WO2018169428A1

WO2018169428A1 - Method for producing copper matrix nanocomposite materials

Info

Publication number: WO2018169428A1
Application number: PCT/RU2017/000133
Authority: WO
Inventors: Виктор Владимирович РЯБЫХ
Original assignee: Общество с ограниченной ответственностью "Карбон тех"
Priority date: 2017-03-15
Filing date: 2017-03-15
Publication date: 2018-09-20

Abstract

The invention relates to technologies for the production of composite materials comprising copper or copper alloys such as brass or bronze as a matrix, and carbon nanotubes as a filler. The invention can be used in various industries, preferably in the chemical and metal industries. A method for producing a copper matrix composite material is provided, the method comprising modifying carbon nanotubes with metal and compressing them into solid blocks; in accordance with the method nanotubes are modified with a metal selected from copper, and/or lead, and/or tin, and/or zinc, and/or aluminium, and/or silver, and then the modified carbon nanotubes are mixed with a copper powder having a fraction size of 3 to 10 µm, the resulting mixture is subjected to mechanical activation, the mechanically activated mixture is compressed by pressing into solid blocks, which then are heated in the absence of oxygen to at least melting temperature, melted and then cooled. The invention solves the problem of developing a method for producing a copper matrix composite material with excellent physical and mechanical properties, which material can have a different concentration of carbon nanotubes and can be used as a ready-to-use nanocomposite material for further processing, inter alia, for machining, or as an alloying composition in the production of copper alloys.

Description

METHOD FOR PRODUCING NANOCOMPOSITE MATERIALS

BASED ON COPPER MATRIX

The invention relates to technologies for producing composite materials containing copper or its alloys, such as brass or bronze, as a matrix, and carbon nanotubes as a filler. It can be used in various industries, mainly in the chemical and metallurgical.

Currently, composite materials containing carbon nanotubes as a filler are widely used, which is explained by a significant improvement in the properties of the materials to which these nanotubes are added. In particular, a copper-based nanocomposite material containing carbon nanotubes has higher strength, electrical conductivity, and other physical characteristics in comparison with copper.

Various methods are known for producing copper-based nanocomposite materials.

For example, composite materials based on a copper matrix are known, reinforced by the addition of 0.2, 5 and 10 vol. % single-walled carbon nanotubes and 5 and 10 vol. % multilayer carbon nanotubes [Shukla, A. K. Nayan, Niraj Murty, SVSN Sharma, SC Chandran, Prathap Bakshi, Srinivasa R. George, Koshy M. Processing of copper-carbon nanotube composites by vacuum hot pressing technique- MATERIALS SCIENCE AND ENGINEERING A - STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING, p. 365-371, DOI: 10.1016 / j.msea.2012.09.09.080]. They are obtained by high-energy grinding of pure copper powder with carbon nanotubes, followed by compaction by hot pressing in vacuum. By hot pressing, a sintered composite material based on copper is obtained, which shows a significant improvement in strength with increasing carbon nanotube content. The disadvantage of this material is the uneven distribution of carbon nanotubes in the longitudinal and transverse directions.

A known method of producing a nanocomposite material based on copper, according to which multilayer carbon nanotubes is coated with copper by two-stage chemical activation in order to improve the surface strength of the metal matrix, then these copper-coated carbon nanotubes are mixed with a powder of metallic copper in an amount of 5-20 vol. % and use heating by microwaves for sintering [Rajkumar, K; Aravindan, S. Tribological studies on microwaves intered copper-carbon nanotube composites.-WEAR, v.2, p. 613-621, DOI: 10.1016 / j.wear.2011.01.01, Published: APR 4 2011].

This method uses the so-called modification of carbon nanotubes. By “modification” is meant the coating of carbon nanotubes with layers of organic or inorganic substances, or the decoration of their surface with nanosized particles of various nature.

Modification allows you to change the nature of the surface of nanotubes. In particular, grafting to the surface of nanotubes of various substances or functional groups ensures the compatibility of carbon nanotubes with the medium, which facilitates their introduction into this medium in the production of nanocomposite materials.

To obtain copper-based nanocomposite materials, copper surface modification of carbon nanotubes is used.

Thus, a known method of producing copper spheres with multilayer carbon nanotubes implanted in them [Xu Longshan, Chen Xiaohua, Pan Weiying, Li WenhuaYang, PuYuxing Electrostatic-assembly carbon nanotube-implanted copper composites spheres. NANOTECHNOLOGY, V18, IS 43, AR 435607, DOI: 10.1088 / 0957-4484 / 18/43/435607, OCT 31 2007].

The method includes combining copper ions with multi-walled carbon nanotubes at the molecular level and the formation of spheres after the recovery, nucleation and growth of copper ions that attach to the surface of the nanotubes. Composite spheres with implanted nanotubes allow nanotubes to avoid damage and effectively bind to the matrix. This unique spherical structure can serve as an excellent candidate as a powder for the production of a bulk composite reinforced with carbon nanotubes.

