JP2004522851A - Metal and alloy powders and powder manufacturing - Google Patents

Abstract

A precursor powder containing a metal compound is formed into a sample for electro-deoxidation, for example, by slip casting. The sample is then immersed in the melt containing the molten salt, and a cathodic potential is applied to remove non-metallic species from the precursor powder by electro-deoxidation and dissolution in the melt. This typically forms a metal sample that has been fragmented to form a metal powder. In a second aspect of the present invention, a powdered feedstock is formed into a modeling precursor, and more extensive electro-deoxidation is performed to form a product closer to a mesh.

Description

【Technical field】
[0001]
(Field of the Invention)
The present invention relates to a method and an apparatus for preparing metal powders and compositions of well-defined particle size, and to metal powders so produced. In a further aspect, the present invention relates to powder production and production of products that are close to a mesh shape.
[Background Art]
[0002]
(Background of the Invention)
Metal powders have a number of uses, including:
(A) As a feedstock for powder metallurgy, it offers the possibility to make products that are close to mesh-shaped rather than having to machine large billet-derived components. In some cases, 90% of the material needs to be removed during the machining process and recycled. Methods for making products that resemble a mesh shape can advantageously reduce this waste.
(B) Alloys; the use of metal powders in alloy preparation results in rapid melting and minimal segregation in the alloy.
(C) Due to their aesthetic properties: Metal powders are often used in metal coatings.
(D) As fuel in rockets.
(E) For example, as a fine powder to be mixed as an alloy component in producing a large number of high-strength magnetic phases.
[0003]
There are various conventional methods of making metal particles. These include crushing and grinding, which are energy intensive processes especially when the metal inherently resists deformation, and for reactive metals, the grinding process is performed under inert conditions to avoid oxidation There is a need. Metal powders can also be obtained by reduction of metal compounds, such as oxides, with hydrogen, but are generally limited to oxides that are less stable than water vapor. Reducing oxides of highly reactive metals requires reactants such as calcium, and the powder is then susceptible to calcium oxide contamination.
[0004]
Injection of the molten metal onto the spinning disk results in fine particles of liquid being ejected from the disk by centrifugal force as droplets that subsequently solidify. Liquid metal can be powdered by impinging a high velocity gas into a stream of molten metal. The metal powder can be produced by impact cooling metal vapor. For some metals with considerable hydrogen solubility, it is possible to form brittle hydrides that can then be broken up or calcined into fine particles. By heating at an elevated temperature, the hydride easily decomposes to form metal particles. Finally, electrochemical deposits of metals from metallic compounds dissolved in aqueous or molten salt electrolytes can result in dendritic deposits that can be easily crushed into a fine powder. In general, these methods can give fine powders, which are frequently highly oxidized and contaminated with oxide products, and generally have a considerable range of particle sizes. Exists. This is particularly problematic when metal powders of a given particle size are required, requiring sieving of the product and removal of significant fractions. These problems are exacerbated when alloy powders, especially those of the most reactive metals, are required.
[0005]
Metal oxide powders are much easier to obtain by grinding, since oxides are typically highly friable and easily crushed. Being oxides, they do not suffer from oxidation during this process. Very fine oxide powders can also be produced by precipitation from aqueous or molten salt solutions. Alternatively, it may be possible to form a fine oxide powder by reacting a volatile compound with oxygen. For example, the reaction of titanium tetrachloride with oxygen produces a very fine oxide powder. Frequently, these particles are of uniform size, but the problem of producing fine metal powders remains.
DISCLOSURE OF THE INVENTION
[Means for Solving the Problems]
[0006]
(Summary of the Invention)
In a first aspect, the present invention provides a method and an apparatus for producing a metal powder, as defined in the accompanying independent claims, and a metal powder. Preferred or advantageous features of the invention are set out in the dependent claims.
[0007]
This aspect of the invention is based on the surprising discovery that a powdered metal compound, such as a metal oxide powder, can be electrochemically treated to yield a metal powder having a uniform structure and size. Accordingly, a method for producing a metal powder may be advantageously provided wherein the metal (M ¹ ) And the nonmetallic species (X) (M ¹ The precursor powder containing X) is processed by electro-deoxidation. In this process, the precursor powder is mixed with molten salt (M) under conditions such that the non-metallic species dissolve in the melt. ^Two Forming a cathode in contact with the melt containing Y). This can advantageously form a porous metal sample that can be processed if needed to form a metal powder.
