WO2012113426A1

WO2012113426A1 - Method of joining a component composed of a carbon fibre-reinforced composite to a component comprised of a metal and bonding arrangement of such components

Info

Publication number: WO2012113426A1
Application number: PCT/EP2011/006127
Authority: WO
Inventors: Stephan Klose
Original assignee: Daimler Ag
Priority date: 2011-02-25
Filing date: 2011-12-07
Publication date: 2012-08-30
Also published as: DE102011012319A1

Abstract

The invention relates to a method of joining a first component composed of a carbon fibre-reinforced composite to a second component composed of a metal, in which a join region of the first component is provided before joining with a corrosion protection layer (42) for protection against electrochemical contact corrosion, where the corrosion protection layer (42) is applied by thermal spraying and an electric insulator or a metal which is electrochemically more noble than the metal of the second component is used for the corrosion protection layer (42).

Description

METHOD FOR ADDING A COMPONENT FROM A CARBON FIBER REINFORCED

COMPOSITE COMPOSITE COMPRISING A COMPONENT OF A METAL AND CONNECTING ARRANGEMENT OF SUCH COMPONENTS

The invention relates to a method for joining a first component made of a carbon fiber reinforced composite material with a second component made of a metal according to the preamble of patent claim 1 and a connection arrangement of such components according to the preamble of patent claim 5.

In the course of modern lightweight construction efforts, carbon fiber-reinforced composite materials are increasingly being used in motor vehicle construction. Such parts find, for example, for exterior skins or the like use and must then be joined with metallic components, such as support parts of the motor vehicle or the like. Due to the conductivity of the carbon fiber may form a local element in the contact area between such components. This is particularly problematic when joining carbon fiber reinforced plastics with aluminum or magnesium based light metal components. Electrochemically, the carbon in the composite component is in fact more noble than the respective metal of the component connected to it, which can lead to electrochemical contact corrosion on the part of the metallic component. Even steel components may be subject to such contact corrosion when in contact with carbon fibers.

For such an electrochemical corrosion process to expire, the penetration of moisture and a slightly acidic or alkaline environment is necessary. To protect against corrosion, therefore, nowadays the contact points between

Metal components and carbon fiber reinforced components usually sealed accordingly. This can be done for example by cathodic dip painting of the metallic component. It is also known to seal the components by adhesive application against each other. Another known from the prior art method for preventing contact corrosion is the joining area of a

carbon fiber reinforced component prior to joining with a glass fiber reinforced layer laminate. This is electrically non-conductive, so that the contact corrosion is prevented.

The known methods have the disadvantage that the order of the

Corrosion protection is either expensive, such as in the case of lamination with glass fiber, or the corrosion protection layer does not have high mechanical resistance, so that it can lead to unwanted corrosion processes in case of damage to this layer again.

From DE 102009056672 A1 a method for the reduction of corrosion at an interface is known, which is formed between a magnesium part and a fixing part of a further metal. For this purpose, a corrosion protection material is to be cold sprayed onto the interface. The corrosion protection material comprises at least magnesium, wherein the corrosion protection material is substantially the same as that for the magnesium part.

The present invention is therefore based on the object, a method according to the preamble of claim 1 and a connection arrangement according to the

To provide preamble of claim 5, which is a simple and

allow corrosion-proof joining of carbon fiber reinforced components with metallic components.

This object is achieved by a method having the features of patent claim 1 and by a connection arrangement having the features of patent claim 5.

In such a method for joining a first component of a

Carbon fiber reinforced composite material with a second component made of a metal, a joining region of the first component is provided before joining with a corrosion layer for protection against electrochemical contact corrosion. According to the invention, it is provided that the corrosion protection layer is used up by thermal spraying. By thermal spraying particularly dense and non-porous and at the same time well-adhering corrosion protection layers can be applied in a technically simple manner, which provide reliable protection against electrochemical contact corrosion, even in mechanically loaded joint areas. In addition, it is provided that for the anticorrosion layer, an electrical insulator or a metal, which is electrochemically nobler than the metal of the second component, is used. Ceramics based on chromium oxide, aluminum oxide or titanium oxide, which are easy to apply by conventional spraying methods, are particularly suitable for this purpose. In particular, the use of nickel, tin or alloys thereof is expedient for metallic coatings. The latter metals are particularly suitable for the corrosion protection of aluminum or magnesium components, but are also suitable for use on steel components.

The inventive method is inexpensive and fast in its implementation can be automated very well. As a result, a quick and cheap way is provided to protect the contact areas between metal parts and carbon fiber reinforced plastic long term reliable against contact corrosion.

