Preparation method of high-purity monodisperse spherical nano-copper powder, nano-copper powder and application of nano-copper powder

Abstract

The invention discloses a preparation method of high-purity monodisperse spherical nano-copper powder, nano-copper powder and application of the nano-copper powder. The preparation method comprises the following steps: mixing copper sulfate, aliphatic diamine of which the complexing stability constant logK is 9.0-11.0 and polyvinylpyrrolidone of which the molecular weight is 5000-50000 Da in deionized water to form a uniform dispersion liquid; after heating, slowly dropwise adding 80% hydrazine hydrate at a specific stirring rate for reduction reaction; and finally, separating, purifying and drying to obtain the nano copper powder. Through the synergistic effect of the specific complexing agent and the dispersing agent, under the high concentration of 0.5-0.7 mol / L, the copper ion reduction rate and crystal nucleus growth are precisely regulated and controlled, and the high-quality spherical nano-copper powder with the purity larger than or equal to 99.5%, the sphericity larger than or equal to 0.9 and the particle size distribution span value Span smaller than or equal to 0.5 is successfully prepared. The preparation process is simple, mild in condition and easy to industrially amplify. The obtained nano copper powder is regular in morphology and excellent in dispersity, and has wide application prospects in the fields of conductive slurry, conductive ink, catalysts, heat-conducting and wear-resistant composite materials and the like.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterial preparation technology, specifically relating to a method for preparing high-purity monodisperse spherical copper nanopowder, the copper nanopowder and its applications. Background Technology

[0002] As an important basic functional material, nano-copper powder is increasingly valued in fields such as electronics, advanced manufacturing, and energy catalysis due to its excellent electrical conductivity, thermal conductivity, and catalytic properties. However, with the rapid development of downstream high-end application technologies, the market has placed almost stringent requirements on the comprehensive performance of nano-copper powder. Especially in fields where the consistency of final product performance, process stability, and reliability are extremely important, the sphericity and monodispersity of nano-copper powder (i.e., extremely narrow particle size distribution) have become key factors determining its applicability. In the field of high-end electronic pastes and conductive inks, nano-copper powder is required to have extremely high sphericity and a very narrow particle size distribution when used for printing electrodes for electronic, flexible circuits, and microelectronic devices. Spherical particles ensure excellent rheological properties and printability of the paste, enabling uniform printing of fine lines; while monodisperse particle size ensures uniform particle shrinkage during subsequent sintering, forming a dense, highly conductive, and mechanically strong conductive film, avoiding circuit cracking or performance degradation due to uneven local shrinkage. Any irregular morphology or wide particle size distribution will lead to decreased paste stability, uneven printed lines, and porosity in the sintered body, failing to meet the requirements of high-end electronic manufacturing.

[0003] In the fields of powder metallurgy and 3D printing (additive manufacturing), spherical, monodisperse powders are a prerequisite for achieving high-precision, high-density printed parts. Spherical powders have excellent flowability, ensuring uniform powder distribution; their narrow particle size distribution guarantees consistent energy absorption and melting behavior during printing, resulting in products with uniform performance. Irregularly shaped or widely distributed powders lead to uneven powder distribution and increased printing defects, severely impacting yield and performance.

[0004] In the field of high-performance thermal conductivity and catalysis, spherical and uniformly sized nano-copper powder can achieve the densest packing and uniform distribution in composite materials or catalyst supports, thereby forming a highly efficient thermal conductivity / reaction network and maximizing its functional performance.

[0005] However, existing technologies for preparing nano-copper powder generally cannot simultaneously meet the requirements of high sphericity and extremely narrow particle size distribution, especially in the high-concentration reaction systems required for industrial production, where this problem is particularly prominent. For example, Chinese patent application CN102205422A uses a hydrothermal method, and its product has an irregular morphology (such as elongated strips or irregular spheres). Judging from the attached drawings, its particle size distribution ranges from 50 to 200 nm, which cannot meet the stringent monodispersity requirements of the aforementioned high-end applications. While Chinese patent application CN103769598A focuses on process stability, its technical solution also produces nano-copper powder with a wide particle size distribution range (50-200 nm), and it does not specify requirements or provide technical guidance regarding sphericity and particle size distribution concentration. Chinese patent application CN116727658A's core technology lies in actively constructing a bimodal composite structure, solidifying the wide distribution characteristic through process design, achieving a particle size distribution range of 50-500 nm.

