Improved shielding for atmospheric pressure plasma jet coating deposition onto substrates

Abstract

The present invention relates to a method for plasma coating an object having an object contour, said method comprising the steps of: a. providing a replaceable shield (2), said replaceable shield comprising a jet inlet (22), a nozzle outlet (24), and a sidewall (21) extending from the jet inlet to the nozzle outlet, said nozzle outlet comprising an edge (25) that is essentially congruent with at least a portion of the object contour, whereby the shield preferably comprises identification means associated with the nozzle outlet edge; said method further comprising the steps of: b. removably attaching said replaceable shield to a jet outlet of a plasma jet generating device; and c. minimizing a gap between the nozzle outlet and the object by placing the object at the nozzle outlet so that the object contour fits snugly against the nozzle outlet edge to a distance of at least 0.1 mm, preferably at most 5 mm; and d. plasma coating the object with low-temperature oxygen-free plasma at an operating pressure preferably at most 10% higher than atmospheric pressure, wherein the plasma coating step is performed by providing a plasma jet within a shield by a plasma jet generating device and injecting a coating precursor within the plasma jet into the shield, thereby creating the operating pressure; Thereby, the object is plasma coated in an oxygen-deficient plasma zone, the method comprising the additional step of identifying the applied shield before applying the plasma jet.

Description

[Technical field]

[0001] Technical Field The present invention relates to the technical field of plasma deposition. Thus, the present invention may relate to IPC H05H 1 / 24 and / or IPC B01J 19 / 08. [Background technology]

[0002] background Coating by plasma deposition offers many advantages over other coating techniques, especially wet techniques in which the coating is applied by exposing the object to a liquid containing the coating material: for example, plasma coating allows for very thin coating layers, which allows for the coating of objects with all types of shapes, there is little loss of coating material, etc. Summary of the Invention [Problem to be solved by the invention]

[0003] Plasma coating techniques can generally be divided into vacuum and atmospheric techniques. The present invention relates to atmospheric plasma coating, where the pressure of the plasma is close to atmospheric pressure. In practice, the plasma pressure may differ slightly from atmospheric pressure, for example, slightly overpressure. Atmospheric plasma coating techniques have a great advantage over vacuum plasma coating techniques, because no vacuum chamber is required and the coating process can be easily carried out in-line.

[0004] Many plasma coating processes have been disclosed in the patent documents EP 0 217 399 A2, US 3,914,573 A, US 2017 / 095929 A1 and EP 1 875 785 A1. These documents relate to a specific type of plasma spray gun that heats the plasma to over 1000° C. and sprays the plasma at high speed onto a substrate. Processes such as those disclosed in US 3,914,573 A can generally be used to coat metal objects such as steel with material particles, which have a melting temperature well above the plasma temperature. A high plasma temperature is necessary to soften the material particles for improved coating on the substrate.

[0005] Patent application DE 10 2017 217069 A1 discloses a rotary unit for a coating lance device for internal thermal coating. It is proposed that the rotary drive is designed as a hollow shaft motor coaxially to the axis of rotation of the tool holder, the tool holder and the coating material supply and process media supply being arranged centrally with respect to the hollow shaft motor. This document is particularly relevant for providing a metallic coating on an aluminum cylinder crankcase. The thermal coating processes disclosed therein are powder plasma spraying, wire spraying processes such as plasma transferred wire arc (PTWA) and electric arc wire spraying (LDS), or HVOF spraying (high velocity flame spraying). These are all intense and high-temperature processes that are not suitable for use in coating other types of substrates, in particular non-metallic substrates. These methods also make stringent requirements on the components of the device, in particular the nozzle and the materials used for its components. Furthermore, the device of DE 10 2017 217069 1 relates to a dedicated device intended to process only one type and shape of substrate.

[0006] However, the present invention relates to a different type of atmospheric plasma coating process and an apparatus therefor, which allows the coating of molecular substances on all types of substrates, including metal and non-metallic substrates, in particular also plastic and / or glass substrates, which have melting and / or flow temperatures well below 1000°C, sometimes even below 200°C, 150°C, 100°C or even lower. Obviously, the processes and dedicated equipment of plasma spray guns disclosed in DE 10 2017 217069 A1, EP 0 217 399 A2, US 3,914,573 A, US 2017 / 095929 A1 and EP 1 875 785 A1 cannot be used. A plasma coating technique at low temperatures, generally below 200°C plasma temperatures, is required.

[0007] JP 2008 / 130 503 A discloses an apparatus comprising an atmospheric plasma jet generating means and a treatment chamber, the plasma jet being insertable into the treatment chamber, the treatment chamber comprising an upper part made of resin and a lower part, the upper part and the lower part being separated from each other by a small gap, whereby the apparatus is configured to prevent the ingress of ambient air into the treatment chamber due to overpressure which would cause an escape of gas from the treatment chamber through the small gap.

[0008] The document discloses that the problem is solved by providing an atmospheric pressure plasma jet device capable of elongating the plasma plume so as to efficiently modify the surface regardless of the surface shape of the material.

[0009] However, the device according to this document is not suitable for coating deposition, and the document mentions, inter alia, cleaning and improving hydrophilicity as possible applications.

[0010] Furthermore, the device according to this document is not suitable for in-line processing of continuous substrates. This document describes, in particular, an opening area adjustment means (or shutter) for loading and unloading the processing object. Furthermore, this document describes that the size of the processing object is substantially equal to the opening surface of the upper part of the processing chamber. Thereby, this document provides a batch processing chamber.

[0011] Furthermore, the device according to this document is not suitable for easy cleaning, long term maintenance and / or in-line treatment of multiple irregular surfaces.

[0012] JP 2007 / 323 812 A discloses an atmospheric pressure plasma device comprising a first reaction space and a mixed gas container containing a mixed gas region, the device being configured to inject a primary plasma jet from the first reaction space into the mixed gas region, and to inject a mixed gas containing a reactive gas into the mixed gas region to collide with the primary plasma.

[0013] The apparatus according to this document is not suitable for in-line plasma deposition onto continuous substrates with irregular surfaces. Moreover, the apparatus is not suitable for easy cleaning and / or long-term maintenance.

