Forming material and method for producing the same

Abstract

The present invention relates to a molding material including an inner layer made of a carbon-based material and respective outer layers made of a carbon ceramic material composed of carbon and silicon carbide. Preferably, the molding material is molded to form a disk brake disk.

Description

Technical Field

[0001] The present invention relates to a molding material, a disk brake disk made from the molding material, and a method for manufacturing the molding material.

Background Art

[0002] The use of disk brake disks made of carbon-based materials, so-called "carbon-carbon" or "C / C", is known. These are composite materials composed of a carbon matrix in which reinforcing carbon fibers are oriented.

[0003] Disks made of "C / C" materials are obtained by a process involving the stacking of layers or sheets of carbon fibers in the form of a fabric or non-woven fabric, or the use of short fibers. It is also possible to add resin, followed by heat treatment and carbon densification treatment. The latter process can be carried out by various methods such as CVD (Chemical Vapor Deposition), CVI (Chemical Vapor Infiltration), LPI (Liquid Polymer Infiltration), PIP (Polymer Infiltration and Pyrolysis), or impregnation with resin and / or pitch, all of which result in an increase in density such as to impart suitable mechanical, thermal, and frictional properties to the material. For example, increasing the density from 2 to 6 times.

[0004] In order to function as a friction material, "C / C" materials require a high application temperature, and thus disks made of "C / C" materials are particularly suitable for use in racing and aerospace applications. Other characteristics of disks made of "C / C" materials include being lightweight and having a high thermal conductivity, which are the reasons for their suitability for the aforementioned applications.

[0005] However, disks made of "C / C" materials have the following disadvantages.

[0006] First, wear phenomena are likely to occur, especially in the brake band. Such wear phenomena not only inevitably affect the durability of the disk, but also lead to the emission of carbon fine particles into the atmosphere, which has an adverse effect on the environment and the human body.

[0007] Furthermore, since such disks can only be used in combination with carbon pads, their applications are limited.

[0008] It is also well known to use only carbon ceramic as the material for disk brake disks. This overcomes the drawbacks of "C / C" material disks, has excellent durability, hardly exhibits wear phenomena, and can be combined with a wider range of pads. This is usually used for high-performance road use.

[0009] However, disks made of carbon ceramic materials first lose the advantageous feature of lightness associated with "C / C" materials. Furthermore, disks made of carbon ceramic materials are more difficult to process and require a simpler shape than disks made of "C / C" materials.

[0010] Therefore, the problem to be solved by the present invention is to provide a molding material and a disk brake disk having the advantageous features of both disks made of "C / C" materials and disks made of carbon ceramic materials, and a manufacturing method that can easily achieve it.

Summary of the Invention

[0011] The above problems are solved by a shaped material, its manufacturing method, and a disk brake disk made from the shaped material as outlined in the appended claims. The definition of the claims constitutes an essential part of this specification.

[0012] The present invention first provides an inner layer made of a carbon-based material called "carbon-carbon" or "C / C", and outer layers made of a carbon ceramic material containing carbon and silicon carbide, namely a first outer layer and a second outer layer, and relates to a molding material.

[0013] The present invention next relates to a disk brake disk made from the molding material, and the disk brake disk A first brake band formed by the first outer layer of the molding material, the first brake band being delimited by a first brake surface intended to cooperate with a brake pad and a corresponding inner surface, the first brake band; A second brake band formed by the second outer layer of the molding material, the second brake band being delimited by a second brake surface intended to cooperate with a brake pad and a corresponding inner surface, the second brake band; A disk core formed by the inner layer of the molding material, the disk core extending between the inner surfaces of the first brake band and the second brake band, including.

[0014] The present invention further relates to a method for manufacturing the molding material, which sequentially includes the following steps. a) Prepare a carbon densification (concentration) blank of "C / C" material. This blank has two opposing surfaces, which are a first surface and a second surface, respectively. b) Optionally, create air passages and / or supply passages that characterize the disc brake disc. c) Contact the first surface and the second surface of the blank of the "C / C" material with increased carbon density with silicon simultaneously or sequentially, and at least a part of the silicon penetrates into the blank from the first surface at a predetermined thickness ("first thickness") and from the second surface at a predetermined thickness ("second thickness"), thereby obtaining a molding material including the first outer layer and the second outer layer made of a carbon ceramic material composed of carbon and silicon carbide. d) Optionally, perform finishing on the molding material obtained in step c).

[0015] The molding material according to the present invention, and the corresponding disk brake disk, advantageously have the typical lightness, thermal conductivity, and workability of "C / C" materials, while exhibiting higher wear resistance, significantly reducing the emission of particulate matter into the atmosphere, and having a favorable impact on the environment and human health. Furthermore, the disks of the present invention can be advantageously used with a wider range of pads, such as sintered metal pads and ceramic matrix pads.

