CN111593219A

CN111593219A - Nano ND-Cu/Al composite material and preparation method thereof

Info

Publication number: CN111593219A
Application number: CN202010440683.8A
Authority: CN
Inventors: 汤宏群; 闫玮; 张凤林; 周嘉昶; 李倩; 康鹤译; 马铭辰; 阙凡超; 王永海; 欧兴成
Original assignee: Guangxi University
Current assignee: Guangxi University
Priority date: 2020-05-22
Filing date: 2020-05-22
Publication date: 2020-08-28

Abstract

The invention discloses a nanometer ND-Cu/Al composite material and a preparation method thereof, belonging to the technical field of aluminum-based alloy materials. The interface bonding of the nano diamond particles and the Al matrix is obviously enhanced by using the ND-Cu composite, and the product aluminum matrix composite material ND-Cu/Al is obtained. The composite material ND-Cu/Al has excellent comprehensive performances of wear resistance, compression resistance and the like, and has good application prospect.

Description

Nano ND-Cu/Al composite material and preparation method thereof

Technical Field

The invention belongs to the technical field of aluminum-based alloy materials, and particularly relates to a nano ND-Cu/Al composite material and a preparation method thereof.

Background

With the progress of the times, the single metal material is difficult to meet the requirements of practical application, so that the metal matrix composite material with higher comprehensive performance is produced and developed rapidly. With the improvement of light weight, the application of novel light weight materials in the automobile and aerospace industries is extremely important. The aluminum-based composite material is a novel composite material formed by combining an aluminum alloy and a reinforcing phase material through a special preparation process, has excellent physical properties and mechanical properties such as small density, high specific strength and modulus, high toughness and impact resistance, low thermal expansion coefficient, good wear resistance and dimensional stability and the like, and is widely applied to high-end fields such as electronics, automobiles, high-speed rails, aerospace, ships, military industry and the like.

The aluminum-based composite materials may be classified into particle-reinforced aluminum-based composite materials (PAMCs), whisker-reinforced aluminum-based composite materials (SFAMCs), and fiber-reinforced aluminum-based composite materials (CFAMCs) according to the kind of the reinforcing phase. Compared with the fiber and whisker reinforced aluminum matrix composite, the particle reinforced aluminum matrix composite has the advantages of various and simple preparation processes, uniform microstructure, stable performance and low cost, can be subjected to secondary processing such as rolling, extrusion forging and the like and large-scale industrial application, and becomes one of new materials with the greatest development prospect and realization of large-scale production.

Diamond is the highest hardness substance known at present, and the hardness is about 90 GPa; the diamond structure is stable, is also the most wear-resistant material and is more than ten times wear-resistant than the ceramic material; so that the diamond is an ideal reinforcing phase material for preparing the aluminum matrix composite. Nanodiamond (ND) combines the dual properties of nanomaterials and diamond. The published literature reports that the influence of the aluminum additive on the thermal property of the titanium-plated diamond-copper composite material utilizes micron-sized diamond to improve the thermal conductivity of the material.

At present, most of domestic and foreign research workers concentrate on the micron diamond reinforced aluminum matrix composite, and reports on the control of the surface modification effect of the nano diamond and the reinforced aluminum matrix composite are few. This is because the characteristic small size effect and surface and interface effect of the nano-scale diamond make the nano-diamond very easy to aggregate, and the severe agglomeration of the nano-diamond and the existence of more amorphous carbon structures on the surface will affect their performance; and the nano diamond and Al base have poor wettability, the wetting angle is 130 degrees, and the nano diamond and the Al base are hardly wetted, so that the interface bonding property of the nano diamond and the Al base is poor.

The Chinese patent application with publication number CN106191540A discloses a nano-diamond silicon composite reinforced aluminum magnesium alloy for automobile electronic packaging and a preparation method thereof, and discloses raw materials of magnesium, copper, titanium, nano-diamond-silica sol, a pore-forming agent, ethanol and aluminum, wherein the nano-diamond-silica sol with the content of 50-60% is used, the nano-material has large dosage and high cost, and the material strength is reduced.

Therefore, there is a need to develop a material capable of solving the problems that the depolymerization and the wettability of the nanodiamond must face in the development and application of the material.

Disclosure of Invention

In order to solve the technical problems, the invention provides a nano ND-Cu/Al composite material and a preparation method thereof, and the obtained ND-Cu/Al composite material has excellent comprehensive performances such as wear resistance, compression resistance and the like and has good application prospect.