A known method of producing a composite material based on copper, according to which nanocomposites powders multilayer carbon nanotubes-copper with different volume fractions of nanotubes is prepared by chemical deposition of copper on the surface of nanotubes [Daoush, Walid M., Lim, Byung K., Mo, Chan B ., Nam, Dong H., Hong, Soon H., MATERIALS SCIENCE AND ENGINEERING A - STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING, 513-14, 247-253, DOI: 10.1016 / j.msea.2009.01.073, JUL 15 2009 ].

For this, nanotubes are preliminarily subjected to acid treatment, activation (sensitization), and chemical deposition of copper on their surface. Copper is deposited as a layer on the surface of the nanotube. Nanocomposite powder multi-walled carbon nanotube - copper is subjected to spark sintering by plasma.

This method of obtaining a nanocomposite material based on copper is the closest analogue of the claimed and adopted as a prototype of the invention. Obtained during the implementation of the method, the sintered composite material consists of modified nanotubes.

The prototype has the following disadvantages. Firstly, the final product obtained by the implementation of the method is sintered carbon nanotubes coated with copper, which means that the concentration of nanotubes in it is high, and it can only be used as a modifier, or ligature to obtain composite materials by adding it into the matrix material.

Secondly, if we consider the final product as the target material, then it cannot be used to produce parts that will be machined.

The invention solves the problem of creating a method for producing a composite material with high physical and mechanical properties based on a copper matrix, which can have a different concentration of carbon nanotubes and can be used as a finished nanocomposite material for further processing, including mechanical, or as a ligature for producing copper alloys.

The problem is solved in that a method for producing a composite material based on a copper matrix is proposed, which includes modifying carbon nanotubes with metal and compacting them into solid arrays, according to which carbon nanotubes are modified with metal from the series: copper, or lead, or tin, or zinc, or aluminum or silver, while the modified carbon nanotubes are mixed with copper powder having a fraction size of 3-10 μm and subjected to this mechanical activation mixture, then the mechanically activated mixture is compacted in TV rdye compression arrays, arrays and then solid is heated to a melting temperature in the absence of oxygen, is melted and cooled.

Here, the term “modified” carbon nanotubes means nanotubes with a changed surface nature, consisting of grafting ions of one or another of the named metals to the nanotube surface.

Carbon nanotubes can be modified by chemical deposition on their surface of a metal from the series: copper, or lead, or tin, or zinc, or aluminum, or silver, for which: - carbon nanotubes are treated with acid at a temperature of 20 - 100

° C;

- acid-treated carbon nanotubes are washed with water and dried;

- dried nanotubes are mixed with an aqueous solution of a salt of the corresponding metal and exposed to the resulting mixture by ultrasound;

- a mixture of nanotubes with an aqueous solution of a salt of the corresponding metal is heated to 90-100 ° C, evaporating the named solution to obtain nanotubes with a metal salt on their surface;

- nanotubes with a metal salt on their surface are heated in an inert medium to a temperature of 550-650 ° C with decomposition of the metal salt to metal oxides;

- nanotubes with metal oxides on their surface are reduced at a temperature of 550-650 ° C in a stream of methane, or a methane-hydrogen mixture to obtain nanotubes with metal on their surface.

The method can use single-walled and / or double-walled and / or multi-walled carbon nanotubes.

Metal salts can be: nitrates, acetates, metal carbonates.

The method is as follows.

Carbon nanotubes are treated with hydrochloric or nitric acid, or a mixture thereof, or other acids at a temperature of 20-100 ° C for, for example, 20 minutes. Treated nanotubes are washed with a neutral reagent, for example, distilled water, and dried at a temperature of 100-120 ° C for at least 30 minutes. Acid treated, washed and dried nanotubes are impregnated with an aqueous solution of a salt of the corresponding metal, for example, an aqueous solution of copper nitrate, or tin nitrate, or lead nitrate, or other suitable salts. After that, using a magnetic stirrer with heating from the resulting suspension, the liquid is evaporated at a temperature of 90-100 ° C to obtain a composite: "carbon nanotube - salt of the corresponding metal."

The resulting nanotubes are air dried at a temperature of the order of 100-180 ° C for at least 30 minutes. (drying time depends on the volume of the sample). After that, the dried nanotubes are heated in an argon medium to 550-650 ° C and kept at this temperature in a medium of hydrogen or a methane-hydrogen mixture for at least 30 minutes. In this case, the metal nitrate deposited on the surface of carbon nanotubes decomposes with the formation of metal oxide and then is reduced to metal. The result is nanotubes functionalized with the corresponding metal.

