CN105855561B - Preparation method of superfine/nano tantalum-tungsten composite powder and superfine/nano tantalum-tungsten composite powder prepared by same - Google Patents
Preparation method of superfine/nano tantalum-tungsten composite powder and superfine/nano tantalum-tungsten composite powder prepared by same Download PDFInfo
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- B—PERFORMING OPERATIONS; TRANSPORTING
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- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/16—Making metallic powder or suspensions thereof using chemical processes
- B22F9/18—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
- B22F9/20—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from solid metal compounds
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- B—PERFORMING OPERATIONS; TRANSPORTING
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- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
- B22F1/05—Metallic powder characterised by the size or surface area of the particles
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- B—PERFORMING OPERATIONS; TRANSPORTING
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- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/16—Making metallic powder or suspensions thereof using chemical processes
- B22F9/18—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
- B22F9/20—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from solid metal compounds
- B22F9/22—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from solid metal compounds using gaseous reductors
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Abstract
The invention provides a preparation method of superfine/nano tantalum-tungsten composite powder, which takes a tantalum fluoride acid solution and tungstate as raw materials, and comprises the steps of adding tungstate powder in a calculated amount into the tantalum fluoride acid solution, adding a surfactant to prepare a sol solution, adding an alkaline precipitator until the pH value is 9-12, and precipitating to obtain tantalum-tungsten precursor composite powder; and then hydrogen reduction, alkali metal reduction and magnesium reduction deoxidization are carried out to obtain the superfine/nano tantalum-tungsten composite powder. The invention also provides the superfine/nano tantalum-tungsten composite powder prepared by the preparation method, wherein the grain size is 10-200 nm, and the mass percent of tungsten is 2.5-70%. The superfine/nano tantalum-tungsten composite powder provided by the invention has the advantages of uniform distribution of tantalum and tungsten components and high sintering activity.
Description
Technical Field
The invention belongs to the technical field of powder metallurgy, and particularly relates to a preparation method of tantalum-tungsten composite powder and the prepared tantalum-tungsten composite powder.
Background
Tantalum-tungsten (Ta-W) alloys have the advantages of high density, high melting point, high elastic modulus, high ductility, good processability, high temperature strength, corrosion resistance, weldability, low plastic-brittle transition temperature and the like, and are widely applied to the fields of aerospace, national defense and military industry, chemical industry, nuclear industry and the like. Tungsten is added into tantalum to form solid solution type alloy, and the solid solution strengthening and grain refining effects are achieved. With the increase of the tungsten content, the performance of the tantalum-tungsten alloy at room temperature and high temperature is obviously improved.
Tantalum-tungsten alloys are generally prepared by vacuum electron beam melting and powder metallurgy. Research shows that the vacuum electron beam melting method can effectively remove various impurities in the material, particularly low-melting-point impurities. However, the ingot prepared by the vacuum electron beam melting method has large crystal grains, which is not beneficial to the subsequent processing and forming of the ingot. To refine the grains, rolling deformation and annealing treatments are generally used. However, the above-mentioned treatment has a limited effect of refining grains. In the powder metallurgy method in the prior art, tantalum powder and tungsten powder are generally mixed according to a certain proportion, then are pressed and formed to obtain a tantalum-tungsten alloy green body, and finally the alloy green body is placed in a vacuum hot-pressing sintering furnace for sintering and is cooled to obtain a tantalum-tungsten alloy green body. The method is adopted in the tungsten-tantalum alloy plate disclosed in the chinese patent application published as CN102416475A (the title of the invention is "a method for preparing a functional material tungsten-tantalum alloy plate for nuclear use", published 2012, 4-18). The tantalum-tungsten alloy prepared by the method has the advantages of longer material transmission distance among powder particles, more difficult uniform component distribution and low densification degree because the grain size of the original powder is larger, and the requirement of high performance of the material is difficult to achieve.
With the development of social economy, higher requirements are put forward on the performance of tantalum-tungsten alloy materials, and particularly, the requirements on high-performance tantalum-tungsten alloy materials in special application fields and the requirements on preparation of parts with complex shapes or micro parts by adopting a 3D printing technology are met, so that superfine/nano tantalum-tungsten composite powder is urgently needed. However, no report related to the preparation of ultrafine/nano tantalum-tungsten composite powder is found in the prior art at present.
Disclosure of Invention
Aiming at the technical problems, the invention provides a preparation method of superfine/nano tantalum-tungsten composite powder. The method of the invention prepares the superfine/nano tantalum-tungsten composite powder by using a nano in-situ composite technology. The superfine/nano tantalum-tungsten composite powder has high sintering activity, is easy to realize high densification of materials, reduces internal defects of the materials, obviously improves the machining performance of the materials, can meet higher requirements of high and new technical fields on material performance, and uses raw materials required by a 3D printing technology.
In order to achieve the technical effects, the invention adopts the following technical scheme:
a method for preparing superfine/nano tantalum-tungsten composite powder takes a fluorine-tantalum acid solution and tungstate as raw materials, and comprises sol-coprecipitation, hydrogen reduction, alkali metal reduction and magnesium reduction deoxidization; adding tungstate powder in a calculated amount into the fluotantalic acid solution, adding a surfactant to prepare a sol solution, adding an alkaline precipitator until the pH value is 9-12, preferably 9-10, and precipitating to obtain the tantalum-tungsten precursor composite powder.
Preferably, the content of the fluotantalic acid solution is 20-120 g/L calculated by tantalum oxide, and the HF concentration is 0.3-1.5 mol/L.
Preferably, the tungstate is selected from ammonium paratungstate (5 (NH)4)2O·12WO3·5H2O) or ammonium metatungstate, more preferably ammonium paratungstate, with a purity of 88.5% or more.
Preferably, the surfactant is selected from one or more of PEG-400, PEG-600, PEG-1000 and PEG-2000; more preferably PEG-600.
Preferably, the dosage (volume) of the surfactant is 0.1-3% of the volume of the tantalum fluoride acid solution; more preferably 0.5%.
Preferably, the alkaline precipitant is selected from aqueous ammonia, sodium hydroxide, potassium hydroxide or ammonium bicarbonate; more preferably aqueous ammonia.
Preferably, in the sol-co-precipitation step, after the alkaline precipitant is added, standing, aging, suction filtering, washing and drying are further included.
Preferably, the standing and aging time is 20 minutes to 4 hours, more preferably 0.5 hour.
Preferably, washing the precipitate obtained after suction filtration with ammonia-bubbling hot pure water until the fluorine mass percentage content (F%) < 0.5%; the ammonia concentration of the drum ammonia hot pure water is 0.1-1 mol/L, and more preferably 0.3 mol/L; the temperature of the ammonia-blowing hot pure water is 40-90 ℃, and more preferably 70-80 ℃.
