Method for manufacturing a friction material, in particular a method for manufacturing brake pads and associated brake linings

Abstract

A method for producing a friction material, the method successively comprising the following steps: mixing an aluminosilicate source with an alkaline silicate solution to form a geopolymer; adding a friction mixture to the geopolymer solution of the previous step to obtain a slurry; casting the slurry in a mold at a temperature between room temperature and 120 °C for 5 minutes to 2 hours; and demolding to obtain a sheet; attaching a backing plate to the sheet; curing at a temperature between X and Y for a time between X hours and Y hours. The friction material obtained by the method is used for manufacturing a friction layer / block and / or a friction disc for a friction element, such as a braking element, including a vehicle brake pad or block.

Description

[0001] Cross - reference to related applications

[0002] This patent application claims the priority of Italian Patent Application No. 102020000001012, filed on January 20, 2020, the entire disclosure of which is incorporated herein by reference. Technical field

[0003] The present disclosure generally relates to methods for producing friction materials, and more particularly to methods for manufacturing friction blocks and associated brake pads.

[0004] Embodiments of the present disclosure illustrate more efficient methods for producing friction materials for friction elements, such as brake elements, e.g., vehicle brake pads or brake blocks, and more effective methods for the preparation of associated friction materials and corresponding inorganic binders, which contribute to obtaining friction materials and associated brake pads that resist the heat generated during braking while providing optimal braking performance and optimal tribological properties. Background art

[0005] EP3128201 discloses a method for obtaining an adhesive for brake pads. The use of geopolymers replaces the traditional process using phenolic resins. However, there may be certain drawbacks associated with the dry grinding process described in EP3128201.

[0006] GB2357517 discloses a friction material comprising a continuous phase, which is a reaction product obtained by reacting an alkali metal hydroxide, the metal being from Group 1 of the periodic table, and / or an alkali metal silicate, with a reactive comminuted material comprising silica, silicate, and / or aluminate.

[0007] For example, during grinding (performed in air) and when opening the grinder and unloading the product, baking soda may absorb a large amount of moisture from the environment.

[0008] When subsequently mixed with kaolin and other fillers added to the friction material compound, the soda will retain some of this residual moisture and be released in the form of vapor during the hot molding of the brake pad, which may cause some spalling and cracking in the finished friction material.

[0009] However, embodiments of the friction materials in the present disclosure can be used to manufacture friction layers / blocks and / or asbestos - free friction discs for friction elements, such as brake elements, i.e., vehicle brake pads or brake blocks, where the performance is similar to or better than that of friction materials belonging to the NAO (“non - asbestos organic friction material”), “low - steel” and “semi - metal” categories, while avoiding some of the drawbacks disclosed above. Summary of the invention

[0010] Thus, the present disclosure generally relates to a method for producing a friction material for use in friction elements, such as brake elements, e.g., vehicle brake pads or brake blocks, as defined in one aspect of the present invention.

[0011] The present disclosure also generally relates to associated binders and friction elements, specifically brake pads or brake blocks, presenting friction layers or blocks produced by the method of the present disclosure.

[0012] According to the present disclosure, such an object is achieved by a method for producing a friction material according to one aspect of the present invention and a method for producing a brake pad according to another aspect of the present invention.

[0013] According to the present disclosure, a method for producing a friction material comprises the following steps, preferably carried out in sequence:

[0014] a) Mixing a source of aluminosilicate with an alkaline silicate solution to form a geopolymer solution, where any geopolymer has not yet fully formed;

[0015] b) Adding a friction mixture to the geopolymer solution of the previous mixing step to obtain a slurry;

[0016] c) Casting the slurry in a mold at a temperature between room temperature and 120 °C and maintaining the slurry inside the mold for a time period including between 5 minutes and 2 hours, in any case until the slurry has substantially solidified; and

[0017] d) Demolding the solidified slurry to obtain a solid friction material sheet or block.