[0014] The present invention aims to solve at least some of the above problems, thereby enabling low-temperature, in-line atmospheric plasma coating of all types of substrates to obtain uniform coatings. [Means for solving the problem]

[0015] Summary of the Invention In a first aspect, the present invention provides a method for plasma coating an object having an object contour, the method comprising: a. providing a replaceable shield (2), preferably by manufacturing said replaceable shield, said replaceable shield comprising a jet inlet (22), a nozzle outlet (24), and a sidewall (21) extending from said jet inlet to said nozzle outlet, said nozzle outlet having an edge (25) essentially congruent with at least a portion of said object contour, said method further comprising: b. removably attaching the replaceable shield to a jet outlet of a plasma jet generating device; c. minimizing a gap between the nozzle outlet and the object by placing the object at the nozzle outlet such that the object contour fits snugly against the nozzle outlet edge; d. plasma coating said object with a low temperature oxygen-free plasma at an operating pressure preferably at most 10% above atmospheric pressure, said plasma coating being performed by providing a plasma jet within said shield by said plasma jet generating device and injecting a coating precursor within said plasma jet into said shield, thereby creating said operating pressure; Thereby, the object is plasma coated in an oxygen-deficient plasma zone.

[0016] In another aspect, the present invention provides a kit for carrying out the method of the present invention, said kit comprising a plurality of interchangeable shields (2), each shield comprising a jet inlet (22), a nozzle outlet (24) and a sidewall (21) extending from said jet inlet to said nozzle outlet, said nozzle outlet of each shield comprising a nozzle outlet edge that is essentially congruent with at least a portion of an object contour of an object, preferably each shield comprising a nozzle outlet having a nozzle outlet edge that is essentially congruent with a respective portion of the object contour or at least a portion of each object contour of a plurality of types of objects.

[0017] In a further aspect, the present invention provides an apparatus for depositing a coating by means of an atmospheric pressure plasma jet, said apparatus comprising: A plasma jet generating device (1) having a jet outlet (12); a nozzle having an adapter (3) and a replaceable shield (2), the shield having a jet inlet (22), a nozzle outlet (24), and a sidewall (21) extending from the jet inlet to the nozzle outlet; The adapter is configured to removably mount the shield onto the plasma jet generating device, thereby communicatively coupling the jet outlet and the jet inlet.

[0018] In yet another aspect, the present invention provides a method for depositing a coating by an atmospheric pressure plasma jet, the method comprising: Providing an atmospheric pressure plasma jet generating device (1) having a jet outlet (12); providing a shield (2), the shield having a jet inlet (22), a nozzle outlet (24), and a sidewall (21) extending from the jet inlet to the nozzle outlet, the method further comprising: removably attaching the shield to the plasma jet generating device, thereby communicatively coupling the jet inlet and the jet outlet; providing a plasma jet within the shield by the plasma jet generating device to inject a coating precursor within the plasma jet into the shield, thereby creating an overpressure within the shield relative to the environment; Relatively moving a surface of a substrate and the nozzle outlet thereby depositing a coating on the surface.

[0019] The nozzle outlet of the shield can be placed close to the surface of the substrate to be processed, preventing a significant inflow of ambient air due to overpressure in the shield. During coating deposition, the shield can deteriorate, for example, due to the plasma jet deteriorating the shield inner wall and / or the deposition of the coating on the shield inner wall. Additionally, and more importantly, when substrates of different sizes and / or shapes are utilized, a single nozzle cannot provide satisfactory results for each substrate. The present invention allows the shield to be exchanged depending on the application. For in-line coating deposition on large planar surfaces, a shield with a large planar nozzle outlet may be utilized. For in-line coating deposition on non-planar surfaces, a shield with a specially adapted non-planar nozzle may be utilized. For processing of finite irregular samples, the sample may remain fixed and the jet may be moved, whereby the nozzle outlet may be provided with a size small enough to allow closely following the surface of the sample. The invention allows for the in-line plasma coating of all types of objects with low-temperature oxygen-free plasma at an operating pressure slightly above atmospheric pressure, preferably by at most 10%, by providing a plasma jet in a shield by means of a plasma jet generator and injecting the coating precursor into the plasma jet in the shield, thereby generating said operating pressure. The overpressure, in combination with the small gap between the nozzle outlet edge and the surface of the object due to the congruence of the nozzle outlet edge with the contour of the object, allows the exposure of the surface of the object to an oxygen-deficient plasma zone, which in turn leads to excellent coating results, especially in terms of uniformity and stability, including improved adhesion of the coating to the surface and reduced degradation in time. Furthermore, the presence of an oxygen-deficient plasma zone allows the use of a large number of precursor molecules that would otherwise not have been used due to their reactivity with oxygen.

[0020] It is further noted that in the present invention, the plasma temperature is preferably kept low, preferably below 200°C, more preferably below 180°C, more preferably below 160°C, more preferably below 140°C, more preferably below 130°C, more preferably below 120°C, more preferably below 110°C, more preferably below 100°C, more preferably below 90°C, more preferably below 80°C, more preferably below 70°C, more preferably below 60°C, more preferably below 50°C.

[0021] The shield of the present invention can be easily removed from the plasma jet generating device and replaced with a replacement shield of the same type (e.g. when repairing a defective shield) or with another shield of the same type but with a different nozzle exit edge, i.e. a nozzle exit edge that is essentially congruent with another object contour or another part of the object contour of the object. In such cases, it is important to start the plasma process when it can be guaranteed that a correctly positioned shield has been installed. Thus, a further aspect of the present invention relates to an exchangeable shield (2) for use in an atmospheric plasma device, the shield comprising a jet inlet (22), a nozzle exit (24) and a side wall (21) extending from the jet inlet to the nozzle exit, the nozzle exit comprising an edge (25) that is essentially congruent with at least a part of the object contour, whereby the shield comprises an identification means, preferably associated with the nozzle exit edge. In this specification, the identification means allows identification of the shield, preferably the nozzle exit edge, and thus the process in which the shield is used. For example, the shield may be selected for a plasma coating process of a first part of an object of a first type. Thus, the identification of the shield improves quality control, since the shield can be used to ensure that only a process for plasma coating the first portion of the first type of object is performed. It should be clear that such a shield or a set of such shields may preferably be used with the methods described herein, may be used in the apparatus described herein, and may be used in the kit described herein.

[0022] The identification means of the shield may comprise an identification tag, which may be, for example, a radio frequency identification tag ("RFID"), a bar code, a quick response ("QR") code, a mechanical bit set, a key-like structure, etc. Preferably, the identification means comprises an RFID. Thus, the invention also relates to an apparatus for depositing a coating by means of an atmospheric pressure plasma jet, said apparatus comprising: A plasma jet generating device (1) having a jet outlet (12); a nozzle having an adapter (3) and a replaceable shield (2), the shield having a jet inlet (22), a nozzle outlet (24), and a sidewall (21) extending from the jet inlet to the nozzle outlet; the nozzle outlet has an edge (25) that is essentially congruent with at least a portion of the object contour, whereby the shield has identification means associated with the nozzle outlet edge; the adapter is configured to removably mount the shield onto the plasma jet generating device, thereby communicatively coupling the jet outlet and the jet inlet; The apparatus comprises an identification means reader module for reading the identification means associated with the nozzle outlet edge.

