IT202000011716A1 - BRAKE PAD WITH A FRICTION MATERIAL HAVING A GEOPOLYMER BINDER - Google Patents

Description

BRAKE PAD WITH A FRICTION MATERIAL

HAVING A GEOPOLYMER BINDER

Context

Unless otherwise indicated herein, the materials disclosed in this section are not prior art with respect to the claims in this application and are not permitted as prior art for inclusion in this section.

[0002] The brake pads are part of a brake disc system used in vehicles. Conventionally there are two brake pads for each brake disc rotor. The brake pads are held in place and operated by a caliper that ? attached to a wheel hub. Brake pads often have steel back plates, wherein one surface of the steel back plates has a friction material which is ? facing the surface of the brake disc rotor. When the brakes are applied, the caliper compresses the two brake pads together on the brake disc rotor to slow and/or stop the vehicle. The brake pads convert the kinetic energy of the vehicle into frictional heat energy. Therefore friction materials play an important role in a braking system, as they Brakes use friction to decelerate/stop the vehicle.

[0003] Friction materials typically include reinforcements, friction modifiers and binders. The asbestos ? been widely used as a reinforcement for friction materials due to its stability? thermal. However, asbestos? highly toxic to human health. The asbestos ? been replaced often with numerous materials, including inorganic and organic materials, as well as? metal fibers. Metal sulfides such as molybdenum disulfide, iron sulfides, copper, tin, graphite and/or coke are exemplary materials that can be used as friction modifiers. The binders can be thermosetting polymers, such as phenolic resins. However, during repeated braking, organic binders can release volatile gas compounds or fine particles into the atmosphere, which can cause damage. be harmful to human health.

[0004] The present illustration shows that geopolymers are a class of materials which are synthesized by the reaction of an alumina-silicate powder with an alkaline siliceous solution at ambient temperature and pressure. Geopolymers have properties reasonable mechanics and good stability? thermal at temperatures above 1000 ?C and therefore may be suitable as alternative binders.

Summary

[0005] The previous summary ? illustrative only and is not intended to be restrictive in any way. In addition to the illustrative aspects, embodiments and features described above, further aspects, embodiments and features will become apparent with reference to the drawings, detailed description and claims.

[0006] According to some examples a method for synthesizing a geopolymer is described. The method can include mixing silica and methakaolin to form a premix; the preparation of a silicate solution; and mixing the silicate solution and the premix to form a wet blend, wherein the method is performed in the absence of an alkali and in the presence of water.

[0007] According to other examples, the mixing of silica and metakaolin can include a blend of about 10 wt% silica and about 90 wt% methakaolin. The mixing of silica and metakaolin can include mixing about 5 minutes to about 10 minutes in an Eirich blender or Loedige blender. The preparation of the silicate solution can? include adding sodium silicate or potassium silicate to the water. The preparation of the silicate solution can? include adding about 38 wt% sodium silicate to about 42 wt% water. The preparation of the silicate solution can? include adding sodium silicate to water; heating to a temperature up to 50 ?C; and stirring for about 2 to about 4 hours. The preparation of the silicate solution can? include preparing the silicate solution having a pH in the range of about 12 to about 14. include mixing for about 5 minutes to about 10 minutes in an Eirich blender or Loedige blender to form the wet mix. The synthesis of the geopolymer can include geopolymer synthesis without a phenolic resin.

[0008] According to further examples, a method for producing a friction material is described. The method can include mixing silica and methakaolin to form a premix; the mixing of the premix and a crude blend to form a dry blend, wherein the crude blend comprises one or more between inorganic, organic or metallic fibers, at least one friction modifier or lubricant and at least one filler or abrasive; the preparation of a silicate solution; and mixing the silicate solution and the dry mix to form the friction material, wherein the method is performed in the absence of an alkali and in the presence of water and wherein a reaction between the premix and the silicate solution forms a geopolymer.

[0009] According to still other examples, the mixing of silica and metakaolin can include a blend of about 10 wt% silica and about 90 wt% methakaolin. The mixing of silica and metakaolin can include mixing approximately 5 minutes to 10 minutes in an Eirich blender or Loedige blender. The preparation of the silicate solution can? include adding sodium silicate or potassium silicate to the water. The preparation of the silicate solution can? include adding about 38 wt% sodium silicate to about 42 wt% water. The preparation of the silicate solution can? include adding sodium silicate to water; heating to a temperature up to about 50 ?C; and stirring for about 2 to about 4 hours. The preparation of the silicate solution can? include preparing the silicate solution having a pH in the range of about 12 to about 14. include mixing for approximately 5-10 minutes in an Eirich blender or Loedige blender to form the wet blend. Mixing premix and raw mix to form dry mix can include blending 40% by weight of premix and about 60% by weight of crude blend. Mixing premix and raw mix can include mixing the premix and raw mix for about 5 minutes to about 10 minutes in an Eirich blender or Loedige blender. Adding the silicate solution to the dry mix can include adding about 32 wt% silicate solution to about 68 wt% dry mix. Adding the silicate solution to the dry mix to form the wet mix can include the formation of the wet mixture so that? has a moisture content? final of about 20% by weight.

