Brake Disc for Disk Brake and Method for Manufacturing the Same

Abstract

The present invention relates to a brake disc for a disc brake, and in particular, comprises two opposing brake surfaces (2a, 2b), each brake surface including a brake band (2) defining at least one of two main surfaces of the disc (1). The brake band (2) is made of gray cast iron or steel, preferably stainless steel. The brake disc includes a surface coating (3) covering at least one of the two brake surfaces of the brake band. The brake band (2), which at least partially defines one of the two main surfaces of the disc (1), is made of gray cast iron or steel, preferably stainless steel. The disc consists of a surface coating (3) covering at least one of the two brake surfaces of the brake band. The surface coating (3) is based on a mixture of one or more aluminum oxides and one or more titanium oxides, and the surface coating (3) is darker in color than the steel or gray cast iron of the brake band (2).

Description

Technical Field

[0001] The present invention relates to a brake disc for a disc brake and a method for manufacturing the same.

Background Art

[0002] The brake disc of a disc brake system for a vehicle or a motorcycle is composed of an annular structure or a brake band. Generally, the brake disc includes a central fixing element known as a bell, by which the disc is fixed to a rotating part of the suspension of the vehicle or the motorcycle, such as a hub. Solutions for the brake disc can also be provided that directly fix the brake band to the rotating part of the suspension, such as a hub or a wheel rim, without passing through the bell. The brake band is provided with opposing brake surfaces adapted to cooperate with friction elements (brake pads), arranged so as to straddle the brake band, and housed in at least one caliper body integral with a non-rotating component of the vehicle suspension. By the controlled interaction between the opposing brake pads and the opposing brake surfaces of the brake band, a braking action due to friction occurs, enabling the deceleration or stopping of the vehicle.

[0003]

[0004] Generally, the most common brake discs are made of gray cast iron or steel, especially stainless steel. In fact, these materials make it possible to obtain relatively low costs and good braking performance (especially from the viewpoint of wear suppression). Discs made of only carbon or carbon ceramic materials offer much better performance but are much more expensive.

[0005] ​In the market, recently, there has been an increasing need to characterize brake discs made of mouse cast iron or steel in appearance to meet the requirements of a wider range of users.

[0006] Especially among motorcycle users, there is an increasingly high need to install brake discs made of mouse cast iron or steel, especially stainless steel brake discs, with brake bands in black or blackish colors, or other darker colors.

[0007] Disk manufacturers have tried to meet such needs by coating the brake bands with a black or blackish coating.

[0008] However, a coating that can obtain a black or blackish color, or other dark color, than the base material of the brake band and can withstand high temperatures, wear, abrasion, and corrosion has not been identified so far.

[0009] That is, so far, a coating that can be applied to the brake band of a brake disc, gives a black or black-colored or other dark color than the base material of the brake disc made of gray cast iron or stainless steel, and can withstand the normal operating conditions of the disc for a long time has not been found.

[0010] Brake discs that can ensure color and performance stability in black or near-black colors, or other dark colors, are only discs made of elemental carbon or carbon ceramic materials. However, such discs are much more expensive than mouse cast iron or steel discs.

[0011] In the field of brake discs, especially for motorcycles, there is a strong desire to manufacture brake discs made of mouse cast iron or steel, especially stainless steel, coated with a black or near-black, or other dark color than the initial base material, and capable of withstanding the normal operating conditions that the disc undergoes over a long period.

Summary of the Invention

[0012] The object of the present invention is to provide a brake disc for a disc brake made of gray cast iron or steel, especially for automobiles or motorcycles, which has a black or blackish color, or other dark colors, and is provided with a brake band that can withstand the normal operating conditions that the brake disc undergoes over time.

[0013] Such drawbacks are solved by the brake disc made of gray cast iron or steel according to claim 1, and the method for manufacturing such a brake disc according to claim 17.

[0014] Other embodiments of the disc brake and manufacturing method according to the present invention are described in the following claims.

Brief Description of the Drawings

[0015] Further features and advantages of the present invention will be better understood from the following description of preferred embodiments given by way of non-limiting example.

[0016]

Fig. 1a

[0017]

Fig. 1b

[0018]

Fig. 2a

[0019]

Fig. 2b

[0020]

Fig. 3a

[0021]

Fig. 3b

[0022]

Fig. 4a

[0023]

Fig. 4b

[0024] Elements or parts of elements common to the embodiments described below are indicated using the same reference numerals.

Best Mode for Carrying Out the Invention

[0025] Referring to the foregoing figures, reference numeral 1 indicates a brake disk according to the present invention as a whole.