[0018] In some embodiments of the method disclosed herein, the mixing step may be carried out such that at its end, a slurry having a pseudoplastic behavior and consisting of the above-mentioned geopolymer solution is obtained. For a pseudoplastic solution, a shear-thinning fluid, the viscosity of such fluids will decrease as the shear rate increases.

[0019] In some embodiments, a friction mixture is added to the geopolymer solution to obtain a slurry having pseudoplastic properties (e.g., a mixture comprising particulate solids suspended in water and / or another liquid).

[0020] In some embodiments, the SiO 2 / Al 2 O 3 molar ratio in the slurry is preferably between 3 and 5.

[0021] SiO 2 / R 2The O ratio is preferably between 0.7 and 1.5, and R can be selected from Na, K, Li, Ce, Ru.

[0022] Preferably, H 2 O / Al 2 O 3 The molar ratio is between 10 and 25.

[0023] The present disclosure generally also relates to embodiments of a method for manufacturing a braking element, specifically a brake pad, the method comprising performing the above-described method for producing a friction material and additional steps: e) attaching a backing plate to the solid friction material sheet or block as a result of the casting step or after the solid friction material sheet or block has been demolded.

[0024] The method for manufacturing a braking element, specifically a brake pad, comprises additional steps: f) curing the solid friction material sheet or block having the backing plate attached thereto at a temperature between 60 and 120 °C for a time between 1 hour and 24 days. Description of the Drawings

[0025] Preferred but non-limiting embodiments will now be described in more detail with reference to a number of actual working examples of their implementation and with reference to the accompanying drawings, which are only intended to disclose, in a non-exhaustive and non-limiting manner, features that are part of the present disclosure, in which:

[0026] Figure 1 is a flow chart depicting a method of manufacturing a friction material according to an embodiment described herein.

[0027] Figure 2 Shows an example of a brake pad comprising the produced friction material according to an embodiment described herein.

[0028] Figure 3 is a graph showing the results of a comparative braking efficiency test according to the AKM standard: the same brake pads produced with a prior art formulation of a friction material comprising a phenolic resin according to the formulation reported in Comparative Example 1; and brake pads obtained with the formulation of Comparative Example 2 by the method of EP3128201; and brake pads obtained with the formulation of Example 3 by the method of the present disclosure. Detailed Description

[0029] In the following detailed description, reference is made to the accompanying drawings which form a part hereof. In the drawings, like reference numerals generally identify like components unless the context otherwise indicates. The illustrative embodiments described in the detailed description and the drawings are not intended to be limiting. Other embodiments may be used and other changes may be made without departing from the spirit or scope of the subject matter presented herein.

[0030] In a preferred embodiment, the first step of the present disclosure process consists of: mixing together the components suitable for making a geopolymer that can be used as an inorganic binder to form a fluid geopolymer, i.e., a geopolymer mixture in fluid form since it has not yet polymerized.

[0031] Figure 1 is a flowchart depicting a method 100 of manufacturing a friction material according to an embodiment described herein. Figure 2 An example of a brake pad 200 is shown that includes a friction material block 202 (also referred to herein as a "sheet") attached to a backing plate 204. The friction material block 204 can be produced according to any of the embodiments described herein, including with respect to Figure 1 the method 100 described.

[0032] Specifically, method 100 includes mixing an aluminosilicate source with an alkaline silicate solution at step 102.

[0033] As the aluminosilicate source, metakaolin is preferably used. However, in addition to or in place of metakaolin, other sources of aluminosilicate such as kaolin or fly ash or bottom ash or combinations thereof can also be used. Additionally, a silica source such as quartz, or colloidal silica dissolved in an alkaline sodium hydroxide solution or potassium hydroxide solution, can also be considered an aluminosilicate source under suitable conditions.

[0034] Preferably, the aluminosilicate source is selected from the group consisting of: metakaolin, kaolin, or fly ash or bottom ash.

