RU2773060C1 - Composite material based on powder copper - Google Patents

Abstract

FIELD: non-ferrous metallurgy.

SUBSTANCE: invention relates to the field of non-ferrous metallurgy, in particular to the compositions of erosion-resistant composite materials based on copper, obtained by powder metallurgy and intended for the manufacture of high-performance electrode-tools for electroerosive machining of metallic materials, mainly hard-to-machine and, above all, for piercing them deep holes and small grooves. Composite material based on powdered copper contains, wt.%: aluminum 0.81-0.95, graphite 0.10-0.20, copper oxide 3.39-3.49, copper - the rest.

EFFECT: invention is aimed at increasing the erosion wear resistance of the material and increasing the productivity of the process of electroerosive machining with electrode-tools from it.

1 cl, 2 tbl, 1 dwg

Description

The invention relates to the field of non-ferrous metallurgy, in particular to the compositions of erosion-resistant composite materials based on copper, obtained by powder metallurgy and intended for the manufacture of highly efficient electrode-tools for electroerosive machining of metal materials, mainly difficult to machine and, above all, for piercing them deep holes and small grooves. Can also be used for resistance welding electrodes.

One of the most complex operations of mechanical processing of materials are operations to obtain a number of through and / or blind holes and grooves of small sizes (0.1-3.0 mm) in various products, for example, in the manufacture of grids of electrovacuum devices, when obtaining holes on the front and trailing edges of turbine blades of aircraft engines, when making holes in the protective grids of air intakes of aircraft turbines, when making microscopic holes in the nozzles of the fuel supply system, when making holes in spinnerets for the manufacture of synthetic (viscose) and carbon fibers, in the production of medical instruments, parts of electronic systems and many other products that have minimal hole sizes and require high accuracy.

Particular difficulty arises when these holes have a depth equal to more than 30 hole diameters (for example, 150 mm with a hole diameter of 4 mm), and the material of the product is hard-to-cut high-strength steels and, moreover, hard alloys [Typical EDM operations. Central metal portal of the Russian Federation, c. 4 and 5 (found on 2021-11-08 at <https://metallicheckiy-portal.ru/articles/obrabotka/elektro-erozionnaya/tipovie_operacii/4>) and OVCHINNIKOV, D.V., MORGUNOV, Yu.A. Electroerosive piercing of deep holes of small diameter. Rhythm of mechanical engineering. 2018. No. 10, p. 28-33 (found on 2021-11-08 at <https://ritm-magazine.ru/ru/magazines/2018/zhurnal-ritm-mashinostroeniya-10-2018#page-1>)]. Making such holes with conventional machining methods is considered to be extremely difficult or even impossible.

In recent years, this problem has been successfully solved by using the method of electroerosive "drilling" of holes of small diameter, which is one of the options for the technology of electrical discharge machining (EDM) of metallic materials. The essence of this method lies in the electroerosive flashing of a hole with a long electrode-tool, which continuously rotates in the cartridge in the presence of a constant stream of distilled or deionized water pumped through the electrode-tool or the gap between it and the workpiece as a flush (washing out of particles from the processing zone) and dielectric.

EDM "super drill" ("super drill" or "hole popper") allows you to make holes of high accuracy with a diameter of 0.2 ... 3.0 mm up to 100 mm deep, but in some types of "super drills" it is possible to make holes within 1/200…1/250 [The principle of operation of the EDM superdrill. Metalworking portal WikiMetall.Ru (found 2021-11-08 in <https://wikimetall.ru/oborudovanie/elektroerozionnaya-superdrel.html>)].

Tool electrodes, the working part of which is a negative copy of the machined surface of the product, taking into account the necessary technological allowances, are one of the main elements involved in the electroerosive process. The physical, mechanical and operational properties of the material from which they are made have a primary impact on the stability of the electroerosive process, its efficiency, productivity and processing accuracy.