[0006] In summary, existing technologies either fail to address the sphericity and monodispersity of nano-copper powder, or their inherent limitations (such as hydrothermal methods and bimodal distribution designs) prevent their products from meeting the demands of high-end applications. Most liquid-phase reduction methods, especially under high-concentration reaction conditions, struggle to balance industrial production efficiency with extremely narrow particle size distribution and high sphericity of the product.

[0007] Therefore, developing a simple method to stably prepare spherical copper nanopowder with high purity, high sphericity and extremely narrow particle size distribution (i.e., monodispersity) at high concentrations has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0008] The purpose of this invention is to develop a simple method for the stable preparation of high-purity, high-sphericity, and extremely narrow particle size distribution (i.e., monodispersity) spherical copper nanopowder at high concentrations.

[0009] In a first aspect, the present invention provides a method for preparing high-purity monodisperse spherical copper nanopowder, the specific technical solution of which is as follows: A method for preparing high-purity monodisperse spherical copper nanopowder, the specific steps of which are as follows: Step 1: Add copper sulfate, aliphatic diamine, and polyvinylpyrrolidone to deionized water and stir at 300-500 rpm for 10-20 minutes to form a homogeneous dispersion; wherein the concentration of copper sulfate is 0.5-0.7 mol / L, and the concentration of aliphatic diamine is 1-1.4 mol / L; the aliphatic diamine is a compound that reacts with Cu... 2+ The compound having a complexation stability constant logK of 9.0 to 11.0; the polyvinylpyrrolidone having a molecular weight of 5000-50000 Da; Step 2: Heat the dispersion obtained in Step 1 to 50-70℃, and add 80% hydrazine hydrate dropwise at a stirring rate of 0.5-5 mL / s while stirring at 300-600 r / min. The molar ratio of hydrazine hydrate to copper sulfate is 1:(2-3). After the addition is complete, continue the reaction at 50-70℃ for 0.5-2 hours to obtain a suspension of nano-copper powder. Step 3: Separate, purify, and dry the nano-copper powder suspension obtained in Step 2 to obtain nano-copper powder; the nano-copper powder has a purity ≥99.5%, sphericity ≥0.9, and particle size distribution span ≤0.5, wherein the particle size distribution span = (D 90 -D 10 ) / D 50 .

[0010] In this invention, the complexation stability constant logK refers to the complexation stability constant of aliphatic diamine molecules and Cu under the conditions of a standard temperature of 25°C and a constant aqueous solution with an ionic strength of I = 0.1 mol / L (maintained by KNO3). 2+ Ions form a 1:1 complex ([Cu(L))) 2+ The commonly used logarithmic value of the stepwise stability constant of ).

[0011] Those skilled in the art can confirm or obtain the logK value of the aliphatic diamine compound in the following two ways: (1) Citing recognized authoritative data The logK value can be cited from recognized authoritative chemical data handbooks, databases, or peer-reviewed scientific literature in the field. For example, *Stability Constants of Metal-Ion Complexes* (edited by LG Sillén and AE Martell) and the critical stability constants database of the National Institute of Standards and Technology (NIST). For instance, according to the aforementioned authoritative sources, ethylenediamine and Cu... 2+ The logK value is 10.5, while the logK value of 1,3-diaminopropane is approximately 9.8.

[0012] (2) Experimental measurement methods For compounds not explicitly described in the literature, they can be experimentally determined using the standard pH potentiometric titration method in this field. The specific determination procedure is summarized below: Test environment: The test was conducted at a constant temperature of 25℃ and under an inert atmosphere (high-purity nitrogen) to eliminate interference from carbon dioxide and oxygen.

[0013] Solution preparation: Prepare a series of solutions with constant ionic strength (I = 0.1 mol / L KNO3) containing known and precise concentrations of Cu. 2+A mixed aqueous solution of ions and the aliphatic diamine to be tested.

[0014] Titration process: The above mixture is titrated with a precisely calibrated standard KOH solution (e.g., 0.1 mol / L), and the pH value of the solution is continuously and accurately recorded with the amount of titrant added using a high-precision pH meter.