Preferably, in the sol-coprecipitation step, the drying device is a hot air circulation oven, the drying temperature is 60-200 ℃, and the drying time is 2-10 hours.
More preferably, in the sol-coprecipitation step, the drying device is a hot air circulation oven, the drying temperature is 110-130 ℃, and the drying time is 4 hours.
As a preferred embodiment, the specific operation of the sol-coprecipitation step is:
firstly, adding calculated amount of ammonium paratungstate or ammonium metatungstate powder into a fluotantalic acid solution, then adding PEG-600 with the volume of 0.5 percent of the fluotantalic acid solution, and stirring to prepare a sol solution; then slowly adding ammonia water (precipitant) to a pH value of 9-10 under ultrasonic oscillation or stirring, standing and aging for 0.5 hour, detecting and adjusting the pH value of the solution to the pH value before standing, and performing suction filtration; washing the precipitate with ammonia-blowing hot pure water with ammonia concentration of 0.3mol/L at 70-80 ℃ until the fluorine mass percentage content (F%) is less than 0.5%; placing the washed precipitate in a hot air circulation oven, and drying for 4 hours at 110-130 ℃ to obtain tantalum-tungsten precursor composite powder; wherein the content of the fluotantalic acid solution is 20-120 g/L in terms of tantalum oxide, and the HF concentration is 0.3-1.5 mol/L.
Preferably, in the hydrogen reduction step, the tantalum-tungsten precursor composite powder obtained in the sol-coprecipitation step is heated to 600-1000 ℃ in one or more steps in a hydrogen atmosphere, and the temperature is maintained for 0.5-3 hours to obtain the tantalum oxide-tungsten composite powder.
More preferably, in the hydrogen reduction step, the tantalum-tungsten precursor composite powder is heated to 850-900 ℃ in one or more steps under a hydrogen atmosphere, and the temperature is maintained for 1 hour, so that the tantalum oxide-tungsten composite powder is obtained.
Preferably, in the hydrogen reduction step, the tantalum-tungsten precursor composite powder is further heated to 850-900 ℃ in a hydrogen atmosphere, and the temperature is maintained for 1 hour, so that the tantalum oxide-tungsten composite powder is obtained.
Preferably, in the alkali metal reduction step, the tantalum oxide-tungsten composite powder obtained in the hydrogen reduction step is subjected to co-reduction by alkali metal sodium and two or more chlorides selected from calcium chloride, potassium chloride, sodium chloride and magnesium chloride at 600-1000 ℃, and the heat preservation time is 1-6 hours; then pure water washing, acid washing and hot pure water washing are carried out, and tantalum (or tantalum hydride) -tungsten composite powder is obtained after drying; wherein the mass ratio of sodium to tantalum oxide is 0.2-0.8: 1, and the mass ratio of chloride to tantalum oxide is 1.2-2.5: 1.
More preferably, in the alkali metal reduction step, the reduction temperature is 900 to 950 ℃, and most preferably 920 ℃.
More preferably, in the alkali metal reduction step, the holding time is 4 hours.
More preferably, in the alkali metal reduction step, the mass ratio of sodium to tantalum oxide is 0.6: 1.
More preferably, in the alkali metal reduction step, the chloride is selected from two or more of calcium chloride, potassium chloride and sodium chloride.
More preferably, the mass ratio of the calcium chloride, the potassium chloride and the sodium chloride to the tantalum oxide is 1.6: 1.
More preferably, the pure water washing is normal-temperature pure water washing, and the washing end point is the solution conductivity less than 50 mu s/cm.
More preferably, the washing agent for acid washing is selected from one or more of nitric acid, hydrochloric acid and sulfuric acid, the volume percentage concentration of the acid is 10-60%, and the end point of the acid washing is that the conductivity of the solution is less than 30 mus/cm.
Further preferably, the acid-washing detergent is nitric acid with a concentration of 40% by volume.
More preferably, the hot pure water washing is carried out by washing with hot pure water at 40-90 ℃ until the solution conductivity is less than 20 mu s/cm.
Further preferably, the temperature of the hot pure water is 70-80 ℃.
More preferably, in the step of reducing the alkali metal, the drying device is a vacuum oven, the drying temperature is 60-120 ℃, and the drying time is 4-12 hours. More preferably, the drying temperature is 80-100 ℃, and the drying time is 8-10 hours.
As a preferred embodiment, the alkali metal reduction step of the present invention is specifically performed by:
reducing the tantalum oxide-tungsten composite powder obtained in the hydrogen reduction step by using alkali metal sodium, calcium chloride, potassium chloride and sodium chloride at 900-950 ℃, and preserving the heat for 4 hours; wherein the mass ratio of sodium to tantalum oxide is 0.6: 1, and the mass ratio of chloride to tantalum oxide is 1.6: 1; after the reduced product is cooled, washing the solution with normal-temperature pure water until the conductivity of the solution is less than 50 mu s/cm, then washing the solution with 10-60% by volume of one of nitric acid, hydrochloric acid and sulfuric acid until the conductivity of the solution is less than 30 mu s/cm, and finally washing the solution with hot pure water at 40-90 ℃ until the conductivity of the solution is less than 20 mu s/cm; and (3) placing the washed powder in a vacuum oven, and drying for 4-12 hours at the temperature of 60-120 ℃ to obtain the tantalum (or tantalum hydride) -tungsten composite powder.
As a more preferred embodiment, the alkali metal reduction step of the present invention is specifically performed by:
reducing the tantalum oxide-tungsten composite powder obtained in the hydrogen reduction step by using alkali metal sodium, calcium chloride, potassium chloride and sodium chloride at 920 ℃, and preserving the temperature for 4 hours; wherein the mass ratio of sodium to tantalum oxide is 0.6: 1, and the mass ratio of chloride to tantalum oxide is 1.6: 1; after the reduced product is cooled, washing the product with normal-temperature pure water until the conductivity of the solution is less than 50 mu s/cm, washing the product with nitric acid with the volume percentage of 40% until the conductivity of the solution is less than 30 mu s/cm, and finally washing the product with hot pure water at the temperature of 70-80 ℃ until the conductivity of the solution is less than 20 mu s/cm; and (3) putting the washed powder into a vacuum oven, and drying for 8-10 hours at the temperature of 80-100 ℃ to obtain the tantalum (or tantalum hydride) -tungsten composite powder.
Preferably, in the magnesium reduction and oxygen removal step, the tantalum (or tantalum hydride) -tungsten composite powder obtained in the alkali metal reduction step is subjected to magnesium reduction and oxygen removal for 2 to 5 hours at 800 to 1000 ℃, and more preferably subjected to magnesium reduction and oxygen removal for 2 to 3 hours at 900 to 950 ℃; and (3) carrying out acid washing, water washing and drying to obtain the superfine/nano tantalum-tungsten composite powder.
