Method for manufacturing friction elements

Abstract

The present disclosure relates to a method of manufacturing a friction element, the method including the steps of: providing a back plate having a connecting surface with a plurality of protrusions; providing a sintering composition, applying the sintering composition to the connecting surface, and molding the sintering composition to form an intermediate friction element; disposing the intermediate element between sintering plates; and providing a friction coefficient of 10 kg / cm. 2 ~200kg / cm 2 and applying a pressure in the range of 100° C. to 950° C. between the sintering plates while selectively applying an electric current between the sintering plates to raise the temperature to a sintering temperature in the range of 800° C. to 950° C.; and maintaining at least one of the applied pressure, the selectively applied electric current, and the sintering temperature for a sintering time in the range of 1 hour to 10 hours to form a friction material on the back plate.

Description

[Technical Field]

[0001] Friction elements and methods of manufacturing friction elements The friction elements are useful in vehicle brake systems, particularly disc brake systems, such as disc brake systems for motorcycles. [Background technology]

[0002] Brake systems employ brake pads to provide friction against moving parts. The brake pads can be pressed against the moving parts to stop motion. The brake pads in a brake system are typically placed on a carrier plate that provides the brake pads with sufficient hardness and rigidity. Brake pads can be constructed from a range of materials. Each material can be manufactured using an appropriate technique. For example, brake pads can be made from ceramic materials, organic materials such as polymers, or metal-based materials, depending on the application of the brake pad. For example, brake pads made of metal components can be manufactured using a sintering process.

[0003] When brake pads are manufactured by a sintering process, a sintering composition is applied to a carrier plate and then sintered. The sintering composition typically includes a base matrix material, an abrasive, a lubricant, fibers, fillers, and various processing aids. Each of these components can provide a function to the sintering process and to the final brake pad produced by the process.

[0004] Sintering is suitable for imparting low wear, high thermal stability, and braking performance to brake pads. For example, in motorcycles, it provides a strong initial bite, instant braking feel, easy modulation, and powerful in-stop performance. The present disclosure aims to provide an improved sintering process for manufacturing brake pads.

[0005] Sintered brake pads are typically metal-based brake pads, and ductile metals, particularly copper but also nickel, are commonly used. This is because ductility allows the brake pads to have good braking performance characteristics, such as a desired coefficient of friction during braking and other desirable properties. However, both copper and nickel are heavy metals that are environmentally undesirable. Wear of copper- or nickel-containing brake pads inevitably releases the metals into the environment.

[0006] Some attempts have been made to remove copper from brake pad materials. For example, WO 2017 / 222538 discloses a ferroalloy-based system for friction applications that can be described as substantially copper-free. However, large amounts of tin are required.

[0007] EP 0055205 addresses the problem of metal pick-up found in railway brakes, where silver from the wheel steel migrates to the brake shoe when the train brakes. This problem can be solved by including copper, manganese, or ferrochromium in sintered powder metal friction materials for railway brakes.

[0008] US2018 / 031067 discloses a friction material that does not contain more than 0.5% by weight of copper. However, because this friction material is not used in a sintering process, the resulting brake pads have undesirable porosity.

[0009] JP 2006-348379 A discloses a nickel-free sintered metal friction material that has properties equivalent to those of nickel-containing sintered metal friction materials. Several compositions are disclosed, some containing copper and some not, but these compositions have a specific ratio of iron to aluminum.

[0010] The sintering process involves at least pressure and temperature applied to the composition to be sintered, but many more parameters can be adjusted. US 4,456,578 discloses a method for making friction elements for automobile or motorcycle disc brakes. Here, an electric current is applied to the composition to be sintered. This type of process is generally referred to as conductive sintering or current-assisted sintering. All sintering compositions contain copper or environmentally undesirable metals, such as lead.

[0011] A further example of conductive sintering of substrates to provide friction elements is disclosed in US 4,576,872. All the substrates tested contain a large amount of copper, and possibly nickel and lead.

[0012] EP3569672 discloses a sintered metal friction material containing iron, nickel, zinc, tin, copper, and up to 5% of a sintering aid powder, which can be iron boride powder, iron phosphide powder, copper phosphide powder, or phosphor bronze powder.

[0013] CN109253196 discloses a brake friction pair and a preparation method thereof. The brake pad of the brake friction pair includes a friction material having iron powder, aluminum powder, ferrophosphor powder, flake graphite, low-carbon ferrochromium, zirconium oxide, aluminum oxide, and copper powder. The preparation method includes a mixing step, a pressing step, and a sintering step.

[0014] It is an object of the present disclosure to provide an improved sintering process for producing friction elements, and to provide a sintering composition suitable for the method of producing friction elements. A further object is to provide a friction element that is free of environmentally harmful heavy metals. Summary of the Invention

[0015] The present disclosure relates to a method of manufacturing a friction element, said method comprising: providing a backplate, the backplate having a connecting surface with a plurality of protrusions; Providing a sintering composition, said sintering composition comprising: 0% to 5% by weight of a friction-modifying metal; A fiber component in the range of 1% by weight to 10% by weight; 2.5 wt% to 12 wt% of a metal phosphide; a lubricant in the range of 6% by weight to 23% by weight; a filler in the range of 0% to 5% by weight; an abrasive in the range of 3% by weight to 20% by weight; Processing aids in the range of 0.2 wt.% to 2 wt.%; The remaining iron, and applying the sintering composition to the connecting surface and molding the sintering composition to form an intermediate friction element having a pre-sintered pack on the backplate; disposing one or more intermediate friction elements between the sintered carrier and the sintering vise plate with the backplate facing the sintered carrier and the pre-sintered pack facing the sintering vise plate, or with the backplate facing the sintering vise plate and the pre-sintered pack facing the sintered carrier; simultaneously carrying out the following steps: 2 ~200kg / cm 2 applying a pressure in the range of 800°C to 950°C between the sintering vise plate and the sintering carrier; and increasing the temperature between the sintering vise plate and the sintering carrier to a sintering temperature in the range of 800°C to 950°C. maintaining at least one of the applied pressure and the sintering temperature for a sintering time ranging from 1 hour to 10 hours to form a friction material on the backplate; Equipped with.

