Patent Publication Number: US-2007114132-A1

Title: Device and method for separating metals and/or metal alloys from metallo-organic electrolytes

Description:
The invention relates to a device and process for depositing metals and/or metal alloys from metal-organic electrolytes, in particular metal-organic complex salts in organic solvents, onto products and having at least one coating section for coating the products, at least one additional processing section, and at least one sluice chamber for sluicing the products into and out of the device essentially without oxygen and/or moisture penetrating.  
      A galvanic deposition of aluminum, magnesium, and their alloys from aqueous systems, as is customary in classical galvanotechnology, is not possible due to the very low potential of these elements. Although in the past decades there have been numerous approaches to depositing aluminum, magnesium, and their alloys from non-aqueous systems, only deposition from complexes containing aluminum or magnesium alkyls were successful on the industrial scale. Therein, electrolyte variants with correspondingly suitable process control and analytics have been used for the most varied applications with more or less success. In several cases large-scale industrial application has become possible therewith.  
      The metal alkyls used in the production of the individual electrolyte variants react, as is known, very vigorously with oxygen and water to form reaction products, such as, for example, alkoxy compounds or aluminum oxanes. These reaction products are no longer in the position to form additional complexes with the alkali metals or alkali halides used in the electrolyte formulas. They remain behind as soluble contaminants in the electrolyte and in so doing reduce its electrical conductivity. Likewise, the maximum usable current density is reduced with increasing concentration of these reaction products, whereby the coating process loses its cost-effectiveness and, in given cases, its good quality.  
      The aforementioned constellation of problems has already been investigated in a study at the Georg Simon Ohm Technical Institute in Nuremberg in 1987, with the result that the penetration of oxygen and/or moisture into a coating system in which there are alkyl-based metal-organic electrolytes should be largely avoided in order to ensure a long service lifetime of the electrolytes and optimal layer quality. Independently of the chemical or electrochemical disadvantages caused by the penetration of oxygen and water into the coating system, avoiding the penetration of oxygen and/or water into the coating system is also markedly important with regard to the reliable and safe operation of such a system, above all in regard to reliability in processing and safety in production and with regard to the environment.  
      In the state of the art various coating systems are known which also include in part approaches for avoiding the penetration of oxygen and/or moisture into parts of the coating system. Such a system, in which an electrolytic coating of metallic or non-metallic endless products with metals or alloys from aprotic water and oxygen-free electrolytes is provided in a continuous process, is described in DE 197 16 493 C2. For this purpose rinsing and drying processes are attached, which are intended to remove the residues of aqueous solutions. In addition to this, exiting of the coated endless products from the system via a sluice system is provided. The sluice chamber comprises a central chamber with a sealing liquid which represents a barrier for the air contained in an outer chamber. A third chamber contains an inert gas. In addition to this, regeneration circuits are provided in which all the liquids used in the processes are prepared, cleaned, and recycled.  
      From DE 30 23 827 C2, sealed to the outside, a tubular cell is known through which the material which is to be treated and which is contacted by cathodes can be moved in the axial direction, in particular continuously, along anodes. In order to prevent the undesired escape of the electrolyte from the tubular cell as well as to prevent the penetration of an air atmosphere into it, the tubular cell can be pressurized with a protective gas. According to this publication a sluice arrangement consisting of several chambers is also provided into which inert gas and/or an inert liquid can be introduced for mutual sealing of the individual chambers.  
      According to DE 199 32 524 C1, for the purpose of an electrochemical treatment, in particular for electrochemical coating of parts which are conductive or made conductive, these parts are brought into a container filled with electrolyte solution or into a rotating basket which is rotated during the treatment and thus coats all around the parts. The container is sealed gas-tight. The treatment of the parts in the basket is done without any reloading. The respective liquids or solutions are merely pumped into the container and out of it once again. For drying, the container is centrifuged each time and in so doing the residues of the electrolyte solution are centrifuged off by propelling the basket. Due to its design this system is not suitable for depositing metal-organic electrolytes.  
      Also From DE 41 18 416 A1 a device for coating parts, which are preferably relatively thin, is known, in which device a coating is done by bringing the parts into containers disposed so as to be adjacent to one another. In so doing, the containers or baths are in an inert gas atmosphere. In addition to this, a rinsing bath, an etching bath, and a depositing bath are provided. In arranging the various baths in a common container, sluices formed as partitions are provided which can be penetrated by the parts to be treated. For this, the penetrable partition is formed in a penetration area by a pair of rollers which are made of an elastic material, rotate around an axis, run against one another in such a manner that a tight seal is formed, and slide opposite the bordering walls of the container in such a manner that a tight seal is formed.  
      From these aforementioned publications devices only follow which attempt to avoid any penetration of oxygen or moisture into the device in partial areas of the respective devices. For this, merely parts of the devices are provided with, for example, rinsing and drying devices or a three-part sluice chamber.  
      The objective of the present invention is thus to provide a device and a process for depositing metals and/or metal alloys from metal-organic electrolytes in which safety-related problems no longer occur, and any emission of solvent from the device, and in particular any reaction of electrolyte systems used with oxygen and moisture from the ambient atmosphere of the device, can be avoided, essentially completely.  
