DE102015219055A1 - Method and coating for protecting a component against corrosion - Google Patents

Abstract

In order to enable improved corrosion protection, it is proposed that a method for corrosion protection comprises applying a coating for corrosion protection by means of a nozzle, wherein the nozzle is moved by means of a robot, and wherein the nozzle moves in accordance with the shaping, in particular elevations and undercuts, of the component becomes.

Description

The invention relates to a method for protecting a component against corrosion according to claim 1. In addition, the invention is concerned with a coating for protecting a component against corrosion according to claim 7.

State of the art

When connecting a plurality of components, in particular sheet metal, there is typically the problem that an existing coating of the components for corrosion protection, with which they are typically factory-fitted, is damaged. The damage is usually done by mechanical action during joining, cutting or reshaping of the component. Of particular concern is the lightweight, which is increasingly realized in the form of mixed construction, since in this case different materials, such as steel, aluminum, magnesium and carbon fiber reinforced plastic (CFRP) by gluing, riveting, welding, etc. are interconnected.

In order nevertheless to ensure adequate corrosion protection, it is known from the prior art to cover the joints of the components joined together generously with a polyvinyl chloride (PVC) paint, which is to form a further insulating layer. However, this approach has several disadvantages. The use of PVC leads to an increase in weight of the component, which is in contradiction to the lightweight construction of the mixed structure. Furthermore, the use of PVC is very costly.

In the following, the term "components" is understood in particular to mean plates for vehicle construction, preferably body construction of vehicles. In this case, the above-mentioned problems occur especially in the wet area, i. in the vehicle outer area, which must be designed to withstand the effects of moisture.

DESCRIPTION OF THE INVENTION: Problem, Solution, Advantages

The object of the present invention is to provide a method and a coating for protecting a component against corrosion, which ensures improved corrosion protection of interconnected components, wherein the use of a PVC coating is to be avoided. Specifically, an increase in weight by ensuring the corrosion protection should be kept to a minimum, while at the same time the coating for corrosion protection should be as robust and resistant as possible. Furthermore, the corrosion protection should be locally applicable. Another object of the invention is that the joined component can be uniformly coated by means of a cathodic dip coating, in particular without causing different color impressions.

According to the invention, it is proposed for this purpose that the method comprises applying a coating to protect the component against corrosion by means of a nozzle, wherein the nozzle is moved by means of a robot, and wherein the nozzle is moved in accordance with the shaping, in particular elevations and undercuts, of the component ,

In particular, the coating is applied by means of robotic technology in the spray method to the component or the surfaces or areas of the component to be coated. The use of robotic technology has the advantage of a free and variable method and pivoting of the nozzle in all angles, so that a conformal coating is possible. The robot technology can thus ensure a coating of any position, in particular, an already pivoted position of the component, in particular the body, can be used after the joining process.

The nozzle is moved according to the shape, in particular the elevations and the undercuts, of the component, so that an approximate 3D coating is made possible. In particular, the contour is traced at an angle of 15 ° to 75 °. This ensures that a uniform layer is deposited. Furthermore, a robot-guided, one-sided accessibility makes it possible to realize different application angles. This allows the reduction of the layer order to the minimum of what is necessary. Furthermore, this is a high-production suitability.

Furthermore, with the method according to the invention, a coating can be applied to places which are difficult to access by means of robot technology, for example on folding edges and in the inner and outer fold area, but in particular in the rockfall area. The advantage of the coating on forming edges is that the protective layers already applied at the factory may be thinner and cracked due to the forming process.

In addition, by means of the method according to the invention, a precise application of the coating to the areas to be protected can take place, similar to spot welding. The coating can thus be applied selectively, exactly where it is needed. Preferably, the method is used exclusively at the locations of a component in which a Coating is necessary. These points are characterized by the fact that the component tends to corrode especially there. The locations preferably include joining elements, their adjacent areas and forming or cutting edges. Furthermore, this includes at least two-layered sheet metal connections, since these process-related damage to the corrosion protection layer can occur. Of the abovementioned points, the method is applied in particular to those which lie in the wet areas of a vehicle.

The method thus makes it possible, in particular, to provide stress-resistant corrosion protection by means of spot-precise and local coating. This leads to a minimal weight increase by the coating, although of course, of course, the application of the method to the entire component is possible.

