RU2367542C2 - Method of receiving of fine-dispersed metallic, alloyed and composite powders - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: inventions relate to method of receiving of metallic, alloyed and composition powders with middle size of particles D50, not exceeding 25 micrometre from initial powder with particles more than middle size. Particles of initial powder at deformation stage are processed into particles of platelet shape with ratio of diametre to thickness, located in the range from 10:1 up to 10000:1. Particles of platelet shape are subject to crush grinding at presence of grinding intensifier.

EFFECT: ability of receiving of ductil metallic powders and alloys and ability of purposeful adjustment of powders conditions.

46 cl, 7 dwg, 4 tbl, 12 ex

Description

The invention relates to a method for producing metal, alloyed or composite powders with an average particle diameter of D50 not exceeding 25 microns, and the initial powder is first converted into lamellar particles, which are then subjected to grinding in the presence of grinding intensifiers, as well as to a metal alloyed by the specified method or composite powder.

Numerous metallurgical or chemical methods for producing metal and alloyed powders are known. If it is necessary to obtain a fine powder, the initial stage of the known methods is often the melting of the corresponding metal or alloy.

When a melt is dispersed by spraying it through a nozzle, powder particles are formed directly from the droplets of the melt due to their solidification. Depending on the method of cooling the melt (air, inert gas or water), the technological parameters of spraying, for example the geometric characteristics of the nozzle, the speed and temperature of the gas or the type of material from which the nozzle is made, as well as the characteristics of the melt material, such as its melting and solidification temperature , solidification behavior, viscosity, chemical composition and reactivity with respect to process fluids, there are numerous options for implementing the spraying method through PLO, as well as restrictions for use (W.Schatt, K.-P.Wieters in "Powder Metallurgy - Processing and Materials", EPMA European Powder Metallurgy Association, 1997, 10-23).

Since obtaining powders by spraying through a nozzle is of particular technical and economic importance, various principles for its implementation have been developed. The specific spraying method is selected depending on the required properties of the obtained powder, such as particle size, particle size distribution, morphology, the presence of impurities, and also in accordance with the properties of the sprayed melts, such as melting point or reactivity, and acceptable production costs. However, there are often economic and technical limits on the justification of production costs, which make it possible to achieve a certain set of powder properties (particle size distribution, impurity content, “target grain” yield, particle morphology, their ability to sinter, etc.) (W.Schatt, K.-P.Wieters in "Powder Metallurgy - Processing and Materials", EPMA European Powder Metallurgy Association, 1997, 10-23).

The disadvantage of the method of producing powders by spraying through a nozzle is primarily the need to use large amounts of energy and atomizing gas, which makes the technology extremely expensive. In particular, it is unprofitable to obtain fine powders from refractory alloys with a melting point above 1400 ° C, because, on the one hand, the high melting temperature causes an extremely high consumption of energy needed to obtain a melt, and on the other hand, as the required particle sizes decrease gas consumption increases. In addition, difficulties often arise if at least one of the alloy elements has a high chemical affinity for oxygen. Thanks to the use of specially designed nozzles to produce alloy powders with a particularly high dispersion, it is possible to provide advantages in terms of the corresponding production costs.

Along with the production of particles by spraying through a nozzle, other one-stage pyrometallurgical technologies are also often used, for example, the so-called melt spinning, i.e., melt casting on a cooled roller, which results in the formation of a thin, usually suitable for grinding, belt or so-called crucible extraction melt, that is, the immersion of a rotating at a high speed cooled profiled roller in the molten metal, and get particles or fibers.

Another important option for the production of powders is a chemical method involving the reduction of metal oxides or salts. However, obtaining doped powders by this method is not possible (W. Schatt, K.-P. Wieters in "Powder Metallurgy - Processing and Materials", EPMA European Powder Metallurgy Association, 1997, 10-23).

An extremely fine powder with particles smaller than a micrometer can also be obtained by combining the evaporation and condensation of metals and alloys, as well as through the use of gas-phase reactions (W. Schatt, K.-P. Wieters in Powder Metallurgy - Processing and Materials ", EPMA European Powder Metallurgy Association, 1997, 39-41). However, the technical implementation of these methods is extremely expensive.

If a large volume / melt block is cooled, then to obtain metal or alloyed powders suitable for processing by powder metallurgy methods, technological operations of coarse, fine and ultrafine mechanical grinding should be used. An overview of mechanical methods for producing powders is given in W. Schatt, K.-P. Wieters in "Powder Metallurgy - Processing and Materials", EPMA European Powder Metallurgy Association, 1997, 5-47.

Mechanical grinding of materials, especially grinding in mills, is the most technically advantageous oldest method for controlling particle sizes, since this method can be implemented at low cost and is applicable for the processing of numerous materials. However, mechanical grinding requires compliance with certain requirements for the crushed material, for example, to the size of the original pieces and fragility. In addition, mechanical grinding is not always unlimited. A further reduction in particle size is hindered by the establishment of an equilibrium degree of grinding, which also occurs if the grinding process is started with finer dispersed starting powders. The traditionally used grinding processes are modified if they reach the physical limits of the ability of the starting material to grind, as well as to optimize certain effects, for example, the low-temperature transition of the material to a brittle state or the influence of grinding intensifiers on the behavior of the material during grinding, respectively, its ability to grind.

In many cases, a particularly suitable method for fine grinding relatively brittle, pre-milled materials is based on the use of gas counterflow jet mills, which can be supplied by many commercial enterprises, in particular by Hosokawa-Alpine or Netzsch-Condux. Grinding in such mills is widely used, and compared with traditionally used for purely mechanical grinding mills, such as ball mills or ball mills with agitators, jet mills provide significant technical (low impurity content, autogenous grinding) and economic advantages, especially if fragile materials are subject to grinding. Jet mills reach the limit of their technical, and therefore economic, capabilities when it comes to grinding ductile feed powders, that is, difficult to grind materials, and to the small size of the final grain. This circumstance is due to a decrease in the kinetic energy of the powder particles, grinding themselves in a gas stream. Since the powder particles are supplied with kinetic energy only from the carrier gas, the specific consumption of energy necessary for fine grinding increases to an economically unacceptable limit and becomes practically unacceptable when processing powders with increased ductility. In addition, the sinterability of powders ground by this method does not correspond to the sinterability of powder particles obtained by traditionally used grinding methods.

Extremely fine particles can be obtained, for example, by combining grinding operations with hydrogenation and dehydrogenation reactions, including combining reaction products to provide the desired phase composition of the powder (IRHarris, C. Noble, T. Bailey, Journal of the Less-Common Metals, 106 (1085, L1-L4), however, the applicability of the combined method is limited by alloys containing elements capable of forming stable hydrides. grinding effects, leading to disruption of the crystal lattice of powders or other defects.This circumstance is especially important if the functional properties of the powder particles, for example crystallinity, have a significant effect on the properties of the final powder product, for example, when it comes to permanent magnets from an alloy of neodymium, iron and boron (NdFeB).

The limit of applicability of the above methods always comes when it becomes necessary to obtain extremely fine powders of ductile metals or alloys that have both high reactivity with respect to oxygen and high sintering ability.

To obtain such products, a process was developed involving the use of refrigerants, according to which metal particles cooled to low temperatures are passed through a venturi, after which they collide with a cooled plate with an extremely high speed reaching Mach one. According to data provided by W. Schatt, K.-P. Wieters in "Powder Metallurgy - Processing and Materials", EPMA European Powder Metallurgy Association, 1997, 9-10, a powder with a particle size of 5 to 10 microns can be obtained by this method . However, the need to accelerate the original powder to sound speed determines the extremely high energy consumption used to implement this method. In addition, problems may arise due to increased abrasion, and due to the interaction of particles with the plate, hazardous impurities can get into the material being ground.