[0015] Data processing: Using professional computer programs (such as Hyperquad, SUPERQUAD, etc.), nonlinear least squares fitting analysis is performed on the obtained complete titration curve (pH value vs. amount of alkali added) to calculate the accurate successive stability constant, i.e., the required logK value.

[0016] Furthermore, the aliphatic diamine is selected from any one of ethylenediamine, 1,3-diaminopropane, or 1,2-diaminopropane.

[0017] Furthermore, the concentration of aliphatic diamine in the dispersion is 1-1.4 mol / L; preferably 1.2 mol / L.

[0018] Furthermore, the polyvinylpyrrolidone is PVP K-30.

[0019] Furthermore, the concentration of polyvinylpyrrolidone in the dispersion is 0.5-2.0 g / L.

[0020] Furthermore, the conductivity of deionized water is ≤10μS / cm.

[0021] Furthermore, the reaction temperature in step two is 60°C; the stirring rate is 400-600 r / min; and the dropping rate of the hydrazine hydrate is 1-3 mL / s.

[0022] Secondly, the present invention provides a high-purity monodisperse spherical copper nanopowder, which is prepared by any of the methods described above; the copper nanopowder has a purity ≥99.5%, a sphericity ≥0.9, and a particle size distribution span ≤0.5, wherein the particle size distribution span = (D 90 -D 10 ) / D 50 .

[0023] Thirdly, the present invention provides a high-purity monodisperse spherical nano-copper powder for use in the preparation of conductive pastes, conductive inks, catalysts, thermally conductive composite materials, or wear-resistant composite materials.

[0024] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention successfully achieves precise control over the reduction rate of copper ions and crystal nucleus growth at industrial-grade reaction concentrations of 0.5-0.7 mol / L. This is achieved through the synergistic effect of aliphatic diamines with specific complexation stability constants (logK of 9.0-11.0) and PVP of a specific molecular weight, while simultaneously realizing high purity, high sphericity, and extremely narrow particle size distribution. This overcomes the technical challenge of uneven particle size and agglomeration caused by high-concentration reactions, significantly improving production efficiency. The entire reaction is carried out in an aqueous phase at normal pressure and medium to low temperatures (50-70℃), requiring no complex high-pressure equipment or special protective atmospheres. The process is simple, with low equipment requirements, and safe and controllable operation, making it highly suitable for large-scale industrial production.

[0025] 2. The nano-copper powder prepared by this invention has an extremely narrow particle size distribution (span ≤ 0.5), sphericity ≥ 0.9, purity ≥ 99.5%, and a regular and uniform morphology, achieving true "monodispersion." This effectively solves the problems of wide particle size distribution and poor batch stability of conventional nano-copper powder, and also gives it excellent flowability and filling density in fields such as electronic pastes and 3D printing, enabling the formation of dense, high-performance conductive films or structural components. The nanoscale and regular spherical morphology endow the powder with a larger specific surface area and higher surface activity, making it suitable for high-end applications such as catalysis and thermal conductivity. Attached Figure Description

[0026] Figure 1 This is a SEM image of the copper powder prepared in Example 1 of the present invention; Figure 2 This is a SEM image of the copper powder prepared in Example 2 of the present invention. Detailed Implementation

[0027] To enable those skilled in the art to better understand the technical solutions of this invention, the present application will be further described in detail below with reference to specific embodiments.

[0028] [Example 1] A method for preparing high-purity monodisperse spherical copper nanopowder, the specific steps of which are as follows: (1) Preparation of copper source solution Copper sulfate pentahydrate (CuSO4·5H2O) was dissolved in deionized water with a conductivity ≤10μS / cm and stirred until completely dissolved to prepare a clear copper sulfate aqueous solution with a concentration of 0.6 mol / L.

[0029] (2) Preparation of complexed dispersion Ethylenediamine (logK = 10.5) and polyvinylpyrrolidone (PVP K-30, molecular weight 40000 Da) were added sequentially to the copper sulfate solution obtained in step (1). The stirring rate of the system was controlled at 400 r / min, and stirring was continued for 15 minutes to form a uniform and stable dispersion. The amount of ethylenediamine added was 1.2 mol / L, and the amount of polyvinylpyrrolidone added was 1.0 g / L.

[0030] (3) To carry out a reduction reaction The complexed dispersion obtained in step (2) was transferred to a constant temperature water bath, heated to 60°C and kept at a constant temperature. Under stirring conditions of 500 r / min, an 80% hydrazine hydrate solution was slowly and uniformly added to the system at a rate of 2 mL / s using a constant pressure dropping funnel.

