DE102011002183B4 - Apparatus and method for plasma-based production of nanoscale particles and / or for coating surfaces - Google Patents

Abstract

Device for the plasma-assisted production of nanoscale particles and / or for coating surfaces with a process chamber 10, which has electrodes (11, 12, 13) for generating an arc A, B and with at least one gas supply (14) and at least one material supply (15) for generating a gas and material flow C in the process chamber (10), at least one first electrode (11) upstream and at least one second electrode (12) downstream, which have different polarities for generating a first arc A, are arranged at a distance from one another and form a first heating zone (16a) and at least one third electrode (13) with the same polarity as the first electrode (11) is arranged downstream of the second electrode (12) such that between the second and third electrodes (12, 13) a second arc B can be generated and the second and third electrodes (12, 13) a second heating zone (16b) bi lden, characterized in that the ring electrodes each have means (17) for generating a circumferential magnetic field, the means (17) for generating a circumferential magnetic field having at least one magnet (18) and a magnet guide (19) which are in the ring electrode in Circumferential direction are formed, the magnet (18) being movably arranged in the magnet guide (19).

Description

The invention relates to a device for plasma-based production of nanoscale particles and / or for coating surfaces with the features of the preamble of claim 1 and with the features of the preamble of claim 10. The invention further relates to a method for plasma-based production of nanoscale particles and / or for coating surfaces.

A device of the type mentioned is, for example DE 41 05 407 A1 known. Describe similar devices WO 90/15516 A1 and US 4,620,080 A ,

As is known, solid starting materials, for example powders, are liquefied and evaporated in a plasma in order to produce nanoscale particles. Subsequently, the gas phase is rapidly cooled to produce nanoscale particles. The thermal treatment of solid starting materials requires high energies. To transfer the energies, the starting materials should remain in the reactive hot zone for as long as possible. For this purpose, DC plasma systems are used, such as from DE 10 2006 044 906 A1 known. In this system, a plasma torch is used which has a plurality of rod cathodes, which is followed by a pilot anode for igniting the arc. The pilot anode is in turn downstream of a collector anode in the flow direction, which forms a relatively short heating zone together with the rod cathodes. The known arrangement of the collecting anode together with the supply of protective gas causes the solid starting materials are not introduced directly into the plasma, but only strip the plasma at the edge and thus do not affect. The residence time is relatively short for this plasma torch.

The aforementioned DE 41 05 407 A1 discloses a plasma sprayer for spraying solid, powdered or gaseous material. The device is intended to generate a long arc between a cathode arrangement and an annular anode arranged at a distance from the cathode arrangement. The reaction space of this device is nozzle-shaped in order to achieve an energy concentration in the vicinity of the cathode assembly. The structure of this device is complex because of the nozzle-shaped reaction space. In addition, the distance between the cathode assembly and the ring anode is limited.

Other plants for the synthesis of nanoscale powders are out US 2007/0221635 A1 and WO 2005/116650 A2 known.

The object of the invention is to specify a device for the plasma-assisted production of nanoscale particles and / or for the coating of surfaces, which enables efficient evaporation of the starting materials in the heating zone. It is another object of the invention to provide a method for plasma-based production of nanoscale particles and / or for coating surfaces.

According to the invention this object is achieved with regard to the device by the subject-matter of claim 1, alternatively by the subject-matter of the independent claim 10 and with regard to the method by the subject-matter of claim 11.

The invention is based on the idea to provide a device for plasma-assisted production of nanoscale particles and / or for coating surfaces with a process chamber having electrodes for generating an arc and at least one gas supply and at least one material supply for generating a gas and material flow in the process chamber is connected. At least one first electrode is upstream and at least one second electrode is disposed downstream, the electrodes being spaced apart from each other and having different polarities to produce a first arc. The electrodes form a first heating zone.

At least one third electrode having the same polarity as the first electrode is arranged downstream of the second electrode such that a second arc can be generated between the second and third electrodes and the second and third electrodes form a second heating zone.

The invention has the advantage that the efficiency is increased over previously known methods by the alternating arrangement of differently polarizable or polarized electrodes, so that almost any materials can be implemented at higher throughputs. Decisive for this is the enlargement or extension of the thermally effective reaction region and the extended residence times of the starting materials in this zone. On the one hand, this advantage comes into play in connection with the industrial availability of nanoscale particles. On the other hand, this opens up new process windows for other processes, for example for the coating of surfaces. A further advantage of the invention is that the arrangement of the electrodes and the construction of the process chamber is comparatively simple and compact, whereby the production costs are reduced.