[0026] According to a general structural solution of the present invention shown in the accompanying drawings, the disk brake 1 consists of a brake band 2 having two opposing brake surfaces 2a and 2b, each brake surface defining at least one of the two main surfaces of the disk 1.

[0027] In particular, the brake disk 1 can be of the ventilated type.

[0028] Advantageously, the brake disk 1 can be provided with an adaptation part for fixing the disk to a vehicle.

[0029] Generally, when the brake disc is for a motorcycle, the fixed part is a wheel hub connection element called a bell. Alternatively, as shown in the attached figure, the fixed part can be composed of a plurality of appendages 4 that connect directly to the wheel hub and extend radially within the brake band, or a plurality of appendages that connect to the outermost peripheral part of the rim and extend radially outside the brake band (outer peripheral brake disc).

[0030] Generally, when the brake disc is for an automobile, the fixed part is a wheel hub connection element called a bell. Alternatively, the fixed part can also be composed of a plurality of appendices that connect to the outermost peripheral part of the rim and extend radially outside the brake band (peripheral brake disc).

[0031] The bell (if provided) of the brake disc for a motorcycle or an automobile can be made integrally with the brake band, or can be made separately and then fixed to the brake band by a suitable connecting element or other technical process (i.e., co-casting).

[0032] The fixed part of the brake disc for a motorcycle or an automobile (regardless of whether it consists of a bell or a plurality of appendages) can be made of the same material as the brake band, such as steel or gray cast iron, or another suitable material, such as an aluminum alloy. In particular, the entire disc (i.e., the brake band and the fixed part) can be made of stainless steel.

[0033] The brake band 2 is manufactured by casting. Similarly, the fixed part and / or the bell can be manufactured by casting.

[0034] Preferably, when the brake disc is for a motorcycle, the brake band with its fixed part is manufactured by punching.

[0035] Preferably, when the brake disc is for an automobile, both the brake band and the bell can be obtained by casting. Alternatively, the brake band can be obtained by blanking and the bell can be obtained by casting. Alternatively, the brake band can be obtained by casting and the bell can be obtained by deep drawing.

[0036] The fixing part can be made integrally with the brake band (as shown in the attached drawings), or can be made as a separate body mechanically connected to the brake band.

[0037] The brake band 2 is made of gray cast iron or steel, preferably stainless steel.

[0038] According to a preferred embodiment shown in the attached drawings, the brake disc 1 is a brake disc for a motorcycle. However, the brake disc 1 may be a brake disc for an automobile.

[0039] The disc 1 is provided with a surface coating 3 that covers at least one of the two braking surfaces of the brake band.

[0040] According to the invention, the surface coating 3 is based on a mixture of one or more aluminum oxides and one or more titanium oxides. Such a surface coating 3 is darker in color than the steel of the brake band 2.

[0041] Preferably, the surface coating 3 is by weight, 55% - 95% of one or more aluminum oxides; 5% - 45% of one or more titanium oxides; and 0 wt% to 40 wt% of one or more oxides selected from the group consisting of manganese oxide, iron oxide, and nickel oxide. Preferably, when one or more oxides are provided, they are MnO, Mn 2 , Mn 2 O 3 , FeO, Fe 3 O 4 , and Ni2 O 3 is selected from the group consisting of.

[0042] The aforementioned surface coating 3 can be composed of a mixture of one or more aluminum oxides and one or more titanium oxides.

[0043] In this case, the surface coating 3 preferably consists of 70% to 95% alumina (Al 2 O 3 ) by weight and the remaining titanium dioxide (TiO 2 ). More preferably, the surface coating 3 consists of 85% to 90% alumina (Al 2 O 3 ) by weight and the remaining titanium dioxide (TiO 2 ).

[0044] Alternatively, in addition to the one or more aluminum oxides and the one or more titanium oxides, the surface coating 3 may contain other metal oxides suitable for enhancing the black or blackish or other dark colors of the starting substrate that the surface coating 3 already has and consists only of a mixture of one or more aluminum oxides and one or more titanium oxides.

[0045] In this case, the surface coating 3 preferably consists of the following: - 55% to 85% by weight of one or more aluminum 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 oxide, iron oxide, and nickel oxide. Preferably, the one or more oxides are selected from the group consisting of MnO, Mn 2 , Mn 2 O 3 , FeO, Fe 3 O 4 , Ni 2 O 3 .

