WO2019219402A1

WO2019219402A1 - Braking body and method for producing a braking body

Info

Publication number: WO2019219402A1
Application number: PCT/EP2019/061332
Authority: WO
Inventors: Rainer Langlet
Original assignee: Langlet GmbH
Priority date: 2018-05-15
Filing date: 2019-05-03
Publication date: 2019-11-21
Also published as: DE202018102703U1

Abstract

The present invention relates to a braking body (10) for a brake, comprising a main body (12) with a friction surface (14) formed by roughening a surface and a coating (16) applied to the friction surface (14) by a thermal injection process after roughening is completed. According to the invention, the braking body exhibits improved adhesion between the coating and the base material of the main body. The invention further relates to a method for producing a braking body (10).

Description

Brake body and method for producing a brake body

The invention relates to a brake body for a brake, and in particular a brake body with a coated base body. The invention further relates to a method for setting forth a brake body with a coated Grundkör by.

Brake body for brakes of, for example, vehicles, for example, brake discs or brake discs, are often fig made of gray cast iron as a base material. Gray cast iron is characterized by a high volumetric heat capacity and good thermal shock resistance at a low price. These advantages are contrasted by disadvantages, which include the high weight, the strong corrosion tendency, as well as the high wear of the material in operation. The corrosion causes optical defects, as the brake disc is often visible. In addition, the tendency to corrosion of gray cast iron leads just in economical driving and / or in the case of electric and hybrid vehicles with large Rekuperationsanteilen and thus verbun which rare braking surfaces to surface damage of the friction surfaces that make necessary a premature replacement Kings NEN. Finally, the friction wear of a brake disc contributes significantly to the particulate matter emission of a vehicle.

Ceramic ceramic discs have a long service life, but are less interesting for the mass of production vehicles because of their high price.

As corrosion protection also temporary paint or powder coatings are used, but in particular on a friction surface of the brake body already at the first Bremsvor- be abraded and thus do not represent a permanent corrosion protection.

There are a variety of methods known to provide friction surfaces of brake bodies, in particular brake discs with a wear and corrosion resistant coating. As materials for coatings hard metal alloys or composites (composite materials) made of ceramic or hard metal particles are used in a metallic matrix, which offer improved behavior against corrosion and wear. As application method, in particular thermal spray injection methods are used, for example, flame or arc spraying, high-speed flame spraying (HVOF), plasma spraying, cold gas spraying, wire plasma spraying,

Wire high-speed spraying and electric wire spraying.

As an alternative to the thermal spraying process elec trolytic or galvanic methods are described, but only a poor adhesion and low ductility of the coating Be and allow low layer thicknesses. Furthermore, build-up welding methods are known, comprehensive laser beam, plasma or arc metal deposition welding, however, especially in cast iron lead to unfavorable material changes, such as the formation of brittle phases and cracks and the increase in porosity.

Furthermore, it is known to increase the adhesion of the applied layer to the base material in that the friction surface is roughened before the application of the layer. This is done, for example, by blasting using a hard material granules, by ultrasonic or laser beam treatment, by electron beam treatment or by diffusion treatment of the sub stratoberfläche by Plasmaborieren, Plasmacarburieren or by plasma nitriding. Likewise, a distance of be achieved from the surface surface by chemical, thermochemical and / or electrochemical cleaning method or by reactive tives plasma etching.

To increase the adhesion of thermal spray coatings is often a primer layer is used, which is applied between Ba sismaterial and the wear and corrosion coating and mostly consists of metals or Metalllegierun conditions. The application of such an intermediate layer, however, represents a rather complicated additional process step.

The adhesion of a thermally sprayed layer on the base material or a primer layer is based on the Prin zip the mechanical clamping of the impinging spray particles on the substrate. A much stronger connection is possible by metallurgical bonding, wherein by using thermal energy, an atomic diffusion process takes place at the interface between substrate and coating.

