DE102013212474A1 - Powder-containing component with a adhesion-reducing layer and process for its preparation - Google Patents

Abstract

The invention relates to a component (11) carrying powder (10), such as a pipeline or a conveying funnel, on which an adhesion-reducing layer (12) is applied, and a method for its production. According to the invention, it is provided that plastic particles (23), for example made of Teflon, are dispersed in the layer at least in one cover layer (22) and also form a surface portion of the surface (25). The metallic matrix of the cover layer (22) consists of nickel. The pairing of nickel and a plastic, preferably Teflon, has the surprising effect that the tendency of the conveyed powder to clump is reduced. It is therefore possible to dispense with powder additives, which can lead to contamination in the layer produced during cold gas spraying, for example.

Description

The invention relates to a powder-carrying component of a powder conveying system. Moreover, the invention relates to a method for producing such a component.

Powder-carrying components of powder conveying systems are for example from the EP 484 633 B1 known. Here comes a powder conveyor system in a device for cold gas spraying used. The powder must be metered into the carrier gas stream in order to be subsequently deposited with a cold gas jet on a substrate to be coated. In this case, it is important that the powder particles do not stick together, since the parameters of the cold gas spraying must be selected taking into account the particle mass. However, agglomerates of particles behave differently than individual particles, which is why the deposition parameters only lead to satisfactory layer results when the particles are present in isolated form in the cold gas jet.

In order to avoid clumping of the powder during cold gas spraying, according to the prior art, a further powder of aluminum oxide (order of magnitude F360) can be added to the powder. This addition improves the flow properties of the powder, so that a caking of the powder particles can be largely prevented. However, it must be accepted that the particles of alumina are at least incorporated in small quantities in the layer to be produced. In addition, due to the hardness of the alumina has abrasive properties, which is why the components of the powder conveyor system are subjected to a certain wear.

The object of the invention is to provide a component of a powder conveying system with which a promotion of pure powder is possible without this clumps.

This object is achieved with a powder-carrying component of the type specified according to the invention that the component of the powder conveyor system is equipped with a adhesion-reducing layer having at least one adhesion-reducing surface-providing cover layer. This cover layer has a metallic matrix of nickel, in which particles of a plastic are embedded, which form at least part of the surface. According to a particular embodiment of the invention, these embedded particles of PTFE (Teflon). Advantageously, the excellent sliding friction properties of the metal nickel are used in combination with the adhesion-reducing properties of plastics, in particular PTFE, in order to reduce the friction of the powder particles on the walls of the component.

Components with adhesion-reducing layers are known per se. For example, in the DE 297 19 716 U1 discloses such a component, which is used as a separating plate for the production of multi-layer resin-bonded circuit boards used. These printed circuit boards must be pressed during their manufacturing process, with the tools for pressing after the successful production of printed circuit boards as easy as possible to be removed from them. Here, the said dividers are used. These baffles have a dispersion layer that provides a matrix of nickel. In this matrix particles of Teflon (polytetrafluoroethylene) are introduced, which also form part of the surface. The layer may additionally be subjected to a heat treatment to improve the non-stick properties, wherein at least the surface Teflon particles are melted and thereby change their shape and their structural properties.

Besides, it is according to the US 2011/0083885 A1 It is known that nickel coatings on plastic parts can be produced by introducing catalytic particles into an electrically insulating layer composite, which in a subsequent electroless nickel coating reduces the nickel ions in the coating electrolyte and thereby leads to the formation of nuclei for layer formation. These seeds then grow together to form the coating to be formed.

Surprisingly, however, the effect of an adhesion-reducing coating of the powder-carrying components that a clumping of the pumped powder is reduced. In principle, the adhesion-reducing properties of the walls do not affect powder particles which are guided inside the powder-carrying component. The positive effect of the adhesion reducing properties on the reduction of the tendency to agglomerate of the conveyed powder is explained by the fact that the mechanisms of adhesion of powder particles to the walls of the powder-carrying component contribute to initiation of the clumps of the conveyed powder. If these possibilities of a formation of clots are already suppressed from the outset, then the powder flows largely unhindered through the powder conveying system, without causing lumps. On additives that prevent the tendency to clump, can thus be advantageously dispensed with.

According to one embodiment of the invention, the powder-carrying component may consist of a metallic material. Metallic materials can advantageously be coated in a simple way, for example electrochemically, with nickel, wherein in the case of an electrochemical coating the particles of plastic can be incorporated into the layer that forms.

According to another embodiment of the invention, it is provided that the component consists of a plastic and on this a starting position for the electroless plating with metal is applied. This starting layer has a matrix of a synthetic resin in which metallic particles are incorporated as nuclei for electroless plating. These seeds are advantageous in that electroless metal plating can also be used on a plastic part to produce the adhesion-reducing layer. As adhesion-reducing layers should be understood in the context of this invention, which itself produce a lower adhesion of powder particles to the surface of the coated component, as compared with the uncoated component. As a result, the coating has the effect of reducing the adhesion.

