CN101920943B - Method and device for preparing single-phase nano epsilon-Fe3N or gamma'-Fe4N powder - Google Patents
Method and device for preparing single-phase nano epsilon-Fe3N or gamma'-Fe4N powder Download PDFInfo
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- CN101920943B CN101920943B CN2010102655029A CN201010265502A CN101920943B CN 101920943 B CN101920943 B CN 101920943B CN 2010102655029 A CN2010102655029 A CN 2010102655029A CN 201010265502 A CN201010265502 A CN 201010265502A CN 101920943 B CN101920943 B CN 101920943B
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Abstract
The invention relates to a method and a device for preparing single-phase nano epsilon-Fe3N or gamma'-Fe4N powder, and the device consists of a plasma evaporation powder making system, a powder collecting and modifying system, a vacuum system and a circulating system. The process steps for preparing the single-phase nano epsilon-Fe3N or gamma'-Fe4N powder are as follows: carrying out vacuum pumping and forced gas circulation, then carrying out plasma evaporation powder making, further carrying out powder modification, controlling the volume flow ratio of ammonia to hydrogen to be (1.4-1.6): 1, controlling the temperature in a powder trapping room at 345-355 DEG C, keeping the temperature for 5-7h, and obtaining the nano single-phase gamma'-Fe4N powder; and controlling the volume flow ratio of the ammonia to the hydrogen to be (2.4-2.6): 1, controlling the temperature in the powder trapping room at 445-455 DEG C, keeping the temperature for 1-3h and obtaining the nano single-phase epsilon-Fe3N powder. The method and the device can ensure that the product is the high-purity single-phase nano iron nitride powder through the precise control of reaction atmosphere.
Description
Technical field
The invention belongs to technical field of magnetic materials, be specifically related to the preparation method and the device of iron nitride material.
Background technology
Nitrided iron mainly comprises Fe
2N, ε-Fe
3N, γ '-Fe
4N and α " Fe
16N
2Deng, they mostly have excellent soft magnetic performance and good corrosion-resistant and oxidation-resistance, are ideal magnetic recording media, magnetic strength element and absorbing material.Such as, γ '-Fe
4The specific saturation magnetization of N phase is 193emu/g, is lower than pure iron (208.5emu/g) slightly.Density is 7.18g/cm
3Be lower than iron and ferrocobalt.Tc is 767K, becomes the metal mold conduction, and the chemicalstability after the passivation is far superior to iron powder.γ ' from magnetic property, density, oxidation resistent susceptibility-Fe
4N is a kind of magnetic recording media, magnetic strength element material and absorbing material of excellence mutually, has special purposes in the high section of electronics, chemical industry and national defence research field.
At present, the method for preparing the nano silicon nitride iron powder body mainly contains following two kinds:
1) nanometer iron powder nitriding.At first nanometer iron powder to be prepared, H can be passed through
2Powder preparing such as reducing hematite, magnetite nanometer pure iron powder.Then, again with the nanometer iron powder body at NH
3-H
2Carry out nitrogenize in the mixed atmosphere, to obtain single component (such as ε-Fe
3N or γ '-Fe
4N is single-phase) or the nitrided iron powder of mixing element (comprise Fe
2N, ε-Fe
3N and γ '-Fe
4N etc.).Because reduction temperature generally about 500 ℃, is easy to cause the reunion of nano-powder and grow up in this temperature, so that nitrided iron product particle diameter, is shaped as needle-like etc. generally greater than 200nm is irregularly shaped.
2) evaporation-condensation method.At N
2Or NH
3-H
2Evaporate pure iron in the mixed atmosphere, form the steam of iron.Iron steam carries out chemical reaction at high temperature and nitrogen containing atmosphere, and the nano silicon nitride iron powder body that can produce mixing element (comprises α-Fe, Fe
2N, ε-Fe
3N and γ '-Fe
4N etc.).This method is difficult to the monophasic nano silicon nitride iron powder body of preparation.
Because preparing method's restriction has particularly ε-Fe of nitrided iron product now on the market
3N and γ '-Fe
4The quality of N is uneven.Along with the fast development of science and technology, in application process to the nitrided iron quality product require increasingly high.So the nitrided iron production technology of exploitation excellent quality is especially developed high purity, colory single phase nano nitrided iron production technology, becomes very important.
Summary of the invention
To present iron nitride material ε-Fe particularly
3N or γ '-Fe
4The weak point that the N material preparation method exists, the present invention provides a kind of preparation single phase nano ε-Fe
3N or γ '-Fe
4The method and apparatus of N powder.