[0031] The molar ratio of the total amount of hydrazine hydrate added to copper sulfate was controlled to be 1:2.3.

[0032] After the addition was complete, the reaction was continued at the same temperature and with stirring for 1 hour. Throughout the reaction, the solution gradually changed from blue to dark brownish-red, eventually yielding a suspension of nano-copper powder.

[0033] (4) Post-processing and storage After the reaction was completed, the resulting nano-copper powder suspension was centrifuged at 8000 r / min for 15 minutes, and the bottom precipitate was collected.

[0034] First, wash the precipitate three times with deionized water, then wash it twice with anhydrous ethanol to thoroughly remove residual PVP and soluble impurities.

[0035] The washed nano-copper powder wet filter cake was redispersed in anhydrous ethanol to form a slurry, and then stored in a sealed container to prevent oxidation.

[0036] When dry powder is required, the above wet powder is dried for 8 hours under a vacuum of ≤-0.09 MPa and 40℃. After drying, it is cooled to room temperature in an oven and removed under nitrogen protection, then immediately sealed and stored.

[0037] The prepared nano-copper powder was characterized by inductively coupled plasma optical emission spectrometry (ICP-OES), which showed a copper powder purity of 99.72%. (Refer to...) Figure 1 D was measured through SEM image analysis. 10 For 60.5nm, D 50 For 68.8nm, D 90The particle size was 83.5 nm, with a span of 0.33 and an average sphericity of 0.94. The sphericity was obtained by analyzing scanning electron microscope (SEM) images and using image analysis software to calculate the ratio of the projected area of ​​the particle to the area of ​​a circle with equal perimeter (Circularity). At least 200 particles were counted.

[0038] [Example 2] The only difference between Example 2 and Example 1 is that ethylenediamine is replaced with an equal amount of 1,3-diaminopropane (logK ≈ 9.8).

[0039] The prepared nano-copper powder was characterized by inductively coupled plasma optical emission spectrometry (ICP-OES), which showed a copper powder purity of 99.63%. (Refer to...) Figure 2 D was measured through SEM image analysis. 10 For 61nm, D 50 For 71nm, D 90 The particle size was 88 nm, with a particle size distribution span of Span = 0.38 and an average sphericity of 0.91. The results show that high sphericity and narrow distribution of copper nanoparticles can still be prepared using 1,3-diaminopropane with a slightly lower logK, but the sphericity and Span are slightly inferior to those in Example 1. This proves that the morphology can be effectively controlled by the logK of aliphatic diamines in the range of 9.0-11.0, and the higher the logK in this range, the better the effect.

[0040] [Example 3] The only difference between Example 3 and Example 1 is that PVP K-15 (molecular weight of 8000 Da) is used instead of PVP K-30.

[0041] The prepared nano-copper powder was characterized by inductively coupled plasma optical emission spectrometry (ICP-OES), which showed a copper powder purity of 99.55%. SEM image analysis determined the D... 10 For 57nm, D 50 For 73nm, D 90 The particle size distribution is 92 nm, with a span of 0.48 and an average sphericity of 0.91. The results show that even when the PVP molecular weight is at the lower limit of the range, it still meets the requirement of Span ≤ 0.5.

[0042] [Example 4] The only difference between Example 4 and Example 1 is that the concentration of the prepared copper sulfate aqueous solution is 0.5 mol / L.

[0043] The prepared nano-copper powder was characterized by inductively coupled plasma optical emission spectrometry (ICP-OES), which showed a copper powder purity of 99.68%. SEM image analysis determined the D... 10 For 51nm, D 50 58nm, D 90 The particle size is 74 nm, with a particle size distribution span of Span = 0.40 and an average sphericity of 0.93.

[0044] [Example 5] The only difference between Example 5 and Example 1 is that the concentration of the prepared copper sulfate aqueous solution is 0.7 mol / L.

[0045] The prepared nano-copper powder was characterized by inductively coupled plasma optical emission spectrometry (ICP-OES), which showed a copper powder purity of 99.58%. SEM image analysis determined the D... 10 For 65nm, D 50 For 78nm, D 90 The particle size was 96 nm, with a span of 0.40 and an average sphericity of 0.92. The results show that industrial-grade high-concentration copper nanoparticles with good sphericity and narrow particle size distribution can still be produced.

