CN100340365C - Preparation of low-temperature primary sintering high-density superfine crystal particle pure tungsten material - Google Patents
Preparation of low-temperature primary sintering high-density superfine crystal particle pure tungsten material Download PDFInfo
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- CN100340365C CN100340365C CNB200410080350XA CN200410080350A CN100340365C CN 100340365 C CN100340365 C CN 100340365C CN B200410080350X A CNB200410080350X A CN B200410080350XA CN 200410080350 A CN200410080350 A CN 200410080350A CN 100340365 C CN100340365 C CN 100340365C
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Abstract
The present invention provides a preparation method for once sintering high density ultrafine grain pure tungsten materials and products at low temperature. 350 to 400 DEG C of high temperature, 5 to 6.5MPa of high pressure and a supersonic spray thermal conversion method are used, firstly, an aqueous solution of ammonium tungstate is prepared to be nanometer WO3 powder whose average grain size is less than or equal to 40 nm, and nanometer porous blue tungsten powder is prepared by repeated reduction, oxidation and reduction. Then, a furfural-phenolic aldehyde-propyl alcohol solution is added to the blue tungsten powder, and a furfural organic film is cladded on each blue tungsten grain by the stir and the mixture of double spiral stirring mixer. The blue tungsten powder is reduced to be tungsten powder whose average grain size is less than or equal to 70 nm in a rotary tubular continuous boiling furnace, and the nanometer tungsten powder is sheared with high energy and is activated in a dry high speed interlaminar shearer. The nanometer tungsten powder is formed by high pressure flexible molds and is prepared to be tungsten powder compacts, the tungsten powder compacts can be prepared to be the ultrafine grain pure tungsten materials whose relative density is from 95 to 96% after being once sintered in a molybdenum wire furnace at low temperature, and the average grain size of tungsten is less than or equal to 8 to 12 mum.
Description
Technical field
The invention belongs to refractory metal tungsten preparing technical field, a kind of low-temperature primary sintering high-density superfine crystal particle pure tungsten (W) preparation methods particularly is provided, be applicable to large-scale industrialization production.
Background technology
The fusing point of tungsten is up to 3410 ℃, and height ranks first in all metals, and more valuable is that its boiling point is 5527 ℃, and heat of evaporation is that any metal of 799.4 (J/mol) hardly matches.
The pure tungsten block materials still has the high-melting-point characteristic, high elevated temperature strength, and high elastic modulus, low-expansion coefficient reaches shielding and absorbent properties to radioactive ray.Because These characteristics has determined tungsten can become high temperature, the ultra-high temperature condition optimal material of use down, therefore tungsten extensively is used to make various electric glowers, the superhigh temperature electric heating element, and the heat-resisting part of superhigh temperature etc., as various electric lamp filaments, various picture tubes, the thermionic emission filament and the negative electrode of vacuum tube, the superhigh temperature heating, heat screen, rocket nozzle etc.
Every year only lighting filament domestic demand amount up to 450 tons.About 150 tons of tungsten heating (sheet material) year, about 170 tons of blunt tungsten ingot blank and massive article.In recent years along with hi-tech development to high performance tungsten plate, especially wide cut (＞700mm) large tracts of land book plate, super book paper tinsel band, high performance and long service life antidetonation tungsten filament increases etc. demand is anxious, use as DVD CD nickel plating tungsten boat high-quality tungsten sheet year requirement above 70 tons, the solid-rocket jet pipe throat lining, high temperature resistant nose cone, jet vane superhigh temperature transpiration material etc., war products year, requirement was above 50 tons.In recent years owing to have the conduction of excellence with the tungsten-copper alloy of tungsten powder preparation, characteristics such as the heat dissipation characteristics and the coefficient of expansion are adjustable, in large scale integrated circuit and HIGH-POWERED MICROWAVES device, be used to make substrate, heat pillow abaculus, devices such as encapsulation connector and heat dissipation element, improved the use power of microelectronic component greatly, can make device miniaturization, its coefficient of expansion can with the silicon chip in the microelectronic component, semi-conducting materials such as GaAs and base well mate with ceramic material, so be desirable encapsulating material.According to incomplete statistics in 2000,200～250 tons of the domestic year requirements of only this item.
