The way to obtain alloy powder of a valve metal

 

The invention relates to ferrous metallurgy and can be used to obtain alloy powders of tantalum or niobium. In the proposed method, including accommodation in a reaction vessel having a gas atmosphere, the connection of a valve metal and the halide of the alkali metal, the formation of the melt by heating and stirring, the introduction into the reaction vessel an alkali metal with the restoration of a valve metal, cooling the melt crystallization, extraction of water, its crushing, washing powder of a valve metal and the introduction of alloying additives according to the invention the recovery of a valve metal lead in the temperature interval 550-900With, and alloying additive is introduced into the gas atmosphere in the reaction vessel, and the additive is introduced from the beginning of the melt formation. Provided the magnitude of the surface of the powder 1.5-2.5 times, charge 2-3 times, reducing leakage currents in 1.2 to 3.5 times, and simplify the process of obtaining powder, reducing the duration of the method and its intensity. 8 C.p. f-crystals, 1 table.

The invention relates to ferrous metallurgy and can be used to obtain powders of tantalum and n is e them in the form of powders for the production of anodes texturized capacitors, which are characterized by such parameters as the amount of capacitance and leakage current. These parameters depend on the quality of the powder of a valve metal and process of manufacturing anodes capacitors. The anodes are usually made by pressing powder of a valve metal and sintering in the furnace followed by the application of an oxide dielectric film polarization in solutions. The quality of the powder is determined by the value of its surface and chemical composition, as the capacity of the anode of the capacitor at a given voltage proportional to the magnitude of its surface, and the content of metallic and nonmetallic impurities in excess of the maximum allowable level, causes degradation of the dielectric film, which leads to increased leakage current. In the production of capacitors, typically use a powder of a valve metal with a large value of the surface. These powders usually get metallothermic recovery. Increasing the surface of the powders can be achieved by alloying in the process of obtaining. Alloying additives also contribute to the preservation of the surface of the powders during sintering and the sintering and stabilize the electrical characteristics of the capacitor. A method of obtaining legirovaniya valve metal composition R2MX7(where R is alkali metal, M is tantalum or niobium, X is fluorine or chlorine), salts of boron, mostly in the form of tetrafluoroborate potassium KBF4in the amount of 0.5 wt.% with respect to the metal component of the valve metal in the compound R2MX7and diluent in the form of a halide of an alkali metal, the melting of the salt mixture and the introduction of the alkali metal in the resulting melt of the reactants with continuous stirring of the melt with the restoration of a valve metal, an alkaline metal. The reaction mass is then cooled to room temperature, pulverized and washed obtained powder of a valve metal from other salts. The doping can be carried out by introducing into the mother solution used for the crystallization of compounds R2MX7, orthoboric acid, H3IN3when the ratio of boron to the tantalum or niobium of 0.0005-0.5 wt.%, or by the introduction of finely dispersed amorphous boron powder in the powder of a valve metal before pressing.

The disadvantage of this method is that the obtained powders have a relatively low specific surface area, and obtained from them anodes - low specific capacity (14920 µc/g when the sintering temperature 1600Also known is a method of obtaining the doped powder of a valve metal (see U.S. Pat. U.S. NO. 4544403, N. CL 75/05 AB, 1985), involving the introduction of a tantalum salts and alkali metal halide in a reaction vessel having a protective argon atmosphere, the melting of the reactants at an elevated temperature and recovering tantalum alkaline metal in the melt mixing of the reagents. At the same time as the alkali metal halide using sodium chloride as the alkali metal is sodium. The resulting reaction mass is then cooled to room temperature, pulverized, washed powder of tantalum from accompanying salts and conduct doping it with phosphorus, carbon, nitrogen, or sulfur. This is prepared in distilled water solutions of potassium thiocyanate KCNS, thiocyanate ammonium NH4CNS, monohydrogenphosphate ammonium (NH4)2HPO4or mixtures thereof. These solutions impregnate �chr/176.gif">C. Then, the powder is heated in vacuum at a residual pressure of 10-7PA to a temperature of 1450C, kept at this temperature for 0.5 h, cooled, first in vacuum for 2 h, and then in an atmosphere of argon to room temperature, ground and sieved. The optimum values of concentrations of alloying elements in tantalum powder amount, wt.%: phosphorus is 0.0002 to 0.04, the amount of carbon, nitrogen and sulfur 0,0181-0,163. When this leakage currents do not exceed 0,001 µa/µc.