For this purpose, there are two alternatives to choose from: On the one hand, the substrate can be preheated before the injection process, so that the diffusion process can take place directly upon impact of Spritzparti angle. In this context, Vorwärmtempera are temperatures in the range of 120 ° C to 150 ° C known. On the other hand, there is the possibility of a melting process, in which the heating takes place after the injection process. To this end, energy-consuming process step is effected in a most experienced _V ei ne heating up to the limit of the melting temperature of the coating to accommodated.

Based on this, a brake body according to the invention with the features of claim 1 and a method for the manufacture ment of a brake body according to claim 15 is proposed. Advantageous embodiments are the subject of the claims at under.

The brake body according to the invention comprises a base body and a coating. The base body may consist of a base material such as cast iron, in particular cast iron, or another iron or steel alloy. The main body has at least one friction surface. Under a friction surface is to understand egg ne surface of the body, which is exposed in the use of the brake body strong friction.

The coating is applied to the surface formed as a friction surface of the brake body. The coating may be a wear and / or corrosion resistant coating.

The brake body thus produced has an improved adhesion between the coating and the base material of the Grundkör pers.

The brake body according to the invention can be used for all brakes that are subject to corrosion and / or high wear during operation. In addition to brakes in vehicles, these include, for example, brakes in crane systems, wind turbines or elevators.

The manufacture of the brake bodies comprises the following steps:

Providing a basic body of a base material,

Roughening a surface of the base body to form a so-called friction surface, thereby producing a certain roughness,

- Optional heating of the friction surface to a temperature of at least about 200 ° C, and - Applying a coating on the friction surface by means of a thermal spraying process.

The coating is applied to the base body by thermal spraying, preferably high-velocity flame spraying (HVOF). In high velocity flame spraying, a high velocity gas jet is produced by continuous combustion of a fuel with oxygen or air under high pressure to which the material is supplied. In most cases, a powdery material, or a material in the form of wires or rods, fed. The material particles are accelerated to a high speed and divorced from the surface to be coated Reibflä with a high density of the produced layer and high adhesion hab. The brake body according to the invention thus has a high resistance and consequently a long service life.

Depending on the requirements placed on the coating, mechanical post-treatment may be required.

The thermal spraying for applying the coating according to the invention is characterized in particular by the fact that, contrary to the standard, no pure fuel (for example kerosene, propane, propylene, etc.) is used, but hydrogen can be used as fuel additive. This gives a more ecological method than the prior art and produces less to no emissions when coating (e.g., nitrogen oxides NO x, carbon dioxide CO 2).

By using hydrogen with a significantly higher calorific value than other fuels and fuels used as standard, the substrate surface or the friction surface is more heated during thermal coating. This will sion process at the interface between the base material of the base body and the coating material, which improves the adhesion to the prior art.

Another advantage of the brake body according to the invention be is that by the described acceleration of the particles to a corresponding speed (increase in kinetic energy) a Reibverschweißung between Grundkör by and coating can be achieved. Upon impact of the particles on the base body, it may lead to an at least partially to complete friction welding of the particles with the base material. As a result, a significantly higher adhesion of the coating is achieved on the body.

The advantage of this type of friction-welded connection is that the so-called heat-affected zone is substantially smaller than in conventional welding methods and that there is no formation of melt in the "joining zone". The composite of coating and substrate, which in this embodiment is referred to as friction welding, can be determined by means of a mechanical load test. After removing a fragment from the coating, it can be seen that some of the substrate residues are still adhering or adhering to the coating itself, on the side toward the substrate. This means that the adhesion or bonding of the substrate to the coating is higher than the binding of the substrate in itself. In this context, one speaks of a partially to complete Reibverschweißung of coating and substrate.

Due to the friction-welded coating according to the invention a reduced susceptibility to cracking of the body, for example in gray cast iron or similar materials, it is sufficient. The base material gets during braking partially extreme kinetic and thermal loads from which at The body, eg cast brake disc with lamellar structure or the like, depending on the load leads to more or less cracking. By using a friction-welded Karbidbe coating, for example, a tungsten carbide coating, the base body is reinforced by the coating and thereby reduces depending on the thickness of the coating, the Rissanfäl ligkeit on the reduction of the force introduction of kinetic and thermal energy.