[0035] As just one example, metakaolin can be obtained by high-temperature calcination of kaolin from "Imerys Refractory Minerals - Argical - M1000S". This metakaolin contains approximately 55% SiO 2 and 39% Al 2 O 3 , plus Fe 2 O 3 , TiO 2 , K 2 O, Na 2 O, Cao and MgO impurities, and generally is assumed to have the following chemical general formula:

[0036] Al 2 O 3 ·2SiO 2

[0037] The alkaline silicate solution is preferably selected from the group consisting of: sodium silicate and sodium hydroxide systems, potassium hydroxide and potassium silicate systems, lithium hydroxide and lithium silicate systems.

[0038] Preferably, a sodium silicate and sodium hydroxide system is used. The potassium hydroxide and potassium silicate system can also be used as an alternative or in combination with sodium and / or potassium, and similarly, other alkali metals on which geopolymers can be developed, namely lithium, cesium, and rubidium, can also be used as alternatives or in combination with sodium and / or potassium. The sodium-based system will be mainly mentioned hereinafter.

[0039] Only as an example, potassium silicate (or sodium silicate) from the company "Ingessil srl" can be used with the addition of a small amount of potassium hydroxide (or sodium hydroxide). In some other embodiments, hydroxides are not included.

[0040] Preferably, a stirrer, preferably a mechanical stirrer, is used to mix the aluminosilicate source with the alkaline silicate solution. The speed of the stirrer can vary with the viscosity of the mixture. Preferably, the speed is between 200 and 1000 rpm, more preferably between 500 and 1000 rpm. The stirring time can also vary according to the desired mixture and can vary between 5 minutes and 30 minutes. Only as an example, the stirring time can be 10 minutes.

[0041] At step 104 of the process, method 100 may include adding the friction mixture to the previously mentioned components of the geopolymer, which are still in solution to obtain a slurry composed of the friction material in fluid form; specifically, preferably, a pseudoplastic slurry, i.e., a non-Newtonian fluid, is obtained.

[0042] One or more fluid geopolymers (i.e., still not polymerized) with different compositions can be used in combination with the friction mixture.

[0043] Preferably, the friction mixture includes:

[0044] - Fibers, preferably inorganic fibers and / or organic fibers and / or metal fibers;

[0045] - At least one inorganic or metallic filler or abrasive; and

[0046] - At least one friction modifier and / or lubricant, for example, comprising sulfur and / or carbon materials or nanomaterials.

[0047] According to various embodiments, the methods described herein perform the following:

[0048] - Replace the current organic binder with an inorganic binder as disclosed above;

[0049] - Reduce the content of abrasives;

[0050] - Increase the content of the lubricant.

[0051] In some embodiments, the friction material obtainable according to the present disclosure is also preferably free of copper and / or its alloys, whether in powder form or in fiber form.

[0052] Advantageously, the fibers comprise at least one of organic fibers, inorganic fibers or metallic fibers other than asbestos.

[0053] Illustrative examples include: inorganic fibers such as glass fibers, wool or rock fibers, wollastonite, sepiolite and attapulgite; and organic fibers such as aramid fibers, polyimide fibers, polyamide fibers, phenolic fibers, cellulose and acrylic fibers or PAN (polyacrylonitrile), carbon fibers (nanotubes or another carbon-based fiber); metallic fibers such as steel fibers, stainless steel, aluminum fibers, zinc, etc.

[0054] The fibers can be used in the form of short fibers.

[0055] In some embodiments, the amount of fibers is preferably between 2 vol% and 30 vol% of the total volume of the friction material, and more preferably between 8 vol% and 15 vol%. In some embodiments, the fiber component comprises rock fibers, which have been shown to have a strong affinity for geopolymers used as binders.

[0056] As the organic filler or inorganic filler, different materials can be used. Preferably, the filler can be selected from the group consisting of: calcium carbonate, barium sulfate, magnesium oxide, calcium hydroxide, calcium fluoride, slaked lime, talc, mica and combinations thereof.