[0046] According to a preferred embodiment, the surface coating 3 is alumina (Al 2 O 3 ) at 70% to 85% by weight; titanium dioxide (TiO 2 ) at 10% to 25% by weight; MnO, MnO 2 , Mn 2 O 3 , FeO, Fe 3 O 4 , Ni 2 O 3 and is 5% to 20% of one or more oxides selected from the group consisting of.

[0047] In particular, the thickness of the surface coating 3 can be between 10 μm and 500 μm. Preferably, the thickness of the surface coating 3 is between 30 μm and 350 μm, and more preferably between 50 μm and 250 μm. By selecting such a range of values, an optimal balance can be achieved between the consumption of the protective coating layer and the limitation of the thermal expansion of the coating itself. In other words, if the thickness of the protective coating is less than 10 μm, when worn, it will be completely removed in a short time. On the other hand, at a thickness exceeding 500 μm, poor adhesion may occur over time due to the thermal expansion occurring during the life cycle of the disc brake.

[0048] Preferably, the surface coating 3 is a layer obtained by depositing a particulate (e.g., powder) material, and the coating is formed by one of the following deposition techniques. APS (atmospheric plasma spraying), HVOF (high velocity oxy-fuel spraying), HVAF (high velocity air fuel atomization), KM (Kinetic Metallisation), laser cladding (or laser metal deposition, LMD), or cold spray.

[0049] As is clear from comparing the photographs of FIGS. 3a and 3b with the photographs of FIGS. 4a and 4b, the surface coating 3 is darker in color than stainless steel. In particular, the surface coating 3 is black or a color close to black, or otherwise, darker in color than the starting substrate. This can also be confirmed by observing only FIGS. 3a - b, considering that the color of the coated brake band (black or a color in the black range, or darker than the starting substrate) is different from the color of the fixed part (plural appendages 4) of the uncoated brake band.

[0050] Thereby, the color of the brake band can be differentiated from the color of conventional stainless steel or gray cast iron, and the market needs can be met.

[0051] Furthermore, it has been experimentally confirmed that the surface coating 3 has a microhardness of 1100 - 1300 HV 300 This hardness value is higher than the hardness value of about 400 HV, which is typical of hardened stainless steel commonly used in the manufacture of brake disks.

[0052] Due to such a hardness value of the surface coating 3, the brake disk 1 according to the present invention has a longer service life than conventional brake disks made of hardened stainless steel without coating or gray cast iron without coating. 300 Furthermore, compared with conventional brake disks made of hardened stainless steel or gray cast iron, the brake disk 1 provided with the coated brake band according to the present invention

[0053] has been experimentally found to have high resistance to wear and abrasion,

[0054] high resistance to high temperatures,

[0055] and high corrosion resistance.

[0056]

[0057]

[0058] As shown in FIG. 2b, the surface coating 3 can be in direct contact with the braking surface of the brake band. In this case, the surface coating 3 is the only coating on the brake disc 1.

[0059] Alternatively, as shown in FIG. 2a, the brake disc 1 may include a base coating 30 disposed under the surface coating 3 and in direct contact with the braking surface of the brake band.

[0060] In this case, the brake disc 1

[0061] includes a base coating 30 that covers at least one of the two braking surfaces of the brake band and is made to be in direct contact with such a surface, and

[0062] a surface coating 3 that covers at least one of the two braking surfaces of the brake band and is formed to cover the base coating 30.

[0063] The aforementioned base coating 30 is composed of nickel and / or nickel carbide, aluminum and / or aluminum oxide, or a mixture of nickel and / or nickel carbide and aluminum and / or aluminum oxide.

[0064] Preferably, the base coating 30 is composed of 75 wt% - 95 wt% of nickel and / or nickel carbide and the remaining aluminum and / or aluminum oxide. More preferably, the base coating 30 is composed of 90 wt% - 95 wt% of nickel and / or nickel carbide and the remaining aluminum and / or aluminum oxide.

[0065] Alternatively, the base coating 30 may be composed of 100 wt% of nickel and / or nickel carbide or 100 wt% of aluminum and / or aluminum oxide.

[0066] In particular, the undercoat 30 has a thickness of from 10 μm to 500 μm, preferably from 30 μm to 350 μm, more preferably from 50 μm to 150 μm.

[0067] Preferably, the undercoat 30 is a layer obtained by depositing a particulate (e.g., powder) material and the coating is formed by one of the following deposition techniques: APS (atmospheric plasma spraying), HVOF (high velocity oxy-fuel spraying), HVAF (high velocity air fuel), KM (Kinetic Metallisation), laser cladding (or laser metal deposition, LMD), or cold spray.

