Disc-brake disc for a vehicle or a wind turbine, a method for producing a disc-brake disc, and a method for producing a cast aluminium alloy for a disc-brake disc

Abstract

The invention relates to a disc-brake disc 20 for a vehicle or for a wind turbine having a friction ring 21, the disc-brake disc 20 being made of a cast aluminium alloy, and the cast aluminium alloy comprising: 7.0 to 10.0 wt.% silicon; 0.25 to 5.0 wt.% titanium; 12.0 to 30.0 wt.% silicon carbide particle reinforcement and the remaining amount being aluminium, and the silicon carbide particle reinforcement having an average particle size of at least less than 30 micrometres. The invention also relates to a method for producing a disc-brake disc and to a method for producing an aluminium alloy for a disc-brake disc.

Description

[0001] P400167WO_20251027 Page 1 | 25

[0002] Disc brake disc for a vehicle or wind turbine, a method for manufacturing a disc brake disc, and a method for manufacturing an aluminium casting alloy for a disc brake disc

[0003] The present invention relates to a disc brake disc for a vehicle or for a wind turbine according to claim 1 and a method for manufacturing a disc brake disc according to claim 10, as well as a method for manufacturing an aluminium casting alloy for a disc brake disc according to claim 18.

[0004] Technological background

[0005] To meet the increasing demands for fuel efficiency in automotive engineering, it is known that reducing the overall weight of a car improves its fuel consumption. For example, similar to a typical steel brake disc, a 10% reduction in vehicle weight can lead to an improvement in fuel consumption of approximately 6-8%. Therefore, it is desirable to use lighter materials for the frame, body panels, and components of a vehicle.

[0006] Such materials include high-strength steel, magnesium alloys, aluminum alloys, carbon fibers, and polymer composites.

[0007] At the same time, it is important that when choosing lightweight materials as replacements for conventional, heavier materials, a high degree of strength, performance and durability of the parts manufactured from them is maintained.

[0008] In the case of a vehicle disc brake, a disc brake disc should be made of lightweight material, have high thermal conductivity and diffusion capacity, as well as good strength and high creep resistance (e.g., resistance to deformation over time) at elevated temperatures. P400167WO_20251027 Page 2 | 25

[0009] With the upcoming introduction of the Euro 7 standard in Europe from 2027 onwards, it is necessary to develop innovative brake discs to comply with the new regulations and meet the increased demands for environmental friendliness and performance. The Euro 7 standard will, for the first time, establish strict limits for particulate emissions from brake and tire wear in order to improve air quality and minimize health risks from fine dust. For purely electric vehicles, the limit will be 3 mg / km, and for all other drive types, it will be 7 mg / km PM10 emissions. Therefore, it is essential to develop a brake disc that meets the Euro 7 standard.

[0010] Prior art patent CN106812837A discloses a composite brake disc made of aluminum, comprising a disc body. The disc body includes a composite structure consisting of a disc core and a friction layer covering the disc core. The disc core is made of an aluminum alloy, and the friction layer is made of a particle-reinforced aluminum-based composite material. The frictionless surface (disc core) of the brake disc is cast using an aluminum alloy with good ductility and toughness. The friction surface (friction layer) is cast onto the disc core using a particle-reinforced aluminum-based composite material. Finally, the brake disc is formed, with its inner surface consisting of the aluminum alloy and its outer surface of the particle-reinforced aluminum-based composite material.The brake disc offers the advantages of low density, high specific strength and stiffness, a low coefficient of thermal expansion, good thermal conductivity, excellent wear resistance, etc. Furthermore, the toughness of the brake disc is improved during assembly, machining costs are reduced, and the operational reliability of the brake disc is enhanced.

[0011] The prior art includes JPH116024A, an aluminum alloy composite with excellent water resistance suitable for use as a brake disc for two-wheeled vehicles, four-wheeled vehicles, and rail vehicles. This material is a composite formed by the distribution of hard grains of one or more types, selected from SiC, Al₂O₃, Al₂O₃, Si₃N₄, and SiO₂, in a rapidly solidifying aluminum alloy matrix. P400167WO_20251027 Page 3 | 25

[0012] Regarding the hard grain content in the composite material, the content of hard grains with an average grain size of 1-5 pm is 7-20%, and the content of hard grains with an average grain size of 7-25 pm is 0.5-5%, resulting in a total hard grain content of 7.5-22%. For the aluminum alloy forming the matrix, a composition containing 5-15% Si and 0.5-3% Cu, or an aluminum alloy produced by adding 0.05-0.5% Mg to the above composition, is preferred. This composite material is particularly suitable for brake discs subjected to high loads. Using this composite material allows for stable braking characteristics while minimizing wear during braking and preventing seizing.

[0013] Prior art patent JPH09184037A discloses the production of an aluminum alloy composite for brake discs capable of preventing surface overheating due to frictional heat. This composite consists of a compacted aluminum alloy powder with a composition of 2-10% Si, a total of ≤ 2% of one or ≥ 2 elements from Ni, Cu, Fe, Zn, Mn, Ti, and Cr, and the remainder being Al with unavoidable impurities. Furthermore, SiC grains and / or AlN grains with an average grain size of 1-15 pm are distributed in the matrix of the compact to a total of 3-15%, and the thermal conductivity is adjusted to ≥ 180 W / Mk.