Preparation single phase nano ε-Fe of the present invention
3N or γ '-Fe
4The device of N powder, form by plasma evaporation pulverized coal preparation system, powder collection and reforming system, vacuum system and the recycle system:
The plasma evaporation pulverized coal preparation system constitutes: a reactor drum that has loam cake; Cold-crucible is equipped with in inside; On the reactor enclosure body sidewall, be connected with powder spout and reactor drum inlet pipe; Reactor drum charge flow rate meter is installed on the reactor drum inlet pipe, and arc gum passes loam cake and is fixed together with loam cake, and the electrode of direct-current plasma heating power supply links to each other with the water-cooled crucible with arc gum respectively through cable;
Constituting of powder collection and reforming system: a powder capturing and collecting device with upper end cover, lower end cover, inwall, electric heating body, water jacket and collection blade; The inwall outside is electric heating body and water jacket successively; Powder capturing and collecting device inside is to be provided with the collection blade in the powder dust trapping chamber; The collection blade is fixed together through stiffening web by intra vane and outer leafs and constitutes, and the collection blade pass is crossed coupling shaft and linked together, and is fixed on the upper end cover through coupling shaft.Inlet pipe is passed lower end cover and is communicated with powder dust trapping chamber; Inlet pipe has two arms, and vapor pipe passes upper end cover and is communicated with powder dust trapping chamber, and the end that vapor pipe stretches in the powder dust trapping chamber is equipped with dust filter unit; On the vapor pipe outside powder dust trapping chamber drain tap is installed; First exhaust branch pipe is installed on the vapor pipe at the drain tap upper reaches, and the exhaust branch pipe valve is installed on first exhaust branch pipe, the downstream row tracheae of drain tap is divided into second exhaust branch pipe and the 3rd exhaust branch pipe; Wherein second exhaust branch pipe is communicated with catalytic converter, and the 3rd exhaust branch pipe is communicated with the ammonia dissociation rate survey meter.
Thermopair passes upper end cover and stretches in the powder dust trapping chamber.
First exhaust branch pipe is communicated with inside reactor, and the lower end cover that powder spout passes powder capturing and collecting device is communicated with powder dust trapping chamber; The powder delivery valve is installed on powder spout.
Vacuum system constitutes: on the exhaust branch pipe of exhaust branch pipe valve downstream, be equipped with one and vacuumize arm, vacuumize be installed in series on the arm turbomolecular pump and vacuum pump at this; The operation of vacuum system can obtain condition of high vacuum degree (5.0 * 10 in reactor drum and powder capturing and collecting device
-4Pa), guarantee the production requirement of high purity nitrogenize iron powder.
The recycle system constitutes: variable ratio frequency changer lobe pump and condensing surface have been installed in series on the exhaust branch pipe that vacuumizes the arm downstream.
The operation of the recycle system can realize pump circulation and the cooling through reactor drum, powder spout, powder dust trapping chamber, vapor pipe, exhaust branch pipe, variable ratio frequency changer lobe pump and condensing surface of shielding gas or reactant gases after shielding gas or reactant gases charge into reactor drum.
Inlet pipe in powder collection and the reforming system has two arms, and promptly hydrogen gas lines and ammonia pipeline are respectively arranged with hydrogen flowmeter and ammonia flow meter on two arms.
Adopt the device of the invention described above to prepare single phase nano ε-Fe
3N or γ '-Fe
4The method of N powder is following.Wherein monophasic meaning is a single component.
(1) vacuumize, forced gas circulation
In the water-cooled crucible, pack into behind the pure iron raw material (bulk, purity>=99.99%), close drain tap, open the exhaust branch pipe valve, open the powder spout valve, start vacuum pump and turbomolecular pump successively, reactor drum is evacuated to 1.0 * 10
-4～5.0 * 10
-4Pa.Open reactor drum charge flow rate meter then and charge into shielding gas (Ar) or reactant gases (N
2Or NH
3); Inner gas pressure is 0.01～0.1MPa; Turbomolecular pump is closed in inflation simultaneously, and inflation is closed vacuum pump after accomplishing, and opens the variable ratio frequency changer lobe pump; Realize pump circulation and the cooling of shielding gas through reactor drum, powder spout, powder dust trapping chamber, vapor pipe, exhaust branch pipe, variable ratio frequency changer lobe pump and condensing surface, the circulation velocity scope is 1～5m/s.Recycle gas is through condensing surface, and condensing surface is a shell-and tube condenser, is that 0 ℃ frozen water miscellany is a heat-eliminating medium with temperature, can realize gas cooling to 0～10 ℃.
(2) plasma evaporation powder process
(control voltage 600～900V), ignitor discharge between pure iron negative electrode in the water-cooled crucible and arc gum anode produces plasma high-temperature electric arc (temperature can reach 2000～6000 ℃) to start arc gum.Under the effect of high-temperature electric arc, pure iron melts and evaporates formation iron steam rapidly.Iron steam runs into low temperature (0～10 ℃) shielding gas (Ar) of pump circulation in uphill process, cohesion forms the nanometer iron powder body behind the chilling, perhaps runs into the reactant gases (N of pump circulation
2Or NH
3), and form iron nitride powder with reactant gases chemical combination and (comprise α-Fe, Fe
2N, ε-Fe
3N and γ '-Fe
4N).After powder produces, under the gas of pump circulation drives, get into powder dust trapping chamber, be deposited on the intra vane through powder spout.
(3) powder-modified
After the powder collection reaches predetermined amount; Close arc gum and reactor drum charge flow rate meter; Close the variable ratio frequency changer lobe pump, close exhaust branch pipe valve and powder spout valve, open drain tap; Then in powder dust trapping chamber, feed ammonia and hydrogen, control the flow of two kinds of gases through ammonia flow meter and hydrogen flowmeter respectively.The ultimate constituent of powder determines by capturing room temp, soaking time and atmospheric condition jointly.Control ammonia, hydrogen volume throughput ratio are NH
3: H
2=(1.4～1.6): 1, powder dust trapping chamber temperature is 345～355 ℃, is incubated 5～7 hours, obtains the single-phase γ '-Fe of nanostructure
4The N powder; Perhaps control ammonia, the hydrogen volume throughput ratio is NH
3: H
2=(2.4～2.6): 1, powder dust trapping chamber temperature is 445～455 ℃, is incubated 1～3 hour, obtains the single-phase ε-Fe of nanostructure
3The N powder.In the powder-modified reaction process, ammonia dissociation rate detects through the ammonia dissociation rate survey meter in the stove, and waste gas enters the external world after handling through catalytic converter, and the absorption liquid of catalytic converter is a water.