As a result of the impact of a current pulse during electroerosive machining, not only the material being processed, but also the material of the electrode-tool melts. Therefore, it is subject to special requirements for electrical erosion resistance and electrical conductivity in the temperature range from room temperature to the melting temperature of the electrode-tool material. Since long and thin electrode-tools are used for electroerosive "drilling" of deep holes of small diameter, to ensure the rigidity of their design, which can withstand mechanical and thermal deformations (total deformation should not exceed 0.3% of the tolerance for the main dimensions of the workpiece), the material tool electrodes must also have mechanical strength, especially bending strength, and not only at room temperature, but also at elevated temperatures. This requirement is due to the periodic contact of the electrode-tool with the surface to be treated, as well as the electrodynamic forces arising from the electroerosive discharge. [EKATERINICHEV, A.L. Substantiation of the parameters of the electrode-tools and the conditions of electroerosive microformation: abstract of diss. ... cand. tech. Sciences. Tula. Tul. state un-t. 2007. 19 p., especially p.7 (found 2021-11-12 in <file:///C:/Users/ShEP/Downloads/autoref-obosnovanie-parametrov-elektrodov-instrumentov-i-uslovii-elektroerozionnogo-mikroformoobrazo .pdf>)].

In addition, the material must have heat and corrosion resistance and not emit any toxic substances under the action of high temperatures during the discharge [OGLEZNEV, N.D. Development of composite materials for electrode-tools with improved performance for processing metal alloys: diss. …cand. tech. Sciences. Permian. Perm National research polytechnic un-t, 2015, 137 pp., especially p.13,14,16 (found 2021-11-08 at http://research.sfu-kras.ru/sites/research.sfu-kras.ru/files/ Dissertaciya_Ogleznev.pdf>)].

Carbon-graphite tool electrodes, due to their high EDM resistance, low cost, availability of purchase and good machinability, have found wide application in the EDM of carbon and tool steels, as well as nickel-based heat-resistant alloys [Basic information about EDM. Central metal portal of the Russian Federation, c. 7 and 8 (found 2021-11-08 at https://metallicheckiy-portal.ru/articles/obrabotka/elektro-erozionnaya/osnovnie_svedenia/7)]. However, in the case of machining of hard alloys and refractory materials based on tungsten, molybdenum and a number of other materials, especially in the finishing modes of EDM, carbon graphite tool electrodes do not provide high performance due to the low stability of the electroerosive process. In addition, when piercing holes of small diameter and narrow grooves, such tool electrodes are of limited use due to their low mechanical strength, and their use for EDM “drilling” of deep holes of small diameter is practically impossible due to the extremely fragility of the design of long and thin tool electrodes.

по сравнению с углеграфитовыми электродами-инструментами [Основные сведения об электроэрозионной обработке. Центральный металлический портал РФ, c. 7 (найдено 2021-11-08 в <https://metallicheckiy-portal.ru/articles/obrabotka/elektro-erozionnaya/osnovnie_svedenia/7>)].Copper and materials based on it make up the main part of the metal materials used for electrode-tools of electroerosive machining and, in particular, electroerosive "drilling" of deep holes of small diameter, including in products made of high-strength tool steels and hard alloys. The most commonly used rods and rolled products are made of electrolytic copper grades M1 and M2, which have high electrical and thermal conductivity. The use of MP-15 powder copper tool electrodes with a relative porosity of 15% makes it possible, when processing with rectangular pulses, up to 1.5 times in comparison with M1 compact copper tool electrodes, to increase the material removal rate of the product and increase the tool electrode durability [OGLEZNEVA, S.A., Ogleznev, N.D. Development of the material of the electrode-tool for electroerosive piercing. Modern problems of science and education. Online edition. 2014. No. 2. ISSN 2070-7428, see Introduction (retrieved 2021-11-08 in <https://science-education.ru/ru/article/view?id=12692>)]. However, sintered electrode-tools made of powdered copper with such a porosity and, especially, of a circular cross section, are almost impossible to make long and thin, and long and thin electrodes made of compact copper, obtained by extrusion and/or drawing, have a relative volumetric electroerosive wear of 6... 10 times

compared with carbon-graphite electrode-tools [Basic information about electroerosive machining. Central metal portal of the Russian Federation, c. 7 (found 2021-11-08 at <https://metallicheckiy-portal.ru/articles/obrabotka/elektro-erozionnaya/osnovnie_svedenia/7>)].

