Coating installation for coating a substrate in the form of a strip, method for coating both sides of a substrate in the form of a strip, and use

Abstract

The invention relates to a coating installation (1) for coating a substrate, which is in the form of a strip (2) and has a first strip surface (3) and a second strip surface (4), by means of a PVD coating process. The coating installation (1) comprises: - a coating chamber (5) having a chamber inlet (6) and a chamber outlet (7) along a conveying path (12), - a first PVD coating device (13), - a second PVD coating device (14), - optionally transport rollers (8), (9), (10), (11). The substrate is coated with coating material (15, 16) and, in one embodiment, is partially enclosed along a longitudinal section (L) by an edge enclosure (17). A central control unit (19) may be used for control purposes. The invention also relates to a method and to a use.

Description

[0001] CK

[0002] Coating system for coating a substrate formed as a strip, method for coating both sides of a substrate formed as a strip, and use

[0003] The invention relates to a coating system for coating a substrate formed as a ribbon. The invention further relates to a method for coating both sides of a substrate formed as a ribbon. A use is also described.

[0004] For coating strips, especially metallic strips such as steel strips, processes based on the principle of so-called vapor deposition can be used. The production of coatings using vapor deposition is also known as physical vapor deposition, or PVD for short.

[0005] The principle of vapor deposition involves providing a starting material and bringing it into the gas phase. The components of the material present in the gas phase, particularly atoms and / or ions, move within a deposition chamber and are directed towards a specific area where the coating is to take place, subsequently referred to as the deposition zone. The ribbon is transported through the deposition zone, causing the components of the material present in the gas phase to deposit onto the ribbon to be coated, thereby forming a coating.

[0006] One advantage of vapor deposition (VPD) is that it allows for the cost-effective production of coatings whose properties can be precisely controlled across a wide range of parameters. Another advantage is its suitability for coating many different materials. Unlike some other processes, VPD is particularly well-suited for producing coatings with high-melting-point materials or with materials in metastable phases.

[0007] Based on known variants of PVD coating, there is often a desire to be able to rely on a high degree of flexibility when coating substrates.

[0008] The problem is solved by a coating system for coating a substrate formed as a strip, having the features of claim 1. The problem is further solved by a method having the features of claim 15 and by a use having the features of claim 19.

[0009] A coating system for coating a substrate in the form of a strip is presented. The coating system is particularly suitable for coating a metallic strip, for example, a steel strip. The coating is carried out using a physical vapor deposition (PVD) coating process. The strip to be coated has a first surface and a second surface.

[0010] The coating system comprises a coating chamber with a chamber inlet and a chamber outlet. The strip to be coated is fed into the chamber inlet, through the chamber, and out of the chamber outlet. The coating chamber is, in particular, a largely enclosed chamber in which a technical vacuum can preferably be maintained, for example, between 10 ( -3 )The pressure is between 100 mbar and 100 mbar, preferably less than 20 mbar. Within the coating chamber, transport means are provided that are suitable for moving the belt along a conveying path through the coating chamber. This preferably achieves continuous conveyance of the belt through the chamber. The conveying path within the chamber can, for example, be in a plane. Alternatively, the conveying path within the chamber can also include one or more deflections of the belt, which are implemented, for example, by means of deflection rollers.

[0011] A first PVD coating device is arranged within the coating chamber. The first PVD coating device is positioned on one side of the conveying path to provide coating material for the continuous coating of the first strip surface. For this purpose, a first coating material is brought into the gas phase within the first PVD coating device and emitted towards the first strip surface, so that the first strip surface is continuously coated as the strip travels along the conveying path.

[0012] Similarly, a second PVD coating unit is arranged in the coating chamber. This unit is located on the opposite side of the conveyor path, meaning that a belt transported within the system passes between the first and second PVD coating units. The second PVD coating unit is thus positioned on the other side of the conveyor path and, due to this arrangement, serves to provide a second coating material in gaseous form, which is emitted towards the second belt surface. The second coating material in gaseous form exits the second PVD coating unit, reaches the belt at the second belt surface, and condenses on it. This continuously coats the second belt surface as the belt travels along the conveyor path.

[0013] Throughout this description, the terms "gas phase" and "evaporation" are used as they are commonly employed in the field of gas-phase deposition technologies. The term "gas phase" implies that a small fraction by weight, for example, up to 30% by weight, preferably not more than 10% by weight, of the material present in the gas phase is not in the gas phase in the strictly physical sense, but instead exists as vapor, aerosol, and / or clusters. The term "evaporation" implies that, depending on the material and technology used, the transition of particles into the gas phase occurs, at least partially, through mechanisms other than evaporation in the strictly physical sense, for example, by sublimation.In the context of usage in the field of gas phase deposition, and thus within the scope of the present description, the term evaporation therefore includes not only evaporation in the strictly physical sense, i.e., a transition to liquid.

[0014]

[0015] Gas phase, also other mechanisms, such as sublimation in particular. Likewise, the material existing in the gas phase is also synonymously referred to as material vapor.

[0016] The first and second PVD coating devices could be identical. However, it is equally conceivable that the first PVD coating device uses a different evaporation mechanism than the second PVD coating device.

[0017] By providing a coating system for the continuous coating of a strip with two PVD coating devices, one PVD coating device for the PVD coating of the first strip surface and one PVD coating device for the PVD coating of the second strip surface, it is advantageously achieved that a double-sided coating can be applied to a strip with high time efficiency.

[0018] According to an advantageous further development, it is provided that the first PVD coating device and the second PVD coating device can be operated simultaneously.

