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EP-4532952-B1 - BRAKE DISC FOR DISC BRAKES AND METHOD FOR MAKING SUCH A DISC BRAKE

EP4532952B1EP 4532952 B1EP4532952 B1EP 4532952B1EP-4532952-B1

Inventors

  • MILANESI, ANDREA
  • MELDINI, Fabio
  • MANCINI, Alessandro

Dates

Publication Date
20260506
Application Date
20230526

Claims (15)

  1. Brake disc for disc brake, in particular for motor cycles or motor vehicles, comprising a braking band (2), provided with two opposite braking surfaces (2a, 2b), each of which at least partially defines one of the two main faces of the disc (1), the braking band (2) being made of grey cast iron or steel, preferably stainless steel, said disc comprising a surface coating (3) covering at least one of the two braking surfaces of the braking band, characterised in that said surface coating (3) is based on a mixture of one or more aluminium oxides and one or more titanium oxides, said surface coating (3) having a darker colour with respect to the steel or grey cast iron of the braking band (2) and in that said surface coating (3) consists of: - 55% to 95% by weight of one or more aluminium oxides; - 5% to 45% by weight of one or more titanium oxides; and - 0% to 40% by weight of one or more oxides selected from the group consisting of manganese oxides, iron oxides and nickel oxides, preferably MnO, MnO 2 , Mn 2 O 3 , FeO, Fe 3 O 4 and Ni 2 O 3 .
  2. Disc according to claim 1, wherein said surface coating (3) consists only of a mixture of one or more aluminium oxides and one or more titanium oxides, wherein preferably said surface coating (3) consists of 70% to 95% by weight of alumina (Al 2 O 3 ) and the remaining of titanium dioxide (TiO2), preferably 85% to 90% by weight of alumina (Al2O3) and the remaining of titanium dioxide (TiO 2 ).
  3. Disc according to claim 1, wherein said surface coating (3) consists of: - 55% to 85% by weight of one or more aluminium oxides; - 10% to 40% by weight of one or more titanium oxides; and - 5% to 35% by weight of one or more oxides selected from the group consisting of manganese oxides, iron oxides and nickel oxides, preferably MnO 2 , Fe 3 O 4 and Ni 2 O 3 . wherein preferably said surface coating (3) consists of: - 70% to 85% by weight of alumina (Al 2 O 3 ); - 10% to 25% by weight of titanium dioxide (TiO 2 ); - 5% to 20% of one or more oxides selected from the group consisting of MnO, MnO 2 , Mn 2 O 3 , FeO, Fe 3 O 4 and Ni 2 O 3 .
  4. Disc according to any one of the preceding claims, wherein said surface coating (3) has a black or blackish or in any case darker colour than the starting substrate and/or wherein said surface coating (3) has a micro-hardness between 1100 and 1300 HV 300 and/or wherein the surface coating (3) has a thickness between 10µm and 500um, and preferably between 30µm and 350µm, and even more preferably between 50µm and 250µm.
  5. Disc according to any one of the preceding claims, wherein the surface coating (3) is a layer obtained by the deposition technique APS (Atmospheric Plasma Spray), HVOF (High Velocity Oxygen Fuel), HVAF (High Velocity Air Fuel), KM (Kinetic Metallization), laser cladding or cold spray.
  6. Disc according to any one of the preceding claims, wherein the surface coating (3) is in contact with the braking surface of the braking band.
  7. Disc according to any one of claims 1 to 5, comprising a base coating (30) which is arranged below said surface coating (3) and is in direct contact with the braking surface of the braking band, said base coating (30) consisting of nickel and/or nickel carbides and/or aluminium and/or aluminium oxides, wherein preferably the base coating (30) consists of: - either 75% to 95% by weight of nickel and/or nickel carbides and the remaining of aluminium and/or aluminium oxides, preferably 90% to 95% by weight of nickel and/or nickel carbides and the remaining of aluminium and/or aluminium oxides - or 100% by weight of nickel and/or nickel carbides or 100% by weight of aluminium and/or aluminium oxides; and/or wherein preferably the base coating (30) has a thickness between 10µm and 500um, and preferably between 30µm and 350µm, and even more preferably between 50µm and 150µm; and/or wherein preferably the base coating (30) is a layer obtained by the deposition technique APS (Atmospheric Plasma Spray), HVOF (High Velocity Oxygen Fuel), HVAF (High Velocity Air Fuel), KM (Kinetic Metallization), laser cladding or cold spray.