Closest to the proposed invention analogue (prototype) is a composite material based on powdered copper containing graphite in the amount of 0.4 wt.% [OGLEZNEV, N.D. Development of composite materials for electrode-tools with improved performance for processing metal alloys: diss. … cand. tech. Sciences. Permian. Perm National research polytechnic un-t. 2015. 137 p., especially p. 54 (Table 3.4), p. 94 (Table 5.1), p. 97 (Fig. 5.4, b), p. 100 (Fig. 5.7, b), p. 103 (Table 5.2) (found on 2021-11-08 at <http://research.sfu-kras.ru/sites/research.sfu-kras.ru/files/Dissertaciya_Ogleznev.pdf>)]. Since graphite does not interact with copper even at high temperatures: copper does not dissolve in graphite (like carbon in copper), this composite material is, in fact, a mechanical mixture (pseudo-alloy), the physical properties of which are additively made up of physical properties phases (components) of the material [AVRAMOV, Yu.S., Shlyapin, A.D. New composite materials based on immiscible components: preparation, structure, properties. Moscow. MGIU. 206 c. (found 2021-11-09 in <https://booksee.org/book/1471475>)], and its production is carried out by the method of powder metallurgy by transverse to the axis of the pressing part at a pressure of 600 MPa, a mixture of electrolytic copper powder of grade PMS prepared in advance in a mixer -1 (GOST 4960-75) and dry colloidal graphite grade S-1 (TU 113-08-48-63-90), subsequent annealing of the resulting sample blank with dimensions of 6x6x50 mm in a vacuum furnace at a temperature of 700 ° C, its repeated pressing at pressure of 600 MPa and final sintering in a vacuum furnace at a temperature of 1070±10 °C for 2 hours. residual porosity of the material. The performance of tool electrodes made of this material when piercing Kh12F steel containing chromium and tungsten in different operation modes is 6–35% higher than the performance of electrodes made of M1 grade copper. At the same time, the relative wear of tool electrodes made of this composite material is 15 times less than the wear of tool electrodes made of M1 grade copper.

However, the use of this material in tool electrodes for electroerosive "drilling" of deep holes is effective if the size of the cross section of the tool electrode is not less than 3 mm. As the transverse dimensions decrease, the strength will decrease, the fragility of the tool electrodes will increase, and the process of their transverse pressing and sintering will become more complicated, especially for tool electrodes of circular cross section.

The task to be solved by the claimed invention is the creation of an erosion-resistant composite material based on powdered copper, intended for the manufacture of highly efficient electrode-tools for electroerosive machining of metal materials, mainly hard-to-machine, and above all, for flashing deep holes and grooves into them. small sizes.

The technical result of the claimed invention is to achieve, on the basis of a balanced chemical composition and structure of the material, its increased physical, mechanical and operational characteristics and, above all, electroerosive resistance and productivity of the electroerosive machining process, as well as properties that make it possible to obtain long and thin electrodes from the material - tools.

The specified technical result is achieved due to the fact that the composite material based on powdered copper containing graphite additionally contains aluminum and copper oxide in the following ratio, wt.%:

Aluminum 0.81-0.95 Graphite 0.10-0.20 copper oxide 3.39-3.49 Copper rest

The prior art does not know analogs with an identical set of features.

The material according to the claimed invention is made from the initial powder mixture prepared by mixing in a mixer of the "drunken barrel" type for 1 hour dosed portions of powder of electrolytic copper grade PMS-1 (GOST 4960-75), aluminum powder grade PP-1 (GOST 5592-71 ), powder of copper oxide (II) (copper oxide) of ChDA qualification GOST 16539-79 and powder of dry colloidal graphite grade S-1 (TU 113-08-48-63-90). The initial powder mixture thus prepared is treated in the atmosphere of the working chamber of the attritor for 1 hour with a rotor speed of 600 min ^-1 , the degree of filling of the working chamber with grinding balls and the powder mixture equal to 0.7. The granules obtained in the attritor are placed in a semi-hermetic steel container, the bottom of which is filled with a charcoal carburizer (GOST 2407-83), which is a gas mixture generator (CO + CO ₂ ), and then the container is placed in a chamber electric furnace heated to 870 ° C, where at this temperature is maintained, depending on the weight of the granules, from 3 hours to 5 hours. The resulting granules are subjected to cold compaction in a hydraulic press in a rigid matrix according to a two-sided pressing scheme with a pressure of 600 MPa into briquettes, which are then heated in a furnace in a protective atmosphere to a temperature of 750 ° C, kept at this temperature for 30-40 minutes and then extruded in a heated state. into bars from a hydraulic press container heated to 450°C into a conical hard alloy die. The hole (point) in this matrix can be made in the form of the required profile (circle, square, rhombus, etc.) of the cross section of the rod, which is a blank for making tool electrodes from it. Since hot-extruded rods are obtained up to 4000 mm long, several long electrode blanks are made from them at once for electroerosive "drilling" of deep holes, and the minimum diameter of such rods is 1 mm. If a smaller diameter of the tool electrode is required, then it is obtained by subjecting the rod to drawing, in which, simultaneously with a decrease in diameter, increased accuracy of this size and a high class of cleanliness of the side (working) surface of the tool electrode are provided.