China produces tungsten big country, more than 20,000 ton of thick tungsten product outlet arranged every year, each industrial power of the world is to be provided by China with 50% of tungsten amount, about 1000～1200 tons of the output of domestic pure tungsten metallic article, output is also at the forefront in the world, but on the production technology and intellectual property of high-quality tungsten material, China does not almost have in recent years has.Illustrate that new technology development is slower, but development of high-tech, requirement to pure tungsten and alloy material thereof is more and more high, other tungsten product section bar (as tungsten-copper composition, tungsten ferronickel high specific gravity goods etc.) that no matter to tungsten filament, sheet material, foil or with tungsten is matrix has proposed even tissue, the refinement of crystal grain ultra micro, the requirement of good plasticity.But production technology in the past is difficult to satisfy the modern high technology demand for development.In recent years at W-Ni-Fe, W-Ni-Cu high-density alloy, and the existing more research document in W-Cu alloy aspect, but the research aspect pure tungsten material is seldom.Prepare pure tungsten material as can be known at present by the long-term production experience and all adopt two key steps, the one, with the repressed one-tenth base of tungsten powder, 1600 ℃ of pre-burnings for the first time, 1980～2800 ℃ of incipient fusion sintering or vacuum-sinterings of superhigh temperature for the second time.It is further densified by various hot-working means under second step had been higher than 1200 ℃ then to make pure tungsten base material density reach relative density＞94～96% gradually, just can make final pure tungsten material or part.
By nearly 15 years relevant literature search as can be known, at present various countries are that the tungsten powder of 2～5 μ m is a material powder producing or all adopting particle diameter during the development pure tungsten material, tungsten grain in this tungsten powder since 800 ℃ up to 2800 ℃ in long sintering process, collective recrystallization is grown up fast always, cause the tungsten grain in the pure tungsten goods to be grown up to 200～400 μ m, be about 80～160 times of original tungsten grain by 2.5 μ m.
Therefore domestic and international existing pure tungsten material, at normal temperatures, without exception all belong to the very crisp metal material of performance.This deadly defect has had a strong impact on the range of application of pure tungsten material.For a long time, the pure tungsten material and the goods of ultra-fine grain are expected to obtain always by each industrial power of the world.Particularly abroad begin one's study in recent years with diamond super-pressure synthesis press, the technology of hot pressed sintering pure tungsten material under 980～1100 ℃ of super-pressure 2-2.5GPa of low temperature condition, the result shows, can obtain the superfine crystal particle pure tungsten sample that relative density 〉=97% average crystal grain is 30-50nm.But regrettably this method is difficult to produce larger-size goods, and production cost is too high, does not have the value of industrialization promotion.It seems at present how can with new vanguard technology, prepare ultra-fine grain under the current production devices condition, the pure tungsten goods of mean tungsten crystal grain≤8-12 μ m have been the heat subject that each industrial power extremely pays close attention to over past ten years.
Summary of the invention
The objective of the invention is to: a kind of low-temperature primary sintering high-density superfine crystal particle pure tungsten (W) preparation methods is provided, solves the problem that it is difficult that nanometer powder is shaped.
