WO2002094455A1

WO2002094455A1 - Process for plasma treatment and apparatus

Info

Publication number: WO2002094455A1
Application number: PCT/RU2002/000237
Authority: WO
Inventors: Andrei F. Alexandrov; Gleb E. Bugrov; Konstantin V. Vavilin; Sergei G. Kondranin; Elena A. Kralkina; Vladimir B. Pavlov; Vadim J. Plaksin; Vladimir J. Sergienko; Igor B. Timofeev
Original assignee: Plasma Tech Co., Ltd.
Priority date: 2001-05-18
Filing date: 2002-05-17
Publication date: 2002-11-28
Also published as: RU2196394C1

Abstract

A process for plasma treatment of materials involves supplying of a working gas stream into a discharge gap and igniting a pulsating electric discharge by means of an ignitor electrode (4). An elongated discharge electrode is arranged opposite to the surface to be treated and is preferably formed as a steel string (1). A cyclically variable voltage is supplied to the string (1) for maintaining an extended pulsating discharge under atmospheric pressure. The gas stream is introduced at an angle of 100 to 600 to the longitudinal axis of symmetry of the string (1) and directed toward the surface to be treated. A gas distributing means of the apparatus for treating materials comprises a housing (5) of dielectric material in which inclined gas supply channels (8) are formed. Outlet openings of inclined channels (8) are uniformly distributed over the surface of the housing (5) and arranged opposite to the string (1) lengthwise thereof. The invention permits modification of the surface properties of the material to be treated to a high level of uniformity.

Description

PROCESS FORPLASMA TREATMENT AND APPARATUS

Field of the Invention

The invention relates to a plasma technique and to a procedure for plasma treatment of materials, more particularly, it pertains to the processes for treating article surfaces by means of high-pressure gas discharges for modifying the material surface energy: to increase the water absorbing or water repelling capacity of the surface to be treated, as well as to improve the adhesion and corrosion resistance.

Prior Art

Various processes and means for treating the materials in a corona discharge plasma under atmospheric pressure are of considerable current use.

As an example, US Pat. 5,895,558 (IPC H05F3/00, published 20.04.1999) discloses an apparatus and a process for treating a polymer film in an electric discharge plasma under atmospheric pressure. The known apparatus is comprised of cooled electrodes arranged one opposite to another and adapted to be connected to a high-frequency voltage source. The frequency magnitude of a pulsating voltage is from 1 to 30 MHz. The lower electrode is separated from a discharge gap by a barrier dielectric layer. During treatment of the material, the discharge space is filled with a working gas under atmospheric pressure through openings formed in end parts of the electrodes. The working gas stream is supplied at right angles to the surface of the material to be treated to define a turbulence zone inside the discharge gap. After igniting a discharge between the electrodes, the discharge gap between a cathode and the barrier dielectric layer arranged above the surface of an anode is filled with a high-frequency discharge plasma. The polymer material is treated by exposing it to the radiation emitted by electrons and negative ions generated in the discharge plasma, as well as by the ultraviolet radiation emitted from the discharge plasma. Such process of treating the polymer material is carried out at a low temperature, i.e. at the temperature of a glow discharge plasma, to eliminate the possibility of destroying the material. US Pat. 5,403,453 (IPC H05F3/00, published 04.04.1995) describes another process of treating the material (film, woven or non-woven fabric) in the plasma of a glow pulsating discharge under atmospheric pressure of the working gas. Such process and an apparatus for carrying out the process are used to impart the required properties, such as wettability (the water absorbing or water repelling capacity) and porosity, to the material to be treated. The apparatus is composed of discharge electrodes arranged one opposite to another and a metal perforated grounded electrode arranged in a discharge space between the discharge electrodes. The working surfaces of the discharge electrodes and of the grounded electrode are coated with a barrier dielectric layer. Plasma generation inside the working space takes place upon delivering of a supply voltage at a frequency of from 1 to 100 kHz from a high-frequency voltage source and upon ignition of a pulsating electric discharge between the discharge electrodes. The material (fabric) to be treated is moved through a plasma generation zone between one of the discharge electrodes and the perforated grounded electrode. During passage of the material through the discharge space, the material surface is irradiated with charged particles and the material properties are thereby modified.

