CN114346249A - Preparation method of high-purity superfine spherical tantalum powder - Google Patents
Preparation method of high-purity superfine spherical tantalum powder Download PDFInfo
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- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 title claims abstract description 135
- 238000002360 preparation method Methods 0.000 title description 4
- 239000011777 magnesium Substances 0.000 claims abstract description 95
- 229910052749 magnesium Inorganic materials 0.000 claims abstract description 95
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims abstract description 92
- BPUBBGLMJRNUCC-UHFFFAOYSA-N oxygen(2-);tantalum(5+) Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Ta+5].[Ta+5] BPUBBGLMJRNUCC-UHFFFAOYSA-N 0.000 claims abstract description 66
- PBCFLUZVCVVTBY-UHFFFAOYSA-N tantalum pentoxide Inorganic materials O=[Ta](=O)O[Ta](=O)=O PBCFLUZVCVVTBY-UHFFFAOYSA-N 0.000 claims abstract description 66
- -1 magnesium nitride Chemical class 0.000 claims abstract description 64
- 229910052751 metal Inorganic materials 0.000 claims abstract description 51
- 239000002184 metal Substances 0.000 claims abstract description 51
- 239000002253 acid Substances 0.000 claims abstract description 24
- 238000000034 method Methods 0.000 claims abstract description 24
- 238000005245 sintering Methods 0.000 claims abstract description 18
- 239000000395 magnesium oxide Substances 0.000 claims abstract description 14
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 claims abstract description 14
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 13
- 238000004519 manufacturing process Methods 0.000 claims abstract description 8
- 238000010521 absorption reaction Methods 0.000 claims abstract description 5
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 5
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 claims abstract description 4
- 239000000463 material Substances 0.000 claims description 82
- 238000001816 cooling Methods 0.000 claims description 32
- 239000002245 particle Substances 0.000 claims description 28
- 238000001035 drying Methods 0.000 claims description 14
- 239000000203 mixture Substances 0.000 claims description 12
- 239000011261 inert gas Substances 0.000 claims description 10
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 9
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 8
- 229910017604 nitric acid Inorganic materials 0.000 claims description 8
- 230000002195 synergetic effect Effects 0.000 claims description 5
- 238000005406 washing Methods 0.000 claims description 4
- 238000000498 ball milling Methods 0.000 claims 7
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims 2
- 239000004615 ingredient Substances 0.000 claims 2
- 230000003068 static effect Effects 0.000 claims 1
- 239000011164 primary particle Substances 0.000 abstract 1
- 239000000843 powder Substances 0.000 description 72
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 64
- 238000010438 heat treatment Methods 0.000 description 56
- 229910052715 tantalum Inorganic materials 0.000 description 49
- 238000006243 chemical reaction Methods 0.000 description 33
- 229910052786 argon Inorganic materials 0.000 description 32
- 238000000227 grinding Methods 0.000 description 27
- 238000011049 filling Methods 0.000 description 25
- 229920002635 polyurethane Polymers 0.000 description 20
- 239000004814 polyurethane Substances 0.000 description 20
- 238000006722 reduction reaction Methods 0.000 description 19
- 238000007789 sealing Methods 0.000 description 19
- 238000001514 detection method Methods 0.000 description 14
- 238000009837 dry grinding Methods 0.000 description 12
- 239000010935 stainless steel Substances 0.000 description 12
- 229910001220 stainless steel Inorganic materials 0.000 description 12
- 238000002791 soaking Methods 0.000 description 10
- 238000003756 stirring Methods 0.000 description 10
- 239000012498 ultrapure water Substances 0.000 description 10
- 238000002156 mixing Methods 0.000 description 7
- 239000003990 capacitor Substances 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 6
- 238000011068 loading method Methods 0.000 description 6
- 239000007789 gas Substances 0.000 description 5
- 230000036632 reaction speed Effects 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 4
- 239000007787 solid Substances 0.000 description 3
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 2
- 229910000905 alloy phase Inorganic materials 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 238000004891 communication Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 239000004482 other powder Substances 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 229910052700 potassium Inorganic materials 0.000 description 2
- 239000011591 potassium Substances 0.000 description 2
- 238000005086 pumping Methods 0.000 description 2
- 239000000376 reactant Substances 0.000 description 2
- 238000001878 scanning electron micrograph Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 229910001936 tantalum oxide Inorganic materials 0.000 description 2
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- 229910020056 Mg3N2 Inorganic materials 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 238000011031 large-scale manufacturing process Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 238000007873 sieving Methods 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
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Abstract
A method for manufacturing high-purity superfine spherical tantalum powder comprises the following steps: the high-purity ultrafine magnesium nitride and metal magnesium powder are used as binary cooperative reducing agents, the high-purity ultrafine metal tantalum powder is used as a heat absorption medium, a heat conduction medium and a position resisting agent in an auxiliary mode, sintering is carried out in two steps or three steps, preferably, rotary kiln dynamic sintering is adopted to completely reduce the high-purity ultrafine tantalum pentoxide, then, the generated magnesium oxide and the surplus unreacted metal magnesium/magnesium nitride are dissolved by dilute acid solution, and the high-purity ultrafine metal tantalum powder with the primary particle size of 100-.
Description
Technical Field
The invention belongs to the field of metal powder manufacturing, and particularly relates to a manufacturing method of high-purity superfine spherical tantalum powder.
Background
The metal tantalum is a valve metal which can form a dense oxide film on the surface and has one-way conductivity. The tantalum capacitor made of the metal tantalum powder has the advantages of stable chemical property, high resistivity, large dielectric constant, small leakage current, wide working temperature range, high reliability, strong shock resistance and self-healing capability, long service life and the like. Because of its many advantages, tantalum capacitors are widely used in electronic devices such as aviation, aerospace, communications, computers, mobile phones, etc. The tantalum capacitor has the advantages of high capacity, small volume, strong self-healing capability, high reliability and the like, and is widely applied to the high-end technical fields of communication, computers, automotive electronics, radars, missiles, aviation, aerospace, automatic control devices, electronic measuring instruments and the like. The application of tantalum powder in the capacitor accounts for about 60-70% of the total consumption of tantalum in the world. Particularly, in recent years, with the rapid development of the computer and electronics industries, demand for tantalum has been steadily increasing.