The disadvantage of this method is that the obtained powders have a relatively low specific surface area and correspondingly low specific capacity manufactured from them anodes (20730 µc/g when the sintering temperature 1400C) despite the fact that the doping contributes to the conservation values of the surface during sintering. In addition, the procedure for alloying of a valve metal after its recovery is relatively complex and requires additional energy consumption for vacuum creation and implementation of a high-temperature heating to 1450C.

The present invention is directed to solving the problems of improving the quality of the powder of a valve metal at the expense of the increase is solved by that way to obtain alloy powder of a valve metal, including accommodation in a reaction vessel having a gas atmosphere, the connection of a valve metal and the halide of the alkali metal, the formation of the melt by heating and stirring, the introduction into the reaction vessel an alkali metal with the restoration of a valve metal, cooling the melt crystallization, extraction of water, its crushing, washing powder of a valve metal and the introduction of alloying additives according to the invention the recovery of a valve metal lead in the temperature interval 550-900With, and alloying additive is introduced into the gas atmosphere in the reaction vessel, and the additive is introduced from the beginning of the melt formation.

The problem is solved also by the fact that the alloying additive is introduced into the gas atmosphere in the reaction vessel prior to the completion of solidification of the melt.

The problem is solved also by the fact that the gas atmosphere in the reaction vessel consists of argon, helium or mixtures thereof.

The problem is solved and the fact that before cooling, the melt is subjected to aging for 0.5 to 1.5 hours

Solving tasks directed that the quality of the connection ventile, as the alkaline metal is used, the sodium, potassium or a mixture thereof.

Solving tasks directed that as the halide of the alkali metal used chloride and/or fluoride.

On the solution of the problem sent and the fact that the alloying additive is introduced in the form of inorganic and/or organic compounds comprising one or more elements selected from the group consisting of phosphorus, nitrogen, sulfur, carbon in an amount to provide the content of additives in the valve metal of 0.0005 to 0.3 wt.% in terms of alloying elements.

The task contributes to the fact that the alloying additive additionally contains oxygen.

The interaction between the reagents in the reaction vessel in the temperature interval 550-900With improving quality alloyed powder of a valve metal. When the temperature drops below 550With will be partial crystallization of the melt and result in incomplete recovery of the salt of a valve metal, which leads to the formation of poorly soluble salts, complicating the washing of the obtained powder of a valve metal salts. The presence of such salts leads to increased leakage currents in gotov its specific surface. In addition, the excess of temperature above 900With the recovery process leads to increased diffusion interaction between the walls of the reaction vessel, on the one hand, and melt and salt pairs above the melt, on the other hand, and thereby causing contamination of the powder of a valve metal metallic components present in the material of the vessel.

The introduction of the alloying additives in the gas atmosphere in the reaction vessel eliminates the additional step of doping, slows the growth of crystals in the recovery process connection valve metal of the alkali metal and thereby provides an increase of the specific surface of the powder while simplifying the method and its intensity.

The introduction of alloying with the early formation of the melt reduces the time of its contact with the walls of the reaction vessel and thereby reduce contamination of the powder of a valve metal metallic components present in the material of the vessel.

The introduction of the alloying additives in the gas atmosphere in the reaction vessel prior to the completion of solidification of the melt contributes to the quality of the powder of a valve metal due to ensure the ohms to complete the crystallization of the melt may vary as quality, and quantitative composition of the additive within the specified parameters.

The presence in the gas atmosphere of the reaction vessel argon, helium or mixtures thereof allows by dissolving them in a specified number of alloying elements to provide the desired content of the alloying element in the valve metal. In addition, the gas atmosphere limits the diffusion interaction of alloying with the walls of the reaction vessel and thereby reduce contamination of the powder of a valve metal metallic components present in the material of the vessel. Exposure of the melt prior to cooling for 0.5-1.5 h provides additional surface alloying particles of a valve metal and thereby contributes to the quality of the powder by preserving its specific surface area at high temperature sintering in the process of manufacturing anodes capacitors.