A speed of the particles, which leads to a partial to complete friction welding between the base body and coating, also leads to much denser and thus with wear-resistant layers compared to the prior art. Occasionally, these required Partikelge speeds can be achieved by the use or addition of hydrogen as / to the fuel.

In the much denser Reibverschweißten coating, the microcapillarity is so fine that the penetration of moisture is reduced so much that only a clotting ger water film can build up, which is not noticeable when braking bar or a sliding effect in the wet is not noticeable.

By this type of coating even Lo tosblüteneffekt on the coated surface is recognizable or possible. As a result, an improved or faster braking effect despite extreme wet conditions on the brake discs available.

To further increase the adhesion, the friction surface can be heated immediately before coating by means of the flame of the spraying method used (without using the coating material). A temperature of at least 200 ° C made light diffusion processes in the interface between the base material of the body and to a sufficient extent the coating material for a material connection. When using hydrogen, which is as described above be characterized by its compared to other fuels higher calorific value, a faster and thus eco nomic heating of the friction surface while Re reduction of the atmosphere and thereby oxide-free friction surfaces is possible, resulting in a better connection of the Beschichtungsma terials on the base material leads. In addition, no further process or other technology is required for heating the friction surfaces (eg inductive heating, by means of an oven, etc.). The ecological aspect must also be taken into account.

It is also possible to heat the friction surface with the described enclosed method to temperatures well above 200 ° C and thus to increase the expression of the diffusion processes and thus the adhesion of the coating to the base material. The temperatures are to be limited so that no unfavorable conditions structural changes of the base material take place.

The high-energy flame spraying, in particular high-speed flame spraying, leads to the production of coatings with particularly high adhesive strength and density. Alternatively, but less preferably, the coating may be applied by means of another thermal spraying method, for example arc spraying, plasma spraying, cold gas spraying or detonation spraying.

The layer thicknesses can be in the range of about 50 ym to 500 ym. More preferably, however, a range of 100 ym to 300 ym is generated. Depending on the spraying method and the layer thickness of the layer structure can be made up to a gewünsch th layer thickness of the coating further preferably by repeated deposition of several individual layers. As a material for the coating are in principle all materials in question, compared to the base material, which is in particular gray cast iron, a higher corrosion or wear resistance Ver, preferably both a higher corrosion ons- and a higher wear resistance have. According to a preferred embodiment of the brake body, the coating encloses a material made of a non-oxidic ceramic material and / or a metal or a metal alloy. More preferably, a carbide, a boride, a nitride or mixtures of these used as a non-oxidic Keramikma material. Carbides, in particular carbidic hard mate rials, have higher adhesive strengths. In addition, the thermal conductivity of the carbides has a positive effect compared to oxides. As metal or metal alloys are preferential, iron, nickel, chromium and their alloys in question. Ni ckel and nickel-chromium alloys have proved to be advantageous in terms of the achieved layer and connection quality. The material can be set as a powder or powder mixture. In further preferred embodiments, tungsten carbide / cobalt, tungsten carbide / cobalt / chromium or chromium carbide or chromium carbide / nickel / chromium are used.

In an advantageous embodiment of the invention, the coating has a graduation. With the described method, a graduated application of the coating with the various aforementioned materials is possible. This means that one can move from a certain material, possibly also a material mixture, over certain mixing ratios to another desired material, possibly also to another mixture of materials. This may be neces sary for certain requirements and environmental conditions to the brake or its friction surface in view of the circumstances. For example, if a friction surface is subject to very high hen temperature fluctuations or is interpreted for very high temperatures, can mix of a material, or a Werkstoffge, with, for example, higher linear Ausstehnungskoeffizi ducks to a material, or a mixture of materials, for example, lower linear expansion coefficient, but for example with a higher wear resistance passed or graduated. Basically, with these graduations, the best possible transition from the starting base, the substrate, to the desired properties taking into account the conditions or requirements and environmental influences is made possible.