[0016] Further features and advantages of the present invention will become more apparent from the description of some embodiments by way of non-limiting examples shown below.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0018] The present invention relates to a molding material and a disk brake disk made from the molding material, wherein a brake band (the outer peripheral surface thereof, i.e., the so-called brake surface, is adapted to cooperate with the pads of the disk brake) is made of a carbon ceramic material containing carbon and silicon carbide, and the core of the disk defined by the inner surface of the brake band is made of a "C / C" carbonaceous material.

[0019] Since the brake band that defines the tribologically active part of the disk is made of a carbon ceramic material, it has high mechanical strength and improved wear resistance. As a result, the disk has a longer lifespan and reduced particulate emissions into the environment. At the same time, the disk core maintains the lightness and thermal conductivity performance characteristic of "C / C" materials, making the disk suitable for the brake systems of high-performance cars and sports cars.

[0020] Figure 1 shows a cross-section of the molding material according to the present invention. More specifically, the material is molded to form a disk brake disk, and the hole in the center of the disk is indicated by a dashed line in the cross-section of Figure 1.

[0021] The molding material in Figure 1 is generally indicated by reference numeral 1 and includes an inner layer 2 made of a carbon-based "C / C" material and two outer layers made of a carbon ceramic material containing carbon and silicon carbide (SiC), namely a first outer layer 3 and a second outer layer 4. Preferably, the outer layer 3 and the outer layer 4 have substantially the same thickness.

[0022] The first outer layer 3 forms the first brake band of the disk brake disk and is defined by a first outer surface 5 ("first brake surface") intended to cooperate with the brake pad and a corresponding inner surface 6.

[0023] The second outer layer 4 forms the second brake band of the disk brake disk and is defined by a second outer surface 7 ("second brake surface") intended to cooperate with the brake pad and a corresponding inner surface 8.

[0024] The inner layer 2 forms a disk core defined by the inner surfaces 6 and 8 of the brake band. In the inner layer 2, a ventilation passage (not shown in Figure 1) of a ventilated disk brake disk is usually formed. The ventilation passage can be formed with a disposable core, but is preferably formed by machining, so that various complex shapes and dimensions can be achieved.

[0025] Advantageously, the inner layer 2 and each of the outer layers 3, 4 extend substantially over the entire surface of the molding material 1.

[0026] According to the first embodiment, the two outer layers 3, 4 of the molding material are made of a carbon ceramic material consisting of short disordered filaments essentially containing carbon. Preferably, the filaments have a length of less than 30 mm, for example between 6 and 24 mm.

[0027] The term "filament essentially containing carbon" means a fibrous material generally produced by the pyrolysis of various products of synthetic origin, such as polyacrylonitrile (PAN) for example, or pitch.

[0028] The filaments generally consist of a fiber bundle containing 3000 to 50000 fibers, and the diameter of the single fiber is generally 8 to 10 microns.

[0029] According to the second embodiment, the two outer layers 3, 4 of the molding material are made of a carbon ceramic material consisting of spun yarns (yarns) and / or continuous long fibers (tow) essentially containing carbon, arranged to form a woven fabric and / or a non-woven fabric.

[0030] The term "continuous long fiber" means a bundle of fibers with a high ratio of length to diameter (usually exceeding 10000:1). The term "spun fiber" means a bundle of fibers spun to form a single thread.

[0031] Preferably, the carbon ceramic material of the outer layers 3, 4 contains 10 - 40% carbon fibers, preferably about 15 - 30% 30 - 70% carbon matrix, preferably about 40 - 60% 0 - 10% silicon, preferably about 0 - 5% 10 - 40% SiC, preferably 20 - 30%.

[0032] The percentages (%) are by weight.

[0033] More preferably, the carbon ceramic materials of the outer layers 3 and 4 are carbon fiber: 15 to 25% by weight, carbon matrix: 45 to 55% by weight, silicon: 3 to 4% by weight, SiC: 23 to 28% by weight, and contain.

[0034] In this specification, the term "including ~" also includes the meaning of "composed of ~" or "essentially composed of ~".

[0035] Preferably, the outer layers 3 and 4 of the carbon ceramic material have a porosity of less than 5%, less than 4%, less than 3%, or less than 2%.

[0036] Preferably, the outer layers 3 and 4 of the carbon ceramic material have a density of 1.7 g / cm 3 ~2.5 g / cm 3 or 1.8 g / cm 3 ~2.4 g / cm 3 or 1.9 g / cm 3 ~2.3 g / cm 3 is.