The present invention adopts supersonic speed to spray hot transformation approach with high concentration ammonium tungstate aqueous solution (its WO
3Content 350～370g/ liter) makes nanoscale (≤40nm) WO earlier
3Powder, the technology of the hot transformation approach of spraying is circumferential weld air-flow resonant mode superonic flow nozzzle for the nozzle that adopts, under 350～400 ℃ of hot blast temperatures, adopt high pressure (5～6.5MPa) air, jet velocity be 2～2.5 Mach of supersonic speed (664～830m/s), the nozzle of nozzle ejection angle α=50 °, short focal length F=11.5mm.Use H then
2With oxygen reduce repeatedly---oxidation---reduction, make the thinner tungsten powder of granularity.Add (furfural-phenolic aldehyde-propyl alcohol) solution with double-screw type stir mixing machine in tungsten powder, with blue tungsten particle, coat one deck furfural alcogel film, after the drying, with the rotary pipe type reduction furnace that seethes with excitement continuously, 740～760 ℃ of low temperature, 45～60 minutes with (H
2+ N
2) gas makes the tungsten powder of average grain diameter≤70nm with tungsten powder reduction, uses cutter between the dry type high-speed layer again, under the argon shield nano-tungsten powder high speed interlayer shear is activated; make pressed compact with the high pressure flexible die forming, in the conventional molybdenum wire furnace, 1500～1550 ℃; be incubated 40～60 minutes, H
2In promptly to can be made into relative density after once sintered be 95～96% superfine crystal particle pure tungsten material (average crystal grain≤8～12 μ m) and goods, concrete technology is:
1, the HTHP supersonic speed hot transformation approach of spraying prepares nanometer WO
3Powder
Adopt the high concentration ammonium tungstate solution, its WO
3Content 350～370g/ liter, with the supersonic speed hot transformation approach of spraying, at aerojet pressure 5～6.5MPa, jet velocity 664～830m/s, under nozzle spray angle α=50 °, 400 ℃ of focal length F=1.51mm hot blast temperatures, adverse current is sent hot blast, liquid stream transporting velocity 400ml/ branch is made nanoscale WO with the high concentration ammonium tungstate solution
3Powder, average grain diameter≤40nm.
2, redox-thinner tungsten powder of reduction prepared sizes repeatedly:
Use H
2(420～500 ℃) 45～60 minutes, in the tubular type reduction furnace with WO
3Be reduced into tungsten powder, its reaction equation is WO
3+ 0.1H
2→ WO
2.9+ 0.1H
2O, was oxidized to anhydrous wolframic acid powder with tungsten powder in 20～35 minutes, its reaction equation: WO by in air 550～650 ℃ then
2.9+ 0.05O
2→ WO
3, and then use H
2(420～500 ℃) 45～60 minutes, in the tubular type reduction furnace with WO
3Be reduced into tungsten powder, reaction equation still is WO
3+ 0.1H
2→ WO
2.9+ 0.1H
2O.More than (redox-reduction) three operations constitute a cyclic process, need carry out three circulations altogether.Finally revert to blue tungsten powder, this process can be the WO of 40nm with average grain diameter
3Powder is reduced into the blue tungsten powder of average grain diameter≤25nm, and its principle is to utilize (WO
3→ WO
2.9) the violent expansion 2 times of a axle during from tungstic acid to blue tungsten deoxidation phase transformation.The C axle expands 6 times, and the b axle shrinks 2 times, and intragranular produces serious detrusion, causes WO
3Particle is broken into thinner WO
2.9Particle is when oxidation, because of WO
2.9→ WO
3Phase transformation, opposite with the reduction phase transformation, WO
2.9It is that a axle shrinks 2 times that a in the crystal grain, c axle sharply shrink, and the c axle shrinks 6 times, and the b axle expands 2 times, and this oxidation phase transformation can cause WO equally
2.9Blue tungsten particle is broken into thinner WO
3Particle, so reduction---oxidation---reduction process repeatedly finally can be made into the granularity WO of average grain diameter≤25nm very uniformly
2.9Powder.
3, blue tungsten particle surface coating furfural alcogel film
Be reduced in the process of tungsten powder at blue tungsten, because the evaporation-condensation of low oxide and the collective recrystallization phenomenon of newborn tungsten powder particles cause the tungsten powder particle-size chap.In order to suppress above-mentioned two kinds of phenomenons, coat thin film with the furfural alcogel on blue tungsten particle surface.This film can play the effect that tungsten powder is isolated below 800 ℃.When temperature is high again.Film can decompose, and residual minim carbon can participate in reaction.In tungsten powder, press blue tungsten: furfural alcoholic solution=100: 5 mass ratioes, add the furfural alcoholic solution, in double-screw type stir mixing machine, mixed 40～60 fens, blue tungsten coated particle is made in 70～80 ℃ of vacuum drying, and the preparation of furfural alcohol liquid is by furfural: phenolic aldehyde: propyl alcohol=2: 1: 10 mol ratios, mix under 70～80 ℃, dissolving is made.