A particularly compact embodiment of the device is achieved if at least one rod electrode, in particular a plurality of concentric arranged rod electrodes are provided as first electrodes and ring electrodes as second and third electrodes, wherein at least the ring electrodes are arranged coaxially. Concretely, the first electrode can comprise at least one cathode, in particular a rod cathode, the second electrode an anode, in particular a ring anode, and the third electrode a cathode, in particular a ring cathode. Thus, the sandwich-like or alternating arrangement of the electrodes with different polarities is exemplified.

In a further preferred embodiment, the material supply opens centrally at an axial end of the process chamber in the same such that the material flow in the axial direction can be introduced into the process chamber. Together with the coaxial arrangement of the ring electrodes and the concentrically arranged rod electrodes, an optimization of the residence time is achieved. A further extension of the residence time can be achieved in that the material supply opens in the flow direction in front of the rod electrodes, in particular the rod cathodes in the process chamber, so that the maximum length of the combined heating zones for the implementation of solid starting materials in the process chamber is utilized.

In an advantageous embodiment of the invention, it is provided that the gas supply is integrated in the first electrode, in particular in the rod electrode, whereby a compact construction of the device in the region of the first electrode is achieved.

In the invention, it is provided that the ring electrodes each have means for generating a circulating magnetic field. This prevents the arcs from burning to the ring anode or the ring cathode.

The means for generating a rotating magnetic field has at least one magnet and a magnetic guide formed in the ring electrode in the circumferential direction. The magnet is movably arranged in the magnetic guide. In this way, a magnetic field is generated easily and effectively, which is variable in the circumferential direction of the ring electrode and sufficient to prevent burning of the arcs.

In a particularly preferred embodiment, the magnet is formed spherical or disc-shaped, whereby it is achieved that the magnet can be easily moved in the magnetic guide.

Preferably, the magnetic guide for driving the magnet is connected to a fluid circuit, in particular a water circuit. As a result, in the magnetic guide, a fluid flow can be formed, which entrains the magnet and thus provides for a dynamic change of the magnetic field in the circumferential direction of the ring electrode.

A particularly simple design of the fluid circuit is achieved in that the fluid circuit is integrated into the cooling circuit for cooling the electrode. The already existing cooling circuit for cooling the electrodes of the system thus assumes the drive function for the magnet in the magnetic guide of the ring electrode.

For rapid condensation from the gas phase to transfer the vaporized solids into nanoscale particles, the downstream axial end of the process chamber may be connected to a cooling chamber forming a quench region. Connected to the cooling zone is a cooling gas feed arranged laterally or longitudinally with respect to the longitudinal axis of the process chamber.

Regardless of the electrode arrangement described above, a device for plasma-assisted production of nanoscale particles and / or for coating surfaces with a process chamber is proposed which has electrodes for generating an arc and at least one gas supply and at least one material supply for generating a gas and material flow in the process chamber is connected. At least one first electrode is upstream and at least one second electrode is disposed downstream, the electrodes being spaced apart from each other and having different polarities to produce a first arc. The electrodes form a first heating zone. At least one of the electrodes comprises a ring electrode in which a magnetic guide is formed in the circumferential direction. In the magnetic guide, a magnet for generating a rotating magnetic field is arranged to be movable.

The construction for generating a circulating magnetic field to prevent burning of the arcs at the ring electrode is thus disclosed and claimed both together with the arrangement of the at least three electrodes and independently of this arrangement. This design can be used, for example, with conventional electrode systems where arcing of the arc is to be avoided to increase the efficiency of the system.

According to a further independent aspect, the invention is based on the idea of specifying a device for plasma-assisted production of nanoscale particles and / or for coating surfaces with a process chamber, the electrodes for generating an arc and is connected to at least one gas supply and at least one material supply for generating a gas and material flow in the process chamber. In this case, at least one first electrode upstream and at least one second electrode are arranged downstream of each other spaced apart, which have different polarities for generating a first arc and form a first heating zone. The second electrode includes an anodic portion and a cathodic portion. To produce the first arc with the first electrode, the anodic part forms a common first electrical circuit, which is galvanically isolated from a second electrical circuit. The second electrical circuit includes the cathodic portion and a third electrode disposed downstream of the cathodic portion for generating a second arc. The third electrode forms a second heating zone with the cathodic part.