[0057] Based on the total composition of the friction material, the amount of the filler is preferably between 2 vol% and 40 vol%.

[0058] The friction modifier can comprise all or part of the filler.

[0059] The friction modifier preferably includes at least one material from the following group:

[0060] - Carbon materials;

[0061] - Graphite;

[0062] - Organic fillers such as cashew nut powder, rubber powder, powdered tread rubber, unvulcanized rubber particles, vulcanized rubber particles;

[0063] - Inorganic fillers such as barium sulfate, calcium carbonate, calcium hydroxide, vermiculite and / or mica;

[0064] - Abrasives such as silicon carbide, alumina, zirconium silicate;

[0065] - Metal sulfide-based lubricants such as molybdenum disulfide, tin sulfide, zinc sulfide, iron and colored sulfides, metal particles other than copper and copper alloys;

[0066] and / or combinations of the foregoing.

[0067] Abrasives can be classified as follows (the following list is for reference only, not necessarily exhaustive and not restrictive):

[0068] · Mild abrasives (Mohs 1-3): talc, calcium hydroxide, potassium titanate, mica, kaolin, vermiculite;

[0069] · Medium abrasives (Mohs 4-6): barium sulfate, magnesium oxide, calcium fluoride, calcium carbonate, wollastonite, calcium silicate, iron oxide, silicon dioxide, chromite, zinc oxide;

[0070] · Strong abrasives (Mohs 7-9): silicon carbide, zircon sand (zirconia), zirconium silicate, zircon, corundum, alumina, mullite.

[0071] Preferably but not necessarily, the friction material does not contain strong abrasives and only contains medium abrasives or mild abrasives.

[0072] When mixed with a conventional friction mixture, the above-prepared geopolymer slurry can actually be considered a medium abrasive in itself.

[0073] The total content of the friction modifier can vary according to the desired friction characteristics and is preferably between 2 vol% and 40 vol% of the total volume of the friction material, preferably between 4 vol% and 30 vol%.

[0074] The volume ratio of the friction modifier to the abrasive contained in the friction material to be formed is preferably selected between 1:2 and 1:5. In contrast, in known friction materials with organic binders, this ratio is usually 1:8 or higher.

[0075] It should be noted that when the geopolymer is fully polymerized to reach a solid form, the main abrasive work of the friction material of the present disclosure is completed by the geopolymer matrix of the sheet.

[0076] Herein, "binder consisting almost entirely of geopolymer" means that the geopolymer or geopolymer compound constitutes at least 30 wt% - 90 wt% of the total amount of the binder present in the friction element, more preferably more than 40 vol% of the binder.

[0077] Based on the total volume calculation of the composite, the binder preferably exists in the composite of the friction material in the form of a slurry in an amount equal to or greater than 30% by volume or even more preferably greater than 50% by volume. In fact, experiments have shown that when the amount of the inorganic binder is too small, depending on the type of the binder and the nature of other materials used in the composite, the mechanical properties required for its use as a friction material cannot be achieved.

[0078] The friction material according to the method of the present disclosure can be almost completely or completely lacking in an organic binder (which can be present in an amount of at most equal to or less than 10% by weight), and thus will not undergo thermal degradation due to oxidation at high temperatures above 300 °C and up to over 600 °C.

[0079] The binder is produced according to the method of the present disclosure and is used as the single and main binder in the friction material according to the present disclosure, and thus generally, as mentioned above, the binder is obtained by a chemical reaction starting from inorganic precursors such as SiO 2 and Al 2 O 3 and the like.

[0080] The step 104 of mixing the components of the geopolymer and the friction mixture is obtained by stirring for a time variable preferably from 5 minutes to 30 minutes. Such time can vary according to the composition of the obtained slurry.

[0081] As already mentioned, the slurry obtained by mixing the components of the geopolymer and the friction mixture is preferably stirred at a speed of 200 to 1000 rpm. The speed can vary according to the rheology of the mixture.