The large-scale production of tantalum powder has been over 70 years, and the main methods for preparing tantalum powder traditionally include vacuum carbothermic reduction of tantalum pentoxide and reduction of potassium fluotantalate by metallic sodium. The purity of the tantalum powder prepared by the former is low, and the tantalum powder can only be applied to the preparation of metallurgical-grade tantalum powder. The latter also has some drawbacks: the average particle size of tantalum is larger due to strong heat release and high temperature of the reduction reaction, the tantalum powder with high specific capacity is difficult to prepare, and a large amount of harmful fluoride is generated in the reaction, so that the environment is greatly influenced.
In order to increase the CV value (electrostatic capacity voltage/weight, uFV/g) of the metal tantalum powder for tantalum capacitors, the intermediate raw material for producing tantalum powder was gradually changed from potassium fluotantalate to tantalum pentoxide. Reaction of magnesiothermic reduction of tantalum pentoxide:
5Mg+Ta2O5Δ H-1022.573 kJ at 800 deg.C of 5MgO +2Ta
The reaction is strongly exothermic. Δ G ═ 850.310kJ, the reaction rate was very high, and it was difficult to obtain ultrafine tantalum powder of 5um or less. And because the reaction is strong in heat release and high in reaction speed, the generated agglomerated tantalum particles contain incompletely reduced tantalum oxide, and the oxygen content of the product is high. The reduction of tantalum pentoxide by magnesium metal is theoretically possible, but the actual production cannot obtain high-purity ultrafine tantalum metal powder.
The Shitach company in Germany developed a process for reducing tantalum pentoxide with gaseous magnesium on the basis of the technology for reducing tantalum pentoxide with solid magnesium. Because the reaction of the gaseous magnesium and the tantalum pentoxide is still strong in heat release, the reaction speed and the reaction heat release are controlled by controlling the magnesium vapor entering the reaction kettle, and the production efficiency is low. The method also has the following two problems in the actual industrial production: firstly, a lot of magnesium and products are adhered to the inner wall of the reaction kettle, the reaction kettle cannot be cleaned, the reactor can only be frequently replaced, the production cannot be continuously carried out, the production efficiency is low, and the cost is high; secondly, at high temperature, the gaseous magnesium and the solid tantalum pentoxide can only react on the surface of the tantalum pentoxide, the gas-solid reaction is incomplete, and the obtained tantalum powder contains a certain amount of tantalum oxide which is not completely reduced.
Disclosure of Invention
In view of the problems of the prior art, the invention provides a method for preparing high-purity ultrafine spherical tantalum powder, and the spherical tantalum powder prepared by the method has a particle size of between 100 and 200 nm.
In order to achieve the purpose, the invention adopts the technical scheme that: high-purity and superfine metal tantalum powder is used as a binary synergistic reducing agent, high-purity and superfine metal tantalum powder is used as a heat absorption medium, a heat conduction medium and a position resistance agent in an auxiliary mode, the high-purity and superfine tantalum pentoxide is completely reduced by two-step or three-step sintering, then generated magnesium oxide and redundant unreacted metal magnesium/magnesium nitride are dissolved by dilute acid solution, and the high-purity and superfine metal tantalum powder is obtained through washing and drying.
Ta2O5+Mg3N2＝2Ta+5MgO+1.667N2(g)
From the above thermodynamic data, the heat release (-210.160kJ) for the reduction of tantalum pentoxide with magnesium nitride at 800 ℃ is much less than the heat release (-1022.573kJ) for the reduction of tantalum pentoxide with magnesium metal. The AG value (-499.306kJ) is also less than the AG value (-850.310kJ) for magnesium metal to reduce tantalum pentoxide, so the reaction rate is also less than the reaction for magnesium metal as a reducing agent to reduce tantalum pentoxide.
The magnesium nitride acts as a synergistic reducing agent which simultaneously increases and adjusts the nitrogen content in the metallic tantalum powder due to the higher nitrogen content in the metallic tantalum powder required for high voltage tantalum capacitors.
Because the market price of magnesium nitride is higher than that of metal magnesium, the magnesium nitride and metal magnesium binary synergistic reducing agent is adopted, the reducing capability of the metal magnesium is stronger, and the oxygen content in the product is lower. The magnesium oxide formed can be easily removed by dilute mixed acid.
In the first step of reaction, part of metal tantalum powder is added as a heat absorption and heat conduction medium. In addition, the added tantalum powder has steric hindrance delay effect on the reaction of the magnesium powder and the tantalum pentoxide.
The three-step reduction method comprises the following specific steps:
(1) high-purity (more than 99.99%) tantalum pentoxide powder, micron-sized high-purity (more than 99.99%) magnesium nitride and metal magnesium powder are used as reactants, micron-sized high-purity (more than 99.99%) tantalum powder is used as a heat absorbing and conducting medium, and the molar ratio of the tantalum pentoxide to the tantalum powder to the magnesium nitride to the magnesium powder is 1: 0.1-0.8: 1/6-10/9: 0-5/4. The reaction exotherm of the magnesium nitride and the tantalum pentoxide is small, and the total exotherm of the reaction is small when the addition of the magnesium powder in the first step is small or not. The magnesium and the tantalum do not form an alloy phase, and the tantalum powder added at the same time greatly improves the heat conduction rate of the material.
(2) The rotary kiln is used to conduct the heat of the magnesium thermal reduction reaction to the metal hearth in time. The metal hearth is made of 310S stainless steel, and a high-purity tantalum plate is attached to the surface of the metal hearth. After the materials are mixed and ground, the materials are put into a dynamic sintering rotary kiln, the rotary kiln is vacuumized, high-purity (more than 99.999 percent) argon is filled, after the materials are repeatedly replaced for three times, the hearth of the rotary kiln is completely sealed under the vacuum condition or the temperature is slowly raised under the protection of inert gas, and the rotary kiln continuously rotates to enable the materials to rotate. The high temperature of the first step sintering is 500-600 ℃, and the temperature is kept for 2-10 hours. After cooling to room temperature, all material was aspirated in vacuo.
(3) The second step does not add tantalum pentoxide, but the second addition of magnesium nitride and magnesium powder is based on the tantalum pentoxide added in the first step, the molar ratio of the tantalum pentoxide to the magnesium nitride to the magnesium powder is 1: 0-5/6: 0-5/2, the magnesium nitride and the primarily reacted materials in the first step are ground together by a dry method, then the materials are put into a dynamic sintering rotary kiln, the rotary kiln is vacuumized, high-purity (more than 99.999 percent) argon is filled, after the three times of replacement, the hearth of the rotary kiln is completely sealed under the vacuum condition or the temperature is slowly raised under the protection of inert gas, and the rotary kiln continuously rotates to enable the materials to rotate. The maximum temperature is 650-. After cooling to room temperature, all material was aspirated in vacuo.