[0037] Preferably, the "C / C" material of the inner layer 2 consists of the following. carbon fiber: 15 to 60%, preferably 20 to 40%, carbon matrix: 40 to 85%, preferably 60 to 80%.

[0038] The percentages (%) are weight percentages.

[0039] For the purpose of the present invention, the term "including ~" also includes the meaning of "composed of ~" or "essentially consisting of ~".

[0040] Preferably, the inner layer 2 made of the "C / C" material has a porosity between 5% and 20%, or between 5% and 10%.

[0041] Preferably, the inner layer 2 made of "C / C" material has a density between 1.5 g / cm 3 and 1.9 g / cm 3 , or between 1.6 g / cm 3 and 1.8 g / cm 3 .

[0042] The porosity and density values of the inner layer 2 made of such "C / C" material are such that they impart lightness to the molding material.

[0043] The porosity of the outer layers 3, 4 and the inner layer 2 is measured in water according to the hydrostatic pressure measurement method in accordance with standard ISO 18754:2020.

[0044] The density of the outer layers 3, 4 and the inner layer 2 is measured geometrically.

[0045] Preferably, the thickness of each of the outer layers 3, 4 is at least 4%, or at least 4.5%, or at least 5% of the thickness of the molding material.

[0046] Preferably, the thickness of each of the outer layers 3, 4 does not exceed 25%, does not exceed 20%, does not exceed 15%, or does not exceed 10% of the thickness of the molding material.

[0047] According to a preferred embodiment, the thickness of each of the outer layers 3, 4 is 0.5 to 10 mm. Preferably, the thickness is at least 1 mm, or at least 2 mm, or at least 3 mm, or at least 4 mm. Preferably, the thickness does not exceed 8 mm, or does not exceed 7 mm, or does not exceed 6 mm. For example, the thickness is between 2 mm and 8 mm, or between 4 mm and 8 mm.

[0048] The above thickness values of the outer layers 3 and 4 should be intended as average values. That is, the layer does not necessarily have the same thickness across the entire surface of the molding material. For example, near the edge of the molding material, the thickness of the outer layer can be made thicker. The variation in the thickness can be on the order of about ±2 mm. This will become clearer with reference to the method for manufacturing the molding material according to the present invention, which includes the step of infiltrating silicon into the "C / C" material, as will be described below. During the infiltration step, due to the heterogeneous microstructure of the material and the edge effect in the side region of the material, the capillary phenomenon in the edge portion may cause an increase in silicon.

[0049] The outer layers 3 and 4 of the molding material that form the brake band of the disc brake are affected by wear. Therefore, the thickness of the layer must be resistant to the wear phenomenon so that the underlying "C / C" material is not exposed, and the service life of the disc must be ensured to the maximum extent. At the same time, the thickness of the layer should not be made too thick, otherwise the material will become too heavy. The above thickness value is an appropriate compromise between these two aspects.

[0050] Preferably, the thickness of the inner layer 2 is at least 50%, or at least 55%, or at least 60%, or at least 65%, or at least 70%, or at least 75% of the thickness of the molding material.

[0051] Preferably, the thickness of the inner layer 2 does not exceed 92%, does not exceed 90%, does not exceed 85%, or does not exceed 80% of the thickness of the molding material.

[0052] Advantageously, the molding material of the present invention is a monoblock. This is because it is made from a single block of "C / C" material, which will become more apparent from the following description of its manufacturing method.

[0053] The molding material of the present invention is obtained by a method according to the claims. In particular, the method sequentially includes the following steps. a) Prepare a carbon densified blank of the "C / C" material. The blank has two opposing surfaces, a first surface and a second surface, respectively. b) Optionally, create ventilation and / or supply channels characterizing the disc brake disc. c) Bring the first surface and the second surface of the blank of the "C / C" material with increased carbon density into contact with silicon. In this case, at least a part of the silicon penetrates the blank simultaneously or sequentially at a predetermined thickness (also referred to as the "first thickness" in this application) from the first surface and at a predetermined thickness (also referred to as the "second thickness" in this application) from the second surface. Thereby, a shaped material having the first outer layer and the second outer layer made of a carbon ceramic material containing carbon and silicon carbide is obtained. d) Optionally, perform finishing on the shaped material obtained in step c).

[0054] The expression "carbon densified blank of the 'C / C' material" is also referred to as "blank" or "C / C blank" in this application, and as is clear from the following description, it means a preform made of the "C / C" material that has undergone a carbon densification process.

[0055] Step a) of the inventive method

[0056] First Embodiment: According to the first embodiment, during step a), the carbon densified blank of the "C / C" material is prepared from a corresponding preform made of spun fibers (yarns) and / or continuous long fibers (tows) that essentially contain carbon and are arranged to form a woven fabric and / or a non-woven fabric. The preparation of the preform is carried out by a well-known method. An example is described in WO2019 / 180550.