4, the rotary pipe type reduction furnace that seethes with excitement continuously prepares nano-tungsten powder
Reduction furnace seethe with excitement continuously when preparing nano-tungsten powder with rotary pipe type, with the blue tungsten powder of preparation, by boiling boiler tube effective cross-section inlet amount 0.15～0.2 gram/cm continuously
2. divide, at 740～760 ℃, H
2: N
2=3: 2 flow-rate ratios, gaseous mixture total cross section flow 80～100ml/cm
2. divide, tungsten powder is reduced into the tungsten powder of average grain diameter≤70nm continuously, spray into immediately after cooling is come out of the stove that acetone---oleic acid prevents nature, or filling Ar, N
2Slow purification process in the hermetically sealed can.
The rotary pipe type reduction furnace that seethes with excitement continuously is the continuous fluidized bed furnace of a kind of horizontal mechanical swinging, with different at medium-term and long-term ebullated bed or the fluid bed that uses of chemical engineering industry before, the porous plate of this equipment is on the cross sandwich plate that inserts in the pipe of whole reduction furnace garden, in boiler tube, turn round the rule that distributes according to powder, on ad-hoc location, offer the fumarole of different-diameter, no matter being boiler tube, the characteristics of this cross honeycomb sandwich laminate are turned back to what angle, in the bottom of the powder bed of material, the fresh H that sprays can be arranged all from the fumarole of cross porous plate
2And N
2With blue tungsten WO
2.9Powder is winding-up upwards, forms fluidized state, and realize reduction process under the condition of high temperature.Because total reduction furnace tube charging (blue tungsten) end is high, discharging (tungsten powder) end is low, the material of reduction is in the jump process of constantly seething with excitement, move towards discharge end slowly by feed end, in this process, finished by the reduction process of blue tungsten,, solved fluidized bed furnace (fluid bed) so this continuous fluidized bed furnace is easy to realize serialization production to tungsten powder, the air-flow rotary furnace is difficult to realize serialization for a long time, the difficult problem of automated production.
In addition, because the direction that powder particle boiling is beated is vertical with the discharge direction of waste gas in the boiler tube all the time, so the powder particle taken away of working air current, much lower more than the fluid bed fluidized bed furnace, therefore saved a large amount of dedusting reclaimers.Compare with machinery (frid formula) rotary furnace, the powder particle in the fluidized bed furnace has only a kind of line bounce perpendicular to jet plate all the time in reduction process continuously, is isolated by gas phase each other between powder particle, and this movement of particles state helps improving (H
2) the vapour phase reduction reaction speed, be beneficial to and get rid of product steam, prevent that tungsten particle from growing up, but in machinery (frid formula) rotary furnace, because of powder particle except that shedding action, still have the action of roll granulating, the latter grows up to tungsten powder particles and to form the tungsten powder granule very favourable, but very unfavorable concerning preparing nano-tungsten powder.
5, high energy shear activation tungsten powder in the shear breaker between the dry type high-speed layer
Average grain diameter is that the specific surface of the nano-tungsten powder of 70nm is generally 8～13m
2/ g; the sintering activating energy of this powder is very high; but in order further to improve the sintering activating energy of powder; still need the powder particle surface lattice further be distorted with cutter between high-speed layer; for this reason with the nano-tungsten powder of above-mentioned technology 4 preparations between the dry type high-speed layer in the cutter (10000～20000 rev/mins) with argon (Ar) air-flow recycling-guard; after by 60～80 minutes/1kg nano-tungsten powder being carried out high energy shear activation; cooling discharging sprays into acetone immediately---oleic acid liquid or fill Ar, N with hermetically sealed can
2Storage.
6, the high pressure flexible die forming prepares the nano-tungsten powder base
Activation nano-tungsten powder with claim 5 preparation, in the high pressure soft mode, be the power transmission medium with the polyurethane flexible plastic, under 350～450MPa pressure with nano-tungsten powder, be pressed into relative density and be 49～52% pure tungsten pressed compact, the tungsten pressed compact can be carried out machining (deciding on requiring) subsequently.