In the step of deoxidizing by reducing magnesium, preferably, magnesium powder or magnesium sheets are adopted; more preferably magnesium flakes.
In the step of deoxidizing by reducing magnesium, the mass of magnesium is 8-12% of that of tantalum.
Preferably, in the magnesium reduction oxygen removal step, the pickling detergent is one or more selected from nitric acid, hydrochloric acid and sulfuric acid, and the volume percentage concentration of the acid is 10-60%; the acid washing end point is that the conductivity of the solution is less than 30 mu s/cm.
More preferably, the acid wash detergent is nitric acid with a concentration of 40% by volume.
Preferably, the detergent for water washing is selected from pure water or hot pure water at 40-90 ℃, more preferably hot pure water at 70-80 ℃, and the water washing end point is reached until the solution conductivity is less than 20 mu s/cm.
Preferably, in the step of deoxidizing by reducing magnesium, the drying device is a vacuum oven, the drying temperature is 60-120 ℃, and the drying time is 6-10 hours.
More preferably, the drying temperature is 75-90 ℃, and the drying time is 7-9 hours.
As a preferred embodiment, the specific operation of the magnesium reduction oxygen removal step in the invention is as follows:
reducing tantalum (or tantalum hydride) -tungsten composite powder obtained in the alkali metal reduction step by adopting magnesium powder or magnesium sheets at 800-1000 ℃ for deoxidizing for 2-5 hours; wherein the mass of the magnesium is 8-12% of that of the tantalum; after the reduced product is cooled, washing the product with one of nitric acid, hydrochloric acid and sulfuric acid with the volume percentage of 10-60% until the conductivity of the solution is less than 30 mus/cm, and then washing the product with pure water at the temperature of 40-90 ℃ until the conductivity of the solution is less than 20 mus/cm; and (3) placing the washed powder in a vacuum oven, and drying for 6-10 hours at the temperature of 60-120 ℃ to obtain the superfine tantalum-tungsten composite powder.
As a more preferred embodiment, the specific operation of the magnesium reduction oxygen removal step of the present invention is as follows:
reducing and deoxidizing the tantalum (or tantalum hydride) -tungsten composite powder obtained in the alkali metal reduction step for 2-3 hours at 900-950 ℃ by adopting a magnesium sheet; wherein, when the mass percent of oxygen is 2-4%, the mass of magnesium is 10% of that of tantalum; after the reduced product is cooled, washing the product with nitric acid with the volume percentage of 40% until the conductivity of the solution is less than 30 mus/cm, and then washing the product with pure water at the temperature of 70-80 ℃ until the conductivity of the solution is less than 20 mus/cm; and (3) placing the washed powder in a vacuum oven, and drying for 7-9 hours at the temperature of 70-90 ℃ to obtain the superfine/nano tantalum-tungsten composite powder.
The invention also aims to provide the superfine/nano tantalum-tungsten composite powder prepared by the preparation method, wherein the grain size is 10-200 nm, the tungsten content (mass percentage) is 2.5-70%, and the balance is tantalum and trace impurities.
The impurities may include one or more of oxygen, carbon, nitrogen, potassium, sodium, calcium, iron, nickel.
Unless otherwise specified, "aqueous ammonia" in the description of the present invention refers to concentrated aqueous ammonia having a concentration of 9.6N.
The term "pure water" as used herein means water treated by reverse osmosis, distillation, EDI (continuous electrodeionization technology) or the like, and contains no impurities or free ions.
The beneficial technical effects of the invention are as follows:
(1) the superfine/nano tantalum-tungsten composite powder prepared by the method has fine grain size, and the grain size is 10-200 nm.
(2) The oxygen content in the superfine/nano tantalum-tungsten composite powder prepared by the method is less than 0.6 wt%, so that the performance of the tantalum-tungsten alloy prepared by the composite powder is improved.
(3) The superfine/nano tantalum-tungsten composite alloy powder prepared by the method has uniform distribution of tantalum and tungsten components, and the component proportion can be conveniently adjusted through the feeding proportion.
(4) The superfine/nano tantalum-tungsten composite powder prepared by the method has high sintering activity. The sintering temperature of the alloy prepared by adopting the tantalum-tungsten composite powder is reduced by 50-100 ℃ compared with that of the alloy prepared by directly mixing common tantalum powder and tungsten powder and prepared by the same components; the tantalum-tungsten composite powder has good sintering characteristics, is suitable for preparing fine-grain tantalum-tungsten alloy processing materials, 3D printing technology and the like, and can meet the requirements of the fields of aerospace, military industry, chemical industry, electronic industry and the like on high-end tantalum-tungsten alloy materials.
(5) The preparation method provided by the invention has the advantages of easily controlled process, large powder yield and easy industrial production.
Detailed Description
The invention provides a preparation method of superfine/nano tantalum-tungsten composite powder, which comprises the following steps of taking a fluorine tantalum acid solution and tungstate as raw materials, and carrying out sol-coprecipitation, hydrogen reduction, alkali metal reduction and magnesium reduction deoxidization, wherein the preparation method comprises the following specific operation steps:
I. sol-co-precipitation
Firstly, adding calculated amount of ammonium paratungstate or ammonium metatungstate powder into a fluorotantalic acid solution, then adding one or more surfactants which are 0.1-3% of the volume of the fluorotantalic acid solution and are selected from PEG-400, PEG-600, PEG-1000 and PEG-2000, and stirring to prepare a sol solution; slowly adding ammonia water to a pH value of 9-12 under ultrasonic oscillation or stirring, standing and aging for 20 minutes to 4 hours, detecting and adjusting the pH value of the solution to the pH value before standing, and performing suction filtration; washing the precipitate with ammonia-blowing hot pure water with ammonia concentration of 0.1-1 mol/L at 40-90 ℃ until the mass percentage of fluorine (F%) is less than 0.5%; placing the washed precipitate in a hot air circulation oven, and drying for 2-10 hours at the temperature of 60-200 ℃ to obtain tantalum-tungsten precursor composite powder; wherein the content of the fluotantalic acid solution is 20-120 g/L in terms of tantalum oxide, and the concentration of HF is 0.3-1.5 mol/L;
reduction of hydrogen
Heating the tantalum-tungsten precursor composite powder obtained in the step I to 600-1000 ℃ in one or more steps in a hydrogen atmosphere, and preserving heat for 0.5-3 hours to obtain tantalum oxide-tungsten composite powder;
reduction of alkali metals
Putting the tantalum oxide-tungsten composite powder obtained in the step II, alkali metal sodium and two or more chlorides selected from calcium chloride, potassium chloride, sodium chloride and magnesium chloride into a reaction device, vacuumizing the reaction device after the materials are put into the reaction device, enabling the vacuum degree to be not more than 26.6Pa, introducing argon as protective gas, heating to 600-1000 ℃, and preserving the heat for 1-6 hours; wherein the mass ratio of sodium to tantalum oxide is 0.2-0.8: 1, and the mass ratio of chloride to tantalum oxide is 1.6: 1 independently; after the reduced product is cooled, washing the solution with normal-temperature pure water until the conductivity of the solution is less than 50 mu s/cm, then washing the solution with 10-60% by volume of one of nitric acid, hydrochloric acid and sulfuric acid until the conductivity of the solution is less than 30 mu s/cm, and finally washing the solution with hot pure water at 40-90 ℃ until the conductivity of the solution is less than 20 mu s/cm; putting the washed powder into a vacuum oven, and drying for 4-12 hours at 60-120 ℃ to obtain tantalum (or tantalum hydride) -tungsten composite powder;
magnesium reduction oxygen removal
Uniformly mixing tantalum (or tantalum hydride) -tungsten composite powder obtained in the alkali metal reduction step and magnesium powder or magnesium sheets, putting the mixture into a reaction bomb, vacuumizing to a vacuum degree of not more than 26.6Pa, introducing argon, heating to 800-1000 ℃, preserving heat, reducing and deoxidizing for 2-5 hours; wherein, when the mass percent of oxygen is 2-4%, the mass of magnesium is 10% of that of tantalum; after the reduced product is cooled, washing the product with 10-60 vol% of one of nitric acid, hydrochloric acid and sulfuric acid until the conductivity of the solution is less than 30 mu s/cm, and then washing the product with normal-temperature pure water or pure water at 40-90 ℃ until the conductivity of the solution is less than 20 mu s/cm; and (3) placing the washed powder in a vacuum oven, and drying for 6-10 hours at the temperature of 60-120 ℃ to obtain the superfine tantalum-tungsten composite powder.
