Brake disc, motor vehicle and method for producing a brake disc

Abstract

The invention relates to a brake disc (10) comprising a base body (12) which is coated with at least an intermediate layer (14) and a friction layer (16) covering the intermediate layer (14) on the outside, wherein at least one of the layers (14, 16) has been applied to the main body (12) by means of laser cladding using nitrogen as a shielding gas.

Description

[0001] 24-2153

[0002] 1

[0003] brake disc, motor vehicle and method for manufacturing a brake disc

[0004] The invention relates to a brake disc, a motor vehicle and a method for manufacturing a brake disc.

[0005] From DE 20 2023 002 714 U1, a device for producing a coated workpiece by applying a coating to at least one surface of the workpiece using laser radiation is known. Argon is used as a shielding gas, forming a protective gas bell that encloses a hot area of ​​interaction between laser beams and a coating material and prevents oxidation of the coating material.

[0006] Furthermore, a production plant for forming a processing powder is known from DE 202024 101 243 U1. The production plant is configured to provide and atomize a master alloy. The master alloy is atomized to form the processing powder. The processing powder comprises at least one reaction former and one reactant, which are configured to form at least one ceramic composite.

[0007] Furthermore, WO 2023 / 152014 A1 discloses a laser cladding process for producing coating layers on opposing surfaces of a component. On each surface, a powdered filler material is directed along a helical processing trajectory onto the respective surface. The filler material and the component are moved along the processing trajectory by means of 24-2153

[0008] 2 of a laser beam is heated so that the filler material bonds with the component upon contact with the respective surface.

[0009] The object of the present invention is to provide a solution that enables the production of a brake disc with a particularly long service life.

[0010] This problem is solved according to the invention by the subject matter of the independent claims. Further possible embodiments of the invention are disclosed in the dependent claims, the description, and the figures. Features, advantages, and possible embodiments set forth in the description for one of the subject matter of the independent claims are to be regarded, at least analogously, as features, advantages, and possible embodiments of the respective subject matter of the other independent claims, as well as of any possible combination of the subject matter of the independent claims, optionally in conjunction with one or more of the dependent claims.

[0011] The invention relates to a brake disc, in particular for a motor vehicle, especially a passenger car. Alternatively, the brake disc can be designed for use in an aircraft or in an electric motor brake, for example in elevators. The brake disc is the wheel-side part of a disc brake, against which brake pads attached to a brake caliper act to slow the rotation of the brake disc for braking the motor vehicle. The brake disc is designed to be point-symmetrical about the axle center, and in particular circular. The brake disc has a friction surface which can be brought into contact with at least one brake pad for braking the motor vehicle.By braking the brake disc due to frictional contact between the brake disc and the at least one brake pad, an axle of the motor vehicle, which is rotationally fixed to at least one wheel and rotationally fixed to the brake disc, can be braked. The brake disc comprises a base body coated with at least one intermediate layer and a friction layer covering the intermediate layers on the outside. The base body is thus coated with an at least two-layer system consisting of the at least one intermediate layer and the friction layer. The friction layer provides the friction surface of the brake disc. This means that, for braking the motor vehicle, the at least one brake pad contacts the friction layer of the brake disc 24-2153.

[0012] 3. It is intended that at least one of the layers, and thus at least one intermediate layer and / or the friction layer, has been applied to the base body by laser cladding with nitrogen as a shielding gas. That the at least one layer has been applied to the base body by laser cladding can be recognized by the structure of this layer. Laser cladding is a type of cladding process in which the layer is applied to the base body by melting and simultaneously depositing a coating material. In laser cladding, a high-power laser, in particular a diode laser or fiber laser, serves as the heat source. In laser cladding, a surface to be coated is heated and, if necessary, locally melted by means of at least one laser beam. At the same time, the coating material in powder form is sprayed onto the heated surface with an inert gas mixture.In the heated areas of the surface to be coated, the coating material powder melts and bonds with the surface. In the brake disc according to the invention, the powdered coating material is directed onto the substrate using nitrogen as a protective gas. The use of nitrogen as a protective gas causes the coating material to solidify under a nitrogen atmosphere, thereby generating intrinsically or in-situ hardening nitrides in this layer, particularly near the surface. A nitride is a chemical compound of an element with nitrogen in the form of triply negatively charged anions. Nitrogen can be used both as a protective gas and as a carrier gas for the powdered coating material. These nitrides ensure a particularly high hardness of this layer. Consequently, a particularly long service life of the brake disc can be achieved.The fact that nitrogen was used as a shielding gas during the laser cladding of this layer can be particularly well identified by the nitrides formed in the layer.