Confirm the composition (ε-Fe of powder product with X-ray diffraction analysis
3N and γ '-Fe
4N has its characteristic X ray diffracting spectrum line), can demarcate product is purified ε-Fe
3N phase or γ '-Fe
4The N phase is confirmed the diameter of product powder with transmission electron microscope.
The present invention has following characteristics:
1) plasma evaporation pulverized coal preparation system has the vaporization efficiency height, and the fireballing characteristics of powder process are suitable for continuous, batch production requirement;
2) the pump circulation internal gas such as variable ratio frequency changer lobe pump of the big air quantity of employing can be realized the quick cooling of iron steam, can effectively reduce the mean diameter of powder, make its particle size distribution range narrow, and powder dispersity is good, guarantee the quality stability of powder;
3) directly carry out modification after powder is collected and handle, avoided the pollution of foreign matter,, can guarantee that product is high purity, single-phase, nano silicon nitride iron powder body through accurate reaction atmosphere control.
Description of drawings
Fig. 1 is preparation single phase nano ε-Fe of the present invention
3N or γ '-Fe
4The device of N powder constitutes synoptic diagram;
Fig. 2 is the structural representation front view of intra vane and outer leafs;
Fig. 3 is that the A-A of Fig. 2 is to view;
Fig. 4 is the X ray diffracting spectrum of embodiment 1 preparation powder, demarcates to be purified γ '-Fe
4The N phase;
Fig. 5 is the electron scanning micrograph of embodiment 1 preparation powder;
Fig. 6 is the X ray diffracting spectrum of embodiment 4 preparation powders, demarcates to be purified ε-Fe
3The N phase.
Among the figure: 1 direct current plasma heating power supply, 2 cables, 3 arc gums, 4 reactor drums, 5 reactor drum charge flow rate meters, 6 water-cooled crucibles; 7 dust filter units, 8 ammonia flow meters, 9 hydrogen flowmeters, 10 thermopairs, 11 lower end covers, 12 upper end covers; 13 drain taps, 14 exhaust branch pipes, 15 exhaust branch pipe valves, 16 water jackets, 17 electric heating bodies, 18 inwalls; 19 intra vanes, 20 variable ratio frequency changer lobe pumps, 21 powder delivery valves, 22 powder spouts, 23 condensing surfaces, 24 ammonia dissociation rate survey meters; 25 catalytic converters, 26 turbomolecular pumps, 27 vacuum pumps, 28 inlet pipe, 29 vapor pipes, 30 reactor drum inlet pipe; 31 reactor shell, 32 loam cakes, 33 vacuumize arm, 34 outer leafs, 35 coupling shafts, 36 stiffening webs.
Embodiment
Shown in accompanying drawing, apparatus of the present invention are made up of plasma evaporation pulverized coal preparation system, powder collection and reforming system, vacuum system and the recycle system.
The plasma evaporation pulverized coal preparation system constitutes: a reactor drum 4 that has loam cake 32; Cold-crucible 6 is equipped with in inside; On reactor shell 31 sidewalls, be connected with powder spout 22 and reactor drum inlet pipe 30; Reactor drum charge flow rate meter 5 is installed on the reactor drum inlet pipe 30, and arc gum 3 passes loam cake 32 and is fixed together with loam cake 32, and the electrode of direct-current plasma heating power supply 1 links to each other with water-cooled crucible 6 with arc gum 3 respectively through cable 2.
Constituting of powder collection and reforming system a: powder capturing and collecting device that has upper end cover 12, lower end cover 11, inwall 18, electric heating body 17, water jacket 16 and collect blade; Inwall 18 outsides are electric heating body 17 and water jacket 16 successively; Powder capturing and collecting device inside is to be provided with the collection blade in the powder dust trapping chamber; The collection blade is fixed together through stiffening web 36 by intra vane 19 and outer leafs 34 and constitutes; The collection blade pass is crossed coupling shaft 35 and is linked together, and is fixed on the upper end cover 12 through coupling shaft 35.Inlet pipe 28 is passed lower end cover 11 and is communicated with powder dust trapping chamber; Inlet pipe 28 has two arms, and vapor pipe 29 passes upper end cover 12 and is communicated with powder dust trapping chamber, and the end that vapor pipe 29 stretches in the powder dust trapping chamber is equipped with dust filter unit 7; Drain tap 13 is installed on the vapor pipe outside powder dust trapping chamber; Exhaust branch pipe 14 is installed on the vapor pipe at drain tap 13 upper reaches, and on exhaust branch pipe 14, exhaust branch pipe valve 15 is installed, the downstream row tracheae of drain tap 13 is divided into two arms; Be communicated with catalytic converter 25 on one of them arm, another arm is communicated with ammonia dissociation rate survey meter 24.
Thermopair 10 passes upper end cover 12 and stretches in the powder dust trapping chamber.
Vacuum system constitutes: on the exhaust branch pipe in exhaust branch pipe valve 15 downstream, be equipped with one and vacuumize arm 33, vacuumize be installed in series on the arm 33 turbomolecular pump 26 and vacuum pump 27 at this; The operation of vacuum system can obtain condition of high vacuum degree (5.0 * 10 in reactor drum 4 and powder capturing and collecting device
-4Pa), guarantee the production requirement of high purity nitrogenize iron powder.