[0008]
Surprisingly, it has been found that metal powders produced according to embodiments of the present invention have a uniform microscopic structure, both in terms of the particle size of the metal powder and the microstructure of the individual particles. Furthermore, it has been found that particles of a similar shape can be produced. For example, the powder may form a cubic structure. The small, consistent particle size and metal purity produced by this method are particularly advantageous since the production of metal powders by prior art methods has not been able to produce such materials in high yields; In the process of technology, sieving is generally required to prepare a consistent particle size and involves very significant waste.
[0009]
The term "electro-deoxidation" refers to the conversion of a non-metallic species from a solid state compound by contacting the compound with a melt and applying a cathodic voltage thereto to dissolve the non-metallic species (i.e., anionic species). Used herein to describe the process of removing (X). In electrochemistry, the term "oxidation" means a change in the oxidation state and does not necessarily imply a reaction with oxygen. However, it should not be inferred that electro-deoxidation always involves a change in the oxidation state of both (or all) of the components of the compound; this is due to the nature of the compound (eg, it is primarily ionic). Or covalent). Furthermore, it should not be assumed that electro-deoxidation can be applied only to oxides; any compound can be treated in this manner. Other terms to describe the electro-deoxidation process in a particular case can be electro-decomposition, electro-reduction or solid-state electrolysis.
[0010]
In a preferred embodiment, the cathodic voltage applied to the metal compound is lower than the voltage for the deposition of cations from the molten salt on the cathode surface. This may advantageously reduce the incorporation of cation-containing intermetallic compounds. This is because under one embodiment, the decomposition potential of the salt (or electrolyte) does not exceed the limit during electro-deoxidation (or electro-reduction), or the molten salt M ^Two By electrolysis of a mixture of Y or a salt, a metal compound (M ¹ X) under the conditions of one embodiment providing a method for producing a metal powder by processing the powder of ^Two A reaction (or ionization) of X but not deposition occurs at the electrode surface and X is the electrolyte M ^Two It is believed that this can be achieved under conditions that dissolve in Y.
[0011]
Further details of the electro-deoxidation process are disclosed in International Patent Application No. PCT / GB99 / 01781, which is hereby incorporated by reference in its entirety.
[0012]
In the method of the present invention, the metal produced preferably has a higher melting point than the melting point of the melt (or salt).
[0013]
Additionally, other metal compounds (eg, metal oxides) may be present, and the electrolysis product may be an alloy powder.
[0014]
The method of the present invention can advantageously provide a product having a very uniform particle size and no oxygen or other contaminants.
[0015]
According to a preferred embodiment of the present invention, the electrochemical reduction of the metal oxide powder by ionizing oxygen from the oxide by the cathode produces agglomerates of the pure metal powder, the particle size of which is reduced It depends on the conditions of preforming and sintering, and the time and temperature of the electro-deoxidation (or electrolysis). Other electrolysis parameters such as voltage, current and salt composition can also be varied to control the morphology of the metal powder. Control of these parameters may be advantageously applicable to precursor powders rather than oxides.
[0016]
The metal compound or oxide should exhibit at least some electronic conductivity or be used in contact with a conductor.
[0017]
The metal alloy powder may be advantageously formed by electro-deoxidation of a precursor powder comprising a mixture or solid solution of two or more metal compounds or one or more metals or an alloy having one or more metal compounds.
[0018]
In a second aspect, the present invention may advantageously provide a method for forming a product close to a mesh shape. In this method, the shaped precursor is a metal (M ¹ ) And the nonmetallic species (X) (M ¹ X). The precursor is then treated by electro-deoxidation, and the precursor is treated with a molten salt (M.sub.M) under conditions such that the non-metallic species dissolves in the melt. ^Two Forming a cathode in contact with the melt containing Y). Electro-deoxidation takes a long enough time to form an interconnect between the metal powder particles produced by electro-deoxidation and / or to produce a product close to the network shape strong enough for further processing. Or run at a sufficiently high temperature.