      The objective is realized in a device according to the preamble of claim  1  by the fact that at least one siphon rinsing device with a separating device for gas-related separation of the other sections of the device from, or sealing of, these other sections with respect to the coating section and at least one hood component which can be flooded with inert gas and essentially tightly encloses the coating section, the at least one siphon rinsing device, and the at least one additional coating section are provided. For a process according to the preamble of claim  17  the objective is realized by the fact that an essentially solvent loss-free sluicing of the products through at least one sluice chamber into a device for depositing metals and/or metal alloys is provided, the products are transferred to at least one coating section essentially excluding gas, the products are coated in the at least one coating section, the coated products are transferred from the coating section to at least one output section essentially excluding gas via at least one siphon rinsing device, and the finished products are sluiced out via at least one additional sluice chamber, where an inert gas atmosphere bell is held up over all the sections of the device. Extensions of the invention are defined in the subordinate claims.  
      Thereby a device and a process for depositing metals and/or metal alloys are provided with which it is possible to reduce any carry-over of oxygen and water or moisture as well as other contaminants into the coating electrolyte in so far as possible. Thereby a long service lifetime of the coating electrolyte can be ensured. The formation of undesired reaction products, like solvent emissions, can be very sharply restricted or essentially completely prevented. A diffusion barrier for oxygen and moisture between these individual sections of the device is provided precisely by providing siphon rinsing devices with a separating device for separating the gas atmosphere into individual sections of the device and for sealing these individual sections of the device relative to one another. The gas atmosphere in the essentially tightly sealed hood component which encircles the individual sections of the device can be set so as to be optimal in each section of the device. Thereby it is also possible to prevent any migration of solvent into the electrolyte area via the gas atmosphere. Since it frequently happens that the coating electrolyte is chemically incompatible with cleaning fluids or other solvents, this separation of the gas atmospheres of the individual sections of the device has proven itself particularly advantageous. Thereby a safe and reliable operation of the system is possible. For one thing, by providing an essentially tightly sealing hood component an encapsulation of the entire atmosphere within the device, and thus a separation from the exterior atmosphere which surrounds the device, is possible. Thereby evaporating solvent can be collected before its exit from the device and recycled into the corresponding parts of the system. Contamination of the ambient air around the device can thus be essentially eliminated. For another thing, it is possible within the hood component to maintain a constant pressure which is at the same time different from that which would correspond to the pressure in the ambient atmosphere. Preferably, at least in a part of the individual sections of the hood component a slight overpressure with respect to the atmosphere which surrounds the device is maintained and monitored. Preferably, at least one pressure maintenance device for maintaining a constant pressure in the hood component and/or a slight overpressure in the hood component with respect to the outer and/or ambient atmosphere is provided. Unintentional penetration of the exterior atmosphere into the device and thus any contamination of the gas atmosphere within the device can thus be essentially avoided.  
      In order to be able to maintain an essentially constant pressure in the hood component, in particular in the individual hood sections, therefore in particular a slight overpressure with respect to the exterior atmosphere of the device, preferably at least one gas buffer device is provided and is connected, or can be connected, to it/them, in particular in the first and/or last section. Gas buffer devices of this type are thus preferably provided at the entrance and exit of the device since there variations in pressure can occur due to the sluicing in and sluicing out of the products. The gas buffer devices are filled if an overpressure outside of a preselectable tolerance occurs in the hood component and emptied if an underpressure outside of a preselectable tolerance occurs in the hood component, e.g. if gas atmosphere is withdrawn from the respective hood component as, for example, for flooding a sluice chamber with inert gas.  
      Preferably, at least one oxygen monitoring device is provided in the at least one sluice chamber and/or the sections of the hood component. Preferably, at least one device for monitoring the solvent concentration is also provided in the sluice chamber(s). Thereby it is possible to constantly monitor the oxygen and/or solvent content of the gas atmosphere in the individual sections of the device. Since the sluice chamber(s) serve to prevent the introduction of air or oxygen into the device, the oxygen content of the sluice chamber atmosphere is regularly monitored after the sluicing in of the products, the draining of the air introduced with the product in so doing, and the rinsing of the chamber with, for example, inert gas. If the sluice chamber is opened to the hood component, the oxygen content within the chamber should be as close to zero as possible so that any penetration of oxygen into the hood component as well as the other parts of the device can be avoided. The discharge of solvent from the device should also be reduced to as close to zero as possible. In order to be able to monitor the solvent content in the sluice chambers, which represent a connection of the device to the exterior atmosphere, devices for monitoring the solvent concentration are also provided there. To the extent that the oxygen and/or solvent content exceed(s) a threshold value which can be predetermined and/or set, or is set, it is possible to trigger an adaptation of the pumping times to the introduction of gas into and discharge of gas from the sluice chamber and/or an additional rinsing phase with an inert gas during pumping cycles to reduce the oxygen content in the at least one sluice chamber. For example, a longer pumping cycle for pumping out the contaminated gas atmosphere is provided. Also the inert gas atmosphere bell can be monitored with regard to its oxygen content, where the oxygen content should be as close to zero as possible. Through these measures it can be ensured in an optimal manner that the inert gas atmosphere bell of the device is contaminated with oxygen to hardly any degree, or not at all, where optimal coating results and a very high safety and reliability during the treatment of the products can be achieved.  
      Preferably, a cleaning and/or activation section for cleaning and/or pre-treating the surface of the products and/or at least one output section for sluicing the products out of the device are provided. Preferably, the at least one cleaning and/or activation section comprises one or more sealable treatment basins with a cleaning fluid for cleaning the products to be coated and/or an activation fluid for activating their surfaces or for producing an adhesion promoter layer. In such a cleaning and/or activation section cleaning of the raw products is advantageously possible, where an oxide-free and blank surface of the products can be produced. Thereby an optimal adhesive strength for the following coating can be ensured. In order to improve this adhesive strength still further, an adhesion promoter layer can advantageously be applied to the surface of the product in this section of the device. By providing sealable treatment basins it is possible to open them selectively when a respective product is supposed to be inserted into them. Undesired evaporation of treatment fluid into the hood atmosphere can thus be further suppressed.  
