EP0075099B1 - Apparatus for electroplating metals, particularly aluminium - Google Patents

Abstract

An installation for electro-depositing metal, such as aluminum, on elongated goods such as tapes or wires characterized by a tubular cell, which is closed to the outside and provided with airlock arrangements at each end so that goods can be conveyed therethrough in contact with an electrolyte for electroplating. The cell is formed of a plurality of interconnected rectangular tubes with each tube having a flange at each end for forming a connection and receiving interchangeable nonconductive insert pieces, which match the interior dimensions of the tube and have atleast two longitudinal channels for guiding the goods to be metallized and for positioning anodes to surround the goods to be metallized in the flow of electrolyte.

Description

The invention relates to a system for the galvanic deposition of metals, in particular aluminum from aprotic, oxygen-free and water-free aluminum-organic electrolytes, on wire, tube or strip-shaped material with an externally closed tubular cell, through which the cathodically contacted material to be treated is treated is preferably continuously movable in the axial direction along anodes and through which the electrolyte can be pumped with the aid of a closed electrolyte circulation system against the direction of movement of the material, a lock arrangement being provided at each end of the tubular cell, which prevents the electrolyte from flowing out of the tubular cell consists of several chambers.

A system of this type for the deposition of metals, in particular precious metals, has become known from US Pat. No. 3,865,701. In this known system, the tube cell is closed at both ends by lock arrangements, but it cannot be prevented that atmospheric oxygen and air humidity come into contact with the electrolyte. Therefore, such a system for the electrodeposition of aluminum is not suitable, since an electrolyte must be used for aluminizing, which is produced under oxygen- and water-free conditions and must be kept as far as practically possible under these conditions.

However, in order to make such a system suitable for the galvanic deposition of aluminum, it is proposed in the older patent application EP-A-43440, which is considered to be state of the art according to Art. 54 (3) EPC, that the tubular cell which is sealed off from the outside has a Shielding gas (inert gas) is applied and that the individual chambers of the lock arrangements are sealed against each other by inert gas and / or inert liquid. Furthermore, for fading in and out and for redirecting the direction of movement of the flowing electrolyte between the tube cell and the lock arrangements, T-shaped connecting pieces are arranged which have a diaphragm which prevents the longitudinal passage of the electrolyte and which vertically deflects the electrolyte flow and which has a shape similar to the cross section of the treatment Good, tight-fitting breakthrough. To seal the individual chambers, it is proposed that at least one disk-shaped chamber wall has a radial bore leading to the opening for the passage of the material to be treated, which is connected to an inert liquid circuit via a connecting piece. Via this hole, the opening in the chamber wall can be supplied with inert liquid so that it practically forms a liquid lock through which the entry of atmospheric air is not possible, but also prevents the electrolyte from escaping. However, this principle can and is also used for washing the treated goods, it then being expedient that the inert liquid required for this is obtained from the electrolyte by distillation and that this inert liquid enriched with the electrolyte is then fed back into the electrolyte circuit.

Both in the electroplating system according to US Pat. No. 3,865,701 and in the system according to the older patent application EP-A-43440, tubular cells with a round cross section are used, the lock arrangements connected to both ends of the tubular cells also having a round profile in cross section. Both the tubular cells and the lock assemblies are made of plastic and require a very high manufacturing effort. In particular, the manufacture of the lock arrangement in the system according to US Pat. No. 3,865,701 is very complex, since the lock housing practically consists of one piece, while in the system according to the older patent application, the individual chambers of the lock arrangements consist of pipe pieces and disk-shaped chamber walls, which manufacturing a little easier.

The invention is based on the object. to make a system of the type described in the introduction simpler and more efficient, with the possibility being given that several strips can be coated at the same time without significant additional effort in order to achieve a higher throughput. There should also be the possibility that the material to be treated is only partially coated.