In the process of treatment, the working gas is supplied in a forced circulation mode along the surface of the fabric passing through the discharge space. The controlled supplying of the working gas and the optimized power frequency range provided by means of the above apparatus allow the pulsating discharge to be partially stabilized in the discharge space so as to generate plasma along the entire surface of the fabric to be treated.

In another apparatus described in US Pat. 5,215,636 (IPC H01J 19/08, published 01.06.1993), discharge electrodes are arranged along the surface to be treated, with a heavy grounded electrode being disposed beneath the surface to be treated. Materials are treated in the process of conveyance of an elongated tape or tube through the discharge space, where plasma is generated after ignition of a pulsating discharge at a frequency of about 500 kHz. Improved wettability and adhesion of the surface to be treated are achieved by exposing the surface to an intensive ultraviolet radiation or to any other electromagnetic radiation, as well as by subjecting the surface to electronic, ionic and radical bombardment from the discharge space. Stabilization of the electric discharge along the entire surface of the material to be treated, according to the embodiment of the known process, is enabled by uniform distribution of the working gas stream over the entire surface to be treated. A gas distribution means may be arranged in such apparatus immediately above the surface to be treated, between the discharge electrodes. Outlet channels of the gas distributing means are oriented at right angles to the surface to be treated and, respectively, to the surface of the grounded electrode arranged below the ribbon of dielectric material to be treated. The pulsating electric discharge is ignited along the surface to be treated.

Analogs (prototypes) most closely related to the patentable process for plasma treatment of materials, plasma generation process and apparatus are the corresponding processes and an apparatus described in US Pat. 5,026,463 (IPC B05D 3/14, published 25.06.1991). The apparatus for treating a thin ribbon material in a pulsating corona discharge plasma under atmospheric pressure includes at least one elongated discharge electrode arranged above the material surface to be treated and commensurable with the ribbon width. A heavy grounded body equipped with a barrier dielectric layer is arranged below the ribbon or sample of material to be treated. Such body may be, for example, a metal drum equipped with dielectric coat and designed for ribbon winding.

A voltage with a magnitude of 20 to 70 kV is supplied to the discharge electrode at a frequency of 20 to 25 kHz. As a result, a pulsating corona discharge is ignited within the working gas medium. The working gas is supplied by means of a specially designed gas distributing means, which is communicated to a gas supply system. Outlet channels of the gas distributing means are directed at right angles to the surface to be treated and perpendicular to core-type discharge electrodes. Such embodiment of the gas distributing means permits the uniform distribution of working gas over the length of the discharge electrodes and, accordingly, over the entire width of the ribbon to be treated, which, combined with the chosen optimal electric parameters, permits maintaining of uniform distribution of the pulsating corona discharge over the entire surface of the material to be treated. Alteration of material properties is carried out by combined exposure of the surface to be treated to radiation with charged particles and chemical modification by subjecting the surface to the action of functionally active groups and radicals, which is performed by supplying chemically reactive gases through the gas distributing means. As a result of action upon the basic material, the latter is polymerized and the polymer crosslinking density is increased.

However, employment of the above process for plasma generation, process for plasma treatment and apparatus for treating the materials does not provide for high level uniformity of plasma density over the width of the surface to be treated and stability of the pulsating discharge under atmospheric pressure. The probability of localization of the corona discharge above a part of the ribbon to be treated is sufficiently high yet. The mentioned phenomenon, in its turn, results in non-uniform properties of the material, i.e., the occurrence of surface imperfections. Besides, the embodiment of the known process implies maintaining the supply voltage and its frequency within sufficiently narrow bands providing for smooth burning of the pulsating discharge. Disclosure of the Invention

The basis for the patentable group of inventions, which are interrelated so that define a single inventive idea, is the development of an extended pulsating discharge under atmospheric pressure of a working medium and within a wide range of operating frequencies, which has increased stability and uniformity along a discharge electrode. Implementation of such object permits modification of properties of the material to be treated with an increased extent of uniformity over the entire surface both at variable composition of the working gas and variable discharge parameters. The mentioned advantage provides for increased quality of material treatment and wider operational capabilities for altering the properties of the material in the process of continuous industrial production.