      Preferably, the at least one cleaning and/or activation section comprises at least one rinsing device disposed after the at least one treatment basin(s) for rinsing the pretreated products and preventing any carry-over of chemicals from the cleaning and/or activation section. Precisely when providing a siphon rinsing device following the cleaning and/or activation section, therefore before the coating section, is it logical to provide such a rinsing of the pretreated products in order to prevent any carry-over of the chemicals from the cleaning and/or activation section into the siphon rinsing device and thus subsequently into the coating electrolyte. Preferably, a solvent preparation and/or regeneration device is provided and connected to such a rinsing device. The cleaned solvent is in particular once again recycled into this siphon rinsing device, while the cleaned cleaning fluid or activation fluid or other fluid in the treatment basins disposed before this stage can be recycled into these treatment basins. For cleaning, distillation and subsequently storage of the cleaned solvent is provided.  
      Preferably, the at least one solvent preparation and/or regeneration device for the cleaning and/or activation section is provided in the bypass to it. Thereby a constant cleaning of the solvent and the electrolyte or other cleaning and bath fluids during the coating, or even during the pre-cleaning and also the subsequent treatment section, is possible.  
      Preferably, the at least one sluice chamber is also connected, or can be connected, to a solvent separation and recycling device and/or a gas oscillation system. Preferably, at least one sluice chamber is provided at the entrance of the cleaning and/or activation section and/or at least one sluice chamber is provided at the exit of the output section. Preferably, in the sluicing-in step the products are introduced into the at least one sluice chamber. In so doing, the sluice chamber is filled with the exterior atmosphere, sealed, and subsequently evacuated, therefore the exterior atmosphere is conveyed out of the chamber and it is subsequently flooded with inert gas. Thereafter in the sluicing-in step the products are introduced into a first treatment section of the device. In the sluicing-out step from the device these products are brought out of the hood atmosphere and into the sluice chamber, it is sealed, and the hood atmosphere pumped out of it and recycled into the hood section. The sluice chamber can subsequently be opened and the products taken out. Thereafter the sluice chamber is sealed once again, the penetrating exterior atmosphere drained, and the chamber flooded with inert gas. Particularly preferably, the pumped-out sluice atmosphere is prepared, where dry inert gas and cleaned solvent are recycled into the process, in particular dry inert gas into the inert gas atmosphere bell and cleaned solvent into a treatment basin. The gas oscillation system therefore includes the pumping of dry inert gas into the hood atmosphere after pumping the atmosphere of the sluice chamber out of the sluice chamber.  
      Therefore, since exterior atmosphere is brought in with the product to be coated during the sluicing into the sluice chamber preferably provided at the entrance to the device before the coating, and since after the products are coated they are once again brought out into the exterior atmosphere with the opening of a sluice chamber provided at the end of the device and penetration of exterior atmosphere into the sluice chamber, it has proven itself advantageous to provide a solvent separation and recycling device in the area of the sluice chamber. Precisely there, during sluicing in and sluicing out of the products, oxygen as well as moisture can penetrate into the device and evaporated solvent can escape from the device. Via preferably provided cooling devices, atmosphere pumped out of the sluice chamber and contaminated with solvent can thus be cooled and the solvent separated, collected, and recycled. In the solvent separation process the pumped-out gas is dried and can subsequently be recycled once again into the hood atmosphere. Through the solvent separation in the sluicing-out area the products can be cleaned of the solvent residues adhering to them and leave the device essentially completely dry so that solvent emissions essentially can no longer take place. Also, in the area of the sluicing out of the products, the solvent residues discharged during the pumping-out process are recondensed, collected, and subsequently recycled into the process, in particular into the last siphon rinsing device.  
      Preferably, the inert gas atmosphere bell is also cleaned, in particular by condensing the inert gas atmosphere and recycling the condensed-off solvent portions into their respective circuits, in particular treatment basins. Preferably, a cooling device with a condensate separation device is provided for the recovery of carried-over and/or evaporated solvent residues, in particular in the hood component and/or coating section and/or connected to the at least one sluicing chamber. Particularly preferably, the one or more cooling devices in the hood sections and/or in the hood component comprise solvent recycling devices for recycling solvents into treatment and/or coating basins and/or the at least one siphon rinsing device. Thereby it is also possible to remove solvent contaminants from the gas atmosphere in the hood component once again. The portions of solvent condensed into the cooling devices can subsequently be recycled into corresponding treatment basins of the respective hood section. Preferably, the respective cooling devices are provided in the individual hood sections since the evaporating liquids are usually each different in the individual hood sections so that the contaminants in the gas atmosphere are always different. Thus, recycling is advantageously done within the respective hood section.  
      Preferably, the at least one coating section comprises at least one coating basin which can be sealed to prevent uncontrolled evaporation of solvent into the hood component. In particular, at least one cooling device for condensing evaporated solvent and at least one collection device for collecting the condensed solvent are also provided in the gas space of the at least one coating basin. In addition to this, the at least one coating section can comprise at least one output rinsing device. After the coating process the products are put into the rinse bath provided in the output rinsing device in order to remove adhering electrolyte residues. To clean the rinsing bath recycling of cleaned solvent from the solvent separation and/or regeneration device is provided in particular.  