[0016] In one example, the sintering carrier is a sintering anode and the sintering vise plate is a sintering cathode, and an electric current is applied between the sintering cathode and the sintering anode to raise the temperature to the sintering temperature, and at least one of the applied electric current, the applied pressure, and the sintering temperature is maintained for the sintering time. For example, the applied electric current and at least one of the applied pressure and the sintering temperature can be maintained for the sintering time. Alternatively, the sintering carrier can be the sintering cathode and the sintering vise plate can be the sintering anode. Thus, for example, the method includes the steps of: placing one or more intermediate friction elements between the sintering anode and the sintering cathode, with a backplate facing the sintering anode and a pre-sintered pack facing the sintering cathode, or with a backplate facing the sintering cathode and a pre-sintered pack facing the sintering anode; and simultaneously performing the following steps, wherein these steps are performed at a pressure of 10 kg / cm or less: 2 ~200kg / cm 2 applying a pressure in the range of 0.25 to 1.50 between a sintering cathode and a sintering anode, and applying an electric current between the sintering cathode and the sintering anode to raise the temperature to a sintering temperature in the range of 800°C to 950°C; and maintaining at least one of the applied pressure, the applied electric current, and the sintering temperature for a sintering time in the range of 1 hour to 10 hours to form a friction material on the backplate.

[0017] In the context of this disclosure, the term "sintered composition" refers to the material that is subjected to the present process to form the friction material. Correspondingly, the term "friction material" refers to the material on the backplate of the friction element produced in the present process.

[0018] The method involves the simultaneous application of pressure and sintering temperature, and may also involve the application of electric current. In the context of this disclosure, this process is referred to as "sintering." When electric current is applied, the process is referred to as "conductive sintering." In the sintering process, heat and / or pressure is applied to the particulate material, the purpose of which is to fuse the particles together. In this context, conductive sintering refers to the application of pressure, e.g., 10 kg / cm, to the sintered composition. 2 ~200kg / cm 2 This means that the sintered composition is heated by applying a pressure in the range of kg / cm and an electric current to the sintered composition. The temperature may be increased by means other than the application of an electric current, for example, by heating in an oven or by using intermediate friction elements or heating elements that are not electrically connected to the sintered stack. 2 However, pressure may be expressed in other units such as bar or MPa. 2 While calculating pressure in bar or MPa from pressure in MPa is well known to those skilled in the art, pressures typically range from 0.98 MPa to 19.6 MPa, or from 9.8 bar to 196 bar. In this method, a sintering temperature in the range of 800°C to 950°C is selected, and an electric current is applied to raise the temperature to the selected sintering temperature. The sintering anode, intermediate friction element, sintering cathode, and any additional elements, such as additional conductive materials, collectively have a resistance, and the resistance and the relationship between current and voltage are determined from the resistance. The current, i.e., the combination of voltage and current determined by the resistance, can be freely selected, but typically the current is an alternating current with a voltage of up to 400 V and a current of up to 300 A. However, it is also contemplated that the current may have a pressure greater than 400 V and / or a current greater than 300 A. Similarly, it is also contemplated that the current may be a direct current, such as a pulsed direct current. The frequency of the alternating current can be freely selected, but is typically in the range of 10 Hz to 10 MHz.

[0019] In this method, a sintering carrier and a sintering vise plate are employed. When an electric current is employed, the sintering carrier is referred to as a sintering anode, and the sintering vise plate is referred to as a sintering cathode. Alternatively, the sintering carrier may be a sintering cathode, and the sintering vise plate may be a sintering anode. The sintering anode and the sintering cathode may be collectively referred to as sintering electrodes. The terms "anode" and "cathode" are used to distinguish the electrodes with respect to their relative arrangement and the arrangement of the intermediate friction element. In particular, an electric current is applied to the sintering anode and the sintering cathode. This current is not limited to direct current and may be alternating current. In this context, the sintering anode may be referred to as a first sintering electrode, and the sintering cathode may be referred to as a second sintering electrode. Correspondingly, the sintering carrier and the sintering vise plate may be referred to as "sintering plates."

[0020] The temperature may be raised to the sintering temperature using an external heat source, e.g., by using an external heat source without using an electric current, or by using an external heat source alone, e.g., by combining an electric current with additional external heating, e.g., from an external heat source. In this context, external heating can be obtained by using any external heat source. The term "external heating" generally refers to heat obtained using any desired heat source. For example, in addition to applying an electric current to the intermediate friction element or sintering stack, these may be placed in an oven, etc. Thus, if the method does not employ external heating, the temperature is raised by applying an electric current between the sintering cathode and the sintering anode. In one example, no additional external heating is used. For example, the temperature may be raised to a temperature higher than, for example, ambient temperature using only an electric current. In this context, ambient temperature is any temperature in the range of 5°C to 50°C. If the temperature is raised using only an electric current and no additional external heating is employed to raise the temperature above ambient temperature, the sintering is easier to control than a sintering process using only external heating or a sintering process using a combination of external heating and heating by electric current.

[0021] In a preferred example, multiple intermediate friction elements are placed between sintering plates, i.e., between sintering electrodes. When using sintering electrodes, it is preferable not to employ additional external heating to raise the temperature above ambient temperature. When multiple intermediate friction elements are placed between sintering electrodes, each of the multiple intermediate friction elements is subjected to the same sintering conditions. This is because the sintering temperature is obtained from the current flowing through the sintering electrodes and, therefore, the current passing through each of the friction elements. This makes it easier to control the sintering conditions and ensures that multiple friction elements of the same quality are produced. For example, multiple intermediate friction elements can be placed between sintering electrodes with three or more rows of intermediate friction elements, each row having three or more intermediate friction elements between the sintering electrodes.

[0022] In a specific example, multiple intermediate friction elements are arranged in two or more layers of the sintering stack, with each layer separated by a plate made of conductive material. Heating is achieved using at least an electric current. Separating the layers with plates made of conductive material ensures that all intermediate friction elements receive the same electric current. A preferred conductive material is a carbon-based material, such as graphite. Carbon-based materials not only have electrical conductivity but also function as a thermal barrier. This improves temperature uniformity between different layers in the sintering stack. For example, if the conductive material is carbon fiber-reinforced carbon, temperature variations within the sintering stack, such as between layers in the sintering stack, can be limited to within 5% or 3% of the desired sintering temperature. Because the temperature is raised to the sintering temperature using an electric current, each layer receives the same sintering temperature, and each intermediate friction element experiences the same sintering conditions. It is particularly preferred not to employ additional external heating to raise the temperature above ambient temperature.