Nickel is used as the metallic matrix. This is a metal, which provides a surface with intrinsically good adhesion properties compared to other metals. The plastic used in particular polytetrafluoroethylene (also called PTFE or Teflon) is used, the adhesion-reducing properties are well known. Again, depending on the application, other plastics are conceivable, such as. Nylon.

The ability to provide components made of plastic with layers that reduce the adhesion, makes advantageous the use of the coatings in large-scale powder-carrying components such as piping possible. However, the components can not be coated in a bath because they are generally too large in size. The coating must then be produced for example by brush-plating, wherein the electrolyte is applied in this method by means of a brush or a sponge-like structure on the surface of the component.

In addition, the object is achieved with the above-mentioned method according to the invention that, if the component consists of a plastic, on the powder component leading a starting layer is applied with a matrix of a synthetic resin, wherein in the matrix metallic particles as germs for a subsequent electroless plating can be stored. In the next step or in the first step, if the component consists of a metal, at least one adhesion-reducing surface-providing cover layer is produced chemically or electrochemically on the starting layer, the cover layer having a metallic matrix in which particles of a plastic are embedded are that form at least part of the surface. This can be done in the manner already described, for example by brush-plating. It also large components such. As conveying lines for powder coated.

Moreover, the method according to the invention can be advantageously configured when the cover layer is subjected to a heat treatment by applying hot air to the surface until the particles of plastic are melted at least at the surface. By the heat treatment, the adhesion-reducing behavior of the layer can advantageously be further improved. By melting the particles they are smoothed and can also partially spread on the metallic surface formed by the matrix of the cover layer. Depending on the distance between the particles protruding through the surface of the matrix, neighboring particles can also be joined together by the heat treatment. With a sufficiently dense distribution of the particles on the surface, it is even possible to produce an at least substantially closed Teflon layer, which is mechanically supported and reinforced by the stable matrix of the cover layer. Here, the advantage of the metal-plastic material combination is exploited in a special way, this pair of materials not only provide favorable properties of a reduction in adhesion available, but also a high stability to mechanical stress such as abrasion by powder particles. Therefore, this pairing of materials is particularly suitable for the powder-carrying components.

Advantageously, the metallic particles in the starting position of palladium and / or copper and / or nickel and / or iron. These metals are particularly advantageous in particular to catalytically support nucleation for subsequent electroless metal deposition. In particular, layers of nickel can be deposited with these catalyst metals.

It is furthermore advantageous if the volume fraction of metallic particles in relation to the synthetic resin of the matrix in the starting position is at least 60 and at most 85%. On the one hand, such a degree of filling ensures that the matrix of the resin material reliably binds the metallic particles. On the other hand, there are enough on the surface of the starting position metallic particles as nucleating agents available, so that a subsequent electroless plating can be produced in an economically acceptable time.

Advantageously, the cover layer has a thickness of at least 5 and at most 15 microns. From a technical point of view, a compromise can be found which is guaranteed in this thickness range. On the one hand, it has to be taken into account that the layer has to be thick enough so that, in the case of a subsequent heat treatment, the thermal load of the component, if it is made of plastic, can be reduced by dissipating the heat into the cover layer. For this purpose, layers as thick as possible are to be provided. On the other hand, the cover layer must not flake off due to residual stresses during the heat treatment. Therefore, the top layer must not exceed a thickness of 15 microns. In addition, thicker layers would also be more expensive to produce (more material, longer production time), so that thicker layers would be less economical to manufacture. Finally, due to the requirement for the mechanical stability of the cover layer, the layer thickness must not be less than 5 μm.

Advantageously, a metallic intermediate layer can be provided between the starting position and the cover layer. This intermediate layer is advantageously less expensive to produce than the cover layer provided with the particles of plastic. Therefore, advantageously, larger layer thicknesses can be produced inexpensively. In addition, an intermediate layer of pure nickel or another metal improves the adhesion of the cover layer on the starting position.

Further details of the invention are described below with reference to the drawing. Identical or corresponding drawing elements are each provided with the same reference numerals in the individual figures and will only be explained several times to the extent that differences arise between the individual figures. Show it:

1 an embodiment of the powder-carrying component according to the invention as a schematic detail,

2 the section II off 1 in the illustration before and after the heat treatment according to an embodiment of the method according to the invention,

3 an embodiment of the component according to the invention, designed as a feed hopper for a powder conveyor, in section and

4 a further embodiment of the component according to the invention, designed as a pipe made of plastic, wherein the cross-sectional area is shown in section.

Of the 1 can be cut as a particle 10 leading component 11 take which with a adhesion-reducing layer 12 is provided. The component consists of a core area 13 , this core area 13 with fibers 14 is reinforced. To the core area 13 closes a border area 15 this differs from the core area only in that it is not reinforced with fibers. Alternatively, a pure plastic component could be provided without fiber reinforcement.