The following scheme is provided for achieving the purpose:

a preparation method of a nanometer ND-Cu/Al composite material comprises the following steps:

(1) putting the nano-diamond into king water, carrying out ultrasonic oscillation treatment for 1.5-2 h under the water bath condition, washing with water until the solution is neutral after the treatment is finished, and putting the obtained precipitate into a drying oven for drying to obtain pretreated nano-diamond for later use;

(2) weighing copper salt powder, preparing a copper salt aqueous solution with the concentration of 0.008-0.01 mol/L, adding pretreated nano diamond into the copper salt aqueous solution, adding a dispersing agent, and preparing a suspension by ultrasonic dispersion;

(3) adding a reducing agent into the suspension, heating in a water bath, and uniformly stirring, wherein the reaction time is 25-30 min; after the reaction is stopped, the reaction product is naturally cooled and then centrifugally separated, and the obtained product is used for later use;

(4) washing the compound with water until the solution is neutral, and then putting the compound into a vacuum drying oven for drying to obtain an ND-Cu mixture for later use;

(5) mixing the ND-Cu mixture and Al powder for 5 hours by mechanical ball milling to obtain uniform mixed powder;

(6) and pouring the mixed powder into a tungsten steel die for cold press molding, and finally obtaining the ND-Cu/Al composite material through vacuum hot press sintering.

Further, in the steps (1) and (3), the temperature of the water bath is 45-55 ℃.

Further, in the steps (1) and (4), the drying temperature is 40-47 ℃.

Further, in the step (2), the copper salt is CuCl₂、CuSO₄、Cu(NO₃)₂Either one of them; the dosage of the pretreated nano diamond is 15-20% of the mass fraction of the copper salt.

Further, in the step (2), the dispersant is any one of sodium dodecyl benzene sulfonate, sodium hexametaphosphate and polyvinyl alcohol, and the dosage of the dispersant is 4-5% of the mass fraction of the copper salt.

Further, in the step (3), the reducing agent is any one of hydrazine hydrate, hydroxylamine, potassium permanganate and hydrogen peroxide, and the dosage of the reducing agent is 2-3% of the volume of the copper salt.

Further, in the step (5), the amount of the ND-Cu mixture added is 1 to 7 vol.% of the Al powder.

Preferably, the ND-Cu mixture is added in an amount of 5 vol.% of the Al powder.

Further, in the step (6), the cold-press molding pressure is 130-150 MPa, and the pressure is maintained for 30-60 s.

Further, in the step (6), the hot-pressing sintering pressure is 35-40 MPa.

The invention provides a nano ND-Cu/Al composite material obtained by the preparation method, wherein the nano ND-Cu/Al composite material has the relative density of 90.22-96.03%, the microhardness of 47.4-104.8 HV, the yield strength of 96.53-191.72 MPa, the compressive strength of 218.89-349.99 MPa, the elongation of 5.95-19.32%, and the wear resistance of 62.5-67.1 g under the roughness of 1000#^-1。

The raw materials used in the invention are as follows: the particle size of the ash powder of the nano diamond is 10nm, and the surface appearance is spherical or quasi-spherical; the density is 3.05-3.3g/cm³The content of the nano diamond reaches more than 95 percent. Compared with the diamond with macroscopic size, the nano-diamond has small grain diameter and large specific surface which is about 278-²The surface activity is high, the number of carbon atoms on the surface is large, and atoms such as H, O, N are easily adsorbed to form groups such as-OH, -C ═ O, -COOH and CN.

The principle of the invention is as follows:

1. the invention adopts the nano diamond particles treated by strong acid to prepare the ND-Cu compound, and the nano diamond treated by strong acid removes a large amount of amorphous carbon and graphite phases on the surface of the nano diamond, thereby purifying the nano diamond particles to a great extent. Reduction of CuCl by hydrazine hydrate₂Salt solution, prepared reduction product attached to nano diamond particles with special properties to form nuclei and grow. The redox reaction occurring in solution is of the formula:

2Cu²⁺+H₂N·NH₂＝2Cu+N₂+4H⁺；

2. the nano-diamond as the nucleation and growing crystal nucleus of Cu can be explained by the relationship of uniform nucleation and non-uniform nucleation or heterogeneous nucleation, and the relationship between Gibbs free energy required to be increased by the uniform nucleation and the non-uniform nucleation can be expressed by the following formula:

in the formula (I), the compound is shown in the specification,

increased gibbs free energy required for heterogeneous nucleation;

increased gibbs free energy for uniform nucleation; theta is the contact angle of solid and liquid phases, and is generally more than 0 DEG and less than 180 DEG, i.e.

