WO2014206705A1

WO2014206705A1 - Powder-carrying component having an adhesion-reducing layer and method for production thereof

Info

Publication number: WO2014206705A1
Application number: PCT/EP2014/061705
Authority: WO
Inventors: Axel Arndt; Uwe Pyritz; Manuela Schneider; Oliver Stier
Original assignee: Siemens Aktiengesellschaft
Priority date: 2013-06-27
Filing date: 2014-06-05
Publication date: 2014-12-31
Also published as: DE102013212474A1

Abstract

The invention relates to a powder (10)-carrying component (11) as for example a pipe or a feed hopper, to which an adhesion-reducing layer (12) is applied, and to a method for producing same. According to the invention, plastic particles (23), for example Teflon particles, are dispersedly distributed in the layer at least in a top layer (22) and also form a surface portion of the surface (25). The metal matrix of the top layer (22) consists of nickel. The combination of nickel and a plastics material, preferably Teflon, has the surprising effect that the tendency of the conveyed powder to form lumps is reduced. In this way, no powder additives are required, which for example during cold gas spraying may result in impurities in the layer so produced.

Description

description

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

The invention relates to a powder-carrying component of a powder conveying system. Moreover, the invention relates to a Ver ^¬ drive for the production of such a component. Powder-carrying components of powder conveying systems are known, for example, from EP 484 633 B1. 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 have to 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 if 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 (of the 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 in the present invention in that the component of the powder conveyor system is provided with a adhesion-reducing layer having at least one adhesion-reducing surface-providing cover layer. This topsheet has a metallic Mat ^¬ rix of nickel, a ^¬ are supported in the particles of a plastic material, at least part of the surface education the. 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. In the example, DE 297 19 716 Ul discloses Note that such a component, which takes as a separating plate for the Ferti ^¬ supply of multi-layered resin-bound printed circuit boards for use. These 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 separating ^sheets have a dispersion ^layer which provides a matrix of nickel. Particles of Teflon (polytetrafluoroethylene), which also form part of the surface, are introduced into this matrix. The layer may be additionally subjected to Verbes ^¬ provement of the non-stick properties to a heat treatment, wherein at least the Teflon particles at the surface are melted and thereby change their shape and their structural properties.

In addition, it is known from US 2011/0083885 Al that nickel coatings on plastic parts can be produced by converting catalytic particles into an electric insulating layer composite are introduced, which reduce the nickel ions in the coating electrolyte in a subsequent electroless nickel coating and thereby lead to the formation of nuclei for film formation. These seeds then grow together to form the coating to be formed.

However, the effect of an adhesion-reducing coating on the powder-carrying components is surprising in that a clumping of the conveyed 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 clot formation 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 Me ^¬ tall is applied. This starting position has a matrix of a synthetic resin, in the metallic particles as germs are stored for electroless plating. These germs are advantageously suitable for electroless metalli ^¬ cal coating 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. Here han ^¬ delt it is a metal, which provides a surface with good se liability own sheep ^¬ th available 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 for example, by Brush plating are generated, wherein the electrolyte is applied in this method with ^¬ means of a brush or a sponge-like structure to the surface of the component.

In addition, the object is achieved with the aforementioned method according to the invention that, if the component consists of a plastic, on the powder leading component a starting layer is applied with a matrix of a synthetic resin, wherein in the matrix metallic particles as germs for a subsequent electroless electrochemical coating be stored. In the next step or in the first step, when the component consists of a metal is formed on the starting layer chemically or electrochemically at least an adhesion-reducing surface-providing topsheet, said topsheet having a me--metallic matrix, are embedded in the particles of a synthetic ^¬ material that form at least a part of the Oberflä ^¬ surface. This can be done in the manner already described, for example by brush-plating. It also large components such. For example, conveying lines for powders are to be coated.