During the processing of the initial powder mixture of powders in the oxygen atmosphere of the working chamber of the attritor and further thermal deformation processing of the obtained granules into hot-extruded rods, aluminum is oxidized (mechanochemical synthesis) and aluminum oxide Al ₂ O ₃ is formed in the material according to the reaction:

2Al+3/2 O ₂ \u003d Al ₂ O ₃ .

During processing in an attritor and further thermal deformation processing of the granules obtained in it, not only aluminum, but also copper powder is oxidized with the formation of CuO and Cu ₂ O oxides:

2Cu+O ₂ \u003d 2CuO,

where CuO is copper oxide (II) (copper oxide), which is formed in the form of black crystals, starting from a temperature of 60 ... 70 ° C.

4CuO → 2Cu ₂ O + O ₂ ,

where Cu ₂ O is copper oxide (I) (copper oxide), obtained by decomposition of CuO when heated to 1100 ° C in the form of reddish-brown crystals.

чем медь сродством к кислороду, восстанавливает медь из ее оксидов с одновременным образованием собственного оксида:Thus, in the process of obtaining a material, its structure contains, in addition to dynamically thermally stable Al ₂ O ₃ strengthening particles, also a significant amount of copper oxide particles, the dimensions of which are orders of magnitude larger than the dimensions of aluminum oxide particles and they greatly reduce the electrical conductivity of the material. aluminum, having

than copper affinity for oxygen, restores copper from its oxides with the simultaneous formation of its own oxide:

3CuO + 2Al \u003d 3Cu + Al ₂ O ₃ ,

Cu ₂ O + 2Al \u003d 6Cu + Al ₂ O ₃ .

However, in order to completely oxidize aluminum, as a rule, there is not enough oxygen in the air in the sealed working chamber of the attritor and the copper oxides formed during processing in it. Since residual aluminum and aluminum in a solid solution of copper lower the electrical conductivity of copper more than its oxides, according to the present invention, copper (II) oxide (copper oxide) CuO, which is an additional source of oxygen for the complete oxidation of aluminum, is specially introduced into the initial powder mixture.

Thus, the resulting material consists of a plastic base in the form of a copper matrix and aluminum oxide particles evenly distributed in it, the formation of which occurs according to the above four solid-phase reactions. Research done at the source [RU 2746016 C1 (VLADIMIROVA, Yu.O. et al.) 04/05/2021, fig. 1, p. 13, line 40], showed that alumina has a modification γ-Al₂O₃, and its particles have the size of a nanodispersed level - no more than 50 nm. Dynamically thermally stable aluminum oxide nanoparticles uniformly distributed in the matrix do not chemically interact with the matrix and do not dissolve in it up to its melting temperature; an increase in the strength properties of the material is provided. When the material is heated, these particles block the growth of grains, which provides a high recrystallization temperature, which characterizes the heat resistance of the material [GOLDSTEIN, M.I., FARBER, V.M. Dispersion hardening of steel. M. Metallurgy. 1979. p. 127-139 (found 2021-11-12 in <https://www.studmed.ru/goldshteyn-m-i-farber-v-m-dispersionnoe-uprochnenie-stali_bb2887d3ebc.html>)].