The Gibbs free energy required to be increased by the heterogeneous nucleation is much smaller than that required by the homogeneous nucleation, namely, compared with the homogeneous nucleation, copper ions are easy to nucleate and grow on the surface of the heterogeneous nucleation crystal nucleus of the nano diamond. According to the phase boundary energy theory, the lower the phase boundary energy, the easier the nucleation, i.e., the closer the lattice constant and structure are, the easier the lowest interfacial energy is reached, enhancing the ability of non-uniform nucleation. Copper and diamond are all face-centered cubic structures, the lattice constants of the copper and diamond are very close to each other and are respectively 0.361nm and 0.357nm, and the smaller the nucleation power is, the easier the nucleation is, so that copper particles can be attached to the nucleation of the nano diamond particles.

The invention has the following beneficial effects:

1. the nano-diamond can effectively remove amorphous carbon and graphite phase impurities on the surface of the nano-diamond by strong acid treatment, reduce hydroxyl O-H groups on the surface of the nano-diamond, reduce the number of dangling bonds of carbon atoms more obviously and obviously reduce the content of functional groups on the surface.

2. The invention utilizes nanodiamondND nanometer characteristic, using it as heterogeneous nucleation crystal nucleus, and adopting liquid phase reduction method to separate copper from CuCl₂Reducing the nanometer metal oxide in the solution, adhering to ND particles to form nuclei and grow up, and preparing the nanometer ND-Cu compound.

3. The ND-Cu compound prepared by vacuum hot-pressing sintering is used as the dispersed phase reinforced aluminum-based composite material, and the grain boundary migration and the growth of matrix grains are hindered in the sintering process. The volume fraction of ND is increased, the size of matrix grains is reduced and then increased, ND particles are uniformly distributed at the crystal boundary without obvious segregation phenomenon, and the defects are few; the finally prepared reinforced ND-Cu/Al composite material has obvious dispersion strengthening effect, and the introduced copper element forms solid solution strengthening phase Al at the crystal boundary along with the increase of the content₂And Cu remarkably enhances the interface bonding of the nano diamond particles and the Al matrix, and the obtained final material has clear crystal boundary, uniform size and excellent comprehensive performance.

4. The nano ND-Cu/Al composite material obtained by the invention has the relative density of 90.22-96.03%, the microhardness of 47.4-104.8 HV, the yield strength of 96.53-191.72 MPa, the compressive strength of 218.89-349.99 MPa, the elongation of 5.95-19.32%, and the wear resistance of 62.5-67.1 g under the roughness of 1000#^-1. Is an aluminum-based alloy material with good wear resistance and has good application prospect.

Drawings

Fig. 1 is an XRD pattern of the ND-Cu composite of example 1 of the present invention.

FIG. 2 is an SEM image of an ND-Cu composite of example 1 of the present invention.

FIG. 3 is a distribution diagram of the element C analyzed by EDS of the ND-Cu composite of example 1 of the present invention.

Fig. 4 is a distribution diagram of Cu element by EDS analysis of the ND-Cu composite of example 1 of the present invention.

FIG. 5 is a bar graph of the effect of different compositions ND on composite hardness.

Fig. 6 is a stress-strain curve for pure Al and each composite.

Fig. 7 is a wear profile of 1 vol.% ND at 1000 #.

Fig. 8 is a wear profile of 5 vol.% ND at 1000 #.

Fig. 9 is a wear profile of 5 vol.% ND at 600 #.

Fig. 10 is a metallographic structure chart of 1 vol.% ND.

Fig. 11 is a metallographic structure chart of 3 vol.% ND.

Fig. 12 is a metallographic structure chart of 5 vol.% ND.

Fig. 13 is a metallographic structure chart of 7 vol.% ND.

Fig. 14 is an EDS analysis chart of the composite material of example 3.

FIG. 15 is a distribution diagram of the composite material of example 3 analyzed for Al element by EDS.

Fig. 16 is a distribution diagram of the composite of example 3 analyzed for C element by EDS.

FIG. 17 is a distribution diagram of the composite material of example 3 analyzed for Cu element by EDS.

FIG. 18 EDS spectrum position map (500nm) of example 3 composite.

FIG. 19 EDS spectrum position plot (100nm) of example 3 composite.

Detailed Description

The present invention is further illustrated by the following examples in order that the advantages and features of the present invention may be more readily understood, but the scope of the invention is not limited to these examples.