This object is achieved by employing the process of plasma treatment of materials under atmospheric pressure, which involves supplying working gas stream into a discharge gap from the side of a discharge electrode under external atmospheric pressure, striking a pulsating electric discharge by means of at least one elongated electrode arranged opposite to the surface to be treated, supplying a cyclically variable voltage to the elongated electrode, and maintaining an extended pulsating discharge under atmospheric pressure for plasma generation in the process of the material treatment. According to the present invention, plasma generation is carried out by supplying the working gas stream at an angle of 10 to 60 to the axis or plane of symmetry of the elongated electrode. The gas stream is uniformly supplied along the elongated electrode toward the surface to be treated. The elongated discharge electrode may be formed as a metal core or, preferably, as a metal string. In this case, the gas stream is directed at an angle to the axis of symmetry of the electrode. In case the elongated electrode is formed as, for example, a metal tape, the gas stream is supplied at an angle to the plane of symmetry of the electrode. The working gas stream is created and blown through a discharge space at the predetermined ratio of longitudinal and transverse stream velocity components relative to the surface of the elongated discharge electrode to facilitate formation of a spatially homogenous micro discharge region of plasma, which is generated over the entire length of the elongated discharge electrode. Such spatially homogeneous stable plasma formation extending transverse to the ribbon of material conveyed through the discharge space provides for uniform action upon the surface to be treated and, as a consequence, high-quality treatment of the material.

The pulsating electric discharge is preferably ignited by means of at least one ignitor electrode to which a pulsating voltage is supplied. The pulsating electric discharge under atmospheric pressure may be ignited between the elongated discharge electrode and a grounded electrode arranged below a substrate of the dielectric material to be treated. The pulsating electric discharge may be ignited and maintained without employment of the additional grounded electrode.

The above object is also achieved by a process of plasma generation under atmospheric pressure, which involves supplying of the working gas stream into the discharge gap from the side of the discharge electrode, igniting a pulsating electric discharge by means of at least one elongated discharge electrode to which a cyclically variable voltage is supplied, and maintaining the extended pulsating discharge under atmospheric pressure. According to the present invention, plasma generation is effected by supplying the gas stream at an angle of 10 to 60° to the axis or plane of symmetry of the elongated electrode, with gas flow being uniformly supplied along the surface of the elongated discharge electrode.

The elongated discharge electrode may be formed as a metal core or, preferably, as a metal string. In this case, the gas stream is supplied at an angle to the axis of symmetry of the electrode. If the elongated discharge electrode is formed, for example, as a metal tape, the gas stream is supplied at an angle to the plane of symmetry of the electrode.

The object is also achieved by means of an apparatus for plasma treatment of materials under atmospheric pressure, comprising at least one elongated discharge electrode with terminals for connecting to a power supply source, a gas distributing means for blowing a working gas stream through the elongated discharge electrode arranged opposite to the surface to be treated, and a system for moving the material to be treated into a discharge space. According to the present invention, the gas distributing means comprises a dielectric housing with inclined gas supply channels whose outlet openings are arranged opposite to the discharge electrode surface. The inclined channels are oriented at an angle of 10° to 60° to a longitudinal axis or plane of symmetry of the elongated discharge electrode, toward the surface to be treated, and are uniformly distributed over the surface of the gas distributing means housing, along the elongated discharge electrode.

The inclined gas supply channels are preferably formed as Laval nozzles. Such embodiment permits an increase in the transverse dimension of a spatially homogeneous plasma zone above the surface to be treated owing to an increased distance of directed supplying of the working gas. To facilitate the ignition of a spatially extended pulsating discharge and simplify the power supply system, the apparatus comprises at least one ignitor electrode arranged in the vicinity of the elongated discharge electrode.

The apparatus may include a system for feeding the material formed as ribbon, which is passed through the discharge space by means of winding drums. If the ribbon-shaped material is to be treated, an additional treatment, such as radiation of the ribbon surface by means of an ultraviolet source, and/or blowing of the ribbon by chemically reactive gas, may be effected simultaneously with passage of the material. The radiation source and the gas supply system are arranged above the movable ribbon. In the case of treatment of a flat substrate made of the material to be treated, the system for feeding the material to be treated into the discharge space may be equipped with at least one unit for reciprocating the substrate relative to the elongated discharge electrode.

The elongated discharge electrode may be formed as a metal core. A preferred embodiment has the elongated discharge electrode formed as a metal string equipped with an extension spring. The elongated discharge electrode may be further formed as a metal tape. In the latter case, the inclined channels are oriented at an angle of 10° to 60° to the longitudinal plane of symmetry of the tape-shaped discharge electrode.

