CN111779782A

CN111779782A - High-stability friction-resistant brake pad and production process thereof

Info

Publication number: CN111779782A
Application number: CN202010696769.7A
Authority: CN
Inventors: 蔡晓洋
Original assignee: Hangzhou Annat Industrial Co ltd
Current assignee: Hangzhou Annat Industrial Co ltd
Priority date: 2020-07-20
Filing date: 2020-07-20
Publication date: 2020-10-16
Anticipated expiration: 2040-07-20
Also published as: CN111779782B

Abstract

The invention discloses a high-stability friction-resistant brake pad which is prepared from the following raw materials in parts by weight: 5-15 parts of phenolic resin/carbon fiber composite material, 5-10 parts of coke powder, 10-15 parts of barite powder, 2-5 parts of silicon nitride composite filler, 2-5 parts of polyacrylonitrile fiber and 0.5-1.5 parts of calcium titanate fiber; the invention also discloses a production process of the high-stability friction-resistant brake pad; the prepared phenolic resin/carbon fiber composite material has excellent wear resistance of carbon fibers and thermal stability of modified phenolic resin, the prepared brake pad is prevented from being worn or decomposed due to temperature rise under the action of friction, and the composite filler and the phenolic resin/carbon fiber composite material are mixed to serve as a wear-resistant base material, so that an interface layer of the brake pad can be enhanced, and the brake pad is endowed with excellent wear resistance.

Description

High-stability friction-resistant brake pad and production process thereof

Technical Field

The invention belongs to the technical field of brake pad preparation, and particularly relates to a high-stability friction-resistant brake pad and a production process thereof.

Background

In the existing brake pad, the common phenolic resin has the defect of poor heat ablation, and when the brake pad is braked, the brake pad is heated due to friction, so that the phenolic resin is easy to generate physical and chemical changes, the brake performance of the brake pad in a high-temperature state is changed, and the thermal stability is poor; moreover, copper fibers are often added into some friction materials with low steel formula, and brake pads made of the friction materials containing the copper fibers easily generate copper-containing dust in the process of braking friction, and the copper-containing dust can enter the environment through air, rainwater, suspended particles and the like to cause environmental pollution and further cause potential safety hazards; in addition, in the brake pad made of asbestos, the asbestos brake pad can release toxic gas when the brake temperature reaches over 1000 ℃, and in the long-term use process of the asbestos brake pad, because the asbestos has carcinogenic effect, potential safety problems also exist; in addition, in the use process of the semimetal brake pad friction material, the problems that the brake pad is damaged, the brake pad and a brake disc (drum) are rusted and sticky, and the friction performance of the brake pad is unstable are easily caused, so that the friction performance is not good enough, and the problems that the high temperature resistance is poor, the temperature change becomes sensitive and the thermal stability is not good enough are easily caused.

Chinese patent CN102350498A discloses a C/C composite material brake pad and a preparation method thereof. The brake pad made of the C/C composite material is characterized in that: the lining material of the brake pad comprises the following components in percentage by weight: 50-65% of short carbon fiber, 10-25% of graphite, 5-15% of asphalt, 5-10% of copper powder and 5-10% of titanium powder. On one hand, the C/C composite material is prepared by a hot-pressing sintering method, the pressurization and sintering are integrated, and the process is simple; on the other hand, copper and titanium are added for alloying in the sintering process, so that the sintering temperature is reduced, and the friction performance is improved; adding titanium powder to react with C to generate TiC, so as to improve the friction coefficient; copper powder is added and uniformly dispersed in the composite material, so that the heat dissipation rate is improved; the graphite is used as a lubricating component to protect the dual and stabilize the friction coefficient, so that the produced brake pad has small abrasion to the dual disc and stable friction coefficient.

Disclosure of Invention

In order to overcome the technical problems, the invention provides a brake pad with high stability and friction resistance and a production process thereof.