When soft mode is suppressed, do not need to add any lubricant in the nano-tungsten powder, the high pressure flexible die forming is a kind of technology that is similar to cold isostatic compaction, and its advantage is that forming pressure can surpass isostatic cool pressing, and highest pressure can reach 800MPa.While can be by the vertical decrement of recently controlling powder and the transverse compression amount of soft mode cross-sectional area with dress powder sectional area when flexible die forming.Facts have proved, the nanometer tungsten base of high pressure flexible die forming, density and intensity all are higher than cold isostatic compaction tungsten powder base.
7, (1500～1550 ℃) H in the molybdenum wire furnace
2In once sintered superfine crystal particle pure tungsten material
With the nano-tungsten powder pressed compact of making, in molybdenum wire furnace, 1500～1550 ℃ of H
2Under the atmosphere 45～60 minutes, once sintered, after cooling was come out of the stove, promptly can be made into relative density was 95～96%, pure tungsten material and the goods of mean tungsten crystal grain 8～12 μ m.
The invention has the advantages that:
1, in the process of preparation nano-tungsten powder, adopted highly efficient supersonic atomizer and the rotary pipe type reduction furnace that seethes with excitement continuously, these equipment are can serialization, large-scale production incessantly, the production efficiency height, and the high nano-tungsten powder granularity of producing of automaticity is thinner more even.
2, owing to adopted from WO
2.9-WO
3-WO
2.9Reduction-oxygen-reduction process repeatedly, and in conjunction with furfural alcogel thin film technique, can make the average grain diameter of nano-tungsten powder further refine to≤tungsten powder of 70nm.
3, in the process of preparation pure tungsten material, because the original tungsten powder particle-size≤70nm that adopts, and be the powder that shear breaker is sheared activation processing through between high-speed layer, therefore can reduce the sintering temperature of pure tungsten material effectively, be reduced to 1550 ℃ by 2650 ℃.And can guarantee the very high density of acquisition in the low-temperature primary sintering process, and tiny tungsten grain, this process characteristic has not only been opened up a new technical field again on the technology of preparing of tungsten material, the more important thing is and developed a kind of field with superplasticity tungsten material of ultra-fine grain.
4, the high pressure flexible die forming technology of this patent employing is with solving the problem that it is difficult that nano-tungsten powder is shaped, and not only the production to the large-scale tungsten spare of ultra-fine grain has important use to be worth, and is also significant to solving the difficult problem of other nanometer powders shapings.
Description of drawings
Accompanying drawing 1, be the process chart of this patent.The supersonic speed hot transformation approach of spraying is produced nanometer WO
3Powder 1, redox-reduction preparation nanometer tungsten powder 2 repeatedly, coat furfural alcogel film 3, the rotary pipe type reduction furnace reduction tungsten powder 4 that seethes with excitement continuously, 6, low-temperature sinterings 7 of high speed interlayer shear activation tungsten powder 5 high pressure flexible die formings, examination and test of products packing 8.
The specific embodiment
Embodiment 1: during preparation 10Kg high-density superfine crystal particle pure tungsten material, should follow these steps to finish.
1, the nanometer WO of preparation average grain diameter≤40nm
3Powder
Take by weighing 34.08 liters of high concentration ammonium tungstate solutions, its WO
3Content 370g/ liter, with the supersonic speed hot transformation approach of spraying, at aerojet pressure 6.5MPa, jet velocity 830m/s, under nozzle spray angle α=50 °, 400 ℃ of focal length F=11.5mm hot blast temperatures, adverse current is sent hot blast, liquid flows transporting velocity 400ml/ branch, the high concentration ammonium tungstate solution is made the nanoscale WO of 12.6kg
3Powder, average grain diameter≤40nm.
2, reduction-oxygen-thinner tungsten powder of reduction prepared sizes repeatedly.
Nanometer WO with average grain diameter≤40nm
3Powder in the tubular type reduction furnace 500 ℃, 45 minutes is with nanometer WO
3The powder Restore All becomes WO
2.9Blue tungsten powder, 20 minutes, all is oxidized to nanometer WO with tungsten powder by under tube furnace hollow air-flow 650 ° then
3Powder is put into the tubular type reduction furnace again after coming out of the stove, by 500 ℃, 45 minutes again with the nanometer WO after the oxidation equally
3Powder is reduced into the thinner WO of granularity
2.9Blue tungsten powder has so been finished the cyclic process of first (redox-reduction), finishes the blue tungsten powder that three cyclic processes finally can be made into average grain diameter≤25nm altogether.