[0019] This is achieved, for example, by providing each of the two PVD coating devices with a sufficient power supply. Optionally, both PVD coating devices can be connected to the same control device, allowing the coating of both strip surfaces to be carried out simultaneously and centrally controlled.

[0020] According to an advantageous embodiment, the first PVD coating device and the second PVD coating device are positioned opposite each other. Preferably, one or both PVD coating devices are oriented with their gas outlet opening to perpendicularly apply material in the gas phase to the strip surface. This allows the coating of the second strip surface to occur simultaneously at the same position along the strip's length. Positioning the PVD coating devices opposite each other, with the strip transported between them, offers the advantage that the installation space required for the coating system can be made comparatively small.According to an alternative embodiment, the first PVD coating device and the second PVD coating device are positioned offset from each other in the direction of belt transport. This means that at a given position along the belt's length, one of the two belt surfaces is initially coated by one of the two PVD coating devices, and the other belt surface at the same position is subsequently coated after the belt has been transported to the point where it is exposed to gaseous material from the other PVD device. This design offers the advantage that the coating of the surfaces at a given point along the belt occurs at different times.This allows for more flexible adjustment of the coating of the strip, for example, a setting or control or regulation so that the strip temperature can be specifically set differently when coated by the second PVD coating device than when coated by the first PVD coating device.

[0021] For example, the second PVD coating device can be positioned at a distance of between 0.5 m and 100 m, preferably between 1 m and 40 m, and particularly preferably between 5 m and 20 m, behind the first PVD coating device, viewed in the direction of belt transport. Preferably, the second PVD coating device is positioned at a distance of 2 to 20 times the roller diameter of the belt system behind the first PVD coating device, which is the smallest of the available roller diameters. This minimizes the overall system length and allows for the integration of necessary components for temperature adjustment of the belt, such as cooling rollers with sufficient belt wrap. Preferably, one or both PVD coating devices are oriented with their gas outlet opening to vertically impregnate the belt surface with material in the gas phase.

[0022] According to an advantageous embodiment, the coating system comprises at least one edge shading device. The at least one edge shading device has, along a longitudinal section of the conveying path, a first edge enclosure for enclosing a first strip edge and / or a second edge enclosure for enclosing a second strip edge during its transport along the conveying path.

[0023] The development of the coating system according to the invention and its further developments has led to the surprising finding that, when coating the first strip surface with the first PVD coating device, coating material was deposited in the edge region of the second strip surface. These deposits are presumably a result of diffusion effects. Deposits of this kind are undesirable because they cause an overlap of the desired layer with particles from the opposing PVD coating device in the edge region. This leads to inhomogeneities in the layer thickness distribution and adhesion problems, both with similar and different coating materials.If the first PVD coating device and the second PVD coating device operate with different coating materials, these problems are compounded by the additional problem of potential changes in the properties of the coating due to the mixing of different materials.

[0024] With the described further development, according to which the first and / or second strip edge is enclosed, it was observed that effects such as the suspected diffusion, which caused a deterioration of the properties of the applied coating due to coating material condensing in the edge area from the additional PVD coating device located beyond the surface under consideration, were surprisingly effectively prevented. This resulted in a design that allows for double-sided coating of the strip in a continuous process. This improvement is also suitable for double-sided coating where both sides are coated with different materials, even if this occurs in the same process or even simultaneously.

[0025] According to a first further development, the edge enclosure has a U-shaped or an L-shaped cross-section. Alternatively or additionally, the second edge enclosure has a U-shaped or an L-shaped cross-section. Choosing an L-shaped cross-section results in shading of an edge area on one of the two belt surfaces; choosing a U-shaped cross-section results in shading of an edge area on both belt surfaces.

[0026] For example, the coating system may be equipped with two opposing PVD coating units for simultaneously coating the same position along the longitudinal extent of the strip. In this case, within one coating area of ​​the two opposing PVD coating units, the first edge enclosure and the second edge enclosure each have a U-shaped cross-section. The coating area can encompass the entire region of the strip still exposed to material vapor. Along the longitudinal extent of this entire region, both edges of the strip are fitted with the U-shaped edge enclosure to prevent diffusion of coating material in the edge area.The strip covered from the edge can, for example, have a width of up to 50 mm, 40 mm, 30 mm, 20 mm, or 10 mm, with the specific width being selected professionally in each individual case according to the respective requirements for layer quality and the prevailing operating conditions. The distance of the edge-covering section of the edge enclosure from the belt surface must also be determined professionally; the smaller the distance, the more effective the shading, but it must be sufficiently large to ensure smooth belt transport. The distance can, for example, be between 0.5 mm and 20 mm on one or both sides, preferably between 1 mm and 10 mm.

[0027] In an alternative embodiment, the strip coating system is equipped with a first PVD coating device and a second PVD coating device positioned offset from each other in the strip transport direction, such that a given position along the longitudinal extent of the strip is coated first on the first strip surface and then on the second strip surface. In particular, it can be provided that one or both of the two PVD coating devices emit the material in the gas phase with a main emission direction perpendicular to the strip surface being coated. For example, the second PVD coating device can be positioned at a distance of between 0.5 m and 100 m, preferably between 1 m and 40 m, and most preferably between 5 m and 20 m, behind the first PVD coating device in the strip transport direction.Preferably, the second PVD coating device is positioned at a distance of 2 to 20 times the roller diameter of the conveyor system behind the first PVD coating device, which is the smallest roller diameter of the available roller diameters.