In addition to copper oxides, the formation conditions of which are indicated above, the granules obtained in the attritor also contain copper hydroxides Cu(OH)₂, which are oxide films that were initially present on copper powder particles and were destroyed (torn off) during processing in an attritor. In addition, due to the high temperature (80...120°C) in the working chamber of the attritor, the moisture adsorbed on the surface of the initial particles of copper powder partially took part in the oxidation of copper with the formation of its hydroxide. Since the sizes of copper hydroxides Cu(OH)₂ one or two orders of magnitude greater than the dimensions of the formed aluminum oxide γ-Al₂O₃, their contribution to strengthening the material and achieving its high heat resistance and strength is negligible. But on the other hand, copper hydroxides significantly reduce the electrical conductivity of the material, and therefore they are considered harmful impurities. To get rid of them, graphite is present in the initial powder mixture, part of which is C_in during the heating of the pellets in a semi-hermetic container, it recovers copper from its hydroxide according to the reaction:

2Cu(OH) ₂ + C \u003d 2Cu + CO ₂ ↑ + H ₂ O ↑.

At the same time, the formed carbon dioxide CO ₂ and water H ₂ O in the form of superheated steam are removed through intragranular and intergranular pores into the atmosphere. A protective atmosphere in the form of gases CO ₂ (CO) to prevent the oxidation of the granular briquette before hot extrusion is created by another part of graphite _СЗ , reacting with atmospheric oxygen:

C _s + O ₂ →CO ₂ (CO) ↑.

The presence of this protective atmosphere during heating of granular briquettes before hot extrusion provides the material with good electrical conductivity.

In accordance with the described technology, hot-extruded bars of the claimed material with a square section of 9.40 _-0.36 x 9.40 _-0.36 mm of various compositions were manufactured with the content of components in them within the limits indicated in Table 1.

Table 1 Components Material compositions, wt.% No. 1 No. 2 Number 3 No. 4 No. 5 No. 6 No. 7 No. 8 No. 9 Aluminum 0.81 0.81 0.81 0.88 0.88 0.88 0.95 0.95 0.95 Graphite 0.10 0.15 0.20 0.10 0.15 0.20 0.10 0.15 0.20 copper oxide 3.39 3.44 3.49 3.39 3.44 3.49 3.39 3.44 3.49 Copper 95.70 95.60 95.50 95.63 95.53 95.43 95.56 95.46 95.36

Also, in accordance with the technology described in the information source [OGLEZNEV, N.D. Development of composite materials for electrode-tools with improved performance for processing metal alloys: diss. … cand. tech. Sciences. Permian. Perm National research polytechnic un-t. 2015. 137 p., especially p. 43, 44, 50-52 (retrieved 2021-11-12 at <http://research.sfu-kras.ru/sites/research.sfu-kras.ru/files/Dissertaciya_Ogleznev.pdf>)] prismatic samples were made dimensions 9.40 _-0.36 x 9.40 _-0.36 x 50 mm from a material that is the closest analogue (prototype) of the claimed material - a composite material based on powdered copper containing graphite in an amount of 0.4 wt.%.

From the manufactured hot-pressed rods of the claimed material and samples of the prototype material, the corresponding samples were made by machining methods for testing to determine the physical, mechanical and operational properties of both materials.

The electrical conductivity of materials before and after annealing of their samples at 850 ± 5°C for 1 h in argon was determined on the basis of GOST 7229-76. The obtained values of the electrical resistance of the materials were recalculated into the electrical conductivity of each material with respect to pure copper (% IACS). The Brinell hardness was measured in accordance with GOST 23667-79 on samples before and after their annealing at 850 ± 5°C for 1 h in argon. The recrystallization temperature was determined according to ISO 5182, according to which the recrystallization temperature of materials was determined by measuring their hardness after annealing for 2 hours as the temperature at which a drop in hardness of 15% occurs. The ultimate strength in transverse bending of prismatic samples with dimensions of 9.40 _-0.36 x 9.40 _-036 x 50 mm was determined according to GOST 14019-2003 at a loading rate of 2 mm/min with a distance between two supports of 40 mm. The load was applied by a concentrated force P at the middle of the distance between the supports. Those samples that were tested at temperatures of 200 ° C and 700 ° C were first heated in special heat-saving canisters containing a charcoal carburizer to a temperature exceeding the required test temperature by 60-70 ° C before testing. The temperature was measured using a thermocouple installed in a hole in the end face of the sample. After that, the sample was quickly removed from the case, placed on a two-point support mounted on the traverse of the 1958U universal tensile testing machine, and quickly loaded with force until the sample was destroyed. The ultimate strength in bending was determined by the formula:

σ_izg = 1.5PL/b ³ ,

where P is the breaking load;

L - distance between supports;

b is the size of the cross section of the sample.

