RU2230629C2 - Metallic powders produced by reducing oxides by means of gaseous magnesium - Google Patents

Abstract

FIELD: production of metallic powders used for making electrolytic capacitors.

SUBSTANCE: method for producing metallic powder with high factor of surface area selected from tantalum, niobium and their alloys as pure powders or with use of titanium, molybdenum, tungsten, hafnium, vanadium and(or) zirconium added or produced together with above mentioned powders comprises steps of preliminary producing oxide or mixed oxides of metal(s) in the form of oxide porous mass having some shape through which gas may be passed; using as reducing agent gas generated outside porous mass; performing reduction process by passing gaseous reducing agent through said mass at elevated temperature; selecting reagents, porosity degree, temperature and time interval for realizing reaction in such a way that to provide practically complete reduction of oxide(s), separation of its metallic component and to receive oxide of reducing agent generated during said reaction and may be easily removed. According to invention niobium powder has primary agglomerated particles with size in range 100 - 1000 nm. Agglomerates have predetermined dimensions D10, D50, D90 and they contain particles respectively with fraction size in range 3 - 80 micrometers, 20 - 250 micrometers and 30 - 400 micrometers.

EFFECT: enhanced manufacturing properties of powder.

67 cl, 33 dwg, 16 tbl, 18 ex

Description

The invention relates to the field of production of electrolytic capacitors, and more particularly to a method for producing a metal powder (its variants), a niobium powder from agglomerated primary particles and a method for producing a powder containing niobium and tantalum.

A known method of producing a metal powder selected from the group consisting of tantalum, niobium and their alloy, including the restoration of the original powder with a reducing agent at a temperature below 0.7 melting point of the powder (see US patent 5242481, class. 22 F 9/20 , published on September 4, 1993)

The disadvantage of this method is that the technological properties of the obtained powder do not satisfy all the growing requirements for modern electrolytic capacitors.

Known powder from group VB in the form of agglomerated primary particles (see application WO 94/25971, CL H 01 G 9/05, publ. 10.11.1994)

A disadvantage of the known powder is that the technological properties of the obtained powder do not satisfy all the growing requirements for modern electrolytic capacitors.

A known method for the production of tantalum powder, including hydrogenation of an ingot of an electron beam melting alloy, grinding a hydrogenated alloy ingot, dehydrogenation of a crushed alloy, molding the crushed alloy into flakes, agglomeration of the obtained alloy flakes in the presence of an alkaline earth metal as a reducing agent, leaching and washing of agglomerated flakes alloy to remove any residues and residual product of a reducing agent (see application WO 93/03191, CL 22 C 1/04, H 01 G 9/05, publ. 18. 02.1993 g.)

The disadvantage of this method is that the technological properties of the obtained powder do not satisfy all the growing requirements for modern electrolytic capacitors.

The objective of the invention is to improve the technological properties of metal powder.

The problem is solved in a method for producing a metal powder selected from the group consisting of tantalum and / or niobium and their alloy, including reduction due to the fact that the oxide or mixture of oxides of the obtained metal (s) is preliminarily obtained in the form of an oxide porous mass having the form through which the gas can be passed, a gas containing hydrogen is passed through the oxide porous mass at an elevated temperature, and the oxide porosity, temperature and reduction reaction time are selected so that pour at least 20% of the oxygen contained in the oxide to produce suboxide and further reduction of the suboxide in the second stage with reducing agents selected from the group of reducing metals and hydrides of reducing metals, for almost complete reduction of the oxide with the release of its metal part, this produces a powder selected from the group consisting of tantalum and / or niobium and their alloy, in pure form or with one or more metals selected from the group consisting of titanium, molybdenum, in lframa, hafnium, vanadium and zirconium are added to or received together with them.

In addition, the problem is solved by the proposed niobium powder in the form of agglomerated primary particles due to the fact that the size of the primary particles is from 100 to 1000 nm, and the agglomerates have a particle size of D10, D50 and, accordingly, D90 determined from ASTM B822, ranging from 3 to 80 microns, from 20 to 250 microns and, accordingly, from 30 to 400 microns.

The preferred sizes of D10, D50 and D90, respectively, of the agglomerates are 3-7 μm, 70-250 μm, in particular 130-180 μm and 230-400 μm, in particular 280-350 μm, respectively.

In addition, the problem is also solved in a method for producing a powder, including hydrogenation of an electron beam smelting alloy ingot, grinding the hydrogenated alloy ingot, dehydrogenating the milled alloy, molding the milled alloy into flakes, agglomeration of the obtained alloy flakes in the presence of an alkaline earth metal as a reducing agent , leaching and washing agglomerated alloy flakes to remove any residues and residual product of the reducing agent due to that they produce niobium powder in the form of agglomerated primary particles, in which the primary particle size is from 100 to 1000 nm, and the agglomerates have a particle size of D10, D50, and accordingly D90, from 3 to 80 μm, from 20 to 20, according to ASTM B822 250 microns and, accordingly, from 30 to 400 microns, while it additionally contains up to 40 at.% Tantalum in relation to the total content of niobium and tantalum.

When carrying out the reduction in both variants of the proposed method, a reducing agent is preferably used selected from the group consisting of magnesium, calcium, aluminum, lithium, barium, strontium and their hydrides. The vapor pressure of some of the reducing agents is given in the following tables:

The reduction temperature varies greatly depending on the reducing agent used. The temperature range for the reduction of oxide (Ta, Mb) is as follows: with Mg _(gas) - 800-1100 ° С, Al _(gas) - 1100-1500 ° С, Li _(gas) - 100-1400 ° С, Ва _(gas) -1300-1900 ° C.

Preferably, the reduction temperature is below 0.5 TM, in particular below 0.4 TM, where TM is the melting point of the metal powder.

Various physical properties, as well as the morphology of metal powders obtained by reduction, can be achieved by changing the temperature and other process conditions within the range of values for effective recovery.

Preferred reducing agents used in the reduction method of the first embodiment and the second reduction step in the method of the second embodiment are Mg, Ca and / or their hydrides. Mg is particularly preferred.

The reduction temperature is preferably (for Mg) between 850 ° C and normal boiling point (1150 ° C).

The reduction of oxides with gaseous reducing agents, at least during the initial stage of reduction, makes it easy to control the temperature during the reaction to avoid excessive preliminary sintering. In controlled reduction with gaseous reducing metals, there is practically no contamination of the reduced metal with the reducing metal by its inclusion in the lattice of the reduced metal. It was found that such pollution mainly occurs only during the initial reduction (for Nb) of Nb ₂ O ₅ to NbO ₂ . This is surprising at first glance, since niobium suboxide (NbO ₂ ) contains only 20% less oxygen than niobium pentoxide (NbO _2.5 ). This effect can be attributed to the fact that the suboxide forms significantly denser crystals compared to pentoxide. The density of NbO _2.5 is 4.47 g / cm ³ , while the density of NbO ₂ is 7.28 g / cm ³ , i.e. the density increases 1.6 times when only 20% oxygen is removed. Given the different atomic weights of niobium and oxygen, a 42% reduction in volume is associated with the reduction of NbO _2.5 to NbO ₂ . The above effect can be explained by the fact that during the reduction of magnesium pentoxide in contact with the oxide, the latter can relatively easily diffuse into the lattice, where it has high mobility, while the mobility of magnesium in the suboxide lattice is significantly reduced. Therefore, during the reduction of the suboxide, magnesium essentially remains on the surface and is readily available for contact with washing acids.