For applying the corrosion protection layer, all conventional thermal

Spray method can be used. In particular, however, is the cold gas spraying and especially the cold gas high-speed flame spraying. Here, the spray particles, which are usually provided in the form of a wire, a powder or the like, accelerated in a relatively cold carrier gas of a few 100 ° C temperature to high speeds. When the particles strike the component, the particles, which are not melted or only partially melted, form a dense and low-pore layer.

Cohesion and adhesion of the sprayed layer is produced by the high genetic energy of the particles in the highly accelerated carrier gas flow, which ensures plastic deformation and the resulting local heat release upon impact of the sprayed particles. By using noble gases such as argon or other inert gases as the carrier gas, oxidation or phase conversions in the spray material can be avoided particularly reliably. Due to the only local heating due to the kinetic energy of the spray particles and the low carrier gas temperature, the matrix of carbon fiber-based material is hardly affected, so that there is a high quality sprayed layer, which does not adversely affect the durability of the carbon fiber reinforced component.

The invention further relates to a connection arrangement of a first component made of a carbon fiber reinforced composite material with a second component made of a metal, wherein the joining region of the components, a corrosion protection layer for protection against electrochemical contact corrosion is attached. According to the invention is provided that the corrosion protection layer is applied by thermal spraying on the first component and that the corrosion protection layer of an electrical insulator or a metal which is electrochemically nobler than the metal of the second component consists. As already explained with reference to the method, this results in a particularly dense, well-adhering and low-pore corrosion protection layer, which adheres to the carbon fiber reinforced component even under mechanical stress of the connection assembly and prevents the penetration of moisture and electrochemical contact corrosion particularly reliable.

Suitable materials for the anticorrosion layer are, in particular, electrical insulators, in particular ceramics based on chromium oxide, aluminum oxide or titanium oxide, and also metals which are more noble than the metal of the second component. The term noble is to be understood here that the metal of the coating material has a more positive normal potential than the material of the second component. When using aluminum or magnesium components which have a normal potential of -1.66 V or -2.36 V, therefore, in particular nickel with a normal potential of -0.25 V or tin with a normal potential of -0.1 is suitable V. The two metals mentioned are also suitable for coating steels (normal potential iron: -0.44 V). In order to compensate for different coefficients of thermal expansion of the matrix material of the carbon-fiber-reinforced composite component and of the sprayed layer, it is optionally also possible to inject interlayers with adapted thermal expansion coefficients.

The corrosion protection layer can be applied by any spraying method, but preferably the cold gas spraying, in particular by the cold gas high-speed flame spraying. In detail, the advantages of these spray techniques were already explained in the discussion of the process.

In the following the invention and its embodiments will be explained in more detail with reference to the drawing. Show it:

Figure 1 is a schematic sectional view through a connection arrangement of a carbon fiber reinforced component and a metallic component according to the prior art.

Fig. 2 shows the corrosion pattern of such a connection arrangement according to the

Prior art after performing a VDA changeover test; Fig. 3 is a schematic representation of the process flow in the manufacture of an embodiment of an inventive

Connecting arrangement according to an embodiment of a

inventive method;

4 is a schematic representation of the processes during

High velocity flame spraying.

In order to produce a connection arrangement of a carbon fiber-reinforced component 12 with a prior art aluminum component 14, a glass fiber reinforced plastic layer 18 is first applied to a surface 20 of the carbon fiber reinforced component 12 in the joining region 16 between the components 12, 14. The glass-fiber-reinforced cover layer, which can be fastened for example by lamination, forms an electrical barrier between the components 12, 14 and thus prevents electrochemical contact corrosion. The components 12, 14 are screwed in the sequence with a screw 22, wherein also the support area 24 of the

Screw head 26 is electrochemically isolated by a glass fiber layer 18. In order to prevent the penetration of moisture between the components, a seam seal 28 is still attached in the edge region of the joining region 16, so that the contact corrosion is avoided particularly reliably. In particular, can be prevented by the penetration of moisture into the threaded portion of the screw 22 here.

Fig. 2 shows on the left side typical corrosion images of unprotected connection arrangements between carbon fiber reinforced components and aluminum components, with the top left the connection by the use of blind rivets made of AlMg 2.5 with rivet mandrels made of chromium-nickel steel and bottom left through the use of steel rivets. In both cases, traces of corrosion 30 are clearly visible. As can be seen from the illustrations shown on the right side, such traces of corrosion 30 are reliably avoided by the use of glass fiber cover layers 18. A disadvantage of the production of such connection assembly 10, however, is the high cost. The joining of carbon fiber reinforced components 12 with aluminum components 14 is therefore very time consuming and costly according to the prior art.

In order to simplify the joining of such components, the method shown schematically in FIG. 3 can be used. Here, the joining area of a Aluminum component, which is to be joined with a carbon fiber reinforced component, provided with a thermally sprayed protective layer. In a first method step S10, a substrate pretreatment takes place in the joining region of the aluminum part. For this purpose, the component is degreased and the surface thereof is optionally roughened by sandblasting. In this case, an average roughness R _A of 4.5 to 5 micrometers or an average roughness R _z of 25 to 30 micrometers is ideally aimed for.

In the following method step S12, an area of the area to be coated is not to be coated

Masked component, whereupon in step S14, the actual coating is carried out by thermal spraying. For this purpose, conventional spraying methods can be used, wherein the cold gas high-speed flame spraying is particularly expedient. For this purpose, the coating material in the form of a wire, powder of a rod or a cord is supplied in a spray gun 32 and at least partially melted in an energy source 34, for example a flame, an arc or a plasma. In a carrier gas stream 36, the particles 38 thus obtained are accelerated toward the surface 40 to be coated.

Due to the kinetic energy of the particles 38 they deform on impact with the surface 40, resulting in a local heat release. As a result, both the particles 38 and the material 40 are locally melted, resulting in a dense, well-adhering and largely non-porous spray layer 42. By the

Use in natural gases such as argon as the carrier gas, an oxidation or phase change of the spray material can be avoided when applied. The low application temperatures simultaneously avoid damage to the matrix of the carbon fiber reinforced component. Suitable materials for application are metals which have a more positive normal potential in the electrochemical voltage series - ie are more noble than the material of the metallic component to be coated. For aluminum components are particularly suitable nickel or tin. Ceramics, for example on the basis of titanium oxides, chromium oxides or aluminum oxides can also be used, so as to ensure complete electrical insulation of the

Aluminum component to achieve.

After the thermal spraying has been carried out, a further treatment can be carried out in method step S16. This can be thermal or mechanical

be carried out, for example by grinding, polishing, remelting or laser structuring, so as to achieve the desired surface properties in the field of Adjust coating 42. A combination of the mentioned methods is of course possible.

In order to achieve a particularly good durability, a polymer seal can also be applied to the coating in the following method step S20.

Overall, a particularly flexible and cost-effective due to the high degree of automation to be applied coating for reliable corrosion protection of the aluminum component is created. The layers are highly compact and therefore show no setting behavior and at the same time a very good adhesion. Between the

Coating 42 and the surface 40 of the aluminum component can optionally be sprayed with an intermediate layer so as to possibly still existing

Differences in the thermal expansion coefficients of the different

Compensate materials.

LIST OF REFERENCE NUMBERS

10 connection arrangement

12 component

14 component

16 joining area

18 plastic layer

20 surface

22 screw

24 circulation area

26 screw head

28 seam sealing

30 traces of corrosion

32 spray gun

34 energy source

36 carrier gas flow

38 particles

40 surface

42 sprayed layer

R _{A center} roughness

R _z roughness

Claims

claims

Method for joining a first component

from a carbon fiber reinforced composite material

with a second component made of a metal,

in which a joining region of the first component before joining with a

Corrosion protection layer (42) is provided for protection against electrochemical contact corrosion,

characterized,

in that the corrosion protection layer (42) is applied by thermal spraying, that an electrical insulator or a metal, which is more noble than the metal of the second component, is used for the anticorrosion layer (42).

Method according to claim 1,

characterized in that

for the anticorrosion layer (42) a ceramic, in particular chromium oxide, aluminum oxide or titanium oxide, is used.

Method according to claim 1,

characterized in that

for the anticorrosion layer (42), nickel, tin or an alloy thereof is used.

Method according to one of claims 1 to 3,

characterized in that

the corrosion protection layer (42) by cold gas spraying, in particular by

Cold gas high velocity flame spraying is applied.

5. Connection arrangement of a first component

from a carbon fiber reinforced composite material

with a second component made of a metal,

in which in the joining region of the components a corrosion protection layer (42) for protection against electrochemical contact corrosion is attached,

characterized,

the corrosion protection layer (42) is applied to the first component by thermal spraying,

in that the corrosion protection layer (42) consists of an electrical insulator or a metal, which is more noble electrochemically than the metal of the second component.

6. Connecting arrangement according to claim 5,

characterized in that

the corrosion protection layer (42) consists of a ceramic, in particular chromium oxide, aluminum oxide or titanium oxide.

7. Connecting arrangement according to claim 5,

characterized in that

the anticorrosion layer (42) is nickel, tin or an alloy thereof.

8. Connecting arrangement according to one of claims 5 to 7,

characterized in that

the corrosion protection layer (42) is applied by cold gas spraying, in particular by cold gas high-velocity flame spraying.