[0023] In this method, the applied pressure and / or the sintering temperature are maintained for a sintering time ranging from 1 hour to 10 hours to form the friction material on the backplate. When an electric current is employed, the electric current and / or the applied pressure and / or the sintering temperature are maintained for a sintering time ranging from 1 hour to 10 hours to form the friction material on the backplate. Generally, a temperature is considered to be the sintering temperature as long as it is maintained in the range of 800°C to 950°C. However, the sintering temperature can be any temperature in the range of 800°C to 950°C. In one example, a sintering temperature of, for example, 825°C, 850°C, 875°C, 900°C, or 925°C is selected, and the temperature is considered to be the sintering temperature as long as it is within 50°C of the selected sintering temperature. Preferably, the temperature is raised to the sintering temperature by the electric current without the use of additional external heating. It is also preferred that the applied electric current and pressure are maintained for the sintering time. In this context, the sintering time begins when the sintering temperature is reached. For example, if the temperature is ambient, pressure can be applied, e.g., before using an electric current to raise the temperature and maintain it at the beginning and during the sintering period. In certain examples, the temperature is raised to the sintering temperature by the electric current without additional external heating, and once the sintering temperature, e.g., a selected sintering temperature, is reached, the electric current is adjusted to maintain the temperature at the sintering temperature. For example, the temperature can be monitored, and the electric current can be adjusted in a feedback loop to maintain the temperature at the sintering temperature, e.g., the selected sintering temperature ±50°C, ±40°C, ±30°C, ±25°C, ±20°C, ±15°C, ±10°C, or ±5°C. Once the sintering period is over, the temperature is reduced to ambient. Generally, pressure is maintained until the temperature reaches a predetermined temperature limit, e.g., a temperature below 200°C.

[0024] The friction element includes a backplate and a friction material. The friction element is useful in vehicle braking systems. In vehicle braking systems, the friction material of the friction element presses against a rotating rotor, creating friction to stop the rotor from rotating, but the friction element can also be used to stop a stationary rotor from rotating. Typically, the rotor has an annular shape. It is also contemplated that the rotor may have a disk shape. The annular or disk body has a center with an axis, and the annular or disk body may lie in a plane perpendicular to this axis. The annular body can generally be represented by two concentric curves. For example, the annular body can be represented by two concentric circles. A disk body can similarly be represented as curvature around a center. The annular body has an inner surface and an outer surface in a plane perpendicular to the axis of the annular body.

[0025] Friction elements are typically mounted in braking systems to maximize the contact area between the friction material and the inner or outer surface of the rotor when the braking system is activated to stop the rotor from rotating. Braking systems may also include two friction elements: one mounted on the friction material and pressed against the inner surface of the rotor, and the other mounted on the friction material and pressed against the outer surface of the rotor. In particular, the two friction elements may be mounted in the same position in a plane perpendicular to the axis of the annulus.

[0026] The rotor has a direction of rotation. The dimensions of the friction element may be defined relative to the direction of rotation. Thus, the friction element, and therefore the backplate, has a "front end" and an "rear end" defined by the direction of rotation. The direction from the front end to the rear end defines the braking direction of the friction element. The direction of rotation is represented by the circumference of a circle, while the braking direction is a straight line. As a result, the braking direction does not overlap with the direction of rotation. However, the direction of rotation also defines the tangential direction of rotation. Generally, the braking direction does not deviate from the tangential direction of rotation by more than 20°, depending on the rotor dimensions.

[0027] In this method, a sintering composition is applied to the connecting surface of the backplate. The sintering composition is summarized in Table 1.

[0028] [Table 1]

[0029] All sintering composition ingredients are provided as percentages (wt%) based on the weight of the sintering composition. Table 1 shows exemplary ingredients, but it should be understood that any number of constant ingredients may be used for each ingredient. For example, a friction modifier metal may include one or more different metals, a lubricant may include one or more different lubricant ingredients, etc. In the context of this disclosure, weight is dry weight for solid ingredients and weight of the ingredient at ambient conditions for liquid ingredients. Weight may also be referred to as mass. During sintering, processing aids are lost and the relative content is adjusted accordingly.

[0030] All components, except for the liquid component, are provided as powders. The powders are generally micro-sized. For example, the particles have sizes ranging from 1 μm to 100 μm. The particles can have any size and shape distribution. Generally, the particles used in the present method are sized, e.g., sieved, before use. Also, the particles are typically classified only at the upper end of the size range. However, it should be understood that the particles used in the present method have a lower size limit of 1 μm unless otherwise specified. Furthermore, size sizing can involve the removal of smaller particles. This results in the particles used being a size fraction from which both larger and smaller particles have been removed. For example, the size can be 1 μm to 1000 μm. The sintering composition should be thoroughly mixed before applying it to the backplate.

[0031] The sintered composition includes iron, which provides a metal matrix. The metal matrix is ​​the main component of the sintered composition. Generally, the sintered composition includes at least 40% by weight of iron, e.g., at least 45% by weight of iron, e.g., at least 50% by weight of iron, e.g., at least 55% by weight of iron, or at least 60% by weight of iron. The iron is typically at least 99% pure iron, but it is also contemplated that the iron may include additional metals or other alloying elements. The metal matrix is ​​provided in the form of particles. The particles may have any shape. For example, the particles may be generally spherical. For example, the metal matrix may be iron particles having a median diameter in the range of 80 μm to 120 μm and a narrow particle size distribution. The iron particles of the metal matrix preferably have a rough surface and, therefore, a high specific surface area, as determined, for example, by classification using N2-adsorption according to the Brunauer-Emmett-Teller (BET) adsorption method. For example, the iron particles may have a specific surface area of ​​at least 50 m. 2 / kg, e.g. at least 75m 2 / kg, or at least 100m 2 / kg, for example, a BET specific surface area. 2 It is believed that a specific surface area of ​​100 m / kg provides better contact between the iron particles and other particulate matter in the sintering composition and the connecting surface of the backplate, resulting in better integration of the pre-sintered pack with the protrusions on the connecting surface. This effect is most pronounced when the specific surface area of ​​the iron particles is increased to, for example, 100 m 2 / kg or more, the specific surface area is improved. It is believed that the effect of the large specific surface area provides excellent braking performance even when the sintered composition does not contain copper or nickel. Furthermore, for iron particles with a large specific surface area, the large specific surface area is believed to improve mixing between the iron particles and the lubricant.

[0032] The sintered composition includes a fibrous component. Generally, the fibrous component is a fibrous material that remains fibrous during conductive sintering. Any suitable fibrous material can be used as the fibrous component. Exemplary fibrous components include metal fibers such as steel fibers, brass fibers, bronze fibers, and mineral fibers; ceramic fibers such as silicon carbide fibers or other carbide fibers; silicon oxide fibers, aluminum oxide fibers, or other metal oxide fibers; and mixtures and combinations thereof. The fibrous component can generally be described as a powder. The particles of the fibrous component generally have a rod shape with a length ranging from 50 μm to 500 μm, e.g., from 100 μm to 300 μm, and a thickness and width ranging from 1 μm to 50 μm.