[0014] A disadvantage of the aforementioned state of the art is that excessively small silicon carbide particles lead to clumping, resulting in inhomogeneity or pores in the disc brake disc. These pores cause high tool wear during manufacturing and impair heat conduction. Furthermore, an insufficient silicon content in the aluminum casting alloy weakens its heat resistance. This reduces the wear resistance of the aluminum casting alloy and increases thermal expansion, thus raising the risk of thermal cycle cracking.

[0015] The prior art is known in WO2024 / 182060 A1. It provides a disc brake disc for a vehicle. The disc brake rotor comprises a cap and a friction ring extending circumferentially from the cap. The brake disc is made of a cast hypereutectic aluminum alloy. The hypereutectic aluminum alloy contains: 14.00 to 25.00 P400167WO_20251027 Page 4 | 25

[0016] wt% silicon; 4.90 to 8.00 wt% copper; 0.05 to 0.90 wt% nickel; 0.50 to 1.50 wt% magnesium; 0.05 to 1.20 wt% iron; 0.05 to 1.00 wt% manganese; 0.05 to 1.00 wt% zinc; 0.05 to 1.20 wt% titanium; 0.05 to 1.20 wt% zirconium; 0.05 to 1.20 wt% vanadium; 0.001 to 0.10 wt% phosphorus; and the remainder aluminum. The alloy may also contain other trace elements such as chromium, lead, and tin in amounts not exceeding 0.20 wt%. The brake disc rotors may be manufactured by a high-pressure semi-solid die-casting process, including rheocasting.

[0017] A disadvantage of this known solution is that such disc brake discs do not thermally meet the requirements of modern braking systems and are only produced to reduce the overall weight of a vehicle in order to increase its range or reduce fuel consumption. Furthermore, the aforementioned manufacturing processes are not economical for mass production.

[0018] Description of the invention

[0019] One object of the invention is to avoid at least one of the disadvantages of the prior art. In particular, an improved disc brake disc is to be created which develops less particulate matter emissions during the braking process in a vehicle. Furthermore, an improved method for manufacturing a disc brake disc and an aluminum casting alloy for a disc brake disc is to be developed.

[0020] This problem is solved by the features of the independent patent claims. Advantageous developments are set out in the figures and in the dependent patent claims.

[0021] An inventive disc brake disc for a vehicle or for a wind turbine comprises at least one friction ring, wherein the disc brake disc is formed from an aluminum casting alloy, and wherein the aluminum casting alloy comprises at least 7.0 to 10.0 wt.% silicon; 0.25 to 5.0 wt.% titanium; 12.0 to 30.0 wt.% silicon carbide particle reinforcement and the remainder aluminum, and wherein the silicon carbide particle reinforcement has a mean particle size of at least less than 30 micrometers. In particular, the mean particle size of P400167WO_20251027 Page 5 | 25 is at least greater than 15 micrometers, so that a particularly advantageous embodiment of the disc brake disc is feasible.

[0022] Such a disc brake disc exhibits significantly reduced particulate matter emissions during braking in a vehicle. Since the inventive disc brake disc has no coatings, it is easy to manufacture and exhibits low wear. Furthermore, this disc brake disc offers improved thermal resistance, corrosion resistance, negligible brake noise, and reduced weight. This reduced weight results in a considerable improvement in the vehicle's range. A lighter vehicle requires less energy to move, which directly leads to lower energy consumption per kilometer. For electric vehicles, this translates to a longer battery range, making vehicle use more efficient. For combustion engine and hybrid vehicles, the weight reduction leads to improved fuel efficiency and reduced CO2 emissions.

[0023] The disc brake disc according to the invention is also ideally suited for use in wind turbines. In this application, the rotating parts, such as the rotor, need to be braked periodically using the disc brake disc. However, the braking system with the disc brake disc is usually not in active use. Wind turbines are generally exposed to varying weather conditions. The low susceptibility to corrosion of the disc brake disc is a significant advantage, particularly for offshore wind turbines.

[0024] The innovative disc brake disc offers a genuine alternative to conventional steel brake discs and opens up new possibilities for improved performance, efficiency, and environmental friendliness in vehicle technology. The innovative disc brake disc is characterized by its superior material properties. Through the innovative combination of the materials mentioned here, it offers a significant reduction in particulate matter emissions, while maintaining at least the same technical requirements for disc brakes as the state of the art. The innovative disc brake disc exhibits exceptional corrosion resistance, reduced thermal deformation, improved heat dissipation, and significantly higher resistance to wear compared to conventional steel brakes. Brake abrasion is a significant factor. P400167WO_20251027 Page 6 | 25

[0025] A source of particulate matter in road traffic, and by significantly reducing these emissions, the inventive disc brake disc makes an important contribution to achieving the environmental goals of the future mandatory Euro 7 standard.