According to a further advantageous embodiment, the coating of, for example, tungsten carbide has an additional oxide or ceramic coating, preferably of chromium oxide. Ceramics can no longer oxidize and have a higher hardness than tungsten carbide. The carbide layer, for example, tungsten carbide layer, acts as an adhesive layer for the ceramic coating in this embodiment. The carbide coating, in particular the tungsten carbide coating, which is additionally coated with ceramics, e.g. Chromium oxide, coated or implanted, has an even higher hardness and thus clotting Geren wear.

Another advantageous aspect of the invention is that contrary to known brake bodies no additional adhesion mediator layers (adhesive layers) and / or Korrosionsschich th are required, which applied in the prior art in an additional step and / or process who need to.

The preparation of the friction surface to be coated can be carried out with the usual method in thermal spraying, the blasting of the surface to be coated, and there are no spe- essential measures such as the creation of a special len surface profile required.

In order to reduce the high surface roughness obtained during thermal spraying, a final mechanical post-processing of the coating produced can preferably take place after the thermal spraying. This is done before preferably with a tool with geometrically indeterminate edge, for example by grinding. The upper surface roughness can be reworked to a depth that meets the requirements. The described method with a correspondingly fine coating material, it is possible to achieve a very fine surface roughness, where with depending on the requirements of the surface roughness of the friction surfaces a possible mechanical post-processing can be superfluous.

By partially to completely Reibverschweißung, the coating of the brake body according to the invention has a particularly high adhesive strength. In addition, the coating has a very high density with a higher binding enthalpy, which leads to a very good resistance to wear and / or corrosion. Time- and cost-intensive pre-treatment and adhesion promoter layers are superfluous. In addition, the partial to full use of hydrogen as fuel is a world-conscious and ecological process in which, compared to the state of the art, less or no emissions (NoX, Co2, etc.) are produced.

In the case of the brake body according to the invention, in particular for a vehicle which is manufactured or can be produced by the described method, it may preferably be a brake act for a disc brake or a brake drum for a drum brake.

The invention also relates to a method for producing a brake body with the steps:

Providing a basic body of a base material,

- roughening a surface of the base body to form a friction surface, to produce a predetermined roughness, and

- Applying a coating on the friction surface by means of a thermal spraying process.

With the method according to the invention, the brake body according to the invention can be produced for a brake. The braking device thus provided has improved adhesion between the coating and the base material of the base body.

The inventive method can be trained with further described in connexion with the braking body according to the invention paint.

The invention will be described below by way of example with reference to the attached drawing beige on the basis of an advantageous embodiment. Show it:

Fig. 1: a schematic view of the various steps te a) to e) for the production of the brake body according to the invention, wherein

1a is a schematic sectional view and enlarged view of the uncoated base body, 1 b shows a schematic sectional view and enlarged view of the base body after roughening or straightening,

1c shows a schematic sectional view of the main body after the possible heating,

Fig. Id: a schematic sectional view and an enlarged view of the main body after applying the coating Be,

Fig. Le: a schematic sectional view and enlarged view of the body after the aftertreatment is.

In Fig. La) is an edge section of a base body to be coated 12 of a brake body 10 is shown, which is a brake disc for a disc brake of a motor vehicle in the water embodiment. The base body 12 has on its outer circumference the friction surface 14 to be coated. The main body 12 is made in this embodiment of gray iron by means of a conventional casting process.

In a first step, a roughening of the Grundkör pers 12 in the region of the friction surface 14. This is preferably done using a blasting machine, in which the base body 12 is inserted into a receptacle and not covered to cover the areas and thus protected from the blasting , Thereafter, the base body 12 is rotated and roughened with a defined jet material and pressure by means of the blasting process.

As shown in FIG. 1b), the result of this beam processing is a "mountain profile" or "mountain and valley profile" of the friction surface 14. This can best be explained by the enlargement in FIG Fig. Lb) remove. The roughness depth Rz is in this case determined by the blasting process, the blasting material or material, the pressure and the feed. The desired roughness is defined as a function of the desired layer thickness. Vorlie ing jet particles can be removed by blowing off.