(4) In the third step, tantalum pentoxide is not added, but the third step of adding magnesium nitride and magnesium powder is carried out, wherein the molar ratio of tantalum pentoxide to magnesium nitride to magnesium powder is 1: 0-5/6: 0-10/3 based on the amount of tantalum pentoxide added in the first step. The total amount of the high-purity magnesium nitride and the high-purity magnesium powder added for three times is 1.1 to 1.5 times of the stoichiometric amount required for the complete reduction reaction of the tantalum pentoxide, and the excess amount of the reducing agent is 10 to 50 percent. And (3) grinding the added magnesium nitride and magnesium powder and the partially reacted material in the step (2) together by a dry method, loading into a dynamic sintering rotary kiln, vacuumizing, filling high-purity (more than 99.999%) argon, repeatedly replacing for three times, completely sealing the hearth of the rotary kiln under the vacuum condition or slowly heating under the protection of inert gas, and continuously rotating the rotary kiln to rotate the material. The maximum temperature is 850-. After cooling to room temperature, all material was aspirated in vacuo and dry ground.
(5) Slowly adding the ground powder in the step (4) into dilute acid solution, heating, continuously stirring for reaction, and soaking and standing the excessive powder in excessive acid solution to completely dissolve the generated MgO and excessive unreacted metal magnesium and magnesium nitride.
(6) Centrifugally drying, and washing with high-purity water for three times. And (5) drying in vacuum to obtain the high-purity superfine spherical tantalum powder. The two-step reduction method comprises the following specific steps:
(1) high-purity (more than 99.99%) tantalum pentoxide powder, micron-sized high-purity (more than 99.99%) magnesium nitride and metal magnesium powder are used as reactants, micron-sized high-purity (more than 99.99%) tantalum powder is used as a heat absorbing and conducting medium, and the molar ratio of the tantalum pentoxide to the tantalum powder to the magnesium nitride to the magnesium powder is 1: 0-0.8: 1/3-10/9: 0-5/4. The reaction exotherm of the magnesium nitride and the tantalum pentoxide is small, and the total exotherm of the reaction is small when the addition of the magnesium powder in the first step is small or not. The magnesium and the tantalum do not form an alloy phase, and the tantalum powder added at the same time greatly improves the heat conduction rate of the material. In the first step of reduction reaction, tantalum powder can be omitted when magnesium powder is omitted, and because only magnesium nitride reacts with tantalum pentoxide, the heat release amount is small, the reaction speed is slow, and the tantalum powder is not required to absorb and conduct heat.
(2) The rotary kiln is used to conduct the heat of the magnesium thermal reduction reaction to the metal hearth in time. The metal hearth is made of 310S stainless steel, and a high-purity tantalum plate is attached to the surface of the metal hearth. After the materials are mixed and ground, the materials are put into a dynamic sintering rotary kiln, the rotary kiln is vacuumized, high-purity (more than 99.999 percent) argon is filled, after the materials are repeatedly replaced for three times, the hearth of the rotary kiln is completely sealed under the vacuum condition or the temperature is slowly raised under the protection of inert gas, and the rotary kiln continuously rotates to enable the materials to rotate. The first step of sintering is 600-700 ℃, and the temperature is kept for 2-10 hours. After cooling to room temperature, all material was aspirated in vacuo.
(3) The second step does not add tantalum pentoxide, but the second addition of magnesium nitride and magnesium powder is based on the tantalum pentoxide added in the first step, and the molar ratio of tantalum pentoxide to magnesium nitride to magnesium powder is 1: 1/3-5/6: 5/4-5/2. The total amount of the high-purity magnesium nitride and the high-purity magnesium powder added in the two steps is 1.1 to 1.5 times of the stoichiometric amount required for the complete reduction reaction of the tantalum pentoxide, and the excess amount of the reducing agent is 10 to 50 percent. And (3) grinding the added magnesium nitride and magnesium powder and the partially reacted material in the step (2) together by a dry method, loading into a dynamic sintering rotary kiln, vacuumizing, filling high-purity (more than 99.999%) argon, repeatedly replacing for three times, completely sealing the hearth of the rotary kiln under the vacuum condition or slowly heating under the protection of inert gas, and continuously rotating the rotary kiln to rotate the material. The sintering temperature is 850 ℃ and 900 ℃, and the temperature is kept for 2-10 hours. After cooling to room temperature, all material was aspirated in vacuo and dry ground.
(4) Slowly adding the ground powder in the step (3) into dilute acid solution, heating, continuously stirring for reaction, and soaking and standing the excessive powder in excessive acid solution to completely dissolve the generated MgO and excessive unreacted metal magnesium and magnesium nitride.
(5) Centrifugally drying, and washing with high-purity water for three times. And (5) drying in vacuum to obtain the high-purity superfine spherical tantalum powder.
Specific examples of a method for preparing high purity ultra fine spherical tantalum powder according to the present invention are described in detail below to more fully illustrate some of the features and advantages of the present invention. It should be understood that these embodiments are merely illustrative, and the scope of the present invention is not limited thereto.