This effect occurs even with controlled reduction with gaseous magnesium. Obviously, in this case, reduction occurs during a critical initial reduction to suboxide only on the oxide surface, and the magnesium oxide formed during reduction does not penetrate the oxide or suboxide powder. The preferred temperature during the reduction with gaseous magnesium is from 900 to 1100 ° C, particularly preferably from 900 to 1000 ° C.

The temperature can be raised up to 1200 ° C after at least 20% of the oxygen has been removed to facilitate pre-sintering.

The reduction of pentoxide with hydrogen gives a suboxide that is already sintered to form agglomerates containing stable sintered bridging bonds that have a favorable structure for use as a material for a capacitor.

Lower temperatures cause longer periods of time for recovery. Moreover, the degree of sintering of the obtained metal powders can be controlled by a predetermined method by selecting the reduction temperature and recovery time. The reactors are preferably lined with molybdenum or ceramic plates that are not reduced with H ₂ in order to prevent contamination.

Moreover, the reduction time and reduction temperature should be chosen so as to remove at least 20% of the oxygen from the pentoxide. Higher degrees of recovery are not harmful. However, it is usually not possible to recover more than 60% of oxygen within a feasible time frame and acceptable temperature.

After 20% or more reduction is achieved, suboxide is formed. According to this variant of the method, the reduction product is preferably left to stand (after annealing) for some time, more preferably for 60 to 360 minutes, at a temperature above 1000 ° C. It seems that such standing provides the formation and stabilization of a new, dense, crystalline structure. Since the reduction rate decreases significantly along with the degree of reduction, it is sufficient to heat the suboxide at a reduction temperature in a hydrogen atmosphere, optionally with a slight decrease in temperature. The recovery and annealing time from 2 to 6 hours at a temperature of from 1100 to 1500 ° C is usually sufficient. Moreover, hydrogen reduction has the advantage that the proportion of impurities, such as F, Cl and C, which are critical for use in capacitors, is reduced to less than 10 ppm, preferably to less than 2 ppm.

The suboxide is then cooled to room temperature (<100 ° C.) in a reduction apparatus, the suboxide powder is mixed with finely divided powders of reducing metals or metal hydrides, and the mixture is heated in an inert gas atmosphere to a second stage reduction temperature. Reducing metals or metal hydrides are preferably used in a stoichiometric amount with respect to the residual oxygen of an acidic alkaline earth metal suboxide and, more preferably, are used in an amount that slightly exceeds the stoichiometric amount.

One of the most preferred forms of the invention involves the use of a stirred bed in the first stage and the second stage, without intermediate cooling, in the same reactor, introducing reducing metals or metal hydrides into it. If magnesium is used as the reducing agent, it is preferably introduced into the reactor in the form of gaseous magnesium, since the metal powder formation reaction can be easily controlled.

After the reduction of the metal is completed in both methods, the metal is cooled and the inert gas is passed sequentially through the reactor with a gradual increase in the oxygen content to deactivate the metal powder. Reducing metal oxides are removed by a method known in the art by washing with acids.

Tantalum and niobium pentoxides are preferably used in the form of finely divided powders. The size of the primary grains of the pentoxide powders should approximately correspond to the 2- or 3-fold size of the primary grains of the metal powders that are obtained. The pentoxide particles preferably consist of free-flowing agglomerates with an average particle size of from 20 to 1000 nm, preferring a narrower range of particle sizes, most preferably from 50 to 300 nm.

The reduction of niobium oxide with gaseous reducing agents can be carried out in a stirred or fixed bed, such as a rotary kiln, a fluidized bed, a suspended kiln or in a small-sized tunnel hearth furnace. If a fixed layer is used, the depth of the layer should not exceed 5-15 cm so that the reducing gas can penetrate through the layer. Larger layer thicknesses may be possible if a layer nozzle is used through which gas is passed from below. For tantalum, the preferred equipment is described in Example 2 and the paragraph between Examples 2 and 3 below, with reference to FIGS. 1-4.

Preferably, the niobium powder according to this invention contains oxygen in an amount of from 2500 to 4500 ppm (hereinafter: “ppm”) / m ^{2 of} surface and otherwise having a low oxygen content, up to 10,000 ppm of nitrogen and up to 150 ppm of carbon and, not taking into account the content of alloying metals, it has a maximum content of 350 ppm of other metals, where other metals are mainly a reducing metal or a metal hydrogenation catalyst. The total content of other metals is not more than 100 ppm. The total content of F, Cl, S is less than 10 ppm.

Capacitors can be obtained from niobium powders, which are preferred according to this invention, immediately after decontamination and sieving through sieves with a hole size of 400 microns. After sintering at a density of compressed material of 3.5 g / cm ³ at a temperature of 1100 ° C and molding at 40 V, these capacitors have a specific capacitance of 80,000 to 250,000 μFV / g (measured in phosphoric acid) and a specific leakage current density of less than 2 nA / μFV. After sintering at a temperature of 1150 ° C and molding at 40 V, the specific capacitance is from 40,000 to 150,000 μFV / g and the specific leakage current density is less than 1 nA / μFV. After sintering at a temperature of 1250 ° C and molding at 40 V, capacitors are obtained that have a specific capacitance (measured in phosphoric acid) of 30,000 to 80,000 μFV / g and a specific leakage current density of less than 1 nA / μFV.

The niobium powder preferably has a specific BET surface of 1.5 to 30 m ² / g, in particular 2 to 10 m ² / g.

Using simple linear interpolation, it was found that capacitors from Nb / Ta alloy powders have significantly higher capacitance values than capacitors made from pure Nb or pure Ta powders, or expected for an alloy. The capacitances (μFV) of capacitors with sintered anodes of Nb powder and sintered anodes of Ta powder having the same surface area are approximately equal. The reason is that the higher dielectric constant of the insulated niobium oxide layer (41 compared to 26 tantalum oxide) is compensated by the greater thickness of the oxide layer per volt (anode voltage) formed during anodization. The oxide layer per volt Nb is almost twice as thick as the thickness formed on Ta (about 1.8 nm / V for Ta and about 3.75 nm / V for Nb). This invention provides capacitance with respect to the area (μFV / m ² ) of alloy powder-based capacitors up to 1.5-1.7 times higher than the expected value for linear interpolation between Nb powder-based capacitors and Nb-based capacitors Ta powder. This means that the thickness of the oxide layer per volt of the anode voltage of the alloy powders of the present invention is closer to this indicator Ta, while the dielectric constant of the oxide layer is closer to this indicator Nb. The aforementioned unexpectedly high capacitance of the alloy may be due to different structural forms of the oxide of the alloy components compared to the structure of the oxides on the surfaces of pure Nb powders. In fact, preliminary measurements showed that an increase in the oxide layer of 15 at.% Ta - 85 at.% Nb alloy is almost 2.75 nm / V.

The Ta content in the proposed powder is at least 2 at.% Tantalum, particularly preferably at least 5 at.% Tantalum, in particular 12 at.% Tantalum, relative to the total content of Nb and Ta.

Preferably, the tantalum content of the alloy powders of the present invention is less than 34 at.% Tantalum. The effect of increasing capacitance is achieved by gradually increasing the ratio of Nb to Ta atoms to about 3. More than 25 at.% Of Ta with respect to the total content of Nb and Ta increases the effect only to a small extent.

The alloy powders of the present invention preferably have a surface multiplied by BET alloy density of from 8 to 250 (m ² / g) × (g / cm ³ ), particularly preferably from 15 to 80 (m ² / g) × (g / cm ³ ). The density of the alloy can be calculated from the corresponding atomic ratio of Nb and Ta multiplied by the densities of Nb and Ta, respectively.