The spatial homogeneity of the micro discharge plasma may be improved by using at least one grounded metal electrode and arranging it below the substrate or ribbon of material to be treated. Such embodiment implies ignition of the extended discharge between one or several discharge electrodes and the grounded electrode.

Brief Description of the Drawings

The group of patentable inventions are explained by a detailed description of concrete examples of embodiment with reference to the applied drawings including:

Fig. 1 shows a schematic view of a longitudinal section of a gas distributing means with an elongated discharge electrode and an ignitor electrode;

Fig. 2 shows a schematic view of a longitudinal section of a gas distributing means with an elongated discharge electrode and seven ignitor electrodes;

Fig. 3 shows a schematic view of an apparatus for plasma treatment of materials equipped with substrate reciprocating unit;

Fig. 4 shows a schematic view of an apparatus for plasma treatment of materials equipped with a system for feeding a ribbon through a discharge space; Fig. 5 shows a graphic representation of the dependence of a limiting (wetting) angle θ (in degrees) of a stainless steel sample on time T (in days) after plasma treatment of the material according to the invention;

Fig. 6 shows a graphic representation of the dependence of a limiting (wetting) angle θ (in degrees) of a carbon steel sample on time T (in days) after plasma treatment of the material according to the invention;

Fig. 7 shows a graphic representation of the dependence of a limiting (wetting) angle θ (in degrees) of an aluminum sample on time T (in days) after plasma treatment of the material according to the invention; Fig. 8 shows a graphic representation of the dependence of a limiting (wetting) angle θ

(in degrees) of a polyethylene sample on time T (in days) after plasma treatment of the material according to the invention;

Fig. 9 shows a graphic representation of the dependence of a limiting (wetting) angle θ (in degrees) of a polyimide sample on time T (in days) after plasma treatment of the material according to the invention;

Fig. 10 shows a graphic representation of the dependence of a limiting (wetting) angle θ (in degrees) of a vinyl chloride sample on time T (in days) after plasma treatment of the material according to the invention.

Preferable Examples of Embodiment of the Invention

An apparatus for plasma treatment of materials under atmospheric pressure illustrated in Figs 1 to 4, is comprised of several plasma generating modules. Each plasma generating module includes an elongated discharge electrode formed as a steel string 1 stretched by means of a tension spring (not shown in a drawing) between terminals 2 and 3 designed for connection to a power supply system. It should be noted that manufacture of the discharge electrode as the string is by no means the only embodiment possible, other versions, such as a core or a metal tape, are also possible. A pointed ignitor electrode 4 is fixed on the string 1. In a preferred embodiment of the apparatus (see Fig. 2), seven pointed ignitor electrodes are arranged in equally spaced relation along the string 1. Such embodiment allows the discharge to be ignited along the entire surface of the string 1. Each discharge module is comprised of a gas distributing means having a dielectric housing 5 within which is arranged a gas distributing chamber 6 with an inlet opening 7 and inclined channels 8, with outlet openings of said channels being arranged in equally spaced relation in a row opposite to the string 1. Inclined channels 8 are oriented at an angle of 50 to the longitudinal axis of symmetry of the string 1 toward the surface to be treated. Figs 1 and 2 illustrate the inclined channels 8 formed as cylindrical channels, though shaped channels, in particular, Laval nozzle-shaped channels, may be used for gas supplying. In deciding on one or other shape of the inclined channels 8, a number of factors defining the gas-dynamic distribution of the working gas stream along the surface of the discharge electrode (string 1 ) and the requirements imposed upon the apparatus manufacture process should be taken into account.

The apparatus for plasma treatment of materials is further comprised of a system for feeding the material to be treated into the discharge space. In the case of plasma treatment of flat substrates (see Fig. 3), such system includes units 9 for reciprocating substrates 10 manufactured of the material to be treated. Three rows of discharge units 11 are arranged in mutually overlapping relation across the whole width of the substrate 10 above the substrate passage zone. Each discharge unit 11 is comprised of a gas distributing means and an elongated discharge electrode.

In the case of plasma treatment of a material formed as a ribbon 12 (see Fig. 4), the system for feeding the material to be treated includes winding drums 13 for moving the ribbon 12 through the discharge space. Three rows of discharge units 11 are arranged in a mutually ovelapping relation above the ribbon manufactured of the material to be treated across the width of the ribbon 12. Besides, an ultrviolet radiation source 14 is arranged upstream of the rows of discharge units 1 1 , and a system 15 for additional treatment of the ribbon 12 in a reactive gas medium is positioned downstream of the rows of discharge units 11 in the transport direction of the ribbon 12. The system 15 may be made in the form of a gas distributing means for uniform supplying of a reactive gas or mixture thereof across the width of the ribbon 12.