The system according to the invention is characterized in that the tubular cell consists of a plurality of preferably metallic square tubes which can be flanged together and in which interchangeable non-conductive inserts are arranged, which on the one hand are adapted to the clear width of the square tubes and on the other hand are shaped in such a way that they provide longitudinal grooves and channels for Management of the material to be aluminized, the anodes surrounding the material to be treated and the electrolyte. In this way, tube cells of any length can be produced with relatively simple means, and the individual sections can be dimensioned so that they are easily transportable. The inserts can be replaced relatively easily, so that the system is very flexible. The interchangeable insert pieces are preferably arranged opposite one another, the outer sides of which are adapted to the clear dimensions of the square tubes and on the opposite side of which recesses are provided for guiding and covering the material to be treated and the electrolyte and for holding the anodes surrounding the material to be treated. The normally external anodes are used also used moderately for shielding the electrolyte against the metallic inner wall of the square tube, it being advantageous that the recesses for the anodes are designed such that the inserts are supported on the anodes. A very simple assembly results from the fact that the inserts are firmly connected to the anodes in such a way that two inserts form a unit which can be pushed into the square tube.

Each of these units therefore also practically forms a square tube with flat end faces made of a non-conductive material. Their external dimensioning is such that they can be inserted exactly into the metallic sheathing tube. Each unit has at least the length of the corresponding square tube, it being expedient if several square tubes are combined to form a tube cell, the assembly being carried out so that the end face of a unit does not fall into the plane of the fastening flanges of the square tubes. In this way not only a better seal, but also a better centering of the individual insert pieces is achieved.

By using a tubular cell with a rectangular cross-section, there is the possibility that several wires or strips can be coated at the same time without increasing the additional effort.

• Figur 1 eine Anlage zum galvanischen Abscheiden im Prinzip,
• Figur 2 einen Schnitt durch einen Teil einer Rohrzelle und einer Schleusenanordnung,
• Figur 2a eine Schnittansicht nach der Linie A-B,
• Figur 2b eine Schnittansicht nach der Linie C-D,
• Figur 2c eine Schnittansicht nach der Linie E-F,
• Figur 2d eine Schnittansicht nach der Linie G-H und
• Figur 2e eine Schnittansicht nach der Linie I-K.

The invention is explained in more detail with reference to the drawing, in which an exemplary embodiment is shown. Show it:

• 1 shows a system for galvanic deposition in principle,
• FIG. 2 shows a section through part of a tube cell and a lock arrangement,
• FIG. 2a shows a sectional view along the line AB,
• FIG. 2b shows a sectional view along the line CD,
• FIG. 2c shows a sectional view along the line EF,
• Figure 2d is a sectional view along the line GH and
• Figure 2e is a sectional view along the line IK.

The system shown in FIG. 1 is used for the galvanic deposition of aluminum from aprotic, oxygen-free and water-free aluminum-organic electrolytes on a strip-like material 1, which in the selected exemplary embodiment is pulled off a roll 2 of an unwinding unit 3, into a tubular cell 5 via a lock arrangement 4 - And passed through this for aluminizing and is wound over a lock arrangement 6 onto a roll 7 of a winding unit 8 after the aluminizing. As will be explained in more detail with reference to FIG. 2, two strips 1 a and 1 b can be aluminized simultaneously by the rectangular cross-sectional shape of the tubular cell 5, it being apparent from FIG. 2 c that partial aluminization is also possible in a simple manner. In the simultaneous aluminizing of two strips, the system shown in FIG. 1 practically only needs to be supplemented by a further roll of the unwinding unit 3 and the winding unit 8. Here, the drive can be carried out by the same drive motor, but with the direction of rotation reversed. Correspondingly arranged anodes are located within the tubular cell 5, which surround the material to be treated on all sides as far as possible.

Immediately behind the lock arrangement 4 and immediately in front of the lock arrangement 6, the tube cell 5 has an outlet connection 9 and an inlet connection 10, which in the selected exemplary embodiment run perpendicular to the longitudinal axis of the tube cell 5. Expediently, however, they are arranged inclined in the current direction, as is the case, for example, in the known tubular cell according to US Pat. No. 3,865,701. The outlet nozzle 9 and the inlet nozzle 10 are connected to an electrolyte circuit which ends in an electrolyte reservoir 11. With the help of a pump 12, the electrolyte is pumped via a line 13, a valve 14 and a flow meter 15 via the inlet connector 10 into the tubular cell 5 and flows in the opposite direction to the movement of the strip-like material 1. The electrolyte hidden via the outlet connector 9 is via a valve 16 and a line 17 are fed to the electrolyte reservoir 11, specifically in front of a filter 18. This electrolyte circuit can be interrupted with the aid of the valves 16, for example when the tubular cell 5 is put into operation. In this case, 23 inert liquid, z. B. via a parallel circuit via open valves 19 and 20 and pipes 21 and 22 with the aid of a feed pump. B. toluene from an inert liquid reservoir 24 through the tubular cell 5, once to remove the atmospheric air from the tubular cell 5 before the electrolyte is pumped through under a protective gas atmosphere N ₂ , and secondly - after the electrolyte has been drained - the tubular cell 5 with inert liquid to be able to clean.