[0033] The sintered composition may contain, for example, 1% to 5% by weight of the friction modifier metal. Any metal with high ductility and / or softness can be used as the friction modifier metal. While mixtures of metals, such as alloys of friction modifier metals, can also be used, it is preferred that the friction modifier metal be free of alloying elements. However, particles of various friction modifier metals may be mixed and added to the sintered composition without alloying them. The inventors believe that, because alloying elements in friction modifier metals reduce ductility, friction modifier metals free of alloying elements have a positive effect on braking performance. Exemplary friction modifier metals are tin, copper, nickel, lead, and mixtures and combinations thereof, although other friction modifier metals are known in the art. However, it is preferred that copper and nickel are not used as friction modifier metals. Furthermore, aluminum is generally not useful as a friction modifier metal. It is preferred that the sintered composition be free of aluminum, i.e., metallic aluminum. A particularly preferred friction modifier metal is tin. The friction modifier metal is preferably used as particles having a size in the range of 50 μm to 200 μm, e.g., 80 μm to 100 μm. Generally, the friction modifier metal particles should be smaller than the iron particles of the metal matrix. This results in better distribution of the friction modifier metal particles among the iron particles of the metal matrix. In particular, it is preferred to use a friction modifier metal having a melting point below the sintering temperature, e.g., tin. When a friction modifier metal having a melting point below the sintering temperature, e.g., tin or lead, is used in the present method, an optimal distribution of the friction modifier metal in the friction material is obtained during the sintering process, improving the braking performance of the friction element. This is not possible when the friction modifier metal does not melt during the sintering process, i.e., when the friction modifier metal is copper or nickel. Without being bound by theory, the inventors believe that, upon melting, the molten friction modifier metal is distributed on the surface of the iron particles of the metal matrix, and therefore iron particles having a large specific surface area, e.g., at least 50 m 2 / kg, especially at least 100m 2It is believed that it is preferable to use iron particles having a BET specific surface area of ​​at least 50 m / kg. It is believed that the distribution of the molten friction-modifying metal on the surface area of ​​the iron particles having a large specific surface area improves the braking performance of the friction material. Therefore, in one example, the iron particles have a large specific surface area, e.g., at least 50 m 2 / kg, especially at least 100m 2 / kg, and the friction-modifying metal, for example tin, has a melting point below the sintering temperature.

[0034] The sintering composition contains a metal phosphide. In this context, a metal phosphide is, for example, a chemical compound of a metal and phosphorus, in which the metal and phosphorus atoms are in ionic form. Therefore, the metal phosphide provided in the sintering composition preferably does not contain phosphorus that is not in the form of a compound with the metal. In the case of iron phosphide, the compound form can be expressed as Fe2P or Fe3P. It is particularly preferred that the iron phosphide is not in the form commonly referred to as ferrophosphorus when used. In one example, the sintering composition does not contain ferrophosphorus. In particular, ferrophosphorus contains unwanted contaminants that adversely affect the control of the manufacturing process. Therefore, if ferrophosphorus is included in the sintering composition, the intended effect of using the metal phosphide cannot be achieved.

[0035] The present inventors have surprisingly discovered that metal phosphides are particularly useful sintering aids in the sintering process used to manufacture friction materials, and that the metal phosphides allow the use of small amounts of friction-modifying metals, i.e., up to 5% by weight, e.g., 0.5% to 1.5% by weight, or 1% to 1.4% by weight, while still providing sufficient braking properties to the resulting friction element. Without being bound by theory, the present inventors believe that upon heating to sintering temperatures, phosphorus atoms from the metal phosphide diffuse into the iron matrix, forming localized regions of phosphorus that are beneficial to the braking properties of the friction element. These localized regions of phosphorus are sometimes referred to as "phosphorus-containing alloys" or "phosphorus-containing mixtures." This effect is particularly pronounced when conductive sintering is employed. Without being bound by theory, the present inventors believe that during conductive sintering, an electric current interacts with the phosphorus in the metal phosphide, further promoting the diffusion of phosphorus atoms, particularly in the form of phosphide. Thus, the effect of the metal phosphide is more pronounced than when heating without current is employed. This effect is believed to be particularly pronounced when the friction-modifying metal melts during sintering, so it is preferred that the friction-modifying metal have a melting point lower than the sintering temperature. Furthermore, it is preferred that a current be applied to raise the temperature to the sintering temperature. However, it is believed that this effect will also be achieved when other friction-modifying metals are used. Thus, the sintering composition includes a metal phosphide in the range of 2.5% to 12% by weight of the sintering composition, e.g., at least 4% and up to 12% by weight, e.g., 5% to 10%, 6% to 9%, or 7% to 8% by weight. The metal phosphide can be an alkaline earth metal phosphide, a transition metal phosphide, a combination or mixture of one or more alkaline earth metal phosphides, a combination or mixture of one or more transition metal phosphides, or a combination or mixture of an alkaline earth metal phosphide and one or more transition metal phosphides. Exemplary metal phosphides are iron phosphide and copper phosphide, particularly phosphides of metals that are present in another form in the sintered composition. The metal phosphide may be present in particulate form in the form of particles having a size ranging from 1 μm to 500 μm, for example from 100 μm to 200 μm.

[0036] The present inventors have surprisingly found that when the friction modifier metal has a melting point below the sintering temperature, and when a current is applied between the sintering cathode and the sintering anode, the distribution of the friction modifier metal is further improved, thereby allowing the friction modifier metal to be used in an amount of 1.5 wt.% or less while still imparting the friction effect of the friction modifier metal to the friction material. Thus, in one example, the friction modifier metal has a melting point below the sintering temperature. For example, the friction modifier metal is tin and is present in the sintered composition in a range of 1 wt.% to 1.4 wt.%. In particular, the friction modifier metal, e.g., tin, can be present as particles having a size in the range of 80 μm to 100 μm. Iron particles can be present in a range of at least 50 μm. 2 / kg, especially at least 100m 2 It is more preferred that the carbon black has a BET specific surface area of ​​1000 .mu.m / kg.

[0037] It is also contemplated that the sintered composition may not require a friction modifier metal. If the sintered composition does not include a friction modifier metal, the contents of the other components are adjusted accordingly. An exemplary sintered composition is shown in Table 2.

[0038] [Table 2]

[0039] Without being bound by theory, the inventors believe that when the metal phosphide is present in a range of, for example, 4% to 12% by weight, such as 5% to 12% by weight or 6% to 12% by weight, friction elements, e.g., brake pads, made without a friction-modifying metal in the method of the present invention can achieve suitable braking properties. This is particularly relevant when the method involves conductive sintering.

