BRAKE DISC AND METHOD FOR PRODUCING IT

Abstract

The invention relates to a brake disc (3), which has at least one thermal conduction layer (4, 6) with a specific thermal conductivity and thermal resistivity that can be graduated, the thermal conduction layer consisting of at least two different materials or of a variable layer thickness, thereby graduating the thermal conductivity or the thermal resistivity within the thermal conduction layer.

Claims

1. A brake disc comprising a metallic main body (1) having at least one ring-shaped locking element (12) for securing the brake disc to a rotating axis (14), a first friction region (2) oriented to a rotating axis (14) and in the form of a circular surface, and a second friction region (3) arranged diametrically opposite the first friction region (2) and away from a rotating axis, characterized in that the metallic main body (1), in the first and second friction regions (2, 3), has at least one ring-shaped heat-conducting layer (4, 6) on top of which at least one layer of tribologically stressable hard material (8) is disposed, wherein at least one heat-conducting layer (4, 6) is disposed on top of the metallic main body (1) and the layer of tribologically stressable hard material (8) is on top of the heat-conducting layer (4, 6).6) by means of laser accumulation welding, to achieve a cohesive bond between the layers, wherein the heat conduction layer (4, 6) consists of at least two different materials and the thermal conductivity λ within the heat conduction layer (4, 6) is graded, wherein there is a metal or ceramic and / or metal alloy material having a thermal conductivity λι at least in an inner circumferential region (9) of the first and / or second friction regions (2, 3), and wherein there is a metal or ceramic and / or metal alloy material having a thermal conductivity λ2 in an outer circumferential region (11) of the first and / or second friction regions (2, 3), wherein at least λι < λ < λ2.

2. A brake disc comprising a metallic main body (1) having at least one ring-shaped locking element (12) for securing the brake disc to a rotating axis (14), a first friction region (2) oriented to a rotating axis and taking the form of a circular surface, and a second friction region (3) arranged diametrically opposite the first friction region (2) and away from a rotating axis (14), wherein the metallic main body (1), in the region of the first and / or second friction regions (2, 3), has at least one ring-shaped heat-conducting layer (4, 6) above which at least one layer of tribologically stressable hard material (8) is disposed, wherein at least one heat-conducting layer (4, 6) is disposed above the metallic main body (1) and the layer of tribologically stressable hard material (8) above the heat-conducting layer (4, 6).6) by means of laser accumulation welding, to achieve a cohesive bond between the layers, and wherein at least one of the heat conduction layers (4, 6), in the radial direction with respect to the outer circumference of the brake disc, has a graduated layer thickness dsw, ML / t / ZUZZ / UOU^OO as a result of which the specific thermal resistance Rth¡ decreases in the heat conduction layer (4, 6) in the radial direction towards the outer circumference of the brake disc.

3. The brake disc according to claim 1 or 2, further characterized in that there is an arrangement of at least two heat conduction layers, wherein a first heat conduction layer is arranged on top of the main metallic body and a second heat conduction layer is arranged on top of the first heat conduction layer, wherein the at least second heat conduction layer in each case forms an interfacial region with the tribologically stressable hard material layer and with the first heat conduction layer.

4. The brake disc according to at least one of the preceding claims, further characterized in that at least one heat conduction layer and / or the tribologically stressable hard material layer in the friction region oriented towards a rotation axis is formed with a different layer thickness compared to the at least one heat conduction layer and / or stressable hard material layer in the friction region away from a rotation axis.

5. The brake disc according to at least one of the preceding claims, further characterized in that, in the radial direction towards the outer circumference of the brake disc, there is at least one heat conduction layer in an inner circumferential region extending up to a maximum of 40% of the circumferential area, a material having a thermal conductivity λι of 10 W / (nrK) to 14 W / (m K), in a middle circumferential region extending from 30% to a maximum of 65% of the circumferential area, a material having a thermal conductivity λ2 of 12 W / (nrK) to 26 W / (nrK), and in an outer circumferential region extending from 60% to the outer circumference of the circumferential area, a material having a thermal conductivity As of 24 W / (mK) to 40 W / (m'K).

6. The brake disc in accordance with at least one of the preceding claims, further characterized in that at least one heat conduction layer has a layer thickness dsw that increases continuously or abruptly in the radial direction towards the outer circumference of the brake disc.

7. The brake disc in accordance with at least one of the preceding claims, further characterized in that at least one heat conduction layer has a layer thickness dsw¡ of 50 pm to 500 pm, particularly advantageously a layer thickness dsw¡ of 100 pm to 150 pm.

8. The brake disc according to at least one of the preceding claims, further characterized in that in the radial direction towards the outer circumference of the brake disc, the heat conduction layer has a 10%-15% greater layer thickness dswi in an inner circumferential region extending to a maximum of 40% of the circumferential area and, in a middle circumferential region extending from 30% to a maximum of 65% of the circumferential area, a layer thickness dsw2 between 5% and 10% greater compared to the layer thickness dsws in an outer circumferential region extending from 60% of the circumferential area to the outer circumference, wherein the composition of the layer consisting of the heat conduction layer and the tribologically stressable hard material layer is constant.