The invention will be explained and described below with reference to an embodiment shown in the drawing with further details. Show

1 in a schematic representation of a longitudinal section of an embodiment of the invention;

2 a schematic representation of a longitudinal section of another embodiment of the invention with cooling area;

3 an electron micrograph of SiO ₂ nanoscale particles produced by the invention; and

4 a further electron micrograph of SiO ₂ nanoscale particles produced by the invention.

1 shows a longitudinal section schematically a device for plasma-based production of nanoscale article. Nanoscale particles are solids having a mean grain size of about 100 nm or less. It is not excluded that with the help of the device larger particles can be produced. The measurement of the grain size can be done by per se known measuring method based on laser light scattering.

The apparatus comprises means for generating a plasma, specifically a plasma torch, generally designated by the reference numeral 22 is designated. In the plasma torch supplied solid starting materials are melted and evaporated. The condensation of the gaseous phase transferred starting materials takes place in a cooling zone, which in 2 is shown. The cooling zone 20 joins the plasma torch 22 and is connected to it such that the gases generated in the plasma torch in the cooling zone 20 can be transferred and cooled down there quickly. The cooling is carried out in a conventional manner by rapid condensation, so that nanoscale particles are formed.

At the plasma torch 22 it is a DC plasma torch with multiple electrodes. The electrodes 11 . 12 . 13 the plasma burner 22 are in the longitudinal direction of the plasma torch 22 arranged axially one behind the other and form a sandwich-like structure. The sandwich-type structure results from the fact that between two arranged in the axial longitudinal direction upstream and downstream electrodes 11 . 13 the same polarity another electrode 12 is arranged, which has a different polarity. This ensures that the distance between the longitudinal direction of the plasma torch 22 immediately downstream electrodes is relatively low. The total distance that the electrodes 11 . 12 . 13 Cover, however, is comparatively long. As in 1 shown, the total length of the plasma region is composed of several in the longitudinal direction of the plasma torch 22 consecutive arcs A, B together.

Due to the relatively short distance of the electrodes in each case one electrode pair, the formation of the individual light arcs is facilitated. As a result of the combination of the single-sheet sheets A, B, a relatively long process section is formed overall, in which the supplied solid starting materials melt and evaporate. This prolongs the residence time of the starting materials in the hot reaction zone.

The alternating arrangement of differently polarizable or differently polarized electrodes is expandable. Thus, for example, at least 3, at least 4, at least 5 electrodes, etc., may be arranged one behind the other in the gas flow direction, which are alternately polarized differently or polarized differently. Specifically, the third Elektorde at least a fourth electrode with a different polarity, in particular further electrodes with alternating polarities be arranged downstream.

In the embodiment according to 1 the electrode arrangement is realized by the fact that at the first axial end 10a a process chamber 10 , For example, a quartz or ceramic cylinder, first electrodes 11 , in particular several rod cathodes 11 are arranged. For example, two, three, four or more rod cathodes may be provided. Three rod cathodes are preferred 11 , The rod cathodes 11 are concentric with respect to the central axis of the process chamber 10 arranged. The rod cathodes 11 protrude at the first axial end 10a of the process chamber 10 into this. The rod cathodes 11 are also referred to as primary cathodes and can be arranged inclined in a conventional manner with respect to the central axis of the process chamber. The rod cathodes 11 are in a holder 23 , in particular a ceramic holder fastened with a lid 24 the process chamber 10 connected is. The lid 24 closes the first axial end 10a the process chamber 10 gastight and has several bushings for both the rod cathodes 11 as well as for a material feed 15 on.

The material feed 15 is centrally or centrally based on the diameter of the process chamber 10 or the arrangement of the rod cathodes 11 arranged. The material feed 15 comprises a tube whose central axis coincides with the central axis of the process chamber 10 flees. This applies at least to the area of the tube near the lid. The tube of the material supply 15 opens slightly above, ie upstream of the rod cathodes 11 in the process chamber 10 , As a result, the starting materials can be supplied centrically and immediately before the cathodes which are connected upstream in relation to the other electrodes. As a result, an optimization of the residence times of the starting materials in or at least in the vicinity of the plasma torch or the arcs is achieved, whereby the conversion is further improved compared to known methods. The material feed 15 thus forms the center of concentric around the material feed 15 arranged around rod cathodes 11 ,

The rod cathodes 11 have a water cooling 25 which extends substantially in the longitudinal direction of the respective rod electrode 11 extends.