[0026] In an advantageous embodiment, the silicon content is 7.5% by weight, more advantageously 8%, even more advantageously 8.5%, still more advantageously 9.0%, and still more advantageously 9.5%. This allows the production of simple aluminum casting alloys with AISi7, AISi8, AISiQ, or AISi10. Silicon imparts a high modulus of elasticity and a low coefficient of thermal expansion to the alloy. The addition of silicon is essential to improve the flowability of the molten aluminum and thus enhance the castability of the Al-Si alloy according to the present invention. At high silicon content, i.e., above 7% by weight, the alloy exhibits excellent surface hardness and wear resistance, thereby extending its service life.

[0027] In an advantageous embodiment, the weight percentage of titanium is 0.5%, more advantageously 1%, even more advantageously 1.5%, even more advantageously 2%, even more advantageously 2.5%, even more advantageously 3%, even more advantageously 3.5%, even more advantageously 4%, and even more advantageously 4.5%. The Al-Ti compounds act as nuclei for grain size refinement during the solidification of the molten aluminum casting alloy in the casting process. Titanium also acts as a dispersion reinforcing agent and exhibits a lattice structure similar to that of solid aluminum solution to improve the mechanical properties at high temperatures. The titanium in the aluminum casting alloy increases the alloy's hardness and reduces disc brake wear, thus minimizing fine dust formation. A particular advantage of this inventive disc brake disc is that, due to the increased weight,The addition of titanium increases the melting point of the alloy, thereby significantly improving the heat resistance of the disc brake disc. It has been found that the solidus temperature of the disc brake disc can be increased to up to 850°C when titanium is added to the alloy during the casting process. In comparison, without titanium, the solidus temperature for such an aluminum casting alloy is only 550°C. The titanium content significantly increases hardness and reduces wear depth and volume, thus minimizing fine dust formation. This leads to less structural loss due to increased temperature stability, improved microstructure refinement resulting in a higher yield strength, and crack inhibition, leading to a fine-grained microstructure within a stable matrix.The solidus temperature characterizes the temperature of an alloy at and below which the substance exists completely in the solid phase.

[0028] In known aluminum casting alloys that do not have the composition disclosed here, carbides form in the aluminum casting alloy matrix, leading to crack initiation and embrittlement of the material. The general challenge with solidus-temperature-increasing alloying additions (such as titanium) is that, depending on their concentration, they do not completely dissolve at 850 °C, but rather exist partially as unmelted, solid intermetallic phases. These significantly increase the viscosity in the melt, resulting in new casting conditions. Therefore, it is not typical to add titanium in increased concentrations to an aluminum alloy that can be produced using a casting process. The increased viscosity in the alloy melt alters the solidification conditions, which can be controlled by adhering to the correct sequence of additions, such as...Titanium, to be handled in such a way that the disc brake disc according to the invention can be manufactured and has a reduced fine dust emission.

[0029] In an advantageous embodiment, the wt% silicon carbide particle reinforcement is 12.5%, even more advantageous at 13%, even more advantageous at 13.5%, even more advantageous at 14%, even more advantageous at 14.5%, and even more advantageous at 15%. even more advantageous at 15.5%, even more advantageous at 16%, even more advantageous at 16.5%, even more advantageous at 17%, even more advantageous at 17.5%, even more advantageous at 18%, even more advantageous at 18.5%, even more advantageous at 19%, even more advantageous at 19.5%, even more advantageous at 20%, even more advantageous at 20.5%, even more advantageous at 21%, even more advantageous at 21.5%, even more advantageous at 22%, even more advantageous at 22.5%, even more advantageous at 23%, even more advantageous at 23.5%, even more advantageous at 24%, even more advantageous at 24.5%, even more advantageous at 25%, even more advantageous at 25.5%, even more advantageous at 26%, even more advantageous at 26.5%, even more advantageous at 27%, even more advantageous at 27.5%, even more advantageous at 28%, even more advantageous at 28.5%, even more advantageous at 29%, even more advantageous at 29.5%. The SiC particles are a ceramic that is extremely hard and resistant. When these are incorporated into an aluminum casting alloy at increased wt.%, they significantly increase the abrasion and wear resistance of the base alloy with aluminum. P400167WO_20251027 Page 8 | 25.

[0030] Furthermore, silicon carbide (SiC) increases the strength of the aluminum casting alloy, significantly enhancing both its tensile strength and yield strength. Additionally, silicon carbide exhibits high thermal conductivity and heat resistance. This allows heat to be dissipated more quickly from the aluminum alloy, thereby increasing its heat resistance. These properties are particularly advantageous for the disc brake disc described herein.

[0031] Silicon carbide particle reinforcement with an average particle size of less than 30 micrometers enables cost-effective production of the disc brake disc. Such a disc brake disc exhibits improved surface quality, enhanced braking performance, reduced wear, and increased performance stability.

[0032] The special composition of materials in this innovative disc brake disc ensures exceptional resistance to mechanical wear. This helps the disc brake disc maintain its optimal performance for a longer period. Conventional steel brakes tend to wear and deform due to repeated stress and thermal influences, compromising their efficiency and safety. This disc brake disc, however, is designed to withstand these stresses significantly better and for a longer time. Its high wear resistance means less frequent replacements and therefore lower maintenance costs over the vehicle's lifetime. Furthermore, the extended lifespan of this disc brake disc contributes to sustainability by reducing the need for resources on spare parts and maintenance.