[0019]
The advantages of the powder production aspect of the invention described above may also be applicable to this aspect of the invention. For example, performing electro-deoxidation at a cathodic potential that is less than the potential for cation precipitation from the melt can advantageously reduce incorporation of products that are close to a network shape, and can be a mixture of two or more metals or Using a feed containing a solid solution can advantageously produce a product that approximates the network shape of the desired alloy. One of ordinary skill in the art will readily appreciate that other advantages described above may also be applicable to products that are close to a mesh shape.
[0020]
(Specific embodiments and best modes of the invention)
Embodiments of the present invention will now be described by way of example with reference to the drawings.
[0021]
1 and 2 show a pellet 2 of metal oxide in contact with the cathode conductor. Each pellet is prepared by a powder processing technique (eg, pressing or slip-casting a submicron or micron sized powder such as titanium dioxide (FIG. 3)). This pellet is then burned to give it structural strength before the cathode is made in a cell in which crucible 6 contains molten salt 8. In this embodiment, the cell contains a chloride salt (CaCl 2). _Two Or BaCl _Two Or eutectic mixtures thereof with each other or with another globide salt such as NaCl).
[0022]
In the embodiment of FIG. 1, the pellet is annular and is threaded through the cathode conductor in the form of a kanthal wire 4. This crucible is an inert crucible of graphite or alumina. In the embodiment of FIG. 2, crucible 12 is made from a conductive material such as titanium or graphite. The pellet sinks into the melt and contacts the crucible, to which a cathodic voltage is applied. Thus, the crucible itself acts as a current collector.
[0023]
In both embodiments, the electrochemical process is the same as follows. Upon application of a current, oxygen ionizes, dissolves in the salt, and diffuses into the discharged graphite anode 10. This removes oxygen from the oxide, leaving behind the metal. The metal product is a very fine powder of very uniform size, as shown in FIG. It should be noted that the prepared metal powder has a much larger particle size than the original particle size of the oxide powder. By changing the time, temperature, voltage, current and / or salt of the electro-deoxidation (reduction), it is possible to change and control the size and morphology of the metal powder.
[0024]
The above embodiments produce titanium metal powders, but by simply mixing the oxide powders together, and preferably by burning or sintering them to strengthen the pellets. It is possible to make the alloy powder by the same route. The pellets can also be burned to form a solid solution of the oxide. Oxide powders are submicron in particle size and finer than the metal powders produced.
[0025]
It should consist of a salt that is more stable than the equivalent salt of the metal produced, and preferably the salt should be as stable as possible so that it can remove oxygen to the lowest possible concentration. Salt choices include chlorides or other halide salts of alkali and / or alkaline earth metals, especially barium, calcium, cesium, lithium, strontium and yttrium.
[0026]
A mixture of salts (preferably a eutectic composition) may be used to obtain a salt with a lower melting point provided by the pure salt and / or to modify the interaction between the cathode and the electrolyte .
[0027]
At the end of the reduction, the reduced compact is recovered from the molten salt. However, some of the salt is contained in the recovered pellets, stopping the oxidation of the powder. The salt can be easily removed by washing in water or an organic solvent such as ethanol. In general, the pellets are very brittle and can be easily broken to show metal powder.
BEST MODE FOR CARRYING OUT THE INVENTION
[0028]
The following examples illustrate the invention.
[0029]
(Example 1)
Three pellets (5 mm diameter and 1 mm thick) prepared by pressing a moistened 0.25 μm titanium dioxide powder (FIG. 3) and drying and sintering in air at 950 ° C. for 2 hours were dried at 950 ° C. Placed in a crucible of titanium filled with molten calcium chloride. FIG. 2 shows the cell arrangement. A potential of 3 V was applied between the graphite anode and the titanium crucible. After 10 hours, the electro-deoxidation was terminated, the salt was allowed to solidify and then dissolved in water to show a black / metal pellet, which was then removed from the crucible and dried. Examination under a scanning electron microscope showed that the particle structure of the pellets changed from 0.25 μm titanium dioxide particles to 12 μm titanium particles (FIG. 4). The titanium particle size is advantageously very uniform, about 12 μm +/− 3 μm. In the experimental error, no oxygen was detected by energy dispersive X-ray analysis.