[0028] According to this further development, a first edge-shading device is arranged in a coating area of ​​the first PVD coating device. The coating area of ​​the first PVD coating device is, in particular, the longitudinal section of the conveying path that is still reached to a technically relevant extent by coating material emitted by the first PVD coating device. The first edge-shading device has a first edge enclosure and a second edge enclosure, wherein the first edge enclosure and the second edge enclosure of the first edge-shading device are each provided with an L-shaped cross-section.The L-shaped cross-sections of the first and second edge enclosures of the first edge shading device each have a surface section that is oriented parallel or substantially parallel to the strip surface during strip transport and is positioned on the side of the second strip surface facing away from the first PVD coating device, overlapping an edge section of the second strip surface. Substantially parallel orientation can be understood, for example, as a deviation of up to + / - 30 degrees, but no more, from the parallel. The first edge enclosure is intended for placement on one of the two edges of the strip, and the second edge enclosure is intended for placement on the other of the two edges of the strip.For example, the first edge enclosure protects the left edge of the belt when viewed in the direction of belt transport, and the second edge enclosure protects the right edge of the belt when viewed in the direction of belt transport.

[0029] This means that the shading effect for blocking the material from the first PVD coating device is achieved by creating an overlap between the "foot" of the L-section and the second strip surface. It has been shown that this approach sufficiently protects the second strip surface from developing coating material originating from the first PVD coating device at its edge. The provision of an edge enclosure with an L-section thus ensures shading of the opposite strip surface. The strip surface facing the first PVD coating device, and which is intended to be coated by it, is not, however, shaded by the edge enclosure with the L-section.This offers the additional advantage over the use of an edge enclosure with a U-shaped cross-section that the side intended for coating can be completely coated up to its strip edge, thus eliminating the need for subsequent trimming of the strip edge.

[0030] Alternatively or additionally, a second edge-shading device is arranged in a coating area of ​​the second PVD coating device, analogous to the procedure described above. The second edge-shading device has a first edge enclosure with an L-shaped cross-section. It also has a second edge enclosure with an L-shaped cross-section. The L-shaped cross-sections of the first and second edge enclosures each have a surface section parallel or substantially parallel to the strip surface, positioned on the side of the first strip surface facing away from the second PVD coating device and overlapping an edge section of the first strip surface.The strip of the belt covered from the edge, i.e., the edge section that overlaps with the surface section of the respective edge enclosure, can, for example, have a width of up to 50 mm, up to 40 mm, up to 30 mm, up to 20 mm, or up to 10 mm. The width must be professionally selected in each specific case according to the applicable layer quality requirements and the prevailing operating conditions. The distance of the edge-covering section of the edge enclosure from the belt surface must also be professionally determined; the smaller the distance, the more effective the shading, but it must be sufficiently large to ensure smooth belt transport. The distance can be, for example, between 0.5 mm and 20 mm on one or both sides, preferably between 1 mm and 10 mm.

[0031] According to a preferred embodiment, one or more of the edge enclosures, particularly preferably all of them, are heatable. This can be implemented, for example, by making the edge enclosures from inductively heatable metal and arranging a heating device designed as an induction heating device in the coating system for inductively heating the respective edge enclosures. Alternatively, heating devices designed as radiant heaters, for example infrared heaters, can be arranged in the coating system to heat one or all of the edge enclosures.

[0032] For example, each edge enclosure in the system can be equipped with a heating device for warming that specific edge enclosure. Heating the edge enclosures ensures their usability over extended periods, as it effectively prevents any negative impact on the quality of the coatings produced on the belt by preventing the build-up of deposits on the edge enclosures that would otherwise occur over time.

[0033] Furthermore, according to a further development, it can be provided that one or more of the edge enclosures, or all of them, are arranged to be movable perpendicular to the belt transport direction in order to adapt the edge enclosure to different belt widths, preferably in a controlled manner. This can be achieved by positioning the edge enclosures, for example manually or by sensor-assisted control, in a direction parallel to the belt surface and perpendicular to the belt transport direction to a currently existing edge position.

[0034] According to a preferred embodiment of the coating system, an extraction device is arranged in the coating chamber. This device serves to extract coating material that moves laterally past the belt. For example, it can be provided that, viewed in the direction of movement of the coating material, an extraction device is arranged behind the moving belt and adjacent to one or both belt edges. Such an extraction device reduces the amount of coating material diffusing around the belt edge, thereby creating an effective measure for improving the coating quality in the edge sections of the respective reverse surface. The extraction can be provided alone or in conjunction with other measures to prevent contamination of the surrounding belt side.

[0035] In a particularly preferred embodiment, the coating system includes a heating device for heating the strip. Heating the strip often leads to improved coating quality because it promotes the formation of the coating from the condensing coating material, for example by encouraging diffusion processes on the strip surface.

[0036] It is particularly preferred that the first coating material and the second coating material are different materials. This means that in the first PVD coating device, a first coating material is present as the starting material and is brought into the gas phase, and in the second PVD coating device, a second coating material is present as the starting material and is brought into the gas phase. The first coating material and the second coating material are, as mentioned, different materials.

[0037] For example, the first coating material could be a metal, such as nickel, and the second coating material a metal, such as zinc. Alternatively, the first coating material could be a ceramic and the second coating material a ceramic. Another alternative, for example, could be a ceramic and the second coating material a metal. Other combinations of materials are also conceivable.