The invention provides a preparation method of superfine tantalum-tungsten composite powder, which comprises the following steps of taking a tantalum fluoride acid solution and tungstate as raw materials, and carrying out sol-co-precipitation, hydrogen reduction, alkali metal reduction and magnesium reduction deoxidization, wherein the preparation method comprises the following specific operation steps:
I. sol-co-precipitation
Firstly, adding calculated amount of ammonium paratungstate or ammonium metatungstate powder into a fluotantalic acid solution, then adding PEG-600 with the volume of 0.5 percent of the fluotantalic acid solution, and stirring to prepare a sol solution; slowly adding 9.6N concentrated ammonia water to a pH value of 9-10 under ultrasonic oscillation or stirring, standing and aging for 0.5 hour, detecting and adjusting the pH value of the solution to the pH value before standing, and performing suction filtration; washing the precipitate with ammonia-blowing hot pure water with ammonia concentration of 0.3mol/L at 70-80 ℃ until the fluorine mass percentage content (F%) is less than 0.5%; placing the washed precipitate in a hot air circulation oven, and drying for 4 hours at 110-120 ℃ to obtain tantalum-tungsten precursor composite powder; wherein the content of the fluotantalic acid solution is 20-120 g/L in terms of tantalum oxide, and the concentration of HF is 0.3-1.5 mol/L;
reduction of hydrogen
Heating the tantalum-tungsten precursor composite powder obtained in the step I to 850-900 ℃ in a hydrogen atmosphere, and preserving heat for 1 hour to obtain tantalum oxide-tungsten composite powder;
reduction of alkali metals
Putting the tantalum oxide-tungsten composite powder obtained in the step II, alkali metal sodium, calcium chloride, potassium chloride and sodium chloride into a reaction device, vacuumizing the reaction device after the materials are put into the reaction device, enabling the vacuum degree to be not more than 26.6Pa, introducing argon gas serving as protective gas, heating to 920 ℃, and keeping the temperature for 4 hours; wherein the mass ratio of sodium to tantalum oxide is 0.6: 1, and the mass ratio of chloride to tantalum oxide is 1.6: 1; after the reduced product is cooled, washing the product with normal-temperature pure water until the conductivity of the solution is less than 50 mu s/cm, washing the product with nitric acid with the volume percentage of 40% until the conductivity of the solution is less than 30 mu s/cm, and finally washing the product with hot pure water at the temperature of 70-80 ℃ until the conductivity of the solution is less than 20 mu s/cm; putting the washed powder into a vacuum oven, and drying for 8-10 hours at 80-100 ℃ to obtain tantalum (or tantalum hydride) -tungsten composite powder;
magnesium reduction oxygen removal
Reducing and deoxidizing the tantalum (or tantalum hydride) -tungsten composite powder obtained in the alkali metal reduction step for 2-3 hours at 900-950 ℃ by adopting a magnesium sheet; wherein the mass of the magnesium is 8-12% of that of the tantalum; after the reduced product is cooled, washing the product with nitric acid with the volume percentage of 40% until the conductivity of the solution is less than 30 mus/cm, and then washing the product with pure water at the temperature of 70-80 ℃ until the conductivity of the solution is less than 20 mus/cm; and (3) placing the washed powder in a vacuum oven, and drying for 7-9 hours at the temperature of 70-90 ℃ to obtain the superfine/nano tantalum-tungsten composite powder.
The present invention will be described in detail below with reference to specific examples. It will be understood by those skilled in the art that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention in any way.
The experimental procedures in the following examples are conventional unless otherwise specified. The various starting materials used in the following examples are all commercially available products unless otherwise specified.
Example 1Preparation of Ta-10 wt% W superfine/nano composite powder
Step 1, sol-co-precipitation
(1) Weighing 406g of Ammonium Paratungstate (APT), dissolving into a container containing 30L of fluotantalic acid solution, dropwise adding 300ml of surfactant polyethylene glycol (PEG-600), and fully stirring for 30 minutes to obtain sol solution; wherein the concentration of the fluotantalic acid solution is 100g/L and the HF concentration is 1.2mol/L in terms of tantalum oxide.
(2) Slowly adding concentrated ammonia water (the concentration is 9.6N) into the sol solution, continuously stirring while adding until the pH value of the solution is 9-10, stopping dropwise adding the concentrated ammonia water, standing for 30 minutes, detecting the change of the pH value, and ensuring that the pH value of the solution is 9-10.
(3) Filtering the precipitate by using a suction filtration device, and fully washing and filtering the precipitate by using drum ammonia hot pure water with the concentration of 0.3mol/L at 75 ℃ in sequence until the fluorine content in the precipitate is less than 0.5 percent. Then placing the powder after precipitation and filtration in a hot air circulation oven for drying for 4 hours at 120 ℃, and sieving by a 100-mesh sieve to obtain the powder prepared by Ta (OH)5、(NH4)10(H2W12O42)·4H2And precursor composite powder consisting of O phase.