Another method for producing fine powders from ductile materials is mechanical alloying. In this case, as a result of intensive grinding, agglomerates are obtained consisting of crystallites ranging in size from 10 to 0.01 microns. Due to the influence of a powerful mechanical load, the ductile metal material changes in such a way that, under certain conditions, individual small particles are formed. These particles have a typical alloy composition. However, this method has the disadvantage of sometimes significant contamination of the crushed material with impurities, which is primarily due to abrasion. Uncontrolled abrasion, as a rule, is an obstacle to the technical use of this method. In addition, discrete small particles are formed only as a result of extremely long grinding. In this regard, it is not possible to obtain finely dispersed metal and alloyed powders by simple mechanical alloying.

Based on the foregoing, the present invention was based on the task of proposing a method for producing finely dispersed, primarily ductile metal, alloyed or composite powders, and the method should be suitable primarily for producing alloys, that is, multicomponent systems, and should provide the opportunity for targeted regulation of the most important properties of powders such as particle size, particle size distribution, sintering ability, impurity content or particle morphology, respectively enno allow for the possibility to influence these properties.

According to the invention, this problem is solved by a two-stage method, whereby the initial powder is first converted into lamellar particles, which are then crushed in the presence of grinding intensifiers.

Thus, an object of the present invention is a method for producing metal, alloy or composite powders with an average particle diameter of D50, determined according to ASTM C 1070-01 on a Microtrac ^® × 100 measuring device not exceeding 25 microns, from a starting powder with particles of a larger average diameter, moreover

a) the particles of the initial powder at the stage of deformation are processed into particles of a plate shape with a ratio of diameter to thickness ranging from 10: 1 to 10000: 1, and

b) lamellar particles are subjected to grinding milling in the presence of a grinding enhancer.

A Microtrac ^® × 100 particle size meter can be purchased from Honeywell (USA).

The diameter and thickness of the plate-shaped particles in order to subsequently determine their ratio is measured by optical microscopy. To do this, first, two volume parts of a viscous transparent epoxy resin are mixed with one volume part of lamellar particles. Then from the resulting mixture by vacuum remove air bubbles that got into it with stirring. The mixture freed from air bubbles is poured onto a flat substrate and rolled out over its entire width with a roller. Due to this, the lamellar particles acquire a preferred orientation in the flow field between the roller and the substrate. Preferred is the orientation of the lamellar particles, according to which the normal to the surface of the particles on average are parallel to the normal to the surface of the smooth substrate, that is, the particles of lamellar shape are arranged in layers on average plane parallel to the substrate. After curing the epoxy, samples of the proper size are cut from the wafer formed on the surface of the substrate. These samples are examined under a microscope in the directions perpendicular and parallel to the substrate. When using a microscope equipped with calibrated optics and observing a fairly accurate particle orientation, determine the sizes of at least fifty particles and calculate the corresponding average value. This average value corresponds to the diameter of the lamellar particles. Then the test sample is cut in the direction perpendicular to the substrate and the thickness of the plate-shaped particles is determined under a microscope with calibrated optics, which was used to measure the diameter. Particular attention should be paid to the fact that particles located as plane-parallel as possible relative to the substrate are subjected to measurement. Since the particles are placed in a transparent epoxy resin shell surrounding them on all sides, it is not difficult to select properly oriented particles and reliably correlate the contours observed under the microscope with the particles to be evaluated. The thickness of at least fifty particles is determined in the above manner and the corresponding average value is calculated. This average value corresponds to the thickness of the lamellar particles. Using the mean diameters and thicknesses of lamellar particles measured above, the ratio of these parameters is calculated.

Proposed in the invention method, first of all can be obtained finely dispersed ductile metal, alloyed or composite powders. In this case, ductile metal, alloyed or composite powders are understood to mean powders which, under the influence of a mechanical load, undergo plastic elongation or deformation until a yield point is reached, before a characteristic damage to the material occurs (its transition to a brittle state, fracture). Such plastic changes in a material depend on its properties, and they correspond to an interval from 0.1% to several hundred percent based on the initial length.

The degree of ductility, that is, the ability of materials to undergo plastic, that is, residual deformation under the action of mechanical stress, can be determined, respectively described, by mechanical tensile and / or compression tests.

To determine the degree of ductility by means of a mechanical tensile test, samples of the test material, the so-called tensile test specimens, are made. In this case, we can talk about samples having, for example, a cylindrical shape, the middle part of which is a length of about 30-50% of the total length of the sample, has a diameter reduced by about 30-50%. The tensile test specimen is fixed in the clamping device of an electromechanical or electro-hydraulic machine designed for tensile testing. Before starting a direct mechanical test, a sensitive element of the length sensor is attached to the middle part of the sample, the measuring base of which is about 10% of the total length of the sample. In the process of applying mechanical tensile stress, this sensitive element allows you to track the increase in the length of the selected measuring base. The voltage is increased until it destroys the sample, after which, based on a graphical record of the dependence of elongation on stress, the numerical value of the fraction of plastic strain in the total change in the length of the sample is determined. Materials whose plastic strain rate established in the test is at least 0.1% are considered ductile in the context of the present invention.

Similarly, on a standard compression test machine, a cylindrical sample of material with a diameter to thickness ratio of about 3: 1 can also be subjected to mechanical loading by compression. In this case, sufficient mechanical loading by compression also leads to the appearance of permanent deformation of the cylindrical sample. After removing the compressive load and extracting the sample, an increase in the ratio of its diameter to thickness is determined. Materials whose plastic strain rate established in the test is at least 0.1% are considered ductile in the context of the present invention.

Proposed in the invention method, it is preferable to obtain finely divided ductile doped powders, the degree of ductility of which is at least 5%.

According to the invention, the suitability for grinding by themselves incapable of further grinding of alloyed or metal powders is enhanced by the use of grinding intensifiers of mechanical, mechanochemical and / or chemical action, which are added purposefully or which are created during the grinding process. One of the most important aspects of this approach is the inadmissibility of changing the total specified chemical composition of the powder obtained using grinding intensifiers, or even exerting such an effect on the powder that would lead to an improvement in its technological properties, for example, increase the ability of the powder to sinter, or flow.

The method of the invention is suitable for producing various finely divided metal, alloyed or composite powders with an average particle diameter of D50 not exceeding 25 microns.

So, for example, can be obtained metal, alloyed or composite powders, the composition of which corresponds to the formula

wherein

And means one or more of the following elements: iron (Fe), cobalt (Co), nickel (Ni),

B means one or more of the following elements: vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), manganese (Mn), rhenium (Re), titanium ( Ti), silicon (Si), germanium (Ge), beryllium (Be), gold (Au), silver (Ag), ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium ( Ir), platinum (Pt),

C means one or more of the following elements: magnesium (Mg), aluminum (Al), tin (Sn), copper (Cu), zinc (Zn), and

D means one or more of the following elements: zirconium (Zr), hafnium (Hf), rare earth metal, and

h, i, j and k mean mass contents, and

h, i, j and k, respectively, independently from each other mean contents from 0 to 100 wt.%,

provided that the sum of h, i, j and k is 100 wt.%.

In the formula (I)

And preferably means one or more of the following elements: iron (Fe), cobalt (Co), nickel (Ni),

In preferably means one or more of the following elements: vanadium (V), chromium (Cr), molybdenum (Mo), tungsten (W), titanium (Ti),

C preferably means one or more of the following elements: magnesium (Mg), aluminum (Al), and

D preferably means one or more of the following elements: zirconium (Zr), hafnium (Hf), yttrium (Y), lanthanum (La).

h is preferably from 50 to 80 wt.%, particularly preferably from 60 to 80 wt.%,

i preferably ranges from 15 to 40 wt.%, particularly preferably from 18 to 40 wt.%,

j preferably ranges from 0 to 15 wt.%, particularly preferably from 5 to 10 wt.%,

k is preferably from 0 to 5 wt.%, particularly preferably from 0 to 2 wt.%.

