrical conductivity and high thermal conductivity of Cu, light weight and high plastic toughness of Al and the like, is a structural function integrated composite material with excellent comprehensive performance, and is widely applied to heat conduction and radiation and electric conduction devices in the aerospace field, such as light aerospace cables, heat control elements and the like. However, the continuous advance in the aerospace field promotes the rapid development of electric heating components in the directions of light weight, miniaturization and integration, and the strength, heat conduction, electric conduction and other properties of the traditional Cu/Al layered composite material cannot meet the comprehensive development requirements of electric heating components in a new generation aerospace craft on light weight, high strength, toughness and high conductivity.

The bottleneck of further improving the strength, heat conduction and electric conductivity of the Cu/Al layered composite material mainly comes from two aspects: (1) cu andthe mechanical and physical properties of Al are not matched. Pure Al has a strength of 1/2 for pure Cu only and a thermal and electrical conductivity of 3/5 for Cu only. The mismatching of the properties causes that Cu and Al can not effectively act synergistically in the service process of the Cu/Al layered composite material, and further improvement of the performance of the composite material is restricted; (2) al is easily generated at the interface of the Cu/Al laminated composite material₂Cu, AlCu and Al₄Cu₉And the like. A large number of researches show that the hard and brittle intermediate compound at the interface of the composite material can become a crack initiation source, and the resistivity and the thermal resistivity of the composite material are higher than those of Cu and Al, so that the composite material is unfavorable for the performance of the composite material. Therefore, on the basis that the Al layer keeps light weight and high plasticity and toughness, the strength, the heat conduction performance and the electric conduction performance of the Al layer are further improved, and the generation of brittle intermediate compounds between Cu/Al interfaces is effectively inhibited, so that the Cu/Al layered composite material is a scientific problem which is urgently needed to be solved.

In order to solve the problem of the property mismatching of the Cu layer and the Al layer in the Cu/Al layered composite material, the most effective method is to introduce a reinforcing phase into the Al layer by a compounding method to improve the strength, the heat conduction and the electric conductivity of the Al layer. One important principle to follow in choosing the reinforcement phase in the Al layer is: the introduction of the reinforcing phase can simultaneously improve the strength, heat conduction and electric conductivity of the Al layer, and cannot sacrifice the light weight and high ductility and toughness of the Al layer. Based on the principle, graphene can be introduced into an Al layer as an ideal reinforcing phase to comprehensively improve the mechanical property and the functional property of Al, and the graphene not only has high elastic modulus (-1 TPa), high tensile strength (-130 GPa) and high tensile plasticity (2)>10 percent), and the like, and has high conductivity (200,000 cm to 200,000 cm)²V^-1s^-1) High thermal conductivity (5000 Wm)^-1K^-1) And the like. Early researches on graphene/Al-based composite materials show that the composite materials still have obvious strength-plasticity/toughness inversion relationship contradictions, namely, the graphene improves the strength of the composite materials but reduces the tensile plasticity/toughness of the composite materials, and the development of the graphene/metal-based composite materials is restricted.

Disclosure of Invention

In order to solve the problems, the invention provides the Cu- (graphene/Al) multilevel layered composite material and the preparation method thereof, so that the prepared multilevel layered composite material has the characteristics of light weight, high strength and toughness, high heat conductivity, high electric conductivity and the like, and can be used for various light electric heating components for aerospace.

The invention is realized by the following technical scheme:

a Cu- (graphene/Al) multistage layered composite material macroscopically presents a Cu/Al layered structure, wherein a Cu layer microscopically presents a layered micro-nanocrystalline structure, and an Al layer microscopically presents a graphene/Al micro-nano laminated structure.

Furthermore, the thicknesses of the Cu layer and the Al layer on the macro surface of the composite material are respectively 2-4 mm.

Further, the scale of the layered micro-nanocrystalline structure of the Cu layer in the composite material is between 100 and 300 nm.

Further, the thickness of the lamellar Al in the graphene/Al micro-nano laminated structure of the composite material Al layer is 100-300 nm, the graphene is a single layer or few layers, and the thickness is less than 15 nm.