[0038] Examples of suitable PVD coating devices for the first and second PVD coating devices include the following types:

[0039] - Thermal evaporation device,

[0040] - Electron beam evaporator,

[0041] - Laser beam vaporizer,

[0042] - Arc vaporizer,

[0043] - Molecular beam epitaxy device,

[0044] - Cathode atomizer ,

[0045] - jet vapor deposition device,

[0046] - Steam injection device.

[0047] This means that in a preferred further development, the first PVD coating device corresponds to a first type selected from the list, and the second PVD coating device is either of the same type or corresponds to a second type selected from the list.

[0048] Preferably, one of the two PVD coating devices is a jet vapor deposition device; preferably, both PVD coating devices are jet vapor deposition devices.

[0049] The term jet vapor deposition device refers to a device in which the coating material is thermally vaporized, for example in a crucible, and then transported to the substrate—typically in a gas stream together with a carrier gas stream of inert gas, but in some embodiments also as a gas stream consisting solely of the vaporized material—preferably at a gas stream velocity above the speed of sound, particularly preferably above 500 m / s. The operating principle is described, for example, in the review article in the Handbook of Deposition Technologies for Films and Coatings (Third Edition), Science, Applications and Technology, 2010, pages 881–901.

[0050] https: / / doi.org / 10.1016 / B978-0-8155-2031-3.00018-1 (linked on the registration date) highlights .

[0051] The surface to be coated is typically located in an atmosphere that is lower than the atmosphere prevailing in the crucible. For example, the surface to be coated is located in a technical vacuum, preferably with a pressure of less than 100 mbar, for example between 10 ( -3 ) mbar and 20 mbar, which in large-scale implementation is a good compromise between good coating properties and the effort required to create and maintain the vacuum.

[0052] The JVD process demonstrates its advantages particularly in the large-area coating of strip, especially metallic strip such as steel strip. One advantage of JVD is that, due to the comparatively high overpressure relative to the interior of the coating chamber, which directs the material in the gas phase towards the surface to be coated, a coating rate of the strip is possible. This results in the advantage of cost-effective strip coating, especially when using correspondingly high strip speeds.

[0053] Preferably, one of the two PVD coating devices is a vapor spray device; more preferably, both PVD coating devices are vapor spray devices. A vapor spray device is a device for gas-phase deposition of the material, which is designed with an evaporation section comprising a pre-evaporation section and a post-evaporation section, preferably designed as a crucible. The pre-evaporation section has a spray head for preparing the coating material as the starting material and an injector tube. The injector tube is designed to direct the coating material prepared in the spray head to the post-evaporation section and to introduce the prepared coating material into the post-evaporation section in order to convert it into the gas phase there.

[0054] Preferably, the spray head is a wire syringe for arc melting and / or arc vaporization of the starting material introduced into the wire syringe. The material used to form the respective coating is, for example, in wire or strip form. The starting material is brought into the influence of an electric arc, preferably consisting of two wires or two strips of the starting material, one of which is connected as the cathode and one as the anode to a DC voltage source, and a voltage sufficient to form an arc is set using the DC voltage source.The material, melted and / or vaporized by the energy of the electric arc, flows through an inlet into the interior of a chamber, the so-called crucible, heated to a temperature at least equal to the vaporization temperature of the material used for coating or the material with the highest vaporization temperature. The material(s) in the crucible vaporize completely and exit through an opening in the crucible. The vaporized material(s) then impact the surface of the component, the strip material, or the workpiece to be coated, forming the respective coating.

[0055] The post-evaporation section is preferably followed by a nozzle section coupled to it, which has the nozzle outlet and ends with it.

[0056] In a special case where correspondingly high exit velocities of the material exiting the post-evaporation section are achieved, this alternative design form can be considered a variant of the JVD.

[0057] A further aspect of the present invention, which is described both as a supplement to and an alternative to the considerations already presented, is a method for coating both sides of a substrate formed as a ribbon using a physical vapor deposition (PVD) coating process. The ribbon has a first ribbon surface and a second ribbon surface. The following steps are preferably carried out:

[0058] a) A band is provided. For example, it is a metallic band, such as a steel band.

[0059] b) The belt is fed into a chamber inlet of a coating chamber of the coating system and transported through the coating chamber along a conveying path. During transport, the belt passes a first PVD coating device, which is positioned on one side of the conveying path, to continuously coat it with a first coating material in the gas phase from this PVD coating device. Similarly, it passes a second PVD coating device, which is positioned on the other side of the conveying path. The second PVD coating device serves to supply coating material for coating the second belt surface with a second coating material brought into the gas phase in the second PVD coating device.The first and second PVD coating devices can be positioned opposite each other, so that the coating of both strip surfaces occurs simultaneously. Alternatively, the second PVD coating device can be positioned offset from the first PVD coating device in the strip transport direction, so that first the first strip surface is coated with material from the first PVD coating device and then the second strip surface is coated with material from the second PVD coating device.

[0060] Once the belt has passed through the chamber, it is exited from the chamber outlet of the coating chamber.

[0061] In a further development of the process, after the double-sided coated strip has been exited from a chamber outlet of the coating chamber, the strip is trimmed by one edge section or trimmed by both edge sections, that is: an edge section that is either no longer homogeneously coated and / or that is contaminated with impurities from the rear-mounted PVD coating device and / or that is not completely coated due to an existing edge shading device is removed, for example by cutting.

[0062] This approach requires that the bandwidth is wider than the width of a coating area of ​​both the first PVD coating device and the second PVD coating device.