The metal, alloy or composite powders obtained according to the invention are composed of particles having a small average diameter D50. The average particle diameter D50 determined according to ASTM C 1070-01 on a Microtrac ^® × 100 measuring device is preferably not more than 15 μm.

As starting powders can be used, for example, powders that already have the necessary composition of the final metal, alloy or composite powders. However, in accordance with the method of the invention, it is also possible to use a mixture of several starting powders, the desired composition of the final metal, alloy or composite powders being provided only by choosing the appropriate ratio between the starting powders. In addition, the choice of grinding intensifier may also have an effect on the composition of the final metal, alloy or composite powder if it remains in the final product.

The starting powders are preferably powders with a spherical or angular particle shape and ASTM C 1070-01 defined average particle diameter D50 of more than 25 μm, preferably in the range from 30 to 2000 μm, particularly preferably from 30 to 1000 μm.

The necessary starting powders can be obtained, for example, by spraying molten metals through a nozzle and, if necessary, subsequent air classification or sieving.

According to the invention, the starting powder is first processed in the deformation step. The deformation step can be carried out in a known device, for example, a roll crusher, a Gametag mill, a high-energy mill or an abrasor, respectively a ball mill with a stirrer. Due to the selection of appropriate technological parameters, primarily due to the action of mechanical stresses sufficient to ensure plastic deformation of the material, respectively, of the powder particles, individual particles are deformed in such a way that ultimately they take the form of plates, the thickness of which is preferably from 1 to 20 μm. Such deformation can be realized, for example, by exposure to single loads in a roller or hammer mill, repeated exposure to loads during short-term deformation operations, for example, by impact grinding in a Gametag mill or Simoloyer ^® mill, or by combining impact and friction grinding, for example in an eraser or ball mill. A high load on the material during such plastic deformation can cause a violation of its crystalline structure and / or transition of the material to a brittle state, which can be used for grinding it in subsequent technological stages.

In addition, known pyrometallurgical methods of accelerated solidification can be used with the aim of manufacturing ribbons or so-called flocken. The latter are also suitable for the subsequent grinding grinding described below, as well as plate-shaped particles obtained by mechanical methods.

The devices used for the deformation stage, grinding means and other grinding conditions are preferably chosen so that the impurity content due to abrasion and / or interaction with oxygen or nitrogen is as low as possible and is below the applicability threshold of the final product, respectively, within the corresponding material specifications.

This can be achieved, for example, by the proper selection of the material from which the grinding tank is made and the material from which the grinding tool is made, the use of gases that prevent the oxidation and formation of metal nitrides, and / or the addition of protective solvents during the deformation step.

According to one particular embodiment of the method according to the invention, lamellar particles are obtained at the quick solidification stage, which is realized, for example, by the so-called melt spinning, that is, obtained directly from the melt by cooling it on one or more, preferably cooled rolls, or between rolls, due to which there is a direct formation of plates (flocken).

According to the invention, the lamellar particles obtained in the deformation step are subjected to grinding milling. In this case, firstly, the ratio between the particle diameter and thickness changes, and, as a rule, primary particles with a diameter to thickness ratio of 1: 1 to 10: 1 are obtained. Secondly, regulate the required average particle diameter of not more than 25 microns, without the formation of agglomerates of particles, which are difficult to regrind.

Grinding grinding can be performed, for example, in a mill, in particular an eccentric mill, as well as in a Gulbett mill, designed for hot pressing by a press or similar devices, causing a violation of the ordering of the material of the plate particles, due to different speeds of its movement and loading.

According to the invention, grinding grinding is carried out in the presence of a grinding intensifier. As grinding enhancers, for example, liquid grinding enhancers, waxes and / or brittle powders can be added. In this case, grinding intensifiers can have a mechanical, chemical or mechanochemical effect.

Grinding enhancers are, for example, paraffin oil, paraffin wax, metal powder, alloy powder, metal sulfides, metal salts, organic acid salts and / or high-strength material powder.

Brittle powders or phases act like mechanical grinding intensifiers and can be used, for example, in the form of powders from alloys, elements, high-strength materials, carbides, silicides, oxides, borides, nitrides or salts. So, for example, pre-ground element powders and / or doped powders are used, which together with the hard-to-grind source powder used, form a final powder having the necessary composition.

As brittle powders, binary, ternary and / or consisting of a greater number of elements of the composition are preferably formed by the elements A, B, C and / or D present in the starting alloy used, wherein A, B, C and D are as described above.

Can also be used liquid and / or easily deformable intensifiers grinding, for example wax. Suitable examples are hydrocarbons such as hexane, as well as alcohols, amines or aqueous media. In this case, it is preferably about compounds that may be necessary for subsequent technological operations and / or can be easily removed at the end of grinding milling.

Special organic compounds known from the field of pigment production can also be used, where they are used to stabilize non-forming agglomerates of individual lamellar particles in a liquid medium.

According to one particular embodiment of the invention, grinding intensifiers are used that enter into targeted chemical interaction with the starting powder to ensure successful grinding and / or establishment of a specific chemical composition of the final product. This may involve, for example, degradable chemical compounds, only one or several components of which are necessary to ensure the required composition of the final product, and at least one component, respectively one component, can be removed as completely as possible by implementing a thermal process.

Examples of such chemical compounds are reducible and / or destructible substances, such as hydrides, oxides, sulfides, salts, sugars, which, during subsequent technological operations and / or during the pyrometallurgical processing of the powder product, are at least partially removed from the crushed material, the remaining part performs the function of an additive providing the required chemical composition of the final powder.

In addition, you can not add a grinding intensifier specifically, but get it in the process of grinding grinding in situ. This may involve, for example, the generation of a grinding intensifier due to the addition of a chemically active gas, which under certain conditions of grinding grinding interacts with the initial powder, forming a brittle phase. Hydrogen is preferably used as the reactive gas.

The brittle phases created by treatment with a chemically active gas, for example, phases formed by hydrides and / or oxides, can be removed after a successful grinding grinding, as a rule, during an appropriate technological operation or during further processing of the obtained finely dispersed metal, alloyed or composite powder.

Grinding enhancers that are not removed from the metal, alloyed or composite powders obtained according to the invention or only partially removed, are preferably selected so that the remaining components have the desired effect on a particular property of the material, for example, improve its mechanical properties, reduce the susceptibility to corrosion, increased hardness and improved abrasive properties, respectively, frictional and antifriction characteristics. An example of such a grinding intensifier is a high-strength material, the content of which at a subsequent technological stage is increased so that this high-strength material can be further processed together with the alloyed component into a hard alloy, respectively, a composite material consisting of a high-strength material and an alloyed component.

According to the invention, the average diameter D50 determined by ASTM C 1070-01 on a Microtrac ^® × 100 device of the primary particles of a metal, alloy or composite powder obtained as a result of the deformation stage and subsequent grinding grinding does not exceed 25 microns.

The known interactions between the particles of ultrafine powder despite the use of grinding intensifiers, along with the desired formation of small primary particles, can lead to the formation of larger secondary particles (agglomerates), the diameter of which significantly exceeds the required average particle diameter of not more than 25 microns.

In this regard, after grinding grinding, a deagglomeration step is preferably carried out, which ensures the destruction of the agglomerates and the release of primary particles. Deagglomeration can be carried out, for example, by applying shearing forces in the form of mechanical and / or thermal loads and / or by removing the separation layers previously introduced between the primary particles. The deagglomeration methods used in special cases are implemented taking into account the degree of agglomeration of the primary particles, the purpose of the final fine powder, its tendency to oxidize, and the allowable content of impurities in the finished product.