[0030]
It should be noted that in other experiments it was observed that increasing the duration of the electrolysis increased the size of the particles, and at the same time, the interconnectivity between individual particles became significantly stronger. This can ultimately result in the production of solid metal pellets that cannot be crushed into a powder, and therefore in the form of a product that is close to a mesh. In addition, such strong pellets can be used directly as feedstock for various fabrication technologies (eg, sintering). The microstructure in these solid pellets is believed to be similar to the structure in a conventional Kroll titanium sponge. The formation of titanium pellets also depends on the nature of the dissolved salt and other experimental conditions such as pre-forming conditions and sintering of the pellets.
[0031]
(Example 2)
TiO as in Example 1 _Two The powder was mixed with water to form a slurry, then slip cast into small pellets, dried and sintered at 950 ° C. in air for 2 hours. The sintered pellet was approximately 8 mm in diameter and 2 mm thick. Holes (1.5 mm diameter) are made of sintered TiO _Two Dried into each of the pellets. Two of these were passed through a Kanthal wire (1.5 mm diameter) and then inserted at 950 ° C. into a molten eutectic mixture of calcium chloride and barium chloride. An alumina crucible was used to contain the salt and the cell arrangement is as shown in FIG. A potential of 3.1 V was applied between the graphite anode and the Kanthal wire. After about 20 hours, the temperature is reduced to 700 ° C., and the pellets on the Kanthal wire are removed from the crucible, cooled in air, and then washed in water to show gray / metal pellets. Examination under a scanning electron microscope showed that the particle structure of each pellet changed from 0.25 μm titanium dioxide particles to two types of titanium particles (about 3 μm and about 12 μm, respectively) (see FIG. 5). That).
[0032]
As shown in Example 1 above, with proper control of the process parameters, it is possible to produce a titanium powder with a more consistent particle size, but the particles produced in Example 2 It should be noted that the size range may advantageously be substantially more uniform than the size range produced by prior art methods.
[0033]
(Example 3)
1 μm chromium oxide powder is mixed with water to form a slurry, slip cast into small samples (or pellets) about 8-10 mm in diameter and 3-5 mm thick, then dried and dried at 950 ° C. in air at 2 ° C. Sintered for hours. After sintering, no significant change in the color (green) and size of the sample was observed, but the mechanical strength was significantly enhanced. The three sintered samples were placed in a graphite crucible filled with calcium chloride melted at 990 ° C., as shown in FIG. Better results were obtained by adding NaCl to the melt and reducing the dissolution of chromium oxide in the melt. A potential of 2.7 V was applied between the graphite anode and the graphite crucible. After 15 hours, the electrolysis was terminated, the salt solidified and then dissolved in water to show a gray / metal pellet. Examination under a scanning electron microscope (FIG. 6) showed aggregates of two sizes of crystallites in the reduced sample; large crystallites were 20-50 μm in size, while small crystallites were 5 μm in size. ８8 μm. Energy dispersive X-ray analysis confirmed that both types of crystallites were pure chromium metal.
[0034]
The range of particle sizes produced in this example can be reduced by controlling the parameters of the process, but is significantly narrower than the range of chromium particle sizes produced by prior art methods (typically by mechanical milling). .
[0035]
(Example 4)
Titanium dioxide (0.25 μm particle size), alumina (0.25 μm) and vanadium oxide (1-2 μm) powders were prepared using the same metal element ratio as the desired alloy (in this example, Ti-6Al-4V ). The mixture was then allowed to make a slurry with water and slip cast into pellets, then dried and sintered at 950 ° C. for 2 hours in air. After sintering, the color of the pellet changed from light green to dark brown. The size of the sintered pellet was about 8 mm in diameter and 6 mm in thickness. After drilling a hole 1.5 mm in diameter, one of the sintered pellets was passed through a Kanthal wire and then inserted at 950 ° C. into a molten eutectic mixture of calcium chloride and barium chloride. An alumina crucible was used to contain the molten salt and the cell configuration is shown in FIG. A potential of 3.1 V was applied between the graphite anode and the Kanthal wire. After 20 hours, the temperature of the salt is reduced to 700 ° C. and the electro-deoxidation is terminated. The pellet on the Kanthal wire is removed from the crucible, cooled in air, and then washed / immersed in water to reveal a gray / metal pellet. Examination under a scanning electron microscope showed that the particle structure of the pellet was similar to the particle structure for titanium shown in FIG. EDX analysis showed, within experimental error, the absence of oxygen in the pellet, confirming the presence of titanium, aluminum and vanadium in the individual particles at the desired ratio.