      Since the siphon rinsing device is provided for separating the individual sections of the device, therefore in particular of the cleaning and/or activation section, of the treatment section, and of the output section, it has proven itself advantageous to provide an essentially non-reactive solvent in these transition areas. The at least one siphon rinsing device is thus preferably filled with an inert solvent. Thereby undesired chemical reactions between mutually incompatible chemicals from the individual sections of the device can be essentially avoided. Preferably, the at least one siphon rinsing device comprises a sealable double rinsing device with a mounted partition which is oriented so that hood sections lying above are divided. By providing such a partition, which dips into the rinsing bath of the siphon device, a gas-tight separation of different hood sections of the device can be provided. In order to make possible the transport of products through the siphon rinsing device, specifically since a particular preferred transport device provided within the hood sections cannot penetrate the partition, in particular at least one transport device is disposed, or can be disposed, within the double rinsing device for traversing the products below the partition so that during the filling of the double rinsing device with a rinsing fluid the transport device is positioned below the level of the fluid. Thereby a complete immersion of the products into the rinsing fluid is ensured, whereby they can be rinsed all around and cleaned with the preferably inert rinsing fluid in order to avoid any carry-over of chemicals and/or gas atmosphere from a forward section into the following section of the device.  
      Preferably, in addition to this, at least one electrolyte/solvent separating device is provided in the area of the coating section. In particular the electrolyte/solvent separating device(s) comprise(s) a distillation device for distilling solvent from the electrolyte/solvent bath fluid drained from the at least one coating basin. In addition to this, devices for recycling the resulting clean solvent into the output rinsing basin and/or devices for recycling the electrolytes into the electrolyte circuit are provided.  
      Cleaning of the electrolyte solution, therefore of the coating solution, can thus be done in the bypass of the coating section. This cleaning device follows in particular the coating baths, where in particular clean solvent is recycled into the output rinsing basins disposed after the coating baths, and in particular electrolyte into the coating baths.  
      Electrolyte fluid and/or solvents are preferably conducted essentially in closed circuits. Thereby any contamination of the other baths of the device is essentially avoided. Advantageously, there is cleaning or preparation of electrolyte fluid and/or solvent and/or a rinsing fluid to avoid any carry-over of chemicals. To avoid any carry-over of electrolyte fluid adhering to the products and/or cleaning fluid and/or activation fluid, rinsings in the various rinsing devices are preferably provided in addition. These rinsing devices can be provided at various points of the device and of the coating process, in particular in the output area of the respective sections of the device.  
      Above all, products of any form can be coated with the devices according to the invention, therefore also products having back-cuts in which solvent can collect. Such collections cannot be removed with devices from the state of the art, on account of which a solvent coat cannot be reliably avoided with them. With the process according to the invention and the device according to the invention removal of solvent residues for products of any form is possible in a reliable manner. 
    
    
      For more detailed explanation of the invention an embodiment example is described in more detail with the aid of the drawing. It shows a comprehensive view of a device according to the invention for depositing metals.  
      The figure shows a schematic diagram as a comprehensive view of a device  1  for depositing metals and/or metal alloys. The device comprises a cleaning and/or activation section  2 , a coating section  3 , and an output section  4 . In addition to this, it has a hood component  5  which essentially tightly encloses all three aforementioned parts. The hood component is subdivided into three sections  50 ,  51   52 . The three hood sections are separated from one another by respective partitions  53 ,  54 .  
      The cleaning and/or activation section  2  comprises a first sluice chamber  20 , a first treatment basin  21 , a second treatment basin  22 , and a rinsing basin  23 . In addition to this, the cleaning and/or activation section comprises a part of a first siphon rinsing device  60 . The siphon rinsing device  60  is divided by the partition  53  into two parts so that it forms a double rinsing device, which is accessible from section  2  and section  3  but otherwise forms a diffusion barrier. All basins or rinsing devices can be sealed with individual covers  24 ,  25 ,  26 ,  27 ,  62 . The sluice chamber  20  comprises a sluice door  28  which makes possible the running of products into the sluice chamber. Preferably, such products are run into the sluice chamber via a transport carriage, which is not represented in the diagram.  
      The sluice chamber  20  is connected to a device  70  for the recovery of solvent and a gas oscillation system  80 . The device for recovery of the solvent has a cold trap  71 , a valve  72 , a condensate separation device  73 , as well as a line  74  between the valve  72  and the sluice chamber  20 , a line  75  between the cold trap  71  and the condensate separation device  73 , and a solvent recycling line  76  between the condensate separation device  73  and the first treatment basin  21 .  
      The gas oscillation system  80  comprises a vacuum pump  81  three valves  82 ,  83 ,  84 , and a line  85  between the sluice chamber  20  and the first valve  82 , an additional line  86  between the valve  82  and the vacuum pump  81 , a line  87  between the vacuum pump  81  and the valve  83  in the recycling line to the hood component as well as an additional line  88  between the valve  83  and the hood component  50 . The line  87  also leads to the valve  84  and from it an additional line  89  leads outwards into the exterior atmosphere. Through this, air can be blown out of the device.  
      In addition to this, a solvent preparation and/or regeneration device  90  is connected to the cleaning and/or activation section  2 . The solvent preparation and/or regeneration device comprises a distillation device  91  and a condensate collecting tank  92 . The distillation device is fed via a line  93  which comes from the rinsing basin  23 . Between the distillation device  91  and the condensate collecting tank  92 , a line  94  is also provided. The cleaning fluid cleaned in the distillation device  91  is recycled via a line  95 , a pump  96 , and an additional line  97  into the second treatment basin  22 . Clean solvent distilled off by the distillation device can be pumped back from the condensate collecting tank  92  to the rinsing basin  23  via a line  98 , a pump  99 , and a line  100 .  