The recycle system constitutes: variable ratio frequency changer lobe pump 20 and condensing surface 23 have been installed in series on the exhaust branch pipe that vacuumizes arm 33 downstream.Condensing surface 23 is selected shell-and tube condenser commonly used for use.
The operation of the recycle system can realize pump circulation and the cooling through reactor drum, powder spout, powder dust trapping chamber, vapor pipe, exhaust branch pipe, variable ratio frequency changer lobe pump and condensing surface of shielding gas or reactant gases after shielding gas or reactant gases charge into reactor drum.
Inlet pipe in powder collection and the reforming system has two arms, and promptly hydrogen gas lines and ammonia pipeline are respectively arranged with hydrogen flowmeter 9 and ammonia flow meter 8 on two arms.
Each equipment that said apparatus relates to, member (direct current plasma heating power supply 1, arc gum 3, reactor drum charge flow rate meter 5, water-cooled crucible 6, dust filter unit 7, ammonia flow meter 8; Hydrogen flowmeter 9, thermopair 10, drain tap 13, exhaust branch pipe valve 15, water jacket 16, electric heating body 17, variable ratio frequency changer lobe pump 20, powder delivery valve 21, condensing surface 23, ammonia dissociation rate survey meter 24, catalytic converter 25, turbomolecular pump 26 and vacuum pump 27) all to select conventional equipment, member, catalytic converter 25 for use be one to fill the container of water.
Embodiment 1
Preparation single phase nano γ '-Fe
4The method of N powder is following.
(1) vacuumize, forced gas circulation
In the water-cooled crucible, pack into behind the pure iron raw material (bulk, purity>=99.99%), close drain tap, open the exhaust branch pipe valve, open the powder spout valve, start vacuum pump and turbomolecular pump successively, reactor drum is evacuated to 3.0 * 10
-4Pa.Open reactor drum charge flow rate meter then and charge into shielding gas (Ar gas); Inner gas pressure is 0.05MPa; Turbomolecular pump is closed in inflation simultaneously; Inflation is closed vacuum pump after accomplishing, and opens the variable ratio frequency changer lobe pump, realizes pump circulation and the cooling of shielding gas through reactor drum, powder spout, powder dust trapping chamber, vapor pipe, exhaust branch pipe, variable ratio frequency changer lobe pump and condensing surface.Circulation velocity is 3m/s.Recycle gas is through condensing surface, and condensing surface is a shell-and tube condenser, is that 0 ℃ frozen water miscellany is a heat-eliminating medium with temperature, with gas cooling to 5 ℃.
(2) plasma evaporation powder process
Start arc gum, control voltage 750V, ignitor discharge between pure iron negative electrode in the water-cooled crucible and arc gum anode produces the plasma high-temperature electric arc.Under the effect of high-temperature electric arc, pure iron melts and evaporates formation iron steam rapidly.Iron steam runs into low temperature (5 ℃) shielding gas (Ar gas) of pump circulation in uphill process, cohesion forms the nanometer iron powder body behind the chilling; After powder produces; Under the gas of pump circulation drives, get into powder dust trapping chamber through powder spout, be deposited on the intra vane.
The powder productive rate is 80g/h, 5 hours acquisition 400g powders.
(3) powder-modified
After the powder collection reaches predetermined amount (400g); Close arc gum and reactor drum charge flow rate meter; Close the variable ratio frequency changer lobe pump, close exhaust branch pipe valve and powder spout valve, open drain tap; Then in powder dust trapping chamber, feed ammonia and hydrogen, control the flow of two kinds of gases through ammonia flow meter and hydrogen flowmeter respectively.Control ammonia, hydrogen volume throughput ratio are steady state value NH
3: H
2=1.5: 1, powder dust trapping chamber temperature is 350 ℃, is incubated 6 hours, obtains the monophasic γ '-Fe of nanostructure
4The N powder; In the powder-modified reaction process, ammonia dissociation rate detects through the ammonia dissociation rate survey meter in the stove, and waste gas enters the external world after handling through catalytic converter, and the absorption liquid of catalytic converter is a water.
γ '-the Fe of the nanostructure of preparation
4N powder mean diameter 30nm, specific saturation magnetization is 209emu/g, and nitrogen content is 5.9wt.%, and density is 7.20g/cm
3
Embodiment 2
Preparation single phase nano γ '-Fe
4The method of N powder is following.
(1) vacuumize, forced gas circulation
In the water-cooled crucible, pack into behind the pure iron raw material (bulk, purity>=99.99%), close drain tap, open the exhaust branch pipe valve, open the powder spout valve, start vacuum pump and turbomolecular pump successively, reactor drum is evacuated to 5.0 * 10
-4Pa.Open reactor drum charge flow rate meter then and charge into reactant gases (N
2); Inner gas pressure is 0.1MPa; Turbomolecular pump is closed in inflation simultaneously, and inflation is closed vacuum pump after accomplishing, and opens the variable ratio frequency changer lobe pump; Realize pump circulation and the cooling of shielding gas through reactor drum, powder spout, powder dust trapping chamber, vapor pipe, exhaust branch pipe, variable ratio frequency changer lobe pump and condensing surface, the circulation velocity scope is 5m/s.Recycle gas is through condensing surface, and condensing surface is a shell-and tube condenser, is that 0 ℃ frozen water miscellany is a heat-eliminating medium with temperature, can realize gas cooling to 10 ℃.
