DE202013006233U1 - Plant for wet-chemical cutting of nickel layers - Google Patents

Abstract

Plant for the wet chemical deposition of nickel layers from a nickel bath (14) with a container (12) for the nickel bath (14) and with a magnet (1) for fixing nickel particles in the nickel bath (14) during the deposition.

Description

The wet-chemical deposition of nickel layers has been a well-known and extensively used process for a long time. The layers are also referred to as so-called chemical nickel layers, which distinguishes them from galvanic nickel layers.

Products to be coated are suspended in a suitable manner, for example on a standard electroplating rack, and introduced into a special nickel bath, which is e.g. B. nickel sulfate-based with a nickel content of z. B. 4 g to 8 g of nickel per liter can be constructed. Hypophosphite can be used as the reducing agent; In general, complexing agents are additionally provided.

Such methods have been used, inter alia, for products which are to be given improved wear resistance or improved corrosion protection by the coating. A well-known example are housing of fuel pumps for internal combustion engines, for example in cars.

The prior art is additionally referred to the EP 02 102 609 , which deals with a container for the chemical metallization, in particular the nickel deposition, and also deals with the filtering out of particles from the nickel bath.

The invention has for its object to provide an improved system for wet-chemical deposition of nickel layers.

This object is achieved by the system comprises a magnet in or on the nickel bath for fixing nickel particles in the nickel bath.

The inventor has found that the nickel particles are not only in terms of the mentioned in the EP 02 102 609 Thematic wall deposits can be problematic. They can also adhere to the coated products or even grow by further deposition and thus at least affect the surface quality. This may affect the frictional properties, but it can also emanate from separating or separated during operation of the product further problems.

Further, the inventor has found that the recirculation and filtration of the nickel bath already mentioned in the cited application offers considerable improvements in this regard, but leaves room for further improvement. These further improvements relate to the relief of the filter and / or the additional improvement of the particle freedom of the products, depending on the individual application. The improvement of the invention consists of magnetically collecting nickel particles from the nickel bath by using a magnet in or on the nickel bath at least during the deposition.

By the way, the term "nickel particles" also means particles which are originally based on materials or impurities other than those of nickel, but which have been or have been coated in the bath with nickel. They also have the property of being attracted to a magnet by the nickel coating and can thus be directed in the nickel bath to the magnet and fixed in its surroundings or on it. In any case, they are in fact deprived or immobilized in the part to which they migrate to the magnet and remain there. If necessary, they can be removed (with or without the magnet) from the nickel bath.

By reducing the particle concentration in the nickel bath and / or reducing the concentration of at least the larger of the particles (which experience has shown to be more strongly attracted), the adverse effects of the particles are reduced, in particular, depending on the application, the load on the filter in the recirculation system , the growth on the tub walls and / or the adhesion and growth of particles on the coated products.

In particular, the magnet can also be used to collect particles in size ranges which are not detected or poorly detected by the customary filters, in particular particles in a range between 0.1 μm and 3 μm (based on the smallest particle size; other dimensions can be larger ). Particles below the lower limit will not interfere significantly in many cases, and particles above the upper limit may also be detected by the filter. Although such small particles disturb less than larger, but they can grow within a short time, z. B. grow within one hour to 30 microns.

Preferably, the magnet is a permanent magnet, although an electromagnet is also conceivable. The permanent magnet is associated with less effort and experience is basically sufficient. However, relatively strong permanent magnets are to be preferred, in particular those made of alloys of rare earths such as neodymium or samarium. Good examples are NdFeB or SmCo.

The magnet according to the invention can nickel particles in the nickel bath in various ways attract. For example, it may be externally supported on a wall of a tub containing the nickel bath. The magnetic field then passes through the wall into the nickel bath and produces the desired attractive effect. Further, the magnet could also be mounted outside, for example, a recirculation line that carries the nickel bath in a recirculation process. For example, in the case of a magnet arranged outside a circulation line, a line part could be exchangeable, it being possible to switch over between two lines in the sense of a mutual bypass ratio.

In particular, however, it is preferred that the magnet is immersed in the nickel bath during deposition. This means, because of the possibility of separating layers between the magnet and the nickel bath which will be explained below, that the superficial liquid level in the nickel bath is at least higher than the underside of the magnet and preferably as its top side and the magnet at least one larger part of its environment (the full solid angle around it) is surrounded by the nickel bath. For example, when the magnet is immersed in a pocket, there may still be a free space without nickel bath above the magnet.

Since the magnetic material, in particular of a permanent magnet, can react with or be damaged by the nickel bath, the magnet is preferably coated, for example painted.