Example 1
10kg of nano tantalum pentoxide powder with the purity of 99.995 percent is taken, 2.54kg of micron-sized (d50 is 5.5um) high-purity magnesium nitride powder is added, 0.409kg of high-purity (more than 99.99 percent) ultrafine (d50 is 1.5um) tantalum powder is added, and the materials are mixed and ground for 30 minutes by using a grinding ball wrapped with polyurethane and a vibration ball mill internally coated with polyurethane. After the powder is sucked out, the powder is loaded into a hearth of the rotary kiln. The hearth of the rotary kiln is made of 310S stainless steel and internally laminated high-purity tantalum plates. Vacuumizing, filling high-purity (more than 99.999%) argon, repeatedly replacing for three times, and completely sealing the rotary kiln chamber under the condition of vacuumizing. Slowly heating at a heating rate of 2 ℃/min, and continuously rotating the rotary kiln to rotate the material at a rotating speed of 5 revolutions per minute. Raising the temperature to 500 ℃, and preserving the temperature for 10 hours. After cooling to room temperature, all the materials are sucked out in vacuum, then 0.917kg of high-purity magnesium powder is added for dry grinding for 10 minutes, all the powder materials are sucked out and put into a hearth of a rotary kiln. Vacuumizing, filling high-purity (more than 99.999%) argon, repeatedly replacing for three times, and completely sealing the rotary kiln chamber under the condition of vacuumizing. Slowly heating at a heating rate of 2 ℃/min, and continuously rotating the rotary kiln to rotate the material at a rotating speed of 5 revolutions per minute. The temperature is kept at 650 ℃ for 8 hours. After cooling to room temperature, all the materials are sucked out in vacuum, 1.375kg of high-purity magnesium powder is added for dry grinding for 10 minutes, all the powder is sucked out and is filled into a hearth of a rotary kiln. Vacuumizing, filling high-purity (more than 99.999%) argon, repeatedly replacing for three times, and completely sealing the rotary kiln chamber under the condition of vacuumizing. Slowly heating at a heating rate of 2 ℃/min, and continuously rotating the rotary kiln to rotate the material at a rotating speed of 5 revolutions per minute. The maximum temperature is 850 ℃, and the temperature is kept for 3 hours. Cooling to room temperature, sucking out all materials in vacuum, grinding for 10 minutes by a dry method, slowly adding the powder into a mixed acid solution of dilute hydrochloric acid and dilute nitric acid, heating to 70 ℃, continuously stirring and reacting for 2 hours until the total acid solution is excessive by 30 percent, and soaking for 8 hours to completely dissolve the generated MgO and excessive unreacted metal magnesium. The mixture was centrifuged and washed three times with 14M of high-purity water. Drying for 10 hours at the temperature of 85 ℃ in vacuum to obtain the high-purity superfine spherical tantalum powder. The XRD detection shows that the tantalum is a single pure phase, and the particle size of the spherical tantalum particles is about 110nm through the observation of a scanning electron microscope. ICP detection shows that the purity of the prepared tantalum powder is more than 99.99%.
Example 2
10kg of nano tantalum pentoxide powder with the purity of 99.995 percent is taken, 1.27kg of micron-sized (d50 is 2.5um) high-purity magnesium nitride powder is added, 1.227kg of high-purity (more than 99.99 percent) superfine tantalum powder is added, 0.344kg of micron-sized (d50 is 3.5um) high-purity magnesium powder is added, and polyurethane-coated grinding balls and a polyurethane-coated vibration ball mill are used for mixing and grinding for 20 minutes. After the powder is sucked out, the powder is loaded into a hearth of the rotary kiln. The hearth of the rotary kiln is made of 310S stainless steel and internally laminated high-purity tantalum plates. Vacuumizing, filling high-purity (more than 99.999 percent) argon, repeatedly replacing for three times, slowly heating under the protection of argon gas, wherein the heating rate is 2 ℃/min, continuously rotating the rotary kiln to rotate the material, and the rotating speed is 4 r/min. Raising the temperature to 550 ℃, and preserving the heat for 5 hours. After cooling to room temperature, all the materials are sucked out in vacuum, 1.904kg of high-purity magnesium nitride powder is added, 0.458kg of high-purity magnesium powder is added for dry grinding for 10 minutes, all the powder is sucked out and is filled into a hearth of a rotary kiln. Vacuumizing, filling high-purity (more than 99.999 percent) argon, repeatedly replacing for three times, slowly heating under the protection of argon gas, wherein the heating rate is 2 ℃/min, continuously rotating the rotary kiln to rotate the material, and the rotating speed is 4 r/min. The temperature is kept at the maximum temperature of 700 ℃ for 3 hours. After cooling to room temperature, all the materials are sucked out in vacuum, 0.458kg of high-purity magnesium powder is added for 10 minutes of dry grinding, all the powder is sucked out and is filled into a hearth of a rotary kiln. Vacuumizing, filling high-purity (more than 99.999 percent) argon, repeatedly replacing for three times, slowly heating under the protection of argon gas, wherein the heating rate is 2 ℃/min, continuously rotating the rotary kiln to rotate the material, and the rotating speed is 4 r/min. The temperature is kept for 2 hours at the maximum temperature of 900 ℃. Cooling to room temperature, vacuum-pumping out all materials, dry-grinding for 10 min, slowly adding the powder into 15% dilute nitric acid solution, heating to 70 deg.C, continuously stirring and reacting for 4 hr until the total acid solution is 25% excessive, and soaking for 10 hr to completely dissolve the generated MgO and excessive unreacted metal magnesium. The mixture was centrifuged and washed three times with 14M of high-purity water. Drying for 10 hours at the temperature of 85 ℃ in vacuum to obtain the high-purity superfine spherical tantalum powder. The XRD detection shows that the tantalum is a single pure phase, and the particle size of the spherical tantalum particles is about 120nm when the spherical tantalum particles are observed by a scanning electron microscope. ICP detection shows that the purity of the prepared tantalum powder is more than 99.99%.
Example 3
10kg of nano tantalum pentoxide powder with the purity of 99.995 percent is taken, 0.635kg of micron-sized high-purity magnesium nitride is added, 0.688kg of micron-sized (d50 is 13.5um) high-purity magnesium powder is added, 2.045kg of high-purity (more than 99.99 percent) superfine tantalum powder is added, and polyurethane-coated grinding balls and a polyurethane-coated vibration ball mill are used for mixing and grinding for 15 minutes. After the powder is sucked out, the powder is loaded into a hearth of the rotary kiln. The hearth of the rotary kiln is made of 310S stainless steel and internally laminated high-purity tantalum plates. Vacuumizing, filling high-purity (more than 99.999 percent) argon, repeatedly replacing for three times, slowly heating under the protection of argon gas, wherein the heating rate is 2 ℃/min, continuously rotating the rotary kiln to rotate the material, and the rotating speed is 5 r/min. The temperature is raised to 600 ℃ and the temperature is preserved for 4 hours. Cooling to room temperature, vacuum sucking out all materials, adding micron-sized high-purity magnesium nitride 1.27kg, adding high-purity magnesium powder 0.688kg, dry grinding for 15 min, sucking out powder, and loading into the hearth of a rotary kiln. Vacuumizing, filling high-purity (more than 99.999 percent) argon, repeatedly replacing for three times, slowly heating under the protection of argon gas, wherein the heating rate is 2 ℃/min, continuously rotating the rotary kiln to rotate the material, the rotating speed is 5 r/min, the highest temperature is 700 ℃, and keeping the temperature for 3 hours. Cooling to room temperature, vacuum sucking out all the materials, adding 0.275kg of high-purity magnesium powder, dry grinding for 15 minutes, sucking out powder, and filling into a hearth of a rotary kiln. Vacuumizing, filling high-purity (more than 99.999 percent) argon, repeatedly replacing for three times, completely sealing the hearth of the rotary kiln under the condition of vacuumizing, slowly heating, wherein the heating rate is 2 ℃/min, continuously rotating the rotary kiln to rotate the material, and the rotating speed is 5 r/min. The temperature is kept for 2 hours at the maximum temperature of 900 ℃. Cooling to room temperature, vacuum-pumping out all materials, grinding for 15 minutes by a dry method, slowly adding the powder into 15% dilute hydrochloric acid, heating to 75 ℃, continuously stirring and reacting for 3 hours until the total acid liquor is excessive by 20%, and soaking for 6 hours to completely dissolve the generated MgO and excessive unreacted metal magnesium. The mixture was centrifuged and washed three times with 14M of high-purity water. Drying for 10 hours at the temperature of 85 ℃ in vacuum to obtain the high-purity superfine spherical tantalum powder. The XRD detection shows that the tantalum is a single pure phase, and the particle size of the spherical tantalum particles is about 150nm when the spherical tantalum particles are observed by a scanning electron microscope. ICP detection shows that the purity of the prepared tantalum powder is more than 99.99%.