[0068] Advantageously, the undercoat 30 performs a mechanical “fixing” function with respect to the surface coating 3 and instead has a coloring and wear-resistant function. In fact, the undercoat 30 formed from nickel / nickel oxide and / or aluminum / aluminum oxide has an intermediate value of the coefficient of thermal expansion between the substrate (steel or gray cast iron) and the surface coating 3 formed from one or more aluminum oxides, one or more titanium oxides, and optionally manganese oxide, iron oxide, and nickel oxide. This imparts to the undercoat 30 the ability to mitigate the difference in thermal expansion between the substrate and the surface coating 3, reducing the risk of cracks and fractures occurring in the protective surface coating 3.

[0069] With regard to the wear resistance and coloring function, the protective surface coating 3 is not affected by the presence of the protective undercoat 30.

[0070] As described above, the surface coating 3 and the undercoat 30 (if provided) cover at least one of the two braking surfaces of the brake band.

[0071] Preferably, as shown in FIGS. 2a and 2b, the brake band 2 is coated on both of its braking surfaces 2a and 2b.

[0072] In particular, the surface coating 3 and the undercoat 30 (if provided) can cover only the brake band on a single brake surface or both brake surfaces.

[0073] According to an embodiment not shown in the accompanying drawings, the surface coating 3 and the undercoat 30 (if provided) can also extend to other parts of the disc 1, such as the annular fixing portion 4 and the bell (if provided), and cover the entire surface of the disc 1. In particular, the surface coating 3 and the undercoat 30 (if provided) can cover only the fixing portion or only the bell in addition to the brake band. This choice is essentially made for aesthetic reasons, i.e., to apply a uniform color and / or finish between the whole disc or a part thereof.

[0074] One of the reasons for conveniently coating the entire brake disc 1 is to avoid corrosion / oxidation phenomena, especially those related to the contact part between the bell and the hub, which may make assembly difficult or cause defects (changes in the flatness of the mating surface).

[0075] Advantageously, at least one part of the at least one brake surface 2a or 2b covered by the surface coating 3 or the undercoat 30 (if provided) can be constituted by an activated surface having a rough profile. Such a rough profile is filled with the coating.

[0076] In particular, such a rough surface can be defined by one or more grooves or channels delimited by at least one pair of protrusions.

[0077] Such an activated surface can be obtained by subjecting the brake surface (before deposition of the coating) to a process suitable for increasing its surface roughness, such as chip removal machining, laser engraving, or plastic deformation.

[0078] In practice, the activation surface functions to increase the adhesion ability of the surface coating 3 deposited on the brake surface.

[0079] For the sake of brevity of disclosure, hereinafter, the brake disc 1 will be described together with the method according to the present invention. The brake disc 1 is, although preferably but not necessarily, manufactured by the method according to the present invention described below.

[0080] According to a general embodiment of the method according to the present invention, this method includes the following operating steps.

[0081] a) Prepare a brake disc. This brake disc includes a brake band 2 having two opposing brake surfaces 2a, 2b that at least partially define one of the two main surfaces of the disc, and the brake band is made of gray cast iron or steel, preferably stainless steel.

[0082] b) Deposit a layer of particulate material based on a mixture of one or more aluminum oxides and one or more titanium oxides on the brake disc to form a surface coating 3 covering at least one of the two brake surfaces of the brake band.

[0083] The aforementioned surface coating 3 is darker in color than the steel of the brake band 2.

[0084] Preferably, the particulate material deposited in step b) for forming the surface coating 3 consists of the following. That is, one or more aluminum oxides from 55% to 95% by weight; one or more titanium oxides from 5% to 45% by weight; and one or more oxides selected from the group consisting of manganese oxide, iron oxide, and nickel oxide from 0% to 40% by weight.

[0085] Preferably, when one or more oxides are provided, they are MnO, MnO 2, Mn 2 O 3 , FeO, Fe 3 O 4 , and Ni 2 O 3 is selected from the group consisting of.

[0086] The particulate material deposited during deposition step b) for making the surface coating 3 can consist of a mixture of one or more aluminum oxides and one or more titanium oxides.

[0087] In this case, the particulate material deposited in step b) preferably consists of 70% to 95% alumina Al 2 O 3 and the remaining titanium dioxide TiO 2 by weight. More preferably, the particulate material deposited in step b) consists of 85% to 90% alumina Al2O3 and the remaining titanium dioxide TiO 2 by weight.