On the component 11 is the layer 12 , This consists in 1 from three layers. On the component is initially a starting position 16 coming from a matrix 17 made of plastic and embedded in this matrix metallic particles 18 consists. The interface 19 between the component 11 and the starting position 16 is free of fibers 14 because of the edge area 15 , as already mentioned, has no fibers. Metallic particles 18 in the starting position 16 however, touch the interface 20 between the starting position and an intermediate position 21 made of nickel. These metallic particles 18 at the interface 20 Namely form the nuclei for electroless deposition of the nickel of the intermediate layer 21 , The subsequent cover layer 22 is then also de-energized (or alternatively on the already conductive intermediate layer 20 also galvanic) deposited, wherein during the chemical or electrochemical deposition in the electrolyte dispersed particles 23 made of plastic in the forming metallic matrix 24 be stored. These particles 23 lie by the cover layer 22 formed surface 25 free, where there is an effect of reducing the adhesion of the surface 25 through the particles 23 Made of plastic is guaranteed. This is also retained when the top layer is subject to wear, as in a removal of the top layer 22 the inside of the matrix 24 lying particles 23 be exposed from plastic. With progressive wear of the cover layer 22 a subsequent heat treatment may be the adhesion properties of the worn liner 22 improve again.

In 2 can be seen as by a heat treatment, the effect of a reduction in the adhesion of the surface 25 is reached. The part of the surface 25 the top layer 22 before the heat treatment, the break line is shown on the left. It stands out that the the surface 25 piercing particles 23 have a substantially round shape. To the right of the break line are the particles 23a on the surface 25 shown after the heat treatment. These have a smoother surface. Neighboring particles 23a have deformed so far, that these have grown together and represent a uniform surface in this area. Overall, this represents a smaller part of the surface area of the matrix material 24 to disposal. Depending on the density of the particles 23a can also be an extensive sealing of the surface 25 respectively. This can be advantageous depending on the application.

In 3 is a feed judge 30 made of steel. This may for example be arranged at the bottom of a reservoir for powder (not shown). The inside of the funnel is with a single layer 22 electrochemically coated, which is the location 22 according to 1 equivalent. Since the feed funnel 30 Metallic, the location can be 22 be deposited directly on the inner surface.

In 4 is a pipe 40 made of a thermoplastic material. This tube can be used as a conveying line for powder and has a layer composite inside 12 according to 1 on, but in 4 not shown in detail. The coating method according to the invention is also advantageously suitable for lining longer pipes with the adhesion-reducing layer composite 12 (The method has already been explained in detail above).

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 484633 B1 [0002]
• DE 29719716 U1 [0006]
• US 2011/0083885 A1 [0007]

Claims (11)

Powder leading component ( 11 ) a powder conveying system with a adhesion-reducing layer ( 12 ) having at least one adhesion-reducing surface ( 25 ) cover layer ( 22 ), wherein the cover layer - a metallic matrix ( 17 ) of nickel, - in the particle ( 23 ) are embedded from a plastic which at least a part of the surface ( 25 ) form. Component ( 11 ) according to claim 1, characterized in that it consists of a metallic material. Component ( 11 ) according to claim 1, characterized in that it consists of a plastic and on this a starting position ( 16 ) is applied for electroless plating with metal, wherein the starting layer - has a matrix of a synthetic resin, - in the metallic particles ( 18 ) are incorporated as nuclei for electroless plating. Component ( 11 ) according to claim 3, characterized in that the metallic particles ( 18 ) in the starting position ( 16 ) consist of palladium and / or copper and / or nickel and / or iron. Component ( 11 ) according to one of the preceding claims, characterized in that the volume fraction of metallic particles ( 18 ) in relation to the resin of the matrix ( 17 ) in the starting position ( 16 ) is at least 60 and at most 85%. Component ( 11 ) according to one of the preceding claims, characterized in that the cover layer ( 22 ) has a thickness of at least 5 and at most 15 microns. Component ( 11 ) according to one of the preceding claims, characterized in that at least those on the surface ( 25 ) of the cover layer ( 22 ) particles ( 23 ) are heat treated from the plastic. Component ( 11 ) according to any one of the preceding claims, characterized in that the particles ( 23 ) consist of PTFE. Process for the preparation of a powder-carrying component ( 11 ) a powder conveying system with a adhesion-reducing layer ( 12 ) with the following working step: - on the surface of the component at least one adhesion-reducing surface is chemically or electrochemically 25 ) cover layer ( 22 ), wherein the cover layer ( 22 ) a metallic matrix ( 17 ), in which particles ( 23 ) are embedded from a plastic which at least a part of the surface ( 25 ) form. Method according to claim characterized in that the component ( 11 ) is made of a plastic material and the following operation is preceded by the procedure: - on the component ( 11 ), a starting layer forming the surface for further coating steps ( 16 ) is applied with a matrix of a synthetic resin, wherein in the matrix metallic particles ( 18 ) are stored as seeds for subsequent electroless plating. Method according to claim 10, characterized in that the cover layer ( 22 ) is subjected to a heat treatment by the surface ( 25 ) is applied with hot air or the component is introduced into an oven until the particles ( 23 ) are melted from plastic on the surface.

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