Example 4
10kg of nano tantalum pentoxide powder with the purity of 99.995 percent is taken, 0.381kg of micron-sized high-purity magnesium nitride is added, 0.458kg of micron-sized (d50 is 3.5um) high-purity magnesium powder is added, 3.272kg of high-purity (more than 99.99 percent) superfine tantalum powder is added, and polyurethane-coated grinding balls and a polyurethane-coated vibration ball mill are used for mixing and grinding for 12 minutes. After the powder is sucked out, the powder is loaded into a hearth of the rotary kiln. The hearth of the rotary kiln is made of 310S stainless steel and internally laminated high-purity tantalum plates. Vacuumizing, filling high-purity (more than 99.999%) argon, repeatedly replacing for three times, and completely sealing the rotary kiln chamber under the condition of vacuumizing. Slowly heating at a heating rate of 1 ℃/min, and continuously rotating the rotary kiln to rotate the material at a rotating speed of 6 revolutions per minute. Raising the temperature to 500 ℃, and preserving the heat for 6 hours. Cooling to room temperature, vacuum sucking out all materials, adding 1.375g of high-purity magnesium powder, dry grinding for 12 minutes, sucking out all powder, and then loading into a hearth of a rotary kiln. Vacuumizing, filling high-purity (more than 99.999%) argon, repeatedly replacing for three times, and completely sealing the rotary kiln chamber under the condition of vacuumizing. Slowly heating at a heating rate of 1 ℃/min, continuously rotating the rotary kiln to rotate the material at a rotating speed of 6 revolutions per minute and a maximum temperature of 650 ℃, and keeping the temperature for 5 hours. Cooling to room temperature, vacuum sucking out all the materials, adding 1.375kg of high-purity magnesium powder, dry grinding for 12 minutes, sucking out all the powder, and loading into the hearth of a rotary kiln. Vacuumizing, filling high-purity (more than 99.999%) argon, repeatedly replacing for three times, and completely sealing the rotary kiln chamber under the condition of vacuumizing. Slowly heating at a heating rate of 1 ℃/min, continuously rotating the rotary kiln to rotate the material at a rotating speed of 6 revolutions per minute and a maximum temperature of 850 ℃, and keeping the temperature for 4 hours. Cooling to room temperature, sucking out all materials in vacuum, grinding for 12 minutes by a dry method, slowly adding the powder into a mixed acid solution of 10% dilute hydrochloric acid and 15% dilute nitric acid, heating to 75 ℃, continuously stirring and reacting for 3 hours until the total acid solution is 15% excessive, and soaking for 4 hours to completely dissolve the generated MgO and excessive unreacted metal magnesium. The mixture was centrifuged and washed three times with 14M of high-purity water. Drying for 10 hours at the temperature of 85 ℃ in vacuum to obtain the high-purity superfine spherical tantalum powder. XRD detects that the tantalum is a single pure phase, and the particle size of spherical tantalum particles is about 200nm when the spherical tantalum particles are observed by a scanning electron microscope. ICP detection shows that the purity of the prepared tantalum powder is more than 99.99%.
Example 5
10kg of nano tantalum pentoxide powder with the purity of 99.995 percent is taken, 2.54kg of micron-sized (d50 is 5.5um) high-purity magnesium nitride powder is added, 0.688kg of high-purity magnesium powder is added, 0.409kg of high-purity (more than 99.99 percent) ultrafine (d50 is 1.5um) tantalum powder is added, and polyurethane-coated grinding balls and a polyurethane-coated vibration ball mill are used for mixing and grinding for 30 minutes. After the powder is sucked out, the powder is loaded into a hearth of the rotary kiln. The hearth of the rotary kiln is made of 310S stainless steel and internally laminated high-purity tantalum plates. Vacuumizing, filling high-purity (more than 99.999%) argon, repeatedly replacing for three times, and completely sealing the rotary kiln chamber under the condition of vacuumizing. Slowly heating at a heating rate of 1 ℃/min, and continuously rotating the rotary kiln to rotate the material at a rotating speed of 7 revolutions per minute. Raising the temperature to 600 ℃, and preserving the temperature for 10 hours. After cooling to room temperature, all the materials are sucked out in vacuum, then 0.761kg of high-purity magnesium nitride powder is added, 0.688kg of high-purity magnesium powder is added for dry grinding for 10 minutes, all the powder materials are sucked out and are filled into a hearth of a rotary kiln. Vacuumizing, filling high-purity (more than 99.999%) argon, repeatedly replacing for three times, and completely sealing the rotary kiln chamber under the condition of vacuumizing. Slowly heating at a heating rate of 1 ℃/min, and continuously rotating the rotary kiln to rotate the material at a rotating speed of 7 revolutions per minute. The maximum temperature is 850 ℃, and the temperature is kept for 8 hours. Cooling to room temperature, sucking out all materials in vacuum, grinding for 10 minutes by a dry method, slowly adding the powder into a mixed acid solution of 15% dilute hydrochloric acid and 10% dilute nitric acid, heating to 70 ℃, continuously stirring and reacting for 2 hours, wherein the total acid solution is excessive by 30%, and soaking for 8 hours to completely dissolve the generated MgO and excessive unreacted metal magnesium. The mixture was centrifuged and washed three times with 14M of high-purity water. Drying for 10 hours at the temperature of 85 ℃ in vacuum to obtain the high-purity superfine spherical tantalum powder. The XRD detection shows that the tantalum is a single pure phase, and the particle size of the spherical tantalum particles is about 150nm when the spherical tantalum particles are observed by a scanning electron microscope. ICP detection shows that the purity of the prepared tantalum powder is more than 99.99%.