The effect of increasing the capacitance when producing the alloy is not limited to powders having the structure of agglomerated spherical particles. Therefore, the powder alloys of the present invention can have agglomerated flakes morphology, preferably having a product of BET surface and density from 8 to 45 (m ² / g) × (g / cm ³ ).

Particularly preferred alloy powders are agglomerates of substantially spherical primary particles having a product of BET surface and density from 15 to 60 (m ² / g) × (g / cm ³ ). The primary alloy powders (particles) may have an average diameter of from 10 to 1500 nm, preferably from 100 to 300 nm. The preferred deviation of the diameter of the primary particles from the average diameter is less than a factor of 2 in both directions.

Agglomerated powders can have the same average particle size as defined by ASTM-B 822 as the size described above for niobium powders.

Particularly preferred alloy powders have a Scott density to alloy density ratio of 0.09 to 0.18 (g / cm ³ ) / (g / cm ³ ), in particular 0.09-0.14 (g / cm ³ ) / ( g / cm ³ ).

According to the invention, a precursor is used to obtain the powder used for the capacitors, which is a precursor alloy containing niobium and tantalum in an approximately atomic ratio of Nb to Ta, preferably in an alloy metal powder, instead of a precursor containing only one tantalum.

Useful alloy precursors can be prepared by co-precipitating (Nb, Ta) compounds from aqueous solutions containing water-soluble Nb and Ta compounds, for example by co-precipitating (Nb, Ta) -oxyhydrate from an aqueous solution of heptafluoro complexes by adding ammonia and then calcining the oxyhydrate to oxide.

Particularly preferred Nb-Ta alloy powders having a morphology of agglomerated spherical particles are prepared from mixed (Nb-Ta) oxides by reduction with a gaseous reducing agent as described above.

The metal powder according to the invention can be used not only in electronic capacitors, but also in other fields, including, for example, the preparation of a complex of electro-optical, superconducting and other metals and ceramic compounds, such as PMN structures, and high-temperature modifications of metals and oxides.

The use of a capacitor may be accompanied by other known modifications of producing capacitors, such as alloying agents to slow down compaction during sintering or any other improvement in the capacitance of the final product, leakage current, and electrical breakdown.

The invention is further illustrated by the following examples, in which there is a link to Fig.1-16. Wherein

1-4 are schematic drawings of processing equipment used in the practice of this invention;

on figa-12C presents micrographs obtained by scanning electron microscope (SEM) of the powders obtained according to this invention, including some SEM examples of the prior art or comparative examples of metal powders obtained by methods other than the method of the present invention;

13 and 14 are flowcharts illustrating the diverse uses of powder and derivatives;

on Fig shows a schematic representation of the final product in accordance with the use as a capacitor (one of several forms of capacitors);

on Fig presents the curves of capacitance and surface area of powders of Ta-Nb alloy relative to the composition of the alloy.

Example 1 (comparative)

A mixture of Ta ₂ O ₅ and magnesium is loaded onto a tantalum plate and covered with a tantalum foil. Magnesium stoichiometry is 109% of what is required for the complete reduction of tantalum oxide. The mixture is heated to a temperature of 1000 ° C for 6 hours in an argon atmosphere. The mixture is not stirred during the reduction reaction. After cooling, the products are passivated with the programmed addition of oxygen. The result of the reduction reaction is a black spongy material that is difficult to break. The product is leached with dilute mineral acid to remove magnesium oxide, dried and sieved. The yield of large (+40 mesh) material is high, up to 25%. The content of each impurity (in% or ppm) and surface area (PP, cm ² / g) +40 and -40 fractions are given in table. 1.1 below. The content of both magnesium and oxygen is high. A large percentage of large material and poor product quality make it inapplicable for use in capacitors.

Example 2

1, a layer (3) of 200 g of tantalum pentoxide is placed on a porous tantalum plate 4 suspended above the shavings of magnesium metal (5) contained in a tantalum boat. The container is closed with a tantalum lid and placed in a sealed retort with argon (Ar) passed through a sealed vessel through openings (6). The boat is heated to a temperature of 1000 ° C and kept at the same temperature for 6 hours in an atmosphere of argon / gaseous magnesium using a layer (5) of solid magnesium chips, located in the part of the vessel completely separated from the oxide layer. After cooling to room temperature, the product mixture is passivated by feeding argon-oxygen mixtures containing 2, 4, 8, 15 inches (5.08, 10.16, 20.32, 38.1 cm) (mercury, partial pressure ) O ₂ (g), respectively, in the oven. Each mixture is in contact with the powder for 30 minutes. The exposure time for the last passivation by air is 60 minutes.

Magnesium oxide is separated from the tantalum powder by leaching with dilute sulfuric acid and then rinsing with high purity water to remove acid residues. The product is a free-flowing powder. Product samples (designated as Ta GR-2D) are shown in micrographs taken with a scanning electron microscope (SEM) in FIGS. 5A, 5B, 5C at 15700, 30900 and 60300 magnification, respectively, obtained with an electron microscope operating at 15 kV. A comparative example is given in FIGS. 5D and 5E, which are 70,000 times (x) SEM of tantalum powder obtained by sodium reduction. The properties of the tantalum powders shown in Fig.5A, 5B, 5C are given in table. 2.1 below.

The ratio of oxygen concentration to surface area corresponds only to the oxygen area, which means the complete reduction of tantalum oxide.

Reactor shapes alternative to that shown in FIG. 1 (and described in Example 2) are shown in FIGS. 2-4. Figure 2 shows a suspension calcination reactor 20 with a vertical pipe surrounded by a heating element 24, a source of metal oxide feedstock 25, a source of a reducing agent 26 (e.g. Mg) in the form of steam (mixed with argon), an outlet for argon 26 'and a collecting device 28 for the metal and oxide of the reducing agent. Valves V1 and V2 are also available. The oxide particles fall through the pipe and are restored by calcination in suspension. Figure 3 shows a rotary kiln 30 with an inclined rotary tube 32, a heating element 34, a loading funnel with oxide 35, a gas source (reducing agent and diluent, such as argon) and an outlet 36, 36 'and a collecting device 38 for metal and oxide reducing agent. Figure 4 shows a multi-hearth furnace 40 with a retort 42, containing rotating plates 43 and blades with keyways, a heating element 44, an oxide source 45, a gas source and an outlet 46, 46 'and a collecting device 48. Other possible shapes may be used. reactors, such as reactors with a fluidized bed furnace usually used on their own or reactors of the Contop, KIVCET types.

Example 3

A tantalum powder with a surface area of 57,000 cm ² / g, obtained according to the procedure of Example 2, is deoxygenated by mixing the powder with 2 vol / vol% Mg and heating at 850 ° C for 2 hours in an argon atmosphere. The separation of the source of the reducing agent and the oxide in this case is not necessary at this subsequent stage of deoxygenation. The deoxygenated powder is cooled and then passivated, leached and dried. SEM (100,000 magnification) of deoxygenated (final) powder is shown in Fig. 7A and SEM (70,000 magnification) of the sodium-reduced final powder is shown in Fig. 7B. The difference in morphology is obvious. After doping with 100 ppm P by adding an appropriate amount of NH ₄ H ₂ PO _{4, the} powder is pressed into pellets weighing 0.14 g at a compression density of 5.0 g / cm ³ . The SEM of the additional deoxygenated powder is shown in FIG. 6. The granules are sintered in vacuum at a temperature of 1200 ° C for 20 minutes The granules are anodized up to 30 V in 0.1 vol.% (Vol / vol%) solution of H ₃ PO ₄ at a temperature of 80 ° C. The current density during molding is 100 mA / g and the dwell time at molding voltage is 2 hours. The average capacitance of the anodized granules is 105,000 μF (V) / g and the leakage current measured after 5 minutes of applying 21 V is 0.1 nA / μF (V).