[0023] Thereby, the identification means reader module can be selected taking into account the identification means, i.e. if the identification means comprises an RFID, the identification means reader module preferably comprises an RFID tag reader module. Thus, if the identification means comprises an RFID, a barcode, a QR code, a mechanical bit set or a key-like structure, the identification means reader module of the device preferably comprises an RFID reader module, a barcode reader module, a QR code reader module, a mechanical bit set reader module or a keyhole-like structure, respectively.

[0024] Correspondingly, the invention also relates to a method as described above, comprising the additional step of identifying the provided shield before providing the plasma jet.

[0025] This identification can preferably be performed by reading out an identification means provided on the shield.

[0026] This identifying step is also preferably performed in conjunction with a step of preventing the plasma jet from being provided if the identification of the provided shield does not correspond to a set of predefined process conditions.

[0027] The set of predefined process conditions includes the following parameters: the nozzle exit edge, and / or Plasma parameters such as gas flows, pressure and temperature The present invention may relate to any one or any combination of the above.

[0028] For example, the method may be performed to treat an object having a particular object contour that needs to be treated, using a shield having a particular nozzle exit edge that is congruent with said object contour. If an incorrect type of shield is installed, the identification as in the method allows to prevent the plasma jet from being provided, for example by holding the process and / or by informing an operator of the mismatch between the required type of nozzle exit edge and the nozzle exit edge of the installed shield.

[0029] Further advantages, features and examples of the present invention are disclosed in the detailed description. [Brief description of the drawings]

[0030] [Figure 1a] 1 is a perspective view of an embodiment of an apparatus according to the present invention; [Figure 1b] 1 is a perspective view of an embodiment of an apparatus according to the present invention; [Figure 2a] FIG. 1 is a perspective view of an embodiment of a shield according to the present invention. [Figure 2b] FIG. 1 is a perspective view of an embodiment of a shield according to the present invention. [Figure 2c] FIG. 1 is a perspective view of an embodiment of a shield according to the present invention. [Figure 2d] FIG. 1 is a perspective view of an embodiment of a shield according to the present invention. [Diagram 3]FIG. 1 is a perspective view of an embodiment of a shield according to the present invention. [Figure 4] 1 is a perspective view of an embodiment of an adapter and shield according to the present invention; [Figure 5a] 1 is a longitudinal cross-sectional view of an embodiment of a shield according to the present invention; [Figure 5b] FIG. 2 is a side view of an embodiment of a shield according to the present invention. [Figure 6] FIG. 13 is a side view of an alternative embodiment of a shield according to the present invention. [Figure 7] FIG. 1 is a cross-sectional view of an apparatus having a shield according to the present invention, which is particularly preferred for plasma coating of powders. [Figure 8] FIG. 1 is a cross-sectional view of an apparatus with a shield according to the invention, which is particularly preferred for the plasma coating of textiles. [Figure 9] FIG. 1 is a perspective view of a shield according to the invention, the edge of which is manufactured to be congruent with an axially symmetrical object; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] Detailed Description of the Invention The present invention relates to an exchangeable shield, an apparatus and a method for depositing a coating by an atmospheric pressure plasma jet.Furthermore, the present invention relates to a kit.The present invention is summarized in the corresponding section above.In the following, the present invention is explained in detail, preferred embodiments are described and the present invention is illustrated through examples.

[0032] Unless otherwise defined, all terms used in disclosing the present invention, including technical and scientific terms, have the meanings commonly understood by those of ordinary skill in the art to which the present invention belongs. Definitions of terms are included by way of further guidance to better appreciate the teachings of the present invention.

[0033] As used herein, the following terms have the following meanings. As used herein, "a," "an," and "the" refer to both singular and plural referents unless the context clearly dictates otherwise. As an example, "a compartment" refers to one or more than one compartment.

[0034] "About," as used herein to refer to a measurable value such as a parameter, amount, time period, and the like, is intended to encompass a variation of no more than + / -20%, preferably no more than + / -10%, more preferably no more than + / -5%, even more preferably no more than + / -1%, and even more preferably no more than + / -0.1% of the specified value and from the specified value, to the extent that such variations are appropriate for the practice of the disclosed invention. However, it should be understood that the value to which the modifier "about" refers is itself specifically disclosed.

[0035] As used herein, "comprise," "comprising," "comprises," and "comprised of" are synonymous with "include," "including," "includes," or "contain," "containing," and are inclusive or open-ended terms specifying the presence of what follows, e.g., a component, but do not exclude or preclude the presence of other, unrecited components, features, elements, materials, or steps that are known in the art or disclosed herein.

[0036] The recitation of numerical ranges by endpoints includes all numbers and fractions subsumed within that range, as well as the recited endpoints.

[0037] In one aspect of the invention, the invention provides a method for depositing a coating by means of an atmospheric pressure plasma jet, comprising several steps: A plasma jet generating device is provided, comprising a jet outlet; A shield is manufactured, having an edge that is congruent with the contour of the object to be treated; The shield comprises a jet inlet, a nozzle outlet, and a sidewall extending from the jet inlet to the nozzle outlet; The shield can be removably mounted on the plasma jet generating device, whereby the jet inlet and the jet outlet are communicatively coupled; A plasma jet can be provided in the shield by the plasma jet generating device; A coating precursor can be injected into the plasma jet in the shield; An overpressure can be created in the shield with respect to the environment; A surface of a substrate can be moved relative to the nozzle outlet, whereby a coating can be deposited on the surface.

[0038] In another aspect, the present invention provides a kit. The kit may be configured for an atmospheric pressure plasma jet generating device including a jet flow outlet. The nozzle kit may include an adapter and a plurality of replaceable shields. Each shield includes a jet flow inlet, a nozzle outlet, and a sidewall extending from the jet flow inlet to the nozzle outlet. The adapter may be configured to removably mount one of the shields on the plasma jet generating device, thereby communicatively coupling the jet flow outlet and the jet flow inlet.