[0040] The sintered composition includes a lubricant, particularly a solid lubricant. Any solid lubricant known in the art can be used in the sintered composition. Exemplary solid lubricants are graphite and metal sulfides, such as tungsten disulfide and molybdenum disulfide. Mixtures or combinations of various lubricants are also contemplated. A preferred lubricant is a graphite-based lubricant. Therefore, the sintered composition can include a graphite component. In graphite, carbon atoms are arranged in a hexagonal structure, which is believed to provide the lubricating effect. Graphite is a preferred lubricant. The lubricant is preferably used in the form of particles. For example, the lubricant can be graphite particles having dimensions ranging from 100 μm to 600 μm, e.g., a median diameter ranging from 150 μm to 350 μm. Metal sulfides, such as tungsten disulfide and molybdenum disulfide, are typically smaller than graphite particles. For example, the lubricant may be particles of tungsten disulfide or molybdenum disulfide having a size of less than 100 μm, for example up to 60 μm, for example in the range of 10 μm to 60 μm. The lubricant is present in an amount in the range of 6% to 23% by weight of the sintered composition, for example in the range of 13% to 19% by weight.

[0041] The sintering composition may further include a filler. Any filler known in the art may be used in the sintering composition. Exemplary fillers are non-graphitic carbon, diatomaceous earth, ash, metal fluorides, metal sulfates, and combinations thereof. The filler is typically a particle having a size ranging from 50 μm to 200 μm. The filler may be present in an amount ranging from 1% to 5% by weight of the sintering composition. The non-graphitic carbon component may also be referred to as "coke" or "carbon black."

[0042] The sintering composition includes an abrasive present in an amount ranging from 3% to 20% by weight of the sintering composition, e.g., from 10% to 15% by weight. The abrasive includes particles of metal and / or metalloid oxides, carbides, or nitrides, as well as mixtures and combinations thereof. Thus, for example, the abrasive may include oxides of aluminum, silicon, or zirconium, or silicon carbides, and combinations thereof. However, other abrasives are readily available to those skilled in the art. In particular, abrasives can be classified based on the hardness of the abrasive material. Materials with a certain hardness limit can be considered fillers or abrasives in this context. For example, metal fluorides and metal sulfates can be used in the sintering composition of the present invention. Here, they can be considered fillers or abrasives. Therefore, the total amount of filler and abrasive generally ranges from 6% to 28% by weight. For example, the sintering composition may include an abrasive present in an amount ranging from 6% to 28% by weight. The abrasive is selected from metal oxides, metal carbides, metal fluorides, metal sulfates, and combinations thereof. In one example, the abrasive includes aluminum oxide, e.g., aluminum oxide particles having a size ranging from 10 μm to 30 μm, silicon oxide, e.g., silicon oxide particles having a size ranging from 20 μm to 50 μm and / or 100 μm to 200 μm, and zirconium oxide, e.g., zirconium oxide particles having a size ranging from 50 μm to 150 μm. The oxides can be pure oxides or mixed oxides, e.g., mixed oxides of zirconium and silicon, e.g., mixed oxides in which zirconium oxide constitutes at least 50% by weight of the mixed oxide. For example, the lubricant can be a naturally occurring mineral oxide, e.g., a mineral oxide containing zirconium and silicon as the primary non-oxygen components, optionally including other non-oxygen components, e.g., hafnium, iron, titanium, and other components.

[0043] The powder components of the sintering composition are mixed together, and to aid in mixing, a processing aid, such as a conductive liquid that evaporates during sintering, is added in an amount of 0.2% to 2% by weight, e.g., 0.6% to 1% by weight, based on the dry weight of the sintering composition. When a processing aid is added to the sintering composition, the sintering composition may be referred to as a sintering mix in the context of this disclosure. While any processing aid known in the art can be used, the processing aid is preferably a mineral oil, e.g., a paraffin oil containing an alkane or cycloalkane with a carbon chain length of 8 to 16, particularly an alkane with 10 to 13 carbon atoms. Upon heating, e.g., during the temperature increase to the sintering temperature, or at least at the sintering temperature, the processing aid evaporates from the sintering composition.

[0044] The backplate and friction material each have a thickness, which varies depending on the application of the friction element. For example, the heavier the vehicle on which the brake system is used, the thicker the friction element, particularly the friction material. For example, for a disc brake system for a motorcycle, the thickness of the backplate is typically in the range of 1 mm to 10 mm, e.g., 2 mm to 5 mm. The thickness of the friction material is typically in the range of 1 mm to 15 mm, e.g., 2 mm to 10 mm. Other related vehicles include electric bicycles, e.g., electric mountain bikes or electric cargo bikes, all-terrain vehicles (ATVs), and utility task vehicles (UTVs).

[0045] The friction material has a length between the front end and the rear end of the backplate in the braking direction, and a width defined as a whole by two concentric curves of the annulus when the rotor has an annular shape. When the friction element is used in a motorcycle disc brake system, the length of the friction element is typically in the range of 20 mm to 150 mm, and the width of the friction material is typically in the range of 20 mm to 100 mm.

[0046] The friction material of the friction element is prepared in a sintering process. The material of the backplate can be selected to withstand the temperatures used in the sintering process. Because the sintering process involves applying an electric current to the sintered stack, the backplate should be electrically conductive. The backplate may also be referred to as an electrically conductive backplate. For example, the backplate may be made of a metal, a ceramic material, or a composite material of a metal and a ceramic material. Regardless of the backplate material, the backplate may also have a coating, such as a metal coating. For example, the backplate may be made of an alloy such as steel, stainless steel, brass, or bronze, and may be coated with another metal, such as zinc. A suitable alloy is hot-rolled steel, such as any steel described in European Standard EN10025. Hot-rolled steel may also be referred to as low-carbon manganese steel. The present inventors surprisingly discovered that the electrically conductive sintering process of the present disclosure provides particularly intimate integration of the friction material and the backplate when the backplate is made of hot-rolled structural steel. In particular, closer integration with the backplate is achieved when the voltage is in the range of 0 V to 400 V and the current is in the range of 0 A to 300 A. Without being bound by theory, the inventors believe that the thermal expansion coefficient of the hot rolled structural steel, combined with the electrical conductivity, and the composition of the friction material result in closer integration.

[0047] The backplate has a connecting surface with a plurality of protrusions. The protrusions extend from the connecting surface and form an angle with the connecting surface. The angle is preferably defined in the braking direction of the friction element. The angle can be defined in the range of 20° to 160° from the front end of the backplate. For example, the angle can be in the range of 60° to 120°, such as in the range of 80° to 100°. In one example, the angle is approximately 90°. When the angle is in the range of 60° to 80°, the friction material is more tightly integrated with the backplate than when the angle is outside this range.