A preparation method of a Cu- (graphene/Al) multilevel layered composite material mainly comprises the following steps:

step one, preparing sheet metal powder: ball-milling Al powder and Cu powder by using a ball mill to prepare flaky Al powder and Cu powder with the thickness of 100-300 nm and the sheet diameter of 2-5 mu m;

step two, preparing a graphene dispersion liquid: adding graphene oxide into deionized water to obtain a graphene oxide solution, and then carrying out ultrasonic treatment to obtain a single-layer or few-layer graphene dispersion liquid;

step three, preparing graphene/aluminum flake composite powder: adding the flaky Al powder obtained in the step one and the graphene dispersion liquid obtained in the step two into absolute ethyl alcohol, stirring and mixing until the upper layer liquid of a beaker becomes colorless and transparent, then washing and filtering by using deionized water, vacuum drying to obtain graphene oxide/Al flaky composite powder, and then heating the graphene oxide/Al flaky composite powder under the hydrogen protective atmosphere to obtain graphene/Al flaky composite powder;

step four, layered self-assembly of the powder: uniformly paving the graphene/Al flaky composite powder obtained in the step three in a mold, sequentially stacking the graphene/Al flaky composite powder along the thickness direction, wherein the paving and stacking thickness is 19-21 mm, then uniformly paving the flaky Cu powder obtained in the step one above the graphene/Al flaky composite powder, and paving and stacking the flaky Cu powder above the graphene/Al flaky composite powder to obtain a Cu- (graphene/Al) layered powder blank;

step five, sintering preparation of the block composite material: performing discharge plasma sintering on the Cu- (graphene/Al) layered powder blank prepared in the fourth step to prepare a block Cu- (graphene/Al) multilevel layered composite material;

step six, hot rolling of the high-densification composite material: and (4) heating and rolling the block Cu- (graphene/Al) multistage layered composite material prepared in the fifth step to obtain the high-densification Cu- (graphene/Al) multistage layered composite material.

Further, the Al powder and the Cu powder selected in the first step are high-purity spherical Al powder and high-purity Cu powder respectively, the purities of the Al powder and the Cu powder are both 99.99%, and the average particle size of the Al powder and the Cu powder is 5-15 microns.

Further, the ball mill in the step one is realized by wet milling metal powder by adopting an agitating ball mill, absolute ethyl alcohol is selected as a process control medium, and hard alloy balls are selected as a ball milling medium, wherein the ball-to-material ratio is 20: 1.

Further, the concentration of the graphene oxide in the graphene oxide solution in the second step is 0.5-5 mg/mL.

Furthermore, the temperature range of the spark plasma sintering in the fifth step is 450-550 ℃, and the pressure range is 50-200 MPa.

Further, the rolling direction of the step six is perpendicular to the thickness direction of the laminated composite material, the rolling amount is controlled to be 2% each time, and the heating-rolling is repeated, so that the thickness reduction of the final composite material block is 40%.

The invention has the beneficial effects that:

(1) compared with the traditional Cu/Al composite material, the high-performance graphene is introduced into the Al layer, so that the problem that the mechanical and physical properties of Cu and Al are not matched can be effectively solved, and the generation of an intermediate compound at the interface of the Cu/Al composite material can be effectively inhibited, so that the strength, the thermal conductivity and the electric conductivity of the composite material can be improved;

(2) in the composite material prepared by the invention, Cu and Al are in macroscopic layers, and graphene is in micro-nano laminated distribution in an Al layer, so that the bionic multi-stage laminated structure distribution can improve the strength, heat conduction and electric conduction performance of the composite material and simultaneously keep the characteristics of light weight and high plastic toughness;

in conclusion, the invention provides a method for introducing graphene into the Al layer of the Cu/Al layered composite material based on the multi-scale layered configuration design by taking the regulation of the matching property of the mechanical properties and the physical properties of the Cu layer and the Al layer in the Cu/Al layered composite material and the inhibition of the intermediate compound at the Cu/Al interface as breakthrough points, the composite configuration prepared by the self-assembly of the sheet composite powder, the solid-phase hot-pressing sintering and the hot rolling technology presents a bionic multilevel laminated structure metal-based composite material, so that the composite material has higher strength, plasticity and functional characteristics, and is designed and prepared to present a Cu/Al laminated structure macroscopically, the Cu layer microscopically presents a layered micro-nanocrystalline structure, and the Al layer microscopically presents a multi-stage layered Cu- (graphene/Al) composite material with a graphene/Al micro-nano laminated structure, so that the composite material has excellent properties of light weight, high toughness, high conductivity and the like.