Example 4

A powder with a surface area of 133,000 cm ² / g and a bulk density of 27.3 g / m ³ obtained according to the procedure of Example 2 is processed according to the procedure of Example 3. SEM (magnification 56600) of the final powder is shown in FIG. 7C. The granules obtained from the deoxygenated powder are anodized up to 16 V using the conditions of Example 3. The average capacitance of the anodized granules is 160,000 μF (V) / g.

Example 5

900 g of Ta ₂ O ₅ restore gaseous magnesium at a temperature of 900 ° C for 2 hours. Magnesium oxide is removed from the reduction product by leaching with dilute sulfuric acid. The resulting powder has a surface area of 70,000 cm ² / g and is deoxygenated at a temperature of 850 ° C. for 2 hours using 8 vol / vol% magnesium. One (1.0) v / v% NH ₄ Cl is added to the tantalum nitriding charge. The deoxygenated powder is treated according to the procedure of Example 3. The doping level P is 200 ppm. The powder is again deoxygenated using the same time and temperature, 2.0 vol / vol% Mg and without NH ₄ Cl. Residual magnesium and magnesium oxide are removed by leaching with dilute mineral acid. The chemical properties of the powder are given in table. 5.1 below. The powder has a surface area of 9000 cm ² / g and excellent flowability. The compressed granules are sintered at a temperature of 1350 ° C for 20 minutes and anodized to 16 V in 0.1 vol / vol% H ₃ PO ₄ at a temperature of 80 ° C.

The capacitance of the anodized granules is 27500 μF (V) / g and the leakage current is 0.43 nA / μF (V).

Example 6

500 g of Ta ₂ O _{5 is} reduced at a temperature of 1000 ° C for 6 hours with gaseous magnesium. The properties of the primary powder thus obtained are given in table 6.1 below.

The primary powder is deoxygenated at a temperature of 850 ° C for 2 hours. 4 v / v% Mg and 1 v / v% NH ₄ Cl are added. MgO is leached with mineral acid. The powder is then alloyed at 200 ppm P by adding an equivalent amount of NH ₄ H ₂ PO ₄ . The powder is deoxygenated a second time at a temperature of 850 ° C for 2 hours and then nitrided at a temperature of 325 ° C by adding a gaseous mixture containing 80% argon and 20% nitrogen. Some properties of the final powder are shown in table. 6.2 below.

Granules are obtained from powder at a pressure density of 5.0 g / cm ³ . Sintered granules are anodized at a temperature of 80 ° C to 16 V in 0.1 vol / vol% solution of H ₃ PO ₄ . Capacitance and leakage currents depending on temperature are given in table. 6.3 below.

Example 7 (comparative)

Potassium heptafluoroniobate (K ₂ NbF ₇ ) is reduced with sodium using a molten salt treatment technique in a stirred reactor such as that described by Hellier et al. and Hildteth et al. U.S. Patent 5,442,978. The diluted salt is sodium chloride and the reactor is made of Inconel alloy. The niobium metal powder is separated from the salt matrix by leaching with diluted nitric acid (HNO ₃ ) and then washing with water. The individual physical and chemical properties are shown in table. 7.1 below. Very high concentrations of metal elements, nickel, iron and chromium, make the powders inapplicable for use as a material suitable for use in capacitors. Such contamination is the result of the inherent corrosive nature of K ₂ NbF ₇ . This property makes the sodium reduction method inapplicable for producing niobium powders suitable for use in capacitors.

Example 8

200 g of niobium pentoxide are reduced according to the procedure of Example 2. The resulting product is a free-flowing black powder and has a surface area of 200800 cm ² / g. The passivated product is leached with a dilute solution of nitric acid to remove magnesium oxide and residual magnesium, and then washed with high purity water to remove residual acid. This material is mixed with ten (10.0) v / v% Mg and deoxygenated at 850 ° C. for 2 hours. Physical and chemical properties of the powder are shown in table. 8.1 below. The powder was doped with 100 ppm P according to the procedure of Example 3.

SEM (magnification 70,000) are shown in FIGS. 8A and 8B, respectively, for niobium powders obtained by reduction with liquid sodium (Example 7) and gaseous magnesium (Example 8). It is noteworthy that the clustering of small particles in the form of outgrowths on large particles is much more clearly visible in Fig. 8B than in Fig. 8A. 8C and 8D show SEM (magnification 2000), respectively, of niobium powder obtained by reduction with sodium and reduction with gaseous magnesium.

The niobium powder obtained by liquid sodium reduction has large (> 700 nm) combined (300 nm +) precipitating grains and external faces that give the product a block shape, and finely divided material grains (about 10 nm, but some reach 75 nm) in the form growths, while niobium powder obtained by reduction with gaseous magnesium has a major grain size of about 400 nm and smaller grains with a diameter of about 20 nm on them, and many of these small grains themselves are agglomerates of size flesh to 100 nm.

Example 9

Granules weighing 0.14 g are obtained from the niobium powder obtained in Example 8. The granules are anodized in 0.1 vol / vol% H ₃ PO ₄ solution at a temperature of 80 ° C. The current density is 100 mA / g and the dwell time at molding voltage is 2 hours. The electrical results with respect to pellet compaction density, molding stress and sintering temperature are shown in table. 9.1 below.

Example 10

Niobium oxide is reduced with gaseous magnesium according to the procedure of Example 8. The resulting powder is subjected to deoxygenation twice. During the first deoxygenation, 2.0 v / v% NH ₄ Cl is added to the charge to nitrate the powder. Deoxygenation conditions include treatment at 850 ° C. for 2 hours with 7.0 v / v% Mg. After leaching and drying, the powder is doped with 200 ppm R. The second deoxygenation is carried out at a temperature of 850 ° C for 2 hours, using 2.5 vol / vol% Mg. The final powder has a surface area of 22,000 cm ² / g and good flowability. Chemical properties are given in table. 10.1 below. The granules are anodized up to 16 V in a 0.1 vol / vol% solution of H ₃ PO ₄ at a temperature of 80 ° C using a current density of 100 mA / g and a two-hour exposure. Electrical properties are given in table. 10.2 below.

Example 11

a) Used Nb ₂ O ₃ has a particle size of 1.7 μm, determined using the Fisher classifier (hereinafter: "FSSS" = Fisher Sub Sieve Sizer) and contains the following impurity fractions:

Total amount (Na, K, Ca, Mg) 11 ppm

Total amount (Al, Co, Cr,

Cu, Fe, Ga, Mn, Mo, Ni, Pb,

Sb, Sn, Ti, V, W, Zn, Zr) 19 ppm

Ta 8 ppm

Si 7 ppm

C <1 ppm

Cl <3 ppm

F 5 ppm

S <1 ppm

Nb ₂ O _{5 is} passed in a molybdenum boat through a small-sized tunnel furnace with a sliding hearth in an atmosphere of slowly entering hydrogen and kept in the hot zone of the furnace for 3.5 hours.

The resulting suboxide has a composition corresponding to NbO ₂ .

b) The product is placed on a fine-hole lattice, under which there is a crucible that contains 1.1 times more stoichiometric magnesium relative to the oxygen content of the suboxide.

A system containing a grate and a crucible is treated for 6 hours at a temperature of 1000 ° C in protective gaseous argon. During this treatment, magnesium evaporates and interacts with the upper layer of suboxide. The furnace is then cooled (<100 ° C) and air is gradually supplied to passivate the surface of the metal powder.

The product is washed with sulfuric acid until it is impossible to determine the presence of magnesium in the filtrate, and then washed to a neutral state with deionized water and dried.