[0063] In a preferred embodiment of the method, the first PVD coating device and the second PVD coating device are positioned offset from each other in the direction of belt transport, for example between 0.5 m and 100 m. Preferably, the distance is 2 to 20 times the minimum roll diameter of the belt system, for example, a distance between 1 m and 40 m, particularly when the minimum roll diameter is 0.5 m to 2 m, such that the belt passes the first PVD coating device before the second PVD coating device. A distance between 5 m and 20 m is particularly preferred. Thus, a given belt position first reaches the first coating area of ​​the first PVD coating device, and the first belt surface is coated in this area.During further transport through the coating chamber, the same given strip position, according to the offset positioning of the second PVD coating device, reaches the second coating area of ​​the second PVD coating device at a later time, and in this area the second strip surface is then coated.

[0064] The first coating material and the second coating material are different materials, so the first and second strip surfaces are coated with different materials. The first coating material has a higher melting point than the second coating material. The strip is heated to a strip temperature TI for passing through the first PVD coating device, where TI is between 0.6 Ts and 0.8 Ts, preferably between 0.7 Ts and 0.75 Ts. Ts is the melting point of the first coating material in Kelvin. The temperature is set, controlled, and / or regulated so that the strip maintains this temperature within the first coating area. The coating can then be deposited by applying the first coating material at a temperature advantageous for coating formation.Heating the strip within the specified temperature range ensures good homogeneity of the layer thickness and a closed, virtually defect-free coating. The proposed process involves heating based on the melting point of the material and setting a lower temperature before passing through the second coating area. This is because the second coating material is selected as the one with the lower melting point of the two. In the second coating area, the strip then has a temperature of T2, and the other strip surface is coated with the second coating material, which has a lower temperature (achieved through cooling) compared to the strip temperature T1.This cooling preferably takes place in the intermediate section provided for this purpose and described above, which is, for example, between 0.5 m and 100 m in length, and particularly preferably 2 to 20 times the minimum roll diameter of the strip system, which can, for example, have a length of 1 m to 40 m. Preferably, the intermediate section is between 1 m and 40 m long, and particularly preferably between 5 m and 20 m. It is particularly preferred that the temperature is set such that the strip has reached a strip temperature T2 when passing the second PVD coating device, where T2 is between 0.6 Ts2 and 0.8 Ts2, preferably between 0.7 Ts2 and 0.75 Ts2, where Ts2 is the melting temperature of the second coating material in Kelvin.This advantageously ensures that the coating material of the two coating materials, which melts at a lower temperature, is not negatively affected in a subsequent vapor deposition step due to the substrate temperature being too high for the resulting coating. This prevents, for example, the coating material from being negatively affected in its properties, melted / remelted, or even partially or completely evaporated again. Cooling is preferably assisted by a cooling device arranged between the first PVD coating device and the second PVD coating device. This cooling device can, for example, be designed as a cooling roller that is fluid-cooled and in contact with the strip to be cooled. A cooling fluid, such as water, can be used as the cooling fluid.

[0065] In preferred further development, Ts is at least Ts2 + 100 K, so Ts > TS2 + 100 K, especially preferred Ts > Ts2 + 200 K, even more preferred Ts > TS2 + 300 K, in particular even more preferred Ts > TS2 + 500 K, and even more preferred Ts > TS2 + 800 K.

[0066] For example, the first coating material may be nickel and the second coating material zinc. An embodiment of the process with a cooling device designed as a cooling roller is particularly effective when a rough vacuum is present in the coating chamber, i.e., for example, with a pressure of 10 mbar or more, for example, between 10 mbar and 100 mbar, preferably between 10 mbar and 50 mbar. With a rough vacuum where the pressure in the chamber is within the aforementioned range, i.e., does not become too low, it is ensured that a cooling roller can achieve a sufficiently high cooling capacity, since there are enough particles in the atmosphere of the coating chamber to guarantee heat transfer.

[0067] In order to ensure good coating quality in the aforementioned pressure ranges, i.e., at a pressure of 10 mbar or more, for example between 10 mbar and 100 mbar, preferably between 10 mbar and 50 mbar, the first PVD coating device and / or the second PVD coating device is preferably designed as a PCD coating device whose coating mechanisms are based on the emission of coating material as particles with a comparatively high velocity of the emitted coating materials; in particular, the first PVD coating device and / or the second PVD coating device is / are designed as a jet vapor deposition device or as a vapor spray device, as has been explained in more detail earlier in this text.

[0068] Heating can be achieved, for example, using radiant heaters, such as infrared radiant heaters.

[0069] Alternatively or additionally, inductive heating of the strip can be carried out, for example. Alternatively or additionally, other types of temperature control can be implemented.

[0070] In a particularly advantageous embodiment of the method, the temperature T2 is set, starting from the temperature TI, also or exclusively by cooling the strip, that is, particularly preferably: without heating the strip by means of an apparatus in a region of the strip that has left the first coating area. This can be achieved in particular by adjusting the strip speed such that, starting from the temperature TI it has when passing the first PVD coating device, the strip has reached the desired temperature T2 when passing the second PVD coating device. This means, for example, that the strip speed is set to be slower the lower the temperature T2 is at a given temperature TI.This approach has the advantage that equipment for heating the strip only needs to be installed upstream of the first PVD coating unit, while the desired temperature for coating the other surface can be set by the second PVD coating unit without any further equipment for heating the strip. The required speed can be set, for example, based on empirically obtained data. Alternatively, it can be controlled or regulated based on in-situ sensor measurements of the strip temperature in the vicinity of the second PVD coating unit, i.e., at a strip position up to 10 cm, 50 cm, or 2 m upstream of the second PVD coating unit (in each case, measured in the direction of strip transport).A pyrometer, for example, can be provided as a sensor, arranged inside or outside the coating chamber and pointing towards the strip surface.

