RU2471012C1 - Composite powder material - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: composite powder material contains matrix representing metal and/or alloy on the basis of metal, and/or intermetallic compound, and disperse filler in the form of reducing graphite oxide.

EFFECT: material has high physic and mechanical and/or functional properties, has disperse homogeneous structure and high operating reliability.

2 cl, 5 tbl, 5 ex

Description

The invention relates to the field of powder metallurgy, specifically to the manufacture of composite nanomaterials, and can be used in various fields of technology, for example, when creating spacecraft and objects.

Carbon-hardened powder composite materials are known, in particular aluminum-based powder composite material (RF patent No. 2353689, BI No. 12, 04/27/2009) containing silicon, nickel, beryllium, aluminum oxide and silicon, carbon. Carbon in the form of electrode graphite plays the role of a technological lubricant during mechanical alloying, subsequently interacting with aluminum and silicon to form thin carbides. The carbon content in an amount of 0.5-2 wt.% Is determined by the need to prevent clumping of powder particles during mechanical alloying. The disadvantage of the material is the low ductility, including technological, in the manufacture of blanks, which does not allow to obtain a material with a density higher than 98% of the theoretical (calculated) density γ _t and reduces mechanical properties. (The density calculated by the additivity rule based on the volume fractions of the components in the composite material is accepted as theoretical

γ _t = 1 / (c _m1 / γ ₁ + c _m2 / γ ₂ + c _m3 / γ ₃ + ... + c _mn / γ _n ),

where c _m1 ... c _mn are the mass fractions of the components of the alloy in the composition,

γ ₁ ... γ _n is the density of the alloy components).

Known powder composite materials reinforced with nanosized oxides, carbides and / or nitrides. In particular, a composite material with a matrix of a metal selected from the group consisting of aluminum, magnesium or their alloys, and 20-80 vol.% Reinforcing dispersed filler made in the form of reinforcing alumina nanofibers coated with an amorphous carbon film is known (RF patent No. 2374355, C22C 49/14, publ. 11/27/2009). The disadvantage of the material is its low manufacturability (a set of properties that determine the suitability for achieving optimal production costs for given quality indicators), for example, the need to cover reinforcing nanofibres with an amorphous carbon film.

A highly conductive composite material with a filler made of mechanically peeled (stratified) graphene is known (graphene is a material representing one atomic layer of graphite) (application US 2011284805 dated November 24, 2011). According to the source of information, the material is highly porous, which is its drawback.

Nanocarbon hardened powder composite materials are known, for example a graphene / metal powder composite material including a matrix (base metal) and graphene dispersed therein (application US 2011256014 (A1) / US 201113086749, 20110414 / KR 20100034152, 20100414 dated October 20, 2011 g.). Graphene behaves like a matrix hardener. The graphene particles in the matrix have a volume content of 0 to 30%, corresponding to a level at which a structural change in graphene or a reaction between graphene particles is avoided. The disadvantage of the material is the high cost and lack of production in Russia.

The closest to the proposed technical essence and the achieved effect is a powder composite material reinforced with carbon nanotubes (CARBON 49 (2011), p.533-544). The material contains a matrix of aluminum or alloys based on it of the Al-Ni, Al-Cu-Mg, Al-Si systems and a dispersed filler, which uses carbon nanotubes (CNT) in an amount of up to 12.5%. The disadvantage of the material is low manufacturability due to the problem of providing a chemical bond between the elements of the metal matrix and carbon nanotubes during manufacture, the absence or weakening of which reduces the effectiveness of hardening.

The task to which the invention is directed is to improve manufacturability in production and increase the physicomechanical properties of the powder composite material.

The technical result consists in improving the physical and mechanical properties of the material and is due to an increase in the uniformity of the distribution of the dispersed filler and to an improvement in the chemical bond between the elements of the metal matrix and the filler. In addition, through the use of cheaper reduced graphite oxide, production costs are reduced for given quality indicators of the material.