[0082] After step 104, the method can further include a step 106 of casting and solidifying the friction material slurry and a step 108 of demolding.

[0083] Specifically, the slurry can be cast in a solidified mold at step 106, and a solid friction material sheet or block (such as the friction material block 202 shown Figure 2 ) can be extracted from the mold during demolding at step 108. In some embodiments, more preferably, the temperature is set to be between room temperature and 120 °C. In some embodiments, the temperature is between 60 °C and 90 °C. In some embodiments, the temperature is 80 °C.

[0084] Preferably, the sheet is removed from the mold after a time between 5 minutes and 2 hours, more preferably between 10 minutes and 30 minutes.

[0085] Time and temperature can vary with reactivity. During molding, the geopolymer particles consolidate and remain amorphous, resulting in a friction element, typically a brake pad, in which the component materials are dispersed into a matrix consisting solely or substantially solely of an amorphous geopolymeric inorganic binder.

[0086] The method 200 may further include a subsequent step 110 of attaching the sheet to a backing plate (e.g., by gluing to a backing plate such as Figure 2 the backing plate 204 etc.) or, the backing plate may be disposed inside the mold before the casting step 106 such that a complete brake pad can be obtained directly after the demolding step 108.

[0087] Thereafter, the sheet provided with the backing plate is subjected to a curing step 112.

[0088] Depending on the geopolymer composition, the curing step 112 preferably lasts between 1 hour and 48 hours, preferably between 2 hours and 12 hours, more preferably 12 hours.

[0089] The temperature of the curing step 112 can vary according to the composition, but preferably includes between 60 °C and 120 °C, more preferably between 60 °C and 100 °C, more preferably 80 °C.

[0090] The starting materials used to obtain the geopolymer binder are selected such that the SiO 2 / Al 2 O 3 molar ratio of the inorganic geopolymer binder in the friction material according to the present disclosure is between 3 and 5, and the SiO 2 / R 2 O molar ratio is between 0.7 and 1.5. Preferably, the H 2 O / Al 2 O 3 molar quantification is between 10 and 25.

[0091] The density of the geopolymer powder is obtained during the casting step 106.

[0092] The obtained brake pads can be used for disc brake pads, brake shoes and linings of vehicles such as cars, trucks, train carriages and various other types of vehicles and industrial machines, or for applications of clutch discs.

[0093] The result is that the performance of the brake pads is comparable to that of the brake pads obtained by the process of EP3128201, resulting in its braking performance and disc wear being comparable to those of the friction material produced by the hydrothermal synthesis according to EP3128201.

[0094] The advantage of the new process for manufacturing brake pads is that material consolidation is achieved at least in a low-pressure system compared to traditional phenolic resin systems that require high pressure.

[0095] In addition, compared to traditional phenolic resin systems that require a relatively high temperature (above 200 °C), the curing step 112 is carried out at a low temperature (below 120 °C) to achieve maximum physical properties.

[0096] The system is more sustainable as it saves more energy and emits less during the production of the pads.

[0097] The new process allows for the adjustment of the viscosity of the mixture in order to use different shaping techniques (casting, extrusion), and it is possible to vary the water content or add some rheological modifiers such as clay or superplasticizers.

[0098] In addition, molding can be carried out without any pressure, and the heat treatment is fast and at a lower temperature than the treatment temperature of known brake pads.

[0099] Finally, compared to traditional processes, less space is required on the production line and thus higher productivity is possible.

[0100] The examples and comparative examples reported herein are for illustrative purposes and are not intended to limit the present disclosure.