      Between the rinsing basin  23  and the second treatment basin  22  an overflow line  29  is provided in addition to this in order, if necessary, to avoid an overflow of the rinsing basin in case an excess amount of solvent is recycled.  
      The excess solvent is then recycled into the second treatment basin  22  via the overflow line  29 .  
      In addition to this, the hood section  50  of the cleaning and/or activation section  2  comprises a transport device  55  for traversing products  7  between the individual treatment, rinsing, and other basins. For this, the transport device comprises a transport carriage  56  which is provided in the embodiment with a hook  57  for suspending the products  7  to be coated. Here the hook  57  can be traversed fastened on the transport carriage  56  so that the products on this hook can be slowly lowered into their respective baths and can be lifted out of them.  
      In addition to this, the hood section  50  comprises a cooling device  58 . It is represented in the figure in the form of a cooling coil. Via this cooling coil evaporated solvent can be condensed and collected in a collecting device  59  also provided in the hood section  50 . In the figure the collecting device is represented in the form of a collecting trough. The solvent collected in the collecting trough or collecting device  59  can be recycled to the first coating basin  21  via a drain line  101 . Thus there can be a recycling of solvent into the first as well as into the second coating basin. In principle, still more coating basins can also be provided but the figure here merely reproduces one possible embodiment. It is also possible to provide several rinsing basins. Likewise, it would be possible in principle to provide more than one sluice chamber.  
      In order to be able to maintain a uniform pressure within the hood section  50 , despite cleaning of the gases in this hood section and despite recycling of cleaned gases, a gas buffer container  120  is provided outside of the hood component  5 .  
      The gas buffer container  120  is connected to the interior of the hood section  50  via a line  121 . Via this line  121  there is a bilateral exchange of gas between the gas buffer container and the hood section  50 . Thereby it is possible to maintain a preset overpressure and above all a constant pressure within the hood section.  
      To check the oxygen and solvent content in the cleaning and/or activation section  2  one provides a first oxygen sensor  122  in the area of the hood section  50  as well as a second oxygen sensor  123  and a solvent concentration sensor  124  at the sluice chamber  20 . All the sensors can be connected to a monitoring and control device (not shown in the figure) in order to monitor an overshoot of the set threshold values and, if necessary, to selectively adapt pumping cycles of the sluice chamber and an exchange of gases.  
      The coating section  3  comprises the second part of the siphon rinsing device  60  which, as mentioned above, is formed as a double rinsing device. For the transport of the products brought through the cover  62  into the siphon rinsing device  60 , within the siphon rinsing device  60  a transport device  66  is provided which can comprise in particular a transport carriage, as is represented in the figure. After the transport through the siphon rinsing device the products can be taken out once again on the side of the coating section  3  through the cover  63  of the siphon rinsing device  60 . The coating section  3  comprises two coating basins  30 ,  31  as well as an output rinsing basin  32  and a first part of an additional siphon rinsing device  61 . Each of these basins is provided with covers  33 ,  34 ,  35  while the siphon rinsing device is provided with the cover  64  on the side of the coating section. In the gas space below the covers  33 ,  34  of the two coating basins  30 ,  31  cooling coils  36 ,  37  and collecting troughs  38 ,  39  are each provided in order to condense solvent which evaporates from the electrolyte during the coating and, in particular after the coating basins, to conduct it into the rinsing bath  32 .  
      Also, the coating section  3  is provided with a cleaning device connected to the coating basins in order to clean the electrolyte in the bypass in an electrolyte/solvent separation device  110 . Thereby it is ensured that no noteworthy amounts of electrolyte are carried over, whereby a substantially closed material circuit can be produced. To clean the electrolyte, fluid is conducted from the two coating basins  30 ,  31  to a distillation device  112  via lines  111 . In addition to this, a condensate collecting tank  113  is provided which is connected to the distillation device  112  via a line  114 . The cleaned electrolyte is recycled to the coating basin  30  via lines  115 ,  117  and a pump  116 . The solvent distilled from the electrolyte/solvent mixture is collected in the condensate collecting tank  113  and recycled to the rinsing bath in the output rinsing basin  32  via a line  118 , a pump  119 , and a recycling line  102 . Thus the rinsing bath in the output rinsing basin  32  is always provided with clean solvent. If the level in the output rinsing basin should rise too high, an overflow line  103  is provided between the output rinsing basin and the second coating basin  31 . Via this overflow line the excess rinsing fluid, therefore in particular solvent, runs back into the second coating basin.  
      Like the cleaning and/or activation section  2 , the coating section  3  also comprises a transport device  55  with a transport carriage  56  and a hook  57  in order to be able to transport the product  7  to be coated between the individual basins of the coating section. In addition to this, a cooling device  58  in the form of a cooling coil as well as a collecting trough as collecting device  59  for condensed solvent are also provided. Via a drain line  104  the collected condensed solvent is recycled to the first coating basin  30 .  
      The outlet section  4  comprises the second part of the siphon rinsing device  61 . This is, like the transport device  60 , provided with a transport device  67 . Via this, the products brought through the cover  64  into the siphon rinsing device are transported to the section lying on the other side of the partition  54  and having a cover  65  of the siphon rinsing device  61 . The transport is done, as in the siphon rinsing device  60 , below the surface of the rinsing fluid in the siphon rinsing device. Thereby an essentially complete exclusion of gas during transport of the products from the coating section into the output section is made possible.  