[0010] According to yet further examples, a method for making a brake pad is described. The method can include the synthesis of a friction material; placing the friction material, a bottom layer and a backplate in a stamping press; molding at a temperature in the range of about 20?C to about 80?C to form a soft brake pad; applying a load to the soft brake pad, where the load is in the range of approx. 100 to approx. 200 kg; and curing in an oven to form the brake pad, wherein the synthesis of the friction material includes mixing silica and methakaolin to form a premix; the mixing of the premix and a crude blend to form a dry blend, wherein the crude blend includes one or more between inorganic, organic or metallic fibers, at least one friction modifier or lubricant and at least one filler or abrasive; the preparation of a silicate solution; and mixing the silicate solution and the dry mix to form the friction material, wherein the method is performed in the absence of an alkali and in the presence of water and wherein a reaction between the premix and the silicate solution forms a geopolymer.

[0011] According to other examples, molding can include a stamping for about 1 min and at a pressure in the range of about 100 kg/cm<2> to about 300 kg/cm<2>. The polymerization can include curing at a temperature in the range of about 150°C to about 160°C for at least about 30 min. The molding can be performed at a temperature in the range of about 20?C to about 80?C to form a soft brake pad with a Rockwell hardness substantially equal to zero. The application of the load can? include placing the soft brake pad between two metal plates fixed on four vertical rails and applying the load using a hydraulic press. The application of the load and the curing in the oven form the brake pad with a hardness of about 60 HRS, a compressibility? of about 0.1 mm and a gap of about 12.35 KN.

[0012] According to some examples, a braking system can include a brake disc rotor made of a metal; and a brake pad positioned on the brake disc rotor, wherein the brake pad comprises a friction material, the friction material comprises a geopolymer and the geopolymer ? free from alkali and phenolic resin. The geopolymer can include about 42 wt% metakaolin, about 20 wt% sodium silicate, about 5 wt% silica, and about 33 wt% water.

Brief description of the drawings

[0013] The foregoing and other features of this illustration will become more apparent. clearly from the following description and the appended claims taken in conjunction with the accompanying drawings. Provided that these drawings represent only various embodiments of the illustration and, therefore, are not to be construed as limiting its scope, the illustration will be specifically described? and additional details through the use of the attached drawings, in which:

Fig. 1 illustrates an exemplary brake pad including a friction material;

figure 2 ? a flowchart illustrating a method for synthesizing a geopolymer;

figure 3 ? a flowchart illustrating a method for synthesizing a friction material;

figure 4 ? a flowchart illustrating a method of making a brake pad;

figure 5 ? a schematic representation of a system for making a brake pad;

figure 6 ? a schematic representation of a Spannrahmen device for applying a load to a soft brake pad;

figure 7 ? a graph illustrating a measurement of the hardness of a brake pad; And

the figure 8? a graph illustrating a measurement of a coefficient of friction of a brake pad including the illustrated friction material and that of a brake pad including a low steel content steel friction material,

all arranged according to at least some embodiments described herein.

Detailed description of the invention

[0014] In the following detailed description reference is made to the accompanying drawings, which form a part hereof. In the drawings, like symbols typically identify like components, unless the context otherwise indicates. The illustrative embodiments disclosed in the detailed description, drawings and claims are not intended to be limiting. ? Other embodiments may be used and other modifications may be made without departing from the spirit or scope of the subject matter presented herein. The aspects of the present illustration, as described generally herein and illustrated in the figures, may be arranged, substituted, combined, separated, and designed in a wide variety of designs. of different configurations, all explicitly contemplated herein.

[0015] This illustration ? generally outlined for, among others, a geopolymer, a friction material, a brake pad, and brake pads that use a geopolymer-based friction material.

[0016] Briefly the technologies are described generally for a device, a system and a method for synthesizing a geopolymer. The method includes mixing silica and methakaolin to form a premix, preparing a silicate solution, and adding the silicate solution to the premix to form a wet mixture. The method is performed in the absence of an alkali and in the presence of water.

[0017] The present illustration recognizes that geopolymers can replace conventional organic binders used to make friction materials, which in turn are used to make the brake pad. Some examples of the advantages of the geopolymers illustrated herein are that they do not contain harmful phenolic resins. The geopolymers of the present illustration are relatively less expensive than the organic binders. Furthermore, the geopolymers illustrated herein allow the use of mild post-polymerization conditions (low pressures and ambient temperatures) to make the brake pads. Since geopolymers are made in the absence of an alkali, they possess low alkalinity.

[0018] The disclosed technologies further provide a method of making a friction material, which in turn is used to make a brake pad. The friction material includes the geopolymers illustrated herein. The friction material shown has minimal fluctuation in its effectiveness under varying conditions, such as speeds? of the vehicle, laden weight or temperature variation due to the use of the brake. The friction material shown ? stable even when exposed to different environmental conditions, including humidity, water and mud. The friction material shown is strong enough to resist thermal and mechanical alterations and is ? durable. Does the friction material shown have a conductivity? low temperature to prevent the brake pad or brake oil temperature from rising.