[0088] Alternatively, the particulate material deposited in deposition step b) for making the surface coating 3 may contain, in addition to the one or more aluminum oxides and the one or more titanium oxides described above, other metal oxides suitable for enhancing the black or blackish or other dark color of the starting substrate that already characterizes the surface coating 3 consisting only of a mixture of one or more aluminum oxides and one or more titanium oxides.

[0089] In this case, the particulate material deposited in step b) preferably consists of the following. - 55% to 85% by weight of one or more aluminum 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 oxide, iron oxide, and nickel oxide. Preferably, the one or more oxides are MnO, MnO 2 , Mn 2 O 3 , FeO, Fe3 O 4 、 Ni 2 O 3 is selected from the group consisting of.

[0090] According to a preferred embodiment, the particulate material deposited in step b) consists of the following components. - 70% to 85% alumina (Al 2 O 3 ) by weight; - 10% to 25% titanium dioxide (TiO 2 ) by weight; - 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 , Ni 2 O 3 .

[0091] Advantageously, the surface coating 3 obtained at the end of step b) of the deposition is black or blackish or otherwise darker than the starting substrate.

[0092] Advantageously, the surface coating 3 obtained at the end of step b) of the deposition has a microhardness between 1100 and 1300 HV 300 .

[0093] Preferably, step b) of the deposition is carried out to obtain a surface coating 3 with a thickness between 10 μm and 500 μm, preferably between 30 μm and 350 μm, more preferably between 50 μm and 250 μm.

[0094] As described above, by selecting such a range of values, an optimal balance can be achieved between the consumption of the protective coating layer and the limitation of the thermal expansion of the coating itself. In other words, if the thickness of the protective coating is less than 10 μm, when it wears, it will be completely removed in too short a time. On the other hand, a thickness exceeding 500 μm may result in incomplete adhesion over time due to the thermal expansion occurring during the life cycle of the disc brake.

[0095] Preferably, the surface coating 3 is obtained by performing step b) by any of the following deposition techniques. APS (Atmospheric Plasma Spraying); HVOF (High-Velocity Oxygen Fuel); HVAF (High-Velocity Air Fuel); KM (Kinetic Metallisation); Laser Cladding (or Laser Metal Deposition, LMD); or Cold Spray.

[0096] Advantageously, the particulate material deposited in step e) to form the surface coating 3 has a particle size in the range of 5 - 40 μm. By selecting such a range of values, a high density, hardness, and limited porosity can be imparted to the coating. The selection of such a range of values was made by balancing two conflicting needs: reduction of porosity and improvement of adhesion. Particles with a smaller particle size (and thus a smaller mass) form a less porous and denser layer, but a smaller mass means less kinetic energy during the deposition of the coating, and thus the adhesion may be lower.

[0097] The surface coating 3 can be obtained by depositing the particulate material so as to be in direct contact with the braking surface of the brake band.

[0098] Alternatively, the surface coating 3 can be obtained by depositing the particulate material on top of a previously deposited undercoat 30 on the braking surface of the brake band 2, without being in direct contact with the braking surface of the brake band.

[0099] For this purpose, the method preferably includes step c) of depositing on the disk a layer of particulate material consisting of nickel and / or nickel carbide, aluminum and / or aluminum oxide, or a mixture of nickel and / or nickel carbide and aluminum and / or aluminum oxide, thereby forming a base coating 30 that directly covers at least one of the two braking surfaces of the brake band.

[0100] In practice, such step (c) is carried out before step b) described above. The surface coating 3 is deposited on top of the base coating 30.

[0101] Preferably, the particulate material deposited in step c) for forming the base coating 30 consists of 75% to 95% nickel and / or nickel carbide by weight and the remaining aluminum and / or aluminum oxide. Preferably, the particulate material deposited in step c) consists of 90% to 95% by weight of nickel and / or nickel carbide and the remaining aluminum and / or aluminum oxide.

[0102] Preferably, step c) of deposition is carried out to obtain a base coating 30 having a thickness in the range of 10 μm to 500 μm, preferably 30 μm to 350 μm, more preferably 50 μm to 150 μm. Within such a thickness range, the base coating 30 can exert the damping effect against the aforementioned thermal distortion and helps to maintain the integrity of the surface coating 3.

[0103] Preferably, the base coating 30 is obtained by performing step c) by one of the following deposition techniques: APS (atmospheric plasma spraying); HVOF (high velocity oxy-fuel spraying); HVAF (high velocity air-fuel spraying); KM (Kinetic Metallisation); laser cladding (or laser metal deposition, LMD); or cold spray.