Analysis of niobium powder gave the following impurity content:

About 20,000 ppm (3300 ppm / m ² )

Mg 200 ppm

Fe 8 ppm

Cr 13 ppm

Ni 3 ppm

Ta 110 ppm

From 19 ppm

N 4150 ppm

The particle size distribution determined by ASTM B822 corresponds to:

D10 4.27 μm

D50 160.90 μm

D90 318.33 μm

The size of the primary particles was determined visually as 500 nm. Scott bulk density is 0.946 g / cm ³ . The specific area of BET is 6.08 m ² / g. The fluidity determined in the Hall funnel is 38 seconds.

c) Anodes with a diameter of 3 mm, a length of 5.66 mm, anode mass of 0.14 g and a density of compressed material of 3.5 g / cm ³ are obtained from niobium powder by sintering on a niobium wire over time and at the temperature given in Table 1. 11.1.

The strength of the pressed anodes, determined using the apparatus of the company Ametec, USA, under the trade name Chatillon, is 6.37 kg. Anodes are formed at a temperature of 80 ° C in an electrolyte containing 0.1 vol.% H ₃ PO ₄ at a current density of 100/150 mA, at a voltage given in table. 11.1, and specific capacitor characteristics: see table. 11.1.

Example 12

Repeat the procedure of example 11 except that the temperature in the first stage of recovery is 1300 ° C.

Metal powder has the following properties:

D10 69.67 μm

D50 183.57 μm

D90 294.5 μm

Primary particle size

visually) 300-400 nm.

The specific surface area of BET is 5 m ² / g.

Free flowing.

The strength of the compressed material is very high: 13 kg with a density of compressed material of 3.5 g / cm ³ and 8 kg with a density of compressed material of 3 g / cm ³ .

After sintering at a temperature of 1100 ° C for 20 minutes (density of the compressed material 3 g / cm ³ ) and after molding at 40 V, the capacitance is 222498 μFV / g and the leakage current is 0.19 nA / μFV.

Example 13

This example demonstrates the effect of the reduction temperature in the first stage on the properties of niobium powder.

Three batches of niobium pentoxide are treated for 4 hours in a hydrogen atmosphere at temperatures of 1100, 1300 or 1500 ° C under conditions that are otherwise the same.

The batches are subsequently reduced to metallic niobium with gaseous Mg (6 hours, 1000 ° C). MgO, which was formed during this reaction, is washed with sulfuric acid along with an excess of Mg. Get a powder with the following properties (see table. 12).

Example 14

The precursor (Nb _x , Ta _1-x ) ₂ O _{5 is} obtained by co-precipitation of (Nb, Ta) oxyhydrate from a mixed aqueous solution of niobium and tantalum heptafluoride complexes by adding ammonia with stirring and subsequent calcination of the oxyhydrate to oxide.

A batch of mixed oxide powder having a nominal composition of Nb: Ta = 90:10 (weight ratio) is placed in a molybdenum boat and passed through a small-sized tunnel furnace with a rolling hearth in a slowly flowing hydrogen atmosphere and stored in the hot zone of the furnace for 4 hours at a temperature 1300 ° C. After cooling to room temperature, the composition is determined based on weight loss, which gives approximately (Nb _0.944 Ta _0.054 ) O.

Suboxide is placed on a grid with small holes, under which there is a crucible that contains magnesium 1.2 times the stoichiometric amount relative to the oxygen content in the suboxide. The system containing the grate and the crucible is treated for 6 hours at a temperature of 1000 ° C in protective gaseous argon. The furnace is then cooled to a temperature below 100 ° C and air is gradually supplied to passivate the surface of the metal powder.

The product is washed with sulfuric acid until it is impossible to determine the presence of magnesium in the filtrate, and then washed to a neutral state with deionized water and dried.

Analysis of the niobium powder gave a tantalum content of 9.73 wt.% And the following impurity content (ppm):

O: 20500, Mg: 24, C: 39, Fe: 11, Cr: 19, Ni: 2, Mo: 100.

The size of the primary particles, determined visually, is approximately 450 nm. The specific surface area of the BET is 6.4 m ² / g, the Scott density is 0.92 g / cm ³ , and the average particle size is 0.87 μm (FSSS).

Anodes with a diameter of 2.94 mm, a length of 3.2 mm and a density of pressed material of 3.23 g / cm ³ are obtained from the alloy powder by sintering on a niobium wire for 20 minutes at a temperature of 1150 ° C. The density of the sintered material is 3.42 g / cm ³ . The electrodes are anodized in an electrolyte containing 0.25% H ₃ PO ₄ to a final voltage of 40 V.

The characteristics of the capacitor are determined using a 10% aqueous solution of H ₃ PO ₄ and the following results are obtained: capacitance: 209117 μFV / g, leakage current: 0.55 nA / μFV.

Example 15

The alloy powder was prepared according to the procedure of Example 14 using an oxide powder with a nominal composition of Nb: Ta = 75:25 (weight ratio).

Analysis of the metal powder of the alloy showed a tantalum content of 26.74 wt.% And the following amount of impurities (ppm):

O: 15000, Mg: 25, C: 43, Fe: 9, Cr: 20, Ni: 2, Mo: 7, N: 247.

The size of the primary particles, determined visually, is approximately 400 nm. The specific surface area of BET is 3.9 m ² / g, Scott density is 1.09 g / cm ³ , Fischer particle size (FSSS) is 2.95 μm, Hall flow: 27.0 s.

Anodes with a diameter of 2.99 mm, a length of 3.23 mm and a density of pressed material of 3.05 g / cm ³ are obtained from the alloy powder by sintering on a niobium wire for 20 minutes at a temperature of 1150 ° C. The density of the sintered material is 3.43 g / cm ³ . The electrodes are anodized in an electrolyte containing 0.25% H ₃ PO ₄ to a final voltage of 40 V.

The characteristics of the capacitor are determined using a 10% aqueous solution of H ₃ PO ₄ and the following results are obtained: capacitance: 290173 μFV / g, leakage current: 0.44 nA / μFV.

Example 16

Tantalum hydroxide is precipitated from an aqueous solution of the tantalum fluorine complex by the addition of ammonia. The precipitated hydroxide was calcined at a temperature of 1100 ° C for 4 hours to obtain a Ta ₂ O ₅ precursor with the following physical data: average particle size: 7.3 μm (FSSS), Scott bulk density: 1.696 g / cm ³ , specific surface area (BET): 0.36 m ² / g, particle size distribution with laser diffraction using a Master Sizer S apparatus (ASTM B 822), measured without ultrasound: D10 = 15.07 μm, D50 = 23.65 μm, D90 = 34.03 microns.

The morphology of the agglomerated spheres is shown in Figs. 9A - 9C (SEM).

300 g of the pentoxide precursor are placed on a grate and 124 g of Mg (1.5 times the stoichiometric amount required to reduce the pentoxide to the metal) are placed on the bottom of the retort shown in FIG. 1.

A vacuum is created in the retort, filled with argon and heated to a temperature of 950 ° C for 12 hours. After cooling to a temperature below 100 ° C and passivation, the product is leached with an aqueous solution containing 23 wt.% Sulfuric acid and 5.5 wt.% Hydrogen peroxide, and then washed with water until neutral. The product is dried overnight at a temperature of 50 ° C and sieved <400 μm.

Analysis of tantalum powder gave the following results:

The average particle size of 1.21 microns (FSSS),

Scott bulk density: 1,556 g / cm ³ ,

BET surface: 2.20 m ² / g,

good fluidity

particle size: D10 = 12.38 μm, D50 = 21.47 μm, D90 = 32.38 μm,

morphology: see Fig. 10A-10C (SEM).