The inventive method can advantageously be designed from ^¬ Moreover, if the topsheet is subjected to a heat treatment by coating the surface with hot air is acted upon until the particles are melted plastic at least on the surface. Due to the heat treatment, the adhesion-reducing behavior of the

Layer advantageous further improve. By melting of the particles, they are smoothed and may also partially on the metallic surface, which is formed by the mat rix ^¬ of the liner, from spreading. Depending on the distance of the projecting through the surface of the matrix particles adjacent particles can also be joined together by the action Wärmebe ^¬ respectively. With a sufficiently dense distribution of the particles on the surface can even be at least substantially closed

Produce 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 layer of palladium and / or copper and / or nickel and / or iron consist. 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 me ^¬-metallic particles relative to the resin of the matrix in the starting position is at least 60 and at most 85%. With such a degree of filling is the one hand still provides ^¬ ensure that the matrix of the resin material binds the metalli ^¬ rule particles reliably. On the other hand, however, sufficient metallic particles are also available as nucleating agents on the surface of the starting layer so that a subsequent electroless coating can be produced in an economically acceptable time.

Advantageously, the cover layer has a thickness of at least 5 and at most 15 ym. From a technical point of view, a compromise can be found which is guaranteed in this thickness range. To take into account on the one hand, that the layer must be sufficiently thick, so that at a connect ^¬ the heat treatment, the thermal load on the component, if it is made of plastic, can be reduced by dissipation of the heat in the topsheet. 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 cover layer may have a thickness of 15 ym not exceed about ^¬. In addition, thicker layers would also be more expensive to produce (more material, longer manufacturing ^¬ time), so that thicker layers would be uneconomical in their production. 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 interim rule ^¬ location is advantageous cost-effective to manufacture ment, as provided with the particles of plastic cover layer. 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:

Figure 1 shows an embodiment of the invention Pul ^¬ ver leading component as a schematic detail, the detail II of Figure 1 in the illustration before and after the heat treatment according to an embodiment of the method according to the invention, an embodiment of the inventive component, designed as a feed hopper for a powder conveyor, im Section and another embodiment of the erfindungsge ^¬ MAESSEN component, designed as a pipe made of plastic, wherein the cross-sectional area ^{geschnit ¬} th is shown.

Of Figure 1 can be used as a particle segment 10 ^¬ de lead component found in 11, which is provided with an adhesion-reducing layer ver ^¬ 12th The component consists of a core region 13, wherein this core region 13 is reinforced with fibers 14. The core region 13 is adjoined by an edge region 15, which differs from the core region only in that it does not contain fibers. strengthens. Alternatively, a pure plastic component without fiber reinforcement could also be provided.

On the component 11 there is the layer 12. This consists in Figure 1 of three layers. On the component is initially a starting position 16, which consists of a matrix 17 made of plastic and embedded in this matrix metallic particles 18. The boundary surface 19 between the component 11 and the starting layer 16 is free of fibers 14, since the edge region 15, as already mentioned, has no fibers on ^¬ . However, metallic particles 18 in the starting layer 16 touch the interface 20 between the starting layer and an intermediate layer 21 of nickel. These metallic particles 18 at the interface 20 that is forming the nuclei for a de-energized se deposition of the nickel of the intermediate layer 21. The subsequent ^¬ sequent topsheet 22 is then also energized (or alterna ^¬ tively on the already-conducting intermediate layer 20 also galvanic ^¬ nic) deposited, wherein during the chemical or electrochemical deposition dispersed in the electrolyte particles 23 of plastic in the forming metallic

Matrix 24 are stored. These particles 23 are exposed on the surface 25 formed by the cover layer 22, wherein there is an effect of reducing the adhesion of the surface 25 is ensured by the particles 23 made of plastic. The latter is also retained when the cover layer is subject to wear, since during a removal of the cover layer 22, the particles 23 made of plastic lying in the interior of the matrix 24 are exposed. With progressive wear of the cover layer 22, a subsequent heat treatment can improve the adhesion properties of the worn cover layer 22 again.