The apparatus may also include grounded metal electrodes arranged below the substrate or the ribbon of material to be treated (not shown in a drawing). The grounded electrodes are shielded from the discharge space by a barrier dielectric layer, which may be the material to be treated, provided that it has sufficiently high permittivity. The grounded electrodes may be, for example, the winding drums 13.

Operation of the above apparatus and the corresponding process for plasma treatment of materials under atmospheric pressure are carried out in the following manner.

Plasma is generated in each of the discharge units mounted above the substrate or ribbon manufactured of the material to be treated, according to the sequence of procedures claimed by the plasma generation process. Plasma is generated under atmospheric pressure of the working gas medium. The working gas is introduced under excessive pressure into the inlet opening 7 of the housing 5 of the gas distributing means. The working gas is the mixture of air, argon, nitrogen and oxygen. The gas stream is uniformly distributed over the whole volume of the chamber 6 of the gas distributing means, and the gas is delivered under equal pressure into each of a number of inclined channels 8. The inclined channels 8 whose outlet openings are arranged opposite to the string 1 , provide for supplying of the working gas over a generatrix surface of the inclined channels, i.e., at an angle of 50° to the longitudinal axis of symmetry of the string 1 , toward the surface to be treated.

Thereafter, the operating voltage of about 3 kV at a frequency of 13.56 MHz is supplied to the terminals 2 and 3 with the string 1 stretched between them. The ignition of a discharge is initiated by means of a pointed ignitor electrode connected to the string 1 (see Fig.l). In case of usage of a rather long string 1 , the ignition of discharge is effected by means of a set of ignitor electrodes 4, which are arranged in equally spaced relation along the string 1 (see Fig. 2). The discharge parameters may be optimized in accordance with the concrete technological object.

Investigations have shown that the longitudinal and transverse gas stream velocity component ratio at the surface of an electrode is of essential importance for producing an extended pulsating electric discharge, which represents a spatially homogeneous distribution of micro discharges (streamers) over an elongated discharge electrode. The longitudinal and transverse component ratio of gas stream velocity is established in accordance with an inclination angle of channels 8 to the longitudinal axis of symmetry of the string 1.

The working gas stream must be introduced at an angle of 10° to 60° to the axis of symmetry of the string 1 toward the surface to be treated. At angles less than 10 , the discharge was essentially non-homogeneous. At angles larger than 60°, the ignition of a spatially homogeneous pulsating electric discharge over the entire length of a discharge electrode had failed. A smooth homogeneous burning of a pulsating extended electric discharge was possible in the restricted range of working gas supply directions, defined by the range of channel inclination angles of 10 to 60°. The mentioned ratio of the gas stream velocity components allows predetermined requirements of a pulsating discharge stability and micro discharge plasma spatial homogeneity to be satisfied within a wide range of working gas flow rates and the power supplied. The working gases may be both inactive and reactive gases, as well as vapors of various substances and gases forming chemical radicals.

The described process for plasma generation is characteristic of all discharge units 11 used for plasma treatment of materials as part of a corresponding apparatus (see Figs 3 and 4). During operation of the apparatus, electric power is uniformly supplied to each discharge unit 11 through conventional radio technical means. After igniting of an extended pulsating discharges in the discharge units 11 which are arranged in three rows transverse to the substrate 10 to be treated ( see Fig. 3), the substrate 10 is reciprocated by means of reciprocating units 9. Such reciprocating motion of the substrate 10 is performed in order to provide for uniform treatment of the entire surface during multiple travels thereof below the rows of discharge units 11. The spatially uniform distribution of plasma generated is carried out by means of grounded electrodes, which may be the units 9 for reciprocating the substrate 10. The units 9 are isolated from the discharge space by a barrier dielectric layer. Regarding the mentioned system for feeding materials, which is equipped with the units 9 for reciprocating the substrate 10 through the discharge space, it is best suited for treating flat substrates having dimensions exceeding the dimensions of the region accommodating the discharge units 11.