[0039] In a further aspect, the present invention provides an apparatus for depositing a coating by an atmospheric pressure plasma jet, the apparatus comprising a plasma jet generating device comprising a jet flow outlet, the apparatus further comprising an adapter and a replaceable shield, the shield comprising a jet flow inlet, a nozzle outlet and a sidewall extending from the jet flow inlet to the nozzle outlet, the adapter configured to removably mount the shield onto the plasma jet generating device, thereby fluidly coupling the jet flow outlet and the jet flow inlet.

[0040] The nozzle kit according to the second aspect may be used in the device according to the third aspect and / or in the method according to the first aspect. The method according to the present invention may be performed by the device according to the present invention. Therefore, the skilled person will recognize that the aspects of the present invention are interrelated. Thus, each feature disclosed in this document, i.e. above or below, may relate to each aspect of the present invention, even if it is disclosed in relation to a specific aspect.

[0041] As used herein, "atmospheric pressure" means that the pressure is approximately or roughly the same as the pressure of the surrounding environment. This term distinguishes the present plasma technology from low and high pressure plasma technologies that require the reaction vessel to maintain a substantial pressure differential with the environment. Thus, those skilled in the art of plasma technology will recognize that "atmospheric pressure" as used herein should not be interpreted as "atm", a unit of pressure defined as 101 325 Pa.

[0042] As used herein, "communicatively coupled" refers to mass flow, i.e., fluid, gas and / or plasma flow, such that the jet outlet of the plasma jet generating device and the jet inlet of the shield are communicatively coupled such that the plasma jet exiting the jet outlet enters the shield via the jet inlet.

[0043] As used herein, "plasma jet" refers to the plasma jet and / or the afterglow of the plasma jet. For example, a coating precursor injected into the "plasma jet" in a shield may refer to a coating precursor injected into the plasma jet in a shield and / or the afterglow of the plasma jet.

[0044] The method of the present invention comprises the steps of: a. providing, preferably manufacturing, a replaceable shield (2), said replaceable shield having a jet inlet (22), a nozzle outlet (24), and a sidewall (21) extending from said jet inlet to said nozzle outlet, said nozzle outlet having an edge (25) that is essentially congruent with at least a portion of an object contour, said method further comprising: b. removably attaching the replaceable shield to a jet outlet of a plasma jet generating device; c. minimizing a gap between the nozzle outlet and the object by placing the object at the nozzle outlet such that the object contour fits snugly against the nozzle outlet edge; d. plasma coating said object with a low temperature oxygen-free plasma at an operating pressure preferably at most 10% above atmospheric pressure, said plasma coating being performed by providing a plasma jet within said shield by said plasma jet generating device and injecting a coating precursor into said plasma jet within said shield, thereby creating said operating pressure; Thereby, the object is plasma coated in an oxygen-deficient plasma zone.

[0045] In step a, the exchangeable field is manufactured in particular with an edge that is congruent with at least a part of the object contour. Thus, when coating different types of objects, different shields can be manufactured, each of these shields having a congruent edge for the respective type of object. Thus, the method is also applicable to plasma coating multiple types of objects, each type of object with a different object contour, step a being carried out for each type of object, whereby multiple exchangeable shields are manufactured, each shield comprising a nozzle outlet with a nozzle outlet edge that is essentially congruent with at least a part of the object contour of the respective object. In a preferred embodiment, the shield is manufactured using 3D printing techniques, which allow to produce very complex edges sufficiently quickly and reliably.

[0046] The method particularly relates to low temperature plasma, whereby preferably the plasma temperature is below 120°C, more preferably below 70°C.

[0047] The kit of the present invention comprises a plurality of interchangeable shields (2), each shield comprising a jet inlet (22), a nozzle outlet (24), and a sidewall (21) extending from the jet inlet to the nozzle outlet, and each shield's nozzle outlet comprising a nozzle outlet edge that is essentially congruent with at least a portion of the object contour of the object, preferably each shield comprising a nozzle outlet having a nozzle outlet edge that is essentially congruent with a respective portion of the object contour or at least a portion of each object contour of a plurality of types of objects.

[0048] To allow easy removal of the first shield and easy installation of the second shield, preferably the shield is removably attached to the jet flow outlet by an adapter (3), the adapter being configured to removably mount the shield onto the plasma jet generating device, thereby communicatively coupling the jet flow outlet of the plasma jet generating device and the jet flow inlet of the shield.

[0049] During step d, for example to perform in-line coating, an object may be moved relative to the nozzle outlet and the edge, whereby said edge is preferably maintained at a distance of at least 0.1 mm and at most 5 mm, preferably at least 0.2 mm and at most 2 mm, more preferably at least 0.5 mm and at most 1 mm, of said surface of said substrate.

[0050] In a preferred embodiment, the object profile is essentially the same along the longitudinal direction and said relative movement comprises a relative translation along said longitudinal direction. This is especially true for plate- or sheet-like objects which may be non-planar, i.e. have a non-linear cross section perpendicular to the longitudinal direction.

[0051] In a preferred embodiment, the edge is a first edge that is circumferentially congruent with the object contour, whereby the shield comprises a second edge that is an object inlet edge that is circumferentially congruent with the object contour, whereby the relative movement comprises a movement of the object in a longitudinal direction from the object inlet edge to the first edge through a treatment chamber in the shield. This is particularly useful when the object is a fiber having a profile with an essentially circular cross section that is identical in the longitudinal direction, whereby the method according to claim 9 is preferably used, and whereby the first and second edges comprise circular openings with a diameter that is congruent with the cross section of the fiber, whereby the fiber can pass through the openings of the first and second edges. This is also particularly useful when the object is powder which is sprayed along the longitudinal direction to form a powder beam having a profile with an essentially circular cross-section with a diameter which is the same in the longitudinal direction or which varies in the longitudinal direction, whereby the method according to claim 9 is preferably used, and the first edge and the second edge are provided with respective circular openings with respective diameters which are congruent with the cross-section of the powder beam at the location of the first edge and the second edge, respectively, whereby powder can pass through the openings of said first and second edges.

[0052] In another preferred embodiment, the object profile is essentially axially symmetric about a central axis and said relative movement comprises relative rotation about said central axis, which allows rapid and reliable treatment of the object surface by rotating the object or shield, or both, about the central axis through 360° or an integer multiple of 360°, for example for multiple coating steps.

[0053] Preferably, the kit also comprises a plasma jet generating device to which each of the plurality of shields can be attached. The kit may comprise one plasma jet generating device, or two or more, for example two, three, four or more, plasma jet generating devices.