[0019] Due to the presence of the geopolymers illustrated in the friction materials, during repeated braking of a vehicle, it will not released into the atmosphere any quantity? substantial amount of gaseous compounds or harmful fine particles. Various tests were carried out on some brake pads made according to the present illustration. Brake pads can perform better than conventional brake pads when subjected to various physical tests such as compressibility, hardness and release. The brake pads also underwent efficiency tests according to AKM standards and showed improved efficiency. The AKM (Arbeit Kreis Master) standard refers to the European counterpart of a standard of the dynamometer testing standards working group. The US counterpart? known as SAE (Society of Automotive Engineers) J2522.

[0020] Figure 1 ? an exemplary brake pad 100 which includes a friction material 108 which is arranged in accordance with aspects of the present illustration. The exemplary brake pad 100 includes a shim 102, a back plate 104, a bottom layer 106, a friction material 108 and a friction surface 110. In some examples the brake pad has a sandwich structure. An example of a sandwich structure can? include a friction material 108, which generates friction when pushed towards a brake disc rotor (not shown), followed by the bottom layer 106 and backplate 104.

[0021] In various examples the thickness 102 can be a thin layer of rubber (or another elastomeric material) that ? configured to fit between the 100 brake pad and the brake disc rotor. ? Shim 102 can be used to correct any imperfections in the surfaces of the brake disc rotor and/or brake pad 102, which may otherwise produce noise. In some examples, the thickness of the brake 102 pu? act as an anti-vibration pad.

[0022] In some examples the rear plate 104 can be made of substantially rigid materials such as metals, ceramics or combinations thereof. Examples of rigid metals include steel, tungsten carbide, cast iron and titanium. Examples of rigid ceramics include zirconium oxide, aluminum oxide and silicon nitride.

[0023] In various examples the friction material 108 can be tied to the friction surface 110 that ? facing the brake disc rotor. Some examples of the friction materials 108 may include a geopolymer. The geopolymer in the friction material can? act as an inorganic binder. The geopolymer ? substantially free of phenolic resins. In some examples, even under adverse conditions such as repeated braking or high temperatures, the friction material containing a geopolymer may not release gaseous products and harmful fine particles into the atmosphere.

[0024] Figure 2 ? a flowchart illustrating a method for synthesizing a geopolymer that ? arranged in accordance with aspects of the present illustration. The method described 200 pu? include block 202, ?MIXING SILICA AND METAKAOLIN TO MAKE A PRE-MIXTURE?, block 204, ?PREPARING A SILICATE SOLUTION?, and block 206, ?ADD SILICATE SOLUTION TO THE PRE-MIX.?.

At block 202 the silica and metakaolin are mixed to form a premix. In an example at block 202 ? Approximately 10 wt% silica can be mixed with approximately 90 wt% metakaolin to form a premix. match Argical? M1000, in some examples. In one example the silica and methakaolin may be supplied as dry powders and may be mixed to a dry condition in a blender. The choice of the mixer can depend on the quantities? of powders to mix. In an example ? is it possible to use a mixer Eirich having a capacity? in a range from about 8 l to about 50 l. In some examples the silica and metakaolin may be mixed in a Loedige mixer having a capacity of about 25 litres. In an example, the mixing time can? be in the range of about 5 min to about 10 min.

[0026] The weight percentages of silica and metakaolin can be varied from the above example. In other examples, 6% by weight of silica can be mixed with about 94% by weight of metakaolin to form the premix. In yet further examples 12% by weight of silica can be mixed with approximately 88% by weight of metakaolin to form the premix. The weight percent of silica can? be in the range of about 2% to about 10% or alternatively in the range of about 5% to about 15%, etc. Also, in some examples, the weight percent of metakaolin can be in a range of about 80% to about 90% or alternatively in a range of about 85% to about 95%, etc.

[0027] Block 202 can be followed by block 204, in which a silicate solution can? be prepared by dissolving an alkali silicate in water. In some examples the alkaline silicate can? be sodium silicate. In some other examples the alkali silicate can? be potassium silicate. The water used can be Milli-Q water, deionized water, and even tap water. About 38% by weight of sodium silicate (or some other silicate) can be dissolved in about 62% by weight of water. The silicate solution can? be prepared on a hot plate with continuous stirring. In some examples the? agitation pu? last for about 2 hours. In other examples the? agitation pu? last for about 4 hours. ? Is it possible to increase the temperature of the silicate solution up to about 50?C to enhance the solubility? of sodium silicate in Milli-Q water, deionized water, and even tap water. The sodium silicate solution can have a pH in the range of about 12 to about 14.

[0028] The weight percentages of alkali silicate and water can be varied from the above example. In other examples 32% by weight of silicate can? be mixed with about 68% by weight of water to form the silicate solution. In still other examples 40% by weight of silicate can be mixed with about 60% by weight of water to form the silicate solution. The percentage by weight of silicate pu? be in the range of about 30% to about 50% or alternatively in the range of about 32% to about 47%, etc. Also, in some examples, the percent by weight of water can be be in a range of about 50% to about 70% or alternatively in a range of about 55% to about 65%, etc.

[0029] Block 204 can be followed by block 206, where the silicate solution can? be added to the premix prepared at block 202 to form a wet mix. The wet mix can have a moisture content? about 20% (or alternatively in the range of about 15% to about 25%). The choice of the mixer can depend on the quantities? of powders to mix. In an example ? is it possible to use a mixer Eirich having a capacity? in a range from about 8 l to about 50 l. In some examples the silica and metakaolin may be mixed in a Loedige mixer having a capacity of about 25 litres. The geopolymer can be formed by a reaction between the premix and the silicate solution.