The relative volumetric electroerosive wear of the electrode tool h _v and the volumetric productivity of electroerosive machining P _v were used as operational characteristics of the materials of electrode tools, which were determined by the corresponding formulas:

h _v \u003d (Δ V _ei / Δ V _zag ) 100%,

where Δ V _ee , Δ V _zag - volumetric electroerosive wear, respectively, of the electrode-tool and the workpiece.

П _v = V _zag / τ _o = ( m _{zag o} - m _zag ) / ρ _zag τ _o ,

where ΔV _zag- the volume of material removed from the workpiece;

m _{zag about} , m _zag - the mass of the processed workpiece, respectively, in the initial state and after its processing;

τ _about - the main processing time.

Sintered hard alloy of the titanium-tungsten group of hard alloys grade T15K6 (ISO 513-75) in the form of plates with nominal dimensions of 7 × 14 × 20.5 mm was used as a difficult-to-cut material for piercing in the experiments.

The absolute density of the hard alloy, the claimed material and the prototype material was determined by calculation by weighing ground prismatic samples according to GOST 24104-2001 on electronic scales with a reading accuracy of ±0.001 g (GOST R 53228-2008).

To determine these performance characteristics, electrodes-tools were tested from the claimed material and the prototype material on a universal electroerosive copy-piercing machine model MA 4720U with a short pulse generator GKI-250 in a mixture of clarified kerosene and machine oil (1: 1). The processing was carried out with the reverse polarity of the electrodes-tools connected to a high-frequency current source with short rectangular pulses with a frequency of 88 kHz. The operating current in the interelectrode gap was 2.5A, the voltage was 65V. The duty cycle, pause, number of power units, flow rate and pressure of the working fluid were unchanged for all experiments. The depth of lowering of the spindle head with the electrode from touching the surface of the workpiece was 5 ± 0.01 mm and was controlled by the ICh50 indicator (reading accuracy ± 0.01 mm). Cleaning - washing the interelectrode space from sludge (electroerosion products) - was carried out by pumping the working fluid through a hole in the electrode-tool.

For the manufacture of electrode-tools for their testing, the obtained hot-pressed rods from the claimed material were cut into separate workpieces of electrode-tools with a length of 50 mm. All four side faces of these workpieces were flat ground to a cross-sectional size of 8.85 ^+0.1 x 8.85 ^+0.1 mm and the roughness of the machined surfaces R _a = 2.5 µm. The samples obtained from the prototype material also produced flat grinding of all four side faces to a size in section of 8.85 ^+0.1 x 8.85 ^+0.1 mm and the roughness of the machined surfaces

R _a = 2.5 µm.

площади рабочих поверхностей электродов-инструментов, в них выполняли сквозное центральной отверстие диаметром 3,0^+0,05 мм.In order to accelerate testing through the development

area of the working surfaces of the electrode-tools, they made a through central hole with a diameter of 3.0 ^+0.05 mm.

The corrosion resistance of the materials was determined by the oxidation of the surface of the electrode-tools by the gravimetric method according to Appendix A to GOST R 53803-2010. Before etching, the electrode-tools were washed in warm water (temperature not lower than 40 °C), dried, wiped dry with a rag, followed by degreasing with acetone (GOST 2768) and weighed on a high accuracy scale (GOST R 53228-2008) according to GOST 24104- 2001. Next, the tool electrodes were etched in a 10 wt % sulfuric acid solution (GOST 4204) for 15 min. The temperature of the pickling solution was from 70°C to 80°C. After etching, the tool electrodes were washed with water, dried, and weighed on the same balance. The oxidation of the surface of the electrode-tool was determined by the formula:

a = [( m _{ei o} - m _{ei k} ) / m _{ei o} )] 100% ,

where m _{ee about} - the mass of the electrode-tool before etching;

m _{ei to} - the mass of the electrode-tool after etching.