This is achieved by the fact that the powder composite material consists of a matrix containing at least one metal and / or a metal-based alloy and a dispersed filler of nanosized carbon, while the matrix contains at least one metal and / or a metal-based alloy - and / or an intermetallic compound, and reduced carbon monoxide is used as the nanoscale carbon, the reduced graphite oxide may be functionalized.

Reduced graphite oxide (FOG) is a structured modification of partially or fully reduced graphite oxide, in which, after reduction, along with new functional groups or double bonds, the old hydroxyl groups remain. FOG consists of mono- or small-layer particles with a thickness of 1-10 atomic layers, the length and width of which are much greater than their thickness, having a defective or distorted hexagonal crystal lattice with an X-ray amorphous structure that does not contain a graphite peak in the x-ray diffraction pattern during x-ray phase analysis. The FOG structure determines a number of its specific properties: high lubricity, heat and electrical conductivity, developed specific surface area, the possibility of incorporation (alloying) in the process of synthesis of atoms or groups of atoms (nanoclusters) of various metals and compounds (functionalization). The latter is an important factor for chemical interaction with a metal matrix having a similar structure. Moreover, due to the defective structure, the cost of FOG is an order of magnitude lower than the cost of known nanocarbons, in particular graphenes and carbon nanotubes.

Examples of specific application.

Example 1

Powder composite material containing a matrix of aluminum grade A7 and dispersed filler (DN) in the form of VOG

The powder matrix of the alloy with a dispersion of ≤50 μm, obtained by gas spraying from a melt, and FOG in the form of particles with a thickness of 0.4-4 nm, length and width of 1-5 μm was treated for 45 min in an attritor with an energy saturation of 3 kW / kg. The resulting powder composition was compacted in vacuo at 10 ^-4 -10 ^-5 mm Hg. at a temperature of 450 ° C and a pressure of 130 MPa. Physico-mechanical properties of compact briquettes made of composite material are shown in table 1.

Table 1 No. p / p Material Composition, wt.% Processing time, h, surfactant * Density σ _B **, MPa δ ₅ ***,% Matrix DN g / cm ³ % calculation one Proposed Al VOG, 2% 0.75, without surfactant 2.69 one hundred 148-150 24 2 Proposed Al VOG, 24% 0.75, without surfactant 2.60 one hundred 230-250 2,4 3 Prototype Al CNT, 0.5-5% 2-6, surfactant there is no data 94-99 84-140 7-28 four Prototype Al CNT, 10% 2-6, ethanol there is no data 96 80 16 * Surfactants - surfactants (technological additives, plasticizers, for example stearin). ** σ _B - temporary tensile strength (tensile strength), *** δ ₅ is the elongation determined on a five-fold specimen according to GOST 1497.

An analysis of the results shows that the proposed material has a higher manufacturability compared to the prototype in manufacturing, and, without requiring the use of surfactants during machining in the attritor, it provides a density of 100% of the calculated, 5-40% increased mechanical strength and allows to reduce the processing time by 2 -8 times.

Example 2

A powder composite material containing a matrix of chemically pure copper powder with a particle size of ≤2 μm and a dispersed filler in the form of a functionalized FOG containing copper nanoclusters ranging in size from 20 to 500 nm in an amount of 1-5%

The matrix powder and functionalized VOG in the form of particles 0.4–4 nm thick, 1–5 μm long and wide were processed for 30 min in a vibratory mixer and sieved on a vibrating sieve through a 004 mesh according to GOST 6613. From the obtained powder composition by cold pressing in air at a pressure of 300 MPa samples were made with a diameter of 15 and a height of 25 mm. Physico-mechanical properties of the samples are shown in table 2.

table 2 No. p / p Material Composition, wt.% Hardness HB λ, * W / m Matrix DN condition MPa one Proposed Cu 50% VOG functionalized cold pressed 60 818.6 2 Proposed Cu 20% VOG functionalized cold pressed 40 1497.7 3 Copper M0 - annealed 35 401 * thermal conductivity.