[0048] The connecting surface of the backplate comprises a plurality of protrusions. It is preferred that the protrusions are arranged in a plurality of rows in the braking direction, and that the connecting surface comprises a plurality of rows of protrusions in a direction perpendicular to the braking direction. It is particularly preferred that the positions of the protrusions in one row in the braking direction are offset compared to the positions of the protrusions in an adjacent row in the braking direction. Thus, in one example, the connecting surface has a plurality of parallel rows in the braking direction, which are preferably offset. Having offset rows of protrusions on the connecting surface improves integration of the metal matrix and the backplate during the sintering process.

[0049] Overall, each protrusion has a width perpendicular to the braking direction that is in the range of 20% to 100% of the thickness of the friction material. The width in the braking direction may also be in the range of 20% to 100% of the thickness of the friction material. However, in one example, the width in the braking direction is smaller than the width perpendicular to the braking direction.

[0050] The protrusions extend from the connecting surface with a length from the connecting surface. The length of the protrusions is typically in the range of 20% to 100% of the thickness of the friction material, but may be outside this range. When the length of the protrusions is in the range of 50% to 80% of the thickness of the friction material, and the angle of the protrusions is particularly in the range of 60° to 120°, particularly in the range of 80° to 100°, the metal matrix and the back plate are well integrated during the sintering process.

[0051] In one example, the connecting surface has a groove extending from the convex portion in the braking direction. The connecting surface preferably has one groove for each of the plurality of convex portions, particularly one groove for each of the plurality of convex portions. The groove may extend from the convex portion toward the front or rear end of the backplate, for example, in the braking direction or in the direction opposite to the braking direction. Generally, each groove has a depth ranging from 10% to 30% of the thickness of the friction material. Each groove has a length ranging from 50% to 80% of the length of the associated convex portion, as calculated from the associated convex portion. The grooves may have any shape, but in a specific example, the grooves have a triangular shape on the connecting surface. The triangular shape has a wide end adjacent to the associated convex portion and a narrow end facing the front or rear end of the backplate. It is preferred that the connecting surface has a groove for each of the plurality of convex portions, and further that the plurality of convex portions are arranged in staggered rows in the braking direction. In a further example, the connecting surface has a first plurality of rows of convex portions in the braking direction, with grooves extending from each convex portion toward the front end of the backplate, and a second plurality of rows of convex portions in the braking direction, with grooves extending from each convex portion toward the rear end of the backplate, the first plurality of rows and the second plurality of rows alternating in a direction perpendicular to the braking direction.

[0052] If the connecting surface of the backplate has grooves in addition to the protrusions, the iron particles of the metal matrix fill the grooves. Because the sintered composition contains iron phosphide, the electric current in the sintering process more effectively assists in the integration of the metal matrix and the connecting surface. This results in stronger integration of the friction material when the connecting surface has grooves.

[0053] The protrusions on the backplate are preferably made from the same material as the backplate. In one example, the method includes providing a backplate made from a metal or alloy, such as steel, stainless steel, brass, or bronze, and cutting a plurality of grooves into the connecting surface. The cutting process begins at the apex of the connecting surface, and a cutting tool is moved toward the rear or front end of the backplate while cutting the grooves. The grooves are cut from the apex, increasing in width and depth, to the protrusions, where the cutting process stops. This provides triangular grooves in the connecting surface between the apex and the protrusions. The metal of the connecting surface remains attached to the connecting surface at the protrusions. The protrusions are formed at the protrusions by bending the metal, thus forming the protrusions along with the associated grooves. It is preferred to cut a plurality of grooves in the connecting surface in the braking direction. It is also preferred to cut, e.g., simultaneously, a plurality of rows, each having a plurality of grooves, in the braking direction of the backplate. Furthermore, it is preferable to machine the plurality of grooves from the front end to the rear end of the backplate, and to machine the plurality of grooves from the rear end to the front end of the backplate. Thus, the connecting surface can have a first plurality of rows of convex portions in the braking direction, in which a groove extends from each convex portion toward the front end of the backplate, and a second plurality of rows of convex portions in the braking direction, in which a groove extends from each convex portion toward the rear end of the backplate. The first plurality of rows and the second plurality of rows alternate in a direction perpendicular to the braking direction.

[0054] The protrusions thus formed preferably have an angle ranging from 60° to 120°, for example, from 80° to 100°. Each protrusion may have a different shape. For example, the protrusions may be straight, curved, or hook-shaped. Furthermore, the grooves, and particularly the protrusions, are roughened by the cutting process. The inventors surprisingly discovered that the roughened surfaces and various shapes of the protrusions and grooves result in a more intimate interaction between the metal matrix and the connecting surface during the sintering process. This is even more pronounced when the connecting surface has multiple offset grooves formed by the cutting process, as described above. Without being bound by theory, the inventors believe that the roughened surface allows for better contact between the metal matrix and the backplate material, resulting in better integration between the friction material and the connecting surface. This effect is even more pronounced when the sintering composition contains iron phosphide and an electric current is applied during sintering.

[0055] The sintering mixture is applied to the connecting surface of the backplate, and the sintering mixture is molded to form an intermediate friction element having a pre-sintered pack on the backplate. The molding is performed by applying a pressure of 300 kg / cm to the sintering mixture on the backplate. 2 ~3300kg / cm 2 The sintering step may be carried out by applying a pressure in the range of 29 MPa to 324 MPa, or in the range of 294 bar to 3236 bar. The pressure is typically maintained for a molding time of at least 10 seconds, for example, a molding time of 10 seconds to 10 minutes. If the sintering composition includes a friction modifier metal having a melting point below the sintering temperature, it is preferred that the temperature in the molding step be below the melting point of the friction modifier metal.

[0056] Furthermore, conductive sintering is preferably performed in a chamber, furnace, or the like where the atmosphere can be controlled. Conductive sintering can be performed at a pressure lower than atmospheric pressure, e.g., in a vacuum, and / or the atmosphere composition can be controlled, e.g., to an oxidatively inert atmosphere, e.g., an atmosphere of H2 in N2, 5 vol% H2, 95 vol% N2, etc.

[0057] Any embodiment of the present disclosure may be used in any aspect of the present disclosure, and advantages for a particular embodiment apply equally when the embodiment is used in a particular aspect.

[0058] In the following, the disclosure will be explained in more detail with the aid of examples and with reference to schematic drawings. [Brief explanation of the drawings]

[0059] [Figure 1] FIG. 1 shows a friction element of the present disclosure. [Figure 2] FIG. 2 shows a photograph of a motorcycle wheel equipped with a brake having a friction element of the present disclosure. [Figure 3] FIG. 3 shows a backplate for manufacturing the friction element of the present disclosure. [Figure 4] FIG. 4 shows an intermediate friction element of the present disclosure. [Figure 5] FIG. 5 shows a sintered stack of the present disclosure. [Figure 6] FIG. 6 shows the temperature profile of an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0060] The present disclosure is not limited to the embodiment or embodiments shown in the drawings, and therefore, although reference signs may be used after features recited in the appended claims, it will be understood that such signs are included solely for ease of understanding of the claims and in no way limit the scope of the claims.