[0104] Advantageously, the particulate material deposited in step d) to form the undercoat 30 has a particle size of 5 to 40 μm. By selecting such a range of values, it is possible to impart high density and adhesion ability to the deposition surface to the coating. The selection of such a range of values was made by taking a balance between two conflicting needs, namely reduction of porosity and improvement of adhesion. Particles with a smaller particle size (and thus a smaller mass) form a less porous and denser layer, but the smaller mass means that the kinetic energy during the deposition process is lower, and thus potentially the adhesion is lower.

[0105] Desirably, the deposition step b) and, where possible, the deposition step c) are carried out such that the average temperature of the deposition on the part does not exceed 250°C.

[0106] Desirably, the method includes a step d) of preparing the surface on which the undercoat 30 (if provided) and the surface coating 3 are to be applied. Thus, such a step d) must be carried out before carrying out step b) or step c) (if included).

[0107] In particular, the surface treatment step d) may include a sub-step d1) of cleaning the surface with a solvent suitable for removing oil and dirt.

[0108] Desirably, the preparation step d) includes a sub-step d2) of subjecting at least one part of at least one of the brake surfaces 2a or 2b to a machining suitable for increasing its surface roughness by chip removal machining or laser engraving or plastic deformation, thereby forming an activated portion of the brake surface.

[0109] In practice, such a sub-step d2) functions to increase the adhesion ability of the undercoat 30 (if provided) or the surface coating 3 deposited on the brake surface.

[0110] In particular, such a secondary step d2) has the function of forming a rough profile on the braking surface, which profile can be defined by one or more grooves or channels delimited by at least one pair of protrusions.

[0111] Advantageously, the method may include a step e) of surface finishing of the surface coating, for example by machining (grinding, turning, brushing, etc.).

[0112] In particular, such a surface finishing of the coated disc is useful to restore the correct geometric and dimensional operating tolerances, which may be lost during the deposition processes b) and c), and also to ensure an appropriate surface roughness for optimizing the frictional contact with the friction elements.

[0113] As can be understood from the above description, the brake disc according to the present invention makes it possible to overcome the drawbacks of the prior art.

[0114] The brake disc 1 according to the present invention has a darker color than steel or gray cast iron due to the surface coating 3. In particular, the surface coating 3 has a black or near-black color, or a darker color than the starting substrate. Thereby, the color of the brake band can be distinguished from the color of conventional stainless steel or gray cast iron, and the market needs can be met.

[0115] The brake disc 1 according to the present invention has a longer service life than a conventional brake disc made of hardened stainless steel without coating, since the surface coating 3 covers at least one of the two braking surfaces of the brake band.

[0116] Compared with a conventional brake disc made of hardened stainless steel or gray cast iron, the brake disc 1 provided with the coated brake band according to the present invention

[0117] - At least on the coated surface, the starting substrate of the brake band is black or blackish or other dark colors,

[0118] - Reduction of dust emissions due to improved wear resistance and abrasion resistance,

[0119] - Higher resistance to high temperatures;

[0120] - By improving corrosion resistance, more stable working conditions are ensured over a long period.

[0121] The surface coating 3 also functions as a thermal barrier to the underlying brake band due to the advantage that the thermal conductivity of the material used for the coating is lower than that of steel or gray cast iron.

[0122] According to the present invention, compared with a brake disk made of only carbon or a carbon ceramic material and having a black or black-based color or other dark color currently on the market, a brake disk made of steel or gray cast iron and having a black or black-based color or other dark color than the starting substrate can be manufactured at a significantly lower cost.

[0123] To meet occasional specific needs, those skilled in the art can make several changes and variations to the above-described methods and brake disks, all of which are included within the scope of the invention defined by the following claims.

Claims

1. A brake disk for a disk brake, particularly for a motorcycle or an automobile, comprising a brake band (2) having two opposing brake surfaces (2a, 2b), each brake surface at least partially defining one of the two main surfaces of the disk (1), wherein said brake band (2) is made of gray cast iron or steel, preferably stainless steel, wherein said disk includes a surface coating (3) covering at least one of said two brake surfaces of said brake band, wherein said surface coating (3) is based on a mixture of one or more aluminum oxides and one or more titanium oxides, a brake disk, wherein said surface coating (3) has a darker color compared to the steel or gray cast iron of said brake band (2).