[0101] Comparative Example 1

[0102] To compare the performance of known brake pads including friction materials obtained by known methods and including organic binders and specifically phenolic resins, two identical friction material formulations were prepared, using the average values at intervals reported in Table 1 for each component, as follows:

[0103] Table 1

[0104]

[0105]

[0106] Comparative Example 2

[0107] Using a drill stirrer and a specific mixing agitator for medium to high viscosity fluids, 115.7 grams of metakaolin from "Imerys Refractory Minerals" was mixed with 300.0 grams of 139.4g sodium silicate in any form (as indicated, potassium silicate is also feasible) and 1.51g of agglomerated caustic soda aqueous solution, in this case, the aqueous solution from "PQ Corporation - Holland", at a speed of 800 rpm for a time between 5' and 45'. The wet paste obtained by mixing the metakaolin with the sodium silicate - caustic soda solution was spread and dried using Mylar sheets, specifically using the following parameters for the wet and alkaline paste / mortar: the thickness of the spread paste is between 0.1 and 3 mm, the drying temperature is between 40°C and 250°C, the sheet size is between A3 and A4, and the drying time varies between 10' and 90'.

[0108] Then the dried binder in the form of solid aggregates was separated from the sheet and ground in a ball mill at a speed of 275 revolutions per minute for 14 hours to granulate the product to at least 150 microns.

[0109] The final product is a powder to be used as a binder.

[0110] The granular characteristics of the resulting powdered binder are shown in Table 2 below.

[0111] Table 2

[0112] Sample d10 d50 d90 #24-1 8 66 295

[0113] The particle size determination of the ground product is between 7.0 microns and 300 microns, with at least 50% of the product having a particle size determination of approximately 50 - 70 microns.

[0114] Two identical friction material formulations were prepared, using the average values at intervals reported in Table 3 below for each component, and using the powder obtained from Example 1 as the binder, designated as "binder mixture".

[0115] Table 3

[0116]

[0117]

[0118] The binder mixture was added to the other components of the mixture according to a general protocol: 20 - 60 wt% binder, 40 - 80 wt% other components; the mixing was completed using a Loedige mixer.

[0119] Subsequently, apart from the fact that the binder according to EP3128201 was used, two mixtures with the same quantity and composition were obtained and used to mold two series of identical brake pads, placing the raw or "green" compound and the metal support in a mold in each case. The molding was carried out in steps at a temperature of 100 - 150 / 70 - 135 / 70 - 135 °C, so that the raw compound was subjected to a molding pressure of 250 - 720 Kg / cm2 for a period of 2 - 15 minutes.

[0120] Illustrative Example 3

[0121] In a first step, 367.9 g of potassium disilicate solution was mixed with 150 g of metakaolin (Argical M1000 from Imerys) at a mixing speed of 800 rpm for 10 minutes, using a mechanical stirrer to form a geopolymer solution.

[0122] In a subsequent step, 280 g of geopolymer premix was added to the geopolymer solution obtained from the previous step. The resulting slurry was mixed for 10 minutes.

[0123] The friction material has the composition of Table 4.

[0124] Table 4

[0125] Geopolymer premix (vol%) Aramid fiber 1-4 Rock fiber 6-11 Friction powder 0.5-3 Carbon 8-20 Rubber 1-4 Medium abrasive 5-7 Soft abrasive 9-12 Sulfur 3-9 Steel fiber 5-11 Inorganic binder 30-75 Total 100

[0126] SiO 2 / Al 2 O 3 is 5, the SiO2 ratio is 1.2, and the H 2 O / Al 2 O 3 ratio is 24.5.

[0127] The slurry obtained from the previous step was poured into a hot mold at 80 °C for consolidation. The resulting sheet was removed from the mold after 20 minutes.

[0128] Then the sheet was attached, for example, glued onto a backing plate (without inserting a conventional underlayer), and then cured at 80 °C for 12 hours.

[0129] If the geopolymer composition is different, the time and temperature may vary significantly.