[0030] Figure 3 ? a flowchart illustrating a method for synthesizing a friction material that ? arranged according to at least some embodiments described herein. The described method 300 pu? include block 302, ?MIXING SILICA AND METAKAOLIN TO MAKE A PRE-MIXTURE?, block 304, ?MAKE A RAW MIX?, block 306, ?MIXING PRE-MIX AND RAW MIX TO MAKE A DRY MIX?, block 308, ?PREPARING A SILICATE SOLUTION?, and block 310, ?ADD SILICATE SOLUTION TO DRY MIX TO FORM WET MIX?.

At block 302 the silica and methakaolin can be mixed to form a premix. In an example ? It is possible to mix about 10% by weight of silica with about 90% by weight of methakaolin to form a premix. Metakaolin? Argical M-1000?. In one example the silica and methakaolin may be supplied as dry powders and may be mixed to a dry condition in a blender. The choice of the mixer can depend on the quantities? of powders to mix. In an example ? is it possible to use a mixer Eirich having a capacity? in a range from about 8 l to about 50 l. In some examples the silica and metakaolin may be mixed in a Loedige mixer having a capacity of about 25 litres. In an example, the mixing time can? be in the range of about 5 min to about 10 min.

[0032] Block 302 can be followed by the block 304, in which pu? be prepared a crude mixture. The preparation of the raw mixture can? understand ingredient dispensing and inspection, ingredient weighing, and ingredient mixing. In various examples the raw blend ingredients may be inorganic, organic and/or metallic fiber materials, at least one friction modifier or lubricant, and at least one filler material or abrasive material.

[0033] In various examples the inorganic fiber materials may consist of rock wool, fiber wool, wollastonite or glass fiber. In some examples the organic fibers may consist of aramid fibers or carbon fibers. In additional examples the metal fiber materials that are used may be composed of copper fibers, tin fibers, iron fibers and/or aluminum fibers. In some other examples ? It is possible to use steel, bronze or brass in powder or fiber form. In some examples ? It is possible to use a combination of inorganic, organic and metallic fibers. In various examples the friction modifiers may consist of metal sulfides such as molybdenum disulfide, sulfides of iron, copper, tin, graphite and/or carbon or a combination thereof. In other examples the filling material can? consist of barite (barium sulfate), calcium carbonate, talc, magnesium oxide, vermiculite, or a combination thereof. In additional examples, the abrasive can? consist of zirconium silicate, zirconium oxide, alumina, silicon carbide, mica, or a combination thereof.

[0034] Block 304 can to be followed by block 306, wherein the raw mix and premix may be mixed to form a dry mix. ? It is possible to supply the premix and raw mix as dry powders. The raw blend and premix can be blended in a blender for about 5 min to about 10 min to form a dry blend. The choice of the mixer can depend on the quantities? of powders to mix. In an example ? is it possible to use a mixer Eirich having a capacity? in a range from about 8 l to about 50 l. In some examples the premix and raw mix may be blended in a Loedige mixer having a capacity of about 25 litres. In some examples the ratio of the raw mix to the premix can correspond to about 60% by weight of the raw mix to about 40% by weight of premix. In additional examples the portion of raw mix can? ranging from about 50% by weight to about 75% by weight; while the portion of premix can? comprise between about 50% and about 25% of the overall blend.

[0035] Block 306 can be followed by the block 308, in which pu? a silicate solution be prepared. In some examples the silicate solution can? be prepared by dissolving an alkali silicate in water. The alkaline silicate can? be sodium silicate, potassium silicate or another silicate. The water used can be Milli-Q water, deionized water, and even tap water. The silicate solution can? be prepared on a hot plate with continuous stirring. In some examples the? agitation pu? last for about 2 hours. In other examples the? agitation pu? last for about 4 hours. ? Is it possible to increase the temperature of the silicate solution up to about 50?C to enhance the solubility? of sodium silicate in Milli-Q water, deionized water, and even tap water. The sodium silicate solution can have a pH in the range of about 12 to about 14. In some examples, the ratio of alkali silicate to water can? correspond to about 38 wt% alkali silicate (e.g., sodium silicate) and about 62 wt% water. In additional examples the alkali silicate portion can? ranging from about 30% by weight to about 40% by weight; while the portion of? water pu? comprise between about 60% and about 70% of the overall blend.

[0036] Block 308 can be followed by block 310, in which the silicate solution can? be added to the dry mix prepared at block 306 to form a wet mix. The wet mix can have a moisture content? final about 20%; even if other moisture content? acceptable can be in the range of about 15% to about 30%. The choice of the mixer can depend on the quantities? of the silicate solution and the dry mix to mix. In an example ? is it possible to use a mixer Eirich having a capacity? in a range from about 8 l to about 50 l. In some examples ? Is it possible to use a Loedige mixer having a capacity? of about 25 litres. The wet mix can be the friction material having the geopolymer binder. The geopolymer can be formed as a result of a reaction between the premix and the silicate solution. The geopolymer binder can harden the raw mixture and pu? form the friction material with the? intensity? request.