Deagglomeration of the powder can be carried out, for example, by mechanical methods, in particular by treatment in a gas countercurrent jet mill, sieving, air classification or processing in an eraser, mixer or disperser of the rotor-stator type. In addition, stress fields similar to those generated by ultrasonic treatment, heat treatment, for example, release under the influence of low or high temperatures, respectively, conversion of a separation layer previously introduced between primary particles, or chemical conversion of introduced or purposefully created phases can be used for this purpose.

Deagglomeration is preferably carried out in the presence of one or more liquids, auxiliary dispersants and / or binders. A similar method can be used to obtain a slip, paste, plasticine or suspension with a solids content of from 1 to 95 wt.%. If the solids content in such compositions is in the range from 30 to 95 wt.%, They can be directly processed by methods adopted in powder technology, for example by injection molding, film casting, layering, hot casting, and then turned into the final product by carrying out drying, binder and sintering operations.

For deagglomeration of powders particularly sensitive to the effects of oxygen, a gas countercurrent jet mill is preferably used, which operates using an inert gas such as argon or nitrogen.

The metal, alloyed or composite powders obtained by the method of the invention, as compared to conventional powders obtained, for example, by spraying through a nozzle, particles of which have a similar average diameter and similar chemical composition, have a number of specific properties.

Thus, another object of the present invention is a metal, alloy and composite powders with an average particle diameter of D50, determined according to ASTM C 1070-01 on a Microtrac ^® × 100 device, not exceeding 25 microns, which can be obtained by the method proposed in the invention.

Thus, for example, the metal, alloy and composite powders according to the invention have excellent sintering properties. A sintering density similar to the sintering density of powders obtained by spraying through a nozzle can be achieved at a lower temperature. From pressed blanks having a certain pressing density, at the same sintering temperature, products with a higher density can be obtained. The increased sintering ability of the powders according to the invention is manifested, for example, also in that the shrinkage during sintering up to its maximum value exceeds the shrinkage that occurs during sintering of powders obtained by the traditional method.

Thus, another object of the present invention are metal, alloy or composite powders with a certain

ASTM C 1070-01 on a Microtrac ^® × 100 instrument with an average particle diameter of D50 not exceeding 25 μm, and the shrinkage determined by the dilatometer according to DIN 51045-1, up to reaching its maximum value, is at least 1.05 from the shrinkage obtained by spraying through a nozzle a metal, alloy or composite powder of the same chemical composition and with a similar average particle diameter D50, moreover, the powder to be tested is densified before shrinkage measurement to a pressing density of 50% of theory optical density.

In this case, the test powder can be densified by adding conventional compressive agents, for example paraffin wax, other waxes, salts or organic acids, for example zinc stearate.

By spraying obtained metal, alloyed or composite powders, in comparison with which the powders according to the invention have an improved sintering ability, we mean powders obtained by the conventionally used, well-known specialists method of spraying through a nozzle.

The preferred ability to sinter proposed in the invention of metal, alloyed and composite powders clearly demonstrate the curves of sintering, respectively, shrinkage, shown as an example in Fig.7.

Figure 7 shows the shrinkage (S), respectively, the shrinkage rate (AS), the comparative powder (V) and the inventive powder (PZD), respectively, in relative units, depending on the temperature T _N normalized to the corresponding sintering temperature T _S.

Comparative powder (V) means a product obtained by spraying in an inert atmosphere through a nozzle, the composition of which and the particle morphology correspond to the material described in Example 1. The size distribution of particles (their D50 is about 8.4 microns) is similar to that shown in Figure 5. By the powder of the invention (PZD) is meant a powder obtained in accordance with Example 1, which has the particle morphology shown in FIG. 6 and contains 0.4% by weight of oxygen.

After mixing each of the powders with 3 wt.% Microwax, used as a pressing aid, by pressing them in a press die with a force of 400-600 MPa, pressed blanks are made. The density of freshly prepared blanks in both cases is about 40% of the theoretical density. Each of the obtained pressed blanks is sintered in a dilatometer according to DIN 51045-1, using argon as a protective process gas. Heating is carried out at a speed of about 1 K / min (respectively, about 6 · 10 ^-4 · T _s / min, while T _s is about 1600 K). The sensitive plug of the dilatometer does not exert any pressure on the sample; in the sintering temperature region of interest (0.5 to 0.95 T _S ), the plunger makes a measurable contribution to the shrinkage achieved during sintering.

When the temperature rises to 0.45 * T _S , the organic additive facilitating pressing is displaced. With the continuation of heating carried out at a constant rate in the temperature range from 0.5 to 0.99 T _S , direct sintering occurs with the formation of solids.

The advantages of the powder according to the invention are ensured by the following effects and general patterns resulting from the consideration of FIG. 7. To understand them, we should first introduce the notation used for the general description of sintering processes:

Proposed in the invention powders have the following General properties compared with a powder obtained by the traditional method of spraying through a nozzle:

( ^PZD T _max - ^PZD T ₁₀ ) / ^PZD T _max > ( ^V T _max - ^V T ₁₀ ) / ^V T _max (I) ^PZD T _max < ^V T ^max (Ii) ^PZD T ₁₀ < ^V T ₁₀ (III) ^PZD T ₁ < ^V T ₁ (Iv) ^PZD S _max < ^V s _max (V) ( ^PZD T _max - ^PZD T ₁₀ ) > ( ^V T _max - ^V T ₁₀ ) (Vi) ( ^PZD T _max - ^PZD T ₁ ) > ( ^V T _max - ^V T ₁ ) (Vii) ( ^PZD T ₉₀ - ^PZD T ₁₀ ) > ( ^V T ₉₀ - ^V T ₁₀ ) (Viii) ( ^PZD T ₉₀ - ^PZD T ₁ ) > ( ^V T ₉₀ - ^V T ₁ ) (Ix)

Based on the above inequalities, the following conclusions can be made regarding the difference in the properties of the powder of the invention (PZD) and the comparative powder (V) obtained by the conventional nozzle spraying method.

- The powder according to the invention has a wider sintering temperature range.

- The powder according to the invention has a lower shrinkage start temperature, at which it is 10% of the same final shrinkage for both powders, and a lower temperature, at which the shrinkage reaches its maximum value.

- From a consideration of the maximum shrinkage rates in the corresponding normalized dependencies shown in Fig.7, it follows that the powder according to the invention has a lower shrinkage rate at ^PZD T _max than the comparative sample at ^V T _max .

- The powder according to the invention has a wider initial temperature range until maximum shrinkage is achieved.

- The powder according to the invention has a wider interval between the temperature of the start of shrinkage and the temperature of reaching its maximum value.

- The powder according to the invention has a wider interval between a temperature corresponding to a shrink of 10% and a temperature corresponding to a shrink of 90%.

- The powder according to the invention has a wider interval between the temperature of the start of shrinkage and the temperature corresponding to shrinkage of 90% of its final value.

These findings relate to the single-phase initial state of the powders. In the presence of other phases, the entire set of inequalities (I) - (IX) must not always be observed: in particular, in pressed blanks made from the powders proposed in the invention, very high rates of local shrinkage can be observed due to increased activation of sintering of the liquid phases, which is an additional advantage of such powders in terms of technological properties. However, the validity of inequalities (III), (IV), (VIII) and (IX) remains unshakable in this case too.

In addition, the metal, alloyed and composite powders according to the invention, due to the special morphology of the particles with a rough surface that form them, are characterized by high compressibility and high density resulting from compaction, due to the relatively wide particle size distribution. This is manifested in the fact that, ceteris paribus, the pressed billets from powders obtained by spraying through a nozzle have a lower bending strength than the pressed billets from the powders of the invention of a similar chemical composition with a similar average particle size D50. An additional improvement in the properties of pressed blanks can be achieved by using powder mixtures containing from 1 to 95 wt.% Of the metal, alloy or composite powder according to the invention and from 99 to 5 wt.% Of powder obtained by spraying through a nozzle.