[0130] Example 4 - Brake Test

[0131] The brake pads produced as described in Comparative Example 1, Comparative Example 2, and Illustrative Example 3 were subjected to the following tests:

[0132] The efficiency test has been carried out according to the standard AKM known to those skilled in the art. The efficiency test includes the following: settling braking; braking at different fluid pressures; cold (<50 °C) evaluation braking; simulated highway braking; two high-energy braking (first FADE test) series interspersed with a series of regenerative braking. According to this test, it is also possible to infer the wear suffered by the brake pads and brake discs using methods known to industrial technicians.

[0133] The results obtained are as Figure 3 shown, which schematically represents the extraction of important data of the experimental curves obtained. The standard LS curve corresponds to the brake pads of the friction material including Comparative Example 1, the GEO CS curve corresponds to the brake pads of the friction material including Comparative Example 2, and the GEO GC curve corresponds to the brake pads of the friction material including Illustrative Example 3.

[0134] At the end of the braking test, the brake pads and brake discs are disassembled, inspected and photographed, and the wear of both the brake pads and brake discs can be calculated. The brake pads produced according to Example 1 show very similar pad wear and disc wear to the brake pads of the comparative examples.

Claims

1. A method for manufacturing a braking element, the method sequentially comprising the following steps: a) Mixing an aluminosilicate source with an alkaline silicate solution to form a geopolymer solution; b) Adding a friction mixture to the geopolymer solution of the previous mixing step to obtain a slurry, wherein the geopolymer solution is an adhesive for the friction mixture; c) Casting the slurry in a mold at a temperature between room temperature and 120 °C without any pressure and maintaining the slurry inside the hot mold for a time including between 5 minutes and 2 hours until the slurry is substantially solidified; d) Demolding the solidified slurry to obtain a solid friction material sheet or block; e) As a result of the casting step or after the solid friction material sheet or block is demolded, attaching a backing plate to the solid friction material sheet or block; f) Curing the solid friction material sheet or block having the backing plate attached thereto at a temperature between 60 °C and 120 °C for a time between 1 hour and 24 hours, and wherein, combining the following: i) - Select the aluminosilicate source and the alkaline silicate in step a) such that the SiO 2 / Al 2 O 3 molar ratio in the final friction material is between 3 and 5; ii) - Select the said alkaline silicate solution in step a) such that the SiO 2 / R 2 molar ratio in the final friction material is between 0.7 and 1.5, and wherein R is selected from Na, K, Li; iii) - The adhesive present in the composite of the friction material in the form of a slurry is equal to or greater than 30% by volume, calculated based on the total volume of the composite.

2. The method according to claim 1, wherein, The aluminosilicate source is selected from the group consisting of metakaolin, kaolin, fly ash, bottom ash, and mixtures thereof.

3. The method according to claim 2, wherein, The aluminosilicate source includes metakaolin.

4. The method according to any one of the preceding claims 1 to 3, wherein, The alkaline silicate solution is selected from the group consisting of sodium silicate and sodium hydroxide systems, potassium hydroxide and potassium silicate systems, lithium hydroxide and lithium silicate systems, cesium hydroxide and cesium silicate systems, rubidium hydroxide and rubidium silicate systems, and mixtures thereof.

5. The method according to claim 1, wherein, The friction mixture includes: - Fibers, the fibers are selected from the group consisting of organic fibers, inorganic fibers, or metal fibers and mixtures thereof, and are added in an amount of 2% to 30% by volume of the total volume of the friction material; - Organic or inorganic fillers, based on the total composition of the friction material, the organic or inorganic fillers are added in an amount of 2% to 40% by volume; - Friction modifiers, the friction modifiers are added in an amount of 4% to 30% of the entire volume of the friction material.

6. The method according to claim 5, wherein, The fillers are selected from the group consisting of calcium carbonate, barium sulfate, magnesium oxide, calcium hydroxide, calcium fluoride, slaked lime, talc, mica, and mixtures thereof.

7. The method according to claim 1, wherein, Select the solution in step a) such that the H 2 O / Al 2 O 3 molar ratio is between 10 and 25.

8. The method according to claim 1, wherein, The braking element is a brake pad.

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