Alternatively or additionally, the magnet can be clad with an interchangeable (including removable and cleanable) Abscheidefläche for example from a film. In principle, this separation surface can also replace the coating just mentioned, but preferably both a coating (including a tight foil covering) of the magnet and an exchangeable separation surface are provided for safety. The latter then has, besides the separation of the magnetic material from the nickel bath, in particular the task of absorbing adhering and growing material on the surface facing the nickel bath and of making it easily removable by removing the separation surface. For this purpose, the Abscheidefläche can in principle be exchanged for a new or cleaned or even easily separated from the adhering material, the latter can be much easier after removing.

A special case of the exchangeable separation surface is a separation surface which is movable during the coating process by a movement device, in particular a film web moved during the process. For example, this can be moved between two windings (an unwinding and a winding winding), wherein the windings are preferably arranged above the bath and above the magnet. The film web therebetween may then travel in an approximate U-shape (not necessarily with parallel legs) from the windings downwardly, around the magnet and back up, preventing the film from adhering or growing too thickly be removed.

In this case, the magnet can be arranged, for example, in a rod-shaped shape in the curvature of the U-shape. The remaining end openings (between the expiring and the auflaufenden film web part) are either tolerable, especially with additional coating of the magnet, or can be at least largely closed by fixed trim parts.

The above explanations also apply to the case of a magnet arranged outside the nickel bath (the tub and the circulation pipe). For example, a sheet material within a wall of a nickel bath tub may be exchanged between and / or moved during deposition processes. Basically, the term "replacement" in the present context is not limited to replacing the corresponding separation surface with another, but may also mean cleaning it and reusing it. It is ultimately about removing the deposited nickel particles from the bath.

Favorable web speeds for the moving separation surface, in particular in the concrete embodiment just described, are approximately in the range of tenths to tens of cm / h, that is approximately between 0.1 and 50 cm / h, where 0.5 cm / h and 1 cm / h. h as the lower limit and, on the other hand, 10 cm / h, 5 cm / h and 3 cm / h as the upper limit, respectively, are increasingly preferred.

As already explained, the invention is preferably used in combination with a pump and a filter for circulating the nickel bath. In this context, the magnet is preferably arranged in the vicinity of the suction port, that is to say it is intended, above all, to serve to reduce the particle concentration in this environment before it enters the filter. This relieves the filter on the one hand; On the other hand, the particles after their residence time in the bath are larger than before upon re-entry into the bath, so that the magnet is particularly effective there. He can complement himself with the filter to the extent that typically the Filter filters out only particles with a certain minimum size and the magnet also collects even particles below this minimum size. In many cases, very small particles are tolerable and have negligible harmful effects.

As already mentioned in the beginning EP 02 102 609 1, a trough shape with rounded corners is advantageous for the effectiveness of the pump-supported circulation of the nickel bath, wherein a minimum radius of curvature of approximately 5 cm, preferably 10 cm, is preferred.

Further, the adhering to the magnet or its coating or Abscheidefläche material is preferably supplied for reuse.

Finally, it has been found that the invention works particularly well in conjunction with relatively low-phosphorus nickel baths. As already stated, hypophosphite can be used as a reducing agent in the nickel bath (in particular based on nickel sulphate). The phosphorus content is then in percent by weight and, based on the nickel content, preferably at most 6%. On the other hand, it should preferably be at least 3%.

Finally, the invention is also directed to a product accordingly provided with a so-called chemical nickel layer, which, however, can be further processed beyond the nickel coating, in particular may have additional coatings. It is further directed to a suitable system for carrying out the method described, including the implicit disclosure of device details in the above, to the following embodiment and also to the contents of the above-cited EP 02 102 609 can be referenced. Finally, the invention is also directed to a corresponding use of a magnet, in particular permanent magnet.

In the following the invention will be explained with reference to an embodiment. The features described here can also contribute individually and in other combinations to the solution of the problem and should not be disclosed only in the following combination. Incidentally, they apply to all categories of claim. In addition, for better understanding on the EP 02 102 609 directed.

1 shows a schematic view of a magnet according to the invention for a wet-chemical nickel bath and

2 also shows a schematic view of such a bath with hinged magnet according to 1 ,

In 1 is with 1 an inventive permanent magnet, namely a NdFeB magnet with rod shape, wherein the rod longitudinal axis is perpendicular to the plane. In fact, it is a certain number of individual magnets, which, as a result of their mutual attraction, can be easily strung together and thus, as it were, connected in series and, as a result, hold each other together and form a rod. These magnets have a cylindrical shape in the present example. They are with a paint 2 protected, which could also be a close-fitting, perhaps glued, foil. The magnetic bar 1 is via a mechanical mount 3 held from above (the vertical in 1 corresponds to the gravitational direction), wherein z. B. the in 1 indicated below circular plates at the end of the holder 3 could be glued on. At the top of the bracket 3 There is a suspension device that can be brought in a suitable manner over a corresponding bath, but not shown here.