[0057] According to one embodiment, step a) of preparing the carbon densified blank of the "C / C" material sequentially includes the following steps. i) Stack layers of carbon or carbon precursor fibers in the form of a woven fabric and / or a non-woven fabric to form a preform model. ii) Needle punch the superposed fiber layers to form a three-dimensional intertwined structure. iii) Optionally, carbonize the carbon precursor fibers into carbon fibers. iv) Optionally, impregnate the preform model obtained in i), ii), or iii) with resin. v) Optionally, perform heat pretreatment on the preform model obtained in any of the steps i), ii), iii), or iv). vi) The preform model obtained in step ii), iii), iv) or v) is preferably carbon densified to a material density exceeding 1.5 g / cm 3 or exceeding 1.7 g / cm 3 to form a carbon densified blank of the "C / C" material. vii) Heat treat the blank obtained in step vi).

[0058] In step i), the layer is composed of either carbon fibers (i.e., already carbonized fibers) or a precursor of such fibers (preferably PAN, pitch, or rayon), and is converted to carbon fibers during the carbonization step iii) following needle punching. Carbonization typically involves heating the fibers to a temperature between 1500 °C and 2000 °C, which varies depending on the type of precursor.

[0059] According to one embodiment, the preform model is cylindrical and has an axis parallel to the axis of superposition of the fiber layers.

[0060] The needle punching of step ii) can be carried out using a conventional method including the use of suitable needles that engage some of the fibers in the axial direction, thereby obtaining a three-dimensional structure.

[0061] The resin used in the impregnation step iv) is selected from the group consisting of, for example, phenolic resin, acrylic resin, polystyrene resin, furan resin, or cyanoester.

[0062] The heat treatments in steps v) and vii) are such as to impart a high thermal conductivity to the material. Preferably, such heat treatment consists of treatment up to a temperature between 1800 and 2550 °C in an inert atmosphere or in a vacuum furnace.

[0063] Second Embodiment According to the second embodiment, in step a), a carbon densification blank of a "C / C" material made of short disordered filaments essentially containing carbon is prepared. Here, the filaments preferably have a length of less than 30 mm, for example, from 6 mm to 24 mm. The preparation of the blank is carried out by known methods.

[0064] According to one embodiment, step a) of preparing a carbon densification blank of a "C / C" material includes sequentially performing the following steps. i) Printing short carbon fibers or carbon precursor fibers mixed with a resin to form a preform model. Here, the resin is preferably a phenolic resin, an acrylic resin, paraffin, pitch, furan resin, or polystyrene. ii) Thermally decomposing the preform model obtained in step i). iii) Subjecting the preform model obtained in step ii) to a carbon densification process, preferably to a material density exceeding 1.5 g / cm 3 or exceeding 1.7 g / cm 3 to form a carbon densification blank of a "C / C" material. iv) Subjecting the blank obtained in step iii) to a heat treatment.

[0065] During step i), fibers of carbon or a precursor of such fibers (preferably PAN, pitch, or rayon) can be shaped. The shaping step i) is preferably carried out by operating between 80 °C and 200 °C, preferably between 120 °C and 180 °C, and / or between 5 and 250 bar, preferably between 5 and 100 bar.

[0066] The preform model taken out from the mold undergoes a thermal decomposition step ii) to carbonize the binding resin. Preferably, step ii) is carried out in a conventional furnace at a temperature generally between 800 °C and 1000 °C, depending on the type of resin used. Advantageously, the thermal decomposition step ii) is carried out under a flow of an inert gas such as nitrogen or argon, preferably at a pressure of 10 to 1000 mbar, preferably 500 to 1000 mbar. The flow of the inert gas also has the function of advantageously removing the gas released by the thermal decomposition of the resin.

[0067] The heat treatment in step iv) imparts high thermal conductivity to the material and preferably includes treatment at a temperature from 1800 °C to 2550 °C in an inert atmosphere or a vacuum furnace.

[0068] According to different embodiments, the carbon densification process of a preform (the first embodiment described above) composed of spun and / or continuous fibers arranged to form a woven or non-woven fabric, and the carbon densification process of a preform (the second embodiment described above) containing short disordered filaments are carried out in different ways.