[0037] Figure 4 ? a flowchart illustrating a method 400 for making a brake pad which ? arranged according to at least some embodiments described herein. The described method 400 pu? include block 402, ?SYNTHESIZING A FRICTION MATERIAL?, block 404, ?PLACING FRICTION MATERIAL, A BOTTOM LAYER, AND A BACK PLATE IN A STAMPING PRESS?, block 406, ?PRINTING AT A TEMPERATURE IN A RANGE BETWEEN APPROXIMATELY 20 ?C TO ABOUT 80 ?C TO FORM A SOFT BRAKE PAD?, block 408, ?APPLICING A LOAD TO THE SOFT BRAKE PAD?, and block 410, ?CURING THE BRAKE PAD IN AN OVEN?.

[0038] At block 402 the friction material can be synthesized according to a method as described in Figure 3. Block 402 can? be followed by block 404, where the preweighed friction material along with a bottom layer and backplate can be placed in a stamping press. In an example, the lower layer pu? have viscous polymers which may be able to transform mechanical energy into thermal energy when the brakes are applied in the vehicle. In various examples ? possible to place the bottom layer between the friction material and the back plate. The bottom layer can bond the friction material with the back plate. The bottom layer can also provide a moisture barrier? and can adjust the compressibility? of the brake pad.

[0039] Block 404 can to be followed by block 406, in which the friction material, bottom layer, and backplate can be molded at a temperature in the range of about 20?C to about 80?C. The stamping press can be closed and can? compress the friction material, underlay and backplate together at any appropriate temperature, such as room temperature, by actuating a punch provided in the stamping press. because the stamping press can? be operated at room temperature, in some examples, the operation can? be called ?cold forging?. In various examples, the pressure applied in the stamping press can be around 250 kg/cm<2>. In some examples ? You can apply pressure for about a minute. Stamping/compression in the stamping press may be required to form the soft brake pad. The soft brake pad produced in this way can? have a Rockwell hardness of approximately zero.

[0040] Block 406 can be followed by block 408, in which a load can? be applied to the soft brake pad. The soft brake pad can? require a period of maturation under pressure to obtain the required hardness. In addition, the soft brake pad can? take time under pressure to allow the friction material ingredients to react and improve the compaction of the materials. In some examples the soft brake pad can? be left at room temperature for a few days. In some other examples the soft brake pad can? be left at room temperature for more? of five days.

[0041] The pressure can be applied to the soft brake pad using a Spannrahmen device, a device made by hand. In a Spannrahmen device ? It is possible to use two metal plates and springs to apply the load. The applied load can? be in a range of 100 to 200 kg. The Spannrahmen device can? be formed by two metal plates fixed on four vertical walls. ? is it possible to load four springs using a hydraulic press that can? press on a third plate to distribute the load evenly on the springs. The springs can press the plates which in turn press the soft brake pad to form a pre-cured brake pad with the hardness and compressibility of the brake pad. requests.

[0042] Block 408 can be followed by block 410, in which the pre-cured brake pad can? be cured in an oven. In some examples, the polymerization temperature can? be in the range of approximately 150?C to approximately 160?C, although other temperatures are contemplated and may be adjusted based on the specific brake pad materials. ? It is possible to cure the brake pad for an appropriate cure period, such as about 30 min or another cure period in the range of from about 20 min to about 45 min. The heat applied to the brake pad during the curing time can activate and solidify the fibers, geopolymer and other ingredients of the friction material. The pressure applied in the Spannrahmen device and the specific curing temperature may be required for adhesive activation and release improvement. During the polymerization the lower layer can? be adhered snugly to the backplate with substantially no detachment.

[0043] Figure 5 ? a schematic representation of an exemplary system 500 for making a brake pad which is arranged according to at least some embodiments described herein. The system described 500 pu? include multiple devices such as a mixer 502, a molding press 504, a Spannrahmen device 506 and a furnace 508.

[0044] A controller (not shown) can? be used to coordinate the operation of the system 500, such as via software instructions which, when executed by a processor in the controller, coordinate the operation of each of the devices for times, temperatures, and other process-based parameters specific to the devices. Therefore each of the devices described in the 500 system can? be configured and operated in response to signals (e.g., analog or digital signals) from the controller. In addition, conveying systems (not shown) such as belt conveyors and other robot-operated conveyors can be used, configured and operated by the controller for transfer between the various devices.

[0045] In an exemplary configuration the mixer 502 can? be configured to mix a premix, raw mix, and silicate solution to form a wet mix 512. depend on the quantities? to mix. In an example ? is it possible to use a mixer Eirich having a capacity? in a range from 8 to 50 l. In some examples ? Is it possible to use a Loedige mixer having a capacity? of 25l.

[0046] A preweighed wet mix 512 together with a bottom layer and backplate can be placed in a 504 stamping press and can? be printed at a temperature in the range of about 20?C to about 80?C. The 504 stamping press can? be closed and can? be configured to compress the friction material, underlay and backplate together at room temperature by actuating a punch provided in the 504 stamping press. be around 250 kg/cm<2>. In some examples ? You can apply pressure for about a minute. The brake pad in this phase pu? have a Rockwell hardness of approximately zero and can? be called a 514 soft brake pad.