[0046] [Compare with Example 1] The only difference between Comparative Example 1 and Example 1 is that ammonia with equimolar functional groups is used instead of ethylenediamine. Specifically, to ensure compatibility with Cu... 2+ The total number of coordinated amino functional groups is the same as in Example 1, and the following calculations and substitutions are performed: In Example 1, the amount of ethylenediamine (containing two amino groups) added was 1.2 mol / L, which, upon calculation, provided an effective amino functional group concentration of 2.4 mol / L. Therefore, the same concentration (2.4 mol / L) of amino functional groups was required in Control Example 1. Ammonia solution with a concentration of 30 wt% and a density of approximately 0.89 g / mL (containing one amino group per molecule) was used as a substitute, requiring approximately 136 g of this ammonia solution per L upon calculation.

[0047] Add ammonia water according to this calculation, and the remaining steps are exactly the same as in Example 1.

[0048] The prepared nano-copper powder was characterized by inductively coupled plasma optical emission spectrometry (ICP-OES), which showed a copper powder purity of 98.43%. SEM image analysis determined the D... 10 For 85nm, D 50 For 120nm, D 90The particle size was 247 nm, with a span of 1.35 and an average sphericity of 0.75. The results showed that using ammonia instead of ethylenediamine could not effectively control the Cu content. 2+ The reduction rate and crystal nucleus growth lead to uncontrolled morphology, increased irregular copper powder and agglomeration, and a wider particle size distribution.

[0049] [Compare with Example 2] The only difference between Comparative Example 2 and Example 1 is that copper chloride (CuCl2) is used instead of copper sulfate pentahydrate to prepare equimolar concentration solutions.

[0050] The prepared nano-copper powder was characterized by inductively coupled plasma optical emission spectrometry (ICP-OES), which showed a copper powder purity of 97.95%. SEM image analysis determined the D... 10 For 72nm, D 50 For 95nm, D 90 The particle size was 186 nm, with a span of 1.20 and an average sphericity of 0.70, exhibiting irregular polyhedral characteristics. The results showed an increase in irregular particles in the prepared copper powder, possibly due to chloride ion adsorption on the crystal faces leading to anisotropic growth and disrupting sphericity.

[0051] [Compare with Example 3] The only difference between Comparative Example 3 and Example 1 is that copper nitrate (Cu(NO3)2) was used instead of copper sulfate pentahydrate to prepare equimolar concentration solutions.

[0052] The prepared nano-copper powder was characterized by inductively coupled plasma optical emission spectrometry (ICP-OES), which showed a copper powder purity of 98.76%. SEM image analysis determined the D... 10 For 80nm, D 50 For 110nm, D 90 The particle size was 245 nm, with a span of 1.50 and an average sphericity of 0.72, indicating severe porosity and agglomeration. This may be because nitrate ions participate in side reactions during reduction, consuming reducing agents and locally altering the pH, leading to uncontrolled nucleation and growth.

[0053] [Compare with Example 4] The only difference between Comparative Example 4 and Example 1 is that PVP K-60 (molecular weight 400,000 Da) was used instead of PVP K-30.

[0054] The prepared nano-copper powder was characterized by inductively coupled plasma optical emission spectrometry (ICP-OES), which showed a copper powder purity of 99.65%. SEM image analysis determined the D... 10 For 64nm, D 50For 78nm, D 90 The particle size was 108 nm, with a span of 0.56 and an average sphericity of 0.92. Some particles were aggregated. The results showed that while selecting PVP with a larger molecular weight could ensure sphericity, it resulted in a wider copper powder particle size distribution.

[0055] [Compare with Example 5] The only difference between Comparative Example 5 and Example 1 is that polyvinyl alcohol (PVA, molecular weight 10000 Da) is used instead of polyvinylpyrrolidone (PVP).

[0056] The prepared nano-copper powder was characterized by inductively coupled plasma optical emission spectrometry (ICP-OES), which showed a copper powder purity of 99.05%. SEM image analysis determined the D... 10 For 105nm, D 50 For 150nm, D 90 The particle size was 375 nm, with a span of 1.80 and an average sphericity of 0.65, indicating severe particle agglomeration. The results showed that PVA was less effective than PVP in stabilizing copper crystal nuclei, leading to particle agglomeration and uneven growth during the reduction process.