(2) plasma evaporation powder process
Start arc gum (control voltage 900V), ignitor discharge between pure iron negative electrode in the water-cooled crucible and arc gum anode produces the plasma high-temperature electric arc.Under the effect of high-temperature electric arc, pure iron melts and evaporates formation iron steam rapidly.Iron steam runs into low temperature (10 ℃) reactant gases (N of pump circulation in uphill process
2), and form nitrogenize iron powder art with reactant gases chemical combination and (comprise α-Fe, Fe
2N, ε-Fe
3N and γ '-Fe
4N).After powder produces, under the gas of pump circulation drives, get into powder dust trapping chamber, be deposited on the intra vane through powder spout.
The powder productive rate is 133.3g/h, 6 hours acquisition 800g powders.
(3) powder-modified
After the powder collection reaches predetermined amount (800g); Close arc gum and reactor drum charge flow rate meter; Close the variable ratio frequency changer lobe pump, close exhaust branch pipe valve and powder spout valve, open drain tap; Then in powder dust trapping chamber, feed ammonia and hydrogen, control the flow of two kinds of gases through ammonia flow meter and hydrogen flowmeter respectively.The ultimate constituent of powder determines by capturing room temp, soaking time and atmospheric condition jointly.Control ammonia, hydrogen volume throughput ratio are NH
3: H
2=1.6: 1, powder dust trapping chamber temperature is 355 ℃, is incubated 7 hours, obtains the γ '-Fe of nanostructure
4The N powder; In the powder-modified reaction process, ammonia dissociation rate detects through the ammonia dissociation rate survey meter in the stove, and waste gas enters the external world after handling through catalytic converter, and the absorption liquid of catalytic converter is a water.
γ '-the Fe of the nanostructure of preparation
4N powder mean diameter 32nm, specific saturation magnetization is 208emu/g, and nitrogen content is 5.8wt.%, and density is 7.21g/cm
3
Preparation single phase nano γ '-Fe
4The method of N powder is following.
(1) vacuumize, forced gas circulation
In the water-cooled crucible, pack into behind the pure iron raw material (bulk, purity>=99.99%), close drain tap, open the exhaust branch pipe valve, open the powder spout valve, start vacuum pump and turbomolecular pump successively, reactor drum is evacuated to 1.0 * 10
-4Pa.Open reactor drum charge flow rate meter then and charge into reactant gases (NH
3); Inner gas pressure is 0.01MPa; Turbomolecular pump is closed in inflation simultaneously, and inflation is closed vacuum pump after accomplishing, and opens the variable ratio frequency changer lobe pump; Realize pump circulation and the cooling of shielding gas through reactor drum, powder spout, powder dust trapping chamber, vapor pipe, exhaust branch pipe, variable ratio frequency changer lobe pump and condensing surface, the circulation velocity scope is 1m/s.Recycle gas is through condensing surface, and condensing surface is a shell-and tube condenser, is that 0 ℃ frozen water miscellany is a heat-eliminating medium with temperature, can realize gas cooling to 1 ℃.
(2) plasma evaporation powder process
Start arc gum (control voltage 600V), ignitor discharge between pure iron negative electrode in the water-cooled crucible and arc gum anode produces the plasma high-temperature electric arc.Under the effect of high-temperature electric arc, pure iron melts and evaporates formation iron steam rapidly.Iron steam runs into low temperature (1 ℃) reactant gases (NH of pump circulation in uphill process
3), and form iron nitride powder with reactant gases chemical combination and (comprise α-Fe, Fe
2N, ε-Fe
3N and γ '-Fe
4N).After powder produces, under the gas of pump circulation drives, get into powder dust trapping chamber, be deposited on the intra vane through powder spout.
The powder productive rate is 100g/h, 6 hours acquisition 600g powders.
(3) powder-modified
After the powder collection reaches predetermined amount (600g); Close arc gum and reactor drum charge flow rate meter; Close the variable ratio frequency changer lobe pump, close exhaust branch pipe valve and powder spout valve, open drain tap; Then in powder dust trapping chamber, feed ammonia and hydrogen, control the flow of two kinds of gases through ammonia flow meter and hydrogen flowmeter respectively.Control ammonia, hydrogen volume throughput ratio are NH
3: H
2=1.4: 1, powder dust trapping chamber temperature is 345 ℃, is incubated 5 hours, obtains the single-phase γ '-Fe of nanostructure
4The N powder; In the powder-modified reaction process, ammonia dissociation rate detects through the ammonia dissociation rate survey meter in the stove, and waste gas enters the external world after handling through catalytic converter, and the absorption liquid of catalytic converter is a water.
γ '-the Fe of the nanostructure of preparation
4N powder mean diameter 41nm, specific saturation magnetization is 207emu/g, and nitrogen content is 5.9wt.%, and density is 7.20g/cm
3
Preparation single phase nano ε-Fe
3The method of N powder is following.
(1) vacuumize, forced gas circulation
In the water-cooled crucible, pack into behind the pure iron raw material (bulk, purity>=99.99%), close drain tap, open the exhaust branch pipe valve, open the powder spout valve, start vacuum pump and turbomolecular pump successively, reactor drum is evacuated to 3.0 * 10
-4Pa.Open reactor drum charge flow rate meter then and charge into shielding gas (Ar); Inner gas pressure is 0.05MPa; Turbomolecular pump is closed in inflation simultaneously, and inflation is closed vacuum pump after accomplishing, and opens the variable ratio frequency changer lobe pump; Realize pump circulation and the cooling of shielding gas through reactor drum, powder spout, powder dust trapping chamber, vapor pipe, exhaust branch pipe, variable ratio frequency changer lobe pump and condensing surface, the circulation velocity scope is 3m/s.Recycle gas is through condensing surface, and condensing surface is a shell-and tube condenser, is that 0 ℃ frozen water miscellany is a heat-eliminating medium with temperature, can realize gas cooling to 5 ℃.