The use of fortuntate or tornalate potassium as the connection of a valve metal according to the proposed method allows to obtain a powder of a valve metal with a large specific surface. Along with tortenelem or floribama potassium as the connection of a valve metal can be isplacene of fortuntate or tornalate sodium is higher compared to the cost of fortuntate and tornalate potassium, and pentachloride tantalum and niobium have a relatively low boiling point (respectively 242 and 250C) and therefore, when the temperature of the recovery will have a high vapor pressure. In addition, they are hygroscopic.

The use of sodium, potassium or mixtures thereof as alkali metal allows you to get after you restore a mixture of salts, are well soluble in water, which contributes to obtaining a powder having a low content of alkali metals. Along with sodium and/or potassium as the alkali metal can be used as lithium, rubidium and cesium, and mixtures thereof. However, after the recovery of lithium, a mixture of lithium to caesium and/or rubidium form less soluble salts, which makes washing the obtained powder of a valve metal. Recovery of cesium also allows to obtain a mixture of salts, are well soluble in water. However, cesium compared to sodium and potassium is a more expensive material that will lead to a significant increase in the cost of the finished product.

The use of a halide of an alkali metal chloride and/or fluoride reduces the melting point of the reactants and wescast what about the metal, it helps to get quality powder with a developed surface. Along with chloride and/or fluoride as the halide of the alkali metal can be used bromide and/or iodide. However, compared chlorides and fluorides they are more expensive reagents that will lead to a significant increase in the cost of the finished product. Therefore, for effective regulation of the melting temperature of the melt is preferred the use of chlorides and fluorides.

Use as alloying additives of inorganic and/or organic compounds comprising one or more elements selected from the group consisting of phosphorus, nitrogen, sulfur, carbon, improves the quality of the powder of a valve metal by increasing its specific surface area.

The introduction of the alloying additive in an amount to provide its contents into the valve metal of 0.0005 to 0.3 wt.%, helps to increase the surface of the powder and hence increased product quality. The introduction of the alloying additive in an amount to provide its contents into the valve metal is less of 0.0005 wt.%, no significant effect on the sintering process of the anode and therefore saivaism its contents into the valve metal more than 0.3 wt.%, causes degradation of the dielectric film, thus reducing the quality of the powder due to a significant increase leakage currents.

The use of oxygen in the composition of the alloying additives contributes to the quality of the powder of a valve metal by increasing its specific surface area due to the increase in the number of crystallization centers and passivation of the edges of the powder particles, resulting in the recovery process of a valve metal. The content of oxygen in the source powder may exceed 0.3 wt.%. In this case, to bring the oxygen concentration in accordance with the established limits of the content of alloying elements after washing powder of a valve metal from related salts it is dried, mixed with magnesium is heated to a temperature of 750-1000With in a closed metal crucible in an argon atmosphere, maintain 0.5 to 2.5 hours, cooled and washed the powder of a valve metal from the remnants of magnesium in the solution of mineral acid. This operation due to the high affinity of magnesium to oxygen provides a solid refinement of a valve metal. The decrease in powder oxygen content in the solid phase refining contributes coord is m if the way to obtain alloy powder of a valve metal according to the invention is as follows. In a cylindrical reaction vessel loads the connection of a valve metal K2MF7(where M is tantalum or niobium) and the diluent in the form of a halide of an alkali metal MeR (where Me is sodium, potassium, R is chlorine, fluorine). Then the reaction vessel vacuum to a pressure of 1-3 PA, filled with inert gas (argon or helium), is heated to a temperature of 550-800If valve metal is niobium, or 580-800If the valve metal is tantalum. Are holding at that temperature for 0.5 to 1.5 hours Then at any period of time from the beginning of the formation of the melt until the completion of its crystallization in the gas atmosphere in the reaction vessel enter the alloying additive in the form of inorganic and/or organic compounds comprising one or more elements selected from the group consisting of phosphorus, nitrogen, sulfur, carbon, and oxygen. The amount of alloying in the gas atmosphere is controlled within the specified limits. In this variant, in which the gas atmosphere of the reaction vessel is made from 100% alloying additives, for example, pure nitrogen or nitrogen mixed with oxygen.