Step 2, hydrogen reduction
The precursor composite powder obtained in the step 1 is subjected to one-step heating to 900 ℃ in a fourteen-tube hydrogen reduction furnace, and is subjected to reduction and heat preservation for 1 hour to obtain tantalum oxide-tungsten (chemical composition (Ta, O) and W) composite powder;
step 3, alkali metal reduction
(1) Transferring the tantalum oxide-tungsten composite powder obtained in the step 2 into a reaction bomb (special stirring sodium reduction equipment), adding alkali metal sodium, calcium chloride, potassium chloride and sodium chloride, wherein 1700 g of sodium, 5020 g of calcium chloride, 5020 g of potassium chloride and 5020 g of sodium chloride are added, vacuumizing the reaction bomb after the feeding is finished, wherein the vacuum degree is not more than 26.6Pa, introducing argon as a protective gas, raising the temperature to 920 ℃, reducing and preserving the temperature for 4 hours.
(2) And after the sodium reducing material is cooled, stripping the material from the reaction bomb and crushing the material, washing soluble salt and excessive alkali metal by using pure water until the conductivity of the solution is less than 50 mu s/cm, washing the solution for 2 hours by using nitric acid with the concentration of 40 percent, washing the solution until the conductivity of the solution is less than 30 mu s/cm at the acid washing end point, then washing the solution by using pure water with the temperature of 80 ℃ until the conductivity of the solution is less than 20 mu s/cm, putting the obtained powder in a vacuum oven, drying the powder at the temperature of 80 ℃ for 8 hours, and obtaining the tantalum-tungsten composite powder.
And detecting the performance of the powder, wherein the grain size is 10-200 nm, and the contents of related elements are respectively as follows: w: 9.6%, C: 0.02%, N: 0.065%, O: 2.8%, K: 0.002%, Na: 0.0035%, Ca: 0.002%, Fe 0.01%, Ni 0.0018%, and the balance tantalum.
Step 4, magnesium reduction deoxidation
Adding 110 g of magnesium sheets into the tantalum-tungsten composite powder obtained in the step 3, uniformly mixing, putting into a reaction bomb, vacuumizing to ensure that the vacuum degree is not more than 26.6Pa, introducing argon, heating to 940 ℃, keeping the temperature for 2 hours, cooling to room temperature, discharging, washing with 40% nitric acid for 2 hours, washing with acid until the solution conductivity is less than 30 mu s/cm, washing with 75 ℃ hot pure water until the solution conductivity is less than 20 mu s/cm, drying, and sieving with a 100-mesh sieve to obtain the ultrafine (nano) tantalum-tungsten composite powder with Ta-10 wt%.
Detecting the performance of the composite alloy powder, wherein the grain size is 10-220 nm, and the contents of related elements are respectively as follows: w: 9.5%, C: 0.01%, N: 0.035%, O: 0.28%, K: 0.001%, Na: 0.0015%, Ca: 0.001%, Fe 0.005%, Ni 0.0016%, and the balance tantalum. The composite alloy powder had an average particle size of 2 μm. The powder yield was 86% throughout the process of this example.
EXAMPLE 2Preparation of Ta-20 wt% W superfine/nano composite powder
Step 1, sol coprecipitation
(1) 916g of Ammonium Paratungstate (APT) is weighed and dissolved in a plastic barrel containing 30L of fluotantalic acid solution, 300ml of surfactant polyethylene glycol PEG-1200 is dripped, and the mixture is fully stirred for 30 minutes. Obtaining a sol solution; wherein the concentration of the fluotantalic acid solution is 100g/L and the HF concentration is 1.2mol/L in terms of tantalum oxide.
(2) Slowly adding concentrated ammonia water (the concentration is 9.6N) into the sol solution, continuously stirring while adding until the pH value of the solution is slightly larger than 9, stopping dropwise adding the concentrated ammonia water, standing for 30 minutes, detecting the change of the pH value, and ensuring that the pH value of the solution is 9.
(3) And (3) filtering the precipitate by using a suction filtration system, and fully washing and filtering the precipitated starch material by using drum ammonia hot pure water with ammonia concentration of 0.3mol/L at 40-50 ℃ until the fluorine content in the precipitate is less than 0.5%. Then placing the powder after precipitation and filtration in a hot air circulation oven for drying for 2 hours at 200 ℃, and sieving with a 100-mesh sieve to obtain the tantalum oxide-tungsten precursor composite powder (chemical composition is Ta (OH))5+(NH4)10(H2W12O42)·4H2O)。
Step 2, hydrogen reduction
Heating the tantalum oxide-tungsten precursor composite powder obtained in the step 1 to 900 ℃ in one step in a fourteen-tube hydrogen reduction furnace, reducing and preserving heat for 1 hour to obtain tantalum oxide-tungsten composite powder;
step 3, alkali metal reduction
(1) Transferring the tantalum oxide-tungsten composite powder obtained in the step 2 into a reaction bomb (special stirring sodium reduction equipment), adding alkali metal sodium, calcium chloride, potassium chloride and sodium chloride, wherein 1800 g of sodium, 5500 g of calcium chloride, 5500 g of potassium chloride and 5500 g of sodium chloride, vacuumizing to a vacuum degree of not more than 26.6Pa after feeding is finished, introducing argon as protective gas, heating to 920 ℃, and carrying out heat preservation reaction for 4 hours.
(2) And when the sodium reducing material is cooled, stripping the material from the reaction bomb and crushing the material, washing soluble salt and excessive alkali metal by using pure water until the conductivity of the solution is less than 50 mu s/cm, washing the solution for 2 hours by using nitric acid with the concentration of 40 percent, washing the solution until the conductivity of the solution is less than 30 mu s/cm at the acid washing end point, then washing the solution by using pure water with the temperature of 50-60 ℃ until the conductivity of the solution is less than 20 mu s/cm, placing the obtained powder in a vacuum oven, drying the powder at the temperature of 80 ℃ for 9 hours, and obtaining the tantalum-tungsten composite powder. And detecting the performance of the powder, wherein the grain size is 10-210 nm, and the contents of related elements are respectively as follows: w: 18.2%, C: 0.05%, N: 0.08%, O: 3.1%, K: 0.002%, Na: 0.0015%, Ca: 0.0025 percent, 0.01 percent of Fe, 0.005 percent of Ni and the balance of tantalum.
Step 4, magnesium reduction deoxidation
Adding 120g of magnesium sheets into the tantalum-tungsten composite powder obtained in the step 3, uniformly mixing, putting into a reaction bomb, vacuumizing to ensure that the vacuum degree is not more than 26.6Pa, introducing argon, heating to 940 ℃, keeping the temperature for 2 hours, cooling to room temperature, discharging, washing with 40% nitric acid for 2 hours, washing with acid until the solution conductivity is less than 30 mu s/cm, washing with 75 ℃ hot pure water until the solution conductivity is less than 20 mu s/cm, drying, and sieving with a 100-mesh sieve to obtain Ta-20 wt% W superfine/nano tantalum-tungsten composite alloy powder.