[0054] The device of the present invention comprises: A plasma jet generating device (1) having a jet outlet (12); a nozzle having an adapter (3) and a replaceable shield (2), the shield having a jet inlet (22), a nozzle outlet (24), and a sidewall (21) extending from the jet inlet to the nozzle outlet; The adapter is configured to removably mount the shield onto the plasma jet generating device, thereby communicatively coupling the jet outlet and the jet inlet.

[0055] The nozzle outlet of the shield can be placed very close to the surface of the substrate to be treated, and an overpressure in the shield can prevent a significant inflow of ambient air. During coating deposition, the shield can be degraded and / or contaminated, for example due to the plasma jet degrading the shield inner wall and / or the deposition of the coating on the shield inner wall. In addition, when substrates of different sizes and / or shapes are utilized, a single nozzle cannot provide satisfactory results for each substrate. The present invention allows the shield to be exchanged depending on the application. For in-line coating deposition on large planar surfaces, a shield with a large planar nozzle outlet and a large precursor throughput may be utilized. For in-line coating deposition on non-planar surfaces, a shield with a specially adapted non-planar nozzle outlet may be utilized. For processing of finite irregular samples, the sample may remain fixed and the plasma jet generating device may be moved, whereby the nozzle outlet can be provided with a size small enough to allow closely following the surface of the irregular sample. If a first coating precursor used in a first coating deposition on a first substrate is undesirable in a second coating deposition on a second substrate, the nozzle may be changed to avoid contamination with the first coating precursor during the second coating deposition.

[0056] In a preferred embodiment, the shield comprises a flange at the jet inlet attached to the side wall. The adapter may comprise a retaining wall with an opening having a size and shape adapted to hold the flange. The adapter and the plasma jet generating device may comprise complementary mounting means configured to mount the adapter to the plasma jet generating device. The adapter may be configured to press the flange of the shield to the plasma jet generating device via the retaining wall at a position where the jet outlet and the jet inlet are communicably coupled. Preferably, the flange comprises a planar surface surrounding the jet inlet. Preferably, the flange is adapted to be pressed by the adapter against the plasma jet generating device to avoid a significant inflow of ambient air into the shield via the jet inlet. Thereby, the flange has a dual purpose of avoiding a significant inflow of ambient air into the shield via the jet inlet and mounting the shield on the jet generating device via the adapter. The shield comprises a length along which the jet inlet and the nozzle outlet are spatially separated.

[0057] Preferably, the flange is essentially perpendicular to said length direction.Preferably, said planar surface of said flange is essentially perpendicular to said length direction.

[0058] Preferably, the shield is of one-piece construction. The shield may be manufactured by injection molding. The shield may be manufactured by 3D printing. Preferably, the shield comprises an insulating material, more preferably a plastic. The nozzle outlet of the shield comprises an edge. The nozzle outlet of the shield may comprise a planar edge, i.e. the nozzle outlet is planar. The nozzle outlet of the shield may comprise a non-planar edge, i.e. the nozzle outlet is non-planar. This allows for in-line coating of non-planar surfaces, whereby a small distance is maintained between each portion of the edge and the surface.

[0059] The coating precursor may be injected into the plasma jet within the shield. The jet outlet of the plasma jet generating device may comprise a plurality of outlet compartments. The plasma jet generating device may be configured to provide a plasma jet from a first compartment and provide a coating precursor from a second compartment. The jet outlet may comprise two concentric cylindrical walls defining an inner compartment for providing the coating precursor and an outer compartment for providing the plasma jet. The jet outlet may comprise a rectangular outlet divided into three compartments by two inner walls defining a middle compartment for providing the coating precursor and two outer compartments for providing the plasma jet.

[0060] In a preferred embodiment, the side wall of the shield comprises at least one precursor inlet, preferably at least two precursor inlets, such as two, three, four or more precursor inlets. The precursor inlets may comprise a tubular hollow body comprising a first outer end communicatively coupled to the interior of the shield and a second outer end for communicatively coupling to a precursor source. The tubular body may be cylindrical. The tubular body may comprise one or more bends. Coating precursors may be injected into the plasma jet in the shield via the at least one precursor inlet.

[0061] In a preferred embodiment, the jet flow outlet of the plasma jet generating device comprises an opening, and the jet flow inlet of the shield comprises an opening, whereby the opening of the jet flow inlet is larger than the opening of the jet flow outlet. This is advantageous because the expansion leads to a velocity reduction and a pressure increase, thereby helping to create an overpressure in the shield with respect to the environment. Furthermore, this is advantageous because the sudden expansion can cause turbulence and / or recirculation and therefore mixing of the components present in the corresponding part of the shield. Preferably, the shield comprises a length between the jet flow inlet and the nozzle outlet, and said at least one precursor flow inlet is communicatively coupled to the inside of the shield within a distance of the jet flow inlet equal to at most 50% of said length, preferably at most 40% of said length, more preferably at most 30% of said length. This is advantageous because the inflow of precursors occurs in a region where recirculation also occurs. Furthermore, this is advantageous since the inflow of precursors occurs in a direction that is substantially not parallel to the plasma jet inflow at the jet inlet, preferably in a direction that is essentially perpendicular to the plasma jet inflow at the jet inlet, preferably essentially parallel to the length direction, thereby further increasing turbulence.

[0062] In a preferred embodiment, the side wall of the shield comprises a tapered portion. This tapered portion can expand the cross section of the shield from the jet inlet towards the jet outlet, for example to deposit a coating on a large, essentially planar surface. The tapered portion can reduce the cross section of the shield from the jet inlet towards the jet outlet, for example to focus the deposition of the coating in a narrow spot, thereby optionally creating a small nozzle outlet to allow the movement of the nozzle outlet to closely follow an irregular surface. Preferably, the tapered portion is adapted such that the nozzle outlet comprises a smaller opening than the jet inlet. Preferably, the tapered portion extends over at least 20% of the length of the shield.

[0063] In a preferred embodiment, the nozzle comprises an equalizing means. Preferably, the shield comprises said equalizing means, preferably on the inside. The equalizing means may comprise a flow disrupting element. The flow disrupting element may comprise a plurality of inclined surfaces. The flow disrupting element may comprise a plurality of layers, each layer comprising a number of inclined surfaces. The flow disrupting element may comprise a surface that is at an angle of at least 20° and at most 70° with the length of the shield.

[0064] In a preferred embodiment, the nozzle is adapted for cooling. Preferably, the side wall of the shield comprises a channel for the passage of a cooling fluid. The channel is preferably located at a distance from the nozzle outlet of at most 60%, more preferably at most 50%, even more preferably at most 45% of the length of the shield.