EXAMPLE 1 preparation of ND-Cu mixture

The method comprises the following steps:

(1) putting the nano-diamond into king water, carrying out ultrasonic oscillation treatment for 1.5h at the water bath temperature of 45 ℃, carrying out ultrasonic cleaning for three times by using distilled water after the treatment is finished until the solution is neutral, putting the obtained precipitate into a drying oven for drying at the drying temperature of 58 ℃ to obtain the pretreated nano-diamond for later use;

(2) weighing CuCl₂Powder, CuCl with the concentration of 0.008mol/L is prepared₂Aqueous solution, and then the CuCl₂Adding pretreated nano diamond into the aqueous solution, adding dispersant sodium dodecyl benzene sulfonate, and preparing a suspension by ultrasonic dispersion; the dosage of the pretreated nano diamond is chlorine15% of the mass fraction of the cupric salt; the using amount of the dispersing agent is 4% of the mass fraction of the cupric chloride;

(3) adding hydrazine hydrate into the suspension, heating water in a water bath at 45 ℃ and uniformly stirring, wherein the reaction time is 25 min; after the reaction is stopped, the mixture is naturally cooled and then centrifugally separated, and the obtained solid is ready for use;

(4) and repeatedly washing the solid with deionized water until the solution is neutral, and then drying the solid in a vacuum drying oven for 24 hours at the drying temperature of 40 ℃ to obtain an ND-Cu mixture for later use.

The ND-Cu mixture obtained in example 1 was subjected to the following phase analysis:

1. the ND-Cu mixture obtained in example 1 was analyzed by an X-ray diffractometer manufactured by Japan science corporation as model No. RigakuD/MAX 2500V. The Cu Kalpha target is adopted during testing, the X-ray wavelength is 0.154056nm, the voltage used for testing is 40kV, the scanning speed is 8 DEG/min, and the scanning angle is 20-90 deg. The XRD pattern is shown in figure 1.

2. Microstructure morphology, compression fracture and wear surface are observed by using a Hitachi S-3400N type scanning electron microscope. The SEM spectrum is shown in FIG. 2.

3. The phases of the tissue and the distribution of the elements were analyzed with an EDS spectrometer. The EDS spectrum is shown in figure 3.

FIG. 1 is an XRD plot of ND-Cu composites. As can be seen from fig. 1, the 2 θ angles of the significant diffraction peaks were detected to be 44.64 ° and 82.41 °, which respectively correspond to the diffraction peaks of diamond, and the 2 θ angles of the significant diffraction peaks were 38.38 °, 44.64 °, 65.04 °, 78.17 ° and 82.41 °, which respectively correspond to the diffraction peaks of diamond, which are superimposed peaks of ND and Cu on the XRD curve due to the close proximity and almost coincidence of the characteristic peak positions of diamond with copper, and in addition, a diffraction peak of CuO due to the close proximity and almost coincidence of copper was detectedIs composed of The rice copper has high surface activity and is easy to be oxidized in the preparation process, so that a small amount of oxidation products are formed.

FIG. 2 is an SEM image of an ND-Cu composite. As can be seen from FIG. 2, the size of the ND-Cu composite is about 50nm, and the product particles are in spherical dense distribution, because the existence of ND in the reaction suspension is favorable for non-uniform nucleation of copper ions, the nucleation density is increased, and the prepared ND-Cu composite is in a nano-scale, so that the product particles have a certain agglomeration phenomenon.

Fig. 3 and 4 are EDS scans of the ND-Cu composite, and corresponding distributions of C and Cu elements in the EDS scans of fig. 3 and 4, respectively, show that ND is uniformly dispersed in Cu particles.

EXAMPLE 2 preparation of ND-Cu/Al composite

Mixing the ND-Cu mixture and Al powder obtained in the example 1 for 5 hours by mechanical ball milling to obtain uniform mixed powder; the amount of ND-Cu mixture added was 1 vol.% of Al powder; and pouring the mixed powder into a tungsten steel die with the diameter of 30mm for cold press molding, keeping the pressure at 150MPa for 1min, and finally performing vacuum hot-pressing sintering at the pressure of 40MPa to obtain the ND-Cu/Al composite material.

Example 3: the difference from example 2 is that: the amount of ND-Cu mixture added was 3 vol.% of the Al powder.

Example 4: the difference from example 2 is that: the amount of ND-Cu mixture added was 5 vol.% of the Al powder.

Example 5: the difference from example 2 is that: the amount of ND-Cu mixture added was 7 vol.% of the Al powder.

First, the following performance analyses were performed on each of the composite materials (hereinafter, referred to as 1 vol.% ND, 3 vol.% ND, 5 vol.% ND, and 7 vol.% ND) obtained in the above examples 2, 3, 4, and 5, respectively, and the raw material Al:

1. density: actual density ρ_{Fruit of Chinese wolfberry}Is measured by a full-automatic electronic densitometer with the model number of GH-128E.