[0061] This disclosure relates to a method of manufacturing a friction element 1, shown in FIG. 1. The friction element 1 includes a back plate 2 and a friction material 11. FIG. 2 shows a photograph of a motorcycle wheel 3 equipped with a brake assembly 32 having the friction element 1. Accordingly, FIG. 2 shows the wheel 3 with the tire 31 and the brake assembly 32. The friction element 1, not visible in FIG. 2, is disposed in the brake assembly 32. When the rotor 33 rotates, the friction element 11 of the brake assembly 32 presses against the rotor 33, creating friction and stopping the rotor rotation. The friction element 1 and back plate 2 have a front end 12 and a rear end 13 that are defined by the direction of rotation of the rotor 33 in which the friction material 11 is used.

[0062] Friction element 1 can be tested using any standard test. For example, friction element 1 can be subjected to a shear test according to ISO 6312 or a compressibility test according to ISO 6310. ISO 6312 generally analyzes the bond strength between the lining material and the carrier in a disc brake pad assembly or drum brake shoe assembly. ISO 6310 generally analyzes the compressive displacement of a brake lining or brake pad assembly due to load and temperature, as well as the thermal expansion or growth of the lining. Brake pads, such as friction element 1, can also be analyzed using dynamometer testing. For example, the SAE J2522 test (defined by the Society of Automotive Engineers, SAE International) evaluates the effectiveness behavior of friction materials with respect to pressure, temperature, and speed in vehicles equipped with hydraulic brake actuators. The primary purpose of SAE J2522 is to enable comparison of brake pads tested by comparing friction materials under identical conditions.

[0063] Example 1 A sintered composition was prepared by mixing friction modifier metal powder, fiber component powder, metal phosphide powder, lubricant powder, filler powder, abrasive powder, processing aids, and the balance iron powder. Specifically, the sintered composition contained 58 wt% iron powder, and the friction metal was tin present at 1.2 wt%. The iron powder had a median particle size of approximately 90 μm. The specific surface area, determined using N2-adsorption according to the Brunauer-Emmett-Teller (BET) adsorption method, was approximately 75 m 2 / kg. The tin was obtained as particles with a median diameter of about 80 μm. The tin particles were generally non-porous. The mixture contained about 5 wt. % iron phosphide.

[0064] Graphite particles having a median diameter of about 200 μm were added as a lubricant in an amount of about 15 wt %.

[0065] Mineral zircon particles having a median diameter of about 100 μm were used as the abrasive at about 12 wt %.

[0066] Diatomaceous earth was provided and applied as a filler at 3 wt % without further modification.

[0067] Steel fibers with an average length of about 200 μm and a width of about 25 μm were added at about 5% by weight.

[0068] The powdered ingredients were mixed before adding 1 wt% paraffin oil as a processing aid, and the paraffin oil-containing ingredients were mixed thoroughly.

[0069] As shown in Figure 3, a backplate 2 made from hot-rolled low-carbon manganese steel was provided. The backplate 2 had a thickness of approximately 4 mm and dimensions of 4 cm x 4 cm, and included a mounting ring 14. The backplate 2 defined the front end 12 and rear end 13 of the friction element 1 that would ultimately be produced in this method. See also Figure 1.

[0070] The connecting surface 21 was provided by a protrusion 22. The protrusion 22 was obtained by cutting a groove 23 into the connecting surface 21. As a result, the connecting surface 21 had a groove 23 with an overall triangular shape. The triangular shape had a wider end adjacent to the associated protrusion 22 and a narrower end facing the front end 12 or rear end 13 of the backplate 2. The protrusion 22 extended from the connecting surface 21 at approximately a right angle.

[0071] The sintering composition is applied to the connection surface in a layer about 4 mm thick, and the backplate 2 together with the sintering composition is applied in a vice and subjected to a pressure of about 2000 kg / cm 2 and pressurized for a molding time of about 2 minutes to form the intermediate friction element 4 having a pre-sintered pack 41 as shown in FIG.

[0072] The intermediate friction elements 4 were applied to a sintering stack 100. A schematic diagram of the sintering stack 100 is shown in FIG. 5 with a plurality of intermediate friction elements 4. FIG. 5 is not drawn to scale. Specifically, four rows, each having six intermediate friction elements 4, were applied to a sintering anode 51 made of carbon fiber reinforced carbon (CFC) as the conductive material 101, and a further layer of conductive material 101 made of CFC. Another further layer of intermediate friction elements 4 was then applied to the conductive material 101. The conductive material 101 had a thickness of about 3 cm. The sintering stack 100 included a total of ten layers of intermediate friction elements 4 separated by layers of CFC as the conductive material 101. The pressure between the sintering anode 51 and the sintering cathode 52, and therefore the pressure on the intermediate friction elements 4, was 100 kg / cm. 2 was set to.

[0073] The sintering anode 51 and the sintering cathode 52 were electrically connected to a power supply 102. In FIG. 5, the power supply 102 is shown with + and -, but the power supply 102 may provide direct current, pulsed direct current, or alternating current. The sintering stack 100 included three thermocouples 103. While FIG. 5 shows two thermocouples 103, it should be understood that any number of thermocouples 103 may be used in a particular sintering stack 100. Specifically, the central conductive material 101 in the sintering stack 100 included a thermocouple 103, and two additional thermocouples were used near the sintering anode 51 and the sintering cathode 52, respectively. The thermocouples 103 were electrically connected to the power supply 102 and a data processing unit (not shown) to define a feedback loop for controlling the power of the power supply 102 from the temperature recorded from the thermocouples 103.

[0074] The sintered stack was housed in a cabinet with a gas inlet and outlet for controlling the cabinet atmosphere. The cabinet, gas inlet, and gas outlet are not shown in Figure 5. After applying pressure to the sintered stack, the atmosphere in the cabinet was replaced with an oxidizing inert atmosphere consisting of 5 wt% H2 and 95 wt% N2.