[0069] The first method becomes either CVD (Chemical Vapor Deposition) or CVI (Chemical Vapor Infiltration) by either only coating or gaseous carbon infiltration. Generally, when the material is fibrous and highly porous, it becomes chemical vapor infiltration (CVI). These methods include using a hydrocarbon mixture (such as methane or propane) and exposing the material to be treated to a mixed gas at high temperature and low pressure. The treatment temperature is in the range of 900 to 1200 °C, preferably 1000 to 1100 °C, and the treatment pressure is less than 300 mbar, preferably several tens of mbar. The hydrocarbon mixture decomposes into elemental carbon, which deposits or infiltrates into the matrix of the material to be treated. This method requires the use of a dedicated furnace and deposits a thin layer (usually several microns) on the fibers. To obtain the desired densification, it is necessary to repeat the infiltration and total coating on the fibers several cycles to coat the fibers with a thickness exceeding 10 microns (usually 20 to 30 microns).

[0070] As another method, there is a method called LPI (Liquid Polymer Impregnation) or PIP (Polymer Impregnation / Pyrolysis), in which a liquid polymer is impregnated into the matrix of the material to be treated, and then heat treatment (pyrolysis) is performed at a high temperature. As a result, the polymer deposited on the carbon fiber is carbonized. Also in this case, several steps of infiltration and pyrolysis are required before appropriate densification of the preform is obtained.

[0071] Regardless of the method used in the carbon densification step, the density of the material of the obtained blank is usually 1.5 g / cm 3 or greater.

[0072] Step b) (optional) of the method of the present invention During step b), the carbon high-density blank of the "C / C" material obtained in step a) undergoes an initial treatment, i.e., a pretreatment.

[0073] Said step b) may include a step of shaping the blank (i.e., the densified preform), during which it is cut into the substantially completed shape and dimensions of the disk brake disk. Alternatively, the shaping operation can also be performed on the individual fiber layers either before the layering step i), before the needle punching step ii), or on the needle-punched multilayer downstream of step ii). Optionally, in the case of a blank obtained from a preform made of spun and / or continuous fibers, a shaping step is performed. A preform made of short and disordered filaments can take the desired shape in an appropriate mold.

[0074] The ventilation passages and / or supply passages of the ventilated brake disk are also created during said step b). The term "supply passage" means that the bell of the disk is attached by its holes.

[0075] Step c) of the inventive method During step c) of the method for manufacturing a molding material according to the present invention, two surfaces of the carbon high-density blank of the "C / C" material optionally subjected to said step b) are brought into contact with silicon.

[0076] According to the first embodiment, the first surface and the second surface of the blank are brought into contact with silicon simultaneously. In this embodiment, silicon penetrates simultaneously to a predetermined thickness (the "first thickness") from the first surface of the blank and to a predetermined thickness (the "second thickness") from the second surface, forming two outer layers 3 and 4 of the molding material.

[0077] According to the second embodiment, the first surface and the second surface of the blank are brought into contact with silicon sequentially. That is, first, the first surface of the blank is brought into contact with silicon, whereby at least a part of the silicon penetrates the blank over a predetermined thickness (the "first thickness") from the first surface, forming the first outer layer 3 of the molding material. Next, the second surface of the blank is brought into contact with silicon, whereby at least a part of the silicon penetrates the blank over a predetermined thickness (the "second thickness") from the second surface, forming the second outer layer 4 of the molding material.

[0078] Preferably, the penetration thickness of silicon from the first surface (the "first thickness") and the second surface (the "second thickness") is at least 4%, or at least 4.5%, or at least 5% of the thickness of the blank.

[0079] Preferably, the penetration thickness of silicon from the first surface (the "first thickness") and the second surface (the "second thickness") does not exceed 25%, does not exceed 20%, does not exceed 15%, does not exceed 10% of the thickness of the blank.

[0080] Preferably, the first thickness and the second thickness are substantially the same.

[0081] According to the first embodiment (simultaneous penetration of silicon from two surfaces), step c) includes the following steps. c1) Place the blank on the first surface side on a first layer made of silicon, preferably solid silicon, and deposit a second layer made of silicon, preferably solid silicon, on the second surface of the blank, the surface opposite to the first surface. c2) Expose the blank in contact with the first and second layers made of silicon to a temperature such that at least a part of the silicon penetrates into the blank by capillary action, for the first thickness and the second thickness.

[0082] According to the second embodiment (sequential penetration of silicon from two surfaces), step c) includes the following steps. c1) Place the blank on the side of the first surface, on a first layer made of silicon, preferably on solid silicon. c2) Expose the blank placed on the first layer made of silicon to a temperature such that at least a part of the silicon penetrates into the blank by capillary action. c1-2) Place the material resulting from step c2) on the side of the second surface, preferably on a second layer made of solid silicon. c2-2) Expose the material placed on the second layer made of silicon to a temperature such that at least a part of the silicon penetrates into the material by capillary action.