[0013] In a possible further development of the invention, the intermediate layer is applied to the base body by means of laser cladding with nitrogen as a shielding gas, whereby the intermediate layer exhibits nitrides, at least in the immediate vicinity of an outer surface facing the friction layer. In other words, laser cladding with nitrogen as a shielding gas has been used to apply the intermediate layer to the base body or to a further underlying intermediate layer. Due to the use of nitrogen as a shielding gas, 24-2153

[0014] 4. Nitrides form within the intermediate layer, particularly near its outer surface. This near-surface nitriding of the intermediate layer enables particularly easy application and secure adhesion of the friction layer to this intermediate layer.

[0015] In a further possible embodiment of the invention, at least one of the layers comprises titanium nitride and / or chromium nitride and / or iron nitride, in particular tetrairon nitride, and / or aluminum nitride. The respective nitrides are therefore metallic nitrides, which can also be referred to as metal nitrides. Metallic nitrides are generally inclusion compounds and form very hard crystals. These very hard crystal-forming metal nitrides thus enable a particularly high hardness of the layer containing these metal nitrides.

[0016] In a further possible embodiment of the invention, the friction layer additionally comprises at least one hard material, in particular a carbide or corundum. Hard materials are characterized by particularly high hardness. Carbides are binary chemical compounds consisting of an element and carbon. In particular, the hard material is a metallic carbide or a metallic carbide. Metallic carbides exhibit particularly high mechanical and thermal stability as well as particularly high melting points. In particular, the carbides are titanium carbide and / or silicon carbide and / or tungsten carbide and / or nickel carbide and / or iron carbide. Corundum is a mineral from the mineral class of oxides and hydroxides. In particular, corundum is aluminum oxide. Corundum exhibits particularly high hardness.By using at least one hard material in the friction layer, the friction layer has a particularly high hardness, which means that when the brake disc is used as intended, the friction layer is subject to very little wear and very little abrasion.

[0017] In another possible embodiment of the invention, the base body comprises a gray cast iron alloy. In particular, the base body is made of gray cast iron. Gray cast iron has a high melting point as well as particularly good heat storage and damping properties. Furthermore, gray cast iron 24-2153

[0018] 5. They are particularly well cast and particularly easy to machine. Alternatively or additionally, the base body can be made of steel and / or stainless steel and / or aluminum.

[0019] The invention further relates to a motor vehicle with a brake disc, as already described in connection with the brake disc according to the invention. The motor vehicle can further have a brake caliper associated with this brake disc, which is configured to apply at least one, and in particular two, brake pads to the brake disc for braking the motor vehicle. The brake caliper can be configured to apply the brake pads to the brake disc from axially opposite sides. Due to the particularly wear-resistant design of the brake disc, the brake disc has a particularly long service life.

[0020] The invention further relates to a method for manufacturing a brake disc, in particular a brake disc for a motor vehicle. Specifically, the method for manufacturing a brake disc is used as already described in connection with the brake disc according to the invention. In this method, a base body of the brake disc is coated with at least one intermediate layer and a friction layer covering the intermediate layer on the outside. At least one of these layers is applied to the base body by laser cladding with nitrogen as a shielding gas. By using nitrogen as a shielding gas in laser cladding, it is possible to achieve the in-situ formation of nitrides in the layer thus produced. These nitrides result in a particularly high hardness of this layer.The process thus enables the layer applied to the base body to have a particularly high hardness and consequently a particularly high resistance.