Theoretical density ρ_{Theory of things}Calculated using the following formula: rho_{Theory of things}＝ρ_d×V_d+ρ_Al×V_Al

In the formula, ρ_{Theory of things}(g/cm³) Is the theoretical density, p, of the composite material_d(g/cm³) Is the density of the enhanced phase diamond, V_d(vol.%) is the volume fraction of reinforcing phase diamond, ρ_Al(g/cm³) Is the density, V, of the metal matrix aluminum_Al(vol.%) is the metal matrix aluminumVolume fraction of (a).

The relative density of the composite material can be calculated by the formula:

the results of the measurements and calculations are shown in table 1.

TABLE 1 Effect of different volume fractions of ND on the Experimental and relative Density of composites

Table 1 shows the data of theory, experiment and relative density of the composite material, the experimental composite material was formed by hot pressing sintering at 550 ℃ under 40MPa, hot pressing is a kind of reinforced sintering, the density of the hot pressed piece is increased by rearrangement and plastic flow of particles at the initial stage, and grain boundary sliding and volume diffusion become the leading factors of densification at the later stage of sintering. The relative density of the pure aluminum sample after sintering was 95.79%, except that the density of 3 vol.% ND was slightly increased, which was 96.03%. However, overall, the relative density of the composite material is in a descending trend along with the increase of the volume fraction of the ND, and the agglomeration phenomenon of the ND particles is more serious along with the increase of the volume fraction of the ND, so that the interface combination of the particles in the sintering process is influenced, and the defects such as gaps, looseness and the like are formed on the particles collectively.

2. Hardness: hardness testing was performed using a microvicker hardness tester model HVT-1000. The test loading was 2N and the dwell time was 10 s. Before testing, equipment needs to be calibrated, each sample is polished by 5000# abrasive paper, then the surface of each sample is subjected to dotting testing at 8 different positions, defects such as cracks and holes of the sample are avoided during microcosmic dotting, 8 hardness values are obtained, and finally the average value is obtained. The measurement results are shown in FIG. 5.

FIG. 5 is a bar graph of the effect of different compositions ND on composite hardness. As can be seen from fig. 5, the microhardness of the composite material gradually increased as the volume fraction of the nanodiamond increased. During sintering, the addition of ND particles and the applied pressure can hinder the growth of crystal grains, thereby achieving the effect of refining the crystal grains of the aluminum matrix. The smaller the crystal grain, the grain boundary per unit areaThe larger the fraction is, the more prominent the movement of dislocations is hindered, and grain boundary strengthening is achieved to increase hardness. When ND is 1 vol.%, microhardness is 47.4HV, which is 42% higher than the hardness of pure aluminum, 33.4 HV; when ND is 3 vol.%, microhardness is 87.5HV, microhardness is increased by 162% compared to that of pure aluminum; when ND is 5 vol.%, microhardness is 97.6HV, microhardness is increased by 192% compared to that of pure aluminum; when the volume fraction of the reinforcement phase ND was 7 vol.%, the microhardness reached a maximum of 104.8HV, an increase of 214% compared to pure aluminum. When the volume fraction ND is not less than 3%, the microhardness is remarkably increased when the ND-Cu composite is brought to a content such that Al is formed with the aluminum matrix₂And Cu improves the bonding property of the interface.

3. Compressive strength: compression testing was performed using a universal testing machine model Instron 880, which gave the compression curves and compression strengths shown in FIG. 6 and Table 2. The test specimen was 5X 10mm in size, and the surface of the test specimen was subjected to linear cutting with sandpaper to remove traces.

TABLE 2 mechanical Properties of ND-Cu/Al composites of different ND volume fractions

FIG. 6 is a stress-strain curve for pure Al and ND-Cu/Al composites. The compression test results are shown in table 2. The results show that by increasing the ND volume fraction, the yield strength and maximum compressive strength increase first and then decrease. The elongation decreases with increasing ND volume fraction. When the ND volume fraction was 5%, the yield strength and the maximum compression strength were maximized at 191.72MPa and 349.99MPa, respectively, which were improved by 201% and 80%, respectively, but the elongation was reduced to 9.80%, compared to the yield strength and the maximum compression strength of pure aluminum (63.71 MPa and 193.91MPa, respectively). The pure aluminum powder is hot-pressed and sintered under the same condition to prepare a sample, and according to the compression test result, the test sample with the compression rate of 30 percent is not broken, which shows that the pure aluminum material has good ductility. The surface wettability of ND is improved by preparing ND-Cu composite, and the interface bonding strength with Al base is improved due to the introduction of Cu element at the interfaceFormation of Al₂The Cu phase improves the interface bonding property, so that the yield strength and the compressive strength are greatly improved. When ND is 1 vol.% and 3 vol.%, the yield strength is increased by 52% and 131%, respectively, and better elongation is also achieved. As the ND volume fraction increased to 7%, the nano-diamond agglomeration was severe, so that the relative density of the composite decreased significantly and the interfacial bonding strength of the ND-Cu composite and Al matrix deteriorated.