In addition, a targeted effect on the sintering ability of the powders according to the invention can be achieved by choosing the proper grinding intensifier. So, for example, one or several alloys can be used as a grinding intensifier, which, due to the lower melting temperature compared to the initial alloy, form liquid phases during heating, which improve the mutual arrangement of particles, as well as the diffusion of materials, and therefore, sintering shrink properties, respectively, due to which, at a similar temperature, higher sintering densities can be achieved, or a sintering density similar to that of comparative sintering oshkov can be achieved at a lower temperature of the process. Chemically degradable compounds can also be used, the degradation products of which, together with the base material, form liquid phases or phases with increased diffusion coefficients that have a beneficial effect on compaction.

According to the results of X-ray diffraction studies, reflections expanded in comparison with powders obtained by spraying through a nozzle and having a similar average particle diameter and similar chemical composition are found on the diffraction patterns of the metal, alloyed and composite powders of the invention. The expansion of x-ray reflexes is manifested in an increase in the corresponding half-width values. The half-width of X-ray reflexes of the powders of the invention, as a rule, increases by more than 1.05 times. The reason for this phenomenon is the mechanically stressed state of the particles, the presence of a higher concentration of dislocation, that is, atomic defects of a solid, and the size of crystallites present in the particles. In the case of composite powders, along with extended x-ray reflections of the main phase, the phases determined by the presence of alloys and / or technological reasons and of great importance for shrinkage properties are found in the corresponding diffraction patterns.

Proposed in the invention method allows to obtain metal, alloyed and composite powders with purposefully controlled content of oxygen, nitrogen, carbon, boron and silicon. In the presence of oxygen or nitrogen, the use of an increased amount of energy can contribute to the formation of oxide and / or nitride phases. The presence of such phases may be desirable for certain areas of use of the finished powders, since it is able to provide hardening of the material. A similar phenomenon is known and is called the dispersion gain effect of particles. However, the presence of such phases is often responsible for the deterioration of the technological properties of powders (for example, a decrease in their ability to compact and sinter). Due to the fact that the dispersed phases are, as a rule, inert with respect to alloys, they can have a sintering effect.

The grinding milling carried out according to the invention provides an immediate ultrafine distribution of the above phases in the resulting powder. Therefore, the phases formed in the metal, alloyed and composite powders proposed in the invention (for example, the phases of oxides, nitrides, carbides, borides) are distributed in them much finer and more uniformly than in the powders obtained by the traditional method. This, in turn, leads to an increased ability to sinter compared with the introduction of similar discrete phases.

The technological properties of the metal, alloyed and composite powders proposed in the invention, for example, the ability to compaction and sintering, as well as the suitability for processing by casting metal powders under pressure, slip method or the method of casting films, can often be further improved by admixing metal, alloyed and composite powders obtained by traditional methods, primarily by spraying through a nozzle.

Thus, another object of the present invention are mixtures containing from 1 to 95 wt.% Proposed in the invention of a metal, alloyed or composite powder and from 99 to 5 wt.% Obtained by the usual method of a metal, alloy or composite powder.

The inventive mixtures preferably contain from 10 to 70 wt.% Proposed in the invention of a metal, alloyed or composite powder and from 90 to 30 wt.% Metal, alloyed or composite powder obtained in the usual way.

By a conventional method, a metal, alloy or composite powder is preferably a powder obtained by spraying through a nozzle.

The metal, alloy or composite powder obtained by the usual method may have the same chemical composition as the powder of the invention mixed with it. The corresponding mixtures, in comparison with the pure powders of the invention, are distinguished primarily by their further improved compressibility.

However, it is also possible different chemical composition proposed in the invention powder and powder obtained by the usual method, forming the appropriate mixture. In this case, one can purposefully vary the composition of the mixture and thereby purposefully control certain properties of the powder, and therefore the properties of the material.

Below the invention is considered in more detail by examples of its implementation, which serve to understand the principle underlying the invention, and do not limit its scope.

The values of the average particle diameter D50 given in the examples were determined according to ASTM C 1070-01 on a Microtrac ^® × 100 measuring device from Honeywell (USA).

Example 1

The starting powder used atomised through the nozzle via argon alloy powder Nimonic ^® type 90, having the composition Ni20Cr16Co2,5Ti1,5Al. The resulting powder was sieved, taking fractions with a particle size in the range from 53 to 25 μm. The density of the powder was about 8.2 g / cm ³ . As shown in FIG. 1, the particles of the initial powder had a predominantly spherical shape (the image was obtained with a scanning electron microscope at 300 × magnification).

The initial powder was subjected to strain milling in a vertical ball mill with a stirrer (Netzsch Feinmahltechnik, type PR 1S), as a result of which the particles of the initial spherical shape took the form of plates. Used, in particular, the following grinding parameters:

Figure 2 shows a snapshot obtained after the implementation of the stage of deformation of lamellar particles (scanning electron microscope, 300-fold increase). The shape of the particles as a result of special processing has undergone significant changes compared to the original powder. The image also shows defects in the structure of the material (cracking).

Next, the powder was subjected to grinding grinding. For this purpose, an eccentric vibration mill (Siebtechnik GmbH, ESM 324) and the following process parameters were used:

As a result of a two-hour grinding grinding, agglomerates formed by small primary particles were obtained. Figure 3 shows a snapshot of the product obtained in a scanning electron microscope at 1000x magnification. The image shows agglomerates (secondary particles) with a structure resembling cauliflower, and the diameter of the primary particles is much less than 25 microns.

To obtain individual primary particles, a sample of primary particles, respectively, agglomerates consisting of them, was deagglomerated for 10 minutes by ultrasonic treatment in a TG 400 ultrasonic device (Sonic Ultraschallanlagenbau GmbH) in an isopropanol medium at a load of 50 for 10 minutes % of the maximum power of the device.

The particle size distribution of the deagglomerated sample was determined according to ASTM C 1070-01 on a Microtrac ^® × 100 instrument (manufactured by Honeywell, USA). The particle size distribution curve shown in FIG. 4 was obtained. The D50 of the starting powder was 40 μm, and after the treatment according to the invention was carried out, it decreased to about 15 μm.

The remaining amount of the primary particles obtained in the grinding milling stage in the alternative third technological stage was subjected to deagglomeration, carried out by treatment in a gas countercurrent jet mill and subsequent ultrasonic treatment in isopropanol medium in a TG 400 ultrasonic device (Sonic Ultraschallanlagenbau GmbH) with a load of 50% of maximum power of the device. Particle size was also determined on a Microtrac ^® × 100 instrument. The obtained particle size distribution curve is shown in FIG. 5. The D50 after deagglomeration did not exceed 8.4 microns. This confirms the possibility of further increasing the content of fine particles by additional high-energy processing of the powder obtained according to the invention.

Obtained in a scanning electron microscope image of particles subjected to processing in a gas countercurrent jet mill, is shown in Fig.6 (600-fold increase). By using the proper air classification method, it is possible to obtain doped powders having an even narrower particle size distribution. Thus, it is technically feasible to produce particles with a D50 of less than about 8 microns.

Paraffin introduced as a grinding intensifier can be removed by thermal degradation and / or evaporation during further processing of the alloyed powder by powder metallurgy methods, and accordingly, it can be used as an auxiliary substance in subsequent pressing.

Example 2

Obtaining ultrafine Fe24Cr10Al1Y powders using a mechanical grinding intensifier without changing the composition of the initial powder

500 g of the initial alloyed powder Fe24Cr10Al1Y, spherical particles of which had an average diameter (D50) of 40 μm, under conditions similar to Example 1, were processed into a powder with plate-shaped particles.

Then, grinding of lamellar particles was carried out in an eccentric vibration mill, as described in Example 1. In this case, a mixture of crushed brittle powders Fe70Cr, Fe60Al and Fe16Y with an average particle diameter of about 40 μm and finely divided iron (Fe) powder with an average diameter were added as a grinding intensifier D50 particles of 10 μm.

