Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
  • H05H1/00—Generating plasma; Handling plasma
  • H05H1/24—Generating plasma
  • H05H1/2406—Generating plasma using dielectric barrier discharges, i.e. with a dielectric interposed between the electrodes
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
  • H05H1/00—Generating plasma; Handling plasma
  • H05H1/24—Generating plasma
  • H05H1/2406—Generating plasma using dielectric barrier discharges, i.e. with a dielectric interposed between the electrodes
  • H05H1/2431—Generating plasma using dielectric barrier discharges, i.e. with a dielectric interposed between the electrodes using cylindrical electrodes, e.g. rotary drums

Definitions

• the invention relates to a method for plasma treatment of a surface of an object, in which a dielectrically impeded gas discharge is generated, and to an apparatus for carrying out such a method.
• a device for plasma treatment is known from DE 10 2006 01 1 312 A1, in which an alternating high voltage is applied to an electrode which has a dielectric shield in order to generate a plasma by means of a dielectrically impeded gas discharge.
• the plasma is generated in a volume adjoining the shield of the electrode, in which a gas which is at atmospheric pressure is arranged, without the apparatus being associated with a counterelectrode.
• a surface of the electrode is provided with tips or needles around which forms a strong electric field due to their small radius of curvature.
• the device can also generate plasma relative to weakly conductive or even insulating objects and without a counterelectrode assigned to the device.
• the device may be designed as a handheld device, which is brought to treat a surface of an object at a suitable distance from the object.
• US Pat. No. 5,711,188 discloses a method and an apparatus for forming a thin layer on a substrate by generating a plasma in a reaction gas and depositing the layer on the substrate.
• the substrate is arranged between an electrode, to which the alternating high voltage for generating the plasma is applied, and a counterelectrode.
• the electrode is spaced from the substrate, with between the electrode and the substrate, a reaction gas is present, in which the plasma is generated.
• the electrode and the counter electrode are mutually adjustable to adjust their spacing to substrates of different thicknesses so that the remaining distance between the surface of the substrate and the electrode over which the plasma is generated remains substantially the same.
• the electrode is rotatably mounted.
• US 2009/009831 1 A1 discloses a method for forming a thin layer by deposition from a plasma, in which an electrical alternating voltage is applied to a rotating cylindrical electrode whose axis of rotation extends parallel to a substrate. The plasma is generated in a space between the rotating electrode and the substrate by applying a voltage in the range of 100 kHz to 1 MHz.
• US 2009/0120782 A1 discloses a device for plasma treatment of the surface of a material web.
• the material web is conveyed via electrically insulated conveyor rollers through a chamber in which the plasma is generated for the treatment of the surface.
• an electrode to which the AC high voltage for generating the plasma is applied as formed by the conveyor rollers rotationally driven solid electrode roller, and the material web is conveyed at a distance from the solid electrode roller through the chamber.
• a roller of electrically conductive material is arranged as a counter electrode.
• the electrode roller is formed on its surface of a porous metal.
• the surface of this porous electrode roller may abut the material web, being flushed with a process gas in which the plasma is formed.
• the electrode and the surface to be treated which is arranged between the electrode and a counterelectrode, must either have a free distance from one another, which is controlled and suitable under given circumstances must be adjusted by the electrode is moved relative to the surface, or that an outer surface of the electrode must be structured so that due to their geometry sufficiently high electric fields are generated for a gas discharge, without a counter electrode is required.
• the invention has for its object to provide a method for a plasma treatment of a surface of an object with the features of the preamble of claim 1 and an apparatus for performing this method, by adjusting the suitable for generating the gas discharge distance between the electrode and the treated surface is simplified and in which a dielectrically impeded gas discharge can be generated without counter electrode, without a complex structuring of the electrode is required.
• the invention relates to a method for plasma treatment of a surface of an object, in which an electrode, which has a convex surface facing the object, is brought closer to the surface of the object to be treated in such a way that at least one plasma region adjoins a contact region between the surfaces is formed in the application of a high alternating voltage to the electrode, a dielectrically impeded gas discharge between the surfaces is generated.