[0033] The innovative disc brake disc offers not only improved performance and safety, but also excellent environmental compatibility and sustainability. Its superior material properties ensure good recyclability. This makes a significant contribution to environmental protection by reducing particulate matter emissions and conserving resources through a significantly longer service life, thus minimizing waste production. P400167WO_20251027 Page 9 | 25

[0034] Preferably, the aluminum casting alloy comprises at least one of the following elements: 0.5 to 5.0 wt.% copper; 0.5 to 5.0 wt.% nickel; 0.5 to 5.0 wt.% magnesium; 0.5 to 5.0 wt.% iron; 0.1 to 5.0 wt.% zinc; 0.1 to 5 wt.% boron. The combination of copper and magnesium forms a solid solution in the aluminum matrix to impart age-hardenable properties to the aluminum casting alloy and thereby improve its high-temperature strength.

[0035] The copper content influences the strength at higher temperatures and increases the thermal conductivity during the operation of the disc brake disc. Furthermore, the alloy's strength can be improved by adding the correct proportion of magnesium relative to the copper and silicon. In addition, the unique Cu-Mg ratio enhances the chemical reactions between aluminum (Al), copper (Cu), and magnesium (Mg) atoms. These chemical reactions allow for the precipitation of a higher volume fraction within the aluminum casting alloy. This results in exceptional tensile strength and microstructural stability at elevated temperatures.

[0036] In an advantageous embodiment, the wt.% copper is 0.5%, more advantageous at 1%, even more advantageous at 1.5%, even more advantageous at 2%, even more advantageous at 2.5%, even more advantageous at 3%, even more advantageous at 3.5%, even more advantageous at 4%, even more advantageous at 4.5%.

[0037] In an advantageous embodiment, the weight percent magnesium is 0.5%, more advantageously 1%, even more advantageously 1.5%, even more advantageously 2%, even more advantageously 2.5%, even more advantageously 3%, even more advantageously 3.5%, even more advantageously 4%, and even more advantageously 4.5%.

[0038] In an advantageous embodiment, the weight percent nickel content is 0.5%, more advantageously 1%, even more advantageously 1.5%, even more advantageously 2%, even more advantageously 2.5%, even more advantageously 3%, even more advantageously 3.5%, even more advantageously 4%, and even more advantageously 4.5%. An increased weight percent of nickel in the disc brake disc increases its strength and corrosion resistance. Furthermore, nickel increases heat resistance by raising the liquidus temperature of the aluminum casting alloy. P400167WO_20251027 Page 10 | 25

[0039] In an advantageous embodiment, the iron content is 0.5% by weight, more advantageously 1%, even more advantageously 1.5%, even more advantageously 2%, even more advantageously 2.5%, even more advantageously 3%, even more advantageously 3.5%, even more advantageously 4%, and even more advantageously 4.5%. An increased iron content by weight improves heat resistance by raising the liquidus temperature of the aluminum casting alloy.

[0040] In an advantageous embodiment, the weight percentage of zinc is 0.5%, more advantageously 1%, even more advantageously 1.5%, even more advantageously 2%, even more advantageously 2.5%, even more advantageously 3%, even more advantageously 3.5%, even more advantageously 4%, and even more advantageously 4.5%. An increased weight percentage of zinc increases the strength of the aluminum casting alloy.

[0041] In an advantageous embodiment, the boron content is 0.5% by weight, more advantageously 1%, even more advantageously 1.5%, even more advantageously 2%, even more advantageously 2.5%, even more advantageously 3%, even more advantageously 3.5%, even more advantageously 4%, and even more advantageously 4.5%. Boron contributes significantly to grain refinement in the aluminum casting alloy, thus reducing abrasion and consequently the formation of fine dust.

[0042] Preferably, the silicon carbide particle reinforcement has a mean particle size of at least less than 18 micrometers. The reduced particle size in the aluminum casting alloy leads to increased hardness and a further reduction in fine dust emissions. In particular, the mean particle size is at least less than 15 micrometers, advantageously less than 12 micrometers, and advantageously less than 9 micrometers, so that particularly advantageous embodiments with special hardness properties of the disc brake disc can be realized.

[0043] Depending on the size of the disc brake disc and the requirements of operation, an explicit material composition of the disc brake disc is required, whereby the material composition of the aluminium casting alloy includes the materials described here.

[0044] Preferably, the disc brake disc comprises a hub, with the friction ring extending circumferentially from the hub. The hub enables the disc brake disc to be positioned securely on a wheel axle. P400167WO_20251027 Page 11 | 25

[0045] Preferably, the hub and friction ring are formed as a single, monolithic unit. Thanks to the unique material combination and exceptionally lightweight construction, this disc brake disc is 60% lighter than steel discs. This not only improves vehicle performance but also reduces energy consumption. Unlike conventional steel or composite brakes, which are susceptible to rust and corrosion in humid or salty environments, this disc brake disc remains intact even under extreme conditions. This characteristic not only significantly extends the service life of the disc brake disc but also ensures consistent braking performance throughout its entire lifespan.