FIG. 2 shows how the effect of a reduction in the adhesion of the surface 25 is achieved by a heat treatment. The portion of surface 25 of the topsheet 22 before Wär ^¬ mebehandlung the fracture line is shown on the left. It is noticeable that the particles 23 piercing the surface 25 have a substantially round shape. Right of breakage line, the particles 23a are shown on the surface 25 after the heat treatment. These have a smooth upper surface ^¬. Adjacent particles 23a have ^deformed to such an extent that they have grown together and represent a uniform surface in this area. Overall, there is a lesser part of the surface of the matrix material 24 ^¬ available. Depending on the density of the particles 23a, a substantial sealing of the surface 25 may he ^¬ follow. This can be advantageous depending on the application.

FIG. 3 shows a delivery hopper 30 made of steel. This may for example be arranged at the bottom of a reservoir for powder (not shown). The Innensei- te of the hopper 22 is coated electrochemical ^¬ mixed with a single layer, which corresponds to the position 22 according to FIG. 1 Since the feed hopper 30 is metallic, the sheet 22 can be deposited directly on the inner surface thereof. FIG. 4 shows a tube 40 made of a thermoplastic material. This tube can be used as a conveying line for powder and has inside a layer composite 12 according to Figure 1, which is not shown in detail in Figure 4. The coating process according to the invention is advantageously also suitable for lining longer pipes with the adhesion-reducing layer composite 12 (the process has already been explained in detail above).

Claims

claims

1. Powder-carrying component (11) of a powder conveying system with an adhesion-reducing layer (12), the least zumin- has an adhesion-reducing surface (25) for Availability checked ^¬ supply alternate end topsheet (22), wherein said topsheet

Having a metallic matrix (17) of nickel,

• are embedded in the particles (23) of a plastic which form at least part of the surface (25).

2. Component (11) according to claim 1,

d a d u r c h e c e n c i n e s that

this consists of a metallic material.

3. component (11) according to claim 1,

d a d u r c h e c e n c i n e s that

this consists of a plastic and on this a starting ^¬ position (16) is applied for electroless plating with metal, wherein the starting position

Having a matrix of a synthetic resin,

• in the metallic particles (18) as germs for the

electroless plating are incorporated.

4. component (11) according to claim 3,

d a d u r c h e c e n c i n e s that

the metal particles (18) in the starting position (16) of Pal ^¬ ladium and / or copper and / or nickel and / or iron.

5. Component (11) according to one of the preceding claims, characterized in that the proportion by volume of metallic particles (18) relative to the synthetic resin of the matrix (17) in the starting layer (16) is at least 60 and at most 85%.

6. Component (11) according to one of the preceding claims, characterized in that a

the cover layer (22) has a thickness of at least 5 and at most 15 ym.

7. Component (11) according to one of the preceding claims, characterized in that a

at least the on the surface (25) of the cover layer (22) lie ^¬ ing particles (23) are heat treated from the plastic.

8. Component (11) according to one of the preceding claims, characterized in that a

the particles (23) consist of PTFE.

9. A process for preparing a powder compo- leading te (11) of a powder conveying system with an adhesion ver ^¬ reducing layer (12) with the following step:

• on the surface of the component is chemically or

at least one covering layer (22) providing the adhesion-reducing surface (25) is produced electrochemically, wherein the cover layer (22) has a metallic layer

Matrix (17), in which particles (23) are embedded in a plastic, which form at least part of the surface (25).

10. The method according to claim

characterized,

that the component (11) is made of a plastic and follow ^¬ the step is preceded by the method: On the component (11), a starting layer (16) forming a surface for further coating steps is applied with a matrix of a synthetic resin, metallic particles (18) being incorporated as seeds for a subsequent electroless plating in the matrix.

11. The method according to claim 10,

d a d u r c h e c e n c i n e s that

the topsheet (22) is subjected to a heat treatment by exposing the surface (25) is acted upon with hot air or the component is placed in an oven until the Parti ^¬ angle (23) of plastic on the surface of melted ^¬ the.