      In addition to this, the output section comprises a second sluice chamber  40  for sluicing the coated products out of the device. The sluice chamber is provided with a cover  41 . In addition to this, it comprises a sluice door  42 . Similarly to the sluice chamber  20  the sluice chamber  40  is also provided with a device  130  for the recovery of solvent and a gas oscillation system  140 . The device for the recovery of solvent is also provided with a cold trap  131 , a valve  132  between the sluice chamber  40  and the cold trap  131 , a condensate separation device  133 , a line  134  between the valve  132  and the sluice chamber  40 , a line  135  between the condensate separation device  133  and cold trap  131 , and a solvent recycling line  136  between the condensate separation device  133  and the siphon rinsing device  61 .  
      The gas oscillation system  140  comprises a vacuum pump  141 , three valves  142 ,  143 , and  144  as well as several lines located between them. A first line  145  leads from the sluice chamber  40  to the first valve  142 , a second line  146  leads from the valve  142  to the pump  141 . To it, a line from the cold trap  131  also leads, as is also the case for the device  70  between the cold trap  71  and the vacuum pump  81 . From the pump  141  a line  147  leads to the valve  143  and from it a recycling line  148  leads to the hood section  52 . From the vacuum pump the line  147  also leads to the valve  144 , via which, in particular, air from the sluice chamber  40  can be blown outwards into the environment via a line  149 .  
      The hood section  52  also comprises a transport device  55  with a transport carriage  56  which comprises a hook  57  in order to grasp products  7  and to be able to lower them into the individual basins. Likewise, cooling coils  58  are provided as a cooling device and a collecting trough  59  is provided for the condensed solvent which can be recycled from the collecting trough via a run-off line  105  to the siphon rinsing device  61 .  
      The output section  4  is also provided with a gas buffer container  125  and a line  126  between the interior of the hood section  52  and the gas buffer container  125 . With this it can be ensured that within the output section as constant a gas pressure as possible is maintained, although, for example, by recycling dry inert gas via the line  145  an overpressure in the hood section of the output section could occur, just as an underpressure during flooding of the sluice chamber  40  with hood atmosphere from the output section after the pumping out of the exterior atmosphere following a process of sluicing finished products out of the sluice chamber  40 .  
      Specifically because of the constant opening and closing of the output section for the sluicing out of finished products and recycling of purified gas, in order to determine, and if necessary to intervene to correct, the oxygen and solvent content within the output section in as continuous a manner as possible, and thus to avoid as much as possible any undesired solvent emission from the sluice chamber, and in order to keep the solvent loss and also hazardous exhaust gases from the device as low as possible, first and second oxygen sensors  127 ,  128 , and a solvent concentration sensor  129  are provided., The first oxygen sensor  127  is provided in the upper hood section  52  while the second oxygen sensor  128  and the solvent concentration sensor  129  are provided at the sluice chamber  40 . Also, the hood section  51  over the coating section  3  is provided with such an oxygen sensor  150 .  
      The course of a coating with the respective regeneration steps for electrolyte, cleaning fluid, solvent, and gas atmosphere will now be described in more detail.  
      A product to be coated is brought into the first sluice chamber  20  via the sluice door  28 . This is done in particular via a transport carriage, which is however not represented in the figure. During the process of sluicing in, the sluice chamber is inevitably filled with exterior atmosphere (air) and subsequently sealed. Thereafter the sluice chamber is evacuated via the vacuum pump  81  and the lines  85  and  86 . For this, the valve  82  is opened. Since then only uncontaminated air is in the sluice chamber, it can be discharged outwards directly via the line  89  and the opened valve  84 . Subsequently, the sluice chamber is flooded with inert gas from the hood section  50 . Thereupon the inner cover  24 , which is disposed between the sluice chamber and the hood section  50 , can be opened and the product brought into the inert gas atmosphere within the hood section  50 . The amount of oxygen which can penetrate into the first hood section  50  is very small since the sluice chamber can be evacuated up to a final pressure of less than 1 to 2 mbar and it is furthermore possible that intermediate rinsings with inert gas, in particular nitrogen and argon, are performed.  
      The amount of gas needed for the flooding, said gas being taken from the hood section  50 , would presumably lead to a lowering of the pressure unless the gas buffer container is provided. In order to avoid this and also to prevent new inert gas, e.g. nitrogen, constantly having to be brought into the hood section, in which in turn traces of oxygen and water can then be found, the gas buffer container  120  is connected to the hood section  50  which holds the pressure in the hood section  50  essentially constant due to the possible change in volume.  
      A monitoring of the atmosphere within the hood section can be done continuously by means of the oxygen sensors. The solvent concentration is monitored via the solvent concentration sensor  124 . Checking the oxygen diffusion into the system is logical, in particular with regard to the service lifetime of the electrolytes and the coating quality, but also with regard to the general reliability of processing and operational safety of the entire system.  
      After the product has been brought through the cover  24  into the hood section  50 , the cover  24  can be closed once again and the sluice atmosphere pumped out, where an inert gas/solvent mixture is present in the sluice atmosphere and pumped out. This is done after opening the valve  72  via the line  74 , whereby the inert gas/solvent mixture is conducted through the cold trap  71 . After the condensation the dry inert gas obtained is recycled via the vacuum pump  81 , the line  87 , the then open valve  83 , and the line  88  to the hood section  50 . The inert gas can once again be made available to the atmosphere in the hood section  50  as cleaned gas. The excess gas volume is collected by an increase in volume in the gas buffer container  120 , whereby the pressure in the hood section  50  can be held essentially constant.  