[0021] In a possible further development of the process, it is envisaged that the intermediate layer is applied to the base body by laser cladding with nitrogen as a shielding gas, whereby the intermediate layer exhibits nitrides, at least in the immediate vicinity of an outer surface facing the friction layer. These nitrides in the intermediate layer enable the intermediate layer to possess particularly high hardness, at least in the immediate vicinity of its outer surface. This, in turn, enables the intermediate layer to be particularly resistant to friction when the friction layer is applied to the intermediate layer or when another intermediate layer is applied to this intermediate layer. 24-2153

[0022] 6. The geometry of the intermediate layer is minimally altered or damaged, resulting in a particularly uniform layer thickness for each layer on the base body. Furthermore, the design of the intermediate layer is highly reproducible, as the risk of alteration during the application of the friction layer or another intermediate layer is minimal.

[0023] In a further possible embodiment of the invention, the friction layer is applied to the intermediate layer by means of cold gas spraying. In particular, nitrogen is also used in the cold gas spraying process to apply the coating material for the friction layer to the intermediate layer. Cold gas spraying is a coating process in which the coating material, in powder form, is applied to a substrate at very high speed. For this purpose, a process gas, especially nitrogen, heated to a few hundred degrees, is accelerated to supersonic speed by expansion in a Laval nozzle, and then particles of the powdered coating material are injected into the gas jet. This accelerates the particles to such a high speed that they form a dense and firmly adhering layer upon impact with the substrate, even without prior melting or deposition.If the intermediate layer, onto which the friction layer is applied during cold gas spraying, contains nitrides near the surface, then the risk of damage to the intermediate layer due to particle impact during cold gas spraying is particularly low. If nitrogen is used as the process gas or shielding gas for both the laser cladding of the intermediate layer and the cold gas spraying, then a production line for manufacturing the brake disc can be designed very simply, since only nitrogen, and not various gases, needs to be provided as process gases or shielding gases. Furthermore, nitrogen is particularly cost-effective and environmentally friendly.

[0024] In an alternative possible embodiment, the friction layer is applied to the intermediate layer by laser cladding with nitrogen as a shielding gas. In particular, it is possible that both the intermediate layer and the friction layer are each applied by laser cladding using nitrogen 24-2153.

[0025] 7. A protective gas has been applied to the base material. This makes manufacturing the brake disc particularly simple, as the intermediate layer and the friction layer are applied using the same process. Furthermore, applying the friction layer by laser cladding using nitrogen as a protective gas allows nitrides to form in the friction layer, especially near the surface. This results in a particularly hard friction layer, making it extremely wear-resistant during operation and generating very little abrasion when the brake disc is used.

[0026] Further features of the invention may become apparent from the claims, the figures, and the description of the figures. The features and combinations of features mentioned above in the description, as well as the features and combinations of features shown below in the description of the figures and / or in the figures themselves, can be used not only in the combinations specified, but also in other combinations or on their own, without departing from the scope of the invention.

[0027] The drawing shows in:

[0028] Fig. 1 shows a schematic sectional view of a section of a brake disc, which comprises a base body coated with an intermediate layer and a friction layer; and

[0029] Fig. 2 shows a schematic side view of the base body, which is coated with the intermediate layer as part of a laser cladding process.

[0030] In the figures, identical and functionally equivalent elements are provided with the same reference symbols.

[0031] Figure 1 shows a schematic sectional view of a brake disc 10 for a motor vehicle. The brake disc 10 comprises a base body 12, which in this case is coated with a two-layer system. This means that the base body 12 is coated with an intermediate layer 14, which in turn is covered on the outside by a friction layer 16. In this case, the base body 12 is made of 24-2153

[0032] 8 is made of a gray cast iron alloy, and the friction layer 16 comprises at least one hard material, in particular a carbide or a corundum. It is provided that the intermediate layer 14 and / or the friction layer 16 are applied by laser cladding using nitrogen as a shielding gas. During the application of the respective layer by laser cladding using nitrogen as a shielding gas, nitrides, in particular metal nitrides, form in this layer. These nitrides form particularly near the surface of the respective layer, especially in the vicinity of an outer surface of the respective layer. It is provided that titanium nitride and / or chromium nitride and / or iron nitride, in particular tetrairon nitride, and / or aluminum nitride form in the respective layer, which has been applied by laser cladding using nitrogen as a shielding gas.