The chemical nickel bath is merely indicated by the horizontal line 4 intended to symbolize the liquid surface level; the magnetic bar 1 is so immersed. Above the liquid level 4 There are two windings 5a and b, wherein the plastic film web wound thereon in a U-shape from the winding 5a As indicated by the arrows, rolled down, under the magnetic bar 1 passed through and on the other side on the winding 5b being rolled up. A typical speed is 2 cm / h, depending on the amount of nickel deposited.

Nickel particles from the bath under the mirror 4 become by the bar magnet 4 attracted and divorced essentially outside the film web 6 on, especially in the lower semicircular segment of the circular circumference of the bar magnet. The precipitating there material of nickel particles is so with the film web 6 pulled up and on the winding 5b rolled up. It can, for. B. after simple passage of the entire film web 6 with the winding 5b taken and z. B. by peeling off the films (at high bending of the same) or be replaced in another form and reused.

The bath is a typical wet-chemical nickel-based nickel-coating bath with present z. B. 6 g / l nickel. In this case, 4.5 percent by weight of phosphorus in the form of hypophosphite and also a conventional complexing agent are typically present with respect to nickel.

2 additionally shows the bath container, according to the EP 02 102 609 , in which 11 an outer container with a Perforated intermediate container 12 and in one, silicone film 13 shows. In it is already based 1 mentioned liquid 14 coming from a pump 15 is circulated with not separately drawn particulate filter. Intake openings serve this purpose 16 near the surface of the liquid 14 , In the vicinity is, as indicated, of a circumferential film web 6 coated magnetic bar 1 , The windings 5a , b are only hinted at and the mechanical mount 3 for the magnetic bar 1 omitted for simplicity.

The largely on at the film web 6 adhering particles freed nickel bath solution is through the suction port 16 the pump 15 and downstream of it two exhaust pipes 17 and 18 fed. These also extend perpendicular to the plane and provide, as indicated in the drawing and in the cited EP 02 102 609 shown in detail, for an effective circulation within the inner container 12 or the film 13 , Decisive are also the rounded corners on the bottom left and right.

The combination of the effective circulation, the particle filtration and the particle collection by the magnet according to the invention 1 ensures an extremely low particle load. This wall deposits are low and are mainly the coated products of high quality. This may for example be important in fuel pumps for z. As motor vehicles in which adhering nickel particles can cause malfunction in the engine.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 02102609 [0004, 0007, 0022, 0025, 0026, 0033, 0034]

Claims (13)

Plant for the wet-chemical deposition of nickel layers from a nickel bath ( 14 ) with a container ( 12 ) for the nickel bath ( 14 ) and with a magnet ( 1 ) for fixing nickel particles in the nickel bath ( 14 ) during the deposition. Plant according to claim 1, in which the magnet ( 1 ) is a permanent magnet, in particular a rare earth magnet. Plant according to claim 1 or 2, adapted to immerse the magnet in the nickel bath during deposition. Plant according to claim 3, in which the permanent magnet ( 1 ) a protective layer ( 2 . 6 ) through which it is separated from the nickel bath ( 14 ), preferably a coating. Installation according to one of the preceding claims, with an exchangeable separation surface ( 6 ), through which the permanent magnet of the nickel bath ( 14 ), preferably a film web ( 6 ), wherein deposited nickel particles by exchanging the Abscheidefläche ( 6 ) can be removed. Plant according to claim 5, in which the separation surface ( 6 ) during the deposition in an exchanging manner by a movement device through the nickel bath ( 14 ) can be moved. Plant according to claim 6, in which the separation surface ( 6 ) during deposition between two over the nickel bath ( 14 ) arranged windings ( 5a , b) suspended as web material and through the nickel bath ( 14 ), wherein the magnet ( 1 ) is arranged in a U-turn of the web material between an outgoing and an incoming web part. Plant according to claim 7 designed for a web speed during the deposition between 0.1 and 50 cm / h. Plant according to one of the preceding claims, in which a pump and a filter are provided, with which the nickel bath ( 14 ) can be circulated during the deposition and filtered on particles, wherein the magnet ( 1 ) closer to a suction port ( 16 ) of the pump ( 15 ) to the nickel bath ( 14 ) is arranged as at a discharge port ( 17 . 18 ) of the pump ( 15 ). Plant according to claim 9, in which a container ( 12 ) of the nickel bath ( 14 ) has rounded corners with a radius of curvature of over 5 cm. Plant according to claim 5, also in connection with a further one of the preceding claims, designed to be arranged on the separation surface ( 6 ) deposited nickel material after exchange of the separation surface ( 6 ) is reused. Plant according to one of the preceding claims with a phosphorus content in the nickel bath ( 14 ) of less than 6 weight percent based on the nickel content. Using a magnet ( 1 ), in particular permanent magnets, for a plant according to one of claims 1 to 12.

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