The electrolyte reservoir 11 is sealed airtight with the help of a lid 25 and equipped with a pressure relief valve 26. Of course, all lines are inserted airtight through the cover. Of course, the electrolyte reservoir 11 is also under a protective gas atmosphere N _z . In order to prevent the electrolyte from escaping from the tubular cell 5, diaphragms 27 and 28 are provided on the outlet nozzle 9 and on the inlet nozzle 10, which are provided with slots for the passage of the material 1 to be treated, which are adapted to the cross-section of the material so that as possible little electrolyte can pass into the lock arrangements 4 and 6. Since this cannot be absolutely prevented and there is also the risk that atmospheric air can penetrate via the lock arrangements 4 and 6 - which must let the material to be treated pass through - and thus deteriorate the electrolyte, the lock arrangements 4 and 6 specially designed, namely the lock arrangement 4 consists of three chambers 29 to 31, while the lock arrangement 6 even has five chambers 32 to 36. Each of the chambers 29 to 36 consists of a square tube 37 and these matched chamber walls 38 to 47. Through holes in the chamber walls, 29 to 36 inert gas N _z and / or inert liquid can be introduced into and removed from the individual chambers to form liquid locks, such as will be explained in more detail with reference to Figure 2. In this way, there is also the possibility of washing off the electrolyte still adhering to the material to be treated after passing through the tube cell 5. The chambers 31 and 32 serve primarily to collect the electrolyte, which is supplied to the electrolyte reservoir via a line 48 and a valve 49 11 can be supplied. The line 48 is connected via a valve 50 to the inert liquid reservoir 24 in order to also be able to clean the chambers 31 and 32 with inert liquid.

The chamber wall 39 located between the chambers 29 and 30 is used exclusively for the formation of a liquid lock, the chamber wall 39 of the two chambers 29 and 30 being supplied via a line 51 with the aid of a pump 52 from an inert liquid storage container 53, namely via connecting bores 54 according to FIG. 2a, which are connected via holes 55 to the openings 56 to be treated adapted to the goods 1a and 1b. These openings 56 are now supplied with an amount of inert liquid such that they are always completely filled with inert liquid and thus seal them airtight. At the lower end of the chamber wall 39 there is a connection bore 57 which is connected to the chamber 29. However, it could also be connected to the chamber 30, but this is not shown. The chamber 30 is rather emptied via a connection bore 58 of the chamber wall 40. The inert liquid is in turn fed to the inert liquid reservoir 53 via a line 59 according to FIG. A valve 60 is also provided in this circuit. Connection bores 61 and 62 in the chamber walls 38 and 41 serve for connection to inert gas N ₂ , since the inert liquid should not come into contact with atmospheric oxygen if possible. The line 48 is connected via a connection bore 63 according to FIG.

In the selected embodiment, the roll 2 of the unwinding unit 3 is likewise self-contained and partially filled with inert liquid, this inert liquid being able to be fed from a container 68 via lines 64 and 65 with the aid of a pump 66 and valve 67 and emptied again, if one newly filled roll is inserted. The unwinding unit 3 is also under a protective gas atmosphere N ₂ and in the selected exemplary embodiment is tightly connected to the chamber 29 of the lock arrangement 4 via a square tube connection 69. This square tube connector 69 also has an insert with openings which are adapted to the cross section of the material to be treated and which is connected to the inert circuit system 51 to 53, 59 via a corresponding connection bore and line, as shown on the left in FIG.

The chamber wall 41, like the chamber walls 38 to 40, has openings 70 which are adapted to the cross section of the material to be treated in such a way that as little electrolyte as possible can pass from the tube cell 5 into the camera 31.