[0033] Figure 2 shows a schematic side view illustrating how the intermediate layer 14 is applied to the base body 12 using nitrogen as a shielding gas in a laser cladding process. Figure 2 shows that a laser beam 20 and a powder jet 22, which in this case surrounds the laser beam 20 in a ring-like fashion, are directed onto a surface 24 of the base body 12 to be coated by means of a nozzle 18 of a laser cladding device. The powder jet 22 comprises powdered coating material for producing the intermediate layer 14. This powdered coating material can be atomized in a nitrogen stream. Nitrogen can thus be used both for transporting the powdered coating material and for creating a shielding gas atmosphere in the region of the surface 24 of the base body 12, towards which the laser beam 20 and the powder jet 22 are directed.After the intermediate layer 14 has been applied to the base body 12, the friction layer 16 can be applied to the intermediate layer 14 either in a further laser cladding process using nitrogen as the process gas or in a cold gas spraying process. During the laser cladding of the respective layer, the melt pool solidifies under a nitrogen protective gas atmosphere. This results in the formation of near-surface nitrides, particularly in the melt pool. In addition to regulating the powder jet 22 and protecting the melt pool formed on the base body 12 from oxidation, the nitrogen can also be used to protect and cool the laser hardware of the laser cladding device 24-2153.

[0034] 9. By using nitrogen for both the application of the intermediate layer 14 and the application of the friction layer 16, regardless of whether cold gas spraying or laser cladding is used for the friction layer 16, it is possible to coat the brake disc 10 using a device comprising only a single nitrogen-carrying gas system. In particular, nitrogen of a purity class of at least 2.0, and especially nitrogen of a purity class of at least 5.0, is used.

[0035] Overall, the invention demonstrates how in-situ hardening of a brake disc coating can be carried out.

[0036] 4-2153

[0037] 10

[0038] Reference symbol list

[0039] 10 Brake disc 12 Base body

[0040] 14 Intermediate shift

[0041] 16 friction layer

[0042] 18 nozzle

[0043] 20 Laser beam 22 Powder beam

[0044] 24 surface

Claims

24-2153 11 Patent claims 1. Brake disc (10), comprising a base body (12) which is coated with at least one intermediate layer (14) and a friction layer (16) covering the intermediate layer (14) to the outside, wherein at least one of the layers (14, 16) has been applied to the base body (12) by means of laser cladding with nitrogen as a shielding gas.

2. Brake disc (10) according to claim 1, characterized in that the intermediate layer (14) has been applied to the base body (12) by means of laser cladding with nitrogen as a shielding gas, whereby the intermediate layer (14) has nitrides at least in the near area of ​​an outer surface facing the friction layer (16).

3. Brake disc (10) according to claim 1 or 2, characterized in that at least one of the layers (14, 16) comprises titanium nitride and / or chromium nitride and / or iron nitride, in particular tetrairon nitride, and / or aluminium nitride.

4. Brake disc (10) according to one of the preceding claims, characterized in that the friction layer (16) additionally comprises at least one hard material, in particular a carbide or a corundum.

5. Brake disc (10) according to one of the preceding claims, characterized in that the base body (12) comprises a gray cast iron alloy and / or steel and / or stainless steel and / or aluminium.

6. Motor vehicle with a brake disc (10) according to one of the preceding claims. 24-2153 12 7. Method for manufacturing a brake disc (10) wherein a base body (12) is coated with at least one intermediate layer (14) and a friction layer (16) covering the intermediate layer (14) to the outside, wherein at least one of the layers (14, 16) is applied to the base body (12) by means of laser cladding with nitrogen as a shielding gas.

8. Method according to claim 7, characterized in that the intermediate layer (14) is applied to the base body (12) by means of laser cladding with nitrogen as a shielding gas, whereby the intermediate layer (14) has nitrides at least in the near area of ​​an outer surface facing the friction layer (16).

9. Method according to claim 8, characterized in that the friction layer (16) is applied to the intermediate layer (14) by means of cold gas spraying.

10. Method according to claim 7 or 8, characterized in that the friction layer (16) is applied to the intermediate layer (14) by means of laser cladding with nitrogen as a shielding gas.

Images