Chemical analysis:

A: 7150 ppm

N: 488 ppm

H: 195 ppm

S: 50 ppm

Si: 30 ppm

F: 2 ppm

Mg: 6 ppm

Na: 1 ppm

Fe: 3 ppm

Cr: <2 ppm

Ni: <3 ppm

The powder is soaked, with gentle stirring, with a solution of NH ₄ H ₂ PO ₄ containing 1 mg P per ml, dried overnight at a temperature of 50 ° C for doping with 150 ppm P and sieved <400 μm.

The capacitor anodes are obtained from 0.047 g of Ta powder each at a density of compressed material of 5.0 g / cm ^{3 by} sintering at a temperature of 1260 ° C with a holding time of 10 minutes.

The molding is carried out at a current density of 150 mA / g with a 0.1 wt.% Solution of H ₃ PO ₄ as an electrolyte for molding at a temperature of 85 ° C until the final voltage reaches 16 V, which is maintained for 100 minutes.

Test results:

Density of sintered material: 4.6 g / cm ³ ,

capacitance: 100577 μFV / g,

leakage current: 0.73 nA / μFV.

Example 17

Ta ₂ O ₅ with a high degree of optical purity is calcined at a temperature of 1700 ° C for 4 hours and then for 16 hours at a temperature of 900 ° C to obtain more compact and larger particles of the precursor.

Physical properties of pentoxide powder:

The average particle size of 20 μm (FSSS), bulk density according to Scott: 2.38 g / cm ³ .

Sieve analysis:

400-500 μm 8.7%

200-400 microns 63.6%

125-200 μm 15.0%

80-125 μm 7.2%

45-80 microns 3.8%

<45 μm 1.7%

Morphology is shown in FIGS. 11A – 11C (SEM).

The oxide powder is reduced to metal by the method of example 16, but at a temperature of 1000 ° C for 6 hours.

Leaching and P-doping is carried out according to the method of example 16.

Analysis of tantalum powder gave the following results:

The average particle size of 2.8 μm (FSSS),

Scott bulk density: 1.76 g / cm ³ ,

BET surface: 2.11 m ² / g,

fluidity through a non-vibrating funnel with an angle of 60 ° and a hole of 0.1 inch (0.254 cm): 25 g in 35 seconds,

particle size: D10 = 103.29 microns, D50 = 294.63 microns, D90 = 508.5 microns,

morphology: see Fig. 12A-12C (SEM).

Chemical analysis:

A: 7350 ppm

N: 207 ppm

H: 174 ppm

S: 62 ppm

Mg: 9 ppm

Fe: 5 ppm

Cr: <2 ppm

Ni: <3 ppm

P: 150 ppm

The anodes of the capacitor receive and anodize according to the method of example 16.

Test results:

Density of sintered material: 4.8 g / cm ³ ,

capacitance: 89201 μFV / g,

leakage current: 0.49 nA / μFV.

The second batch of capacitors is obtained by the same method, but the sintering temperature is increased to 1310 ° C.

Test results:

Density of sintered material: 5.1 g / cm ³ ,

capacitance: 84201 μFV / g,

leakage current: 0.68 nA / μFV.

Example 18

Several samples, each approximately 25 g, WO ₃ , ZrO ₂ and V ₂ O _{3 are} individually reduced with gaseous magnesium at a temperature of 950 ° C. for 6 hours. The reduction products are leached with dilute sulfuric acid to remove residual magnesium oxide. The product is a black metal powder in each case. Tungsten and zirconium powders have an oxygen content of 5.9 and 9.6 vol / vol%, respectively, which indicates that metal oxides are reduced to a metallic state.

This method is only a demonstration technique for producing high-quality chemically reduced niobium powder. The reduction of metal oxide with a gaseous reagent such as magnesium, as shown in this description, is particularly suitable for the production of powders used as substrates in metal-metal oxide capacitors. Although the reduction method is carried out with metal oxide in the bed in contact with a source of gaseous magnesium, the reduction can also be carried out in a fluidized bed, a rotary kiln, a suspension kiln, multiple hearth systems and similar systems providing a gaseous state of magnesium or another reducing agent. The method also works with oxides of other metals or mixtures of metal oxides, for which the reaction of reduction with gaseous magnesium or another reducing agent has a negative change in Gibbs free energy.

The above-described reduction with a gaseous agent has several advantages. Processing reduction products is much less complicated and expensive than processing after reduction of tantalum powder obtained by reactions in the liquid phase, such as sodium reduction of K ₂ TaF ₇ in a molten salt system. In this method, fluoride or chloride residues are not formed. This eliminates the potential serious problem of their removal or the need to use an expensive system for removing contaminants. The reduction of metal oxides with gaseous reducing agents gives powders with much larger surface areas compared to powders obtained by the molten salt / sodium reduction method. The proposed method makes it easy to obtain powders with a very high surface area, compared with the traditional method; the potential for producing highly effective powders suitable for use in capacitors with magnesium or other gaseous reducing agents is quite large.

The invention also primarily demonstrates the superiority of Ta-Nb alloy powders for use in the manufacture of capacitors.

On Fig shows the ratio of the maximum obtained capacitive resistance (μFV / g) and the BET surface of the powder (m ² / g) with respect to the alloy composition. A and C indicate pure powders Ta and Nb, respectively, measured in this example 16. B denotes the highest known values for capacitors based on pure powder Ta described in examples 2, 5 and 7 of WO 98/37249. Line 1 denotes the expected values for the capacitors based on the alloy powder from linear interpolation from capacitors based on pure powders Ta and Nb. E denotes a dummy capacitor based on powder Nb, where the insulating oxide layer has the same thickness per volt as in capacitors based on powder Ta, however, the dielectric constant of niobium oxide is different. Line 11 denotes a linear interpolation between B and E. D denotes the measured value of the capacitor based on an alloy powder of 25 wt.% Ta / 75 wt.% Nb, as shown in example 15 of this description. Curve III denotes the calculated dependence of the capacitance on the composition of the alloy in the capacitors based on the alloy powder according to this invention.

On Fig presents a block diagram of the stages of obtaining an electrolytic capacitor of the present invention. The steps include reducing a metal oxide with a gaseous reducing agent; separating the oxide of the reducing agent from the mass of the obtained metal; grinding to powder and / or primary powder particles; sorting; optional preliminary sintering to obtain agglomerated secondary particles (controlled mechanical methods and control of the original reduction or separation stages also affect the production of agglomerates); deoxygenation to reduce oxygen concentration; compaction of primary or secondary particles to a porous coherent mass by cold isostatic pressing with or without the use of binders for compaction or lubricating agents; sintering to porous anodes (which may have an elongated cylindrical shape, or a bar shape, or a short shape, such as shavings); attaching the leads to the anodes by inserting them into the anode before sintering or by welding to the sintered anode; forming open metal surfaces inside the porous anode by electrolytic oxidation to obtain a dielectric oxide layer; impregnation of the solid electrode by introducing the precursors into the porous mass and pyrolysis in one or more stages or using other methods of impregnation; cathode equipping and assembly. Various additional stages of cleaning and testing are not shown. The final product is shown (in cylindrical form) in FIG. 15 as a Ta or Nb (or Ta-Nb alloy) capacitor 101 in partially cut form as a porous Ta or Nb (or Ta-Nb alloy) anode 102 impregnated with a solid an electrolyte surrounded by a counter electrode (cathode) 104 and a packing sheath 105 with a dense wire lead 106 from Ta or Nb (usually a powder composition), which is connected to the anode by a welded joint 107. As mentioned above, other capacitors known in themselves (of a different shape, from other metals, with others with Stem electrolytes, anode output connection, and so on) are available in the present invention.