[0065] In a preferred embodiment, the device may comprise a transport means for in-line processing of planar or non-planar surfaces of continuous substrates, whereby the device is configured to maintain each part of the edge of the nozzle outlet at a distance of at least 0.1 mm and at most 5 mm, preferably at least 0.2 mm and at most 2 mm, more preferably at least 0.5 mm and at most 1 mm, of said surface of said substrate. The method may comprise the step of moving the surface of the substrate and the nozzle outlet relatively, preferably whereby each part of said edge is maintained at a distance of at least 0.1 mm and at most 5 mm, preferably at least 0.2 mm and at most 2 mm, more preferably at least 0.5 mm and at most 1 mm, of said surface of said substrate, whereby a coating is deposited on said surface. A gap of said size between the edge of the nozzle outlet and the surface of the substrate is particularly suitable for preventing the inflow of ambient air due to slight overpressure in the shield, while at the same time allowing a sufficient outflow of gas from the shield.

[0066] In a preferred embodiment, the plasma jet generating device is configured to generate the plasma jet by dielectric barrier discharge or corona discharge. Preferably, the plasma jet generating device comprises an AC power supply.

[0067] The present invention is further illustrated by the following non-limiting examples, which further illustrate the invention and are not intended, nor should they be construed, as limiting the scope of the invention.

[0068] Working Example Example 1: First Device At least a part of a first embodiment of an apparatus according to the invention is shown in Figure 1a. The apparatus comprises an atmospheric pressure plasma jet generating device (1) and a nozzle comprising an adapter (3) and a shield (2).

[0069] The plasma jet generating device (1) comprises a body (11) with a cylindrical outer end. The cylindrical outer end comprises a side wall (14) and an end wall (13) essentially perpendicular to the side wall, in which a jet outlet (12) is provided. The cylindrical outer end comprises a diameter (d5). The jet outlet (12) comprises a diameter (d1). The plasma jet generating device (1) comprises two cylindrical walls defining two compartments within the jet outlet (12), namely an inner compartment for providing a coating precursor and an outer compartment for providing a plasma jet and / or an afterglow. The plasma jet generating device may typically be configured according to claims 1 to 8 of EP 1 844 635 B1 and the corresponding sections of the specification.

[0070] The shield (2) comprises a jet inlet (22), a nozzle outlet (24), and side walls (21a, 21b) extending from the jet inlet (22) to the nozzle outlet (24). The shield comprises a length along which the jet inlet (22) and the nozzle outlet (24) are spaced apart. The shield (2) comprises a flange (26) at the jet inlet, the flange (26) being attached to the side wall (21a) at an edge (23) of the jet inlet (22) and surrounding the jet inlet (22). The jet inlet comprises a diameter (d2). The nozzle outlet comprises a diameter (d6). The shield comprises a tapered portion (21a) located within a distance of the jet inlet equal to at most 50% of the length of the shield along the length. The tapered portion (21a) narrows the shield from the jet inlet towards the nozzle outlet, so that the nozzle outlet diameter (d6) is smaller than the jet inlet diameter (d2), which is larger than the jet outlet diameter (d3), which allows for the advantageous results described in the detailed description. The nozzle outlet has a planar edge (25), i.e. the edge of the nozzle outlet lies essentially in a plane. Preferably, this plane is essentially perpendicular to the length.

[0071] The adapter (3) comprises a retaining wall (31) with a circular opening (32) with a diameter (d3) essentially equal to or slightly greater than the sum of the diameter (d2) of the jet inlet and twice the thickness of the side wall (21a). The opening (32) is thereby sized and shaped to hold the flange (26) of the shield (2) and in particular to press the flange (26) onto the end wall (13) of the plasma jet generating device (1). The retaining wall has a diameter (d4) essentially equal to the diameter (d5) of the outer end. The adapter further comprises two curved side wall portions (33) for positioning over the side wall (14) of the outer end of the plasma jet generating device, and two arms (34) with attachment means (35) for attaching the adapter to the plasma jet generating device, thereby pressing the flange (26) against the end wall (13) while maintaining the jet outlet (12) and the jet inlet (22) in a communicatively coupled state. The attachment means may include holes for attaching the elastic tensioning mechanism.

[0072] Example 2: Apparatus At least a part of a second embodiment of the apparatus according to the invention is shown in figure 1b. The apparatus comprises an atmospheric pressure plasma jet generating device (1') and a nozzle with an adapter (3') and a shield (2').

[0073] The plasma jet generating device (1') comprises a body (11') with a cubic outer end. The cubic outer end comprises a side wall (14') and an end wall (13') essentially perpendicular to the side wall, in which a jet outlet (12') is provided. The cubic outer end comprises a height (h5) and a width (l5). The jet outlet (12') comprises a height (h1) and a width (l1). The plasma jet generating device (1') comprises two inner walls defining three compartments within the jet outlet (12'), namely an inner compartment for providing a coating precursor and two outer compartments for providing a plasma jet and / or an afterglow. The plasma jet generating device may typically be constructed according to claims 9 to 15 of EP 1 844 635 B1 and the corresponding sections of the specification.

[0074] The shield (2') comprises a jet inlet (22'), a nozzle outlet (24') and a side wall (21') extending from the jet inlet (22') to the nozzle outlet (24'). The shield comprises a length along which the jet inlet (22') and the nozzle outlet (24') are spaced. The side wall comprises a uniform rectangular cross section essentially perpendicular to the length. The shield (2') comprises a flange (26') at the jet inlet, which is attached to the side wall (21') at an edge (23') of the jet inlet (22') and surrounds the jet inlet (22'). The jet inlet and the nozzle outlet comprise a height (h2) and a width (l2). The nozzle outlet (24') comprises a planar edge (25'), i.e. the edge of the nozzle outlet lies essentially in a plane. Preferably, this plane is essentially perpendicular to the length.

[0075] The adapter (3') comprises a retaining wall (31') with a rectangular opening (32') with a height (h3) and width (l3) essentially equal to or slightly greater than the sum of the height (h2) and width (l2) of the jet inlet and twice the thickness of the side wall (21'), respectively. The opening (32') thereby has a size and shape configured to retain the flange (26') of the shield (2') and in particular to press the flange (26') onto the end wall (13') of the plasma jet generating device (1'). The retaining wall has a height (h4) and width (l4) essentially equal to the height (h5) and width (l5) of the outer end, respectively. The adapter further comprises two side wall portions (33') for positioning over the side wall (14') of the outer end of the plasma jet generating device, and two arms (34') with attachment means (35') for attaching the adapter to the plasma jet generating device, thereby pressing the flange (26') against the end wall (13') while maintaining the jet outlet (12') and the jet inlet (22') in a communicatively coupled state. The attachment means may comprise holes for attaching an elastic tensioning mechanism.