[0047] A Spannrahmen 506 device can? be configured to apply a load to the 514 soft brake pad. The 514 soft brake pad can? require a period of maturation under a pressure (load) to obtain the required hardness. The 514 soft brake pad can? take additional time under pressure to allow the friction material ingredients to react and improve the compaction of the materials. In some examples the soft brake pad 514 can? be left at room temperature for a few days. In some examples the soft brake pad 514 can? be left at room temperature for more? of five days.

[0048] The pressure can be applied to the soft brake pad 514 using a Spannrahmen device 506, a device made by hand. In the device Spannrahmen 506 ? It is possible to use two metal plates and springs to apply the load. The applied load can? be in a range of 100 to 200 kg. The Spannrahmen 506 device can? be formed by two metal plates fixed on four vertical walls. ? is it possible to load four springs using a hydraulic press that can? press on a third plate to distribute the load evenly on the springs. The springs can press down on the plates which in turn press down on the soft brake pad resulting in a 516 pre-cured brake pad of the hardest and compressibility you can expect. requests.

[0049] ? It is possible to cure the pre-cured brake pad 516 in an oven 508 at a curing temperature in the range of about 150°C to about 160°C for a period of time (curing time) of about 30 minutes to form a brake pad 518. The 518 brake pad can? have a hardness rating of about 55.9 HRS, a compressibility rating? of approximately 0.1 mm and a peel rating of approximately 12.35 kN (a force required to separate the pad layers).

[0050] Figure 6 ? a schematic representation of a Spannrahmen device for applying a load to a soft brake pad. The Spannrahmen 600 device ? a device made by hand and ? configured to apply a load on the soft brake pad 610. The Spannrahmen device 600 includes two metal plates 602 and four springs 604 which can be used to apply the load. The applied load can? be in the range of about 100 kg to about 200 kg. The Spannrahmen 600 device can? be formed by two metal plates 602 fixed on four vertical walls 606. Is it possible to load four 604 springs using a hydraulic press (not shown) which can? press on a third plate 608 to distribute the load evenly over the springs 604. The springs can be configured to press the two metal plates 602 which in turn press the soft brake pad 610 resulting in a pre-cured brake pad 610 hardness and compressibility? requests.

[0051] Figure 7 ? a graph 700 illustrating a hardness measurement of a brake pad including the illustrated friction material. In the graph 700 the vertical axis 702 represents the hardness and the horizontal axis 704 represents the time spent in the Spannrahmen device (in hours). In graph 700, the hardness value increases linearly from zero to a value of approximately 60 over an elapsed time of approximately 50 hours and then the hardness rating decreases from an elapsed time of approximately 50 hours to approximately 120 hours, slowly stabilizing at a hardness value of approximately 75 at approximately 150 hours. The hardness value remains substantially constant thereafter, as illustrated by the elapsed time from about 125 hours to about 250 hours.

[0052] The hardness test is performed according to the Rockwell test protocol, which measures a depth penetration of an indenter with a large load (higher load) compared to the penetration achieved with a preload (smaller load). The Rockwell scale? a scale of hardness based on the indentation hardness of a material. The classification used as HRS indicates that the indenter ? a steel ball.

[0053] Figure 8 ? a graph 800 illustrating a measurement of a coefficient of friction of a brake pad, which includes the illustrated friction material, compared to a conventional brake pad, which includes a standard low steel content friction material.

[0054] The vertical axis 802 represents a coefficient of friction and the horizontal axis 804 represents various standard tests. Graph 806 shows the variation in the coefficient of friction over various tests for a brake pad that includes the friction material shown. Graph 808 shows the variation of the coefficient of friction over various tests for a brake pad that includes LS material according to the AKM standard. Both brake pads had a similar average coefficient of friction.

[0055] Braking materials can be tested in vehicle crash tests or in a large-scale dynamometer. In dynamometer tests ? It is possible to test the real pad or rotor in protocols that simulate the conditions required to stop a vehicle. ? It is possible to use different standards such as the SAE J2522 standard developed by the AK Working Group (AKM), which represents European car brake manufacturers. The tests evaluate the effectiveness of the brake pad and rotor system under different conditions of speed, temperature, pressure and deceleration.

[0056] Some of the physical parameters used by dynamometers (for example, according to the SAE J2522 standard) include the contact pressure between the pad and the rotor, the deceleration, the speed? of flow and the initial temperature. The tests focus on deceleration, where the vehicle is simulated during standstill or reduced speed conditions. (For example, many of the SAE J2522 test phases use braking from 80 km/h to 30 km/h by applying 3,000 kPa in the fluid line which applies force to the caliper).