The proposed material has a higher thermal conductivity compared to copper: ≈2 times with a ratio of volumes of Cu to FOG 1: 1 and ≈4 times with a ratio of volumes of Cu to FOG 1: 4. The minimum content of the matrix material is determined by the need to maintain a strong metal frame.

Example 3

A powder composite material containing a matrix of an Al-Al ₃ Ni alloy in an amount corresponding to 1-3 wt.% Ni, 0.5-1 wt.% Of transition metals (Cr, Zr, V) and a dispersed filler in the form of FOG

The powder matrix of the alloy with a dispersion of ≤300 μm obtained by centrifugal melt spraying and FOG in the form of flakes with a thickness of 0.4-4 nm, length and width of 1-5 μm was treated for 45-75 min in an attritor with an energy saturation of 3 kW / kg. The resulting powder composition was compacted in vacuo at 10 ^-4 -10 ^-5 mm Hg. at a temperature of 480 ° C and a pressure of 130 MPa. Physico-mechanical properties of compact briquettes made of composite material are given in table 3.

Table 3 No. p / p Material Composition, wt.% Processing time, h, surfactant Density σ _B , MPa δ ₅ ,% Matrix DN g / cm ³ % calculation one Proposed Al-Ni-PM VOG, 2.5% 0.75-1.5 without surfactant 2.75 one hundred 330 4,5 2 Prototype Al-1% Ni CNT, 6.2% not given not given 95.4 213 - 3 Prototype* Al-1% Ni CNT, 4.34% ** not given 97 337 3.6 * Nickel particles in aluminum are obtained by chemical deposition during annealing, CNT are grown by chemical vapor deposition; ** sintering at 600 MPa, 640 ° С, 3 h, prepressing 2 GPa, formation of Al ₄ С ₃ at 850 ° С, 2 h.

The proposed material has a higher manufacturability in comparison with the prototype in manufacturing: it provides a density of 100% of the calculated and 40% increased mechanical strength. Close strength on the material of the prototype (No. 3, see table 3) was obtained with twice as much CNT content as compared with FOG and a significant complication of the technology for producing the material (see note to table 3).

Example 4

Powder composite material for precision instruments with a reduced temperature coefficient of linear expansion (TKLP), containing an Al-42.5% Si-3% Ni alloy matrix and a dispersed filler in the form of VOG

Al-20 mass% Si and Al-20 mass% Ni alloy powders with a dispersion of ≤50 μm obtained by gas spraying from a melt, metal silicon or silicon carbide with a dispersion of ≤2 μm and VOG in the form of particles with a thickness of 0.4-4 nm , length and width of 1-5 microns were treated for 45-75 minutes in the attritor with an energy saturation of 3 kW / kg VOG in the composition is used as a technological additive. The resulting powder composition was compacted in vacuo at 10 ^-4 -10 ^-5 mm Hg. at a temperature of 535 ° C and a pressure of 130 MPa. Physico-mechanical properties of compact briquettes made of composite material are given in table 4.

Table 4 No. p / p Material Composition, wt.% Processing time, h, surfactant Density σ _B , MPa TECL, 1 · 10 ^-6 1 / ° C δ ₅ ,% Matrix DN g / cm ³ % calculation one Proposed Al-Si-Ni VOG, 0.5 0.75 without surfactant 2,599 one hundred 258 9.94-10.75 0.17 one Proposed M-Si-SiC-Ni VOG, 0.5 0.75 without surfactant 2,567 one hundred 250 10.44-10.46 0.18 2 Prototype* Al-23% Si CNT, 12.5 there is no data 2,556 there is no data 83 15.37 0.19

An analysis of the results given in Table 4 shows that the proposed material can effectively carry out mechanical alloying without hydrocarbon surfactants, while compaction provides a density of 100% calculated. In this case, the strength is three times the strength of the prototype with equal elongation, despite the twice as high silicon content, and the thermal expansion coefficient of the material is reduced by 1.5 times.