[0036]
(Example 5)
Al _Three O _Three And NiO powder were mixed in a molar ratio of 1: 6, pressed into small cylindrical pellets (10 mm in diameter and 5-10 mm in height), and sintered in air at 980-1000 ° C. for about 2 hours. . After sintering, the gray-green pellets became slightly lighter in color. A 1.7 mm diameter hole is drilled in the sintered pellet. Four sintered pellets (weighing about 4 grams) were passed through a Kanthal wire (1.0 mm diameter) to form an assembled cathode. The electro-deoxidation was performed at 950 ° C. for about 18 hours at 3.1 V with Argon-protected molten CaCl 2 as shown in FIG. _Two The assembly was performed between a cathode and a graphite anode. The pellet was removed from the molten salt upon reduction and cooled first in argon and then to room temperature in air. The reduced pellet was washed using water and then dried in air to give a gray metallic color. The surface and cross-section of the reduced pellet consisted of nodular particles 2-20 microns in size and contained Al and Ni in an atomic ratio of 1: 3. No oxygen was detected. The pellet was then manually ground to a powder in an agate mortar. XRD (X-ray diffraction) was applied to the powder, and the spectrum showed that standard AlNi _Three The pattern was almost the same as the sample (FIG. 8).
[0037]
(Example 6)
Nb used in the experiment _Two O _Five The powder was 99.97% and 99.99% by weight pure and had an average particle size of 4.03 μm and 12.71 μm, respectively. The powder was then pressed into a porous compact and then strengthened by sintering. The sintered pellet is attached to a cathode current collector to form an assembled oxide cathode. CaCl used for the melt _Two 2H _Two O and NaCl were the analytical reagents. All chemicals were supplied by Aldrich Chemical. CaCl _Two 2H _Two O was dehydrated in air at 373K for 1 hour, slowly heated to 573K, and then maintained at 573K for 12 hours. Dehydrated CaCl _Two And dried NaCl were mixed thoroughly, then the mixture was dried at 473 K before use. High density graphite rods 10 mm in diameter and 100 mm in length were purchased from Graphite Technologies and used as anodes. Kanthal® wire (1.5 mm diameter) was used as the cathode current collector.
[0038]
An electrolytic cell for electrolysis is shown schematically in FIG. Two Farnell LS30-10 Automotive Power Supplies were used to perform electrolysis under constant voltage. Nb _Two O _Five A first wire 50 for connecting the 60 pellets was connected to the negative end of one power supply. A stainless steel crucible 56 for maintaining the molten electrolyte 58 was connected by a second wire 62 to the other end of the power supply. The two positive ends of the two power supplies were both connected to a graphite rod anode 52. All electrical connections from individual electrodes to the power supply were made by Kanthal® wires 50,62. Electrolyte temperature was measured using a K-type thermocouple in an alumina sheath 54. The cell was placed in a vertical Inconel® reactor tube with one end closed.
[0039]
The electrolysis cell was flushed with high purity argon while heating to the required temperature. When the cell reaches its electrolysis temperature, the graphite rod anode is immersed in the molten electrolyte and pre-electrolysis is performed until U anode bubbles are no longer visually observed (typically for a period of 12 hours). _Two = 2.8-3.0V and 1173K. After completing the pre-electrolysis, the oxide cathode was immersed in the melt. The electrolysis was performed by applying a constant voltage (U) to each of the cells as shown in FIG. ₁ And U _Two ). Applied voltage (U ₁ ) (With the resulting current) were displayed and logged by a PC equipped with an ADAMS 4017-8 channel Analog-to-Digital Converter plus a Serial RS232 during the course of the electrolysis. ).
[0040]
An as-reduced sample was quickly removed from the melt under a flow of argon at 873K, quenched and washed in cold water, soaked in acid, rinsed with water, and washed with acetone. . The resulting porous pellets were pulverized by manual grinding. The resulting niobium metal powder was then washed again with acetone and dried at room temperature under vacuum.
[0041]
The morphology of the sintered or reduced pellets was observed using a Jeol JSM-5800LV scanning electron microscope with an energy dispersive X-ray analysis (EDXA) accessory. The impurity concentration was measured by EDXA. The various phases present in the prepared powder are ₁ Tested by powder X-ray diffraction (XRD) using a Philips diffractometer PW1710 with radiation. The oxygen content is also determined by weighing the niobium metal powder prepared before and after reoxidation in air, where the Nb of the metal powder is determined. _Two O _Five Complete reoxidation to was confirmed by XRD analysis. The level of chlorine in the off-gases was monitored using a Drager QuadGard Chlorine Detector.