As can be seen from FIG. 1, the lock arrangement 6 has two more chambers than the lock arrangement 4, because in the lock arrangement 6 the two chambers 33 and 34 serve to wash the already aluminized goods 1. The chambers 32, 35 and 36 correspond to the chambers 29 to 31 of the lock arrangement 4. The chambers 32 to 36 are basically the same as the chambers 29 to 31. For example, the chamber walls 38, 40 and 41 of the lock arrangement 4 correspond to the chamber walls 42, 43, 45 and 47 of the lock arrangement 6. The chamber wall 39 corresponds to the two chamber walls 41 and 46 of the lock arrangement 6. Since the chamber wall 44 is not only for sealing, but also also serves to wash the already aluminized goods, the connection bore of the chamber 44 is connected to an evaporator 73 via a line 71 and valve 72. With the aid of a feed pump 74, the inert liquid obtained from the electrolyte by distillation is pumped through the longitudinal bores of the chamber wall 44 into the space between the strip-like material 1 and the breakthroughs. The inert liquid emerging into the chambers 33 and 34 and enriched with electrolyte is in turn fed to the electrolyte reservoir 1 via the corresponding connection bores and a pipeline 75.

Because only a small volume of inert liquid of a few liters is removed from the large electrolyte supply for this rinsing or washing process by means of condensation or distillation and loaded with a relatively small amount of rinsed original electrolyte is returned to the electrolyte storage container 11 , Composition and amount of the electrolyte in the reservoir 11 remain practically constant and at the same time the amount of electrolyte discharge through the material 1 to be coated is reduced to a minimum, while rinsing the surface of the already treated material 1 with pure inert liquid is a highly effective cleaning thereof adhering electrolyte.

The minimal residues of highly diluted electrolyte, which may still adhere to the surface of the material 1 when leaving the chamber 34, are then completely removed in the chambers 35 and 36 by means of the intermediate wall 46 designed as a liquid lock with inert liquid. The chamber wall 46 is the same as the chamber wall 39 is formed, which is connected to a reservoir 78 via a connection bore and pipe 76, a valve 77. The inert liquid stored in the storage container 78 is pumped with the aid of a feed pump 79 through the corresponding bores in the intermediate wall 46, which essentially serves as a liquid lock. The inert liquid is returned to the reservoir 78 via a line 99, which communicates with the chambers 35 and 36 or the connection bores of the chamber walls 45 and 46.

FIG. 2 shows a section through part of the tubular cell 5 and through the lock arrangement 4. As can be seen from this, the tubular cell 5 consists of two square tubes 5a and 5b flanged together, in which interchangeable insert pieces 80 and 81 are arranged, which on the one hand are the clear ones Width of the square tubes 5a and 5b are adapted and on the other hand are shaped so that they have longitudinal grooves 82 to 84, in which arranged on both sides of the band-shaped material 1a and 1b anodes 85 and 86 are arranged, which are by means of screws 87 between the Inserts 80 and 81 held and form a unit with them. Here, the longitudinal grooves 82 and 83 are formed so that the inserts 80 and 81 seal against the anodes 85, 86. To shield the anodes 85 from the square tubes 5a and 5b, insulating intermediate pieces 88 are provided on both sides of the anodes 85. The opposite sides of the inserts 80 and 81 are formed so that they form channels 89 for the electrolyte, which is pumped through the inlet and outlet ports 9 to 10.

As FIG. 2c shows, the anodes 85 and 86 are contacted from above with the aid of contact pins 90 and 91, which can be inserted via insulating intermediate pieces 92. As FIG. 2c further shows, the outlet connection 9 is flanged directly onto the square tube 5a.

As can be seen from Figure 2d, the inserts 80 and 81 together with the anodes 85 and 86 and the insulating spacers 88 form an interchangeable unit, the centering of this unit can be carried out in such a way that in the blind bores 93 and 94 of the inserts 80 and 81 centering springs 95 and 96 are arranged, which are supported in the interior of the square tubes 5a and 5b, as shown in FIG. 2e.

FIG. 2e also shows the possibility of contacting the strip-like material 1a and 1b with the aid of resilient contact pins 97 which are connected to the cathode of the power source. The contact pins 97 are guided in the square tubes 5a and 5b with the aid of the insulating intermediate pieces 98. Of course, the contact can also be made in a highly different manner if this is expedient.