The lower limit of the VOG content is determined by the necessary lubricating effect during mechanical alloying, which prevents clumping of powder particles. The upper limit is determined by the requirement to ensure the necessary physical and mechanical properties.

The proposed material as a result of mechanical alloying has a structure with a dispersed filler uniformly distributed in the matrix. The high lubricating properties of VOG allow it to be used as a surfactant. Moreover, the amount of FOG required to activate mechanical alloying is significantly less than the amount of graphite (in the form of electrical, electrode, or soot), and there is no need to use surfactants based on hydrocarbons that are sources of harmful hydrogen in the material. Unlike carbon nanotubes, VOG does not form bundles. The latter applies both to cases where VOG is used only in an amount sufficient for the lubricating effect, and when it is used for hardening

Example 5

A powder composite material containing a matrix of an alloy of Mg-6% Zn-0.5% Zr (granulated MA14 - MA14 g) or Mg-2% Zn-0.7% Zr-1.6% Cd-6.5% Y (granulated VMD10 - VMD10 gr) and dispersed filler in the form of VOG.

Granules of alloys Mg-6.5 wt.% Zn-0.5 wt.% Zr or Mg-2 wt.% Zn-0.7 wt.% Zr-1.6 wt.% Cd-6.5 wt.% Y dispersion ≤1.5 mm, obtained by centrifugal spraying of the melt into liquid nitrogen, and FOG in the form of particles with a thickness of 0.4-4 nm, length and width of 1-5 μm were processed for 30 min in a vibratory mixer and sieved on a vibrating screen through mesh 15 and 004 according to GOST 6613. A powder composition with a particle size distribution of ≤1.5 mm but ≥40 μm was processed into a pressed semi-finished product according to the technology indicated in table 5.

Table 5 No. p / p Material Composition, wt.% Metallurgical redistribution Density, g / cm ³ σ _B , MPa Matrix DN one Proposed MA14 gr FOG, 0.5% Compacting in vacuum, 300 ° С, 6 MPa, pressing 280 ° С, _in 4 1,795 ≥350 2 Proposed VMD10 gr VOG, 1% Compacting in vacuum, 300 ° С, 6 MPa, pressing 350 ° С, _in 20 1,886 ≥350 3 Granular MA14 gr Compacting in a capsule, 320 ° С, 400 MPa, pressing 320 ° С, _in 4 1.68 320-330 four Granular AMD 10 UAH Compacting in vacuum, 380 ° C, 6 MPa, pressing 380 ° C, _in 20 1,801 ≥330 5 Cast MA14 - Pressing 320 ° C, K _in 4 1.76 290-330 6 Cast VMD10 - Pressing 380 ° C, _in 20 1.86 320-330 to _in - coefficient of drawing during pressing.

The proposed material has a higher density of pressed semi-finished products in comparison with the known granular and cast alloys (the effect is 0.3-2% compared to cast and 6-6.4% compared to granular versions of alloys that do not contain FOG). FOG makes it possible to reduce the pressing temperature by 30–40 ° C. As a result, mechanical strength increases by 6–20%.

Thus, the invention allows to significantly improve manufacturability in the manufacture and to obtain a powder composite material with a dispersed homogeneous structure and increased physical and mechanical (density, strength, etc.) and / or functional properties, to increase its operational reliability.

Claims (2)

1. A powder composite material containing a metal matrix and a dispersed filler in the form of nanosized carbon, characterized in that it contains a metal and / or metal-based alloy and / or intermetallic as a matrix, and reduced graphite oxide as a nanosized carbon. 2. The powder composite material according to claim 1, characterized in that it contains functionalized reduced graphite oxide as reduced graphite oxide.