If ribbon 12 is used as the material to be treated, an arrangement comprising winding drums 13 for passing the ribbon made of the material to be treated through the discharge space at a predetermined velocity (see Fig. 4) is employed. Such embodiment of the apparatus allows additional procedures for treating the ribbon 12 to be effectuated along with plasma treatment in an extended pulsating discharge. The ribbon surface to be treated is preliminarily exposed to radiation from the ultraviolet radiation source 14. Exposure of the material to be treated to the ultraviolet radiation causes the surface layer to be preliminarily activated. Thereafter the surface to be treated of the movable ribbon 12 is introduced into the discharge space region composed in a row of spatially homogeneous plasma generated by means of the discharge units 1 1. According to the invention, a spatially homogeneous extended pulsating electric discharge of a required burning stability is generated in each of the discharge units 11. It results in that a spatially extended homogeneous plasma is formed in the discharge space to serve as a source of electrons, ions and chemical radicals providing for uniform radiation of the surface to be treated. Uniform distribution of plasma within the discharge space is enhanced through the usage of grounded electrodes, which are isolated from the discharge space by a barrier dielectric layer. Such electrodes in the example of embodiment under consideration are the winding drums 13 arranged below the ribbon 12. By this expedient the discharge units 11 in each row of units 11 perform successive and uniform surface treatment under atmospheric pressure. Upon completing of the plasma treatment process, the ribbon 12 is passed above the zone where an additional treatment in a reactive gas medium is carried out. The example of embodiment under consideration uses an elongated gas distributing means, which is employed as an additional treatment system 15 for supplying a reactive gas or mixture thereof. Additional gaseous treatment by means of the system 15 allows uniform accomplishment of chemical processes activated by plasma treatment in the discharge zone to be carried out. The results of experiments on plasma treatment of samples of materials to be treated are depicted as a graphic representation of dependences shown in Figs 5 to 10. In the course of experiments, the treatment processes were carried out with the predetermined discharge parameters which had been selected in order to improve the wettability of the surface to be treated. Samples made of stainless steel, carbon steel, aluminum, polyethylene, polyimide and vinyl chloride were subjected to the treatment process. Figs 5 to 10 present the dynamics of variations in the limiting (wetting) angles of treated samples in the process of aging in atmoshere under normal conditions.

According to the present invention, the plasma treatment of dielectric materials substantially enhances the water absorbing capacity of their surfaces. After plasma treatment, the limiting wetting angle for polyimide was 15° (see Fig. 9), for vinyl chloride 17° (see Fig 10), for polyethylene 20° (see Fig. 8). After 10-day holding of the samples, the limiting wetting angles of the materials mentioned were: 38° for a polyimide sample, 30° for a vinyl chloride sample and 35° for a polyethylene sample.

Plasma treatment of metal samples has also shown a substantial increase in the water absorbing capacity of the surfaces (although to a lesser extent as compared to dielectrics). After plasma treatment, the limiting wetting angles were: 15 for a stainless steel sample (see Fig. 5), 20 for a carbon steel sample (see Fig. 6), 10 for an aluminum sample (see Fig. 7). The value of the limiting wetting angle of the treated stainless steel sample surface became stable within 20 days of aging procedure in atmosphere (under normal conditions). The value of the limiting wetting angle of the stainless steel sample after the aging procedure was 35°. When the carbon steel sample was subjected to aging procedure, the limiting wetting angle thereof had stabilized within 6 days at 35°. Regarding the aluminum sample, the value of the limiting wetting angle had stabilized at the angle of 28° within 25 days after plasma treatment. The above experimental data confirm the possibility of a substantial increase in the water absorbing capacity of the surface to be treated, as a form of surface modification, and in producing stable surface properties for a prolonged period after treatment process. Modification of properties, including the water absorbing capacity, of the material to be treated is carried out at the increased uniformity level over the entire surface under the selected plasma treatment conditions. Uniform treatment of the surface and achievement of stable properties of the surface to be treated are provided through the usage of an extended pulsating discharge under atmospheric pressure, which possesses high stability and is uniform along the discharge electrode.

Industrial Application

The invention may be used in different plasma technologies, including those aimed to increase the water absorbing and water repelling capacities of the surface to be treated, for improving the adhesion and corrosion resistance thereof. The process and apparatus for treating materials, as well as the process of plasma generation may be employed in industrial units for cleaning, modifying and polishing metal and dielectric surfaces, as well as for applying coatings thereon.