In Fig. Lc) is the possibility of heating the Grundkör pers 12 in the region of the friction surface 14 by means of the spray burner (without the addition of spray materials) shown. In order to assist the diffusion processes in the subsequent spraying should be heated to at least 200 ° C to about 1000 ° C. It should be noted that with increasing temperature, the diffusion processes are favored. This step is a way to improve liability even further. Basically, however, it should be noted that the adhesion in the described method is already well above the standard and this step is not required son only optional depending on the application or requirement profile of the brake body can be provided.

In the step shown in FIG. Id), the coating 16 is applied to the base body 12 by means of a thermal spraying process, in this embodiment the high-speed flame spraying. For this purpose, for example, a material consisting of tungsten carbide / cobalt is used. The application of the coating 16 takes place in several steps or layers until a desired layer thickness, for example, in the range of 50 ym to 400 ym is obtained.

Following the application of the coating 16 ei ne final mechanical post-processing of the previously applied coating 16. This is in most cases he required because the applied by means of thermal spraying Coating 16 usually have higher surface roughness than that of the requirements. Mainly this mechanical post-processing is done with a geometrically indeterminate cutting edge. Depending on the requirements, a corresponding surface roughness of the coating can be achieved hereby.

The combination of the roughening and the thermal spraying produces a brake body 10 with a dense coating 16, which has high adhesion to the base body 12. It is seen from ecological Ge point of view with cost-effective means feasible bar. Thus, the costs are much lower than previous methods, which e.g. Consider an additional heating step with another method and / or a chemically or electrochemically applied intermediate layer as a primer layer and thereby also emissions Verur things

Claims

claims

1. brake body (10) for a brake, in particular for a

Having vehicle, with a base body (12) having a trained by rough surface as a friction surface (14) and after a roughening by means of a thermal spray process on the friction surface (14) applied Beschich device (16).

Second brake body (10) according to claim 1, whose base body (12) made of cast iron, preferably gray cast iron, is produced.

3. brake body (10) according to claim 1 or 2, wherein it is in the thermal spraying method to flame spraying, preferably, as high-speed flame spraying is.

4. brake body (10) according to claim 3, wherein hydrogen is used as fuel or fuel additive.

5. brake body (10) according to any one of the preceding claims, the coating (16) has a high density and / or high adhesion.

6. brake body (10) according to any one of the preceding claims, the coating (16) with the main body (12) teilwei se or completely friction welded.

7. brake body (10) according to any one of claims 5 or 6, the coating (16) has a fine microcapillarity, so that the penetration of moisture is reduced.

Brake body (10) according to any one of the preceding claims, whose coating (16) has a layer thickness of 50 ym to 500 ym, preferably from 100 ym to 300 ym and / or formed by repeated deposition of multiple individual layers and / or has a graduation.

9. brake body (10) according to any one of the preceding claims, the coating (16) compared to the base body (12) has a higher corrosion and / or wear resistance.

10. brake body (10) according to any one of the preceding claims, the coating (16) a non-oxidic Keramikmate material, preferably a carbide hard material, more preferably tungsten carbide or chromium carbide, and / or a metal or a metal alloy, preferably a nickel or nickel Chromium alloy, includes.

11. brake body (10) according to claim 10, the Beschich

tion (16) of a carbide hard material an additional Liche oxide or ceramic coating, preferably of chromium oxide having.

12. brake body (10) according to any one of the preceding claims, the coating (16) on one of the friction surface (14) from side facing a low surface roughness has.

13. brake body (10) according to any one of the preceding claims, wherein it is the brake body (10) is a brake disc be for a disc brake or a brake drum for a drum brake.

14. Brake body (10) according to any one of the preceding claims, wherein the base body (12) in the region of the friction surface (11) and immediately before the application of the coating (12). has an elevated temperature, preferably at least 200 ° C.

15. A method for producing a brake body (10), comprising the steps of:

- Providing a base body (20) made of a base material,

Roughening a surface of the base body (12)

Forming a friction surface (14), generating a predetermined roughness, and

- Applying a coating (16) on the Reibflä

che (14) by means of a thermal spraying process.