• this method is suitable for producing a dielectrically impeded gas discharge even with respect to insulating or weakly conducting surfaces without the need for a counterelectrode.
• no particular distance between the electrode and the surface to be treated must be maintained, but the electrode is merely brought into contact with the surface, i. H.
• the electrode is approximated with its convex surface to the surface of the object to be treated until the surfaces touch in the contact area. Adjacent to the contact region, due to the convexity of the convex surface of the electrode, regions having different distances between the surfaces of the electrode and the object are formed. It is thereby achieved that in at least one region, which is referred to here as the plasma region, the distance between the surfaces is suitable for generating a dielectrically impeded gas discharge when a high alternating voltage is applied to the electrode. This gas discharge can then produce a plasma in the plasma region.
• the contact region is preferably punctiform or linear.
• punctiform or linear is not to be understood in the strictly mathematical sense, but the punctiform contact region can also be a basically circular contact surface or the linear contact region can be a basically rectangular contact surface.
• Adjacent to the point-shaped contact region the plasma region is then formed as a circular ring space.
• plasma regions with a linear or rectangular projection are formed on the surface. It is understood that both a defined contact region and defined plasma regions are formed only in the case of a smoothly closed convex surface of the electrode. The electrode is therefore solid on its surface, at least not porous.
• the plasma area can be moved relative to the surface of the object.
• the object can be moved relative to a stationary electrode.
• the electrode is moved across the surface of the object.
• surfaces of fixed objects, such as house walls can be treated.
• the electrode may be moved relative to the surface of the object by sliding the electrode with its convex surface over the surface of the object with the convex surface of the electrode sliding over the surface of the object.
• the electrode is rolled over the surface of the object. This can be achieved in a simple manner that the contact area between the surfaces of the electrode and the object moves without the surfaces are damaged by a removal of material or scratching.
• the surface and the diameter of the electrode are adapted so that it can be pushed or rolled over the entire surface of the object without forming a plasma region over a region of the surface to be treated; with the contact area itself, the surface must not be able to be traversed without gaps.
• the surface of the electrode can also be elastically deformable and thus adapted in the contact area to the surface of the object.
• the electrode does not have to be as wide as the object, but can be moved over the object in several tracks next to each other, in order to drive it as a whole.
• the dielectrically impeded gas discharge is preferably generated in a gas which is in the plasma region under atmospheric pressure.
• the Paschen curve ie the plot of the alternating high voltage across the electrode gap required to produce a dielectrically impeded gas discharge multiplied by the gas pressure, has a minimum at a distance of about 10 ⁇ m for a gas at atmospheric pressure.
• This ideal distance is determined by the distance of the surface of the electrode from the upper area of the object, which increases steadily from zero in the contact area, in each case overlined.
• the alternating high voltage which is applied to the electrode can be kept comparatively small, and conversely, when the alternating high voltage is comparatively small, the gas discharge forms exclusively within a defined range around the minimum of the Paschen curve.
• the distance between the surfaces of the electrode and the object in the plasma region is typically between 5 and 20 ⁇ .
• the width and the relative position of the plasma region to the contact region depend inter alia on the curvature of the convex surface of the electrode and the course of the surface of the object.
• the invention further relates to a device for plasma treatment of a surface of an object, which has an electrode with a convex surface and an alternating high voltage source for applying a high AC voltage to the electrode.
• the electrode is approachable with its convex surface to the surface of the object such that adjacent to a contact area between the surfaces forms at least one plasma region in which forms a dielectrically hindered gas discharge between the surfaces when applying the AC high voltage to the electrode.