[0071] In carrying out the process, the coating system of the type mentioned above, or one of its further developments, can be used. In particular, the process control can be adapted using the corresponding elements of the coating system. Such a process control offers advantages analogous to those associated with the coating system itself.

[0072] Finally, it is proposed to use a coating system according to the invention, or one of its further developments, for the production of a strip that serves as a precursor for a double-sided coated sheet for electrochemical applications. In particular, the following electrochemical applications are included:

[0073] - Bipolar plate for fuel cells or

[0074] Electrolysis cells,

[0075] - Electrodes of batteries or accumulators with an anode coating, for example made of Zn or a Zn-based alloy, on the second strip surface and a cathode coating, for example made of Ni or a Ni-based alloy, on the first strip surface.

[0076] With the described coating system and its further developments, a strip can be advantageously produced from which a sheet can be cut for use in the aforementioned purposes. The described possibility of double-sided coating, and in further developments, double-sided coating with different materials, is particularly advantageous for the aforementioned application, allowing for the highly efficient production of the aforementioned sheets.

[0077] Further details, features and advantages of the subject matter of the invention will become apparent from the following description in conjunction with the drawings, in which exemplary embodiments of the invention are shown.

[0078] It goes without saying that the features mentioned above and explained below can be used not only in the combination specified, but also in other combinations or on their own.

[0079] They show:

[0080] Fig. 1 : Schematic representation of a first embodiment of a coating system in side view ;

[0081] Fig. 2 : schematic representation of a second embodiment of a coating system in side view ;

[0082] Fig. 3a) -c) : Detailed views of exemplary embodiments of a further development of a coating system from Fig. 1 or Fig. 2 ;

[0083] Fig. 4 : Layer thickness profile of a PVD coating .

[0084] Fig. 1 shows a schematic representation of a coating system 1, which is designed for coating a substrate 2, formed as a strip, with a first strip surface 3 and a second strip surface 4. The coating system has a coating chamber 5. A chamber inlet 6 is arranged on the coating chamber 5 for introducing the strip 2 into the chamber 5. The chamber inlet 6 and / or the chamber outlet 7, also shown, can, for example, be designed as part of a sluice gate. The strip 2 is transported through the coating chamber 5 along a conveying path, represented in Fig. 1 by arrow 12, using suitable conveying means, which are, for example, designed as transport rollers 8, 9, 10, 11.During the transport of the belt 2 through the coating chamber 5, the belt 2 is coated and then, as a coated belt, is led out of the chamber 5 through a chamber outlet arranged at the chamber 5.

[0085] Within chamber 5, a first PVD coating device 13 and a second PVD coating device 14 are arranged. The first PVD coating device 13 is positioned on one side of the conveying path to provide gaseous coating material 15 for the continuous coating of the first strip surface 3. The second PVD coating device 14 is positioned on the other side of the conveying path to provide gaseous coating material 16 for the continuous coating of the second strip surface 4. The two PVD coating devices 13 and 14 can be operated simultaneously, so that the strip is coated on both sides after being conveyed through the operated coating device. For simultaneous control, the two PVD coating devices 13 and 14 are connected to a central control unit 19.The first PVD coating device 13 and the second PVD coating device 14 are positioned opposite each other. Furthermore, both are oriented with their nozzle outlets perpendicular to the strip surface to be coated. This arrangement ensures that the strip 2, guided by the coating system 1 shown in Fig. 1, is coated simultaneously on both of its strip surfaces 3, 4.

[0086] The coating system 1 has an edge shading device. In the embodiment shown, this is designed as an assembly consisting of a first edge enclosure 17 for enclosing a first edge of the strip 2 and a second edge enclosure (not shown in this illustration due to the chosen perspective) for enclosing a second edge of the strip 2 along a longitudinal section L of the conveying path. The first edge enclosure and the second edge enclosure each have a U-shaped cross-section, meaning that they shade both an edge section of the first strip surface 3 opposite the first PVD coating device 13 and an edge section of the second strip surface 3 opposite the second PVD coating device 14 with a surface section parallel or substantially parallel to the strip surface.

[0087] Fig. 2 shows a schematic representation of a coating system 1, which is similar in its basic structure to the coating system shown in Fig. 1. In contrast to the coating system shown in Fig. 1, the first PVD coating device 13 and the second PVD coating device 14 are positioned offset from each other in the belt transport direction 12. Furthermore, both are oriented with their nozzle outlets perpendicular to the belt surface to be coated, so that the coating material, which is in the gas phase and emitted from the respective nozzle outlet, strikes the belt surface perpendicularly on average. This arrangement ensures that the coating material, as shown in Fig.In the coating system 2 shown, the guided belt 2 is first coated by the first coating material from the first PVD coating device 13, which is deposited on the first belt surface 3, and only afterwards by the second coating material from the second PVD coating device 14, which is deposited on the second belt surface 4.

[0088] Due to the offset positioning of the PVD coating devices, the coating system of Fig. 2 not only has a first edge shading device with edge housing 17 and a further edge housing on the opposite edge, but also a further, second edge shading device, which is arranged in the coating area of ​​the second PVD coating device. This second edge shading device comprises edge housing 18 and the further edge housing present on the opposite edge of the strip, which is not visible in the illustration due to the chosen perspective. The second edge shading device is explained in more detail in Fig. 3b).