And detecting the performance of the powder, wherein the grain size is 20-200 nm, and the contents of related elements are respectively as follows: w: 19%, C: 0.02%, N: 0.006%, O: 0.35%, K: 0.002%, Na: 0.002%, Ca: 0.002%, Fe: 0.005%, Ni: 0.008% and the balance tantalum. The average particle size of the powder is 2-3 μm.
The powder yield in the whole process of the embodiment is 85%.
EXAMPLE 3Preparation of Ta-30 wt% W superfine/nano composite powder
Step 1, sol-co-precipitation
(1) 1570g of Ammonium Paratungstate (APT) powder was weighed and dissolved in a container containing 30L of a fluorotantalic acid solution, and 300ml of a surfactant polyethylene glycol PEG-400 was added dropwise thereto, followed by sufficient stirring for 30 minutes. Wherein the concentration of the fluotantalic acid solution is 100g/L and the HF concentration is 1.2mol/L in terms of tantalum oxide. .
(2) Slowly adding concentrated ammonia water (the concentration is 9.6N) into the sol solution, continuously stirring while adding until the pH value of the solution is 10-11, stopping dropwise adding the concentrated ammonia water, standing for 30 minutes, detecting and adjusting the pH value, and ensuring that the pH value of the solution is 10-11.
(3) Use ofAnd (3) filtering the precipitate by using a suction filtration system, and fully washing and filtering the precipitate by using drum ammonia hot pure water with the ammonia concentration of 0.3mol/L at 50-60 ℃ until the fluorine content in the precipitate is less than 0.5%. Then the filter cake is placed in a hot air circulation oven, dried for 4 hours at 120 ℃, and sieved by a 100-mesh sieve to obtain precursor composite powder (chemical composition Ta (OH))5+(NH4)10(H2W12O42)·4H2O)。
Step 2, hydrogen reduction
Heating the precursor composite powder to 900 ℃ in a fourteen-tube hydrogen reduction furnace in one step, reducing and preserving heat for 1 hour to obtain tantalum oxide-tungsten composite powder;
step 3, alkali metal reduction
(1) Transferring the tantalum oxide-tungsten composite powder obtained in the step 2 into a reaction bomb (special stirring sodium reduction equipment), adding alkali metal sodium, calcium chloride, potassium chloride and sodium chloride, wherein the sodium 1900 g, the calcium chloride 6000 g, the potassium chloride 6000 g and the sodium chloride 6000 g are added, vacuumizing the system after feeding, wherein the vacuum degree is not more than 26.6Pa, and introducing argon as protective gas; the temperature is raised to 900 ℃ for reduction and heat preservation for 2 hours.
(2) And when the sodium reducing material is cooled, stripping the material from the reaction bomb and crushing the material, washing soluble salt and excessive alkali metal by using pure water until the conductivity of the solution is less than 50 mu s/cm, washing the solution by using sulfuric acid with the volume concentration of 30% until the conductivity of the solution is less than 30 mu s/cm, then washing the solution by using pure water with the temperature of 80-90 ℃ until the conductivity of the solution is less than 20 mu s/cm, placing the obtained powder in a vacuum oven, drying the powder at the temperature of 80 ℃, and drying the powder for 9 hours to obtain the tantalum-tungsten composite powder. And detecting the performance of the powder, wherein the grain size is 10-200 nm, and the contents of related elements are respectively as follows: w: 28%, C: 0.05%, N: 0.18%, O: 3.8%, K: 0.005%, Na: 0.0035%, Ca: 0.002%, Fe 0.01%, Ni 0.004%, and the balance tantalum.
Step 4, magnesium reduction deoxidation
Adding 120g of magnesium sheets into the tantalum-tungsten composite powder obtained in the step (3), uniformly mixing, putting into a reaction bomb, vacuumizing to a vacuum degree of not more than 26.6Pa, introducing argon, heating to 940 ℃, keeping the temperature for 2 hours, cooling to room temperature, discharging, washing with sulfuric acid with a volume concentration of 30% until the solution conductivity is less than 30 mus/cm, washing with hot pure water with a temperature of 75 ℃ until the solution conductivity is less than 20 mus/cm, drying, and sieving with a 100-mesh sieve to obtain ultrafine (nano) tantalum-tungsten composite alloy powder with Ta-30 wt% W.
Detecting the performance of the composite alloy powder, wherein the grain size is 20-220 nm, and the contents of related elements are respectively as follows: w: 27.5%, C: 0.03%, N: 0.05%, O: 0.45%, K: 0.003%, Na: 0.001%, Ca: 0.002%, Fe 0.005%, Ni 0.002%, and the balance tantalum. The average particle size of the composite powder is 2-4 μm.
The powder yield for the whole process of this example was 84.5%.
Example 4Preparation of Ta-40 wt% W superfine/nano composite powder
Step 1, sol-co-precipitation
(1) 2440g of ammonium paratungstate powder (APT) was weighed and dissolved in a container containing 30L of a fluorotantalic acid solution, and 300ml of a surfactant polyethylene glycol PEG-600 was added dropwise thereto, followed by thorough stirring for 30 minutes. The concentration of the fluotantalic acid solution is 100g/L and the HF concentration is 1.2mol/L in terms of tantalum oxide.
(2) Slowly adding concentrated ammonia water (with the concentration of 9.6N) into the sol solution under ultrasonic oscillation until the pH value of the solution is 9-10, stopping dropwise adding the concentrated ammonia water, standing for 30 minutes, detecting the pH value and adjusting the pH value to be 9-10.
(3) And (3) filtering the precipitate by using a suction filtration system, and fully washing and filtering the precipitate by using drum ammonia hot pure aqueous ammonia with the ammonia concentration of 0.3mol/L at 75 ℃ and pure water until the fluorine content in the precipitate is less than 0.5 percent. Then the filter cake is placed in a hot air circulation oven, dried for 4 hours at 120 ℃, and sieved by a 100-mesh sieve to obtain precursor composite powder (chemical composition Ta (OH))5+ (NH4)10(H2W12O42)·4H2O)。
Step 2, hydrogen reduction
And (3) heating the precursor composite powder obtained in the step (1) to 900 ℃ in one step in a fourteen-tube hydrogen reduction furnace, reducing and preserving heat for 1 hour to obtain tantalum oxide-tungsten composite powder.
Step 3, alkali metal reduction
(1) Transferring the tantalum oxide-tungsten composite powder obtained in the step 2 into a reaction bomb (special stirring sodium reduction equipment), adding alkali metal sodium, calcium chloride, potassium chloride and sodium chloride, wherein 2000 g of sodium, 7000 g of calcium chloride, 7000 g of potassium chloride and 7000 g of sodium chloride are added, vacuumizing the system after feeding is finished, the vacuum degree is not more than 26.6Pa, introducing argon as protective gas, heating to 920 ℃, reducing and preserving heat for 4 hours.