• electrode In order to generate the dielectric gas discharge, electrode is arranged so that its convex surface touches the surface of the object in the contact area. In adjacent areas, the surfaces are then increasingly spaced from each other, wherein in at least one area, the plasma area, the distance between the surfaces is suitable that when applying the AC voltage to the electrode, the dielectric barrier gas discharge is generated.
• the plasma region typically includes even a larger area than that specified by the distance between the surfaces of the electrode and the object between 5 and 20 ⁇ .
• the AC high voltage required for the dielectric gas discharge is applied to the electrode by the AC high voltage source of the device.
• the alternating high voltage voltage pulses with rise times of not more than 5 s, a pulse duration of less than 10 s and amplitudes of at least 30 kV, wherein the voltage pulses may be bipolar.
• the repetition frequency of the voltage pulses is preferably less than 50 kHz. This limits the power of the gas discharge so that it remains "cold", ie does not rise significantly above room temperature, and of course the power requirements of the device.
• the device according to the invention can have a contact sensor.
• the contact sensor applies a contact formation signal to a controller of the AC high voltage source, and the controller applies the AC high voltage required to generate the dielectric gas discharge to the electrode only when the contact formation signal is present.
• the material of the object whose surface is treatable with the device may be weakly electrically conductive or even insulating.
• the surface of the electrode may be electrically conductive.
• the convex surface of the electrode preferably has a dielectric shield, so that a short circuit in the contact region is prevented.
• the electrode may for example be formed of metal and provided with a silicone sheath. It can also be embodied as a hollow body formed of ceramic, which is filled with a metal powder, or as a glass body filled with a gas, such as a noble gas, in particular helium, with a central metal electrode. In any case, the surface of the electrode which comes to rest against the surface to be treated is closed, i. H. not porous.
• the electrode of the device according to the invention is designed as a rotatably mounted rotary body whose lateral surface forms the convex surface of the electrode.
• the electrode can be designed as a cylinder, which is rotatably mounted about its cylinder axis. This design is particularly for the treatment of largely flat or only in one direction curved surfaces advantageous.
• the contact region is basically linear and on both sides of the line plasma regions are adjacent, in which the dielectric barrier gas discharge is generated.
• the electrode in order to treat a strongly structured surface, such as, for example, a transition between two walls arranged perpendicular to one another, the electrode can, in a further embodiment, be designed as a ball, which is freely rotatably mounted.
• the diameter of the ball can be adapted to the structuring of the surface.
• the surface of the electrode can also be elastically deformable, regardless of its spatial configuration.
• the AC high voltage When the AC high voltage is capacitively coupled to the electrode, the AC high voltage can be easily applied to the electrode without restricting or hindering the rotatable mounting of the electrode.
• the device For the capacitive coupling of the alternating high voltage, the device may have a coupling electrode to which the alternating high voltage is applied.
• the electrode is mounted in a housing made of electrically insulating material.
• the electrode protrudes so far with its convex surface over the housing that the surfaces of the electrode and the object can touch in order to be able to form the contact area and the at least one adjacent contact area.
• rotatable electrodes may protrude 10% to 33% of their diameter from the housing.
• a handle may be provided on the housing so that the device can be carried over the handle and moved over the surface of the object, in particular the electrode can be rolled over the surface of the object. Furthermore, further components, such as the coupling electrode or a mounting for the electrode, may be arranged in the housing.
• the device is designed in a preferred embodiment as a handheld device. In order to supply the device with a high AC voltage, a connectable to a voltage source cable can be provided on the handset. The handset can also be operated with a battery or a rechargeable battery, which is arranged in the handset.
• FIG. 1 shows a cross section of an apparatus according to the invention for the plasma treatment of a surface of an object with a spherical electrode.
• FIG. 2 shows a cross-section of an apparatus according to the invention for the plasma treatment of a surface of an object with a spherical and dielectrically isolated electrode.