4. Wear properties: and (3) carrying out abrasion performance test on the composite material by using an ML-100 abrasive abrasion tester. The size of the test sample is phi 4 multiplied by 25mm, and the rotating feed speed of the device is set to 4mm/r, so that the diameter of the test sample is consistent, and the test sample can be ensured not to contact with the same position of the abrasive paper. Before testing, a wear machine is used for polishing the surface of a test sample on 2000# silicon carbide abrasive paper with the loading force of 3N, and the surface of the test sample is polished to be flat, and the silicon carbide (the main component is SiC) abrasive paper with 600# and 1000# abrasive paper is subjected to the additional loading of 10N. The test specimens were cleaned with an ultrasonic cleaner before and after each test, then dried and weighed with an electronic balance model FA 2204. The wear resistance of the test materials at 1000# and 600# roughness is shown in table 3. The wear topography is shown in fig. 7-10.

TABLE 3 abrasion loss and abrasion resistance of the composites

As shown in Table 3, when the number of the opposite abrasive paper is 1000#, the abrasion loss of the ND-Cu/Al composite materials with different volume fractions is not large, the difference between adjacent materials is less than 1mg, the abrasion loss of the composite material with the ND volume fraction of 1% is 14.9mg at the minimum, the abrasion resistance is the best, and is improved by 5.3% compared with pure aluminum; the composite material with an ND volume fraction of 7% was 16mg, and the abrasion resistance was inferior to that of pure aluminum. When the number of the abrasive paper is 600#, the abrasion loss is obviously increased, the abrasion resistance of the composite material with the ND volume fraction of 1% and 3% is the best, the abrasion loss is respectively improved by 20.6% and 23.9% compared with pure aluminum, and the abrasion loss is respectively 27.1mg and 26.4 mg. When the roughness of the abrasive material is small, the composite material with 1 vol.% ND shows good wear resistance; at high roughness to abrasive materials, the 3 vol.% ND composite exhibited good wear resistance.

FIGS. 7-9 are wear topography plots of different volume fraction ND-Cu/Al composites under 10N load, 4mm/r rotation speed, and 1000# and 600# roughness, respectively. Fig. 7 is a wear profile of 1 vol.% ND at 1000 #. Fig. 8 is a wear profile of 5 vol.% ND at 1000 #. Fig. 9 is a wear profile of 5 vol.% ND at 600 #. Because the hardness of the aluminum matrix composite material is lower than that of the SiC spherical abrasive grains on the sand paper, a plurality of grinding marks are formed on the surface of the matrix, and the abrasive grains are abraded on the abraded surface. When the abrasive paper is 1000#, the friction surface with ND volume fraction of 5% is deeper than the grooves of the friction surface with ND volume fraction of 1%, and the friction surface with ND volume fraction of 1% has a plurality of uniformly distributed fine hard particles, so that the formation of scratches on the friction surface can be reduced. When the abrasive paper is 600#, the abrasive surface roughness is increased, and the composite material containing 5 vol.% of ND forms deeper scratches and obvious material falling traces on the friction surface due to the agglomeration of the nano-diamond, so that serious abrasive wear is generated, and the abrasive resistance of the composite material is much poorer.

Secondly, the following microstructural characterization was performed on each of the composite materials obtained in the above examples 2, 3, 4 and 5 (hereinafter, referred to as 1 vol.% ND, 3 vol.% ND, 5 vol.% ND and 7 vol.% ND respectively):

1. the warp-cut samples were first washed with an ultrasonic cleaner to remove the linear cutting oil stain, then wet-milled with sandpaper having a particle size of 1000#, 2000#, 3000# and 5000# respectively, and then polished on a metallographic sample polisher. The Kahler reagent component (2.5 vol.% HNO) of the etching solution is prepared in advance₃、1.5vol.％HCl、1vol.％HF、95vol.％H₂O). And (3) washing the polished sample with water and absolute ethyl alcohol, then drying the sample with a blower, corroding for 20s, and observing the metallographic structure of the ND/Al composite material by adopting a 4XC-MS inverted metallographic microscope. The observed topography is shown in fig. 10-13.