[0046] Preferably, the disc brake disc has several openings for internal ventilation. This leads to improved temperature management during braking and a reduction in weight. The low weight of this disc brake disc results in a significant reduction in the vehicle's unsprung mass. Unsprung mass refers to those parts of a vehicle that are not supported by the suspension, such as wheels, tires, brakes, and suspension components. Reducing this mass has a direct and positive impact on driving dynamics. Lighter disc brake discs reduce the inertia of the rotating mass, enabling a faster and more precise response to steering inputs. This significantly improves the vehicle's handling, especially in corners and during high-speed maneuvers.Furthermore, the lower unsprung mass reduces the load on the suspension systems, resulting in better damping and an overall more comfortable driving experience.

[0047] Preferably, at least the friction ring has a surface structure. This surface structure forms a transfer layer upon initial contact with the brake pads during the braking process. The transfer layer between the disc brake disc and the brake pad can be a key parameter for consistent braking performance and stable disc brake disc performance throughout its entire service life.

[0048] Preferably, the surface structure is obtained by an etching process. Preferably, the surface structure is obtained using a sodium hydroxide solution. This makes the transfer layer between the disc brake disc and the brake pad particularly easy to produce. P400167WO_20251027 Page 12 | 25

[0049] Preferably, the disc brake disc is available through a die casting process. Specifically, it is available through a gravity die casting process. This casting technique ensures that the silicon carbide particles are evenly distributed in the molten metal. A homogeneous particle distribution in the disc brake disc improves surface quality, braking performance, and overall performance stability. This technique also promotes a dense and pore-free aluminum casting alloy. Up to 100,000 castings can be made from a single permanent mold. However, considering the cost of mold production, a quantity of 10,000–15,000 units is generally considered the limit of economic viability.

[0050] Gravity die casting is the most cost-effective method for casting the disc brake disc in question. This is particularly significant in terms of cost for large production runs. Common equipment for gravity die casting is less complex, and initial investment and maintenance costs are lower compared to low-pressure or high-pressure casting.

[0051] Alternatively, a low-pressure die casting process can be used. In this process, a low pressure—typically 20 to 100 kilopascals—is used to fill the mold instead of gravity. Parts produced using this method exhibit high accuracy. This is due to the low pressure maintained during solidification. Therefore, the mold is filled continuously, compensating for the volume shrinkage that occurs as the molten aluminum alloy solidifies. Because of its high accuracy, it is the best method for producing axially symmetrical parts such as disc brake discs. The excellent mold filling allows for smaller stock allowances, thus minimizing material consumption. Low-pressure filling also results in good formability due to the improved flowability of the liquid aluminum alloy.Therefore, castings produced using this method have a clear contour and a smooth surface. In general, due to its high formability, the process is ideally suited for manufacturing castings with complex geometries. Because the aluminum casting alloy solidifies under pressure, it can crystallize homogeneously and form a compact structure. Therefore, castings produced using this method are solid and suitable for manufacturing parts requiring high strength. P400167WO_20251027 Page 13 | 25.

[0052] A method according to the invention for manufacturing a disc brake disc, in particular a disc brake disc as disclosed herein, comprises at least the following steps: a) Melting an aluminum alloy comprising at least aluminum, silicon, and 10.0 to 30.0 wt.% silicon carbide particle reinforcement, wherein the silicon carbide particle reinforcement has an average particle size of at least less than 30 micrometers; b) Adding titanium to the melted aluminum alloy; c) Casting the melted components into a mold for a disc brake disc using a die casting process, in particular a gravity die casting process; d) Cooling the cast disc brake disc.

[0053] The inventive process enables the production of a disc brake disc that exhibits significantly reduced particulate matter emissions during braking in a vehicle. Furthermore, this disc brake disc offers improved corrosion resistance and negligible brake noise (better noise, vibration, and harshness (NVH) behavior) in general, as well as reduced weight. This reduced weight results in a considerable improvement in the vehicle's range. A lighter vehicle requires less energy to move, which directly leads to lower energy consumption per kilometer. For electric vehicles, this translates to a longer battery range, making vehicle use more efficient. For combustion engine and hybrid vehicles, the weight reduction leads to improved fuel efficiency and reduced CO2 emissions.

[0054] In particular, the disc brake disc is manufactured in the sequence described above. Adhering to the sequence of steps in the process is especially advantageous when using elements that increase the melting point (e.g., copper, iron, titanium, nickel, magnesium, boron), as otherwise the aluminum alloy will not fully bond with these elements.

[0055] Preferably, the melting in step a) is carried out using an inductive melting process. This melting process, in which the material is arranged stepwise in a crucible and heated using an inductive heating device, P400167WO_20251027 Page 14 | 25 is particularly efficient for producing the disc brake disc according to the invention.

[0056] This prevents the reinforcing particles (e.g., SiC) from settling in the melt.

[0057] Preferably, the molten aluminum alloy is continuously stirred in step a). This prevents the reinforcing particles (e.g., SiC) from settling in the melt and ensures a homogeneous distribution in the melt pool.

[0058] Preferably, the melting temperature during the melting process according to step a) is between 750°C and 800°C. This allows for particularly efficient melting of the materials for the aluminum casting alloy, preventing the formation of carbides in the melt. Such carbides in the melt would severely impair the castability and casting behavior of the aluminum casting alloy.

