Frictional Brake Element for a Friction Brake of a Motor Vehicle, Friction Brake, and Method for Producing a Frictional Brake Element

Abstract

The disclosure relates to a frictional brake element for a friction brake of a motor vehicle, in particular brake disk, having a main element which is manufactured in particular from grey cast iron and which has at least one wear protection layer applied to the main element and at least one intermediate layer situated between the wear protection layer and the main element. It is provided that the intermediate layer is a metallic intermediate layer applied by laser deposition welding.

Claims

1. A friction brake element for a friction brake disk of a motor vehicle, comprising: a main element made of gray cast iron; at least one antiwear layer applied to the main element; and at least one intermediate layer located between the antiwear layer and the main element, wherein the at least one intermediate layer is a metallic intermediate layer applied by laser buildup welding.

2. The friction brake element as claimed in claim 1, wherein the at least one intermediate layer is one of a nickel-based alloy, a cobalt-based alloy, and an iron-based alloy.

3. The friction brake element as claimed in claim 1, wherein the at least one intermediate layer has an at least two-phase microstructure.

4. The friction brake element as claimed in claim 1, wherein each of the respective phases of the at least two-phase microstructure makes up at least 5% by volume of the at least one intermediate layer.

5. The friction brake element as claimed in claim 1, wherein the at least one antiwear layer is an antiwear layer applied by one of thermal spraying on and laser buildup welding to the intermediate layer.

6. The friction brake element as claimed in claim 1, wherein a surface of the at least one intermediate layer facing the at least one antiwear layer has been pretreated thermally.

7. The friction brake element as claimed in claim 1, wherein the at least one antiwear layer is configured as one of ceramic coating and iron-based alloy, the at least one antiwear layer having embedded hard material particles consisting of carbides, oxides, nitrides or borides.

8. The friction brake element as claimed in claim 7, wherein a layer thickness of the at least one intermediate layer is at least twice an average particle size of the hard material particles embedded in the at least one antiwear layer.

9. A friction brake for a motor vehicle, having at least one brake disk and at least one movable brake pad assigned to the brake disk, wherein the brake disk is configured as friction brake element as claimed in claim 1.

10. A process for producing a friction brake element for a friction brake of a motor vehicle, comprising: providing a main element made of gray cast iron; applying at least one metallic intermediate layer by laser buildup welding to the main element; and providing at least one antiwear layer on a side of the at least one metallic intermediate layer opposite the main element.

11. The process as claimed in claim 10, wherein the at least one intermediate layer is applied to the main element in such a way that it has an at least two-phase microstructure.

12. The process as claimed in claim 10, wherein: hard material particles are embedded in the at least one antiwear layer; and the at least one intermediate layer is applied to the main element in such a way that a layer thickness of the at least one intermediate layer is at least twice an average particle size of the hard material particles embedded in the at least one antiwear layer.

Description

[0015] The invention will be illustrated in more detail below with the aid of the drawing. The figures show:

[0016] FIG. 1 an advantageous friction brake element in a simplified perspective depiction,

[0017] FIG. 2 a simplified depiction of a production process for the frictional brake element and

[0018] FIG. 3 a flow diagram to explain the production process.

[0019] FIG. 1 shows, in a simplified perspective depiction, a friction brake element 1 configured as a brake disk 2 for a friction brake, which is not shown in more detail here, of a motor vehicle. The friction brake element 1 has a circular main element 3 made of gray cast iron. A brake disk chamber which is optionally present on the brake disk 2 is not shown in FIG. 1. On each of its two faces, the main element 3 has an annular frictional contact surface 4 which is formed by an antiwear layer 5 of the friction brake element 1. The antiwear layer 5 forms, in correct operation, a frictional contact partner for at least one brake pad or brake lining of the friction brake, which for carrying out a braking operation is pressed against the frictional contact surface 4 to achieve friction braking. The brake disk 2 is usually fixed to a wheel of the motor vehicle for rotation therewith, while the brake pad is fixed to the housing and can be moved only in the direction of the brake disk 2. The relative movement of brake disk 2 and brake pad results, when the brake pad is pressed against the frictional contact surface 4, in abrasion on the friction brake element 1, leading to wear of the friction brake element 1 and to brake dust which enters into the surroundings of the motor vehicle.

[0020] The antiwear layer 5 reduces this wear and increases the abrasion resistance of the friction brake element 1. In particular, the antiwear layer is configured as ceramic coating or as iron-based alloy which has embedded hard material particles consisting of carbides, oxides, nitrides or borides, in order to ensure the abovementioned advantages.

[0021] To ensure reliable adhesion of the antiwear layer 5 to the main element 3, a metallic intermediate layer 6 is provided between the antiwear layer 5 and the main element 3. The intermediate layer 6 is applied by laser buildup welding to the main element 3.

[0022] In this respect, FIG. 2 shows the process of laser buildup welding in a simplified sectional depiction. Here, an outer layer 7 of the main element 3 is heated by a laser beam 8 so that the outer layer 7 melts. At the same time, a supplementary material 9 for producing the metallic intermediate layer as nickel-, cobalt- or iron-based alloy is melted by the laser beam and subsequently mixed with the melted outer layer 7 so that, in particular, a welding bead 10 which forms the intermediate layer 6 is formed.

[0023] The antiwear layer 5 is, in particular, likewise applied by means of laser buildup welding to the intermediate layer 6 produced in this way.

[0024] The metallic intermediate layer 6 is preferably applied to the main element 3 in such a way that it has an at least two-phase microstructure. In particular, the phases each make up at least 5% by volume of the intermediate layer in order to ensure advantageous cracking resistance or fracture toughness of the intermediate layer. As a result of the presence of different phases, a crack which is being formed is stopped or inhibited at the transition from one phase into the adjacent phase, so that crack propagation through the intermediate layer 6 is advantageously prevented.

[0025] FIG. 3 shows an advantageous process for producing the friction brake element 1 with the aid of a flow diagram. In a first step S1, the main element 3 is provided. The main element is, as mentioned above, preferably made of gray cast iron. In a subsequent step S2, at least one face of the main element 3 is preworked or pretreated mechanically or thermally, in particular for roughening or geometric adaptation of the surface to which the metallic intermediate layer 6 is to be applied. The metallic intermediate layer 6 is subsequently applied in a step S3 to the face of the main element 3 by laser buildup welding. In particular, the intermediate layer is a nickel-, cobalt- or iron-based alloy. The substance-to-substance bonding resulting from laser buildup welding ensures that advantageous layer adhesion of the intermediate layer 6 to the main element 3 is achieved. Subsequently, after the intermediate layer 6 has solidified or cooled sufficiently, the intermediate layer 6 is optionally pretreated thermally on its free surface in a step S4, for example by means of laser beam treatment. The antiwear layer 5 is subsequently applied to the intermediate layer 6 in a step S5, in particular by means of laser buildup welding or thermal spraying. As mentioned above, the antiwear layer 5 is, in particular, configured as iron-based alloy comprising carbides, oxides, nitrides or borides to increase the wear resistance, or as ceramic coating.

[0026] The finished friction brake element 1 is subsequently obtained in a step S6. The antiwear layer 5 is optionally after-treated mechanically or thermally, in particular ground, in order to ensure a desired surface roughness for interaction with the brake pad of the friction brake.