      The accumulating condensed solvent is introduced into the condensate separation device  73  via the line  75  and can be recycled to the first treatment basin  21  via the solvent recycling line  76 , in particular in a periodically recurring manner. Subsequently, the evacuated sluice chamber is once again flooded with fresh inert gas and the door to the exterior atmosphere, namely the sluice door  28 , can be opened once again in order to bring new products into the device.  
      Via the transport device  55  the products can be brought into the treatment basins  21 ,  22 , which in particular contain a cleaning fluid, and can be pre-cleaned there, and in particular a blank, oxide-free surface can be produced on them in order to ensure an optimal adhesive strength in the subsequent coating. In addition to this, an adhesion promoter layer can be applied there in this basin. In order to essentially avoid the evaporation of solvent, the covers  25 ,  26  are provided. Likewise, the cover  27  is provided on the rinsing basins which are each preferably only opened when goods or products are brought in or out. The rinsing basin  23  disposed behind this serves the purpose of avoiding any carry-over of chemicals from the treatments basins  21 ,  22  into the siphon rinsing device  60 , where also the carry-over into the coating electrolyte in the basins in the coating section should be avoided. The fluid of the rinsing basin  23  is regularly prepared via the solvent preparation and/or regeneration device  90  which is connected in the bypass to the cleaning and/or activation section.  
      After the rinsing of the pretreated product it is put into the siphon rinsing device  60  via the cover  62 . Due to the partition  53  being provided, the two hood sections  50  and  51  lying above are separated from one another in a gas-tight manner but are still connected to one another by the double rinsing basins of the siphon rinsing device  60  so that products can reach through. Preferably, the fluid in the siphon rinsing devices is identical to the solvent used in the coating electrolyte. In order to avoid any reaction with cleaning fluid and/or coating electrolyte as far as possible, an inert solvent is preferably used. By providing the siphon rinsing device between the activation section  2  and the coating section  3  the advantage results that in the cleaning fluids of the cleaning and activation section those solvents can also be used which are poorly compatible with the coating electrolyte since any migration of the solvent into the electrolyte area via the gas atmosphere is prevented. A carry-over of solvent with the products to be coated is in particular also most substantially prevented by the preparation of the fluid of the rinsing basin  23  via the distillation device  91 .  
      After lifting the products out through the cover  63  of the siphon rinsing device  60 , they arrive in the coating section  3  and therein can be lifted into the coating basins  30 ,  31 . Along with the two coating basins represented in the basins, numerous additional ones can be provided, likewise additional output rinsing basins  32 , where in the figure merely one of them is represented. In order to avoid uncontrolled evaporation of solvent in the hood section  51  lying above, the covers  63 ,  33 ,  34 ,  35 , and  64  are closed in normal operation. Preferably, the covers are only opened to run products into, or take products out of, the individual basins.  
      In the two coating basins  30 ,  31  the cooling coils  36 ,  37  and the collecting trough  38 ,  39  are each located in the gas space between the bath fluid level and the cover. Here solvent which is evaporated from the electrolyte during the coating is condensed and conducted to the rinsing bath in the output rinsing basin  32 . Via the distillation device provided in the electrolyte circuit rather large amounts of electrolyte are regularly brought into reaction and pumped back once again to the basin  30  via the lines provided therein as well as the pump  116 . The solvent distilled from the electrolyte is collected in the collecting tank  113  and recycled once again to the output rinsing basin  32  or to the rinsing bath contained therein via the lines and the pump  119 . To avoid an overflow of the output rinsing basin  32 , excess solvent is recycled into the circuit or the basin  31  via the overflow line  103 . Thereby it is ensured that no noteworthy amounts of electrolyte are carried over into the siphon rinsing device  61  disposed further on, where even at this point a substantially closed material circuit can already be produced.  
      The connecting siphon rinsing device  61  between the coating section and the output section is comparable in structure and function to the siphon rinsing device  60 . The products completely immersed therein are taken out once again through the cover  65  on the side of the output section  4 . Due to the previous rinsing in the output rinsing basin  32 , in which fresh solvent is contained, the electrolyte residues adhering previously from the coating section  3  are collected and not carried over into the output section  4 . In addition to this, each of the output rinsing basins also serves to effectively utilize, and remove from the system, excess process heat which arises in the coating process.  
      In the output section  4  the second sluice chamber  40  is also provided, into which the coated product is brought. This is done via the cover  41 . After stocking the sluice chamber with finally coated product, a pumping-off process is also initiated. This serves for the recovery of any solvent residues still adhering to the coated product. Thereby it is possible that the completely coated product leaves the device dry and solvent emissions essentially can take no longer place. All the solvent evaporated during the pumping off process, recondensed in the cold trap  131 , and collected in the condensate separation device  133  is recycled into the siphon rinsing device  61  via the line  136 . Otherwise, the sluicing-out process runs analogously to the sluicing-in process with regard to pumping in and pumping out of sluice atmosphere and inert gas. For sluicing out the sluice door  42  is opened.  
      The individual hood sections  50 ,  51 , and  52  are flooded with inert gas and, at least in the present embodiment example, held, via an automatic pressure maintenance system, constantly at a slight overpressure with respect to the ambient atmosphere. Thereby any penetration of air into the hood component is avoided. The oxygen sensors  122 ,  123 ,  127 ,  128 , and  150  continuously specify the oxygen content in the respective gas atmosphere. If an overshoot of predefined threshold values is detected, an adaptation, with respect to the pumps  81 ,  141 , of the pumping time is performed or an additional rinsing with inert gas during the pumping cycle in the sluice chambers  20 ,  40  is initiated.  