14 is a flowchart generally illustrating the preparation of some other derivative products and the use of the present invention, including the use of powders as strips, in foundry molds and individual loose packaging units for further interaction and / or compaction by sintering, hot isostatic pressing (GUI) or by sintering / GUI methods. The powders themselves and / or in a compacted form can be used in the preparation of composites, during combustion, in chemical synthesis (as reagents) or in catalysis processes, in the preparation of alloys (for example, ferrometallurgy) and as coatings. Compacted powders can be used to obtain factory products and finished structural elements.

In some cases, the final useful products obtained using powders obtained by reduction with a gaseous agent will be identical to the powders of the prior art obtained by methods of the prior art (for example, reconstituted powders), and in other cases the products will be new and have unique physical, chemical and electrical characteristics obtained from the unique forms, as described in this invention, of powders obtained by reduction with gaseous reducing agents. The methods of transition from powder production to the final product or end use are also modified in accordance with the powders and methods for their preparation, methods for obtaining modified profiles of impurities and morphology.

Production of factory products and prefabricated structural elements may include remelting, casting, annealing, dispersion hardening, and other types of processing that are well known in themselves. Final products obtained by further reaction of metal powders may include oxides, nitrides, silicides and further derivatives with a high degree of purity, such as a ceramic complex used in ferroelectrics and optics, for example, PMW compounds of perovskite structure.

It will be apparent to those skilled in the art that other options, improvements, details, and methods of use may be included within the scope of this invention and are encompassed by this patent, which is limited only by the claims made in accordance with patent law, including the theory of equivalents.

Claims (68)