The gas supply 14 is in the embodiment according to 1 into the first electrode 11 , ie integrated into the rod cathode. This is the gas supply 14 with the ceramic holder 23 connected and arranged such that the gas through the lid 24 in the process chamber 10 is directed. The gas flows around the rod cathode 11 and is ionized to generate the plasma in a conventional manner by the arc A. The gas flows around the rod cathodes 11 ,

Alternatively, the gas can also go directly into the process chamber 10 be initiated. For example, the gas supply 14 tangential in the process chamber 10 , in particular in the upper axial end 10a the process chamber 10 lead. By the tangential introduction of the gas into the process chamber 10 is achieved that the gas assumes a preferred flow direction, whereby the process control is stabilized. This applies to all embodiments of the invention.

The rod cathodes 11 is another electrode, in particular a ring anode 12 downstream downstream of the gas flow. As in 1 . 2 to be recognized, between the rod cathodes 11 and the ring anode 12 several arcs 10 clamped. The ring anode 12 has a cooling, in particular a water cooling 26 on. Downstream of the ring anode 12 or the second electrode is a third electrode 13 arranged the same polarity as the first electrode 11 having.

At the third electrode 13 it is thus a cathode, in particular a ring cathode.

In the operation of the system is between the second and the third electrode, ie between the ring anode and the ring cathode 12 . 13 an additional arc B spanned, which significantly extends the entire heating zone. Specifically, the entire heating zone comprises a first heating zone 16a between the rod cathodes 11 and the ring anode 12 and a second heating zone 16b between the ring anode 12 and the ring cathode 13 , The middle ring anode 12 So it works with both the upstream rod cathodes 11 as well as with the downstream arranged cathode 13 together and generates each with the corresponding cathodes one or more arcs.

The downstream ring cathode 13 has similar to the ring anode 12 a cooling, in particular a water cooling 27 on. The water cooling 27 the ring cathode 13 forms a channel, in particular an annular channel, in the region of the upstream axial end of the ring cathode 13 is arranged. The channel of water cooling 27 extends substantially over the entire width of the ring cathode 13 ,

The water cooling 26 the ring anode 12 comprises a double chamber, each forming an annular channel and concentric in the circumferential direction of the annular anode 12 is arranged. The two chambers of water cooling 26 are in the longitudinal direction of the process chamber 10 arranged and through a central cutting disc 28 separated from each other. Through the double chamber of water cooling 26 is achieved that the ring anode 12 both in the area of the arcs A with the rod cathodes 11 as well as in the area of the arc B with the ring cathode 13 is cooled.

Another feature of the device according to 1 is the means 17 for generating a rotating magnetic field at the ring electrodes 12 . 13 , The embodiment of the means described below 17 for generating a rotating magnetic field is associated with both sandwich-type electrode assembly according to 1 . 2 for generating an extended reaction region, as well as independently described and claimed. The configuration described below can therefore also be used independently of the sandwich-type electrode arrangement, that is to say also with ring electrodes known per se in plasma torches within the scope of the invention.

The basic structure of the agent 17 for generating a circulating magnetic field is at the ring anode 12 and the ring cathode 13 similar. In both cases is a magnetic guide 19 provided in the at least one magnet, for example a spherical or a disk-shaped magnet 18 is movably arranged. The drive of the magnet 18 ie the force with which the magnet is 18 in the magnetic guide 19 is moved, is generated hydraulically. This is the magnetic guide 19 connected to a fluid circuit through which in the magnetic guide 19 a fluid flow can be adjusted, which is the magnet 18 takes along and this along the magnetic guide 19 emotional.

The magnetic guide 19 is arranged annularly in the circumferential direction of the annular anode or cathode. By moving the magnet 18 in the magnetic guide 19 a circulating magnetic field is generated which causes a burning of the arcs A and of the arc B at the ring anode 12 or the ring cathode 13 prevented. The fluid circuit can be designed as a separate circuit with its own pump and controller. Alternatively, the fluid circuit for driving the magnet 18 with the cooling circuit of the ring electrodes 12 . 13 be connected. This means that the water cooling 26 . 27 the second and third electrodes 12 . 13 at the same time the magnet 18 in the magnetic guide 19 drives.