Example 6
10kg of nano-grade tantalum pentoxide powder with the purity of 99.995 percent is taken, 2.54kg of micron-grade (d50 is 5.5um) high-purity magnesium nitride powder is added, and the mixture is mixed and ground for 20 minutes by using a polyurethane-coated grinding ball and a polyurethane-coated vibration ball mill. After the powder is sucked out, the powder is loaded into a hearth of the rotary kiln. The hearth of the rotary kiln is made of 310S stainless steel and internally laminated high-purity tantalum plates. Vacuumizing, filling high-purity (more than 99.999%) argon, repeatedly replacing for three times, and completely sealing the rotary kiln chamber under the condition of vacuumizing. Slowly heating at a heating rate of 2 ℃/min, and continuously rotating the rotary kiln to rotate the material at a rotating speed of 4 revolutions per minute. Raising the temperature to 650 ℃, and preserving the temperature for 5 hours. After cooling to room temperature, all the materials are sucked out in vacuum, 1.904kg of high-purity magnesium nitride powder is added, 0.688kg of high-purity magnesium powder is added for dry grinding for 15 minutes, all the powder materials are sucked out and are filled into a hearth of a rotary kiln. Vacuumizing, filling high-purity (more than 99.999%) argon, repeatedly replacing for three times, and completely sealing the rotary kiln chamber under the condition of vacuumizing. Slowly heating at a heating rate of 2 ℃/min, and continuously rotating the rotary kiln to rotate the material at a rotating speed of 8 revolutions per minute. The temperature is kept for 3 hours at the maximum temperature of 900 ℃. Cooling to room temperature, sucking out all materials in vacuum, grinding for 15 minutes by a dry method, slowly adding the powder into a mixed acid solution of 15% dilute hydrochloric acid and 15% dilute nitric acid, heating to 80 ℃, continuously stirring and reacting for 4 hours until the total acid solution is 25% excessive, and soaking for 10 hours to completely dissolve the generated MgO and excessive unreacted metal magnesium. The mixture was centrifuged and washed three times with 14M of high-purity water. Drying for 10 hours at the temperature of 85 ℃ in vacuum to obtain the high-purity superfine spherical tantalum powder. XRD detects that the tantalum is a single pure phase, and the particle size of the spherical tantalum particles is about 130nm when observed by a scanning electron microscope. ICP detection shows that the purity of the prepared tantalum powder is more than 99.99%.
Example 7
10kg of nano tantalum pentoxide powder with the purity of 99.995 percent is taken, 1.27kg of micron-sized high-purity magnesium nitride is added, 0.688kg of micron-sized (d50 is 3.5um) high-purity magnesium powder is added, 1.227kg of high-purity (more than 99.99 percent) superfine tantalum powder is added, and polyurethane-coated grinding balls and a vibration ball mill internally coated with polyurethane are used for mixing and grinding for 15 minutes. After the powder is sucked out, the powder is loaded into a hearth of the rotary kiln. The hearth of the rotary kiln is made of 310S stainless steel and internally laminated high-purity tantalum plates. Vacuumizing, filling high-purity (more than 99.999%) argon, repeatedly replacing for three times, and completely sealing the rotary kiln chamber under the condition of vacuumizing. Slowly heating at a heating rate of 1 ℃/min, and continuously rotating the rotary kiln to rotate the material at a rotating speed of 7 revolutions per minute. The temperature is raised to 700 ℃ and the temperature is kept for 2 hours. Cooling to room temperature, vacuum sucking out all materials, adding 1.27kg of micron-sized high-purity magnesium nitride, adding 1.375kg of high-purity magnesium powder, grinding for 15 minutes by a dry method, sucking out powder, and then loading into a hearth of a rotary kiln. Vacuumizing, filling high-purity (more than 99.999%) argon, repeatedly replacing for three times, and completely sealing the rotary kiln chamber under the condition of vacuumizing. Slowly heating at a heating rate of 1 ℃/min, continuously rotating the rotary kiln to rotate the material at a rotation speed of 7 revolutions per minute and a maximum temperature of 900 ℃, and keeping the temperature for 2 hours. Cooling to room temperature, sucking out all materials in vacuum, grinding for 15 minutes by a dry method, slowly adding the powder into a mixed acid solution of dilute hydrochloric acid and dilute nitric acid, heating to 75 ℃, continuously stirring and reacting for 3 hours until the total acid solution is excessive by 20 percent, and soaking for 6 hours to completely dissolve the generated MgO and excessive unreacted metal magnesium. The mixture was centrifuged and washed three times with 14M of high-purity water. Drying for 10 hours at the temperature of 85 ℃ in vacuum to obtain the high-purity superfine spherical tantalum powder. The XRD detection shows that the tantalum is a single pure phase, and the particle size of the spherical tantalum particles is about 190nm through the observation of a scanning electron microscope. ICP detection shows that the purity of the prepared tantalum powder is more than 99.99%.
Example 8
10kg of nano tantalum pentoxide powder with the purity of 99.995 percent is taken, 0.761kg of micron-sized high-purity magnesium nitride is added, 1.375kg of micron-sized (d50 is 3.5um) high-purity magnesium powder is added, 3.272kg of high-purity (more than 99.99 percent) superfine tantalum powder is added, and polyurethane-coated grinding balls and a polyurethane-coated vibration ball mill are used for mixing and grinding for 12 minutes. After the powder is sucked out, the powder is loaded into a hearth of the rotary kiln. The hearth of the rotary kiln is made of 310S stainless steel and internally laminated high-purity tantalum plates. Vacuumizing, filling high-purity (more than 99.999%) argon, repeatedly replacing for three times, and completely sealing the rotary kiln chamber under the condition of vacuumizing. Slowly heating at a heating rate of 1 ℃/min, and continuously rotating the rotary kiln to rotate the material at a rotating speed of 7 revolutions per minute. Raising the temperature to 600 ℃, and preserving the temperature for 5 hours. After cooling to room temperature, all materials are sucked out in vacuum, 0.761kg of high-purity magnesium nitride and 0.917g of high-purity magnesium powder are added, dry grinding is carried out for 12 minutes, all powder materials are sucked out and then are loaded into a hearth of a rotary kiln. Vacuumizing, filling high-purity (more than 99.999%) argon, repeatedly replacing for three times, and completely sealing the rotary kiln chamber under the condition of vacuumizing. Slowly heating at a heating rate of 1 ℃/min, continuously rotating the rotary kiln to rotate the material at a rotation speed of 7 revolutions per minute and a maximum temperature of 900 ℃, and keeping the temperature for 2 hours. Cooling to room temperature, sucking out all materials in vacuum, grinding for 12 minutes by a dry method, slowly adding the powder into a mixed acid solution of dilute hydrochloric acid and dilute nitric acid, heating to 75 ℃, continuously stirring and reacting for 3 hours until the total acid solution is 15% excessive, and soaking for 4 hours to completely dissolve the generated MgO and excessive unreacted metal magnesium. The mixture was centrifuged and washed three times with 14M of high-purity water. Drying for 10 hours at the temperature of 85 ℃ in vacuum to obtain the high-purity superfine spherical tantalum powder. The XRD detection shows that the tantalum is a single pure phase, and the particle size of the spherical tantalum particles is about 180nm when the spherical tantalum particles are observed by a scanning electron microscope. ICP detection shows that the purity of the prepared tantalum powder is more than 99.99%.