3, furfural alcogel film coats tungsten powder:
With 2 tungsten powders of making among the embodiment 1, press blue tungsten powder: furfural alcoholic solution=100: 5 mass ratioes, add the furfural alcoholic solution, in double-screw type stir mixing machine, mixed 60 fens, after 80 ℃ of vacuum drying, to cross 84 μ m sieve and promptly make the tungsten powder that furfural alcogel film coats, the furfural formulations prepared from solutions is by furfural: phenolic aldehyde: propyl alcohol=2: 1: 10, mol ratio is under 70 ℃, and stirring and dissolving is made behind the solution standby.
4, the rotary pipe type reduction furnace that seethes with excitement continuously prepares nano-tungsten powder
With the blue tungsten powder that furfural alcogel film coats, put into diameter phi 200mm, long 4 meters rotary pipe type seethes with excitement in the reduction furnace continuously, and the thorax net sectional area is 150cm in the boiler tube
2, by cross section charging rate 0.15g/cm
2Divide, actual charging rate is 150 * 0.15=22.5g/ branch. at 760 ℃, and H
2: N
2=3: 2 flow-rate ratios, gaseous mixture (H
2+ N
2) total flow (80ml/cm
2. branch * 150cm
2)=12 liter/minute can be reduced into tungsten powder the 10Kg tungsten powder of average grain diameter for≤70nm continuously, spray into acetone-oleic acid solutions immediately after cooling is come out of the stove and prevent spontaneous combustion.
5, the high speed interlayer shear of nano-tungsten powder activation
Under 10000 rev/mins of rotating speeds, Ar argon gas stream recycling-guard by 80 minutes/kg, is sheared activation with nano-tungsten powder with cutter between the dry type high-speed layer, shears the back cooling discharging, sprays into acetone-oleic acid liquid immediately or fills Ar, N with hermetically sealed can
2Store.
6, the high pressure flexible die forming prepares the nano-tungsten powder pressed compact
With 5 among the embodiment 1, the activation nano-tungsten powder of preparation is the power transmission medium with the polyurethane flexible plastic in the high pressure soft mode, under the 450MPa pressing pressure, it is 50% pure tungsten pressed compact 10kg that nano-tungsten powder is pressed into relative density, the tungsten base can be carried out simple machining (deciding on requiring) subsequently.
7, low-temperature primary sintering is made high-density superfine crystal particle pure tungsten material
The nanometer pure tungsten base that among the embodiment 16 made is at 1550 ℃ of molybdenum wire furnaces, H
2Under the atmosphere, 45 minutes, promptly can be made into relative density after once sintered, cooling is come out of the stove was 96%, pure tungsten material or the goods of mean tungsten crystal grain≤8～12 μ m.
1, preparation nanoscale WO
3Powder
Take by weighing 3.41 liters of high concentration ammonium tungstate solutions, its WO
3Content 350g/ liter, with the supersonic speed hot transformation approach of spraying, at aerojet pressure 5MPa, jet velocity 664m/s, under the nozzle spray angle α=50 ° focal length F=11.5mm, 350 ℃ of hot blast temperatures, adverse current is sent hot blast, liquid flows transporting velocity 400ml/ branch, the high concentration ammonium tungstate solution is made the nanoscale WO of 1.26kg
3Powder, average grain diameter≤40nm.
2, reduction---oxygen---reduction prepared sizes thinner tungsten powder repeatedly.
General≤40nm nanometer WO
3Powder in the tubular type reduction furnace 450 ℃, 60 minutes is with nanometer WO
3The powder Restore All becomes WO
2.9Blue tungsten powder, 35 minutes, all is oxidized to nanometer WO with tungsten powder by under tube furnace hollow air-flow 550 ° then
3Powder is put into the tubular type reduction furnace again after coming out of the stove, by 450 ℃, 60 minutes again with the nanometer WO after the oxidation equally
3Powder is reduced into the thinner WO of granularity
2.9Blue tungsten powder has so been finished the cyclic process of first (redox-reduction), finishes the blue tungsten powder that three cyclic processes finally can be made into average grain diameter≤25nm altogether.