2. wherein said surface coating (3) is, from 55% to 95% by weight of one or more aluminum oxides, from 5% to 45% by weight of one or more titanium oxides, and 0% to 40% by weight of manganese oxide, iron oxide, nickel oxide, preferably MnO, MnO ２ , Mn ２ O ３ , FeO, Fe ３ O ４ , Ni ２ O ３ The brake disc according to claim 1, comprising one or more oxides selected from the group consisting of

3. the brake disk according to claim 1 or 2, wherein said surface coating (3) consists only of a mixture of one or more aluminum oxides and one or more titanium oxides.

4. The surface coating (3) is composed of 70% to 95% by weight of alumina (Al ２ O ３ ), and the remainder is titanium dioxide (TiO2). Preferably, 85% to 90% by weight is alumina (Al2O3), and the balance is titanium dioxide (TiO ２ ), the brake disc according to claim 3.

5. wherein said surface coating (3) is, from 55% to 85% by weight of one or more aluminum oxides; from 10% to 40% by weight of one or more titanium oxides; and One or more oxides in an amount of 5% to 35% by weight, the oxides being selected from the group consisting of manganese oxide, iron oxide, and nickel oxide, preferably MnO ２ , Fe ３ O ４ , Ni ２ O ３ The brake disc according to claim 1 or 2, comprising:

6. wherein said surface coating (3) is, Alumina (Al ２ O ３ ) from 70% to 85% by weight; Titanium dioxide (TiO ２ ) from 10% by weight to 25% by weight; MnO, MnO ２ , Mn ２ O ３ , FeO, Fe ３ O ４ , and Ni ２ O ３ The brake disc according to claim 5, comprising 5% to 20% by weight of one or more oxides selected from the group consisting of

7. the brake disk according to any one of claims 1 to 6, wherein said surface coating (3) has a black or near-black color, or in any case a darker color than the starting substrate.

8. The surface coating (3) has a microhardness of 1100 to 1300 HV ３００ The brake disc according to any one of claims 1 to 7, which has a microhardness of ３００ .

9. the brake disk according to any one of claims 1 to 8, wherein said surface coating (3) has a thickness of from 10 μm to 500 μm, preferably from 30 μm to 350 μm, more preferably from 50 μm to 250 μm.

10. the brake disk according to any one of claims 1 to 9, wherein said surface coating (3) is a layer obtained by a deposition technique of APS (Atmospheric Plasma Spray), HVOF (High Velocity Oxygen Fuel), HVAf (High Velocity Air Fuel), KM (Kinetic Metallization), laser cladding, or cold spray.

11. The brake disk according to any one of claims 1 to 10, wherein the surface coating (3) is in contact with the brake surface of the brake band.

12. Comprising an undercoat (30) disposed under the surface coating (3) and in direct contact with the brake surface of the brake band, The brake disk according to any one of claims 1 to 10, wherein the undercoat (30) is made of nickel and / or nickel carbide and / or aluminum and / or aluminum oxide.

13. The undercoat (30) consists of 75% to 95% by weight of nickel and / or nickel carbide and the remaining aluminum and / or aluminum oxide, The brake disk according to claim 12, preferably consisting of 90% to 95% by weight of nickel and / or nickel carbide and the remaining aluminum and / or aluminum oxide.

14. The brake disk according to claim 12, wherein the undercoat (30) consists of 100% by weight of nickel and / or nickel carbide or 100% by weight of aluminum and / or aluminum oxide.

15. The brake disk according to any one of claims 12, 13 or 14, wherein the undercoat (30) has a thickness of 10 μm to 500 μm, preferably 30 μm to 350 μm, more preferably 50 μm to 150 μm.

16. The brake disk according to any one of claims 12 to 15, wherein the undercoat (30) is a layer obtained by a deposition technique of APS (atmospheric plasma spraying), HVOF (high velocity oxy-fuel spraying), HVAf (high velocity air fuel), KM (Kinetic Metallisation), laser cladding, or cold spray.

17. The brake disk according to any one of claims 1 to 16, wherein the brake disk is a brake disk for a motorcycle.

18. A method for manufacturing a brake disk for a disk brake, particularly for a motorcycle, comprising: a) a step of preparing the brake disk, wherein the brake disk includes a brake band (2) having two opposing brake surfaces (2a, 2b). The two braking surfaces each define at least one of the two main surfaces of the brake disc, The brake band is made of gray cast iron or steel, preferably stainless steel, step, b) depositing on the brake disc a layer of particulate material based on a mixture of one or more aluminum oxides and one or more titanium oxides, forming a surface coating (3) covering at least one of the two braking surfaces of the brake band, The surface coating (3) is darker in color than the steel material of the brake band (2), step, and a method comprising.