When the materials are prepared for the first time, if only the magnesium nitride reducing agent is added, but the metal magnesium powder reducing agent is not added, the metal tantalum powder can not be added. When a certain amount of metal magnesium powder is added during the first batching, part of tantalum powder is needed to be added to promote the conduction of reaction heat, otherwise, thermal runaway easily occurs during the magnesium thermal reaction, and the phenomena of abnormal growth and melting connection of tantalum particles, impurity peritectic formation and the like are caused. To verify the important role of part of the tantalum powder added at the first dosing, comparative example 1 was made as follows in comparison with example 8.
Comparative example 1
10kg of nano tantalum pentoxide powder with the purity of 99.995 percent is taken, 0.761kg of micron-sized high-purity magnesium nitride is added, 1.375kg of micron-sized (d50 is 3.5um) high-purity magnesium powder is added, and high-purity superfine tantalum powder is not added. The mixture was ground for 12 minutes using polyurethane coated grinding balls, a polyurethane coated internally vibratory ball mill. After the powder is sucked out, the powder is loaded into a hearth of the rotary kiln. The hearth of the rotary kiln is made of 310S stainless steel and internally laminated high-purity tantalum plates. Vacuumizing, filling high-purity (more than 99.999%) argon, repeatedly replacing for three times, and completely sealing the rotary kiln chamber under the condition of vacuumizing. The rotary kiln was rotated continuously to rotate the material at 7 rpm. The temperature is slowly increased, the temperature increase rate is 1 ℃/min, when the temperature of the furnace is increased to 553 ℃, the violent magnesium thermal reduction reaction is generated in the hearth, and the temperature thermocouple on the outer wall of the hearth of the furnace displays that the temperature is increased to 890 ℃ in a very short time. The strong heat release of the reaction also promotes the reaction to be accelerated, thereby releasing more heat, and releasing a large amount of heat in a very short time to ensure that the temperature of the materials and the hearth is increased sharply. And (3) turning off a heating power supply in an emergency, rapidly rotating the furnace tank, slowly cooling to room temperature, and opening the furnace cover to find that a lot of powder is adhered to the inner wall of the hearth and other powder is seriously agglomerated. The caked material was poured out, crushed with a heavy hammer, and then dry-vibrationally ground with a vibratory ball mill (phi 15+ phi 5 zirconia balls) for 2 hours, and then passed through a 200-mesh screen with a throughput of only 55 wt%, leaving 45 wt% of the caked material that did not pass through the 200-mesh screen as a particularly hard black caked material. This is the incomplete reduction product of tantalum pentoxide with magnesium and remains the oxide of tantalum. The observation of a scanning electron microscope shows that the particles are completely melted to form aggregates, and the high-purity superfine metal tantalum powder cannot be obtained. The experimental phenomenon and the experimental results are completely different from those of example 8.
3.272kg of high purity (> 99.99%) ultra fine micron tantalum powder was added to the first batch in example 8. Tantalum pentoxide is an oxide and is not thermally conductive. The metal tantalum powder has very good thermal conductivity, plays the key roles of heat absorption and heat conduction and radiation, and ensures that heat released by magnesium thermal reaction generated during slow temperature rise can be timely transmitted to a rotating metal hearth to be absorbed, so that the temperature of a reaction system is in a controllable range. In addition, the added tantalum powder has steric hindrance delay effect on the reaction of the magnesium powder and the tantalum pentoxide.
Part of the magnesium nitride added during the material preparation is because the magnesium nitride and the tantalum pentoxide have small heat release and slow reaction speed during the reduction reaction, so as to control the total heat release and the reaction speed of the reaction and obtain the superfine metal tantalum powder. To verify the important role of part of the magnesium nitride added at the first dosing, comparative example 2 was made as follows in comparison with example 7.
Comparative example 2
10kg of nano tantalum pentoxide powder with the purity of 99.995 percent is taken, high-purity magnesium nitride powder is not added, 0.688kg of micron-sized (d50 is 3.5um) high-purity magnesium powder is added, 1.227kg of high-purity (more than 99.99 percent) superfine tantalum powder is added, and polyurethane-coated grinding balls and a polyurethane-coated vibration ball mill are used for mixing and grinding for 15 minutes. After the powder is sucked out, the powder is loaded into a hearth of the rotary kiln. The hearth of the rotary kiln is made of 310S stainless steel and internally laminated high-purity tantalum plates. Vacuumizing, filling high-purity (more than 99.999%) argon, repeatedly replacing for three times, and completely sealing the rotary kiln chamber under the condition of vacuumizing. Slowly heating at a heating rate of 1 ℃/min, and continuously rotating the rotary kiln to rotate the material at a rotating speed of 7 revolutions per minute. The temperature is slowly increased with the temperature increase rate of 1 ℃/min. When the temperature rises to 512 ℃, a violent magnesiothermic reduction reaction occurs in the hearth, and the temperature thermocouple on the outer wall of the hearth of the kiln shows that the temperature rises to 910 ℃ in a very short time. The strong heat release of the reaction also promotes the reaction to be accelerated, thereby releasing more heat, and releasing a large amount of heat in a very short time to ensure that the temperature of the materials and the hearth is increased sharply. And (3) turning off a heating power supply in an emergency, rapidly rotating the furnace tank, slowly cooling to room temperature, and opening the furnace cover to find that a lot of powder is adhered to the inner wall of the hearth and other powder is seriously agglomerated. The caked material was poured out, crushed with a heavy hammer, and dry-vibrationally ground with a vibratory ball mill (phi 15+ phi 5 zirconia balls) for 2 hours, and then passed through a 200-mesh screen with a throughput of only 42 wt%, leaving 58 wt% of the black caked material that did not pass through the 200-mesh screen as a particularly hard black caked material. This is the incomplete reduction product of tantalum pentoxide with magnesium and remains the oxide of tantalum. Sieving the powder, and observing by a scanning electron microscope to obtain micron-sized aggregates containing melt and unreacted substances. The high-purity superfine metal tantalum powder cannot be obtained.