The patentable invention is described by the above examples of a preferred embodiment. Those skilled in the art understand that in the case of a concrete industrial realization of the patentable process and apparatus, insignificant modifications of the above examples of the embodiment may take place without departing from the object of the invention.

Claims

CLAIMSWhat we claim is:

1. A process of plasma treatment of materials under atmospheric pressure, involving supplying of a working gas stream into a discharge gap from the side of a discharge electrode, igniting a pulsating electric discharge by means of an elongated discharge electrode arranged opposite to the surface to be treated, to which a cyclically variable voltage is supplied, and maintaining an extended pulsating discharge under atmospheric pressure for generating plasma during treatment of the material, characterized in that plasma generation is effected by supplying gas stream at an angle of 10° to 60° to the longitudinal axis or plane of symmetry of an elongated electrode toward the surface to be treated, with the gas stream being supplied uniformly along the surface of the elongated discharge electrode.

2. A process as claimed in claim 1, wherein an elongated discharge electrode formed as a metal core or metal string (1) is used.

3. A process as claimed in claim 1, wherein an elongated discharge electrode formed as a metal tape is used.

4. A process as claimed in claim 1, wherein at least one ignitor electrode (4) is used for igniting a pulsating electric discharge.

5. A process as claimed in claim 1, wherein a pulsating electric discharge is ignited between an elongated discharge electrode and a grounded electrode arranged below a substrate (10) of dielectric material to be treated.

6. A process of plasma generation, including supplying of a gas stream into a discharge gap from the side of a discharge electrode under external atmospheric pressure, igniting a pulsating electric discharge by means of at least one elongated discharge electrode to which a cyclically variable voltage is supplied, and maintaining an extended pulsating discharge under atmospheric pressure, characterized in that plasma is generated by supplying a gas stream at an angle of 10° to 60° to the longitudinal axis or plane of symmetry of the elongated electrode, with gas stream being supplied uniformly over the surface of the elongated electrode.

7. A process as claimed in claim 6, wherein an elongated discharge electrode formed as a metal core or metal string (1) is used.

8. A process as claimed in claim 1, wherein an elongated discharge electrode formed as a metal tape is used.

9. A process as claimed in claim 1, wherein at least one ignitor electrode (4) is used for igniting a pulsating electric discharge.

10. A process as claimed in claim 1, wherein a pulsating electric discharge is struck between an elongated discharge electrode and a grounded electrode which is separated from the elongated discharge electrode by a dielectric layer.

11. Apparatus for plasma treatment of materials under atmospheric pressure comprising at least one elongated discharge electrode with terminals (2,3) for connection to a power supply source, a gas distributing means for blowing a working gas stream along the elongated discharge electrode arranged opposite to the surface to be treated, and a system for feeding the material to be treated into a discharge space, characterized in that the gas distributing means comprises a housing (5) of dielectric material within which are formed inclined gas supply channels (8) having outlet openings arranged opposite to the discharge electrode, with said channels being oriented at an angle of from 10 to 60 to the longitudinal axis or plane of symmetry of the elongated discharge electrode toward the surface to be treated and being uniformly distributed over the surface of the housing (5) of the gas distributing means, along the length of the elongated discharge electrode.

12. Apparatus as claimed in claim 1 1, wherein inclined gas supply channels (8) are formed as Laval nozzles.

13. Apparatus as claimed in claim 11, wherein said apparatus comprises at least one ignitor electrode (4).

14. Apparatus as claimed in claim 11, wherein said apparatus comprises a system for feeding the material to be treated in the form of a ribbon (12) through a discharge space by means of winding drums (13).

15. Apparatus as claimed in claim 14, wherein said apparatus includes an ultraviolet radiation source (14) and/or a gas supply system (15) which are arranged above the movable ribbon (12).

16. Apparatus as claimed in claim 11, wherein a system for feeding the material to be treated into the discharge space includes at least one unit (9) for reciprocating a substrate (10) manufactured of material to be treated relative to an elongated discharge electrode.

17. Apparatus as claimed in claim 11, wherein an elongated discharge electrode is formed as a metal core.

18. Apparatus as claimed in claim 1 1, wherein an elongated discharge electrode in formed as a metal string (1) with a tension spring.

19. Apparatus as claimed in claim 11, wherein an elongated discharge electrode is formed as a metal tape.

20. Apparatus as claimed in claim 11, wherein said apparatus comprises at least one grounded metal electrode arranged below a substrate (10) or a ribbon (12) of the material to be treated.