Fig. 10 is a metallographic structure chart of 1 vol.% ND. Fig. 11 is a metallographic structure chart of 3 vol.% ND. Fig. 12 is a metallographic structure chart of 5 vol.% ND. Fig. 13 is a metallographic structure chart of 7 vol.% ND. As can be seen, the grain boundaries of the composite material are clear and uniform. The ND particles in fig. 10, 11, 12 are uniformly distributed without significant segregation and have fewer defects. However, as the volume fraction ND increases, agglomeration becomes more pronounced, which can affect particle interface bonding during sintering. When ND was 7 vol.% (fig. 13), a significant increase in the number of holes was observed, resulting in a significant decrease in the relative density of the composite, which also adversely affected the overall performance of the composite. This is because the increased ND content tends to agglomerate, and many weak spots and weak interfaces exist after sintering, so that voids are increased at the ND agglomerates, and cracks propagate in these regions. And the Al particles form plastic flow among the ND particles, so that the ND particles are easier to generate segregation, the continuity among the aggregates is cut off, and the performance of the material is reduced.

2. The composite material 3 vol.% ND of example 3 was subjected to surface scanning, the surface scanning is shown in fig. 14 to 17, the EDS energy spectrum position analysis is shown in fig. 18 and 19, and the elemental composition ratio at each position is shown in table 4.

Fig. 14 is an EDS surface scan analysis chart of the composite of example 3. FIGS. 15 to 17 are the elemental distributions of Al, C and Cu, respectively. As can be seen from the figure, the nano-diamond is embedded into Al particles through repeated crushing and impact in the mechanical ball milling process, and is uniformly distributed in the matrix after sintering, while the Cu element is more uniformly distributed and is diffused from the grain boundary to the inside of the crystal to form a solid solution or an intermediate phase with the Al base.

TABLE 4 composition ratio of points of energy spectrum analysis

The EDS spectrum positions are shown in fig. 18 and 19, and the atomic ratios at the respective positions are shown in table 4. When the ND — Cu composite content reaches a certain level, Cu element is concentrated at the grain boundary white-bright region (fig. 18, point 1), thereby forming a white-bright circular-like shape at the grain boundary. The atomic ratio of Al to Cu in the region is close to 2: 1, and Al in the result of XRD analysis₂Cu was consistent, indicating that the precipitated phase was Al₂And (3) Cu. The Al matrix at point 2 is also accompanied by small amounts of C and Cu elements. FIG. 19 is an enlarged view of a portion of FIG. 18, showing spherical particles (dots)3) Is a nanodiamond embedded in an Al matrix. The aggregation and segregation of the nano reinforcing phase particles at the grain boundary reduces the grain boundary energy and improves the stability of the grain boundary.

EXAMPLE 6 preparation of ND-Cu mixture

The method comprises the following steps:

(1) putting the nano-diamond into king water, carrying out ultrasonic oscillation treatment for 2h at the water bath temperature of 55 ℃, carrying out ultrasonic cleaning for three times by using distilled water after the treatment is finished until the solution is neutral, putting the obtained precipitate into a drying box for drying at the drying temperature of 62 ℃ to obtain the pretreated nano-diamond for later use;

(2) weighing CuSO₄Powder, CuSO with the concentration of 0.01mol/L₄Aqueous solution, and then said CuSO₄Adding pretreated nano diamond into the aqueous solution, adding a dispersing agent sodium hexametaphosphate, and preparing a suspension by ultrasonic dispersion; the dosage of the pretreated nano diamond is 20 percent of the mass fraction of the copper salt; the using amount of the dispersing agent is 5% of the mass fraction of the copper salt;

(3) adding hydroxylamine into the suspension, heating water in a water bath at 55 ℃, and uniformly stirring for reaction for 30 min; after the reaction is stopped, the mixture is naturally cooled and then centrifugally separated, and the obtained solid is ready for use;

(4) and repeatedly washing the solid with deionized water until the solution is neutral, and then drying the solid in a vacuum drying oven for 24 hours at the drying temperature of 47 ℃ to obtain an ND-Cu mixture for later use.