[0059] Titanium and other additives that increase the melting point raise its viscosity due to the formation of intermetallic phases. These phases arise because the liquid temperature exceeds the casting temperature. Consequently, these additives are not completely dissolved in the melt, resulting in a semi-solid melt. This leads to difficult stirring, an inhomogeneous particle distribution within the melt, and impaired pouring. Furthermore, additives that lower the melting point reduce viscosity. This also presents challenges in process control—an excessively viscous melt leads to incomplete mold filling and gas inclusions. The previously described process allows for the production of disc brake discs using a casting method that avoids these problems.

[0060] Preferably, the disc brake disc is etched. In contrast to the homogeneous reaction on conventional aluminum surfaces, etching of the inventive aluminum casting alloy leads to an inhomogeneous microstructure. The aluminum matrix is ​​selectively removed, while the SiC particles remain as chemically inert islands, which can lead to microroughness, exposed particle edges, and potentially to microcracks or softening. This creates an advantageous surface structure that, in the disc brake disc's application, forms a transfer layer between the disc brake disc and the brake pad particularly easily. P400167WO_20251027 Page 15 | 25

[0061] Preferably, the disc brake disc is etched at a temperature of 20°C to 90°C. This allows the surface structure to be efficiently produced across the entire disc brake disc. Preferably, the disc brake disc is etched for up to 10 minutes. This ensures that the surface structure can be reproduced consistently.

[0062] Preferably, etching is carried out with a sodium hydroxide solution. In particular, the sodium hydroxide solution is a 10 to 50% solution. Preferably, the sodium hydroxide solution is a 20 to 30% solution. The sodium hydroxide solution facilitates the reproducible creation of the surface structure on the disc brake disc. This enables the mass production of disc brake discs with consistent quality.

[0063] The embodiments described above also apply to the following method for producing an aluminum alloy for a disc brake disc.

[0064] An inventive method for producing an aluminum alloy for a disc brake disc, in particular a disc brake disc as disclosed herein, comprises at least the following steps: a) melting an aluminum alloy comprising at least aluminum, silicon, and 10.0 to 30.0 wt.% silicon carbide particle reinforcement, wherein the silicon carbide particle reinforcement has a mean particle size of at least less than 20 micrometers; b) adding at least titanium to the melted aluminum alloy;

[0065] The inventive process enables the production of an aluminum alloy for a disc brake disc which, during operation in a braking process on a vehicle, exhibits a significantly reduced formation of fine dust emissions.

[0066] Further advantages, features and details of the invention will become apparent from the following description, in which exemplary embodiments of the invention are described with reference to the drawings.

[0067] The list of reference numerals, like the technical content of the patent claims and figures, forms part of the disclosure. The figures are described coherently and comprehensively. Identical reference numerals denote identical components. P400167WO_20251027 Page 16 | 25

[0068] Reference symbols with different indices indicate functionally identical or similar components.

[0069] The invention is explained in more detail with reference to exemplary embodiments in the following figures. The list of reference numerals forms part of the disclosure.

[0070] Positional references, such as "top", "bottom", "right" or "left", refer to the corresponding representations and are not to be understood as restrictive.

[0071] Although the invention is illustrated and described in detail by means of the figures and the accompanying description, this illustration and detailed description are to be understood as illustrative and exemplary and not as limiting the invention. It is understood that those skilled in the art may make modifications and adaptations without departing from the scope of the following claims. In particular, the invention also includes embodiments with any combination of features mentioned or shown above with regard to various aspects and / or embodiments.

[0072] The invention also includes individual features shown in the figures, even if they are shown there in conjunction with other features and / or are not mentioned above. Furthermore, the term "comprises" and derivatives thereof does not exclude other elements or steps. Likewise, the indefinite article "a" or "an" and derivatives thereof does not exclude a plurality. The functions of several features listed in the claims can be fulfilled by a single unit. The terms "essentially," "approximately," "about," and the like, in conjunction with a property or value, also define precisely that property or value. All reference numerals in the claims are not to be understood as limiting the scope of the claims.

[0073] Character description

[0074] The figures are described in a coherent and comprehensive manner. Identical reference symbols indicate identical components. (See P400167WO_20251027, page 17 of 25)

[0075] Fig. 1: a first embodiment of a disc brake disc according to the invention in a perspective view,

[0076] Fig. 2: another embodiment of a disc brake disc according to the invention in a perspective view,

[0077] Fig. 3: the disc brake disc according to Fig. 2 in a side view,

[0078] Fig. 4: the disc brake disc according to Fig. 2 in a sectional view,

[0079] Fig. 5: another embodiment of a disc brake disc according to the invention in a sectional view,

[0080] Fig. 6: a flowchart of the inventive method for manufacturing a disc brake disc according to Fig. 1, and

[0081] Fig. 7: a flowchart of the inventive process for producing an aluminium casting alloy for a disc brake disc according to Fig. 1.