After the introduction of the alloying additives in the gas atmosphere in the reaction vessel pushem stoichiometric quantity needed for full recovery of a valve metal. In the recovery process in the reaction vessel to maintain the temperature above the melting point of the melt. This is followed by cooling of the melt, which is accompanied by its crystallization. Before cooling, the melt may be subjected to exposure for 0.5 to 1.5 hours At room temperature is reached, the melt is removed from the reaction vessel, pulverized and the resulting powder of a valve metal is rinsed in water from other salts. Washed from salt powder is treated consistently in a 10% Hcl solution and 1% HF aqueous solution, which take, respectively, in the amount of 1.0 and 0.5 l/kg powder, washed thoroughly with distilled water and dried. Specific surface area of the obtained powder was measured by the method of thermal desorption of argon. Present in the valve metal alloying additive in the form of nitrogen and oxygen is determined by pulsed heating on the analyzer K-671, and the carbon, sulfur and phosphorus - automatic coulometric titration Express analyzer an-75-29.

As the inorganic compounds can be advantageously used: nitrogen (N2oxygen O2yellow phosphorus P4ammonia NH3, thio-phospholipid PS(NH2)3, trichloride phosphorus l4isothiocyanatomustard phosphorus PF2CNS and isothiocyanate phosphorus PF(CNS)2.

The criterion for the choice of the alloying additive is its explosion and the restriction in relation to the boiling temperature (TKip.or decomposition temperature (Tdifferent.) gas components, including the alloying element. It boils down to the fact that these temperatures should not exceed 550In the case of obtaining a niobium powder and 580In case of receipt of tantalum powder. The alloying additive is introduced into the atmosphere of the reaction vessel in the volume ratio, providing its contents into the valve metal of 0.0005 to 0.3 wt.% in terms of alloying elements. The value of the specific mass transfer alloying elements from the gas phase into the liquid phase is proportional to its solubility in the melt. In stationary conditions, the change in the concentration of the alloying additives in the melt at saturation is given by the equation

C=Cabout[1-exp(-kt/l)],

where Cabout- the equilibrium concentration of alloying elements in the melt,

k is a constant mass transfer,

t - time,

l is the height of the melt in the reaction vessel.

At this important stage of saturation of the melt alloying additive is its diffusion in of valve metal will occur uniformly throughout the volume of the melt, regardless of the location of the reagents within the reaction vessel.

Technological testing of powders is done according to generally accepted industry methods. From the resulting powder is pressed anodes with a diameter of 2.95 mm and a density of 4.5 g/cm3. The anode is sintered in vacuum resistance furnace at a residual pressure of not more than 510-5PA and a temperature of 1400C. the dwell time at maximum temperature is 30 minutes Forming anodes is carried out at a temperature of 80With a 1% solution of phosphoric acid to achieve a voltage of 70 V At a constant current density of 60 mA/g, and then at a constant voltage for 3 hours capacity Measurement is carried out in 38% sulfuric acid with the help bridge the ITRS-8 at a frequency of 50 Hz. The leakage current is determined at the voltage of 0.75 from the forming voltage.

The nature and advantages of the invention can be illustrated by the following examples of embodiment of the invention.

Example 1. In a cylindrical reaction vessel having a height of 400 mm and an inner diameter of 260 mm, a load of 10.0 kg salt K2TaF7and 5.0 kg of salt NaCl. After loading the reagent vessel vacuum to a pressure of 2 PA, filled with argon, heated to 600°C and maintained at this temperature for 1H -196When the volume ratio of Ar:N2=5:3. After that, the temperature of the melt is reduced to 580With and within 1.3 hours with continuous stirring served on the melt surface of the liquid sodium in the number is 3.08 kg While the melt temperature gradually increased to 820C. Thus, the recovery of tantalum lead in the temperature interval 580-820After exposure at 820C for 1.5 h carry out the cooling of the melt crystallization. Upon reaching room temperature, the melt is removed from the reaction vessel, crushed and powder of tantalum washed with water from the salts. The content in tantalum powder alloying nitrogen was 0.05 wt.%. The obtained tantalum powder had a specific charge=40800 µc/,

Main characteristics of the tantalum powder obtained in example 1, and powders of tantalum and niobium obtained in examples 2-11 and example 12 on the prototype shown in the table.