The obtained nanotubes in comparison with the initial ones have a surface modified with metal nanoparticles, affinity for the base metal - copper, which allows them to be mixed with copper. The surface of the nanotube, previously inert to copper, becomes sensitized to it. A chemical interaction occurs between the surface of a carbon nanotube and a metal, which is impossible without modifying the surface of the nanotubes, which makes it possible to uniformly incorporate nanotubes into a metal matrix.

Modification of carbon nanotubes by said metals can be carried out by other methods than those described. It is important that a change in the chemical composition of the surface of carbon nanotubes enhances their interaction with a dispersion medium. As a result, a more uniform distribution of nanotubes in the volume of the dispersion medium is observed, as a result of which the positive effect of their introduction into the matrix increases and the desired result is achieved at lower nanotube concentrations, which greatly expands the possibilities of their practical application.

The carbon nanotubes described above, modified with the aforementioned metals, are then used to obtain composite materials based on copper.

To do this, the modified carbon nanotubes are mixed with copper powder with a fraction size of 3-10 μm and subjected to mechanical activation by a power mill, for example, a centrifugal planetary, or ball, or bissor or magnetic. Upon activation, more thorough and uniform mixing of nanotubes with copper powder occurs.

After mechanical activation, portions are separated from the mass of the mixed material, which are pressed into solid arrays, for example tablets, of the nanocomposite material by cold pressing. Several tablets are stacked on top of each other in a graphite crucible and placed in a furnace chamber that provides isolation from oxygen. Next, a stack of tablets is heated in a furnace chamber to a temperature of at least 1085 ° C. At this temperature, the tablets melt, at which the metal melts, and the nanotubes are stored in the volume of the molten metal without burning out. After that, the melt is cooled to the solidification temperature and then to room temperature. The result is an ingot of nanocomposite material containing carbon nanotubes.

In the event that the carbon nanotubes were functionalized with tin, or aluminum, or silicon, or lead, a composite material is obtained bronze - carbon nanotubes. In the event that the nanotubes were functionalized with zinc, a composite material of brass — carbon nanotubes — is obtained. The resulting composite material in the form of an ingot can be machined, cast, and other processing methods in order to obtain various parts with high strength.

In addition, this material can be used as a ligature to obtain alloys.

Thus, the proposed method provides the production of a composite material based on copper in the form of an ingot, which can be used as a finished nanocomposite material for further mechanical or other processing, or as a ligature for the production of copper alloys.

Example 1

A copper powder having a fraction size of 3 μm in an amount of 100 g is subjected to mechanical activation in a planetary mill for 1 minute. After the mill, metallic copper is compacted by compression at room temperature and a pressure of 16 tons into solid arrays in the form of tablets. The diameter of the tablets is 18 mm. The tablets are loaded into a quartz tube with a diameter of 20 mm and placed in an oven, where in an argon atmosphere they are heated to a temperature of 1120 ° C. Under the influence of this temperature, the tablets melt. The resulting melt is cooled without air to room temperature. The resulting material contains May 100. % copper. The tensile strength of a sample of this copper is 87.5 MPa, the relative deformation at the break point is 8.33%.

Example 2

Copper modified nanotubes in the described manner, in the amount of 0.06 g, are mixed with copper powder having a fraction size of 3 μm, in the amount of 99.94 g, and this mixture is subjected to mechanical activation in a planetary mill for 1 minute. After the mill, the mechanically activated mixture is compacted by pressing at room temperature and a pressure of 16 tons into solid arrays in the form of tablets. The diameter of the tablets is 18 mm. The tablets are loaded into a quartz tube with a diameter of 20 mm and placed in a furnace, where in an argon atmosphere they are heated to a temperature of 1120 ° C. Under the influence of this temperature, the tablets melt. The resulting melt is cooled without air to room temperature. The resulting composite material based on a copper matrix contains 0.06 May. % carbon nanotubes and 99.94 May. % copper. The tensile strength of the sample from this composite material is 136.5 MPa, the relative deformation at the break point is 45.2%.

Example 3

Similar to example 2, it differs only in the number of carbon nanotubes introduced into the mechanically activated mixture modified with copper - 0.1 % The resulting composite material based on a copper matrix contains 0.1 May. % carbon nanotubes and 99.9 May. % copper. The tensile strength of the sample from this composite material is 141.9 MPa, and the relative deformation at the break point is 47.8%.

Example 4

Similar to example 2, it differs only in the amount of carbon nanotubes modified with copper introduced into the mechanically activated mixture — 0.4%. The resulting composite material based on a copper matrix contains 0.4 May. % carbon nanotubes and May 99.6. % copper. The tensile strength of the sample from this composite material is 130.6 MPa, and the relative deformation at the break point is 36.6%.