[0083] In one embodiment, the layer is made of solid silicon. The layer may include one or more materials such as boron carbide (B4C) in addition to solid silicon. According to this embodiment, boron carbide is preferably present in the layer in a weight percentage of 5% to 50%, more preferably 5% to 20%.

[0084] In another embodiment, the layer is made of solid silicon.

[0085] Solid silicon is in a pure form, or in the form of a silicon / aluminum alloy or a silicon / copper alloy, and in the form of granules or powder.

[0086] Hereinafter, the term "silicon layer" is used to refer to both a layer containing solid silicon and a layer made of solid silicon.

[0087] According to one embodiment, between steps c1) and c1-2), the material is laid directly on the silicon layer. The term "directly" relates to the fact that the material is in contact with the silicon layer and there are no additional means or elements intervening between the material and the silicon layer.

[0088] According to another embodiment, between steps c1) and c1-2), the material is laid on the silicon layer via external means or elements such as a porous partition, for example felt, a pyrolyzed wood element, or a peg. In this embodiment, between steps c1) and c1-2), the material is not in contact with the silicon embedded in the layer. The material comes into contact with the silicon during the subsequent infiltration steps c2) and c2-2).

[0089] Preferably, the silicon infiltration steps c2) and c2-2) are carried out in a suitable processing chamber provided with vents for the gases released during the process.

[0090] The infiltration steps c2) and c2-bis) advantageously include an LSI (Liquid Silicon Infiltration) process in which the silicon layer is exposed to a temperature above the melting point of silicon, preferably a temperature of 1410 °C or higher, more preferably a temperature in the range of 1420 °C to 1700 °C, so that the silicon melts and infiltrates the preform to a first thickness and a second thickness by capillary action.

[0091] According to this embodiment, the processing chamber is preferably introduced into a suitable conventional furnace heated to said temperature, for example about 1500 °C. At this temperature, the silicon melts, penetrates into the pores of the surface in contact with the silicon, and reacts with a part of the carbon in the carbon fibers and / or the carbon matrix to form silicon carbide (SiC). Desirably, a part of the molten silicon reacts with the carbon to become silicon carbide (SiC), and a part of the silicon remains unreacted. The unreacted silicon solidifies in the material during the cooling stage. Both the heating up to the processing temperature and the subsequent cooling are carried out gradually. For example, it takes 8 hours or more to reach a processing temperature of about 1500 °C, and approximately the same amount of time is required to cool the infiltrated material.

[0092] Preferably, the silicon infiltration steps c2) and c2-2) are carried out under reduced pressure between 20 mbar and 150 mbar, more preferably between 80 mbar and 120 mbar.

[0093] As an alternative to the above-described process including deposition of materials on the silicon layer and infiltration of silicon by LSI, step c) of the method of the present invention may include impregnation of a blank with silicone resin. According to this alternative embodiment, the blank is immersed in a silicone resin bath on the first surface side so as to have a thickness substantially equal to the first thickness, and then subjected to an impregnation step at a maximum temperature of 80° C., a subsequent resin polymerization step at a maximum temperature of 150° C., and finally a pyrolysis step of converting the resin into a ceramic material at a temperature of 800 to 1000° C. The temperatures of impregnation and polymerization vary depending on the type of resin. Next, the obtained material is immersed in a bath of silicone resin on the side of the second surface so as to have a thickness substantially equal to the second thickness, and the same impregnation, polymerization, and pyrolysis steps are repeated.

[0094] Preferably, the amount of silicon in contact with each of the first surface and the second surface of the blank is 2% by weight or more and 15% by weight or less, 3% by weight or more and 12% by weight or less, 4% by weight or more and 10% by weight or less, or 5% by weight or more and 7.5% by weight or less based on the weight of the blank.

[0095] The amount of the silicon is an amount that ensures infiltration of silicon into the first thickness and the second thickness. In particular, the amount of the silicon is an amount necessary to at least partially fill the porosity of the "C / C" material of the blank for the thickness from the first surface equal to the first thickness and the thickness from the second surface equal to the second thickness. In particular, the amount of the silicon is an amount that does not fill the porosity of the inner layer made of "C / C" material extending between the first thickness and the second thickness.

[0096] The manufacturing method of the molding material of the present invention as described above results in a non-uniform composition throughout the thickness in two outer layers made of a carbon ceramic material. For example, in the portions near the surfaces of the two outer layers, the concentrations of silicon and silicon carbide are high and gradually decrease as the distance from the surface increases.

[0097] It has been experimentally found that the silicon with which the blank of the carbon densified "C / C" material comes into contact is completely absorbed. This means that the absorption of silicon by the blank is quantitative. Due to this advantage, it becomes possible to control the penetration thickness by adjusting the amount of silicon as well. In this regard, FIG. 2 is a graph showing the weight gain in a single infiltration step of a carbonized blank material of a "C / C" material with LSI processing on only one side (left histogram) and a blank material with LSI processing on both sides (right histogram). "Target" is the amount of silicon in contact with the surface.