19. The particulate material forming the surface coating (3) is 55% to 95% by weight of one or more aluminum oxides; 5% to 45% by weight of one or more titanium oxides; and One or more oxides selected from the group consisting of 0% to 40% by weight of manganese oxide, iron oxide, and nickel oxide, preferably MnO, Mn ２ , Mn ２ O ３ , FeO, Fe ３ O ４ , and Ni ２ O ３ The method according to claim 18, comprising:

20. The particulate material forming the surface coating (3) consists only of a mixture of one or more aluminum oxides and one or more titanium oxides, the method according to claim 18 or 19.

21. In order to form the surface coating (3), the particulate material deposited in deposition step b) consists of 70% to 95% alumina (Al ２ O ３ ), by weight, and the balance titanium dioxide (TiO ２ ), preferably 85% to 90% alumina (Al ２ O ３ ), by weight, and the balance titanium dioxide (TiO ２ ), according to the method of claim 20.

22. In the deposition step b) for forming the surface coating (3), the particulate material deposited is 55% to 85% by weight of one or more aluminum oxides; 10% to 40% by weight of one or more titanium oxides; and One or more oxides in an amount of 5% to 35% by weight, the oxide being selected from the group consisting of manganese oxide, iron oxide and nickel oxide, preferably MnO, MnO ２ , Mn ２ O ３ , FeO, Fe ３ O ４ and Ni ２ O ３ , the method according to claim 18 or 19.

23. In the deposition step b) for forming the surface coating (3), the particulate material deposited is 70% to 85% alumina (Al ２ O ３ ) by weight, 10% to 25% titanium dioxide (TiO ２ ) by weight 5% to 20% of MnO, MnO ２ , Mn ２ O ３ , FeO, Fe ３ O ４ , Ni ２ O ３ The method according to claim 22, comprising one or more oxides selected from the group consisting of

24. The method according to any one of claims 18 to 23, wherein the surface coating (3) has a black or blackish color, or in any case a darker color than the starting substrate.

25. The surface coating (3) has a microhardness between 1100 and 1300 HV ３００ The method according to any one of claims 18 to 24, wherein the method has a microhardness in the range of 1100 to 1300 HV

26. The method according to any one of claims 18 to 24, wherein the surface coating (3) has a thickness of 10 μm to 500 μm, preferably 30 μm to 350 μm, more preferably 50 μm to 250 μm.

27. The method according to any one of claims 18 to 26, wherein the surface coating (3) is obtained by a deposition technique of APS (atmospheric plasma spraying), HVOF (high velocity oxy-fuel spraying), HVAf (high velocity air-fuel spraying), KM (Kinetic Metallisation), laser cladding, or cold spray.

28. The method according to any one of claims 18 to 27, wherein the surface coating (3) is obtained by depositing particulate matter that directly contacts the braking surface of the brake band.

29. Step c) of depositing a layer of particulate matter consisting of nickel and / or nickel carbide and / or aluminum and / or aluminum oxide on the brake disk to form a base coating (30) that directly covers at least one of the two braking surfaces of the brake band. The method according to any one of claims 18 to 27, wherein step c) is carried out before step b) and the surface coating (3) is formed on the base coating (30).

30. The particulate matter deposited in the deposition step c) for forming the base coating (30) consists of 75% to 95% nickel and / or nickel carbide by weight and the remaining aluminum and / or aluminum oxide, preferably 90% to 95% nickel and / or nickel carbide by weight and the remaining aluminum and / or aluminum oxide. The method according to claim 29.

31. The particulate matter deposited in the deposition step c) for forming the base coating (30) consists of 100% by weight of nickel and / or nickel carbide or 100% by weight of aluminum and / or aluminum oxide. The method according to claim 29.

32. The method according to claim 29, 30 or 31, wherein the base coating (30) has a thickness of 10 μm to 500 μm, preferably 30 μm to 350 μm, more preferably 50 μm to 150 μm.

33. The method according to any one of claims 29 to 32, wherein the base coating (30) is obtained by a deposition technique of APS (atmospheric plasma spraying), HVOF (high velocity oxy-fuel spraying), HVAf (high velocity air fuel), KM (Kinetic Metallisation), laser cladding, or cold spraying.

34. The method according to any one of claims 18 to 33, including, as step d), a step of preparing the disk surface (1) before carrying out step b) or step c).

35. The method according to any one of claims 18 to 34, comprising, as step e), a step of surface finishing the surface coating (3).

Images