[0076] Example 3: Shield Shape In this embodiment, reference is made to Figures 2a, 2b, 2c and 2d. Specific features disclosed in this embodiment may relate to the shields of Examples 1 and 2 above.

[0077] The shield comprises a jet inlet (22", 22''') and a nozzle outlet (24", 24'''). Additionally, the shield comprises a length along which the jet inlet and the nozzle outlet are spatially separated. The shield also comprises side walls (21a", 21b", 21''') extending from the jet inlet to the nozzle outlet. The shield comprises a length along the length, i.e., the distance the jet inlet and the nozzle outlet are separated. The jet inlet comprises an essentially planar edge (23") essentially perpendicular to the length. The shield further comprises a flange (26", 26''') at the jet inlet, which is attached to the side wall and surrounds the jet inlet. The side wall of the shield may have a uniform cross section perpendicular to the length (Figs. 2c and 2d). Alternatively, the side wall of the shield may have a tapered portion (21a") and a portion (21b") having a uniform cross section perpendicular to the length. The side wall of the shield may have a cross section perpendicular to the length that is circular (Figs. 2a and 2b), elliptical, rectangular (Figs. 2c and 2d), square, triangular, pentagonal, hexagonal, diamond, octagonal, star, cross, etc. Preferably, The side wall of the shield comprises a cross section perpendicular to the length direction with a shape adapted to the shape of the jet outlet and further with one or more dimensions larger than the corresponding dimensions of the jet outlet. Most preferably, said shape is circular or rectangular. The shield also comprises a nozzle outlet edge (25", 25''') at the nozzle outlet (24", 24'''). The nozzle outlet edge may be planar (Figures 2a and 2b). The nozzle outlet edge may lie in a plane perpendicular to the length direction. The nozzle outlet edge may also be non-planar (Figures 2c and 2d). Thereby, the nozzle outlet edge may comprise two portions with different distances to the flange. Thereby, the nozzle outlet edge may comprise a portion including a curvature in the length direction.

[0078] Example 4: Further Shielding Features With reference to Figure 3, the shield may comprise at least one, preferably at least two, precursor inlets (27). The precursor inlets are communicatively coupled to the shield, preferably via a sidewall, more preferably within a jet inlet distance of at most 50% of the length of the shield. The precursor inlets may be coupled via a tapered portion (21a) of the sidewall (Figure 3) or alternatively via a straight portion of the sidewall, i.e. parallel to the length.

[0079] With reference to Figures 3 and 4, the adapter may comprise a hinge (36") and a locking mechanism (37") to allow the flange (26") of the shield to be enclosed in order to press the flange (26") against the end wall of the plasma jet generating device via the retaining wall (31") of the adapter, in order to allow the precursor inlet (27, 27"") to protrude and / or for the shield to have a tapered portion (21"") widening the shield from the jet inlet (22"") towards the nozzle outlet (24"").

[0080] A view along the length, a side view perpendicular to the length and a side view perpendicular to the length of an embodiment of a shield according to the invention are shown in Fig. 5a, Fig. 5b and Fig. 6, respectively. The side wall of the shield comprises a channel for the passage of a cooling fluid. The channel comprises an inlet (29a), an outlet (29c) and a helical section (29b) in the side wall extending from the channel inlet (29a) to the channel outlet (29c). The channel may be provided within a distance of the jet inlet equal to at most 50% of the length of the shield (Fig. 5a and Fig. 5b). Alternatively and preferentially, the channel may be provided within a distance of the nozzle outlet equal to at most 50% of the length of the shield (Fig. 6). Furthermore, the shield comprises a plurality of layers of flow disrupting elements (28). These layers are spaced apart in the length direction. Each element may have a surface that is at an angle of at least 20° and at most 70°, preferably at least 30° and at most 60°, with the length direction, thereby being configured to substantially deflect the flow direction and allow mixing of the gas and / or plasma and / or afterglow components within the shield. The layers may be provided within a distance of the nozzle outlet that is at most equal to 50% of the length of the shield (FIG. 5a and FIG. 5b). Alternatively and preferentially, the layers may be provided within a distance of the jet inlet that is at most equal to 50% of the length of the shield (FIG. 6). Thus, the cooling mechanism and the homogenizing means may be provided in the same part of the shield or in different parts of the shield.

[0081] Example 5: Powder Coating FIG. 7 is a cross-sectional view of an apparatus having a shield according to the present invention, which is particularly preferred for plasma coating of powders.

[0082] An inert gas can be provided to the inlet (40) of the guiding system in a predetermined flow. Powder (41) can be added, for example, by a Venturi injector (42). The resulting powder beam is then guided to a coating device (44) having a first plasma jet generator (45a) and a second plasma jet generator (45b) to which an aerosol containing an inert gas and a precursor is provided (46a, 46b). A shield (47) is removably attached to the jet outlets of both plasma jet generators (45a, 45b) by two adapters (48a, 48b), whereby the jet inlets (49a, 49b) of the shield are in communication with the jet outlets of the plasma jet generators. The powder beam flows through the plasma from the object inlet edge, which is circumferentially congruent with the powder beam, along a longitudinal direction (50) and continues to be exposed to the plasma over a certain length (51) to allow the coating of individual powder particles. The beam exits the shield through an article exit edge that is circumferentially congruent with the powder beam and is then collected in a collector system (52), e.g., a cyclone, for extracting the coated powder (54) from the inert gas (53). The coated powder can be returned to the inlet (40) for further coating cycles.

[0083] Example 6: Fiber Coating FIG. 8 is a cross-sectional view of an apparatus with a shield according to the invention, which is particularly preferred for plasma coating of textiles.

[0084] This configuration is similar to that of Example 5. A fiber (55) is passed through a coating device (44) having a first plasma jet generator (45a) and a second plasma jet generator (45b) to which an aerosol containing an inert gas and a precursor is provided (46a, 46b). A shield (47) is removably attached to the jet outlets of both plasma jet generators (45a, 45b) by two adapters (48a, 48b), whereby the jet inlets (49a, 49b) of the shield are in communication with the jet outlets of the plasma jet generators. The fiber extends through the plasma along a longitudinal direction (56) from an object inlet edge (57) circumferentially congruent with the fiber and remains exposed to the plasma for a certain length (51). The fiber exits the shield through an object outlet edge (58) circumferentially congruent with the fiber. The coated powder can be returned to the inlet (57) for further coating cycles.