3, preparation furfural alcogel film coats blue tungsten powder:
With 2 tungsten powders of making among the embodiment 2, press blue tungsten powder: furfural alcoholic solution=100: 5 mass ratioes, add the furfural alcoholic solution, in double-screw type stir mixing machine, mixed 40 fens, after 70 ℃ of vacuum drying, cross 84 μ m sieve and promptly make the tungsten powder that furfural alcogel film coats.The furfural formulations prepared from solutions is by furfural: phenolic aldehyde: propyl alcohol=2: 1: 10 mol ratios are under 80 ℃, and stirring and dissolving forms.
4, the rotary pipe type reduction furnace that seethes with excitement continuously prepares nano-tungsten powder
With the blue tungsten powder that the furfural alcogel film of 3 among the embodiment 2 preparation coats, put into 4 identical reduction furnaces with embodiment 1, by cross section charging rate 0.2g/cm
2. divide, actual charging rate is 150 * 0.2=30g/ branch. at 740 ℃, and H
2: N
2=3: 2 flow-rate ratios, gaseous mixture (H
2+ N
2) total cross section flow (100ml/cm
2. branch * 150cm
2)=15 liter/minute can be reduced into tungsten powder the 1Kg tungsten powder of average grain diameter for≤70nm continuously, spray into acetone-oleic acid solutions immediately after cooling is come out of the stove and prevent spontaneous combustion.
5, the high speed interlayer shear of nano-tungsten powder activation
Under 20000 rev/mins of rotating speeds, Ar argon gas stream recycling-guard by 60 minutes/kg, is sheared activation with nano-tungsten powder with cutter between the dry type high-speed layer, shears the back cooling discharging, sprays into acetone-oleic acid liquid immediately or fill Ar with hermetically sealed can to store.
6, the high pressure flexible die forming prepares the nano-tungsten powder pressed compact
The nano-tungsten powder that the high speed interlayer shear that among the embodiment 25 prepared activates, in the high pressure soft mode, be the power transmission medium with the polyurethane flexible plastic, under the 350MPa pressing pressure, it is the heavy pure tungsten pressed compact of 49% 1kg that nano-tungsten powder is pressed into relative density, the tungsten base can be carried out simple machining (deciding on requiring) subsequently.
7, low-temperature primary sintering is made high-density superfine crystal particle pure tungsten material
The nanometer pure tungsten pressed compact of 6 among the embodiment 2 preparation just is at 1500 ℃ of molybdenum wire furnaces, H
2Under the atmosphere, 60 minutes, promptly can be made into relative density after once sintered, cooling is come out of the stove was 95%, pure tungsten material or the goods of mean tungsten crystal grain≤8～12 μ m.
Claims (1)
1, a kind of preparation method of low-temperature primary sintering high-density superfine crystal particle pure tungsten material is characterized in that concrete technology:
A, the HTHP supersonic speed hot transformation approach of spraying prepares nanometer WO
3Powder: adopt the high concentration ammonium tungstate solution, its WO
3Content 350～370g/ liter, with the supersonic speed hot transformation approach of spraying, at aerojet pressure 5～6.5MPa, jet velocity 664～830m/s, under nozzle spray angle α=50,400 ℃ of focal length F=11.5mm hot blast temperatures, adverse current is sent hot blast, liquid stream transporting velocity 400ml/ branch is made nanoscale WO with the high concentration ammonium tungstate solution
3Powder, average grain diameter≤40nm;
B, the thinner tungsten powder of reduction-oxidation-reduction prepared sizes repeatedly: use H
2420～500 ℃ of temperature, 45～60 minutes, in the tubular type reduction furnace with WO
3Be reduced into tungsten powder, its reaction equation is WO
3+ 0.1H
2→ WO
2.9+ 0.1H
2O, was oxidized to anhydrous wolframic acid powder with tungsten powder in 20～35 minutes, its reaction equation: WO by in air 550～650 ℃ then
2.9+ 0.050
2→ WO
3, and then use H
2At 420～500 ℃, 45～60 minutes, the tubular type reduction furnace was interior with WO