Drawings

FIG. 1 is a schematic flow diagram of a preparation process of the present invention;

FIG. 2 is a schematic microstructure diagram of the Cu- (graphene/Al) multilevel layered composite material prepared by the invention.

Detailed Description

The technical solutions in the embodiments of the present invention are clearly and completely described below.

Example 1:

a preparation method of a Cu- (graphene/Al) multilevel layered composite material mainly comprises the following steps:

step one, preparing sheet metal powder: ball-milling Al powder and Cu powder by using a ball mill to prepare flaky Al powder and Cu powder with the thickness of 300nm and the sheet diameter of 2-5 mu m; wherein the Al powder and the Cu powder in the raw materials are respectively high-purity spherical Al powder and high-purity Cu powder, the purity of the Al powder and the purity of the Cu powder are both 99.99%, and the average grain diameter of the Al powder and the Cu powder is 5-15 mu m; the ball mill is realized by wet grinding of metal powder by adopting an agitating ball mill, absolute ethyl alcohol is selected as a process control medium, hard alloy balls are selected as a ball milling medium, and the ball-material ratio is 20: 1.

Step two, preparing a graphene dispersion liquid: adding graphene oxide into deionized water to obtain a graphene oxide solution, wherein the concentration of the graphene oxide in the graphene oxide solution is 0.5-5 mg/mL, and then carrying out ultrasonic treatment to obtain a single-layer or few-layer graphene dispersion liquid;

step three, preparing graphene/aluminum flake composite powder by using an electrostatic adsorption method: adding the flaky Al powder obtained in the step one and the graphene dispersion liquid obtained in the step two into absolute ethyl alcohol, stirring and mixing until the upper layer liquid of a beaker becomes colorless and transparent, then washing and filtering by using deionized water, and drying in vacuum to obtain graphene oxide/Al flaky composite powder, and then heating the graphene oxide/Al flaky composite powder under the hydrogen protective atmosphere to eliminate the defects of oxygen-containing functional groups and the like on the surface of graphene oxide, so as to obtain graphene/Al flaky composite powder with the thickness of 300 nm;

step four, layered self-assembly of the powder: uniformly paving the graphene/Al flaky composite powder obtained in the step three in a mold, sequentially stacking the graphene/Al flaky composite powder along the thickness direction, wherein the paving and stacking thickness is 20mm, then uniformly paving the flaky Cu powder obtained in the step one above the graphene/Al flaky composite powder, and paving and stacking the flaky Cu powder above the graphene/Al flaky composite powder to obtain a Cu- (graphene/Al) layered powder blank;

step five, sintering preparation of the block composite material: performing discharge plasma sintering on the Cu- (graphene/Al) layered powder blank prepared in the fourth step to prepare a block Cu- (graphene/Al) multistage layered composite material, wherein the sintering temperature is 500 ℃, and the pressure is 100 MPa;

step six, hot rolling of the high-densification composite material: heating and rolling the block Cu- (graphene/Al) multistage layered composite material prepared in the fifth step to obtain the high-densification Cu- (graphene/Al) multistage layered composite material, wherein the rolling direction is vertical to the thickness direction of the layered composite material, the rolling amount is controlled to be 2% each time, and the final thickness reduction of the block of the composite material is 40% through repeated heating and rolling, so that the finally prepared Cu- (graphene/Al) multistage layered composite material macroscopically presents a Cu/Al layered structure, wherein the Cu layer microscopically presents a layered micro-nano crystal structure, and the Al layer microscopically presents a graphene/Al micro-nano laminated structure.

Example 2:

example 2 differs from example 1 in that:

in this example, the sintering temperature in the fifth step was 550 ℃ and the pressure was 150 MPa. Thereby obtaining the composite material with higher density.

Example 3

In this example, the thickness of the flake Cu powder and the flake graphene/Al composite powder in the first and third steps was 100 nm. Therefore, the prepared composite material has smaller grain size and further increased graphene content, and the performance of the composite material is further improved.

While there have been shown and described what are at present considered the fundamental principles of the invention, its essential features and advantages, it will be understood by those skilled in the art that the invention is not limited by the embodiments described above, which are merely illustrative of the principles of the invention, but various changes and modifications may be made therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents.