DE102012202892B4 - Process for the integration of metallic components in light metal-infiltrated carbon and / or graphite-based semi-finished products and use of the semi-finished products - Google Patents

Abstract

Method for introducing metallic components into carbon and / or graphite-based semi-finished products, characterized by the following steps: a) the materials graphite and / or carbon and at least one metal are processed into components or component components, taking into account the thermal expansion behavior of these materials later contacting surfaces of these materials at a given temperature T (i) have the same geometry; b) the components are brought at least to the temperature T (i), wherein T (i) is always less than the melting temperature of the metallic component with the lowest melting temperature; c) the components are brought together in such a way that the intended surfaces of carbon and / or graphite and metal touch without play or have an integration-related minimal clearance; d) the assembled component or assembly component is infiltrated with a molten metal or alloys whose melting temperature is in the range of T (i).

Description

A method for introducing metallic components into carbon and / or graphite-based semi-finished products is described.

Materials based on graphite or carbon are today usually combined with metallic components with non-positive processes, such as cold pressing or shrinking (SGL Group, brochure Carbon and Graphite as Material for plain bearings, Automotive & Mechanical Applications, 09/2008). At least locally, there is an excess of tension, which may be superimposed by the load case set during use, and thus the load that can be reduced has to be reduced or has to be absorbed at this point with the aid of a material reinforcement. In addition, a locally limited low-tension material combination, for example, with closed metal inserts, especially in the field of undercuts to date production reasons not possible.

As a result, it is not possible to use an optimized combination of materials with a separation of the functions, which means that the full potential of the carbon or graphite materials is not utilized or locally a mechanically induced, increased wear occurs.

The invention relates to a method for introducing metallic components into carbon or graphite-based semi-finished products in order to be able to fulfill locally limited functions and thereby to expand the range of use of the base materials (carbon and / or graphite) and to increase the service life.

• a) Die Werkstoffe Graphit und/oder Kohlenstoff und mindestens ein Metall werden unter Berücksichtigung des thermischen Ausdehnungsverhaltens dieser Materialien zu Bauteilen oder Bauteilkomponenten verarbeitet, wobei die später in Berührung kommenden Oberflächen dieser Materialien bei einer bestimmten Temperatur T(i) die gleiche Geometrie aufweisen.
• b) Die Bauteile werden mindestens auf die Temperatur T(i) gebracht, wobei T(i) stets kleiner ist als die Schmelztemperatur (T_Schmelz) des metallischen Bauteils mit der niedrigsten Schmelztemperatur.
• c) Die Bauteile werden derart zusammengeführt, dass sich die vorgesehenen Flächen von Kohlenstoff- und/oder Graphit und Metall (zum Beispiel Kerne, Ringe, Einlagen und Verstärkungselemente) spielfrei berühren oder integrationsbedingt ein minimales Spiel aufweisen. Das Zusammenführen kann bevorzugt auch unter Einsatz von Druck geschehen.
• d) Das zusammengefügte Bauteil wird, vorzugsweise nach einer thermischen Homogenisierung und ohne zwischenzeitliche Abkühlung, mit einem schmelzflüssigen Metall bevorzugt aus der Gruppe der Nichteisenmetalle (z. B. auf der Basis von Aluminium, Magnesium, Kupfer, Antimon und Zinn) oder deren Legierungen infiltriert, dessen Schmelztemperatur im Bereich von T(i) liegt.

The invention relates to a method for introducing metallic components into carbon and / or graphite-based semi-finished products with the following steps:

• a) The materials graphite and / or carbon and at least one metal are processed taking into account the thermal expansion behavior of these materials to components or component components, the later coming into contact surfaces of these materials at a certain temperature T (i) have the same geometry.
• b) The components are brought at least to the temperature T (i), wherein T (i) is always less than the melting temperature (T _melt ) of the metallic component with the lowest melting temperature.
• c) The components are brought together in such a way that the intended surfaces of carbon and / or graphite and metal (for example cores, rings, inserts and reinforcing elements) touch without play or have an integration-related minimal clearance. The merging can preferably also be done using pressure.
• d) The joined component is, preferably after a thermal homogenization and without interim cooling, preferably infiltrated with a molten metal from the group of non-ferrous metals (eg based on aluminum, magnesium, copper, antimony and tin) or their alloys whose melting temperature is in the range of T (i).

In this case, the joint between carbon and / or graphite and metal is almost stress-free to stress-free, which is surprisingly no material increase.

Furthermore, the introduction of closed metal structures such. As rings in grooves and undercuts possible.

Here are carbons and / or graphites are used, which have an open-porous, contiguous pore structure.

Preferably, steps b and c are also carried out in the reverse order, so it is first brought together and arranged such that merging takes place in the heated state independently or under targeted pressure and then heated, wherein the contact surfaces must not first touch without play.

Step b is preferably carried out in an inert atmosphere or vacuum.

It is preferred that in step d the open porous capillary system of the graphite be completely or almost completely filled with the molten metal. Preferably, this process step is carried out under vacuum.

After cooling, at least in the region of the originally individual carbon- and / or graphite-based semi-finished products, it is particularly preferable to have an inseparable bond at T <T _melt , wherein the boundary surface may contain constituents of the infiltration metal.

In 2 is accordingly as an example an aluminum infiltrated graphite element 1 ( 18 ), which has a joining surface ( 20 ) with a graphite element 2 ( 19 ), wherein the joint gap ( 21 ) is preferably ≦ 2 mm, more preferably ≦ 1 mm.

3 shows an example of a joining of the aluminum-infiltrated graphite element 3 (FIG. 22 ) and the aluminum-infiltrated graphite element 4 ( 25 ). The filling gap filled with aluminum ( 24 ) amounts to ≤ 1 mm. The joint surface ( 23 ) differs from the elements to be joined in color (white).

The carbon- and / or graphite-based semifinished product according to the invention shows, after the metallic infiltration, a change in the material properties and before the coefficient of thermal expansion, depending on the infiltrated metal or metal alloy and on the volume fraction of the infiltrated metal.

In carrying out the embedding of the metal in the graphite material, the component or the component component can also consist of a plurality of carbon and / or graphite elements, wherein the contact points of the graphite elements always have the same constant geometry at constant temperature.

The material of the metallic components to be inserted and the metal-infiltrated carbon and / or graphite-based material preferably have a similar or the same coefficient of thermal expansion, so that more preferably between inserted metallic component and metal-infiltrated carbon and / or graphite material a stress state of 0 to a maximum of 80% the tolerable material strength (tensile or compressive strength) occurs.

Preferably, it is surprisingly possible with the method according to the invention, for example, to introduce hollow channels, ring carriers, bushes, bearings and bearing seats into light metal infiltrated carbon and graphite materials and to permanently bond them to one another insoluble and low in tension. This is possible, above all, under cyclic thermal and / or mechanical loads during the use of constructed in this way material combinations or components.

The light metal-infiltrated carbon and / or graphite-based semi-finished products with integrated metallic components produced by the process according to the invention are preferably used for an internal combustion engine, in particular aircraft, watercraft, land vehicles such as cars, trucks and two-wheeled vehicles as well as engine-operated implements.

In addition, the light metal-infiltrated carbon and / or graphite-based semi-finished products with integrated metallic components produced by the process according to the invention are preferably used as a bearing component.

The following exemplary embodiments describe the invention by way of example.

example 1

A graphite cylinder ( 1 ) with a thermal expansion coefficient TA (G) = 4 × 10 ^-6 K ^-1 , a total height HG = 50 mm ( 2 ) and a diameter D1 = 105 mm ( 3 ) is at a height h = 10 mm ( 4 ) from a front side S ( 5 ) to the diameter D2 = 99.7 mm ( 6 ) turned off. Its open porosity is in the range of 10-25% by volume.

Likewise, a ring made of austenitic cast iron ( 7 ) with a thermal expansion coefficient TA (E) = 8 × 10 ^-6 K ^-1 with a height HE = 7 mm ( 8th ), an outer diameter D3 = 105 mm ( 9 ) and an inner diameter D4 = 99.3 mm ( 10 ) produced.

Finally, a graphite tube ( 11 ), which consists of the same material as the above-described graphite cylinder ( 1 ), with a length of approx. LR = HG - h - HE = 33 mm ( 12 ), an outer diameter D5 = D1 = 105 mm ( 13 ) and an inner diameter D6 = D2 = 99.7 mm ( 14 ) produced.

These three components ( 1 ) 7 ) and ( 11 ) are heated from room temperature (20 ° C) to T = 800 ° C under an inert atmosphere. Due to the thermal expansion of the materials, the diameters reach D2 * = D4 * = D6 * = D (800) = 100 mm.

While maintaining this temperature, the 3 components are put together, an infiltration chamber ( 15 ) and with molten aluminum ( 16 ) infiltrated.

After the infiltration process and after cooling of the entire component, the aluminum-infiltrated graphite material has a coefficient of thermal expansion of about TA (AIG) = 8 × 10 ^-6 K ^-1 due to its composite properties. Its diameter D2 (new) is now about D2 (new) = 99.3 mm. Due to the now same / very similar thermal expansion coefficient of the aluminum-infiltrated graphite and the austenitic cast iron arises at the contact point ( 17 ) Both materials a surprisingly stress-free or low tension connection (voltages due to the connection <80% of the voltage failure). In a final processing step, the final contour of a piston is made from this body. In this case, a groove for receiving a piston ring is introduced into the introduced metal ring (ring carrier).

Example 2

The procedure is as in Example 1, except that for easier assembly and fixing a part of the graphite cylinder ( 1 ) (outside) and part of the graphite tube ( 11 ) (inside) frustoconical ( 17 ) are designed. As a result, a certain self-guidance and self-centering when merging is effected.

Example 3

The procedure is as in Example 1 or 2 and introduced a bearing bush made of titanium with a coefficient of thermal expansion of 8.4 × 10 ^-6 K ^-1 in a infiltrated with aluminum graphite blank and integrally integrated.

LIST OF REFERENCE NUMBERS

1

Graphitzylinder

2

Gesamthöhe HG

3

Durchmesser D1

4

Höhe h

5

Stirnseite S

6

Durchmesser D2

7

Ring

8

Höhe HE

9

Außendurchmesser D3

10

Innendurchmesser D4

11

Graphitrohr

12

Länge LR

13

Außendurchmesser D5

14

Innendurchmesser D6

15

Infiltrationskammer

16

schmelzflüssiges Aluminium

17

Berührstelle beider Werkstoffe

Fig. 2

18

Aluminium infiltriertes Graphitelement 1

19

Aluminium infiltriertes Graphitelement 2

20

Fügeflächen

21

Fügespalt bevorzugt ≤ 2 mm, besonders bevorzugt ≤ 1 mm

Fig. 3

22

Aluminium infiltriertes Graphitelement 3

23

Fügefläche

24

Fügespalt

25

Aluminium infiltriertes Graphitelement 4

Fig. 1

1

graphite cylinder

2

Total height HG

3

Diameter D1

4

Height h

5

Front side S

6

Diameter D2

7

ring

8th

Height HE

9

Outer diameter D3

10

Inner diameter D4

11

graphite tube

12

Length LR

13

Outer diameter D5

14

Inside diameter D6

15

infiltration chamber

16

molten aluminum

17

Touch point of both materials

Fig. 2

18

Aluminum infiltrated graphite element 1

19

Aluminum infiltrated graphite element 2

20

joining surfaces

21

Bonding gap preferably ≤ 2 mm, more preferably ≤ 1 mm

Fig. 3

22

Aluminum infiltrated graphite element 3

23

joining surface

24

joining gap

25

Aluminum infiltrated graphite element 4

Claims (11)

Method for introducing metallic components into carbon and / or graphite-based semi-finished products, characterized by the following steps: a) the materials graphite and / or carbon and at least one metal are processed taking into account the thermal expansion behavior of these materials to components or component components, the later coming into contact surfaces of these materials at a certain temperature T (i) have the same geometry; b) the components are brought at least to the temperature T (i), wherein T (i) is always less than the melting temperature of the metallic component with the lowest melting temperature; c) the components are brought together in such a way that the intended surfaces of carbon and / or graphite and metal touch without play or have an integration-related minimal clearance; d) the assembled component or assembly component is infiltrated with a molten metal or alloys whose melting temperature is in the range of T (i). Method for introducing metallic components into carbon and / or graphite-based semi-finished products, characterized in that the steps b and c are carried out in reverse order, that is, first brought together or arranged such that merging in the heated state independently or under targeted acted upon pressure and then heated, with the contact surfaces must first not touch play. Method for introducing metallic components into carbon and / or graphite-based semi-finished products according to one or more of the preceding claims, characterized in that step b is carried out in an inert atmosphere or vacuum. Method for introducing metallic components into carbon and / or graphite-based semi-finished products according to claim 1, characterized in that in step d, the open-porous capillary system of the graphite is completely or almost completely filled with the molten metal. Method for introducing metallic components into carbon and / or graphite-based semi-finished products according to claim 1, characterized in that in step d the molten metal is selected from the group of non-ferrous metals or their alloys. Method for introducing metallic components into carbon and / or graphite-based semi-finished products according to one or more of the preceding claims, characterized in that after cooling, at least in the region of the originally individual carbon and / or graphite components, there is an inseparable bond at T <T _melt wherein the interface may include constituents of the infiltration metal. Method for introducing metallic components into carbon and / or graphite-based semi-finished products according to one or more of the preceding claims, characterized in that the component made of carbon and / or graphite consists of a plurality of carbon and / or graphite elements, wherein the contact points of the graphite Elements always have the same geometry. Method for introducing metallic components into carbon and / or graphite-based semi-finished products according to one or more of the preceding claims, characterized in that the material of the metallic components to be inserted and the metal-infiltrated carbon and graphite-based material have a similar or the same coefficient of thermal expansion. Method for introducing metallic components into carbon and / or graphite-based semi-finished products according to one or more of the preceding claims, characterized in that hollow channels, ring carriers, bushes, bearings and bearing seats are introduced into light metal-infiltrated carbon and graphite materials and permanently connected to each other insoluble and low stress become. Use of the light metal-infiltrated carbon and / or graphite-based semi-finished products produced according to claims 1 to 9 with integrated metallic components for an internal combustion engine, in particular in aircraft, watercraft, land vehicles such as cars, trucks and two-wheeled vehicles, as well as in engine-powered implements. Use of the light metal-infiltrated carbon and / or graphite-based semi-finished products produced according to claims 1 to 9 with integrated metallic components as bearing component.

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