The above-described characteristics of the magnetic field generation can be realized for the ring anode and / or the ring cathode.

Specifically, the magnetic guide 19 the ring anode 12 arranged radially outside and forms a channel, in the axial direction of the ring anode 12 is arranged substantially centrally. This means that the channel of the magnetic guide 19 centered on the cutting disc 28 is arranged. Overall, the ring anode 12 essentially symmetrical, in particular rotationally symmetrical. Another arrangement of the magnetic guide 19 , For example, radially further inside, is possible. Due to the symmetrical arrangement of the magnetic guide 19 is achieved that in the magnetic guide 19 arranged magnet 18 equally to the arcs A between the rod cathodes 11 and the ring anode 12 and on the arc B between the ring anode 12 and the ring cathode 13 acts.

The magnetic guide 19 the ring cathode 13 forms a channel which is in the region of the downstream (relative to the gas flow) located Axialendes the ring cathode 13 is arranged. Another arrangement or training of the channel of the magnetic guide 19 is possible.

In the embodiment according to 1 . 2 The fixation of the foot and / or starting points of the arcs is prevented by the rotating magnets. This has the advantage that the heat generated at the wall of the electrodes is dissipated uniformly and low-melting materials, such as copper or brass can be used for the preparation of the electrodes.

As in 2 shown, joins the plasma torch 22 a cooling zone 20 with a cooling gas supply 21 at. The cooling gas supply 21 is in the example according to 2 arranged laterally. Alternatively, the cooling gases can also be supplied axially. The cooling zone 20 is connected in a conventional manner with a collector (not shown).

The device according to 1 works as follows:
In the process chamber is between the first and second differently polarized electrodes, ie between the rod cathodes 11 and the ring anode 12 a first arc A for forming a first heating zone 16a clamped. The first heating zone 16a is through a second heating zone 16b or by combination with a second heating zone 16b extended. For this purpose, a second arc B between the middle second electrodes 16 ie between the ring anode 12 and another third electrode arranged downstream in the direction of gas flow 13 ie the ring cathode 13 clamped. The first and second arcs A, B burn at the same time, so that a total of one of the first and second heating zone A, B combined extended heating zone is formed. In the heating zone is in the field of rod cathodes 11 , specifically immediately before the rod cathodes 11 the solid starting material to be evaporated through a material feed 15 in the process chamber 10 initiated. In addition, on the rod cathodes 11 passing a process gas through the gas supply 14 in the process chamber 10 fed in the area of the first and second heating zone 16a . 16b the plasma forms. In the plasma, the solid starting material is evaporated, both in the first heating zone 16a as well as in the second heating zone 16b which are formed at the same time. The extended overall heating zone prolongs the residence time of the starting materials in the heating zone.

The apparatus described above in connection with the production of nanoscale particles or the method described can be used for the production of thin films by condensation of the gas phase on surfaces.

With the device described above according to 1 . 2 manufactured nano-particles are in the 3 . 4 shown. Such nano-particles or nano-layers are used in the solar industry, microelectronics, environmental technology, in the production of lithium-ion batteries, as sintering additives or as novel fuels.

Not shown in the drawing is a further embodiment of the device according to the invention for plasma-assisted production of nanoscale particles and / or for coating surfaces. The device according to this embodiment, not shown, substantially corresponds to the embodiment according to 1 and differs only in the structure of the process chamber 10 , In particular, it is provided that the process chamber 10 between the electrodes 11 . 12 . 13 is limited by water-cooled, electrically insulated metal cylinder or metal funnel. The upper axial end 10a the process chamber 10 comprises a tapered, double-walled metal tube, electrically insulated from the electrodes by heat-resistant electrical insulators 11 . 12 , in particular the rod cathodes 11 and the ring anode 12 , is separated. The cone-shaped metal tube comprises a cooling water inlet and a cooling water return. Through the cooling water inlet, cooling water flows into the metal pipe, while it flows around the process chamber 10 , in particular the upper axial end 10a the process chamber 10 , and exits through the cooling water return from the metal tube. In this way, the metal tube is cooled. The funnelfrom or the cone-like shape of the metal tube forms a transition from the gas supply 14 the rod cathodes 11 to the circular cylindrical process chamber section passing through the ring electrode 12 is predetermined. In particular, it is provided that the metal tube at a lower end, that of the annular anode 12 facing, having an opening diameter, the opening diameter of the annular anode 12 equivalent. The conical or funnel-shaped, double-walled metal tube essentially delimits the first heating zone 16a in the process chamber 10 ,