9. The brake disc in accordance with at least one of the preceding claims, further characterized in that the heat conduction layer has been produced from an alloy based on Al, Fe, Ni, Cr and / or Cu.

10. The brake disc in accordance with at least one of the preceding claims, further characterized in that at least one heat conduction layer also includes particles of hard ceramic carbide and / or oxide material.

11. The brake disc according to claim 10, further characterized in that the hard material particles of the heat conduction layer have an average particle size Dso of 0.5 pm to 120 pm. 12.- The brake disc according to claim 10 or 11, further characterized in that the volume proportion of hard material particles in the heat conduction layer is from 1% to 80%, particularly advantageously from 30% to 50%.

13. The brake disc according to at least one of the preceding claims, further characterized in that the heat conduction layer takes the form of an alloy wherein, in an axial direction, the lowest thermal conductivity is in a partial radial region and in the interfacial region with the tribologically stressable hard substance layer, and the highest thermal conductivity is in the interfacial region with an additional heat conduction layer or the main metallic body. 14 - The brake disc in accordance with at least one of the preceding claims, further characterized in that there is at least one bonding layer between the main metallic body and at least the first heat conduction layer.

15. The brake disc in accordance with at least one of the preceding claims, further characterized in that the tribologically stressable hard material layer has at least a dsH layer thickness of 50 pm to 500 pm, particularly advantageously a dsH layer thickness of 200 pm to 250 pm.

16. The brake disc according to at least one of the preceding claims, further characterized in that the tribologically stressable hard material layer consists of a cermet, particularly advantageously of silicon carbide, boron carbide, tungsten carbide, vanadium carbide, titanium carbide, tantalum carbide, chromium carbide and / or an oxide ceramic, and most particularly advantageously of tungsten carbide with a stainless steel matrix of material group 4 or 5 having a Ni content of < 15% by mass.

17. A method for producing the brake disc according to at least one of claims 1 to 16, characterized in that a first heat-conducting layer (4, 6) is placed in a cohesive manner, at least partially, on top of a metallic main body (1) by means of laser build-up welding, and a tribologically stressable hard material layer (8) is then cohesively deposited on top of the first heat-conducting layer (4, 6), wherein the heat-conducting layer (4, 6) is made of at least two different materials and the thermal conductivity λ within the heat-conducting layer is graded, such that the heat-conducting layer has a thermal conductivity λ that increases in the radial direction.wherein a metallic or ceramic material and / or a metallic alloy having a thermal conductivity λι is disposed in at least an inner circumferential region (9) of the first and / or second friction regions (2, 3) and a metallic or ceramic material and / or a metallic alloy having a thermal conductivity λ2 is disposed in an outer circumferential region (11) of the first and / or second friction regions (2, 3), and the surface of the tribologically stressable hard material layer (8) is finally processed.

18. A method for producing the brake disc according to at least one of claims 1 to 16, characterized in that a first heat-conducting layer (4, 6) is arranged in a cohesively bonded manner, at least partially, on a metallic main body (1) by means of laser build-up welding, and a tribologically stressable hard material layer (8) is then arranged in a cohesively bonded manner on top of the first heat-conducting layer (4, 6) to achieve a cohesive bond between the layers (4, 6, 8), wherein at least one heat-conducting layer (4, 6), radially with respect to the outer circumference of the brake disc, is arranged with a graduated layer thickness dsw, as a result of which the specific thermal resistance Rtn¡ decreases in the heat-conducting layer (4, 6) radially towards the outer circumference of the brake disc.

19. The method according to claim 18, further characterized in that, in a first step, in the radial direction, the heat conduction layer is arranged in an inner circumferential region extending up to a maximum of 35% of the circumferential area with a layer thickness 10%-15% greater than ds1, and in an inner circumferential region extending from 30% to a maximum of 65% of the circumferential area with a layer thickness ds2 between 5% and 10% greater compared to the layer thickness ds3 in an outer circumferential region extending from 60% of the circumferential area to the outer circumference of the brake disc, such that the specific thermal resistance Rth1 gradually decreases in the heat conduction layer from the inner circumferential region to the outer circumferential region.

20. The method according to at least one of claims 17 to 19, ML / t / ZUZZ / UOU^OO, further characterized in that, in the radial direction towards the outer circumference of the brake disc, at least one heat conduction layer is disposed in an inner circumferential region extending up to a maximum of 35% of the circumferential area, a material having a thermal conductivity λι of 10 W / (mK) to 14 W / (mK), in a middle circumferential region extending from 30% to a maximum of 65% of the circumferential area, a material having a thermal conductivity λ2 of 12 W / (nrK) to 26 W / (nrK), and in an outer circumferential region extending from 60% to the outer circumference of the circumferential area, a material having a thermal conductivity As of 24 W / (nrK) to 40 W / (m'K).

21. The method in accordance with at least one of the preceding claims 10, 17 to 20, further characterized in that, before the heat conduction layer is placed by means of a laser build-up weld, the main metallic body is heated in at least a subregion of the first and / or second friction regions to a temperature of 150°C to 500°C.