For grinding grinding used 15 g of intensifier grinding. Typical for this stage is the addition of about 10 vol.% With a mechanical effect of the intensifier grinding. Depending on the goal, it may be appropriate to add smaller amounts of grinding intensifiers. The composition of the grinding intensifier used is presented in Table 1. A mixture is formed containing 65 wt.% Iron (Fe), 24 wt.% Chromium (Cr), 10 wt.% Aluminum (Al) and 1 wt.% Yttrium (Y). Thus, due to the choice of the amounts of alloys forming the grinding intensifier indicated in Table 1, the chemical composition of the initial powder does not change. The composite powder obtained by the method proposed in the invention has a special distribution of the components used for its preparation (initial powder, grinding intensifier), due to which, during the further processing of this powder, carried out, for example, by sintering, or other heat treatment, it undergoes a metallurgical change .

Table 1.
The composition of the mechanical intensifier grinding Component Amount [g] Iron (Fe) [g] Chromium (Cr) [g] Aluminum (Al) [g] Yttrium (Y) [g] Fe 16 Y 0.93 0.78 0 0 0.15 Fe 60 Al 2,50 1,0 0 1,5 0 Fe 70 Cr 5.14 1,54 3.6 0 0 Iron (Fe) 6.43 6.43 0 0 0 Amount fifteen 9.75 3.6 1,5 0.15

After grinding grinding and deagglomeration performed in an ultrasonic field, a composite powder was obtained with an average particle diameter D50 of 15 μm. After further heat treatment, a metallurgical alloy can be obtained from such a composite powder.

Example 3

Obtaining ultrafine Fe24Cr10Al1Y powders using a mechanical grinding intensifier and a change in composition compared to the initial powder

In contrast to Example 2, in this case, sought to change the chemical composition in the grinding process, respectively, its change was permissible. Obtained by spraying Fe25,6Cr10,67Al doped powder with an average particle diameter of D50 of 40 μm, was subjected to deformation under conditions similar to those described in Example 1. Received plate-shaped particles with an average diameter of D50 of 70 μm, which looked mostly also as in Example 1.

Then the lamellar particles were subjected to grinding milling. It was carried out similarly to Example 1, however, 10 g of Fe16Y powder with an average particle diameter of D50 of 40 μm was used as a grinding intensifier, and the grinding time was 2 hours.

Table 2 shows the composition and amount of the initial alloyed powder with plate particles and the alloy added as an intensifier of grinding grinding.

Table 2.
The composition of the initial alloyed powder with plate particles and the used mechanical grinding intensifier Component Amount [g] Iron (Fe) [g] Chromium (Cr) [g] Aluminum (Al) [g] Yttrium (Y) [r] Fe25.6Cr10.67Al 150 95.6 38,4 16,0 0 Fe16y 10 8.4 0 0 1,6 Amount 160 104 38,4 16,0 1,6

As follows from the data in Table 2, the resulting composite powder obtained as a result of grinding grinding had the composition Fe24Cr10Al1Y. He was subjected to ultrasound treatment, which resulted in a composite powder with an average particle diameter of D50 of 13 μm.

Example 4

The example was carried out similarly to Example 3, however, as a grinding intensifier, a mixture of several brittle materials and pure iron powder were used.

Table 3 shows the composition and weight of the original powder and intensifier grinding. The brittle grinding intensifiers Fe60Al, Fe70Cr and Y2.2H were subjected to grinding at a separate grinding stage before use to obtain particles with an average diameter of D50 of 40 μm. The average particle diameter of the used iron (Fe) D50 powder was 10 μm.

Table 3.
The composition of the initial alloyed powder with plate particles and the used mechanical grinding intensifier Component Amount [g] Iron (Fe) [r] Chromium (Cr) [g] Aluminum (Al) [g] Yttrium (Y) [g] Fe25.6Cr10.67Al 150.00 95.60 38.40 16.00 0.00 Fe60Al 1.19 0.48 0.00 0.71 0.00 Fe70Cr 2,35 0.71 1,64 0.00 0.00 Y2.2 H 1,66 0.00 0.00 0.00 1,66 Iron (Fe) 10.00 10.00 0.00 0.00 0.00 Amount 165.20 106.79 40.04 16.71 1,66

As follows from the data in Table 3, the resulting composite powder obtained by grinding grinding had the composition Fe24Cr10Al1Y. He was subjected to ultrasound treatment, which resulted in a composite powder with an average particle diameter of D50 of 15 μm.

Example 5

Obtaining ultrafine powder Fe24Cr10Al1Y from two powders of an alloy of iron, chromium and aluminum (FeCrAl) and Fe16Y as the only brittle mechanical grinding intensifier

Each of the two obtained by spraying through a nozzle doped powders of the composition Fe19.9Cr24.8Al, respectively Fe27.9Cr5Al, with an average particle diameter of D50 of 40 μm, was processed similarly to Example 1 at separately realized stages of deformation, obtaining lamellar particles with an average diameter of D50 of 70 μm, the appearance of which basically did not differ from the particles shown in Figure 2.

In the subsequent grinding grinding, the powder of a particularly brittle alloy Fe16Y, previously ground to particles with an average diameter of D50 of about 40 μm, was used as the only grinding intensifier. Grinding grinding was carried out similarly to Example 1, and its duration was 2.5 hours.

Table 4 shows the composition and weights of both initial doped FeCrAl powders with lamellar particles and a brittle grinding intensifier Fe16Y.

Table 4.
The composition of the initial alloyed powders with lamellar particles and the used mechanical grinding intensifier Component Amount [g] Iron (Fe) [g] Chromium (Cr) [g] Aluminum (Al) [g] Yttrium (Y) [g] Fe19.9Cr24.8Al 43 23.8 8.6 10.5 0 Fe27.9Cr5Al 107 71.8 29.8 5.5 0 Fe16y 10 8.4 0 0 1,6 Amount 160 104 38,4 16 1,6

As follows from the data in Table 4, the resulting composite powder obtained by grinding grinding had the composition Fe24Cr10Al1Y. He was subjected to ultrasound treatment, which resulted in a composite powder with an average particle diameter of D50 of 12 μm.

Example 6

The preparation of the intensifier grinding in situ

Obtained by spraying a doped powder of the composition Ni15Co10Cr5.5Al4.8Ti3Mo1V, commercially available under the trade name IN 100 ^® , was subjected to deformation carried out in an inert atmosphere, as described in Example 1.

During the subsequent grinding grinding, a brittle grinding intensifier was not added, however, it was formed during the grinding process in situ. To this end, an eccentric vibratory mill was filled with a gas mixture containing 94 vol.% Argon and 6 vol.% Hydrogen. In this case, the working volume of the mill was thermally insulated so that the process temperature was set at about 300 ° C due to the thermal energy released during grinding. The remaining grinding conditions corresponded to those indicated in Example 1. The increased temperature and the presence of hydrogen in the process gas provided the formation of brittle compounds of titanium with hydrogen (Ti-H), as well as vanadium with hydrogen (VH), the effect of which was similar to that used in examples 1-5 intensifiers grinding and, therefore, contributed to grinding. As a result of a three-hour grinding in an atmosphere containing hydrogen, a doped powder was obtained with an average particle diameter of D50 of 13 μm.

The resulting ultrafine powder in its chemical composition only slightly differed from the original powder. The hydrogen content increased, amounting to less than 1000 ppm. During the subsequent processing of the doped powder obtained in accordance with the invention by sintering in vacuum, the hydrogen content again decreased and amounted to less than 50 ppm.

Example 7

Silicon (Si) powder as grinding intensifier

Obtained by spraying through a nozzle, doped Ni38Cr8.7Al1.09Hf powder with an average spherical particle diameter of D50 of 40 μm was subjected to processing at the deformation stage, as described in Example 1.