Example 5

Similar to example 2, it differs only in the amount of carbon nanotubes modified with copper introduced into the mechanically activated mixture — 0.6%. The resulting composite material based on a copper matrix contains 0.6 May. % carbon nanotubes and 99.4 may. % copper. The tensile strength of the sample from this composite material is 105.9 MPa, and the relative deformation at the break point is 11.0%.

Example 6

Similar to example 2, it differs only in that the carbon nanotubes are modified with lead, and the size of the copper fraction is 10 μm.

The resulting composite material based on a copper matrix contains 0.1 May. % carbon nanotubes, 0.03 May. % lead and 99.87 May. % copper. The tensile strength of the sample from this composite material is 124.3 MPa, the relative deformation at the break point is 30.0%.

Example 7

Similar to example 2, it differs only in that the carbon nanotubes are modified with tin, and the size of the copper fraction is 10 μm.

The resulting composite material based on a copper matrix contains 0.1 May. % carbon nanotubes, 0.03 May. % tin and 99.87 may. % copper. The tensile strength of the sample from this composite material is 121, 7 MPa, the relative deformation at the break point is 25.4%.

Example 8

Similar to example 2, it differs only in that the carbon nanotubes are modified with zinc, and the size of the copper fraction is 10 μm.

The resulting composite material based on a copper matrix contains 0.1 May. % carbon nanotubes, 0.03 May. % zinc and 99.87 may. % copper. Limit the strength of the sample from this composite material is 135.2 MPa, the relative deformation at the break point is 41, 1%.

Example 9

Similar to example 2, it differs only in that the carbon nanotubes are modified with aluminum, and the size of the copper fraction is 10 μm. The resulting composite material based on a copper matrix contains 0.1 May. % carbon nanotubes, 0.03 May. % aluminum and 99.87 May. % copper. The tensile strength of the specimen from this composite material is 90.4 MPa, the relative deformation at the break point is 9.3%.

Example 10

Similar to example 2, it differs only in that the carbon nanotubes are modified with silver, and the size of the copper fraction is 10 μm. The resulting composite material based on a copper matrix contains 0.1 May. % carbon nanotubes, 0.03 May. % silver and 99.87 may. % copper. The tensile strength of the sample from this composite material is 140.3 MPa, the relative deformation at the break point is 45.0%.

Table N ° 1 Mechanical properties of the composite material depending on the number of introduced carbon nanotubes modified with various metals

Relative

N8 Quantity and type Limit

deformation at a point is an example of a modifier based on strength,

rupture (elongation), and CNT pa

%

1 Control (pure C) 87.5 8.33

2 0.06% CNT - 0.018% Cu 136.5 45.2

3 0.1% CNT - 0.03% Cu 141.9 47.8

4 0.4% CNT - 0.12% Cu 130.6 36.6

5 0.6% CNT - 0.18% Cu 105.9 11.0

6 0.1% CNT - 0.03% Pb 124.3 30.0

7 0.1% CNT - 0.03% Zn 121.7 25.4

8 0.1% CNT - 0.03% Sn 135.2 41.1

9 0.1% CNT - 0.03% AI 90.4 9.3

10 0.1% CNT - 0.03% Ad 140.3 45.0

Claims

CLAIM

1. A method of producing a composite material based on a copper matrix, including the modification of carbon nanotubes with metal and compacting them into solid arrays, characterized in that the nanotubes are modified with metal from the series: copper, and / or lead, and / or tin, and / or zinc, and / or aluminum and / or silver, after which the modified carbon nanotubes are mixed with copper powder having a particle size of 3-10 μm and subjected to this mechanical activation, and the mechanical activated mixture is compacted by compression into solid arrays, which are then heated, at least at least to the melting point in the absence of oxygen, melt and then cool.

2. The method according to claim 1, characterized in that the carbon nanotubes are modified by chemical deposition of metal on their surface, for which:

- carbon nanotubes are treated with acid at a temperature of 20 -

100 ° C

- acid-treated carbon nanotubes are washed with water and dried,

- dried nanotubes are mixed with an aqueous solution of a salt of the corresponding metal and exposed to them by ultrasound,

- a mixture of nanotubes with an aqueous solution of a salt of the corresponding metal is heated to 90-100 ° C, evaporating the named solution to obtain nanotubes with a metal salt on their surface,

- nanotubes with a metal salt on their surface are heated in an inert medium to a temperature of 550-650 ° C with decomposition of the metal salt to metal oxides,

- nanotubes with metal oxides on their surface are exposed to methane, or a methane-hydrogen mixture at a temperature of 550-650 ° C to produce nanotubes with metal on their surface.

3. The method according to claim 1, characterized in that use carbon nanotubes single-walled and / or double-walled, and / or multi-walled.

4. The method according to claim 1, characterized in that the solid masses are heated to a temperature not lower than 1085 ° C in an inert gas atmosphere.