[0098] The penetration thickness of silicon is monitored, for example, by analyzing the cross-section of the molding material using an SEM microscope. FIG. 3 shows two images obtained by SEM at different distances from the outer surface of the outer layer of the molding material according to the present invention, where the outer layer made of a carbon ceramic material has a thickness of about 8 mm.

[0099] FIG. 3 shows an image obtained by SEM at a distance of about 4 mm from the outer surface (upper part). It can be clearly seen that all carbon pores (dark gray) are filled with silicon and silicon carbide (light gray), and thus it can be understood that this material is a carbon ceramic.

[0100] FIG. 3 shows an SEM image of a deeper part (lower). The interface between the outer layer of the silicon-infiltrated material and the inner layer of the "C / C" material, which is at a depth of about 8 mm from the surface, can be clearly seen. This indicates that as the depth increases, the material becomes "C / C" again.

[0101] Also, through experiments, it was confirmed that the molding material of the present invention maintains substantially the same thermal conductivity as the "C / C" material (70 W / mK) at 600°C. From the perspective of heat, this means that ceramization does not significantly change the material.

[0102] Step d) (optional) of the inventive method During step (d), the material obtained in step (c) is subjected to a second treatment, i.e., finishing, during which the material is finished to the final shape and / or size of the disc brake disc. Since the shape of the molding material may be deformed by heat treatment, this final processing is often necessary. During step (d), surface deformations are removed. Such finishing is preferably carried out dry, for example using a diamond grinding wheel.

[0103] It is obvious that only one specific embodiment of the present invention has been described. For both the molding material and its manufacturing method, those skilled in the art can make all the changes necessary to adapt to specific conditions without departing from the scope of protection defined in the appended claims.

Claims

1. An inner layer (2) made of a carbon-based material called "carbon-carbon" material or "C / C" material, A molding material (1) comprising a first outer layer (3) and a second outer layer (4), which are outer layers made of carbon-based ceramic material containing carbon and silicon carbide, respectively.

2. A molding material according to claim 1, wherein the first outer layer (3) and the second outer layer (4) are made of a carbon-based ceramic material containing short, disordered filaments that are essentially made of carbon.

3. A molding material according to claim 1, wherein the first outer layer (3) and the second outer layer (4) are made of a carbon ceramic material which is made of spun fibers (yarns) and / or continuous filaments (tows) which are essentially made of carbon and which are arranged to form a woven fabric and / or a nonwoven fabric.

4. A molding material according to claim 1, The carbon-based ceramic material of the first outer layer (3) and the second outer layer (4) is 10-40% carbon fiber, Carbon matrix of 30-70%, Silicon at 0-10%, It contains 10-40% SiC, The aforementioned percentage is a weight percentage of the molding material.

5. A molding material according to claim 1, The first outer layer (3) and the second outer layer (4) have a porosity of less than 5% and / or 1.7 g / cm³. ３ 2.5g / cm or more ３ A molding material having the following density:

6. A molding material according to claim 1, The "C / C" material of the inner layer (2) is 15-60% carbon fiber, It contains 40-85% carbon matrix, The aforementioned percentage is a weight percentage of the molding material.

7. A molding material according to claim 1, The inner layer (2) has a porosity of 5% to 20% and / or 1.5 g / cm³ ３ From 1.9 g / cm ３ A molding material having a density of [value].

8. A molding material according to claim 1, A molding material in which the thickness of each of the first outer layer (3) and the second outer layer (4) is at least 4% of the thickness of the molding material and / or does not exceed 25% of the thickness of the molding material.

9. A molding material according to claim 8, wherein the thickness of each of the first outer layer (3) and the second outer layer (4) is 0.5 to 10 mm.

10. A molding material according to claim 1, A molding material in which the thickness of the inner layer (2) is at least 50% of the thickness of the molding material and / or does not exceed 92% of the thickness of the molding material.

11. A molding material according to claim 1, A molding material in which the aforementioned molding material is molded to form a disc brake disc.

12. A disc brake disc made from the molding material described in claim 1, A first brake band formed by the first outer layer (3) of the molding material, comprising a first brake surface (5) intended to cooperate with a brake pad and a corresponding inner surface (6), A second brake band formed by the second outer layer (4) of the molding material, comprising a second brake surface (7) intended to cooperate with a brake pad and a corresponding inner surface (8), A disc brake disc comprising a disc core formed by the inner layer (2) of the molding material, extending between the inner surface (6) of the first brake band and the inner surface (8) of the second brake band.