150 g of a plate-shaped powder obtained in an abrasive was subjected to grinding in an eccentric vibration mill, as described in Example 1, and 13 g of silicon (Si) powder with an average particle diameter of D50 of 40 μm was used as a grinding intensifier. As a result of a two-hour grinding, a doped powder of the required composition (Ni35Cr8Al8Si1Hf) with an average particle diameter of D50 of 10.5 μm was obtained. The use of silicon is desirable, respectively, necessary to obtain an alloy of the desired composition. Of the possible brittle grinding intensifiers, silicon is particularly suitable due to its inherent properties. The oxygen content in the treated powder was about 0.4 wt.%.

Example 8

The sprayed doped Ni38Cr8.7Al1.09Hf powder with an average spherical particle diameter of D50 of 40 μm was processed at the deformation stage as described in Example 7 using an eraser (ball mill with a stirrer).

Subsequent grinding grinding was also carried out in a ball mill with a stirrer in the presence of 13 g of silicon powder (Si) used as grinding intensifier with the following technological parameters:

Upon completion of the 1.5-hour grinding milling and subsequent ultrasonic deagglomeration, a doped powder was obtained with an average particle diameter of D50 of 13 μm (Microtrac ^® × 100 measuring instrument). In this case, the use of silicon is desirable, respectively, necessary to establish the required final composition of Ni35Cr8Al8Si1Hf, and from a technological point of view, silicon is selected to provide the necessary grinding efficiency. Of the elements used as grinding intensifiers, silicon is best suited due to its inherent fragility. Grinding grinding led to an increase in the oxygen content in the powder. At the end of the grinding, it was 0.4 wt.%.

Example 9

Obtained by spraying through a nozzle a doped powder of composition Ni17Mo15Cr6Fe5W1Co with an average spherical particle diameter of D50 of 40 μm, commercially available under the trade name Hastelloy ^® C, was subjected to deformation, as described in Example 1.

Next, a powder with plate-shaped particles was subjected to grinding grinding in an eccentric vibration mill in the presence of tungsten carbide (WC) grinding used as an intensifier under the following conditions:

As a result of grinding grinding, a composite powder was obtained consisting of an alloy and a high-strength material, the average diameter D50 of the alloy particles being about 5 μm and the average diameter D50 of particles of high-strength material being about 1 μm. Particles of high strength material were predominantly evenly distributed in the bulk of the alloyed powder.

A composite powder consisting of an alloy and a high-strength material could be processed into a powder suitable for spray application in the usual way. To this end, to 163 g of the composite powder made of the alloy and high-strength material obtained by the method of the invention, 797 g of tungsten carbide with an average particle size of ASTM B 330 (FSSS) of 1 μm, ethanol, polyvinyl alcohol and suspension stabilizers were added to dispersing and obtaining a suspension. A suspension was obtained containing up to 25 vol% of the metal binder phase and up to 75 vol% of the high-strength material phase formed by tungsten carbide. This suspension was further processed by spray granulation and air classification to obtain a spray product with particles ranging in size from 20 to 63 microns. Organic auxiliary substances were first removed from this semi-finished product by passing gas at a temperature of from 100 to 400 ° C, after which sintering was performed in an inert atmosphere at a temperature of about 1300 ° C. In this case, strong bonds between the granules and less strong bonds between the individual granule grains arose. In conclusion, deagglomeration and air classification were carried out, obtaining a fraction with the necessary grain sizes (for example, from 15 to 45 μm). The obtained powder can be used for the manufacture of parts coated with solid metal, respectively, of a composite consisting of an alloy and high strength material, by means of known thermal spraying methods.

Example 10

Titanium powder with an average particle diameter of D50 of 100 μm was processed according to the invention according to the method similar to Example 1.

The obtained powder was subjected to further processing by grinding grinding similarly to Example 1, with 10 g of titanium hydride TiH _{2 being} added to a sample of plate-shaped particles of titanium (150 g). As a result of grinding grinding, finely dispersed titanium powder with an average particle diameter of D50 of about 15 μm was obtained.

The titanium powder obtained by the method of the invention can be processed into molded products using conventional technology. The resulting titanium powder was protected from oxidation by storing it under a layer of an organic solvent, for example n-hescan. Before further metallurgical processing, long chain hydrocarbons, such as paraffin, or amines, were added to the titanium powder. To this end, paraffin was dissolved, for example, in n-hexane, the solution was added to the powder, and then n-hexane was removed by evaporation with continuous stirring of the powder. This ensured encapsulation of the particle surface, which prevented uncontrolled absorption of oxygen and improved the ability of the powder to be processed by compression. Thanks to this, it was possible to process titanium powder in air.

After uniaxial pressing of the powder into molded products by heat treatment, the organic components were removed, thermal degradation of the grinding intensifiers was thermally degraded, as well as high density sintering into the molded products.

Example 11

Lamellar particles of doped 17-4 PH ^® powder (Fe17Cr12Ni4Cu2.5Mo0.3Nb), obtained analogously to Example 1, were processed in a countercurrent mill. The ratio of the diameter of the lamellar particles to the thickness was about 1000: 1 with an average diameter D50 of 150 μm. The powder was treated in a countercurrent mill in an inert gas atmosphere. As a grinding intensifier, we used non-pretreated material made from a similar alloy with spherical particles with a diameter of 100 to 63 μm obtained by spraying through a nozzle. A working tank with a capacity of about 5 l was filled with 2.5 l of powder (bulk volume) containing 67 wt.% Grinding intensifier and 33 wt.% Plate-shaped particles and started grinding. Sifting of the obtained fine fraction was carried out by appropriate adjustment of the air classifier (for a particle size of 10 μm) connected in series to the mill.

Unlike the previous examples, due to the technology described above, grinding grinding and, in most cases, the necessary deagglomeration was carried out in one stage. A feature of this technology was the use of a similar doped powder or a similar grinding intensifier in the form of an unmilled or poorly ground powder, which during the grinding process provided more intensive energy transfer and, consequently, increased grinding effect.

Example 12

Obtained by spraying a nozzle doped Ni17Mo15Cr6Fe5W1Co powder with a particle diameter of 100 to 63 μm, commercially available under the trade name Hastelloy ^® C, was machined in a high-energy mill (eccentric vibration mill) under the following conditions:

Received plate-shaped particles with a thickness of about 20 μm with a ratio of diameter to thickness of 1: 2.

Then, grinding milling was carried out in a gas countercurrent jet mill. During the grinding process, due to the proper adjustment of the air classifier connected in series to the mill, particles with a diameter of less than 20 μm were selected. In a similar manner, finely dispersed doped powder was obtained, the particles of which after ultrasonic treatment had an average diameter D50 of 12 μm and a D90 of 20 μm determined on a Microtrac ^® × 100 instrument.