EXAMPLE 7 preparation of ND-Cu mixture

The method comprises the following steps:

(1) putting the nano-diamond into king water, carrying out ultrasonic oscillation treatment for 1.8h at the water bath temperature of 48 ℃, carrying out ultrasonic cleaning for three times by using distilled water after the treatment is finished until the solution is neutral, putting the obtained precipitate into a drying oven for drying at the drying temperature of 60 ℃ to obtain the pretreated nano-diamond for later use;

(2) weighing Cu (NO)₃)₂Powder prepared with Cu (NO) at a concentration of 0.009mol/L₃)₂Aqueous solution, and then Cu (NO) is added₃)₂Adding pretreated nano-diamond into the aqueous solution, adding dispersant polyvinyl alcohol, and preparing a suspension by ultrasonic dispersion; the dosage of the pretreated nano diamond is 18 percent of the mass fraction of the copper salt; the using amount of the dispersing agent is 4.5 percent of the mass fraction of the copper salt;

(3) adding potassium permanganate into the suspension, heating water in a water bath at 50 ℃, and uniformly stirring, wherein the reaction time is 27 min; after the reaction is stopped, the mixture is naturally cooled and then centrifugally separated, and the obtained solid is ready for use;

(4) and repeatedly washing the solid with deionized water until the solution is neutral, and then drying the solid in a vacuum drying oven for 24 hours at the drying temperature of 45 ℃ to obtain an ND-Cu mixture for later use.

EXAMPLE 8 preparation of ND-Cu mixture

The method comprises the following steps:

(2) weighing Cu Cl₂Powder, CuCl with the concentration of 0.009mol/L₂Aqueous solution, and then the CuCl₂Adding pretreated nano-diamond into the aqueous solution, adding dispersant polyvinyl alcohol, and preparing a suspension by ultrasonic dispersion; the dosage of the pretreated nano diamond is 18 percent of the mass fraction of the copper salt; the using amount of the dispersing agent is 4.5 percent of the mass fraction of the copper salt;

(3) adding hydrogen peroxide into the suspension, heating water in a water bath at 50 ℃ and uniformly stirring, wherein the reaction time is 27 min; after the reaction is stopped, the mixture is naturally cooled and then centrifugally separated, and the obtained solid is ready for use;

The above description is only a preferred embodiment of the present invention, and it should be noted that the above preferred embodiment should not be considered as limiting the present invention, and the protection scope of the present invention should be subject to the scope defined by the claims. It will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the spirit and scope of the invention, and these modifications and adaptations should be considered within the scope of the invention.

Claims

1. A preparation method of a nanometer ND-Cu/Al composite material is characterized by comprising the following steps:

2. The method for preparing the nano ND-Cu/Al composite material as claimed in claim 1, wherein the water bath temperature in steps (1) and (3) is 45-55 ℃.

3. The method for preparing nano ND-Cu/Al composite material according to claim 1, wherein in the steps (1) and (4), the drying temperature is 40-47 ℃.

4. The method for preparing nano ND-Cu/Al composite material as claimed in claim 1, wherein in the step (2), the copper salt is CuCl₂、CuSO₄、Cu(NO₃)₂Either one of them; the dosage of the pretreated nano diamond is 15-20% of the mass fraction of the copper salt.

5. The method for preparing the nano ND-Cu/Al composite material as claimed in claim 1, wherein in the step (2), the dispersant is any one of sodium dodecyl benzene sulfonate, sodium hexametaphosphate and polyvinyl alcohol, and the amount of the dispersant is 4-5% by mass of the copper salt.

6. The preparation method of the nano ND-Cu/Al composite material as claimed in claim 1, wherein in the step (3), the reducing agent is any one of hydrazine hydrate, hydroxylamine, potassium permanganate and hydrogen peroxide, and the amount of the reducing agent is 2-3% of the volume of the copper salt.

7. The method for preparing nano ND-Cu/Al composite material according to claim 1, wherein in the step (5), the ND-Cu mixture is added in an amount of 1-7 vol.% based on the Al powder.

8. The method for preparing the nano ND-Cu/Al composite material according to claim 1, wherein in the step (6), the cold press molding pressure is 130-150 MPa, and the pressure is maintained for 30-60 s.

9. The method for preparing the nano ND-Cu/Al composite material as claimed in claim 1, wherein in the step (6), the hot-pressing sintering pressure is 35-40 MPa.

10. A nano ND-Cu/Al composite material obtained by the preparation method according to any one of claims 1 to 8, wherein the nano ND-Cu/Al composite materialThe relative density of the material is 90.22-96.03%, the microhardness is 47.4-104.8 HV, the yield strength is 96.53-191.72 MPa, the compressive strength is 218.89-349.99 MPa, the elongation is 5.95-19.32%, and the wear resistance is 62.5-67.1 g under the condition that the roughness is 1000#^-1。