[0082] Implementation of the invention

[0083] Figure 1 shows a first embodiment of an inventive disc brake disc 20 for a vehicle, comprising a friction ring 21 and a hub 22. The disc brake disc 20 consists of an aluminum casting alloy comprising 8.0 wt.% silicon, 3.5 wt.% titanium, and 13.0 wt.% silicon carbide particle reinforcement, with the remainder being aluminum, wherein the silicon carbide particle reinforcement has a mean particle size of 28 micrometers. This AISi8Ti3.5 +13 wt.% SiC disc brake disc 20 has a surface structure 23, which was produced using a 30% sodium hydroxide solution by etching the disc brake disc 20, cast by gravity die casting process, with the 30% sodium hydroxide solution for 6 minutes at 36°C.

[0084] Figures 2 to 4 show a further embodiment of an inventive disc brake disc 120, which comprises a friction ring 21 and a hub 122. The disc brake disc 120 is internally ventilated and has webs 124 and openings 125, whereby the ambient air can circulate in the openings 125. The webs 124 P400167WO_20251027 Page 18 | 25 extend radially from the inside to the outside on the disc brake disc 120. The disc brake disc 20 consists of an aluminum casting alloy comprising 9.0 wt.% silicon, 1.0 wt.% magnesium, 1.0 wt.% copper, 3.0 wt.% nickel, 2.0 wt.% iron, 1.0 wt.% titanium and 20.0 wt.% silicon carbide particle reinforcement and the remainder being aluminum, wherein the silicon carbide particle reinforcement has a mean particle size of 17 micrometers.This AISi9MgCu1 Ni3Fe2Ti1 +20 wt% SiC disc brake disc 120 has a surface structure 123 which was produced using a 25% sodium hydroxide solution by etching the disc brake disc 120 cast by gravity die casting process for 4 minutes at 55°C with the 25% sodium hydroxide solution.

[0085] Figure 5 shows a further embodiment of an inventive disc brake disc 220, which includes a friction ring 221. The disc brake disc 120 is internally ventilated and has webs 224 and openings 225, whereby the ambient air can circulate in the openings 225. The webs 224 extend largely radially from the inside to the outside on the disc brake disc 120 and have a first section 226 and a second section 227, wherein the second section 227 extends radially outwards in a different direction to the first section 226. The disc brake disc 220 consists of an aluminum casting alloy comprising 9.0 wt.% silicon, 1.0 wt.% magnesium, 1.0 wt.% copper, 1.5 wt.% boron, 1.3 wt.% titanium, and 29.0 wt.% silicon carbide particle reinforcement, with the remainder being aluminum, wherein the silicon carbide particle reinforcement has a mean particle size of 22 micrometers. This alloy is AISi9MgCu1Br1.5TH.3 +29 wt% SiC disc brake disc 220 has a surface structure 223 which was produced using a 12% sodium hydroxide solution by etching the disc brake disc 220 cast by gravity die casting process with the 12% sodium hydroxide solution for 9 minutes.

[0086] A particularly preferred embodiment of the disc brake disc comprises 1.6 ge% titanium. Compared to a disc brake disc without titanium (AMC), this exhibits an increased solidus temperature and a significantly reduced wear volume. P400167WO_20251027 Page 19 | 25

[0087] The solidus temperature increases depending on the concentration of titanium, making the disc brake disc significantly more heat-resistant. The increased hardness also significantly reduces wear. As a result, the disc brake disc emits even less fine dust.

[0088] Figure 6 shows an embodiment of the method for manufacturing the disc brake disc 20 according to Figure 1 and comprises at least the following steps: a) melting an aluminum alloy comprising at least aluminum, 8.0 wt.% silicon, and 13.0 wt.% silicon carbide particle reinforcement, wherein the silicon carbide particle reinforcement has a mean particle size of at least less than 28 micrometers; b) adding 3.5 wt.% titanium to the melted aluminum alloy; c) casting the melted components into a mold for a disc brake disc in a gravity die casting process; d) cooling and solidifying the cast disc brake disc 20.

[0089] Subsequently, in step e), the disc brake disc 20 is etched, creating a surface structure that facilitates the formation of a transfer layer between the disc brake disc 20 and the brake pad during use. A 30% sodium hydroxide solution is used to etch the disc brake disc 20 for 6 minutes at 36°C.

[0090] In an embodiment not shown, instead of step c), the molten components are cast into a mold for a disc brake disc using a low-pressure die casting process. P400167WO_20251027 Page 20 | 25

[0091] Figure 7 shows an embodiment of the method for producing an aluminum alloy for a disc brake disc 120 according to Figures 2 to 4 and comprises at least the following steps: a) Melting an aluminum alloy comprising at least aluminum, 9.0 wt.% silicon, and 20.0 wt.% silicon carbide

[0092] a) has particle reinforcement, wherein the silicon carbide particle reinforcement has a mean particle size of at least less than 17 micrometers; b) additions of 1.0 wt.% magnesium, 1.0 wt.% copper, 3.0 wt.% nickel, 2.0 wt.% iron, 1.0 wt.% titanium to the molten

[0093] Aluminum alloy.