  8. Method for making a brake disc for disc brakes, in particular for motorcycles, comprising the following operating steps: a) preparing a brake disc, comprising a braking band (2) provided with two opposite braking surfaces (2a, 2b), each of which at least partially defines one of the two main faces of the disc, the braking band being made of grey cast iron or steel, preferably stainless steel; b) depositing on the brake disc a layer of particulate material based on a mixture of one or more aluminium oxides and one or more titanium oxides, forming a surface coating (3) covering at least one of the two braking surfaces of the braking band, said surface coating (3) having a darker colour with respect to the steel of the braking band (2), characterised in that the particulate material forming said surface coating (3) consists of: - 55% to 95% by weight of one or more aluminium oxides; - 5% to 45% by weight of one or more titanium oxides; and - 0% to 40% by weight of one or more oxides selected from the group consisting of manganese oxides, iron oxides and nickel oxides, preferably MnO, MnO 2 , Mn 2 O 3 , FeO, Fe 3 O 4 and Ni 2 O 3 .
  9. Method according to claim 8, wherein said particulate material forming said surface coating (3) consists only of a mixture of one or more aluminium oxides and one or more titanium oxides, wherein preferably said particulate material deposited in the deposition step b) to make the surface coating (3) consists of 70% to 95% by weight of alumina (Al 2 O 3 ) and the remaining of titanium dioxide (TiO 2 ), preferably 85% to 90% by weight of alumina (Al 2 O 3 ) and the remaining of titanium dioxide (TiO 2 ).
  10. Method according to claim 8, wherein the particulate material deposited in the deposition step b) to make the surface coating (3) consists of: - 55% to 85% by weight of one or more aluminium oxides; - 10% to 40% by weight of one or more titanium oxides; and - 5% to 35% by weight of one or more oxides selected from the group consisting of manganese oxides, iron oxides and nickel oxides, preferably MnO, MnO 2 , Mn 2 O 3 , FeO, Fe 3 O 4 and Ni 2 O 3 , wherein preferably the particulate material deposited in the deposition step b) to make the surface coating (3) consists of: - 70% to 85% by weight of alumina (Al 2 O 3 ), - 10% to 25% by weight of titanium dioxide (TiO 2 ); - 5% to 20% of one or more oxides selected from the group consisting of MnO, MnO 2 , Mn 2 O 3 , FeO, Fe 3 O 4 and Ni 2 O 3 .
  11. Method according to any one of claims 8 to 10, wherein said surface coating (3) has a black or blackish or in any case darker colour than the starting substrate and/or wherein said surface coating (3) has a micro-hardness between 1100 and 1300 HV 300 and/or wherein the surface coating (3) has a thickness between 10µm and 500um, and preferably between 30µm and 350µm, and even more preferably between 50µm and 250µm.
  12. Method according to any one of claims 8 to 11, wherein the surface coating (3) is obtained by the deposition technique APS (Atmospheric Plasma Spray), HVOF (High Velocity Oxygen Fuel), HVAF (High Velocity Air Fuel), KM (Kinetic Metallization), laser cladding or cold spray.
  13. Method according to any one of claims 8 to 12, wherein the surface coating (3) is obtained by depositing the particulate material in direct contact with the braking surface of the braking band
  14. Method according to any one of claims 8 to 12, comprising a step c) of depositing on the disc a layer of particulate material consisting of nickel and/or nickel carbides and/or aluminium and/or aluminium oxides, forming a base coating (30) covering at least one of the two braking surfaces of the braking band in direct contact therewith, wherein said step c) being conducted before said step b), said surface coating (3) being formed above said base coating (30) wherein preferably the particulate material deposited in the deposition step c) to make the base coating (30) consists of: - either 75% to 95% by weight of nickel and/or nickel carbides and the remaining of aluminium and/or aluminium oxides, preferably 90% to 95% by weight of nickel and/or nickel carbides and the remaining of aluminium and/or aluminium oxides - or 100% by weight of nickel and/or nickel carbides or 100% by weight of aluminium and/or aluminium oxides and/or wherein the base coating (30) has a thickness between 10µm and 500µm, and preferably between 30µm and 350µm, and even more preferably between 50µm and 150µm and/or wherein the base coating (30) is obtained by the deposition technique APS (Atmospheric Plasma Spray), HVOF (High Velocity Oxygen Fuel), HVAF (High Velocity Air Fuel), KM (Kinetic Metallization), laser cladding or cold spray.
  15. Method according to any one of claims 8 to 14, comprising a step d) of preparing the disc surface (1) before carrying out step b) or step c) if envisaged and/or comprising a step e) of surface finishing said surface coating (3).