Example 2. In a cylindrical reaction vessel having a height of 260 mm and an inner diameter of 150 mm, load 3.1 kg salt K2NbF7and 2.7 kg of salt KCl. After loading the reagent vessel vacuum to a pressure of 3 PA, filled with helium, Then heated in a gas atmosphere of the vessel is injected carbon tetrachloride CCL4with TKip=76,8When the volume ratio of He:CCl4=35:1. After that, the melt temperature was lowered to 650With and within 0,6 h with continuous stirring served on the melt surface of the liquid sodium in the amount of 1.3 kg While the melt temperature gradually increased to 900C. Thus, the recovery of niobium lead in the temperature interval 650-900C. after the filing of sodium spend the cooling of the melt crystallization. Upon reaching room temperature, the melt is removed from the reaction vessel, crushed and powder of niobium washed with water from the salts. The content in the niobium powder alloying elements carbon was 0,008 wt.%. The obtained niobium powder had a specific charge=33100 µc/,

Example 3. In a cylindrical reaction vessel having a height of 200 mm and an internal diameter of 140 mm, load 3.0 kg of salt To2F7, 4.5 kg of salt NaCl, 0.5 kg of salt KF and 0.7 kg of salt KCl. After loading the reagent vessel vacuum to a pressure of 1 PA, filled with argon, heated to 810C and maintained at this temperature for 0.5 h before fusion of the mixture of salts. Then in the gas atmosphere of the vessel. the donkey that the melt temperature was lowered to 750With and for 0.5 h under continuous stirring serves on the surface of the molten liquid potassium in the number of 1.64 kg While the melt temperature gradually increased to 790C. Thus, the recovery of tantalum lead in the temperature interval 750-790C. After holding at 790C for 0.5 h carries out the cooling of the melt crystallization. Upon reaching room temperature, the melt is removed from the reaction vessel, crushed and powder of tantalum washed with water from the salts. The content in tantalum powder alloying additives phosphorus was of 0.0005 wt.%. The obtained tantalum powder had a specific charge=38500 µc/,

Example 4. In a cylindrical reaction vessel having a height of 200 mm and an internal diameter of 140 mm, load 3.0 kg salt K2NbF7, 1,92 kg of salt NaCl, 0.3 kg of salt KF, 0.12 kg of salt NaF and 0.75 kg of salt KCl. After loading the reagent vessel vacuum to a pressure of 3 PA, filled with argon, heated to 600°C and maintained at this temperature for 0.6 hours to melt a mixture of salts. Then in the gas atmosphere of the vessel to introduce sulfur dichloride SCl2with TKip=59With and within 0,6 h with continuous stirring serves on the surface of the melt liquid mixture of sodium and potassium in an amount of 1.26 kg While the melt temperature gradually increased to 760C. Thus, the recovery of niobium lead in the temperature interval 550-760C. After aging at 760C for 0.5 h hold the cooling of the melt crystallization. Upon reaching room temperature, the melt is removed from the reaction vessel, crushed and powder of niobium washed with water from the salts. The content in the niobium powder alloying additives sulfur was 0.02 wt.%. The obtained niobium powder had a specific charge=39200 µc/,