      Also, providing the siphon rinsing devices filled with a barrier fluid, in particular inert solvent, provides for an additional increase of the barrier effect in this area, in particular in combination with the covers  62 ,  63 , and  64 ,  65 , whereby an additional reduction of the diffusion of oxygen and moisture into the coating section  3  can be made possible. The combination of sluice chambers, a vacuum system, a gas oscillation system, and the siphon rinsing devices provides for a very long service lifetime of the metal-organic coating electrolytes and a uniform coating quality since the formation of undesired reaction products, such as, for example, alkoxy compounds or aluminum oxanes, can be effectively restricted or essentially prevented.  
      By providing a solvent preparation for the cleaning and/or activation section  2  any contamination of the coating electrolytes by oxygen and moisture as well as any carry-over of other chemicals can be effectively prevented, in particular also the carry-over of solvents used in the cleaning fluids which, in given cases, are incompatible with a certain coating electrolyte. By providing the solvent preparation and/or regeneration device  90  direct recycling of cleaning fluid and solvent into the corresponding circuit can be made possible. Thereby contamination in the rinsing basin  23  can also be held to a very low level.  
      By condensing the hood atmosphere in the hood sections  50 ,  51 ,  52  they can be kept as dry and pure as possible. Also, any condensation of solvent residues found on the goods which evaporate during the transport time, in particular when the products are still warm, can be condensed off in a controlled manner and recycled once again into the individual material circuits via the drain lines.  
      Along with the embodiment example described above and represented in the drawing, numerous others can be formed in each of which it is possible to hold solvent emissions from the device as low as possible and to achieve as high as possible a reduction of the carry-over of oxygen and moisture as well as other contaminants into a coating electrolyte and thus to clearly extend the service lifetime of coating electrolytes while avoiding the formation of undesired reaction products. In particular, only one, or more than the two, treatment basins, coating basins, siphon rinsing devices, and rinsing basins can also be provided. Also, additional sections, in particular additional coating sections, can be provided. Also, the siphon rinsing device(s) can be replaced by another device with corresponding action, where furthermore a gas-related separation between sections of the device is made possible. In principle, it is also possible to configure the cleaning and/or activation section to be smaller or, in given cases, to even have it omitted entirely. In any case, the devices comprise a closed hood atmosphere which forms an essentially tight bell over the individual stations of the coating device, where at the same time there is a constant cleaning of the atmosphere as well as the treatment or coating baths and rinsing baths. This can be accomplished in a particularly simply manner by leading the cleaning sections in the bypass to the respective processing or treatment sections. Alternatively, more complex cleaning steps or circuits are possible.  
     List of Reference Numbers  
     
         
           1  Device  
           2  Cleaning and activation section  
           3  Coating section  
           4  Output section  
           5  Hood component  
           7  Product  
           20  First sluice chamber  
           21  First treatment basin  
           22  Second treatment basin  
           23  Rinsing basin  
           24  Cover  
           25  Cover  
           26  Cover  
           27  Cover  
           28  Sluice door  
           29  Overflow line  
           30  First coating basin  
           31  Second coating basin  
           32  Output rinsing device  
           33  Cover  
           34  Cover  
           35  Cover  
           36  Cooling coil  
           37  Cooling coil  
           38  Collecting trough  
           39  Collecting trough  
           40  Second sluice chamber  
           41  Cover  
           42  Sluice door  
           50  First hood section  
           51  Second hood section  
           52  Third hood section  
           53  Partition  
           54  Partition  
           55  Transport device  
           56  Transport carriage  
           57  Hook  
           58  Cooling device  
           59  Collecting device  
           60  First siphon rinsing device  
           61  Second siphon rinsing device  
           62  Cover  
           63  Cover  
           64  Cover  
           65  Cover  
           66  Transport device  
           67  Transport device  
           70  Device for the recovery of solvent  
           71  Cold trap  
           72  Valve  
           73  Condensate separation device  
           74  Line  
           75  Line  
           76  Solvent recovery line  
           80  Gas oscillation system  
           81  Vacuum pump  
           82  Valve  
           83  Valve  
           84  Valve  
           85  Line  
           86  Line  
           87  Line  
           88  Line  
           89  Line  
           90  Solvent preparation and/or regeneration device  
           91  Distillation device  
           92  Condensate collection tank  
           93  Line  
           94  Line  
           95  Line  
           96  Pump  
           97  Line  
           98  Line  
           99  Pump  
           100  Line  
           101  Drain line  
           102  Recycling line  
           103  Overflow line  
           104  Drain line  
           105  Drain line  
           110  Electrolyte/solvent separation device  
           111  Line  
           112  Distillation device  
           113  Condensate collection tank  
           114  Line  
           115  Line  
           116  Pump  
           117  Line  
           118  Line  
           119  Pump  
           120  Gas buffer container  
           121  Line  
           122  First oxygen sensor  
           123  Second oxygen sensor  
           124  Solvent concentration sensor  
           125  Gas buffer container  
           126  Line  
           127  First oxygen sensor  
           128  Second oxygen sensor  
           129  Solvent concentration sensor  
           130  Device for the recovery of solvent  
           131  Cold trap  
           132  Valve  
           133  Condensate separation device  
           134  Line  
           135  Line  
           136  Solvent recycling line  
           140  Gas oscillation system  
           141  Vacuum pump  
           142  Valve  
           143  Valve  
           144  Valve  
           145  Line  
           146  Line  
           147  Line  
           148  Line  
           149  Line  
           150  Oxygen sensor