[0057] The J2522 protocol includes 15 different main steps and many other sub-steps aimed at evaluating the frictional performance of brake materials under various conditions. An exemplary and non-exhaustive list of test phases can be include the Green feature ? (30 cycles): braking 80-30km/h, 380N; burnishing (192 cycles): braking from 80 to 30 km/hour, varying the applied load; characteristic value 1: (6 cycles): braking 80-30 km/h, 380 N; the sensitivity? of speed?/pressure at 40 km/hour (8 cycles): braking of 40-5 km/hour, varying the load; the sensitivity? of speed?/pressure at 80 km/hour (8 cycles): braking of 8040 km/hour, varying the load; the sensitivity? of speed?/pressure at 120 km/hour (8 cycles): braking of 120-80 km/hour, varying the load; cold application: 1 stop at 40-5 km/h, 380 N; fading 1: 15 stops of 100-5km/h, 500N; and recovery 1 (18 cycles): braking 80-30 km/h, 380 N.

Examples

[0058] The following examples are intended as illustrative and not limiting and represent specific embodiments of the present illustration. The examples illustrate that the geopolymers illustrated are substantially free of phenolic resins. In addition the examples demonstrate that the friction materials are synthesized using the geopolymers illustrated. Additionally, the examples demonstrate that brake pads including the illustrated friction materials have a hardness, compressibility, and stiffness. and a high gap.

Example 1

Synthesis of a geopolymer

[0059] Table 1 presents an exemplary formula for geopolymer synthesis. Was the metakaolin used Argical? M1000. 98% sodium silicate ? was obtained from Sigma. The water used was Milli-Q water and the other type of water. 10.3% by weight of silica ? been mixed with 89.7% by weight of metakaolin in an Eirich blender having a capacity? of 50l. The mixing time was between 5 and 10 min.

[0060] The sodium silicate solution ? was prepared by dissolving 37.5 wt% sodium silicate in 62.5 wt% water with continuous stirring for about 2 to about 4 hours on a hot plate. The temperature ? was raised up to 50 ?C to ensure that the sodium silicate was completely soluble in water. The sodium silicate solution has a pH in the range of about 12 to about 14. was added to the silica-methakaolin mixture and blended in the Eirich blender to form a geopolymer.

TABLE 1

Example 2

Synthesis of a friction material

[0061] 10.3% by weight of silica? was blended with 89.7 wt% metakaolin in a 50 L Eirich blender to form a premix. The mixing time was between 5 and 10 min. 58.5% by weight of a crude blend ? was mixed with 41.5 wt% premix to form a dry blend. The raw blend had pre-selected components including fibers, fillers, friction modifiers and abrasives.

[0062] The sodium silicate solution ? was prepared by dissolving 37.5 wt% sodium silicate in 62.5 wt% water with continuous stirring for about 2 to about 4 hours on a hot plate. The temperature ? was raised to about 50?C to ensure that the sodium silicate was completely soluble in water. The sodium silicate solution has a pH in the range of about 12 to about 14.

[0063] The 31.7% by weight of sodium silicate solution is was blended with 68.3 wt% of the dry blend in an Eirich blender for about 5 to about 10 min to form a wet blend. Does the wet mix have a moisture content of final by about 20%.

Example 3

Brake pads

[0064] The pre-weighed friction material together with a bottom layer and a back plate ? was placed in a stamping press and printed at room temperature. The friction material? been prepared as described in example 2. A pressure of about 250 kg/cm<2 >? been applied for about one minute in the molding press. The soft brake pad thus produced had a Rockwell hardness of zero. ? a load of between about 100 kg and about 200 kg was applied using the Spannrahmen device. Soft brake pad? been left in the device Spannrahmen at room temperature for more? of five days. The pre-cured brake pad? been cured in an oven. The polymerization temperature was in the range of about 150?C to 160?C. The pre-cured brake pad? polymerized for about 30 minutes at this temperature. The brake pad after curing had a hardness of 55.9 HRS, a compressibility? of 0.1 mm and a detachment of 12.35 kN.

[0065] The present illustration is not to be limited in terms of the specific embodiments disclosed in this application, which are intended as illustrations of various aspects. Many modifications and variations can be made without departing from its spirit and scope. Functionally equivalent methods and apparatus within the scope of the illustration, other than those listed herein, are possible from the foregoing descriptions. Such modifications and variations are intended to fall within the scope of the appended claims. This illustration is to be limited only by the terms of the appended claims, together with the entire scope of equivalents to which those claims are entitled. The terminology used herein is only intended to describe specific embodiments and not ? understood as limiting.

[0066] The subject matter described herein sometimes illustrates different components contained within, or connected with, other different components. Such architectures shown are only examples and, in fact, many other architectures that achieve the same functionality can be implemented. In a conceptual sense, any arrangement of components to achieve the same functionality? ? ?associated? actually in such a way that the functionality is obtained? desired. Therefore, any two components herein combined to achieve a feature? specification can be considered ?associated? l?to?the other so that the functionality? desired is obtained, regardless of the architectures or intermediate components. Similarly, any two components cos? associated can also be considered ?operationally connected?, or ?operationally coupled?, to one?other to obtain the functionality? desired, and any two components capable of being associated in such a way can also be considered ?operably coupled? the one?the other to get the functionality? desired. Specific examples of operationally matable components include, but are not limited to, physically connectable and/or physically interacting components and/or components that can wirelessly interact and/or interact wirelessly and/or components that logically interact and/or can interact logically.

[0067] With respect to the use of substantially any plural and/or singular term herein, those skilled in the art may switch from plural to singular and/or from singular to plural such as ? appropriate to the context and/or application. The various singular/plural permutations may be expressly stated herein for the sake of clarity.