The second heating zone 16b in the process chamber 10 is between the ring anode 12 and the ring cathode 13 arranged and bounded by a metal cylinder. The metal cylinder is like the cone-shaped metal tube double-walled and provided with a cooling water inlet and a cooling water return. The metal cylinder has an inner diameter which is substantially equal to the inner diameter of the annular anode 12 or the ring cathode 13 equivalent. At the axial ends of the metal cylinder electrical insulators are arranged, which provide an electrical separation between the metal cylinder and the ring electrodes 12 . 13 accomplish. The cone-shaped metal tube of the first heating zone 16a and the metal cylinder of the second heating zone 16b may include a common cooling water circuit. Alternatively, both for the metal tube, as well as for the metal cylinder each have a separate cooling water circuit can be provided. In addition, it can be provided, the magnetic guides 19 to use as water ducts or as cooling lines, so that the ring electrodes 12 . 13 are coolable. In particular, the magnetic guides 19 be connected to a cooling water inlet and a cooling water return, so that cooling water through the ring electrodes 12 . 13 can flow. An additional line system for cooling the ring electrodes 12 . 13 is avoided in this way. Specifically, the water cooling can 26 . 27 the second electrode 12 and the third electrode 13 and the respective magnetic guides 19 be united in a single component. A cutting disc 28 as with the second electrode 12 or the ring anode 12 is provided, can then be omitted. The cooling of the electrodes 12 . 13 takes place in this case directly by the passage of cooling water through the magnetic guides 19 , The aforementioned applies to all embodiments of the device according to the invention. The cutting disc 28 is therefore optional.

It is possible that the electrically conductive properties of the cone-shaped metal tube and the metal cylinder for additional control of the arcs in the process chamber 10 be used. In particular, a current can be induced in the conical metal tube and / or the metal cylinder from outside, so that the formation of the arcs A, B can be influenced. For this purpose, for example, suitable magnetic coils can be used.

Possible wiring options for the formation of electrical circuits between the individual electrodes 11 . 12 . 13 Foresee that the first electrodes 11 , which are rod-shaped, with the second electrode 12 a common first circuit 40 form, wherein the first electrodes 11 as cathodes and the second electrode 12 are formed as an anode. Furthermore, it is provided in such variants that between the second electrode 12 and the third electrode 13 a second electrical circuit is formed.

A variant provides that the third electrode 13 is formed as a cathode, wherein the second electrode 12 acts as an anode. The second electrode 12 forms an anode for both the first circuit and the second circuit. Preferably, the second electrode 12 is divided into two parts and comprises a first anodic part and a second anodic part, wherein the first anodic part and the second anodic part are galvanically separated from each other. The first anodic part is associated with the first circuit and the second anodic part with the second circuit.

In an alternative variant, however, it is provided that the third electrode 13 forms an anode. Here is the second electrode 12 divided into two parts and includes an anodic part 12a and a cathodic part 12b , The anodic part 12a and the cathodic part 12b are galvanically separated from each other. The anodic part 12a is the first circuit and the cathodic part 12b assigned to the second circuit. In an embodiment in which the electrodes 11 . 12 . 13 are polarized such that in the first circuit, the first electrodes 11 cathodic and the second electrode 12 , especially the anodic part 12a , are connected anodically. In the second circuit, which is galvanically isolated from the first circuit, the second electrode 12 , especially the cathodic part 12b , cathodic and the third electrode 13 be connected anodically.