Metallographic studies of the material structure were carried out on an Altami MET 1MT microscope. The study of the fine structure of the material was performed using a JEOL JCM-6000 NeoScope II scanning electron microscope at a magnification of up to 25000 times. The surface of the object was scanned at a voltage from 5 kV to 15 kV and an electron probe diameter of about 1 μm. The phase composition of hardening particles (dispersoids) was determined on a DRON-3M diffractometer by X-ray phase analysis of anode deposits obtained by electrolytic dissolution of samples of the material under study, and interpretation of diffraction patterns taken on cobalt radiation using β-filters with Bragg-Brentano focusing.

Physico-mechanical and operational properties of the proposed material and the prototype material are given in table. 2.

From the analysis of the data in Table. 2 it follows that the composite material based on powdered copper according to the claimed invention has higher strength and performance characteristics compared to the prototype material. In particular, its hardness without annealing and after it is not less than 4 times higher than the hardness of the prototype material in the same state, and the flexural strength of the material according to the invention at normal temperature and a temperature of 200 ° C exceeds the same characteristic of the material prototype not less than 1.6 times.

table 2 Material condition Material compositions Material - prototype No. 1 No. 2 Number 3 No. 4 No. 5 No. 6 No. 7 No. 8 No. 9 Electrical conductivity (at 20 °С), % of copper electrical conductivity (% IACS) without annealing 80 79 76 79 77 74 78 76 74 81 after annealing 82 80 76 81 77 74 79 76 74 82 Hardness (at 20 °C), HB _5/750/30 without annealing 182 181 184 180 183 186 183 184 187 45 after annealing 145 147 150 146 149 152 148 150 152 35 Recrystallization temperature, °С hardness measurements -
at 20 °C 855 855 860 860 865 870 855 860 870 280 Bending strength, MPa at 20 °С 752 758 765 755 763 773 758 761 776 458 at 200 °C 453 454 464 460 450 463 454 453 462 282 at 700 °C 150 155 153 150 154 155 155 150 154 74 Oxidation of the surface of the electrode-tool, x 10 ^-2 % without annealing 0.71 0.81 0.92 0.77 0.82 0.95 0.81 0.93 0.97 1.57 Relative volumetric wear of the electrode-tool, % without annealing 24.4 25.4 29.8 26.7 29.1 34.6 27.9 31.1 36.8 54.4 Volumetric productivity of electroerosive machining, mm ³ /min without annealing 8.89 8.54 7.29 8.13 7.47 6.26 7.80 6.95 5.93 4.03

преимущество (более, чем в 2 раза) наблюдается при температуре нагрева 700 °С, что объясняется особенностью строения тонкой структуры материала по изобретению, представляющую собой, как показали проведенные исследования, медную основу (матрицу) в виде субзерен со средним размером 100 ± 20 нм и равномерно распределенными в ней частицами γ-Al₂O₃ cо средним размером 30 ± 10 нм.More

the advantage (more than 2 times) is observed at a heating temperature of 700 °C, which is explained by the peculiarity of the structure of the fine structure of the material according to the invention, which, as studies have shown, is a copper base (matrix) in the form of subgrains with an average size of 100 ± 20 nm and γ-Al ₂ O ₃ particles uniformly distributed in it with an average size of 30 ± 10 nm.

High strength, especially in bending, is also facilitated by the macrostructure of the material according to the invention, consisting of discrete microfibers parallel to each other, which were formed as a result of pulling the pellets of the briquette in the direction of pressing during its hot extrusion (Fig. 1). As is known [PISARENKO, G.S., YAKOVLEV, A.P., MATVEEV, V.V. Handbook of Strength of Materials. 2nd ed., revised. and additional Kyiv. Sciences. thought. 1988. ISBN 5-12-0002999-4. Fig. 202 on p. 273], multilayer bodies in their transverse bending have a higher bending strength than single-layer bodies.