• FIG 3 shows a cross-section of a device according to the invention for the plasma treatment of a surface of an object with a cylindrical and dielectrically insulated electrode and an alternating high-voltage contact.
• FIG. 4 shows a cross-section of a device according to the invention for the plasma treatment of a surface of an object with a cylindrical and dielectrically insulated electrode and a coupling electrode.
• the device 1 shows a device 1 according to the invention for carrying out a method for a plasma treatment of a substantially planar surface 2 of an object 3.
• the device has an alternating high voltage source 4 for a high alternating voltage, which is applied to an electrode 6 via a coupling electrode 5.
• the electrode 6 is designed as a freely rotatable ball, which is mounted via a bearing 7, here a ball bearing, in a cup-shaped housing 8 made of an electrically insulating material. In this case, a part of the electrode 6 facing the object 3 projects out of the housing 8.
• a handle 12 is arranged on the housing 8 of the device 1.
• the spherical electrode 6 contacts, with its convex surface 9, the surface 2 of the object 3 in a punctiform contact region 10, and from there the distance between the convex surface 9 of the electrode 6 and the smoothly closed surface 2 of the object 3 increases steadily.
• the contact area 9 adjacent to a plasma region 1 1 is formed, which is a circular space and in which the surfaces of the electrode 6 and the object 3 are spaced apart such that a dielectrically impeded gas discharge in the plasma region 1 1 is generated when the AC high voltage to the Electrode 6 is applied. Since the electrode 6 is freely rotatably mounted as a ball in the housing 8, the electrode 6 can be rolled over the surface 2 of the object 3 and so the plasma region 1 1 are moved over the entire surface 2 away.
• Fig. 2 shows a device 1 according to the invention similar to that shown in Fig. 1, however, the electrode 6 in Fig. 2 on a dielectric shield 13, which surrounds the spherical electrode 6.
• the electrode is formed for example of metal and coated with silicone.
• FIG. 3 shows a further device 1 according to the invention for carrying out a method for a plasma treatment of a substantially planar surface 2 of an object 3.
• the device here has an electrode 6, which is designed as a cylinder rotatable about its cylinder axis.
• the cylindrical surface is provided with a dielectric shield 13, which forms the closed convex surface 9 of the electrode 6.
• the electrode 6 can also be without a dielectric shield 13 if the surface 2 of the object 3 is a material which is only slightly electrically conductive or insulating.
• the electrode 6 is mounted in a cup-shaped housing 8 via a bearing 7, here a stub axle forming bracket.
• a bearing 7, here a stub axle forming bracket In this case, the application of the alternating high voltage via a galvanic contact between the electrode 6 and the electrically conductive bracket or by capacitive coupling via a dielectric away done.
• the bracket made of metal can store a plastic cylinder on which the electrode 6 is arranged in the form of a metal foil with a dielectric shield 13 made of silicone.
• a part of the cylindrical electrode 6 facing the object 3 protrudes from the housing 8 and the electrode touches with its convex surface 9 the surface 2 of the object 3 in a basically line-shaped contact area 10.
• the distance increases between the surfaces 2 and 9 of the Contact area 10 starting on both sides steadily.
• two plasma regions 1 1 Adjacent to the contact region 9, two plasma regions 1 1 are formed, in which the surface 9 of the electrode 6 and the surface 2 of the object 3 are spaced apart such that a dielectrically impeded gas discharge is generated in the plasma regions 11 when the alternating high voltage is applied to the Electrode 6 is applied.
• Fig. 4 shows a device 1 according to the invention similar to that shown in Fig. 3, but the bearing 7, via which the electrode 6 is mounted in the housing 8, executed in Fig. 4 as a bracket made of an electrically insulating material.
• the alternating high voltage is coupled capacitively to the electrode 6 via a coupling electrode 5 here.

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• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Plasma & Fusion (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Physical Or Chemical Processes And Apparatus (AREA)
• Plasma Technology (AREA)
• Treatments Of Macromolecular Shaped Articles (AREA)
• Treatment Of Fiber Materials (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (2)

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Family Applications (1)

Country Status (3)

Cited By (7)

Families Citing this family (3)

Family Cites Families (9)

• 2012
  • 2012-04-20 DE DE102012103470A patent/DE102012103470A1/de not_active Withdrawn
• 2013
  • 2013-04-09 WO PCT/EP2013/057415 patent/WO2013156352A2/fr not_active Ceased
  • 2013-04-09 EP EP13720268.5A patent/EP2839721B1/fr not_active Not-in-force

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