[0089] Fig. 3a) shows a section through strip 2 and part of the strip coating unit of Fig. 1. The section runs perpendicular to the plane of the paper in Fig. 1. In Fig. 3a), the strip transport direction points perpendicularly into the plane of the paper. Around the left edge of the strip, a first edge enclosure 17 is visible in cross-sectional profile, which is a U-profile. This enclosure shades an edge section on each of the two strip surfaces relative to the normal on the strip surface. This can be seen at the extent Al, which denotes the width of the edge section that is shaded along the length L shown in Fig. 1 relative to the second PVD coating unit 14. On the other side, the surface is shaded relative to the first PVD coating unit, which is not shown in Fig. 3a). The second strip edge is shaded analogously by the second edge enclosure 17'.

[0090] Figure 3b shows a shading solution used in the coating system of Figure 2. In the coating system of Figure 2, the first PVD coating device 13 and the second PVD coating device 14 are positioned offset from each other in the belt transport direction 12.

[0091] In the coating area of ​​the second PVD coating device 14, that is, the area in which the arrival of coating material emitted from the second PVD coating device 14 is observed, a second edge shading device is arranged. This comprises a first edge enclosure 18 of the second edge shading device with an L-shaped cross-section and a second edge enclosure 18' of the second edge shading device with an L-shaped cross-section. The L-shaped cross-section is characterized in that the edge enclosure has only one surface section in each case that is oriented parallel to the strip surface or substantially parallel to the strip surface in order to shade an edge section from the PVD coating device.It can be seen that this surface section is arranged on the side of the strip surface that faces away from the area where the PVD coating device emits coating material in the gas phase. This is because the L-shaped surface section, which is intended to create shading by being arranged parallel or substantially parallel to the strip surface, is meant to block diffusing particles that, due to diffusion, would cause an undesirable partial coating of the side of the strip that, from the perspective of the PVD coating device, represents the reverse side. It has been shown that an arrangement of an edge enclosure with an L-shaped cross-sectional profile, as shown in Fig. 3b, can largely prevent contamination of the respective reverse side.Since this procedure is carried out analogously in the respective coating area of ​​each of the two PVD coating devices, each with reversed signs, it is achieved that each of the two strip surfaces can be completely coated by one of the two PVD coating devices, thereby avoiding contamination of the respective back side as a result of unwanted diffusion processes.

[0092] Figure 3c) shows an extraction device comprising a first extraction nozzle 19 and a second extraction nozzle 20. As can be seen in Figure 3c), each of the two extraction nozzles, when viewed in the direction of movement of the coating material, is positioned behind the moving belt and at one of the two belt edges. The extraction nozzles serve to extract coating material moving laterally past the belt.

[0093] Fig. 4 shows a layer thickness profile of a PVD coating of Zn material, applied using a system similar to that shown in Fig. 1, but without an edge-shading device. A jet vapor deposition coating was used as the PVD mechanism. The layer thickness profile was determined by X-ray fluorescence spectroscopy. This layer thickness profile demonstrates that points PI and P2 represent positions with a largely homogeneous layer thickness. Furthermore, the width of the strip covers the entire width of the coating area, so no contamination of the reverse side is expected. Therefore, it is recommended that after the double-sided coated strip is exited from one chamber outlet of the coating chamber, the strip be trimmed around both edges.

Claims

CK patent claims 1. Coating system (1) for coating a substrate formed as a strip (2), in particular a metallic strip, for example a steel strip, by means of a physical vapor deposition coating process, in short: PVD coating process, wherein the strip has a first strip surface (3) and a second strip surface (4), and wherein the coating system (1) comprises: - a coating chamber ( 5 ) with a chamber inlet ( 6 ) and a chamber outlet ( 7 ) for transporting the belt ( 2 ) through the coating chamber ( 5 ) along a conveying path ( 12 ) , - a first PVD coating device (13) positioned on a first side of the conveying path for providing coating material for the continuous coating of the first belt surface (3) with first coating material brought into gas phase in the first PVD coating device (13) during the transport of the belt (2) along the conveying path (12) , - a second PVD coating device (14) positioned on a second side of the conveying path (12) for providing coating material for coating the second belt surface (4) with second coating material brought into gas phase in the second PVD coating device (14) during the transport of the belt (2) along the conveying path.

2. Coating system (1) according to claim 1, characterized in that the first PVD coating device (13) and the second PVD coating device (14) can be operated simultaneously.

3. Coating system (1) according to one of the preceding claims, characterized in that the first PVD coating device (13) and the second PVD coating device (14) are positioned opposite each other.

4. Coating system ( 1 ) according to claim 1 or according to claim 2, characterized in that the first PVD coating device ( 13) and the second PVD coating device ( 14 ) are positioned offset from each other in the direction of belt transport.

5. Coating system ( 1 ) according to one of the preceding claims, characterized in that, that the coating system ( 1 ) has at least one edge shading device, wherein at least one edge shading device along a longitudinal section (L) of the conveying path ( 12 ) comprises a first edge enclosure ( 18 ) for the enclosure of a first belt edge and / or a second edge enclosure for the enclosure of a second belt edge of the belt (2 ) during its transport along the conveying path ( 12 ).

6. Coating system ( 1 ) according to claim 5, wherein the first edge enclosure ( 18 ) has a U-shaped or an L-shaped cross-section, and / or the second edge enclosure has a U-shaped or an L-shaped cross-section.

7. Coating system ( 1 ) according to claim 5 or according to claim 6, wherein in a coating area ( 15, 16) of two opposing PVD coating systems the first edge enclosure has a U-shaped cross-section and the second edge enclosure has a U-shaped cross-section.