The thickness of the coating is advantageously only between 500 nanometers to ten micrometers, more preferably between one micrometer to five micrometers, the corrosion protection is guaranteed even with a several nanometers thick layer. Although the coating is thus applied only relatively thin, it is nevertheless formed adherent. By the possibility of applying the coating only locally and selectively, the invention enables an economical and environmentally friendly use, since in principle only a small amount of material is used. Another advantage resulting from this is that this coating does not shimmer through further layers to be applied, for example by means of cathodic dip coating (KTL), or a colored finish, so that no different color impression is produced at the corrosion-protected areas.

Advantageously, the method comprises an atmospheric pressure plasma process or a barrier discharge process for applying a coating to protect against corrosion on the component. The coating is preferably a corrosion protection layer. Both of the above methods provide the advantage that the implementation of the method in a normal air atmosphere is made possible. This eliminates the need for an additional pressure vessel, which is typically needed to create other pressure conditions. The process can thus be easily integrated into an existing production process. In particular, the method according to the invention is suitable for mass production.

A component is preferably at least one metal sheet and / or one joining element for vehicle construction, preferably for the body construction of vehicles, in particular automobiles. In this case, the sheet of sheet materials, including all metals and all organic sheets are to be understood. In particular, sheets are treated in mixed construction by the inventive method.

Preferably, the component has already been treated or processed, so that a corrosion protection layer provided by the factory may have been damaged by the treatment or processing and thus the corrosion protection must be restored. The term "treatment or processing" is to be understood as meaning in particular a joining, a cutting or a forming of the component. A treated or processed component is preferably understood to mean already interconnected metal sheets and / or joining elements. The component is, in particular, the body shell for a vehicle, in particular for an automobile, or parts of it. Under a body shell interconnected sheets are to be understood before they are coated or painted, which form the structure of a vehicle, in particular automobile, above the chassis. For the production of the body shell sheets have been, for example, joined together by gluing, riveting or welding. In particular, the inventive method does not involve the use of PVC. Thus, the coating according to the invention also has no PVC.

Preferably, the application of the coating for corrosion protection after the joining of the component and before painting of the component, in particular the immersion of the component in a dipping bath for cathodic dip painting takes place. In principle, no further coating is necessary in addition to the coatings already applied at the factory prior to the joining process of the component. However, damage to the protective layers can occur during the joining processes of the components. Although these are partially covered by the joining element, but in part also remains a gap. Since the joining element and the materials of the components to be joined mostly consist of different materials, a gap favors not only crevice but also contact corrosion. A similar behavior is also to be observed at the cutting edges of the component materials, since the factory applied coatings, such as zinc, can be damaged here. Although the damaged areas are partially protected by the resulting layer of a coating, in particular a cathodic dip coating, however, between the manufacture of the component, in particular the body shell in which the factory applied protective layers have been damaged, and the painting sometimes considerable periods. However, since the protective layers are only effective in the intact state, can in the Meanwhile, already form corrosion. To prevent this, the inventive method is used between the joining of the component and before painting.

Preferably, the method according to the invention is part of a production process of a bodywork for a vehicle, in particular an automobile. In this case, however, the provision of the method according to the invention after joining ensures, prior to painting the component, that the method fits optimally into the manufacturing process of a body, since in particular the joining elements and their adjacent areas have to be covered in an electrolyte-tight manner for corrosion protection. It follows that the same component areas must be accessible both for joining and for applying the corrosion protection layer, so that the direct succession of joining and the inventive method, the application of the corrosion layer or also the production of a body can be done as efficiently as possible.

In particular, the method according to the invention is applied to areas of the component, in particular the body, which are suitable for being used in the outer and wet regions of a vehicle. Especially in these areas, the thin paint can be damaged by stone chipping, as a result, immediately corrosion occurs and can be further damaged by infiltration of moisture joining elements and body structures.

Optionally, for better adhesion of a coating, in particular cathodic dip coating, on the coating for corrosion protection prior to painting, an intermediate layer, in particular a primer, must be applied. This step can be applied by means of robot technology in a spray process.

In a further embodiment, a gas stream is generated during the process for applying the coating, wherein a, in particular silicon-containing, starting material for the coating is introduced into the gas stream, and wherein by means of the gas stream, the coating-forming constituents are applied to a position to be coated of the component , Under a starting material is to be understood in particular a precursor.

Preferably, the starting material comprises hexamethyldisiloxane and / or tetramethylsilane. In particular, the starting material consists of hexamethyldisiloxane and / or tetramethylsilane.