(2) And when the sodium reducing material is cooled, stripping the material from the reaction bomb and crushing the material, washing soluble salt and excessive alkali metal by using pure water until the conductivity of the solution is less than 50 mu s/cm, washing the solution for 2 hours by using nitric acid with the concentration of 40 percent, washing the solution until the conductivity of the solution is less than 30 mu s/cm at the acid washing end point, washing the solution by using hot pure water at the temperature of 75 ℃ until the conductivity of the solution is less than 20 mu s/cm, putting the obtained powder in a vacuum oven, drying the powder at the temperature of 80 ℃ for 8 hours, and obtaining the tantalum-tungsten composite powder. And detecting the performance of the powder, wherein the grain size is 20-230 nm, and the contents of related elements are respectively as follows: w: 37.5%, C: 0.073%, N: 0.15%, O: 4.1%, K: 0.002%, Na: 0.025%, Ca: 0.005%, Fe: 0.01%, Ni: 0.005% and the balance tantalum.
Step 4, magnesium reduction deoxidation
Adding 130 magnesium sheets into the tantalum-tungsten composite powder obtained in the step (3), uniformly mixing, putting into a reaction bomb, vacuumizing a system, wherein the vacuum degree is not more than 26.6Pa, introducing argon, heating to 940 ℃, keeping the temperature for 2 hours, cooling to room temperature, discharging, washing with nitric acid with the concentration of 40% for 2 hours, washing with acid until the solution conductivity is less than 30 mu s/cm, washing with hot pure water with the temperature of 75 ℃ until the solution conductivity is less than 20 mu s/cm, drying at the temperature of 85 ℃ for 9 hours, and sieving with a 100-mesh sieve to obtain the ultrafine (nano) tantalum-tungsten composite alloy powder with the weight percent of Ta-40W.
Detecting the performance of the composite alloy powder, wherein the grain size is 20-220 nm, and the contents of related elements are respectively as follows: w: 37%, C: 0.02%, N: 0.065%, O: 0.55%, K: 0.003%, Na: 0.005%, Ca: 0.003%, Fe 0.0045%, Ni 0.003%, and the balance tantalum. The average particle size of the composite alloy powder is 2-4 μm.
The powder yield was 85% throughout the process of this example.
The above description of the specific embodiments of the present invention is not intended to limit the present invention, and those skilled in the art may make various changes and modifications according to the present invention without departing from the spirit of the present invention, which is defined by the scope of the appended claims.
Claims (31)
1. A method for preparing superfine/nano tantalum-tungsten composite powder takes a fluorine-tantalum acid solution and tungstate as raw materials, and comprises sol-coprecipitation, hydrogen reduction, alkali metal reduction and magnesium reduction deoxidization; the specific operation of the sol-coprecipitation step is as follows:
firstly, adding calculated amount of ammonium paratungstate or ammonium metatungstate powder into a fluotantalic acid solution, then adding PEG-600 with the volume of 0.5 percent of the fluotantalic acid solution, and stirring to prepare a sol solution; slowly adding ammonia water serving as a precipitator to the pH = 9-10 under ultrasonic oscillation or stirring, standing and aging for 0.5 hour, detecting and adjusting the pH value of the solution to the pH value before standing, and performing suction filtration; washing the precipitate with ammonia-blowing hot pure water with ammonia concentration of 0.3mol/L at 70-80 ℃ until the mass percentage of fluorine is less than 0.5%; placing the washed precipitate in a hot air circulation oven, and drying for 4 hours at 110-130 ℃ to obtain tantalum-tungsten precursor composite powder; wherein the content of the fluotantalic acid solution is 20-120 g/L in terms of tantalum oxide, and the HF concentration is 0.3-1.5 mol/L.
2. The preparation method according to claim 1, wherein in the hydrogen reduction step, the tantalum-tungsten precursor composite powder obtained in the sol-coprecipitation step is heated to 600-1000 ℃ in one or more steps in a hydrogen atmosphere, and the temperature is maintained for 0.5-3 hours to obtain the tantalum oxide-tungsten composite powder.
3. The preparation method according to claim 2, wherein in the hydrogen reduction step, the tantalum-tungsten precursor composite powder is heated to 850-900 ℃ in one or more steps in a hydrogen atmosphere, and is subjected to heat preservation for 1 hour to obtain the tantalum oxide-tungsten composite powder.
4. The preparation method according to claim 3, wherein in the hydrogen reduction step, the tantalum-tungsten precursor composite powder is subjected to one-step temperature rise to 850-900 ℃ in a hydrogen atmosphere, and is subjected to heat preservation for 1 hour to obtain the tantalum oxide-tungsten composite powder.
5. The method according to claim 1, wherein in the alkali metal reduction step, the tantalum oxide-tungsten composite powder obtained in the hydrogen reduction step is subjected to co-reduction with an alkali metal sodium and two or more chlorides selected from calcium chloride, potassium chloride, sodium chloride and magnesium chloride at 600 to 1000 ℃, and the heat preservation time is 1 to 6 hours; then pure water washing, acid washing and hot pure water washing are carried out, and tantalum or tantalum hydride-tungsten composite powder is obtained after drying; wherein the mass ratio of sodium to tantalum oxide is 0.2-0.8: 1, and the mass ratio of chloride to tantalum oxide is 1.2-2.5: 1.
6. The method according to claim 5, wherein the reduction temperature in the alkali metal reduction step is 900 to 950 ℃.
7. The production method according to claim 6, wherein in the alkali metal reduction step, the reduction temperature is 920 ℃.
8. The method according to claim 5, wherein the alkali metal reduction step is carried out for 4 hours.
9. The method according to claim 5, wherein the mass ratio of sodium to tantalum oxide in the alkali metal reduction step is 0.6: 1.
10. The production method according to claim 5, wherein in the alkali metal reduction step, the chloride is selected from two or more of calcium chloride, potassium chloride and sodium chloride.
11. The method according to claim 10, wherein the calcium chloride, potassium chloride and sodium chloride are used in a mass ratio of 1.6: 1 to the tantalum oxide.
12. The preparation method according to claim 5, wherein the pure water washing is normal-temperature pure water washing, and the washing end point is that the solution conductivity is less than 50 μ s/cm; the pickling detergent is selected from one or more of nitric acid, hydrochloric acid and sulfuric acid, the volume percentage concentration of the acid is 10-60%, and the pickling end point is that the conductivity of the solution is less than 30 mu s/cm; and the hot pure water washing is carried out by washing with hot pure water at the temperature of 40-90 ℃ until the conductivity of the solution is less than 20 mu s/cm.
13. The method of claim 12, wherein the acid wash detergent is nitric acid having a concentration of 40% by volume.
14. The method according to claim 12, wherein the temperature of the hot pure water is 70 to 80 ℃.
15. The preparation method according to claim 5, wherein in the alkali metal reduction step, the drying device is a vacuum oven, the drying temperature is 60-120 ℃, and the drying time is 4-12 hours.