[0042]
The final product remaining on the cathode after electrolysis was found to be niobium metal in the form of porous pellets. 9 and 10 illustrate the U ₁ = 3.1 V and 24 hours before electro-deoxidation at 1123 K (particle size 4.03 μm Nb) _Two O _Five About) and after Nb _Two O _Five 1 shows a representative microstructure of a cross section of a pellet. After reduction, it is interesting to observe that the morphology of the reduction product is essentially a powder compact sintered together and sintered to some extent, and the particle size has increased to some extent. The prepared niobium metal powder contained 2311 ppm by mass of oxygen.
[0043]
A representative measured XRD (X-ray diffraction) pattern is shown in FIG. 12 for a niobium metal powder reduced at 1173 K for 48 hours, from which one skilled in the art will recognize that the powder is pure niobium and any oxidation It can be understood that there is no physical condition.
[0044]
Overall, the results of this experiment show that Nb _Two O _Five Provides evidence that the porous pellets can be easily deoxygenated into niobium metal. The prepared niobium metal powder is clearly acceptable for subsequent purification processing (eg, high vacuum sintering at high temperatures). According to our experiments, various ranges of the particle size of the niobium metal powder can be controlled by appropriate control of the experimental conditions and by Nb _Two O _Five It has been shown that it can be easily prepared by changing the particle size of the powder.
[Brief description of the drawings]
[0045]
FIG. 1 shows an apparatus for electro-deoxidation of metal oxide powder according to a first embodiment of the present invention.
FIG. 2 shows an apparatus according to a second embodiment of the present invention.
FIG. 3 is a photomicrograph of a titanium oxide powder as used as a starting material in Examples 1 and 2.
FIG. 4 is a photomicrograph of titanium powder produced from the oxide of FIG. 3 in Example 1.
FIG. 5 is a photomicrograph of titanium powder produced from the oxide of FIG. 3 in Example 2.
FIG. 6 is a photomicrograph of a chromium powder as produced in Example 3.
FIG. 7 shows AlNi as produced in Example 5. _Three It is a microscope picture of a powder.
FIG. 8 is a schematic diagram of AlNi. _Three 8 is an XRD (X-ray diffraction) spectrum for the powder of FIG.
FIG. 9 is a photomicrograph of a niobium oxide powder, such as used as a starting material in Example 6.
FIG. 10 is a photomicrograph of niobium powder as produced in Example 6 from the oxide powder of FIG.
FIG. 11 is a schematic diagram of an apparatus for electro-deoxidation as used in Example 6.
FIG. 12 is a plot of an XRD analysis of niobium powder produced as in Example 6.

Claims (36)

The following steps:
Electrodeoxidation of a precursor powder containing a compound (M ¹ X) between a metal (M ¹ ) and a non-metal species (X) under conditions such that the non-metal species dissolves in the melt. treated (electro-deoxidation) by the precursor powder may form a cathode in contact with the melt containing molten salt (M ² Y); and, optionally electro - processed products deoxy retardation, metal A method for producing a metal powder, comprising forming a powder. Electro - deoxy retardation is carried out under conditions that lower the cathode potential than the potential for the precipitation from the melt of the cation (M ²⁾ is applied to the cathode, the method according to claim 1. Melt comprises a mixture of salts (including two or more cations (M ^2)), and Electro - deoxy retardation is lower cathode potential than the potential for the precipitation from the melt of any cations (M ²⁾ The method according to claim 1, wherein the reaction is carried out under conditions applied to the cathode. The method according to claim 1, 2 or 3, wherein the precursor powder is a conductor and is used as a cathode. The method of claim 1, 2 or 3, wherein the precursor powder is an insulator and is used in contact with the conductor to form a cathode. The method according to any of the preceding claims, wherein the electro-deoxidation is performed at a temperature of 700-1000C. The method according to any of the preceding claims, wherein the precursor powder comprises particles of a size between 0.05 and 20 [mu] m. The method according to any of the preceding claims, wherein the precursor powder comprises particles of a size between 0.25 and 2 [mu] m. The method according to any of the preceding claims, wherein the metal powder comprises particles of a size between 1 and 30 [mu] m. Ca molten salt as the cation species (M ^2), including Ba, Li, and