In general, terms used herein and particularly in the appended claims (e.g., the bodies of the appended claims) are generally understood to be ?open? (for example, the term ?included? must be interpreted as ?included in a non-limiting way?, the term ?having? must be interpreted as ?having at least?, the term ?include? must be interpreted as ?include in a non-limiting way ?, etc.). Sar? It is also understood by those skilled in the art that if a specific number of an introduced claim statement is intended, that intention will be the same. formulated explicitly in the claim, and in the absence of such formulation it is not present this intention. For example, as an aid to understanding, the following appended claims may contain the use of the introductory phrases ?at least one? and ?one or more? to introduce the claim statements. However, the use of such expressions should not be interpreted as implying that the introduction of a claim statement with indefinite articles ?one? or ?a? limits a specific claim containing such introduced claim statement to embodiments containing only such statement, even when the same claim includes the introductory phrases ?one or more? or ?at least one? and indefinite articles like ?one? or ?a? (for example, ?one? and/or ?un? are to be interpreted as ?at least one? or ?one or more??), and the same is true for the use of definite articles used to introduce claim statements. In addition, even if a specific number of an introduced claim statement is explicitly stated, those skilled in the art will recognize that such statement should be interpreted to mean at least the statement number (e.g., the statement "two statements" alone, with no other modifiers , indicates at least two formulations, or two or more formulations).

[0069] Furthermore, in cases where a convention analogous to ?at least one of A, B and C, etc.? is used, in general this construction ? understood as a person skilled in the art would understand the convention (e.g., ?a system having at least one of A, B, and C? includes, but is not limited to, systems that have only A, B, or C, A and B together, A and C together, B and C together and/or A, B and C together, etc.). Sar? It is also understood by those skilled in the art that virtually any disjunctive word and/or expression that features two or more? alternative terms, in the description, in the claims or in the drawings, must be understood to understand the possibilities? to include only one term, one of two terms, or both terms. For example, the sentence ?A or B? will be understood to include the possibilities? of ?A? or ?B? or ?A and B?.

[0070] For all purposes, for example in terms of providing a written description, all ranges illustrated herein also encompass any possible sub-range and related combination of sub-ranges. Any range listed can be recognized easily to describe sufficiently and allow the subdivision of the same interval into at least equal halves, thirds, fourths, fifths, tenths, etc. As a non-limiting example, each range discussed herein can? be readily subdivided into a lower, middle, and upper third, etc. How will it be? even understood by one skilled in the art, all expressions such as ?up to?, ?at least?, ?greater than?, ?less than? and the like include the formulated number and refer to ranges which can be subsequently divided into sub-ranges as discussed above. Finally, a range includes each individual element. Thus, for example, a group having 1-3 cells refers to groups having 1, 2 or 3 cells. Similarly, a group having 1-5 cells refers to groups having 1, 2, 3, 4 or 5 cells, and so on? Street.

While various aspects and embodiments have been disclosed herein, other aspects and embodiments are possible. The various aspects and embodiments disclosed herein are for illustrative purposes and are not intended to be limiting, the true scope and spirit being indicated by the following claims.

Claims (10)

1. A method for synthesizing a geopolymer, wherein the method comprising: mixing silica and metakaolin to form a premix; prepare a silicate solution; And mixing the silicate solution and the premix to form a wet blend, wherein the method is performed in the absence of an alkali and in the presence of water. The method of claim 1 wherein the blending of silica and methakaolin comprises blending about 10% by weight silica and about 90% by weight methakaolin. The method according to claim 1 or claim 2, wherein the preparation of the silicate solution comprises: adding sodium silicate to water; heating to a temperature up to 50 ?C; And stirring for about 2 to about 4 hours. The method according to any preceding claim, wherein the preparation of the silicate solution comprises preparing the silicate solution having a pH in the range of from about 12 to about 14. The method according to any one of the preceding claims, wherein the synthesis of the geopolymer comprises the synthesis of the geopolymer without a phenolic resin. 6. Method of making a friction material, where the method includes: mixing silica and metakaolin to form a premix; the mixing of the premix and a crude blend to form a dry blend, wherein the crude blend comprises one or more between inorganic, organic or metallic fibers, at least one friction modifier or lubricant and at least one filler or abrasive; the preparation of a silicate solution; And the mixing of the silicate solution and the dry mix to form the friction material, wherein the method is performed in the absence of an alkali and in the presence of water and wherein a reaction between the premix and the silicate solution forms a geopolymer. The method of claim 6 wherein the blending of silica and methakaolin comprises blending about 10% by weight silica and about 90% by weight methakaolin. The method according to claim 6 or claim 7, wherein the preparation of the silicate solution comprises preparing the silicate solution having a pH in the range of from about 12 to about 14. 9. Braking system including: a brake disc rotor made of a metal; And a brake pad placed on the brake disc rotor, wherein the brake pad comprises a friction material, the friction material comprises a geopolymer e the geopolymer ? free from alkali and phenolic resin. The braking system of claim 9 wherein the geopolymer comprises about 42 wt% metakaolin, about 20 wt% sodium silicate, about 5 wt% silica, and about 33 wt% of water.