Description

Field of application The present invention relates to a brake disc for disc brakes and to a method for making such a brake disc. Background art WO 2009/026458 A1 discloses a brake disk for a brake device, with a disk body with oppositely directed surfaces comprising a set of spaced and raised island formations, where each raised island formation has outer friction surface to contact brake pad A brake disc of a disc braking system of a vehicle or motorcycle comprises an annular structure or braking band. Generally, the brake disc is provided with a central fixing element, known as the bell, by means of which the disc is fixed to the rotating part of a suspension of a vehicle or motorcycle, e.g., a hub. Brake disc solutions can be provided, in which the braking band is fixed directly onto the rotating part of the suspension, e.g., a hub or wheel rim, without the interposition of a bell. The braking band is provided with opposing braking surfaces adapted to cooperate with friction elements (brake pads), housed in at least one calliper body placed straddling such a braking band and integral with a non-rotating component of the vehicle suspension. The controlled interaction between the opposite brake pads and the opposite braking surfaces of the braking band results in braking action by friction which allows the deceleration or stopping of the vehicle. In many cases, especially in motorcycles, but also in motor vehicles provided with rims with large windows and/or large diameter, the brake disc is clearly visible from the outside of the vehicle, so as to increasingly take an aesthetic value for the users. Generally, the most common brake discs are made of grey cast iron or steel, in particular stainless steel. Indeed, these materials allow obtaining good braking performance (especially in terms of wear limitation) at a relatively low cost. Discs made of carbon alone or carbon ceramic materials offer much greater performance but at a much higher cost. The market has also recently seen a growing need to aesthetically characterize grey cast iron or steel brake discs, in order to meet the demands of an increasingly wide range of users. There is an increasingly popular need among users, in particular of motorcycles, to install brake discs made of grey cast iron or steel, particularly stainless steel, with a braking band having a black or blackish or otherwise darker colour than the starting substrate. Disc manufacturers have attempted to meet such a need by coating the braking bands with black or blackish-coloured coatings. However, a coating that allows obtaining a black or blackish or otherwise darker colour than the starting substrate of the braking band while being resistant to high temperatures, wear, abrasion, and corrosion has not yet been identified until now. In other words, until now, no coating has been found that can be applied to the braking band of brake disc made of grey cast iron or stainless steel which will give it a black or blackish or otherwise darker colour than the starting substrate and will withstand the normal operating conditions of the disc over time. The only brake discs having black or blackish or otherwise darker colour than the starting substrate which ensure the stability of colour and performance are discs made of carbon alone or carbon ceramic materials. However, such discs have much higher costs than grey cast iron or steel discs. In the field of brake discs, in particular for motorcycles, the need is strongly felt to make brake discs having a braking band made of grey cast iron or steel, in particular stainless steel, provided with a coating having a black or blackish or otherwise darker colour than the starting substrate and which can withstand the normal operating conditions to which the disc is subjected over time. OVERVIEW OF THE INVENTION It is the object of the present invention to provide a brake disc for disc brakes made of grey cast iron or steel, in particular for motor vehicles or motorcycles, which has a braking band with a black or blackish or otherwise darker colour than the starting substrate and which can withstand the normal operating conditions to which the brake disc is subjected over time. Such drawbacks are solved by a brake disc made of grey cast iron or steel according to claim 1 and by a method for making such a brake disc according to claim 17. Other embodiments of the disc brake and of the making method according to the invention are described in the following claims. DESCRIPTION OF THE DRAWINGS Further features and advantages of the present invention will be more comprehensible from the following description of preferred embodiments thereof, given by way of non-limiting examples, in which: figure 1a shows a top plan view of a disc brake according to an embodiment of the present invention;figure 1b shows a section view of the brake disc in figure 1 taken along the section plane A- A indicated thereon;figure 2a shows figure 1b with some parts illustrated o