It can be seen from FIGS. 2c to 2e that the strip-like material 1a and 1b is only partially aluminized, in the region of the channels 89. If the strip-shaped material 1a and 1b is to be aluminized over the entire width, the electrolyte must have access to it have the entire width of the goods to be treated 1a and 1b, 89 guides for the band-shaped goods 1a and 1b then having to be provided within the channels.

As FIG. 2 shows, the chambers 29 to 36 of the lock arrangements 4 and 6 are also relatively easy to manufacture, since they practically consist only of square chamber walls 38 to 47 and the square tubes 37. In the embodiment according to FIG. 2, two band-shaped goods 1a a and 1 b are aluminized at the same time.

Claims (9)

1. An arrangement for electrodepositing metals, in particular aluminium from aprotric, organo-aluminium elektrolytes which are free from oxygen und hydrogen, on to wire-shaped, tubular or strip-shaped material, comprising a tube cell, closed-off from the exterior, through which the cathodically-contacted material to be treated can be moved, preferably continuously, along anodes in the axial direction, and through which the electrolyte can be pumped angainst the direction of movement of the material with the aid of a closed electrolyte circulating system, in which at each end of the tube cell a liquid lock arrangement is arranged which prevents escape of the electrolyte from the tube cell and which in each case consists of a plurality of chambers, characterised in that the tube cell (5) consists of a plurality of square pipes (5a, 5b), preferably made of metal, which can be flangedly connected to one another and in which exchangeable non-conductive inserts (80, 81) are arranged which, on the one hand, are matched to the internal width of the square pipes (5a, 5b) and, on the other hand, are so shaped that they provide longitudinal grooves (82, 83, 84) and channels (89) for the passage of the material (1a, 1b) to be aluminized, the anodes (85, 86) which surround the material (1a, 1b) to be treated, and the electrolyte.

2. An arrangement as claimed in Claim 1, characterised in that the exchangeable inserts (80, 81) are arranged opposite one another, the outer sides of the inserts being matched to the internal dimensions of the square pipes (5a, 5b) and the oppositely arranged sides of the inserts being provided with recesses (82, 83, 84) for covering the material (1 a, 1 b) to be treated an the electrolyte, and for holding the anodes (85, 86) which surround the material (1 a, 1 b) to be treated.

3. An arrangement as claimed in Claim 2, characterised in that the recesses (82, 83, 84) for the anodes (85, 86) are so designed that the two inserts (80, 81) are supported on the anodes (85, 86).

4. An arrangement as claimed in Claim 2 or Claim 3, characterised in that the inserts (80, 81) are firmly connected to the anodes (85, 86) in such a way that they form a unit which can be inserted into the square pipes (5a, 5b), the length of the unit being such that the end face of the unit does not fall in the plane of the connecting flanges of the square pipes (5a, 5b).

5. An arrangement as claimed in one of Claims 1 to 4, characterised in that contact pins (90, 91), which can be insert in insulated manner from the exterior of the square pipes (1 a, 1 b), are used for the contacting of the anodes (85, 86).

6. An arrangement as claimed in one of Claims 1 to 5, characterised in that, for contacting the material (1a, 1b) to be treated, resilient contact pins (97) are used which can be inserted into the square pipes (5a, 5b) from the outside in insulated and sealed manner and which terminate in the longitudinal grooves (84) for leading the material (1 a, 1 b) to be treated.

7. An arrangement as claimed in one of Claims 1 to 6, characterised in that the chambers ( 29, 30, 31, 32, 33, 34, 35, 36) of the liquid lock arrangements (4, 6) also have a rectangular shape in cross-section.

8. An arrangement as claimed in one of Claims 1 to 7, characterised in that the inserts (80, 81) of the tube cell (1) and the chambers (29, 30, 31, 32, 33, 34, 35, 36) of the liquid lock arrangements (4, 6) are so designed that a plurality of strip-shaped workpieces (1a, 1b) can be continuously electroplated at the same time.

9. An arrangement as claimed in one of Claims 1 to 8, characterised in that the inserts (80, 81) which are connected to form a unit, can be pressed against the inner walls of the square pipes (5a, 5b) with the help of centering springs (95,96).

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