(2) plasma evaporation powder process
Start arc gum (control voltage 750V), ignitor discharge between pure iron negative electrode in the water-cooled crucible and arc gum anode produces the plasma high-temperature electric arc.Under the effect of high-temperature electric arc, pure iron melts and evaporates formation iron steam rapidly.Iron steam runs into low temperature (5 ℃) shielding gas (Ar) of pump circulation in uphill process, cohesion forms the nanometer iron powder body behind the chilling.After powder produces, under the gas of pump circulation drives, get into powder dust trapping chamber, be deposited on the intra vane through powder spout.
The powder productive rate is 120g/h, 5 hours acquisition 600g powders.
(3) powder-modified
After the powder collection reaches predetermined amount (600g); Close arc gum and reactor drum charge flow rate meter; Close the variable ratio frequency changer lobe pump, close exhaust branch pipe valve and powder spout valve, open drain tap; Then in powder dust trapping chamber, feed ammonia and hydrogen, control the flow of two kinds of gases through ammonia flow meter and hydrogen flowmeter respectively.The ultimate constituent of powder determines by capturing room temp, soaking time and atmospheric condition jointly.Control ammonia, hydrogen volume throughput ratio are NH
3: H
2=2.5: 1, powder dust trapping chamber temperature is 450 ℃, is incubated 2 hours, obtains the single-phase ε-Fe of nanostructure
3The N powder.In the powder-modified reaction process, ammonia dissociation rate detects through the ammonia dissociation rate survey meter in the stove, and waste gas enters the external world after handling through catalytic converter, and the absorption liquid of catalytic converter is a water.
ε-the Fe of the nanostructure of preparation
3N powder mean diameter 36nm.Specific saturation magnetization is 167emu/g, and nitrogen content is 10.9wt.%, and density is 7.02g/cm
3
Preparation single phase nano ε-Fe
3The method of N powder is following.
(1) vacuumize, forced gas circulation
In the water-cooled crucible, pack into behind the pure iron raw material (bulk, purity>=99.99%), close drain tap, open the exhaust branch pipe valve, open the powder spout valve, start vacuum pump and turbomolecular pump successively, reactor drum is evacuated to 5.0 * 10
-4Pa.Open reactor drum charge flow rate meter then and charge into reactant gases (N
2); Inner gas pressure is 0.1MPa; Turbomolecular pump is closed in inflation simultaneously, and inflation is closed vacuum pump after accomplishing, and opens the variable ratio frequency changer lobe pump; Realize pump circulation and the cooling of shielding gas through reactor drum, powder spout, powder dust trapping chamber, vapor pipe, exhaust branch pipe, variable ratio frequency changer lobe pump and condensing surface, the circulation velocity scope is 5m/s.Recycle gas is through condensing surface, and condensing surface is a shell-and tube condenser, is that 0 ℃ frozen water miscellany is a heat-eliminating medium with temperature, can realize gas cooling to 10 ℃.
(2) plasma evaporation powder process
Start arc gum (control voltage 900V), ignitor discharge between pure iron negative electrode in the water-cooled crucible and arc gum anode produces the plasma high-temperature electric arc.Under the effect of high-temperature electric arc, pure iron melts and evaporates formation iron steam rapidly.Iron steam runs into low temperature (10 ℃) reactant gases (N of pump circulation in uphill process
2), and form iron nitride powder with reactant gases chemical combination and (comprise α-Fe, Fe
2N, ε-Fe
3N and γ '-Fe
4N).After powder produces, under the gas of pump circulation drives, get into powder dust trapping chamber, be deposited on the intra vane through powder spout.
The powder productive rate is 133.3g/h, 6 hours acquisition 800g powders.
(3) powder-modified
After the powder collection reaches predetermined amount (800g); Close arc gum and reactor drum charge flow rate meter; Close the variable ratio frequency changer lobe pump, close exhaust branch pipe valve and powder spout valve, open drain tap; Then in powder dust trapping chamber, feed ammonia and hydrogen, control the flow of two kinds of gases through ammonia flow meter and hydrogen flowmeter respectively.The ultimate constituent of powder determines by capturing room temp, soaking time and atmospheric condition jointly.Control ammonia, hydrogen volume throughput ratio are NH
3: H
2=2.6: 1, powder dust trapping chamber temperature is 455 ℃, is incubated 1 hour, obtains the single-phase ε-Fe of nanostructure
3The N powder.In the powder-modified reaction process, ammonia dissociation rate detects through the ammonia dissociation rate survey meter in the stove, and waste gas enters the external world after handling through catalytic converter, and the absorption liquid of catalytic converter is a water.
ε-the Fe of the nanostructure of preparation
3N powder mean diameter 31nm.Specific saturation magnetization is 167emu/g, and nitrogen content is 10.9wt.%, and density is 7.02g/cm
3
Preparation single phase nano ε-Fe
3The method of N powder is following.