16. The method according to claim 15, wherein the drying temperature is 80 to 100 ℃ and the drying time is 8 to 10 hours.
17. The method according to claim 1, wherein the alkali metal reduction step is carried out by:
reducing the tantalum oxide-tungsten composite powder obtained in the hydrogen reduction step by using alkali metal sodium, calcium chloride, potassium chloride and sodium chloride at 900-950 ℃, and preserving the heat for 4 hours; wherein the mass ratio of sodium to tantalum oxide is 0.6: 1, and the mass ratio of chloride to tantalum oxide is 1.6: 1; after the reduced product is cooled, washing the solution with normal-temperature pure water until the conductivity of the solution is less than 50 mu s/cm, then washing the solution with one of nitric acid, hydrochloric acid and sulfuric acid with the volume percentage of 10-60% until the conductivity of the solution is less than 30 mu s/cm, and finally washing the solution with hot pure water at the temperature of 40-90 ℃ until the conductivity of the solution is less than 20 mu s/cm; and (3) placing the washed powder in a vacuum oven, and drying for 4-12 hours at the temperature of 60-120 ℃ to obtain the tantalum or tantalum hydride-tungsten composite powder.
18. The method according to claim 17, wherein the alkali metal reduction step is carried out by:
reducing the tantalum oxide-tungsten composite powder obtained in the hydrogen reduction step by using alkali metal sodium, calcium chloride, potassium chloride and sodium chloride at 920 ℃, and preserving the temperature for 4 hours; wherein the mass ratio of sodium to tantalum oxide is 0.6: 1, and the mass ratio of chloride to tantalum oxide is 1.6: 1; after the reduced product is cooled, washing the product with normal-temperature pure water until the conductivity of the solution is less than 50 mu s/cm, washing the product with nitric acid with the volume percentage of 40% until the conductivity of the solution is less than 30 mu s/cm, and finally washing the product with hot pure water at the temperature of 70-80 ℃ until the conductivity of the solution is less than 20 mu s/cm; and (3) putting the washed powder into a vacuum oven, and drying for 8-10 hours at the temperature of 80-100 ℃ to obtain the tantalum or tantalum hydride-tungsten composite powder.
19. The preparation method of claim 1, wherein in the magnesium reduction and oxygen removal step, the tantalum or tantalum hydride-tungsten composite powder obtained in the alkali metal reduction step is subjected to magnesium reduction and oxygen removal for 2-5 hours at 800-1000 ℃; and (3) carrying out acid washing, water washing and drying to obtain the superfine tantalum-tungsten composite powder.
20. The preparation method according to claim 19, wherein in the step of deoxidizing by reducing magnesium, deoxidizing and deoxidizing by reducing magnesium are performed for 2 to 3 hours at 900 to 950 ℃.
21. The method of claim 19 or 20, wherein magnesium powder or magnesium flakes are used.
22. The production method according to claim 19 or 20, wherein the mass of magnesium is 8 to 12% of the mass of tantalum.
23. The preparation method of claim 19, wherein the pickling detergent is one or more selected from nitric acid, hydrochloric acid and sulfuric acid, and the acid concentration is 10-60% by volume; the acid washing end point is that the conductivity of the solution is less than 30 mu s/cm.
24. The method of claim 23, wherein the acid wash detergent is nitric acid having a concentration of 40% by volume.
25. The method according to claim 19, wherein the washing agent for washing with water is selected from pure water or hot pure water at 40 to 90 ℃, and the washing with water is terminated until the solution conductivity is less than 20 μ s/cm.
26. The method according to claim 25, wherein the washing agent for washing with water is hot pure water at 70 to 80 ℃.
27. The preparation method of claim 19, wherein the drying device is a vacuum oven, the drying temperature is 60 ℃ to 120 ℃, and the drying time is 6 hours to 10 hours.
28. The method according to claim 27, wherein the drying temperature is 75 to 90 ℃ and the drying time is 7 to 9 hours.
29. The preparation method according to claim 1, wherein the magnesium reduction oxygen removal step is specifically performed by:
deoxidizing the tantalum or tantalum hydride-tungsten composite powder obtained in the alkali metal reduction step by adopting magnesium powder or magnesium sheets for 2-5 hours at 800-1000 ℃; wherein the mass of the magnesium is 8-12% of that of the tantalum; after the reduced product is cooled, washing the product with one of nitric acid, hydrochloric acid and sulfuric acid with the volume percentage of 10-60% until the conductivity of the solution is less than 30 mus/cm, and then washing the product with pure water at the temperature of 40-90 ℃ until the conductivity of the solution is less than 20 mus/cm; and (3) placing the washed powder in a vacuum oven, and drying for 6-10 hours at the temperature of 60-120 ℃ to obtain the superfine tantalum-tungsten composite powder.
30. The preparation method according to claim 29, wherein the magnesium reduction oxygen removal step is specifically performed by:
reducing and deoxidizing the tantalum or tantalum hydride-tungsten composite powder obtained in the alkali metal reduction step for 2-3 hours at 900-950 ℃ by using a magnesium sheet; wherein, when the mass percent of oxygen is 2-4%, the mass of magnesium is 10% of that of tantalum; after the reduced product is cooled, washing the product with nitric acid with the volume percentage of 40% until the conductivity of the solution is less than 30 mus/cm, and then washing the product with pure water at the temperature of 70-80 ℃ until the conductivity of the solution is less than 20 mus/cm; and (3) placing the washed powder in a vacuum oven, and drying for 7-9 hours at the temperature of 70-90 ℃ to obtain the superfine tantalum-tungsten composite powder.
31. The superfine tantalum-tungsten composite powder is prepared by the preparation method of any one of claims 1 to 30, the grain size is 10-200 nm, the mass percent of tungsten is 2.5-70%, and the balance is tantalum and trace impurities.
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| CN103600086A (en) * | 2013-12-03 | 2014-02-26 | 宁夏东方钽业股份有限公司 | Powder metallurgy tantalum powder and/or niobium powder and preparing method thereof |
| CN104722767A (en) * | 2015-04-16 | 2015-06-24 | 柳州豪祥特科技有限公司 | Tungsten powder preparation method |
| CN104722770A (en) * | 2015-04-16 | 2015-06-24 | 柳州豪祥特科技有限公司 | Method for preparing tungsten-molybdenum powder |
| CN104942303A (en) * | 2015-07-01 | 2015-09-30 | 崇义章源钨业股份有限公司 | Method for preparing tungsten powder |
| CN105238983A (en) * | 2015-09-29 | 2016-01-13 | 河南科技大学 | Rare-earth oxide doped tungsten-copper alloy composite material and preparation method thereof |
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