Claims (46)

1. The method of producing metal, alloyed or composite powders with an average particle diameter of D50, determined according to ASTM C 1070-01 on a Microtrac ^® × 100 measuring device not exceeding 25 microns, from the initial powder with particles of a larger average diameter, namely, that
a) the particles of the initial powder are processed at the stage of deformation into lamellar particles with a ratio of diameter to thickness ranging from 10: 1 to 10000: 1, and
b) lamellar particles are subjected to grinding milling in the presence of a grinding enhancer. 2. The method according to claim 1, in which after grinding grinding carry out the stage of deagglomeration. 3. The method according to claim 1, in which the composition of the metal, alloy or composite powder corresponds to the formula (I)

in which A means one or more of the elements: iron (Fe), cobalt (Co), nickel (Ni),
B means one or more of the elements: vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), manganese (Mn), rhenium (Re), titanium ( Ti), silicon (Si), germanium (Ge), beryllium (Be), gold (Au), silver (Ag), ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium ( Ir), platinum (Pt),
C means one or more of the elements: magnesium (Mg), aluminum (Al), tin (Sn), copper (Cu), zinc (Zn), and
D means one or more of the elements: zirconium (Zr), hafnium (Hf), rare earth metal, and
h, i, j and k mean mass contents, and
h, i, j and k, respectively, independently from each other mean contents from 0 to 100 wt.%,
provided that the sum of h, i, j and k is 100 wt.%. 4. The method according to claim 3, in which
And means one or more of the elements: iron (Fe), cobalt (Co), nickel (Ni),
B means one or more of the elements: vanadium (V), chromium (Cr), molybdenum (Mo), tungsten (W), titanium (Ti),
C means one or more of the elements: magnesium (Mg), aluminum (Al), and
D means one or more of the elements: zirconium (Zr), hafnium (Hf), yttrium (Y), lanthanum (La). 5. The method according to claim 3, in which
h is from 50 to 80 wt.%,
i is from 15 to 40 wt.%,
j is from 0 to 15 wt.%,
k is from 0 to 5 wt.%
provided that the sum of h, i, j and k is 100 wt.%. 6. The method according to claim 4, in which
h leaves from 50 to 80 wt.%,
i is from 15 to 40 wt.%,
j is from 0 to 15 wt.%,
k is from 0 to 5 wt.%
provided that the sum of h, i, j and k is 100 wt.%. 7. The method according to one of claims 1 to 6, in which the average particle diameter D50 of the obtained metal, alloyed or composite powders, determined according to ASTM C 1070-01 on a Microtrac ^® × 100 device, does not exceed 15 microns. 8. The method according to one of claims 1 to 6, in which the initial powder is understood to be a powder with particles of a spherical or angular shape, the average diameter of D50 of which, determined according to ASTM C 1070-01 on a Microtrac ^® × 100 device, is more than 25 microns. 9. The method according to claim 7, in which the initial powder means a powder with particles of a spherical or angular shape, the average diameter of D50 of which, determined according to ASTM C 1070-01 on a Microtrac ^® × 100 device, is more than 25 microns. 10. The method according to one of claims 1 to 6 or 9, in which the stage of deformation is carried out in a roller crusher, a Gametag mill, a high-energy mill or an abrasive. 11. The method according to claim 7, in which the stage of deformation is carried out in a roller crusher, a gametag mill, a high-energy mill or an abrasive. 12. The method according to claim 8, in which the stage of deformation is carried out in a roller crusher, a gametag mill, a high-energy mill or an abrasor. 13. The method according to one of claims 1 to 6, 9, 11 or 12, in which, when grinding grinding, liquid grinding enhancers, waxes and / or brittle powders are added as grinding intensifiers. 14. The method according to claim 7, in which, when grinding grinding, liquid grinding enhancers, waxes and / or brittle powders are added as grinding intensifiers. 15. The method according to claim 8, in which when grinding grinding as grinding intensifiers add liquid intensifiers grinding, wax and / or brittle powders. 16. The method according to claim 10, in which, when grinding grinding, liquid grinding enhancers, waxes and / or brittle powders are added as grinding intensifiers. 17. The method according to item 13, in which under the intensifier grinding refers to paraffin oil, paraffin wax, metal powder, alloy powder, metal sulfide, salt and / or powder of high strength material. 18. The method according to 14 or 15, in which under the intensifier grinding refers to paraffin oil, paraffin wax, metal powder, alloy powder, metal sulfide, salt and / or powder of high strength material. 19. The method according to clause 16, in which under the intensifier grinding refers to paraffin oil, paraffin wax, metal powder, alloy powder, metal sulfide, salt and / or powder of high strength material. 20. The method according to one of claims 1 to 6, 9, 11, 12, 14-17 or 19, in which the intensifier grinding is obtained in the process of grinding grinding in situ. 21. The method according to claim 7, in which the intensifier grinding is obtained in the process of grinding grinding in situ. 22. The method of claim 8, in which the intensifier grinding is obtained in the process of grinding grinding in situ. 23. The method according to claim 10, in which the intensifier grinding is obtained in the process of grinding grinding in situ. 24. The method according to item 13, in which the intensifier grinding is obtained in the process of grinding grinding in situ. 25. The method according to p, in which the intensifier grinding is obtained in the process of grinding grinding in situ. 26. The method according to claim 20, in which the intensifier grinding is obtained by supplying a reaction gas, which under the conditions of grinding grinding interacts with the original powder with the formation of a brittle phase. 27. The method according to one of paragraphs.21-25, in which the intensifier grinding is obtained by supplying a reaction gas, which under the conditions of grinding grinding interacts with the original powder with the formation of a brittle phase. 28. The method according to one of claims 2 to 6, 9, 11, 12, 14-17, 19 or 26, in which deagglomeration is carried out in a gas countercurrent jet mill, an ultrasonic bath, a mixer or a dispersing device of the rotor-stator type. 29. The method according to claim 7, in which the deagglomeration is carried out in a gas countercurrent jet mill, ultrasonic bath, mixer or dispersing device of the rotor-stator type. 30. The method according to claim 8, in which the deagglomeration is carried out in a gas countercurrent jet mill, ultrasonic bath, mixer or dispersing device of the rotor-stator type. 31. The method according to claim 10, in which the deagglomeration is carried out in a gas countercurrent jet mill, ultrasonic bath, mixer or dispersing device of the rotor-stator type. 32. The method according to item 13, in which the deagglomeration is carried out in a gas countercurrent jet mill, ultrasonic bath, mixer or dispersing device of the rotor-stator type. 33. The method according to p. 18, in which the deagglomeration is carried out in a gas countercurrent jet mill, ultrasonic bath, mixer or dispersing device of the rotor-stator type. 34. The method according to claim 20, in which the deagglomeration is carried out in a gas countercurrent jet mill, ultrasonic bath, mixer or dispersing device of the rotor-stator type. 35. The method according to item 27, in which the deagglomeration is carried out in a gas countercurrent jet mill, ultrasonic bath, mixer or dispersing device of the rotor-stator type. 36. The method according to one of claims 2 to 6, 9, 11, 12, 14-17, 19, 21-26 or 29-35, in which deagglomeration is carried out in the presence of one or more liquids, dispersants and / or binders. 37. The method according to claim 7, in which the deagglomeration is carried out in the presence of one or more liquids, dispersants and / or binders. 38. The method of claim 8, in which the deagglomeration is carried out in the presence of one or more liquids, dispersants and / or binders. 39. The method according to claim 10, in which the deagglomeration is carried out in the presence of one or more liquids, dispersants and / or binders. 40. The method according to item 13, in which the deagglomeration is carried out in the presence of one or more liquids, dispersants and / or binders. 41. The method according to p, in which the deagglomeration is carried out in the presence of one or more liquids, dispersants and / or binders. 42. The method according to claim 20, in which the deagglomeration is carried out in the presence of one or more liquids, dispersants and / or binders. 43. The method according to item 27, in which the deagglomeration is carried out in the presence of one or more liquids, dispersants and / or binders. 44. The method according to p, in which the deagglomeration is carried out in the presence of one or more liquids, dispersants and / or binders. 45. Metallic, alloyed or composite powder with an average particle diameter of D50 determined according to ASTM C 1070-01 on a Microtrac ^® × 100 measuring device not exceeding 25 microns, characterized in that it is obtained by the method according to claim 1 and its shrinkage, determined by means of a dilatometer according to DIN 51045-1, until its maximum value is at least 1.05 from the shrinkage obtained by spraying through a nozzle a metal, alloy or composite powder of a similar chemical composition and with a similar average particle diameter D50, wherein the powder to be tested is densified prior to shrinkage measurement to a compression density of 50% of the theoretical density. 46. A mixture containing from 1 to 95 wt.% Metal, alloyed or composite powder according to item 45 and from 99 to 5 wt.% Metallic, alloyed or composite powder obtained by spraying through a nozzle.

Images