Cs and / or Sr, A method according to any preceding claim. The method according to any of the preceding claims, wherein the molten salt comprises Cl or F as an anion (Y). The method according to any of the preceding claims, wherein the non-metallic species comprises O, S, C or N. The metal (M ¹ ) is Ti, Si, Ge, Zr, Hf, Sm, U, Al, Mg, Nd, Mo, Cr or Nb, V, Ta, Mb, W, Mn, Tc, Re, Fe, Ru, Any of the preceding claims comprising Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Be, Sr, Ga, In, Tl, lanthanides or actinides, or alloys thereof. the method of. The precursor powder is formed into a sample for electro-deoxidation by a powder processing technique (eg, slip-casting or compaction) and the product of electro-deoxidation is ground or crushed to form a metal powder. A method according to any of the preceding claims. 15. The method of claim 14, wherein forming the precursor powder comprises sintering. A method according to any of the preceding claims, wherein the precursor powder comprises a mixture or solid solution of one or more metal compounds and, optionally, one or more metals or alloys. Metal powder produced according to a method as described in any of the preceding claims. Apparatus for performing the method according to any of the preceding claims. The following steps:
Forming a metal seed compound between (X) (M ¹ X) shaped precursor from powdered feed material comprising (shaped precursor) - metal (M ¹⁾ and the non;
Treating the precursor by electro-deoxidation (the precursor comprises a molten salt (M ² Y) under conditions such that the non-metallic species dissolve in the melt; Electrodeoxidation forms an interconnect between the metal powder particles produced by electrodeoxidation, and a product close to a network shape that is strong enough for further processing. Done for a long enough time and / or at a sufficiently high temperature to produce)
And a method for forming a product having a shape close to a mesh. Electro - deoxy retardation is carried out under conditions where a low cathode potential than the potential for the precipitation from the melt of the cation (M ²⁾ is applied to the cathode, the method according to claim 19. Melt comprises a mixture of salts (including two or more cations (M ^2)), electro - deoxy retardation is lower cathode potential than the potential for the precipitation from the melt of any cations (M ²⁾ 20. The method according to claim 19, wherein the method is performed under conditions in which is applied to the cathode. 22. The method according to claim 19, 20 or 21, wherein the precursor is a conductor and is used as a cathode. 22. The method of claim 19, 20 or 21, wherein the precursor powder is an insulator and is used in contact with the conductor to form a cathode. 24. The method according to any of claims 19 to 23, wherein the electro-deoxidation is performed at a temperature of 700-1000 <0> C. 25. The method according to any of claims 19 to 24, wherein the powdered feed comprises particles of a size between 0.05 and 20 [mu] m. 25. The method according to any of claims 19 to 24, wherein the powdered feed comprises particles of a size between 0.25 and 2 [mu] m. Ca molten salt as the cation species (M ^2), including Ba, Li, and Cs and / or Sr, the method according to any of claims 19 26. 28. The method according to any of claims 19 to 27, wherein the molten salt comprises Cl or F as the anionic species (Y). 29. The method according to any of claims 19 to 28, wherein the non-metallic species comprises O, S, C or N. The metal (M ¹ ) is Ti, Si, Ge, Zr, Hf, Sm, U, Al, Mg, Nd, Mo, Cr, Nb, V, Ta, Mb, W, Mn, Tc, Re, Fe, Ru, 30. Any of claims 19 to 29 comprising Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Be, Sr, Ga, In, Tl, lanthanide or actinide, or alloys thereof. The described method. 31. The method according to any of claims 19 to 30, wherein the powdered feed is formed into a sample for electro-deoxidation by slip-casting or compaction. 32. The method according to any of claims 19 to 31, wherein forming the precursor comprises sintering. 33. A method according to any of claims 19 to 32, wherein the powdered feed comprises a mixture or solid solution of one or more metal compounds and, optionally, one or more metals or alloys. 34. The method according to any of claims 19 to 33, wherein the product close to the network shape is subsequently processed by sintering and / or machining. A near net-shaped product formed by a method as claimed in any one of claims 19 to 34. An apparatus for producing a product close to the mesh shape according to claim 35.

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