Example 5. In a cylindrical reaction vessel having a height of 400 mm and an inner diameter of 260 mm, a load of 10.0 kg salt K2TaF7, 0,10 kg of salt NaF and 12.3 kg of salt KF. After loading the reagent vessel vacuum to a pressure of 2 PA, filled with argon, heated to 840C and maintained at this temperature for 0.8 h to melting of the mixture of salts. Then in the gas atmosphere of the vessel, introducing oxygen with TKip=-183When the volume ratio of AG:O2=60:1. After that, the temperature rasti melt liquid sodium in the amount of 3.2 kg In this case, the temperature of the melt gradually increase to 860C. Thus, the recovery of tantalum lead in the temperature interval 740-860C. after the filing of sodium spend the cooling of the melt crystallization. Upon reaching room temperature, the melt is removed from the reaction vessel, crushed and washed the powder of tantalum water from salts. The content in tantalum powder alloying oxygen was 0.8 wt%. To reduce the concentration of oxygen dried powder is mixed with magnesium shavings in the amount of 0.11 kg, is heated to a temperature of 800With in a closed metal crucible in an argon atmosphere and maintained for 2.5 hours Then cooled to room temperature, removed from the metal of the crucible and washed off the residue of magnesium in 15% aqueous solution of nitric acid. After treatment with magnesium content in tantalum powder alloying oxygen was 0.3 wt.%. Received cantaloupe powder had a specific charge=70100 µc/,

Example 6. In a cylindrical reaction vessel having a height of 200 mm and an internal diameter of 140 mm, load 3.0 kg salt K2NbF7, 1.7 kg of salt NaCl and 1.3 kg of salt is KCl. After loading the reagents with the tion of 0.5 h to melting of the mixture of salts. Then in the gas atmosphere of the vessel is injected ammonia NH3with TKip=-33,5With and trichloride phosphorus l3with TKip=76When the volume ratio of No:NH3:l3=50:2:3. After that, the melt temperature increased to 730With and for 0.5 h under continuous stirring serves on the surface of the melt liquid mixture of sodium and potassium in the number of 1.39 kg While the melt temperature gradually increased to 800C. Thus, the recovery of niobium lead in the temperature interval 730-800C. After aging at 800C for 1.5 h carry out the cooling of the melt crystallization. Upon reaching room temperature, the melt is removed from the reaction vessel, crushed and powder of niobium washed with water from the salts. The content in tantalum powder alloying additives is, wt.%: nitrogen - 0,04, phosphorus - 0,006. The obtained niobium powder had a specific charge=54000 µc/,

Example 7. In a cylindrical reaction vessel having a height of 200 mm and an internal diameter of 140 mm, load 3.0 kg salt K2NbF7and 4.3 kg of salt KF. After loading the reagent vessel vacuum to a pressure of 1 PA, sampleslaya mixture of salts. Then in the gas atmosphere of the vessel, introducing gaseous oxygen at a volume ratio of Not:O2=120:1. After that, the temperature of the melt is reduced to 720With and for 0.1 h with continuous stirring served on the melt surface of the liquid sodium in the amount of 0,05 kg Continuing the stirring of the melt, stop the flow of sodium and replace a gas atmosphere consisting of a mixture of helium and oxygen, pure argon. Thereafter, in an atmosphere of argon injected gaseous nitrogen in a volume ratio of Ar:N2=9:2 and serves on the surface of the molten liquid sodium in the amount of 1.2 kg At a temperature of melt smoothly increase up to 800C. Thus, the recovery of niobium lead in the temperature interval 720-800C. After aging at 800C for 1 hour to carry out the cooling of the melt crystallization. Upon reaching room temperature, the melt is removed from the reaction vessel, crushed and powder of niobium washed with water from the salts. The content in the niobium powder alloying additives is, wt.%: oxygen - 0,29, nitrogen is 0.01. The obtained niobium powder had a specific charge=50100 µc/,

Example 8. Get doped Tanta is injected chloride tifosi Sl3with TKip=125With the volume ratio of AG:Sl3=35:1. The content in tantalum powder alloying additives is, wt.%: phosphorus is 0.07, sulfur - 0,06. The obtained tantalum powder had a specific charge=28900 µc/,

Example 9. Get doped tantalum powder of example 1. The difference is that in a gas atmosphere instead of nitrogen injected thiophosphoramide PS(NH2)3with a decomposition temperature TFS=280C in the volume ratio of AG:PS(NH2)3=40:1. The content in tantalum powder alloying additives is, wt.%: nitrogen and 0.08, phosphorus is 0.05, sulfur - 0,04. The obtained tantalum powder had a specific charge=42700 µc/,