LIST OF REFERENCE NUMBERS

10

process chamber

10a, 10b

Axial ends of the process chamber

11

first electrode, rod cathode

12

second electrode, ring anode

12a

anodic part

12b

cathodic part

13

third electrode, ring cathode

14

gas supply

15

material supply

16a

first heating zone

16b

second heating zone

17

Means for generating a magnetic field

18

magnet

19

magnetic guide

20

cooling zone

21

Cooling gas supply

22

plasma torch

23

holder

24

cover

25

Water cooling first electrode

26

Water cooling second electrode

27

Water cooling third electrodes

28

cutting wheel

A

first arc

B

second arc

C

material flow

Claims (11)

Device for plasma-based production of nanoscale particles and / or for coating surfaces with a process chamber 10 , the electrodes ( 11 . 12 . 13 ) for generating an arc A, B and having at least one gas supply ( 14 ) and at least one material feeder ( 15 ) for generating a gas and material flow C in the process chamber ( 10 ), at least one first electrode ( 11 ) upstream and at least one second electrode ( 12 ) are arranged spaced apart downstream, which have different polarities for generating a first arc A and a first heating zone ( 16a ) and at least one third electrode ( 13 ) with the same polarity as the first electrode ( 11 ) downstream of the second electrode ( 12 ) is arranged such that between the second and third electrodes ( 12 . 13 ) a second arc B can be generated and the second and third electrodes ( 12 . 13 ) a second heating zone ( 16b ), characterized in that the ring electrodes each comprise means ( 17 ) for generating a circulating magnetic field, wherein the means ( 17 ) for generating a rotating magnetic field at least one magnet ( 18 ) and a magnetic guide ( 19 ) which are formed in the ring electrode in the circumferential direction, wherein the magnet ( 18 ) movable in the magnetic guide ( 19 ) is arranged. Device according to claim 1, characterized in that the first electrode ( 11 ) at least one rod electrode, in particular a plurality of concentrically arranged rod electrodes and the second and third electrodes ( 12 . 13 ) each comprise a ring electrode, wherein at least the ring electrodes are arranged coaxially. Device according to claim 1 or 2, characterized in that the first electrode ( 11 ) at least one cathode, in particular a rod cathode, the second electrode ( 12 ) an anode, in particular a ring anode, and the third electrode ( 13 ) comprise a cathode, in particular a ring cathode. Device according to one of claims 1 to 3, characterized in that the material supply ( 15 ) centrally at a first axial end ( 10a ) of the process chamber ( 10 ) in this opens such that the material flow C in the axial longitudinal direction in the process chamber ( 10 ) can be introduced. Device according to one of claims 1 to 4, characterized in that the gas supply ( 14 ) into the first electrode ( 11 ), in particular integrated in the rod electrode. Device according to one of the preceding claims, characterized in that the magnet ( 18 ) is spherical or disc-shaped. Device according to one of the preceding claims, characterized in that the Leadership ( 19 ) for driving the magnet ( 18 ) is connected to a fluid circuit, in particular a water circuit. Apparatus according to claim 7, characterized in that the fluid circuit is integrated into the cooling circuit for cooling the electrodes. Device according to one of claims 1 to 8, characterized in that the downstream arranged second axial end ( 10b ) of the process chamber ( 10 ) with a cooling zone ( 20 ), which forms a quench area and with respect to the longitudinal axis of the process chamber ( 10 ) lateral or longitudinal axial cooling gas supply ( 21 ) connected is. Device for plasma-assisted production of nanoscale particles and / or for coating surfaces with a process chamber ( 10 ), the electrodes ( 11 . 12 . 13 ) for generating an arc A, B and having at least one gas supply ( 14 ) and at least one material feeder ( 15 ) for generating a gas and material flow C in the process chamber ( 10 ), at least one first electrode ( 11 ) upstream and at least one second electrode ( 12 ) are spaced downstream of each other, which have different polarities for generating an arc A and a heating zone ( 16a ) and at least one of the electrodes ( 11 . 12 . 13 ) comprises a ring electrode in which a magnetic guide ( 19 ) is formed in the circumferential direction, wherein in the magnetic guide ( 19 ) a magnet ( 18 ) is movably arranged to generate a circulating magnetic field, characterized in that the means ( 17 ) for generating a rotating magnetic field at least one magnet ( 18 ) and a magnetic guide ( 19 ) which are formed in the ring electrode in the circumferential direction, wherein the magnet ( 18 ) movable in the magnetic guide ( 19 ) is arranged. Method for operating a device according to any preceding claim, in which in the process chamber ( 10 ) between differently polarized electrodes ( 11 . 12 . 13 ) a first arc A for forming a first heating zone ( 16a ) and the first heating zone ( 16a ) through a second heating zone ( 16b ) formed by generating a second arc B, the first and second arcs A, B burning simultaneously, of the first and second heating zones (FIGS. 16a . 16b ) is supplied to a gas for generating a plasma and material is evaporated in the plasma.

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