[0075] The sintering temperature was set to 835°C, and the temperature of the sintering stack 100 was increased by applying an alternating current from the power supply 102. The alternating current had a frequency of approximately 50 Hz, and the current was controllable with a voltage of approximately 380 V. The temperature profile was monitored using a thermocouple 103, as shown in Figure 6. Figure 6 shows the recorded temperature and set temperature on the Y axis, and the number of log points for the process on the X axis. The temperature was recorded every 40 seconds. Each temperature measurement represents a log point in Figure 6. Specifically, the temperature was increased to 230°C, near the melting point of tin, and held at 230°C for approximately 5 minutes. After that, the temperature was increased to the sintering temperature of 835°C. After maintaining the sintering temperature for approximately 1.5 hours, the sintering stack 100 was cooled. No active cooling was performed, but the power supply 102 was set to a temperature of 150°C to gradually cool the sintering stack 100. Thus, FIG. 6 shows the set temperature "TempSet" and the temperatures "Temp1," "Temp2," and "Temp3" measured by the three thermocouples 103. Temp1 is the temperature recorded by the thermocouple 103 of the central conductive material 101, and Temp2 and Temp3 are the temperatures recorded by the other thermocouples 103. FIG. 6 also shows the upper limit temperature "UTLTemp" and the lower limit temperature "LTLTemp." The upper limit temperature and the lower limit temperature were set in the process to indicate temperature values ​​that the process temperature should not deviate from during the heating and maintaining steps at the sintering temperature. As is clear from FIG. 6, Temp1, Temp2, and Temp3 were all near the set temperature TempSet during the heating and maintaining steps. Notably, the recorded temperatures barely deviated from the set temperature. While the measured temperatures deviated from the set temperature profile during the cooling of the sintering stack 100, this deviation did not affect the results of the manufacturing method.

[0076] Example 2 The friction elements prepared in Example 1 were installed in the brakes of a KTM 1290 Super Duke GT and a Honda CBR650FA motorcycle, and subjective evaluations of the friction elements of the present disclosure were compared to brakes equipped with commercially available brake pads known as SBS-SI-90HH(HS) obtained from SBS Friction A / S, Svendborg, Denmark. The subjective evaluations are summarized in Table 3, where "KTM" refers to the KTM 1290 Super Duke GT and "Honda" refers to the Honda CBR650FA motorcycle. Also, "HS" refers to the SBS-SI-90HH(HS) brake pads, and "Ex. 1" refers to the friction element prepared in Example 1. The friction elements were rated within a parameter range and given a subjective score ranging from 1 to 5, with 5 being the best score.

[0077] [Table 3]

[0078] As is clear from Table 3, the friction element of Example 1 outperformed the commercially available brake pads on both bikes.

[0079] 1 Friction element 11 Friction materials 12 Front end 13 Rear end 14 Mounting ring 2 backplate 21 Connection surface 22 Convex part 23 Groove 3 wheels 31 Tires 32 Brake Assembly 33 Rotor 4 Intermediate friction elements 41 Pre-sintered packs 51 Sintered anode 52 Sintered cathode 100 sinter stacks 101 Plate made of conductive material 102 Power supply 103 Thermocouple

Claims

1. - providing a backplate (2), said backplate (2) having a connection surface (21) with a plurality of protrusions (22); - providing a sintering composition, said sintering composition comprising: 0% to 5% by weight of a friction modifier metal; a fiber component in the range of 1% to 10% by weight; metal phosphide in the range of 2.5 wt.% to 12 wt.%; a lubricant in the range of 6% to 23% by weight; a filler in the range of 0% to 5% by weight; an abrasive in the range of 3% to 20% by weight; Processing aids in the range of 0.2% to 2% by weight; The remaining iron, and - applying said sintering composition to said connecting surface (21) and molding said sintering composition to form an intermediate friction element (4) with a pre-sintered pack (41) on said backplate (2); - placing one or more intermediate friction elements (4) between a sintered carrier (51) and a sintering vise plate (52) with the backplate (2) facing the sintered carrier (51) and the pre-sintered pack (41) facing the sintering vise plate (52) or with the backplate (2) facing the sintering vise plate (52) and the pre-sintered pack (41) facing the sintered carrier (51); - carrying out the following steps simultaneously, which steps are: >10 kg / cm ２ ~200 kg / cm ２ applying a pressure in the range of between the sintering vise plate (52) and the sintering carrier (51); > increasing the temperature between the sintering vise plate (52) and the sintering carrier (51) to a sintering temperature in the range of 800°C to 950°C; and maintaining at least one of the applied pressure and the sintering temperature for a sintering time ranging from 1 hour to 10 hours to form a friction material on the backplate (2); A method for manufacturing a friction element (1) comprising:

2. The sintered carrier (51) is a sintered anode (51), The sintering vise plate (52) is a sintering cathode (52), applying an electric current between the sintering cathode (52) and the sintering anode (51) to raise the temperature to the sintering temperature; maintaining at least one of the applied current, the applied pressure, and the sintering temperature for the sintering time; A method for manufacturing a friction element (1) according to claim 1.

3. Raising the temperature to the sintering temperature without external heating; A method for manufacturing a friction element (1) according to claim 2.

4. the friction-modifying metal has a melting point below the sintering temperature; A method for manufacturing a friction element (1) according to claim 1.

5. the friction modifier metal is present in the range of 1% to 1.5% by weight of the sintered composition; A method for manufacturing a friction element (1) according to claim 1.

6. the sintered composition comprising metal phosphide in the range of 4 wt% to 12 wt%; A method for manufacturing a friction element (1) according to claim 1.

7. The sintered composition is a fiber component in the range of 1% to 10% by weight; metal phosphide in the range of 2.5 wt.% to 12 wt.%; a lubricant in the range of 6% to 23% by weight; a filler in the range of 0% to 5% by weight; an abrasive in the range of 3% to 20% by weight; Processing aids in the range of 0.2% to 2% by weight; The remaining iron, Equipped with A method for manufacturing a friction element (1) according to claim 1.

8. The step of molding the sintered composition to form an intermediate friction element (4) comprises applying a pressure of 300 kg / cm to the sintered composition on the back plate (2). ２ ~3300kg / cm ２ applying a pressure in the range of A method for manufacturing a friction element (1) according to claim 1.

9. The molding has a molding time ranging from 10 seconds to 10 minutes. A method for manufacturing a friction element (1) according to claim 8.

10. The protrusion (22) extends from the connecting surface (21) with a length in the range of 50% to 80% of the thickness of the friction material; The convex portion (22) is inclined on the connecting surface (21) at an angle in the range of 60° to 120°. A method for manufacturing a friction element (1) according to claim 1.

11. A plurality of intermediate friction elements (4) are arranged in two or more layers of the sintered stack, each layer being separated by a plate (101) made of a conductive material; A method for manufacturing a friction element (1) according to any one of claims 2 to 10.

12. the current is an alternating current having a voltage in the range of 0 to 400 V and a current in the range of 0 A to 300 A; A method for manufacturing a friction element (1) according to any one of claims 2 to 10.

Images