The generated gas stream typically results from the ignition of a plasma in a nozzle, in particular a plasma nozzle, and the flow of a process gas past the discharge path, so that it is converted into the plasma state. The flow of gas is preferably directed towards the substrate by means of the nozzle, i. of the component, in particular the coated surface of the component held. The constituents of the gas deposit on the substrate as a layer. The process for protecting a component against corrosion is independent of the substrate material, so that a wide variety of substrates can be coated. The substrate or the component to be coated may include, for example, plastics, in particular glass fiber reinforced plastic (GRP) or CFRP. Furthermore, the component may comprise non-metal and metal combinations, for example aluminum, magnesium, steels of all strength groups, etc. Furthermore, the component may consist entirely of one of the aforementioned materials.

The method according to the invention is also suitable for use in the case of service or repair cases in which the coating has to be newly applied. For example, in the case of restoration of an accident vehicle, no re-covering with PVC would have to take place, as is currently the case in the prior art.

A coating is to be understood in particular as a system of layers. These layer systems can preferably be applied as a gradient system. Furthermore, different layer systems can be deposited, which consequently form the coating. Layers for active corrosion protection, such as e.g. Zinc layers and their compounds, and / or layers for passive corrosion protection, i. Coating layers with oxides and / or carbides, for example. Alumina or silica are used to form the coating to protect a component from corrosion.

In particular, not only a starting material but also additives and / or inhibitors for corrosion protection are introduced into the gas stream produced by means of the plasma, which consequently likewise find themselves in the coating for corrosion protection. The additives and / or inhibitors may have different states of aggregation when introduced into the gas stream and be converted into a gaseous phase in the plasma during the coating process or incorporated into the layer as solid particles.

In this case, for example, zinc, cerium, phosphorus and / or boron-containing additives may be mentioned, which may have a share of 1 to 15 atomic percent in the overall layer system.

Furthermore, the invention relates to a coating for protecting a component from corrosion. The coating is designed to prevent corrosion on a vehicle part, in particular a body part of a vehicle, wherein the coating additives or inhibitors for corrosion protection, in particular zinc, cerium, phosphorus and / or boron-containing additives having a preferred proportion of 1 to 15 atomic percent of the coating. Furthermore, the coating is elastic. For this, the coating has polymeric properties. The advantage of such a configuration is that the coating can simulate a thermal expansion of the component without delaminating. This is realized by the fact that the precursor contains oxygen, hydrogen and carbon.

In particular, the coating is applied by a method according to one of claims 1 to 7 on the component. The coating, in particular its thickness, is furthermore preferably designed in such a way that it does not shine through further layers applied thereon, for example a lacquer layer through a cathodic or other lacquer process, so that overall a uniform color impression of the component arises.

Brief description of the drawings

They show schematically:

1 a flow diagram of a method according to the invention;

2 a flow diagram of a method for producing a body comprising a method according to the invention; and

3 a longitudinal section of an apparatus for performing a method according to the invention.

Preferred embodiments of the invention

1 shows a flowchart of a method according to the invention ( 100 ) to protect a component from corrosion. First, a coating is applied to the component for protection against corrosion. For this purpose, an atmospheric pressure plasma coating method is used, according to which a plasma is generated within a plasma nozzle in which there is a working gas by means of a high-voltage discharge ( 10 ). A process gas is conducted past the discharge path in the vicinity of the nozzle head and transferred to the plasma state. In this way, a gas flow is generated ( 11 ). In the gas stream, a precursor is introduced ( 12 ). Furthermore, additives and inhibitors for corrosion protection are introduced into the gas stream ( 13 ). The gas flow is held by means of a robot of the nozzle in the direction of the point to be coated of the component ( 14 ). The plasma comprising the precursor and the additives and inhibitors reaches the surface of the site to be coated and is deposited as a coating for corrosion protection.

In 2 is a flowchart of a method ( 200 ) for producing a bodywork for an automobile comprising a method according to the invention ( 100 ). The first step is the joining of a body shell ( 21 ), which includes the joining of sheets. Before the body shell of a KTL is subjected, the inventive method ( 100 ) to 1 performed, in particular at the points of the body shell, which tend by the previously performed Joining step especially for corrosion.

As the next step, an intermediate layer, in particular a primer, can be applied to the coating as a corrosion protection layer ( 22 ). In particular, the intermediate layer is applied by means of robot technology in a spray process. This step serves to better adhesion of a coating on the corrosion layer. Subsequently, the body shell is immersed in a cathodic dip bath ( 23 ), after which furthermore a final finish for the completion of the body can take place.