(1) vacuumize, forced gas circulation
In the water-cooled crucible, pack into behind the pure iron raw material (bulk, purity>=99.99%), close drain tap, open the exhaust branch pipe valve, open the powder spout valve, start vacuum pump and turbomolecular pump successively, reactor drum is evacuated to 1.0 * 10
-4Pa.Open reactor drum charge flow rate meter then and charge into reactant gases (NH
3); Inner gas pressure is 0.01MPa; Turbomolecular pump is closed in inflation simultaneously, and inflation is closed vacuum pump after accomplishing, and opens the variable ratio frequency changer lobe pump; Realize pump circulation and the cooling of shielding gas through reactor drum, powder spout, powder dust trapping chamber, vapor pipe, exhaust branch pipe, variable ratio frequency changer lobe pump and condensing surface, the circulation velocity scope is 1m/s.Recycle gas is through condensing surface, and condensing surface is a shell-and tube condenser, is that 0 ℃ frozen water miscellany is a heat-eliminating medium with temperature, can realize gas cooling to 0 ℃.
(2) plasma evaporation powder process
Start arc gum (control voltage 600V), ignitor discharge between pure iron negative electrode in the water-cooled crucible and arc gum anode produces the plasma high-temperature electric arc.Under the effect of high-temperature electric arc, pure iron melts and evaporates formation iron steam rapidly.Iron steam runs into low temperature (0 ℃) reactant gases (NH of pump circulation in uphill process
3), and form iron nitride powder with reactant gases chemical combination and (comprise α-Fe, Fe
2N, ε-Fe
3N and γ '-Fe
4N).After powder produces, under the gas of pump circulation drives, get into powder dust trapping chamber, be deposited on the intra vane through powder spout.
The powder productive rate is 80g/h, 5 hours acquisition 400g powders.
(3) powder-modified
After the powder collection reaches predetermined amount (400g); Close arc gum and reactor drum charge flow rate meter; Close the variable ratio frequency changer lobe pump, close exhaust branch pipe valve and powder spout valve, open drain tap; Then in powder dust trapping chamber, feed ammonia and hydrogen, control the flow of two kinds of gases through ammonia flow meter and hydrogen flowmeter respectively.The ultimate constituent of powder determines by capturing room temp, soaking time and atmospheric condition jointly.Control ammonia, hydrogen volume throughput ratio are NH
3: H
2=2.4: 1, powder dust trapping chamber temperature is 445 ℃, is incubated 3 hours, obtains the single-phase ε-Fe of nanostructure
3The N powder.In the powder-modified reaction process, ammonia dissociation rate detects through the ammonia dissociation rate survey meter in the stove, and waste gas enters the external world after handling through catalytic converter, and the absorption liquid of catalytic converter is a water.
ε-the Fe of the nanostructure of preparation
3N powder mean diameter 35nm.Specific saturation magnetization is 166emu/g, and nitrogen content is 10.8wt.%, and density is 7.03g/cm
3
Claims (5)
1. one kind prepares single phase nano ε-Fe
3N or γ '-Fe
4The device of N powder is characterized in that being made up of plasma evaporation pulverized coal preparation system, powder collection and reforming system, vacuum system and the recycle system:
The plasma evaporation pulverized coal preparation system constitutes: a reactor drum that has loam cake; Cold-crucible is equipped with in inside; On the reactor enclosure body sidewall, be connected with powder spout and reactor drum inlet pipe; Reactor drum charge flow rate meter is installed on the reactor drum inlet pipe, and arc gum passes loam cake and is fixed together with loam cake, and the electrode of direct-current plasma heating power supply links to each other with the water-cooled crucible with arc gum respectively through cable;
Constituting of powder collection and reforming system: a powder capturing and collecting device with upper end cover, lower end cover, inwall, electric heating body, water jacket and collection blade; The inwall outside is electric heating body and water jacket successively; Be provided with the collection blade in the powder dust trapping chamber, inlet pipe is passed lower end cover and is communicated with powder dust trapping chamber, and inlet pipe has two arms; Vapor pipe passes upper end cover and is communicated with powder dust trapping chamber; The end that vapor pipe stretches in the powder dust trapping chamber is equipped with dust filter unit, on the vapor pipe outside powder dust trapping chamber drain tap is installed, and first exhaust branch pipe is installed on the vapor pipe at the drain tap upper reaches; And the exhaust branch pipe valve is installed on first exhaust branch pipe; The downstream row tracheae of drain tap is divided into second exhaust branch pipe and the 3rd exhaust branch pipe, and wherein second exhaust branch pipe is communicated with catalytic converter, and the 3rd exhaust branch pipe is communicated with the ammonia dissociation rate survey meter;
First exhaust branch pipe is communicated with inside reactor, and the lower end cover that powder spout passes powder capturing and collecting device is communicated with powder dust trapping chamber;
Vacuum system constitutes: on the exhaust branch pipe of exhaust branch pipe valve downstream, be equipped with one and vacuumize arm, vacuumize be installed in series on the arm turbomolecular pump and vacuum pump at this;
The recycle system constitutes: variable ratio frequency changer lobe pump and condensing surface have been installed in series on the exhaust branch pipe that vacuumizes the arm downstream.
2. according to the described preparation single phase nano of claim 1 ε-Fe
3N or γ '-Fe
4The device of N powder, it is characterized in that powder is collected and reforming system in the collection blade be fixed together through stiffening web by intra vane and outer leafs and constitute, the collection blade pass is crossed coupling shaft and is linked together, and is fixed on the upper end cover through coupling shaft; Thermopair passes upper end cover and stretches in the powder dust trapping chamber.