Example 7 added a portion of the magnesium nitride reducing agent which reacted with tantalum pentoxide with a lower exotherm and a slower reaction rate. The synergistic effect of the reducing agent magnesium nitride and the metal magnesium powder ensures that the reaction is in a controllable range, thereby obtaining the high-purity superfine metal tantalum powder. In contrast to example 2, magnesium nitride is not added, only a magnesium metal reducing agent is added, and meanwhile, the addition amount of tantalum metal powder is small, the magnesium powder and tantalum pentoxide rapidly react to strongly release heat, the heat cannot be timely conducted to a furnace tube, thermal runaway occurs, and high-purity and superfine tantalum metal powder cannot be obtained. It is shown that magnesium nitride plays a decisive role in example 7.
TABLE 1 ICP test results for tantalum powder prepared in example 1
| Elemental impurities | Content (ppm) | |
| 1 | Fe | 8 |
| 2 | Ni | 3 |
| 3 | |
10 |
| 4 | Cr | 2 |
| 5 | |
10 |
| 6 | Ti | 3 |
| 7 | W | 3 |
| 8 | Mo | 5 |
| 9 | Mn | 5 |
| 10 |
Description of the drawings
FIG. 1 XRD patterns of tantalum powders prepared in example 1
FIG. 2 SEM photograph of tantalum powder prepared in example 1
FIG. 3 SEM photograph of tantalum powder prepared in example 2
FIG. 4 scanning Electron micrograph of sample prepared in comparative example 1
FIG. 5 scanning electron micrograph of sample prepared in comparative example 2.
Claims (6)
1. A method for manufacturing high-purity superfine spherical tantalum powder comprises the following steps: the high-purity superfine metal tantalum powder is used as a binary synergistic reducing agent, the high-purity superfine metal tantalum powder is used as a heat absorption medium, a heat conduction medium and a position resistance agent in an auxiliary mode, the high-purity superfine tantalum pentoxide is completely reduced by two-step or three-step sintering, then the generated magnesium oxide and the redundant unreacted metal magnesium/magnesium nitride are dissolved by dilute acid solution, and the high-purity superfine metal tantalum powder is obtained after washing and drying.
2. The high purity ultra fine magnesium nitride of claim 1, having a purity > 99.99% and a particle size d50 ≤ 25 μm;
high-purity superfine metal magnesium powder, the purity is more than 99.99 percent, and the grain diameter d50 is less than or equal to 25 mu m;
the purity of the high-purity superfine metal tantalum powder is more than 99.99 percent, and the particle size d50 is less than or equal to 10 mu m;
the high-purity superfine tantalum pentoxide has the purity of more than 99.99 percent and the grain diameter d50 of less than or equal to 20 mu m.
3. The two-step sintering according to claim 1, wherein: (1) the first step comprises the following ingredients: the mol ratio of tantalum pentoxide to tantalum powder to magnesium nitride to magnesium powder is 1: 0-0.8: 1/3-10/9: 0-5/4. Sintering the mixture in vacuum or under the protection of inert gas for the first step after ball milling, and keeping the temperature for 2 to 10 hours at the temperature of 600-700 ℃. And cooling and ball milling.
(2) The second step does not add tantalum pentoxide, and the second addition of magnesium nitride and magnesium powder is based on the tantalum pentoxide added in the first step, and the molar ratio of the tantalum pentoxide to the magnesium nitride to the magnesium powder is 1: 1/3-5/6: 5/4-5/2. The added magnesium nitride and magnesium powder and the partially reacted materials in the first step are ground together in a dry method and then sintered in a second step under vacuum or inert gas protection at the temperature of 850 ℃ and 900 ℃ for 2 to 10 hours. And cooling and ball milling.
4. The three-step sintering according to claim 1, characterized in that: (1) the first step comprises the following ingredients: the mol ratio of tantalum pentoxide to tantalum powder to magnesium nitride to magnesium powder is 1: 0.1-0.8: 1/6-10/9: 0-5/4. Sintering the mixture in vacuum or under the protection of inert gas for the first step after ball milling, keeping the temperature at 600 ℃ for 2 to 10 hours. And cooling and ball milling.
(2) The second step does not add tantalum pentoxide, and the second addition of magnesium nitride and magnesium powder is based on the tantalum pentoxide added in the first step, and the molar ratio of the tantalum pentoxide to the magnesium nitride to the magnesium powder is 1: 0-5/6: 0-5/2. The added magnesium nitride and magnesium powder are ground together with the partially reacted materials in the first step in a dry method, and then sintered in a second step under the protection of vacuum or inert gas, the temperature is 650-700 ℃, and the temperature is kept for 2-10 hours. And cooling and ball milling.
(3) In the third step, tantalum pentoxide is not added, but the third step of adding magnesium nitride and magnesium powder is carried out by taking the tantalum pentoxide added in the first step as a reference, and the molar ratio of the tantalum pentoxide to the magnesium nitride to the magnesium powder is 1: 0-5/6: 0-10/3. The added magnesium nitride and magnesium powder are ground together with the partially reacted materials in the second step in a dry method and then sintered in a third step under vacuum or inert gas protection at the temperature of 850 ℃ and 900 ℃ for 2 to 10 hours. And cooling and ball milling.
5. A dilute acid solution as claimed in claim 1, wherein the dilute acid solution is: one or more of hydrochloric acid, nitric acid and sulfuric acid.
6. Sintering according to claim 1, wherein the sintering is carried out in a dynamic or static kiln, preferably a dynamic rotary kiln.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115572843A (en) * | 2022-10-26 | 2023-01-06 | 江苏美特林科特殊合金股份有限公司 | Preparation method of high-purity metal tantalum |
| CN115572843B (en) * | 2022-10-26 | 2023-08-29 | 江苏美特林科特殊合金股份有限公司 | Preparation method of high-purity metal tantalum |
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Application publication date: 20220415 |