3 shows a longitudinal section of a device ( 300 ) for carrying out a method according to the invention ( 100 ). The device ( 300 ) is configured to carry out an atmospheric pressure plasma coating process. For this purpose, it comprises a plasma nozzle ( 31 ) for the production of a plasma. Parts of the inner surface of the plasma nozzle ( 31 ) are covered with a dielectric ( 32 ) Mistake. The plasma nozzle ( 31 ) comprises an electrode ( 38 ) powered by a power supply ( 37 ) is supplied with electricity. Into the plasma nozzle ( 31 ) is replaced by a working gas supply ( 36 ) a working gas ( 35 ) introduced. Through a hole aperture ( 34 ) at the level of the electrode ( 38 ) within the plasma nozzle ( 31 ) the working gas ( 35 ) mixed turbulently. Due to a high-voltage discharge, an arc ( 33 ), the working gas ( 35 ) and thus generates a plasma. Process gas ( 40 ) is in an outside of the plasma nozzle ( 31 ) arranged evaporator ( 41 ) in the gaseous state and at the nozzle head ( 39 ) of the plasma nozzle ( 31 ) passed by. As a result, the process gas ( 40 ) brought into the plasma state. A gas stream ( 42 ) in the direction of the component to be coated ( 43 ) arises. The device ( 300 ) is in a direction of travel ( 45 ) at a distance to the coating surface over the component ( 43 ) hazards. The constituents of the gas stream ( 42 ) divide on the surface of the component ( 43 ) as a coating ( 44 ) for corrosion protection.

LIST OF REFERENCE NUMBERS

100

 Inventive method

10

 Generating a plasma

11

 Generating a gas stream

12

 Introducing a precursor into the gas stream

13

 Introducing additives and inhibitors into the gas stream

14

 Directing the gas flow onto the part of the component to be coated by means of a nozzle moved by a robot

200

 Manufacturing process of a body

21

 Joining a body shell

22

 Applying a primer

23

 Carrying out a cathodic dip painting

300

 Apparatus for carrying out a method according to the invention

31

 plasma nozzle

32

 dielectric

33

 Electric arc

34

 pinhole aperture

35

 working gas

36

 Working gas supply

37

 power

38

 electrode

39

 nozzle head

40

 process gas

41

 Evaporator

42

 gas flow

43

 component

44

 coating

45

 Direction of travel of the device

Claims (8)

Procedure ( 100 ) for protecting a component ( 43 ) from corrosion, the method comprising applying a coating ( 44 ) for the protection of the component ( 43 ) against corrosion by means of a nozzle ( 31 ), wherein the nozzle ( 31 ) is moved by means of a robot, characterized in that the nozzle ( 31 ) according to the shape, in particular elevations and undercuts, of the component ( 43 ) is moved. Procedure ( 100 ) for protecting a component ( 43 ) according to claim 1, characterized in that the method comprises an atmospheric pressure plasma method or a barrier discharge method for applying a coating ( 44 ) for protection against corrosion on the component ( 43 ). Procedure ( 100 ) for protecting a component ( 43 ) from corrosion according to one of claims 1 or 2, characterized in that the process ( 100 ) after joining the component ( 21 ) and before painting the component ( 43 ), in particular immersion of the component in a dipping bath for cathodic dip painting ( 23 ), is carried out. Procedure ( 100 ) for protecting a component ( 43 ) against corrosion according to one of the preceding claims, characterized in that during the process for applying the coating ( 44 ) a gas stream is generated ( 11 ), wherein a, in particular silicon-containing, starting material for the coating ( 44 ) in the gas stream ( 42 ) is introduced, and wherein by means of the gas stream ( 42 ) the coating ( 44 ) constituents on a part of the component to be coated ( 43 ) are applied. Procedure ( 100 ) for protecting a component ( 43 ) from corrosion according to claim 4, characterized in that the starting material comprises hexamethyldisiloxane and / or tetramethylsilane. HMDSO, TMS Procedure ( 100 ) for protecting a component ( 43 ) from corrosion according to one of claims 4 or 5, characterized in that additives and / or inhibitors for corrosion protection are introduced into the gas stream ( 13 ). Coating ( 44 ) for protecting a component ( 43 ) from corrosion, characterized in that the coating ( 44 ) is designed to prevent corrosion on a vehicle part, in particular a body part of a vehicle, wherein the coating additives and / or inhibitors for corrosion protection, in particular zinc, cerium, phosphorus and / or boron-containing additives having a respective preferred proportion from 1 to 15 atomic percent of the coating ( 44 ), the coating ( 44 ) is designed to be elastic about a thermal expansion of the component ( 43 ). Coating ( 44 ) for protecting a component ( 43 ) from corrosion according to claim 7, characterized in that the coating ( 44 ) by a process ( 100 ) according to one of claims 1 to 6 on the component ( 43 ) is applied.

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