3. according to the described preparation single phase nano of claim 1 ε-Fe
3N or γ '-Fe
4The device of N powder is characterized in that the inlet pipe in powder collection and the reforming system has two arms, and promptly hydrogen gas lines and ammonia pipeline are respectively arranged with hydrogen flowmeter and ammonia flow meter on two arms.
4. adopt the described preparation single phase nano of claim 1 ε-Fe
3N or γ '-Fe
4The device of N powder prepares single phase nano ε-Fe
3N or γ '-Fe
4The method of N powder is characterized in that process step is following:
(1) vacuumize, forced gas circulation
In the water-cooled crucible, pack into behind the pure iron raw material, start vacuum pump and turbomolecular pump successively, close drain tap, open the exhaust branch pipe valve, open the powder spout valve, reactor drum is evacuated to 1.0 * 10
-4～5.0 * 10
-4Pa opens reactor drum charge flow rate meter then and charges into argon gas or N
2Or NH
3, inner gas pressure is 0.01～0.1MPa, turbomolecular pump is closed in inflation simultaneously; Inflation is closed vacuum pump after accomplishing, and opens the variable ratio frequency changer lobe pump, realizes pump circulation and the cooling through reactor drum, powder spout, powder dust trapping chamber, vapor pipe, exhaust branch pipe, variable ratio frequency changer lobe pump and condensing surface of shielding gas or reactant gases; The circulation velocity scope is 1～5m/s; Recycle gas is through condensing surface, is that 0 ℃ frozen water miscellany is a heat-eliminating medium with temperature, realizes gas cooling to 0～10 ℃;
(2) plasma evaporation powder process
Start arc gum, control voltage 600～900V, ignitor discharge between pure iron negative electrode in the water-cooled crucible and arc gum anode; Produce the plasma high-temperature electric arc, under the effect of high-temperature electric arc, pure iron melts and evaporates formation iron steam rapidly; Iron steam is in uphill process; Run into 0～10 ℃ argon gas of pump circulation, cohesion forms the nanometer iron powder body behind the chilling, perhaps runs into the N of pump circulation
2Or NH
3, and and N
2Or NH
3Chemical combination forms the nitrided iron powder, after powder produces, under the gas of pump circulation drives, gets into powder dust trapping chamber through powder spout, is deposited to and collects on the blade;
(3) powder-modified
After the powder collection reaches predetermined amount; Close arc gum and reactor drum charge flow rate meter, close the variable ratio frequency changer lobe pump, close exhaust branch pipe valve and powder spout valve; Open drain tap; Then in powder dust trapping chamber, feed ammonia and hydrogen, control the flow of two kinds of gases respectively, control ammonia, the hydrogen volume throughput ratio is NH through ammonia flow meter and hydrogen flowmeter
3: H
2=(1.4～1.6): 1, powder dust trapping chamber temperature is 345～355 ℃, is incubated 5～7 hours, obtains the single-phase γ '-Fe of nanostructure
4The N powder; Perhaps control ammonia, the hydrogen volume throughput ratio is NH
3: H
2=(2.4～2.6): 1, powder dust trapping chamber temperature is 445～455 ℃, is incubated 1～3 hour, obtains the single-phase ε-Fe of nanostructure
3The N powder.
5. according to the described preparation single phase nano of claim 4 ε-Fe
3N or γ '-Fe
4The method of N powder is characterized in that in the powder-modified reaction process, and ammonia dissociation rate detects through the ammonia dissociation rate survey meter in the stove, and waste gas enters the external world after handling through catalytic converter.
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| CN200910013292.1 | 2009-08-21 | ||
| CN2010102655029A CN101920943B (en) | 2009-08-21 | 2010-08-20 | Method and device for preparing single-phase nano epsilon-Fe3N or gamma'-Fe4N powder |
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| CN102378461B (en) * | 2011-09-29 | 2013-02-27 | 北京航空航天大学 | Annular uniform airflow power supplying device |
| CN103072961B (en) * | 2012-10-15 | 2015-05-06 | 宁波广博纳米新材料股份有限公司 | Production method of nano aluminum nitride powder |
| CN103557710B (en) * | 2013-10-28 | 2016-06-15 | 北京泰科诺科技有限公司 | A kind of Rapid Circulation air-cooling vacuum furnace |
| CN105858625B (en) * | 2016-06-26 | 2018-01-30 | 中国计量大学 | One kind nitridation Fe nanowire and preparation method thereof |
| CN108249439A (en) * | 2018-01-02 | 2018-07-06 | 大连理工大学 | A kind of preparation method of transition metal carbide/nitride nano particle and its application in lithium-air battery |
| CN109133103B (en) * | 2018-09-14 | 2021-06-11 | 东南大学 | Chemical-looping ammonia preparation method of iron-based oxygen carrier |
| CN112723326B (en) * | 2020-12-30 | 2022-05-03 | 河北利福光电技术有限公司 | Iron nitride nano powder and preparation method thereof |
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| JPS62102828A (en) * | 1985-10-28 | 1987-05-13 | Daido Steel Co Ltd | Production of fine grain of compound |
| JPH07242404A (en) * | 1994-03-02 | 1995-09-19 | C I Kasei Co Ltd | Production of iron nitride magnetic substance and device therefor |
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| Title |
|---|
| 张成威等.电弧等离子体反应蒸发制备Fe-N纳米粉.《金属功能材料》.1995,(第4-5期),139-141. * |
| 晁月盛等.形成条件对氮化铁(γ′-Fe4N)微观结构及磁性的影响.《功能材料》.2008,第增刊(38)卷960-962. * |
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