13. A method for producing the molding material described in claim 1, a) Prepare a carbon-densified blank of a "C / C" material having two opposing surfaces, which are the first and second surfaces, c) A method comprising bringing the first surface and the second surface of the carbon-densified blank of the "C / C" material into contact with silicon, simultaneously or sequentially, so that at least a portion of the silicon penetrates the carbon-densified blank from the first surface to a first thickness and from the second surface to a second thickness, thereby obtaining a molding material including the first outer layer and the second outer layer made of a carbon ceramic material containing carbon and silicon carbide.

14. The method according to claim 13, A method wherein the penetration thickness of silicon from the first surface and the second surface is at least 4% of the thickness of the carbon density blank, and / or does not exceed 25% of the thickness of the carbon density blank.

15. The method according to claim 13, In step a), the carbon-densified blank made of "C / C" material is prepared, A method wherein the carbon-densified blank comprises spun fibers (yarns) and / or continuous filament (tows) arranged to form a woven and / or nonwoven fabric, wherein the carbon-densified blank is essentially made of carbon.

16. The method according to claim 15, Step a) of preparing a carbon-densified blank of the "C / C" material is: (i) A preform model is formed by stacking layers of carbon or carbon precursor fibers in the form of woven and / or nonwoven fabrics; (ii) The steps of forming a three-dimensional entanglement structure by needle punching the superimposed layers; The process comprises one or more steps: (iii) carbonizing the carbon precursor fibers into carbon fibers; (iv) performing a step (i) or a step (ii) or a step (iii) followed by impregnating the preform model obtained in step (i) with resin; and (v) performing a step (v) performing a step (i) or a step (ii) or a step (iii) or a step (iv) followed by heat pretreatment of the preform model obtained in step (i); Step (vi), performed after step (ii), or step (iii), or step (iv), to perform a carbon densification treatment to form a carbon densification blank made of "C / C" material; A method comprising, in order, the step (vi) of heat-treating the carbon-densified blank obtained in step (vi);

17. The method according to claim 13, A method for preparing a carbon-densified blank of a "C / C" material consisting of short, disordered filaments that essentially contain carbon, in step a).

18. The method according to claim 17, wherein step a) preparing a carbon-densified blank of "C / C" material, i) A step of forming a preform model by molding short carbon fibers or carbon precursors mixed with a resin, wherein the resin is a phenolic resin, an acrylic resin, paraffin, pitch, a furan resin, or polystyrene; ii) A step of thermally decomposing the preform model obtained in step i); iii) The preform model obtained in step ii) is subjected to a carbon densification treatment to form a carbon densification blank made of "C / C" material; A method comprising the steps of: iv) subjecting the carbon-densified blank obtained in step iii) to heat treatment;

19. The method according to claim 13, A method wherein the amount of silicon in contact with the first surface and the second surface of the carbon density blank is 2% by weight or more and 15% by weight or less, relative to the weight of the carbon density blank.

20. The method according to claim 13, wherein step c) is c1) Placing the carbon-densified blank on the side of the first surface, on a first layer made of silicon or solid silicon, and depositing a second layer containing silicon or solid silicon on the second surface of the carbon-densified blank opposite to the first surface, c2) A method comprising bringing the carbon density-reduced blank into contact with the first and second layers containing silicon, and heating to a temperature such that at least a portion of the silicon penetrates the carbon density-reduced blank to the first and second thicknesses by capillary action.

21. The method according to claim 20, A method wherein step c2) includes a liquid silicon infiltration (LSI) process carried out at a temperature above the melting point of the silicon and / or at a pressure of 20 mbar to 150 mbar.

22. The method according to claim 13, wherein step c) is c1) Placing the carbon-densified blank on the first layer containing silicon or solid silicon on the side of the first surface, c2) Exposing the carbon-densified blank, which is placed on the first layer containing silicon, to a temperature such that at least a portion of the silicon penetrates the carbon-densified blank to a first thickness by capillary action, c1-2) Placing the material obtained from step c2) on the side of the second surface, on a second layer containing silicon or solid silicon, c2-2) A method comprising exposing a material placed on the second layer containing silicon to a temperature such that at least a portion of the silicon penetrates the material to the second thickness by capillary action.

23. A method according to claim 22, wherein step c2) and step c2-2) include a liquid silicon infiltration (LSI) method at a temperature above the melting point of silicon and / or a pressure between 20 mbar and 150 mbar.

24. The method according to claim 13, Step b) is performed after step a) and before step c), and is a step that creates a ventilation and / or supply passage that characterizes the disc brake disc, A method comprising step d) performing a finishing process on the molding material obtained in step c).

25. A molding material obtained by the method described in any one of claims 13 to 24.

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