[0057] [Compare with Example 6] The only difference between Comparative Example 6 and Example 1 is that PVP is not added when preparing the dispersion, and PVP and hydrazine hydrate are added to the reaction system simultaneously.

[0058] The prepared nano-copper powder was characterized by inductively coupled plasma optical emission spectrometry (ICP-OES), which showed a copper powder purity of 99.18%. SEM image analysis determined the D... 10 For 98nm, D 50 For 130nm, D 90 The particle size was 261 nm, with a span of 1.25 and an average sphericity of 0.68, forming hard agglomerates. When preparing the dispersion, no PVP was added. The lack of PVP protection in the initial stage of the reaction led to instantaneous nucleation and agglomeration, which could not be deagglomerated in the later stages, resulting in a wider copper powder particle size distribution.

[0059] [Compare with Example 7] The only difference between Comparative Example 7 and Example 1 is that the concentration of the prepared copper sulfate aqueous solution is 0.9 mol / L.

[0060] The prepared nano-copper powder was characterized by inductively coupled plasma optical emission spectrometry (ICP-OES), which showed a copper powder purity of 98.52%. SEM image analysis determined the D... 10 For 105nm, D 50 For 150nm, D90 The particle size is 353 nm, with a particle size distribution span of Span=1.65 and an average sphericity of 0.70, indicating the presence of large, irregularly sized particles.

[0061] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for preparing high-purity monodisperse spherical copper nanopowder, characterized in that, The specific steps are as follows: Step 1: Add copper sulfate, aliphatic diamine, and polyvinylpyrrolidone to deionized water and stir at 300-500 rpm for 10-20 minutes to form a homogeneous dispersion; wherein the concentration of copper sulfate is 0.5-0.7 mol / L, and the concentration of aliphatic diamine is 1-1.4 mol / L; the aliphatic diamine is a compound that reacts with Cu... 2+ The compound having a complexation stability constant logK of 9.0 to 11.0; the polyvinylpyrrolidone having a molecular weight of 5000-50000 Da; Step 2: Heat the dispersion obtained in Step 1 to 50-70℃, and add 80% hydrazine hydrate dropwise at a stirring rate of 0.5-5 mL / s while stirring at 300-600 r / min. The molar ratio of hydrazine hydrate to copper sulfate is 1:(2-3). After the addition is complete, continue the reaction at 50-70℃ for 0.5-2 hours to obtain a suspension of nano-copper powder. Step 3: Separate, purify, and dry the nano-copper powder suspension obtained in Step 2 to obtain nano-copper powder; the nano-copper powder has a purity ≥99.5%, sphericity ≥0.9, and particle size distribution span ≤0.5, wherein the particle size distribution span = (D 90 -D 10 ) / D 50 .

2. The method for preparing high-purity monodisperse spherical nano-copper powder according to claim 1, characterized in that: The aliphatic diamine is selected from any one of ethylenediamine, 1,3-diaminopropane, or 1,2-diaminopropane.

3. The method for preparing high-purity monodisperse spherical nano-copper powder according to claim 1, characterized in that: The polyvinylpyrrolidone is PVP K-30.

4. The method for preparing high-purity monodisperse spherical nano-copper powder according to claim 3, characterized in that: The concentration of polyvinylpyrrolidone in the dispersion is 0.5-2.0 g / L.

5. The method for preparing high-purity monodisperse spherical nano-copper powder according to any one of claims 1-4, characterized in that: The reaction temperature in step two is 60℃; the stirring rate is 400-600 r / min; and the dropping rate of hydrazine hydrate is 1-3 mL / s.

6. A high-purity monodisperse spherical copper nanopowder prepared by the method according to any one of claims 1-5, characterized in that: The nano-copper powder has a purity ≥99.5%, sphericity ≥0.9, and particle size distribution span ≤0.5, wherein the particle size distribution span = (D 90 -D 10 ) / D 50 .

7. The nano-copper powder according to claim 6, characterized in that: The D of the nano copper powder 50 It is 50-80nm.

8. The use of the high-purity monodisperse spherical nano-copper powder according to claim 6 or 7 in the preparation of conductive pastes, conductive inks, catalysts, thermally conductive composite materials or wear-resistant composite materials.

Images