3Be reduced into tungsten powder, reaction equation still is WO
3+ 0.1H
2→ WO
2.9+ 0.1H
2O; Three operations of reduction-oxidation-reduction constitute a cyclic process, need carry out three circulations; Finally revert to blue tungsten powder, this process can be the WO of 40nm with average grain diameter
3Powder is reduced into the blue tungsten powder of average grain diameter≤25nm;
C, blue tungsten particle surface coat furfural alcogel film: in tungsten powder, press blue tungsten: furfural alcoholic solution=100: 5 mass ratioes, add the furfural alcoholic solution, in double-screw type stir mixing machine, mixed 40～60 fens, blue tungsten coated particle is made in 70～80 ℃ of vacuum drying, the preparation of furfural alcohol liquid, be by furfural: phenolic aldehyde: propyl alcohol=mol ratio mixed under 70～80 ℃ in 2: 1: 10, and dissolving is made;
D, the rotary pipe type reduction furnace that seethes with excitement continuously prepares nano-tungsten powder: seethe with excitement reduction furnace continuously when preparing nano-tungsten powder with rotary pipe type, with the blue tungsten powder of preparation, by boiling boiler tube effective cross-section inlet amount 0.15～0.2 gram/cm continuously
2. divide, at 740～760 ℃, H
2: N
2=3: 2 flow-rate ratios, gaseous mixture total cross section flow 80～100ml/cm
2. divide, tungsten powder is reduced into the tungsten powder of average grain diameter≤70nm continuously, spray into immediately after cooling is come out of the stove that acetone---oleic acid prevents nature, or filling Ar, N
2Slow purification process in the hermetically sealed can;
High energy shear activation tungsten powder in the shear breaker between e, dry type high-speed layer: with the nano-tungsten powder of preparation between the dry type high-speed layer in the cutter 10000～20000 rev/mins use the argon gas stream recycling-guard; after by 60～80 minutes/1kg nano-tungsten powder being sheared activation; cooling discharging sprays into acetone immediately---oleic acid liquid or fill Ar, N with hermetically sealed can
2Storage;
F, high pressure flexible die forming prepare the nano-tungsten powder base: the activation nano-tungsten powder that will prepare, in the high pressure soft mode, be the power transmission medium with the polyurethane flexible plastic, under 350～450MPa pressure with nano-tungsten powder, be pressed into relative density and be 49～52% pure tungsten pressed compact, subsequently the tungsten pressed compact is carried out machining; When soft mode was suppressed, highest pressure can reach 800Mpa;
Once sintered superfine crystal particle pure tungsten material in g, the molybdenum wire furnace: with the nano-tungsten powder pressed compact of making, in molybdenum wire furnace, 1500～1550 ℃ of H
2Under the atmosphere 45～60 minutes, once sintered, after cooling was come out of the stove, making relative density was 95～96%, the pure tungsten material of mean tungsten crystal grain 8～12 μ m.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6368372B1 (en) * | 2000-08-08 | 2002-04-09 | Intrabay Automation, Inc. | Fluid media particle isolating system |
| JP2002371301A (en) * | 2001-06-18 | 2002-12-26 | Allied Material Corp | Tungsten sintered compact and manufacturing method therefor |
| CN1132954C (en) * | 2001-12-13 | 2003-12-31 | 北京科技大学 | Process for preparing W-Cu alloy with superfine crystal grains |
| CN1480282A (en) * | 2003-07-22 | 2004-03-10 | 北京科技大学 | Method for preparing nano superfine tungsten powder |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6368372B1 (en) * | 2000-08-08 | 2002-04-09 | Intrabay Automation, Inc. | Fluid media particle isolating system |
| JP2002371301A (en) * | 2001-06-18 | 2002-12-26 | Allied Material Corp | Tungsten sintered compact and manufacturing method therefor |
| CN1132954C (en) * | 2001-12-13 | 2003-12-31 | 北京科技大学 | Process for preparing W-Cu alloy with superfine crystal grains |
| CN1480282A (en) * | 2003-07-22 | 2004-03-10 | 北京科技大学 | Method for preparing nano superfine tungsten powder |
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