1. A method of producing a metal powder selected from the group consisting of tantalum, niobium and their alloy, comprising reducing, characterized in that the oxide or mixture of oxides of the obtained metal (s) is preliminarily obtained in the form of an oxide porous mass having the form through which gas can be passed, a gas is used as a reducing agent, which is obtained outside the oxide mass and the reduction is carried out by passing a gaseous reducing agent through this mass at an elevated temperature, at m the choice of reagents, porosity of the oxide, temperature and reaction time of the reduction reaction is carried out in such a way as to obtain essentially complete reduction of the oxide (s) with the release of its metal part and to obtain the residual oxide of the reducing agent formed during the reaction, which can be easily removed, to obtain a powder with a high surface area index, a powder selected from the group consisting of tantalum, niobium and their alloy, in pure form or with one or more metals, is selected from the group consisting of titanium, molybdenum, tungsten, hafnium, vanadium and zirconium, added to them or obtained together with them. 2. The method according to claim 1, characterized in that the reducing agent is selected from the group consisting of magnesium, calcium, aluminum, lithium, barium, strontium and their hydrides. 3. The method according to claim 1 or 2, characterized in that the obtained metal or alloy powder is processed to obtain an agglomerated secondary form. 4. The method according to any one of claims 1 to 3, characterized in that the metal powder is deoxygenated by additional treatment with a gaseous reducing agent. 5. The method according to any one of claims 1 to 4, characterized in that the metal consists essentially of tantalum and the oxide is tantalum pentoxide. 6. The method according to any one of claims 1 to 4, characterized in that the metal is niobium and the oxide is niobium pentoxide or niobium suboxide. 7. The method according to claim 6, characterized in that the oxide contains tantalum in an amount up to 50 at.% With respect to the total metal content. 8. The method according to any one of claims 1 to 7, characterized in that the mass of oxide in the form through which gas can be passed gives a void volume of at least 90%. 9. The method according to any one of claims 1 to 8, characterized in that the oxide has the form of agglomerated primary particles with diameters from 100 to 1000 nm, and the average size D50 of the agglomerate particles determined by ASTM-B822 is from 10 to 1000 microns. 10. The method according to any one of claims 1 to 9, characterized in that the reducing agent is magnesium. 11. The method according to any one of claims 1 to 10, characterized in that the elevated temperature while passing the gaseous reducing agent through the oxide mass is maintained below 0.5 TM, where TM is the melting point of the metal powder. 12. The method according to claim 11, characterized in that the temperature is maintained below 0.4 TM. 13. The method according to any one of claims 1 to 12, characterized in that the metal powder is subjected to further deoxygenation to obtain the final powder. 14. The method according to item 13, characterized in that carry out one or more final stages of deoxygenation, which is a continuation of the recovery reaction. 15. The method according to 14, characterized in that the final deoxygenation is a separate processing process. 16. The method according to any one of claims 1 to 15, characterized in that the metal powder is processed to obtain an agglomerated secondary form. 17. The method according to clause 16, characterized in that for the agglomerated secondary form of the powder carry out deoxygenation. 18. The method according to any one of claims 1 to 17, characterized in that the metal powder is formed into a coherent porous mass. 19. A method of obtaining a metal powder selected from the group consisting of tantalum and / or niobium and from their alloy, comprising reduction, characterized in that the oxide or mixture of oxides of the obtained metal (s) is preliminarily obtained in the form of an oxide porous mass, having a form through which gas can be passed, then a gas containing hydrogen is passed through the porous oxide mass at an elevated temperature, and the oxide porosity, temperature and reaction time of the reduction are selected so as to remove at least 20% of the oxygen contained in the oxide to produce suboxide and carry out further reduction of the suboxide in the second stage with reducing agents selected from the group of reducing metals and hydrides of reducing metals, for almost complete reduction of the oxide with the release of its metal part, and a powder is obtained selected from the group consisting of tantalum and / or niobium and their alloy, in pure form or with one or more metals selected from the group consisting of titanium, molybdenum, ox Fram, hafnium, vanadium and zirconium are added to or received together with them. 20. The method according to claim 19, characterized in that the reducing agent is selected from the group consisting of magnesium, calcium, aluminum, lithium, barium, strontium and their hydrides. 21. The method according to claim 19 or 20, characterized in that the obtained metal or alloy powder is processed to obtain an agglomerated secondary form. 22. The method according to any one of paragraphs.19-21, characterized in that the metal powder is deoxygenated by additional treatment with a gaseous reducing agent. 23. The method according to claim 19, characterized in that the recovery in the first stage is carried out at least until the volume of the solid substance decreases by 35-50%. 24. The method according to claim 19 or 23, characterized in that the reduction in the first stage is carried out to obtain MeO _x , where Me is tantalum and / or niobium and x has a value from 1 to 2. 25. The method according to any one of paragraphs.19, 23 or 24, characterized in that the reduction product obtained in the first stage is maintained at a temperature approximately equal to the reduction temperature for 60-360 minutes. 26. The method according to any one of claims 19 or 23-25, characterized in that magnesium, calcium and / or their hydrides are used as reducing agents in the second stage. 27. The method according to any one of paragraphs.19-26, characterized in that the metal consists essentially of tantalum and the oxide is tantalum pentoxide. 28. The method according to any one of paragraphs.19-27, characterized in that the metal is niobium, and the oxide is niobium pentoxide or niobium suboxide. 29. The method according to p. 28, characterized in that the oxide contains tantalum in an amount up to 50 at.% In relation to the total content of metals. 30. The method according to any one of paragraphs.19-29, characterized in that the mass of oxide in the form through which gas can be passed has a void volume of at least 90%. 31. The method according to any one of paragraphs.19-30, characterized in that the oxide has the form of agglomerated primary oxide particles with diameters from 100 to 1000 nm, and the average particle size D50 of agglomerate determined according to ASTM-B822 is from 10 to 1000 microns. 32. The method according to any one of paragraphs.19-31, wherein the reducing agent is magnesium. 33. The method according to any one of paragraphs.19-32, characterized in that the elevated temperature while passing the gaseous reducing agent through the oxide mass is maintained below 0.5 TM, where TM is the melting point of the metal powder. 34. The method according to p, characterized in that the temperature is maintained below 0.4 TM. 35. The method according to any one of paragraphs.19-34, characterized in that the metal powder is subjected to further deoxygenation to obtain the final powder. 36. The method according to clause 35, wherein one or more of the final stages of deoxygenation, which are a continuation of the recovery reaction, are carried out. 37. The method according to clause 36, wherein the final deoxygenation is a separate processing process. 38. The method according to any one of paragraphs.19-37, characterized in that the metal powder is processed to obtain an agglomerated secondary form. 39. The method according to § 38, characterized in that for the agglomerated secondary form of the powder, deoxygenation is carried out. 40. The method according to any one of paragraphs.19-39, characterized in that the metal powder is formed into a coherent porous mass. 41. Niobium powder in the form of agglomerated primary particles, characterized in that the primary particle size is from 100 to 1000 nm, and the agglomerates have a particle size of D10, D50 and, accordingly, D90 particles of 3 to 80 μm as determined by ASTM-B822, from 20 to 250 microns and, accordingly, from 30 to 400 microns. 42. The powder according to paragraph 41, characterized in that it contains up to 40 at.% Tantalum in pure form or with one or more metals selected from the group consisting of titanium, molybdenum, tungsten, hafnium, vanadium, zirconium, in relation to total metal content. 43. The powder according to § 42, characterized in that it contains at least 2 at.% Of another metal (s). 44. The powder according to § 42, characterized in that it contains at least 3.5 at.% Of another metal (s). 45. The powder according to claim 42, characterized in that it contains at least 5 at.% Of another metal (s). 46. The powder according to § 42, characterized in that it contains at least 10 at.% Of another metal (s). 47. The powder according to any one of paragraphs 42-46, characterized in that it contains up to 34 at.% Other metal (s). 48. The powder according to any one of paragraphs 42-47, characterized in that it contains tantalum as another metal. 49. The powder according to any one of paragraphs 42-48, characterized in that it consists essentially of agglomerated spherical primary particles with an average diameter of from 100 to 1500 nm. 50. The powder according to any one of paragraphs 42-49, characterized in that it has a product of surface area according to BET and the density of the alloy from 8 to 250 (m ² / g) · (g / cm ³ ). 51. A powder according to any one of claims 42-50, characterized in that it has a Scott density to alloy density ratio of 0.09 to 0.14 (g / cm ³ ) / (g / cm ³ ). 52. A powder according to claim 49, characterized in that the size D50 of the agglomerate particles determined by ASTM-B822 is from 20 to 300 microns. 53. Powder according to any one pp.42-52, characterized in that it contains oxygen in an amount of 2500-4500 million ^-1 / m ² surface BET, ^-1 to 10000 million of nitrogen to carbon ^-1 150 million and less than ^-1 500 million metal impurities. 54. The powder according to any one of paragraphs 42-52, characterized in that after sintering at a temperature of 1100 ° C and molding at 40 V, it has a specific capacitance of the capacitor from 80,000 to 250,000 μFV / g and a specific leakage current density of less than 2 nA / μFV. 55. The powder according to any one of paragraphs 42-52, characterized in that after sintering at a temperature of 1250 ° C and molding at 40 V, it has a specific capacitance of the capacitor from 30,000 to 80,000 μFV / g and a specific leakage current density of less than 1 nA / μFV. 56. The powder according to paragraph 41, characterized in that it contains up to 40 at.% Tantalum with respect to the total content of niobium and tantalum and is used for the production of electrolytic capacitors. 57. The powder according to p. 56, characterized in that it contains at least 2 at.% Tantalum. 58. The powder according to p. 56, characterized in that it contains at least 3.5 at.% Tantalum. 59. The powder according to p. 56, characterized in that it contains at least 5 at.% Tantalum. 60. The powder according to p. 56, characterized in that it contains at least 10 at.% Tantalum. 61. The powder according to p. 56, characterized in that it contains from 12 to 34 at.% Tantalum. 62. A powder according to any one of claims 56-61, characterized in that the agglomerated particles in the form of flakes have a product of BET surface area and alloy density from 8 to 45 (m ² / g) · (g / cm ³ ). 63. A powder according to any one of paragraphs 56-61, characterized in that the agglomerated spherical primary particles have a diameter of from 100 to 1500 nm and a product of surface area by BET and density from 15 to 60 (m ² / g) · (g / cm ³ ). 64. A powder according to any one of claims 56-63, characterized in that it has an average particle size D50 of 20 to 250 microns as determined by ASTM-B822. 65. The powder according to any one of claims 56-64, characterized in that it has a Scott density and alloy density ratio of 0.09 to 0.18 (g / cm ³ ) / (g / cm ³ ). 66. A powder according to any one of claims 56-65, characterized in that after sintering and molding it has a ratio of specific capacitance and surface area according to BET of the powder of more than 65,000 (μFV / g) / (m ² / g), preferably more than 70,000 (μFV / g) / (m ² / g). 67. A method for producing a powder, including hydrogenating an electron beam smelting alloy ingot, grinding the hydrogenated alloy ingot, dehydrogenating the milled alloy, molding the milled alloy into flakes, agglomerating the obtained alloy flakes in the presence of an alkaline earth metal as a reducing agent, leaching and washing the agglomerated alloy flakes for removal of any residues and residual product of a reducing agent, characterized in that the powder according to item 56 is produced and hydrogenated w is subjected to the alloy ingot containing Nb and up to 40 at.% of tantalum based on the total content of niobium and tantalum, and the agglomeration is carried out at a temperature of from 800 to 1150 ° C. 68. The method according to p, characterized in that during the agglomeration, the alloy powder is doped with phosphorus and / or nitrogen. Priority on points and signs: According to claim 1, for the sign “receive a powder selected from the group consisting of tantalum and niobium in pure form”, priority is established according to US 09/073488 of 05/06/1998, and for the sign “receive a powder selected from the group consisting of alloy tantalum and niobium, in its pure form or with one or more metals selected from the group consisting of titanium, molybdenum, tungsten, hafnium, vanadium and zirconium, added to them or obtained together with them ”, priority is established according to DE 19831380.1 from 07.13.1998 . According to claim 9, for the sign “the oxide has the form of agglomerated primary particles with diameters from 100 to 1000 nm, and the average size D50 of the agglomerate particles determined by ASTM-B822 is from 20 to 1000 μm”, priority is established according to DE 19831380.1 from 07.13.1998, and for the sign “D50 from 10 to 20 microns” priority is set according to PCT / US99 / 09772 of 05/05/1999. According to clause 31, for the sign “the oxide has the form of agglomerated primary oxide particles with diameters from 100 to 1000 nm, and the average size D50 of the agglomerate particles determined by ASTM-B822 is from 20 to 1000 μm”, priority is established according to DE 19831380.1 from 07.13.1998, and for the sign “D50 from 10 to 20 microns” priority is set according to PCT / US99 / 09772 of 05/05/1999. According to paragraph 41, for the sign “the size of the primary particles is from 100 to 1000 nm, and the agglomerates have a particle size of D10, D50 and, correspondingly, D90, constituting from 3 to 80 μm, from 70 to 250 μm, and correspondingly D90, respectively , from 230 to 400 microns ”priority is set according to DE 19831380.1 from 07/13/1998, and for the characteristic“ D50 from 20 to 70 microns, D90 from 30 to 230 ”priority is set according to PCT / US99 / 09772 from 05/05/1999.

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