[0085] Example 7: Spin Coating FIG. 9 is a perspective view of a shield according to the invention, with edges manufactured to be congruent with an axially symmetrical object in particular.

[0086] The shield (60) is especially manufactured to process an axially symmetric object (61) with a radial profile (62). Thereby, the shield (60) comprises a jet inlet (63) and a nozzle outlet with an edge (64) that is congruent with the radial profile (62). During exposure of the surface of the object to the plasma, the object is rotated (65) about its central axis (66). The shield may have a flange near the jet inlet for easy and removable attachment to the jet outlet of the plasma jet generating device, as seen for example in the previous embodiment or as more clearly shown in Figs. 1A-5B. Note that in Fig. 9, the surface of the object may be slightly inset into the edge (64) to minimize the gap between the object and the shield.

[0087] The shield (60) may be provided with an identification means, e.g. RFID, preferably located near the jet inlet (63) so that it can be easily read with a corresponding identification means reader module, such as an RFID reader module that may be provided on or near the plasma jet generating device. The device may thereby be configured to read the identification means on the shield before starting the method for treating the object and to hold the process or at least provide a warning message if it is determined that the identification means does not correspond to the nozzle outlet edge required for treatment by the intended method. For example, the intended method may be selected in particular to treat objects having a cylindrical shape, thereby requiring for example a straight nozzle outlet edge, and the inserted shield may have a slightly inclined or curved nozzle outlet edge, perhaps difficult for the operator to see. The device may then recognize from the identification means of the shield that an incorrect shield has been fitted and therefore the process must be held until the operator replaces this shield with the correct one.

Claims

1. 1. A method for plasma coating an object having an object contour, comprising: a. providing a replaceable shield (2), said replaceable shield comprising a jet inlet (22), a nozzle outlet (24), and a sidewall (21) extending from said jet inlet to said nozzle outlet, said nozzle outlet comprising an edge (25) that is essentially congruent with at least a portion of said object contour, whereby said shield comprises an identification means, said method further comprising: b. removably attaching the replaceable shield to a jet outlet of a plasma jet generating device; c. minimizing a gap between the nozzle outlet and the object by placing the object at the nozzle outlet such that the object contour fits snugly against the nozzle outlet edge to within a distance of at least 0.1 mm and at most 5 mm; d. plasma coating the object with a low temperature oxygen-free plasma at an operating pressure greater than atmospheric pressure, the plasma coating being performed by providing a plasma jet within the shield with the plasma jet generating device and injecting a coating precursor into the plasma jet within the shield, thereby creating the operating pressure; Thereby, plasma coating the object in an oxygen-deficient plasma zone; The method comprises: The method includes the additional step of identifying the provided shield prior to providing the plasma jet.

2. The method of claim 1 , wherein the plasma is coated in step d) at a temperature below 120° C.

3. 3. The method according to claim 1 or 2, wherein the shield is removably attached to the jet outlet by an adapter (3), the adapter being configured to removably mount the shield onto the plasma jet generating device, thereby communicatively coupling the jet outlet of the plasma jet generating device and the jet inlet of the shield.

4. 4. The method according to claim 1, wherein for plasma coating a plurality of types of objects, each type of object having a different object contour, step a is performed for each type of object, thereby producing a plurality of interchangeable shields, each shield comprising a nozzle outlet having a nozzle outlet edge that is essentially congruent with at least a portion of the object contour of a respective one of said each type of object.

5. Step d is A method according to any one of claims 1 to 4, comprising moving a surface of the object and the nozzle outlet relative to one another to deposit a coating on the surface.

6. 1. An apparatus for depositing a coating on an object having an object contour by means of an atmospheric pressure plasma jet, comprising: A plasma jet generating device (1) having a jet outlet (12); a nozzle comprising an adapter (3) and an exchangeable shield (2), said exchangeable shield comprising a jet inlet (22), a nozzle outlet (24) and a side wall (21) extending from said jet inlet to said nozzle outlet, said nozzle outlet comprising an edge (25) essentially congruent with at least a portion of said object contour, whereby said shield comprises an identification means; the adapter is configured to removably mount the shield onto the plasma jet generating device, thereby communicatively coupling the jet outlet and the jet inlet; The apparatus comprises an identification means reader module for reading the identification means associated with the nozzle outlet edge.

7. 7. Apparatus according to claim 6, comprising a transport means for in-line processing of planar or non-planar surfaces of continuous substrates, whereby the apparatus is configured to maintain each portion of the edge of the nozzle outlet at a distance of at least 0.1 mm and at most 5 mm of the surface of the substrate.

8. 8. Apparatus according to claim 6 or 7, wherein the identification means of the shield comprises an identification tag.

9. Apparatus according to any one of claims 6 to 8, wherein the identification means comprises an RFID.

10. 10. Apparatus according to any one of claims 6 to 9, wherein the replaceable shield comprises a flange (26) attached to the side wall (21) at the jet inlet (22), and the adapter comprises a retaining wall (31) with an opening (32) having a size and shape adapted to retain the flange.

11. Apparatus according to any one of claims 6 to 10, wherein the nozzle outlet of the shield is provided with a non-planar edge (25''').

12. Apparatus according to any one of claims 6 to 11, wherein the side wall of the shield comprises at least one precursor inlet (27).

13. The apparatus of any one of claims 6 to 12, wherein the shield comprises plastic.

14. A kit for carrying out the method according to any one of claims 1 to 5 and / or for constructing the apparatus according to any one of claims 6 to 13, comprising a plurality of interchangeable shields (2), each of said plurality of interchangeable shields comprising a jet inlet (22), a nozzle outlet (24) and a side wall (21) extending from said jet inlet to said nozzle outlet, said nozzle outlet comprising an edge (25) essentially congruent with at least a portion of the object contour, whereby said shield comprises an identification means, said kit further comprising a plasma jet generating device to which each of said plurality of shields can be attached.

15. 15. The kit of claim 14, wherein the identification means is associated with the nozzle outlet edge.

16. 16. The kit according to claim 14 or 15, further comprising an adapter (3) configured to removably mount at least one of the shields on a plasma jet generating device, thereby communicatively coupling a jet outlet of the plasma jet generating device with the jet inlet of a shield mounted on the plasma jet generating device.

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