Example 10. Get doped tantalum powder according to example 2. The difference is that in a gas atmosphere instead of carbon tetrachloride CCL4enter isothiocyanate phosphorus PF(CNS)2with TKip=of 97.8°C in a volume ratio of Ar:PF(CNS)2=30:1. The content of alloying elements in the niobium powder is, wt.%: nitrogen - 0,006, phosphorus - 0,007, sulfur - 0,011, carbon - 0,006. The obtained niobium powder had a specific charge=47300 µc/,

Example 11. Get doped tantalum powder according to example 9. The difference enters into the PF2CNS with TKip=90°and chloride thionyl SOCl2with TKip=75With the volume ratio of Ar:PF2CNS:SOCl2=60:2:1. The content in tantalum powder alloying additives is, wt.%: nitrogen - 0,005, phosphorus - 0,001, sulfur - 0,007, carbon - 0,005, oxygen - 0,12. The obtained tantalum powder had a specific charge=35800 µc/,

Example 12 (the prototype). In a cylindrical reaction vessel having a height of 400 mm and an inner diameter of 260 mm, a load of 10.0 kg salt K2TaF7and 12.5 kg of salt NaCl. After loading the reagent vessel vacuum to a pressure of 2 PA, filled with argon, heated to 800C and maintained at this temperature for 1 h before fusion of the mixture of salts. After that, the melt temperature was lowered to 700With and within 1.3 hours with continuous stirring served on the melt surface of the liquid sodium in the amount of 3.1 kg While the melt temperature gradually increased to 800C. after the filing of sodium spend the cooling of the melt crystallization. Upon reaching room temperature, the melt is removed from the reaction vessel, crushed and powder of tantalum washed with water from salts and dried. Then distilled in the m impregnate the powder of tantalum, then again dried in air. Then the powder is heated in vacuum at a residual pressure of 10-7PA to a temperature of 1450C, kept at this temperature for 0.5 h and cooled first in vacuum for 2 h, and then in an atmosphere of argon to room temperature. The content in tantalum powder alloying additives is, wt.%: phosphorus - 0,002, the amount of carbon, nitrogen and sulfur - 0,0163. The obtained tantalum powder had a specific charge=20730 µc/,

From the above examples and the table shows that the proposed method can improve the quality of the powder of a valve metal. Compared with the prototype, the size of the surface of the powder is increased in 1,5-2,5 times, its charge increases by 2-3 times, and the leakage currents are reduced 1.2-3.5 times. Furthermore, the method allows to combine the restore operation of a valve metal and its alloy, which greatly simplifies the process of obtaining powder, reduces the duration and the intensity.

Claims

1. The way to obtain alloy powder of a valve metal, including accommodation in a reaction vessel having a gas atmosphere, the connection of a valve metal and the halide of Melo is atalla with the restoration of a valve metal, cooling of the melt crystallization, extraction of water, its crushing, washing powder of a valve metal and the introduction of alloying additives, characterized in that the restoring valve metal lead in the temperature range 550-900With, and alloying additive is introduced into the gas atmosphere in the reaction vessel, and the additive is introduced from the beginning of the melt formation.

2. The method according to p. 1, wherein said alloying additive is introduced into the gas atmosphere in the reaction vessel prior to the completion of solidification of the melt.

3. The method according to p. 1 or 2, characterized in that the gas atmosphere in the reaction vessel consists of argon, helium or mixtures thereof.

4. The method according to any of paragraphs.1-3, characterized in that before cooling, the melt is subjected to aging for 0.5 to 1.5 hours

5. The method according to any of paragraphs.1-4, characterized in that the connection of the valve metal is used tortontilt or forniat potassium.

6. The method according to any of paragraphs.1-5, characterized in that the alkali metal is used, the sodium, potassium or a mixture thereof.

7. The method according to any of paragraphs.1-6, characterized in that the alkali metal halide used chloride and/or fluoride.

8. The method according to any of paragraphs.1-6, characterized in that l is of ways, selected from the group consisting of phosphorus, nitrogen, sulfur, carbon, in an amount to provide its contents into the valve metal of 0.0005 to 0.3 wt.% in terms of alloying elements.