Due to dispersion strengthening particles γ- Al ₂ O ₃ , the material according to the invention also has a high recrystallization temperature, which exceeds the recrystallization temperature of the prototype material by more than 3 times. The characteristic indicating the corrosion resistance of the compared materials turned out to be at least 1.6 times less for the material according to the claimed invention than for the prototype material, which is explained primarily by the presence of this sintered material, in contrast to the hot-extruded material according to the invention, sufficiently large residual porosity (14-16%), which contributes to an increase in the oxide component of the material.

Despite the higher (5.3-5.5%) electrical conductivity of the prototype material compared to the electrical conductivity of the material according to the invention, the electrical erosion resistance of the latter is higher compared to the electrical erosion resistance of the prototype material: the relative volumetric wear of electrodes-tools from the proposed material 1.5-2.2 times lower than the relative volumetric wear of the electrode-tools from the prototype material.

The volumetric productivity of the process of EDM when using electrodes-tools from the material according to the claimed invention is on average 1.85 times higher than the volumetric productivity when using electrodes-tools from the material of the prototype.

It is known that the main characteristics of the tool for electroerosive shaping, as follows from the above and produced on the basis of sources [ ZHURIN , A.V. Methods for calculating technological parameters and electrode-tools in electroerosive machining: diss. ... cand. tech. Sciences. Tula. Tul. state un-t. 2005. 132 p. (retrieved 2021-11-12 at http://www.dslib.net/mex-obrabotka/metody-rascheta-tehnologicheskih-parametrov-i-jelektrodov-instrumentov-pri.html) and EKATERINICHEV, A.L. Substantiation of parameters of electrode-tools and conditions of electroerosive microformation: diss. ... cand. tech. Sciences. Tula. Tul. state un-t. 2007. 142 p. (found 2021-11-12 at <http://www.dslib.net/mex-obrabotka/obosnovanie-parametrov-jelektrodov-instrumentov-i-uslovij-jelektrojerozionnogo.html>)] calculations should be:

- electrical conductivity (at 20°С), % of the electrical conductivity of copper, not less than - before annealing 73 - after annealing at 850 ± 5°С for 1 h 73 - Brinell hardness (at 20°C), HB _5/750/30 , not less than - before annealing 180 - after annealing at 850 ± 5°С for 1 h 145 - recrystallization temperature (heat resistance), °C, not less than 850 - ultimate strength in bending, MPa, not less than: - at 20°C 750 - at 200°C 450 - at 700°C 150 - oxidation of the surface of the electrode-tool with the weight method of measurement,%, no more 0.01 - relative volumetric electroerosive wear electrode-tool, %, no more thirty - volumetric productivity of electroerosive processing, mm ³ / min, not less 5

A comparison of the above characteristics of the properties of the claimed material and the parameters of its structure with those characteristics and parameters that should have been achieved in the claimed invention shows that, as a result of obtaining a balanced chemical composition and structure, the proposed composite material based on powdered copper has physical and mechanical properties. and performance characteristics that meet and exceed their required values, which means the achievement of the technical result claimed by the invention and, thus, the possibility of using a composite material based on powdered copper according to this invention for the manufacture of high-performance tool electrodes for electroerosive machining of metallic materials, predominantly hard-to-machine and, above all, for flashing deep holes and small grooves in them.

Since the requirements for electrode-tools for electroerosive flashing are in many respects similar to the requirements for electro-contact materials, and when forming the structure and studying the mechanisms of operation of materials for electrode-tools, they are guided by patterns similar to those used for electro-contact materials [OGLEZNEV, N.D. Development of composite materials for electrode-tools with improved performance for processing metal alloys: diss. …cand. tech. Sciences. Permian. Perm National research polytechnic un-t. 2015. 137 p., especially p. 25 (found 2021-11-15 at http://research.sfu-kras.ru/sites/research.sfu-kras.ru/files/Dissertaciya_Ogleznev.pdf>)], then the claimed composite material based on powdered copper can be proposed for use also as a material for resistance welding electrodes.

Claims (2)

Composite material based on powdered copper containing graphite, characterized in that it additionally contains aluminum and copper oxide in the following ratio, wt.%: Aluminum 0.81-0.95 Graphite 0.10-0.20 copper oxide 3.39-3.49 Copper rest

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