8. Coating system ( 1 ) according to one of claims 5 to 7, wherein with the first PVD coating device (13) and second PVD coating device (14) positioned offset from each other in the direction of belt transport a first edge shading device is arranged in a coating area (15) of the first PVD coating device (13), wherein the first edge shading device has a first edge enclosure (17) of the first edge shading device with an L-shaped cross-section and a second edge enclosure (17') of the first edge shading device with an L-shaped cross-section, wherein the L-shaped cross-sections of the first edge enclosure (17) and the second edge enclosure of the first edge shading device each have a surface section parallel or substantially parallel to the strip surface during strip transport, which is positioned on the side of the second strip surface (4) facing away from the first PVD coating device (13) and in overlap with an edge section of the second strip surface (4).and / or a second edge shading device is arranged in a coating area (16) of the second PVD coating device (14), wherein the second edge shading device has a first edge enclosure (18) of the second edge shading device with an L-shaped cross-section and a second edge enclosure (18') of the second edge shading device with an L-shaped cross-section, wherein the L-shaped cross-sections of the first edge enclosure (18) and the second edge enclosure (18') of the second edge shading device each have a surface section parallel or substantially parallel to the strip surface during strip transport, which is positioned on the side of the first strip surface facing away from the second PVD coating device (14) and in overlap with an edge section of the first strip surface.

9. Coating system ( 1 ) according to one of claims 5 to 8, characterized in that one of the edge enclosures or several of the edge enclosures or all edge enclosures are heatable.

10. Coating system ( 1 ) according to one of claims 5 to 9, characterized in that one or more of the edge enclosures or all edge enclosures are arranged to be movable perpendicular to the belt transport direction in order to adapt the edge enclosure to different belt widths, preferably in order to control the adaptation of the edge enclosure to different belt widths.

11. Coating system ( 1 ) according to one of the preceding claims, characterized in that an extraction device ( 19, 20 ) is arranged in the coating chamber (5) for extracting coating material moving laterally past the belt (2 ).

12. Coating system ( 1 ) according to one of the preceding claims, characterized in that the coating system ( 1 ) has a heating device for heating the strip .

13. Coating system ( 1 ) according to one of the preceding claims, characterized in that the first coating material and the second coating material are different materials.

14. Coating system ( 1 ) according to one of the preceding claims, characterized in that the first PVD coating device ( 13) and / or the second PVD coating device ( 14 ) is designed as one of the following: - Thermal evaporation device, - Electron beam evaporator, - Laser beam vaporizer, - Arc vaporizer, - Molecular beam epitaxy device, - Cathode atomizer , - jet vapor deposition device, - Steam injection device.

15. Method for coating both sides of a substrate formed as a strip (2) by means of a physical vapor deposition coating process, or PVD coating process for short, wherein the strip (2) has a first strip surface (3) and a second strip surface (4), preferably with a coating system (1) according to one of the preceding claims, wherein the following steps are carried out: a) Providing the tape (2 ) , b) Inserting the belt (2 ) into a chamber inlet ( 6) of a coating chamber (5) of the coating system ( 1 ), transporting the belt (2 ) through the coating chamber (5) along a conveying path ( 12 ), passing a first PVD coating device ( 13 ) positioned on a first side of the conveying path ( 12 ) for providing coating material for the continuous coating of the first belt surface (3) with first coating material ( 15) brought into the gas phase in the first PVD coating device ( 13) during the transport of the belt (2 ) along the conveying path ( 12 ) and at a second PVD coating device ( 14 ),which is positioned on a second side of the conveying path ( 12 ) to provide coating material for coating the second strip surface (4 ) with second coating material ( 16) brought into the gas phase in the second PVD coating device ( 14 ) during the transport of the strip (2 ) along the conveying path ( 12 ), exiting the double-sided coated strip from a chamber outlet (7 ) of the coating chamber (5 ).

16. Method according to claim 15, characterized in that the first PVD coating device ( 13) and the second PVD coating device ( 14 ) are operated simultaneously.

17. Method according to claim 15 or according to claim 16, wherein after the double-sided coated strip is exited from a chamber outlet (7) of the coating chamber (5) the strip (2) is trimmed by one edge section or is trimmed by both edge sections.

18. Method according to any one of claims 15 to 17, wherein the first PVD coating device ( 13) and the second PVD coating device ( 14 ) are positioned offset from each other in the direction of belt transport, wherein the belt (2 ) passes the first PVD coating device ( 13) in front of the second PVD coating device ( 14 ), wherein the first coating material and the second coating material are different materials, wherein the first coating material has a melting temperature Ts which is higher than a melting temperature Ts2 of the second coating material, wherein the strip is heated to a strip temperature between 0.6 Ts and 0.8 Ts for passing through the first PVD coating device.

19. Method according to claim 18, wherein the strip is allowed to cool down after passing through the first PVD coating device (13) for passing through the second PVD coating device (14), optionally supported by cooling by means of a cooling device arranged between the first PVD coating device (13) and the second PVD coating device (14), for example a cooling device designed as a fluid-cooled cooling roller, until it has a strip temperature between 0.6 Ts2 and 0.8 Ts2.

20. Use of a coating system according to one of claims 1 to 14 for the production of a strip as a precursor for a double-sided coated sheet for electrochemical applications, in particular: - Bipolar plate for fuel cells or Electrolysis cells, - Electrodes of batteries or accumulators with a cathode coating, for example made of Ni or a Ni-based alloy, on the first strip surface and an anode coating, for example made of Zn or a Zn-based alloy, on the second strip surface .

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