[0094] P400167WO_20251027 Page 21 | 25

[0095] Reference symbol list

[0096] 20 disc brake disc

[0097] 21 friction ring

[0098] 22 pots

[0099] 23 Surface structure

[0100] 120 disc brake disc

[0101] 121 friction ring

[0102] 122 pots

[0103] 123 Surface structure

[0104] 124 footbridges

[0105] 125 openings

[0106] 220 disc brake disc

[0107] 221 Friction ring

[0108] 223 Surface structure

[0109] 224 footbridges

[0110] 225 openings

[0111] 226 first section

[0112] 227 second section

Claims

P400167WO_20251027 Page 22 | 25 Patent claims 1. Disc brake disc (20; 120; 220) for a vehicle or for a Wind turbine with a friction ring (21; 121; 221), wherein the Disc brake disc (20; 120; 220) is formed from an aluminium casting alloy, and the aluminium casting alloy comprises: 7.0 to 10.0 wt.% silicon; 0.25 to 5.0 wt.% titanium; 12.0 to 30.0 wt.% silicon carbide particle reinforcement and the remainder of aluminium, and wherein the silicon carbide particle reinforcement has a mean particle size of at least less than 30 micrometers.

2. Disc brake disc according to claim 1, characterized in that the aluminum casting alloy comprises at least one of the following elements: 0.5 to 5.0 wt.% copper; 0.5 to 5.0 wt.% nickel; 0.5 to 5.0 wt.% magnesium; 0.5 to 5.0 wt.% iron; 0.1 to 5.0 wt.% zinc; 0.1 to 5 wt.% boron.

3. Disc brake disc according to claim 1 or 2, characterized in that the silicon carbide particle reinforcement has a mean particle size of at least less than 18 micrometers.

4. Disc brake disc according to one of the preceding claims, characterized in that the disc brake disc (20; 120; 220) comprises a pot (22; 122), wherein the friction ring (21; 121) extends circumferentially from the pot (22; 122).

5. Disc brake disc according to claim 4, characterized in that the pot (22; 122) and the friction ring (21 ; 121) are formed as a monolithic construction in one piece.

6. Disc brake disc according to one of the preceding claims, characterized in that the disc brake disc (120; 220) has several openings (125; 225) for internal ventilation.

7. Disc brake disc according to one of the preceding claims, characterized in that at least on the friction ring (21 ; 121; 221) a surface structure (23; 123; 223) is present. P400167WO_20251027 Page 23 | 25 8. Disc brake disc according to claim 7, characterized in that the surface structure (23; 123; 223) is obtainable by an etching process, and preferably by means of a sodium hydroxide solution.

9. Disc brake disc according to one of the preceding claims, characterized in that the disc brake disc (20; 120; 220) is obtainable by a die casting process and in particular by a gravity die casting process.

10. A method for manufacturing a disc brake disc, in particular a disc brake disc (20; 120; 220) according to any one of claims 1 to 9, wherein the method comprises at least the following steps, and is manufactured in the following sequence: a) Melting an aluminum alloy comprising at least aluminum, silicon, and 12.0 to 30.0 wt.% silicon carbide particle reinforcement, wherein the silicon carbide particle reinforcement has a mean particle size of at least less than 30 micrometers; b) Adding titanium to the melted aluminum alloy; c) Casting the melted components into a mold for a disc brake disc in a die casting process, in particular in a gravity die casting process; d) Cooling the cast disc brake disc.

11. Method for manufacturing a disc brake disc according to claim 10, characterized in that the melting in step a) is carried out using an inductive melting process.

12. Method for manufacturing a disc brake disc according to claim 10 or 11, characterized in that the molten aluminium alloy is continuously stirred in step a).

13. Method for manufacturing a disc brake disc according to one of claims 10 to 12, characterized in that the melting temperature during melting according to step a) is between 750°C and 800°C.

14. Method for manufacturing a disc brake disc according to one of claims 10 to 13, wherein the disc brake disc is etched. P400167WO_20251027 Page 24 | 25 15. Method for manufacturing a disc brake disc according to claim 14, characterized in that the disc brake disc is etched at a temperature of 20°C to 90°C.

16. Method for manufacturing a disc brake disc according to claim 14 or 15, characterized in that the disc brake disc is etched for up to 10 minutes.

17. Method for manufacturing a disc brake disc according to claims 14 to 16, characterized in that the etching is carried out with a sodium hydroxide solution, wherein in particular the sodium hydroxide solution is a 10 to 50%, preferably a 20 to 30% sodium hydroxide solution.

18. A method for producing an aluminum casting alloy for a disc brake disc, in particular a disc brake disc (20; 120; 220) according to any one of claims 1 to 9, wherein the method comprises at least the following steps, and in particular is produced in the following sequence: a) melting an aluminum alloy comprising at least aluminum, silicon, and 12.0 to 30.0 wt.% silicon carbide particle reinforcement, wherein the silicon carbide particle reinforcement has a mean particle size of at least less than 30 micrometers; b) adding at least titanium to the melted aluminum alloy; 19. Method for producing an aluminium casting alloy according to claim 18, characterized in that the melting in step a) is carried out using an inductive melting process.

20. Method for manufacturing a disc brake disc according to claim 18 or 19, characterized in that the molten aluminium alloy is continuously stirred in step a).

21. Method for manufacturing a disc brake disc according to one of claims 18 to 20, characterized in that the melting temperature during melting according to step a) is between 750°C and 800°C.

Images