9. The method according to p. 8, characterized in that the alloying additive additionally contains oxygen.

 

Same patents:

The invention relates to metals, in particular tantalum, and products made from tantalum, as well as to methods of obtaining and processing of tantalum

The invention relates to metallurgy tantalum production for structural products and tantalum capacitors

The invention relates to the hydrometallurgical processing of ore concentrates, and more particularly to the processing of loparite concentrate and can be used in complex extraction of compounds of titanium, niobium and tantalum
The invention relates to the hydrometallurgical processing of ore concentrates, and more particularly to the processing of loparite concentrate, and can be used in complex extraction of compounds of titanium, niobium and tantalum

The invention relates to the extraction and selective extraction of metal components, such as uranium, thorium, scandium and zirconium, from the source material, which consists of these components
The invention relates to the hydrometallurgical processing of technoeconomically concentrates, and more particularly to the opening of loparite concentrate

The invention relates to the recovery of metal from metal-containing material

The invention relates to ferrous metallurgy and can be used to obtain high-purity powders of tantalum and niobium with a large specific surface for the production of capacitors
The invention relates to metallurgy, in particular, to obtain granules and powders of rare and radioactive metals and their alloys

The invention relates to ferrous metallurgy and can be used to obtain high-purity powders of tantalum and niobium with a large specific surface for the production of capacitors

The invention relates to powder metallurgy and can be used to obtain high-purity powders of tantalum and niobium with a large specific surface for the production of capacitors
The invention relates to the field of powder metallurgy and concerns a method for obtaining powders of refractory compounds on the basis of a carbide or nitride of titanium compounds that can be used for the production of cutting tools, metal fittings, etc

The invention relates to the production of powders of refractory metals and can be used in enterprises: non-ferrous metallurgy in the production of high-quality hard alloys; chemical industry for preparation of catalysts; the electronics industry in the manufacture of bodies glow and so on

The invention relates to powder metallurgy, in particular to the manufacture of powders based on iron, and can be used in chemical industry and medicine

The invention relates to ferrous metallurgy, in particular to obtain a powder of alloys based on titanium metals, soluble in liquid magnesium, metallothermic recovery of titanium chloride (IV)

The invention relates to powder metallurgy, in particular the production of highly dispersed iron powder materials having a high surface activity and used as biologically active agents or catalysts

FIELD: non-ferrous metallurgy, possibly production of highly purified powders of tantalum and niobium with large specific surface by metal thermal reduction.

SUBSTANCE: method is realized at using as corrosion protection means layer of halide of alkali metal formed on inner surface of vessel before creating in reaction vessel atmosphere of inert gas. Charge contains valve metal compound and halide of alkali metal. It is loaded into reaction vessel and restricted by protection layer of halide of alkali metal having melting temperature higher than that of charge by 50 - 400°C. Before loading charge, valve metal compound and alkali metal halide may be mixed one with other. Mass of protection layer of alkali metal halide Ml and charge mass Mc are selected in such a way that that to satisfy relation Ml = k Mc where k - empiric coefficient equal to 0.05 - 0.5. Gas atmosphere of reaction vessel contains argon, helium or their mixture. Fluorotantalate and(or) oxyfluorotantalate or fluoroniobate and(or) oxyfluoroniobate of potassium is used as valve metal compound. Sodium, potassium or their mixture is used as alkali metal. Chloride and(or) fluoride is used as alkali metal halide. Valve metal compound and alkali metal halide may contain alloying additives of phosphorus, sulfur, nitrogen at content of each additive in range 0.005 - 0.1% and 0.005 - 0.2% of mass valve metal compound respectively. Invention lowers by 1.3 - 2 times contamination of powder with metallic impurities penetrating from vessel material. Value of specific surface of powder is increased by 1.2 - 1.8 times, its charge is increased by 10 - 30 %, leakage current are reduced by 1.2 - 1.5 times.

EFFECT: improved quality of valve metal powder, enhanced efficiency of process due to using heat separated at process of reducing valve metal for melting protection layer.

9 cl, 1 tbl, 4 ex

Up!