The phenolic resin/carbon fiber composite material prepared by the invention has excellent wear resistance of carbon fiber and thermal stability of modified phenolic resin, prevents the prepared brake pad from being worn or decomposed due to temperature rise under the action of friction, and the composite filler is mixed with the phenolic resin/carbon fiber composite material to be used as a wear-resistant base material, so that the interface layer of the brake pad can be enhanced, and the brake pad is endowed with excellent wear resistance.

The purpose of the invention can be realized by the following technical scheme:

a high-stability friction-resistant brake pad is prepared from the following raw materials in parts by weight: 5-15 parts of phenolic resin/carbon fiber composite material, 5-10 parts of coke powder, 10-15 parts of barite powder, 2-5 parts of silicon nitride composite filler, 2-5 parts of polyacrylonitrile fiber and 0.5-1.5 parts of calcium titanate fiber;

the brake pad with high stability and friction resistance is prepared by the following method:

firstly, adding a phenolic resin/carbon fiber composite material, coke powder, barite powder, a silicon nitride composite filler, polyacrylonitrile fiber and calcium titanate fiber into a mixer, and uniformly mixing to prepare a mixture;

secondly, adding the mixture into a press machine for pressing to obtain a semi-finished product of the brake pad, controlling the pressing temperature to be 150-;

and thirdly, performing heat treatment on the semi-finished product of the brake pad, controlling the heat treatment temperature to be 170-180 ℃, and the heat treatment time to be 5-8h, and then performing flat chamfer, outer arc roughing, inner arc grinding, drilling and outer arc fine grinding to obtain the high-stability friction-resistant brake pad.

Further, the phenolic resin/carbon fiber composite material is prepared by the following method:

step S1, adding melamine and phenol into a three-neck flask, magnetically stirring at the rotation speed of 100-120r/min for 15min, heating to 45-50 ℃, dropwise adding oxalic acid, controlling the dropwise adding speed of the oxalic acid to be 3-5mL/min, heating to 55-60 ℃ after the dropwise adding is finished, continuously stirring for 30min, dropwise adding a formaldehyde solution with the mass fraction of 10%, and controlling the dropwise adding time to be 10-15min to obtain a mixed solution A;

step S2, transferring the mixed solution A into a reflux condenser, dropwise adding dilute hydrochloric acid with the mass fraction of 10% to adjust the pH until the pH =4-5, heating to 85-90 ℃, reacting for 5-6h at the temperature, then carrying out reduced pressure distillation, carrying out reduced pressure rotary distillation at 90-95 ℃ until the mixed solution A is not layered, and then purifying with tetrahydrofuran for three times to obtain modified phenolic resin;

step S3, adding the carbon fibers into concentrated sulfuric acid with the volume fraction of 98% for soaking for 2 hours, taking out the carbon fibers, washing the carbon fibers to be neutral by using deionized water, adding the carbon fibers into KH550 with the mass fraction of 2% for soaking for 3 hours, and washing and drying the carbon fibers to obtain the treated carbon fibers; and (4) adding the modified phenolic resin prepared in the step (S2) into absolute ethyl alcohol according to the weight ratio of 1: 10, and then adding hexamethylene tetramine to prepare a mixed solution B, wherein the weight ratio of the modified phenolic resin to the hexamethylene tetramine is 1: 0.1-0.2.

And S4, adding the treated carbon fiber into the mixed solution B, performing ultrasonic oscillation for 25-30min, taking out, drying at 40-50 ℃, performing hot-press molding, controlling the hot-press temperature to be 100-110 ℃ and the pressure to be 10MPa, and preparing the phenolic resin/carbon fiber composite material, wherein the weight ratio of the treated carbon fiber to the mixed solution B is controlled to be 1: 5-8.

In the step S1, firstly, melamine and phenol are mixed in a three-neck flask, then oxalic acid and 10% formaldehyde solution are sequentially added dropwise to prepare a mixed solution A, the mixed solution A is actually the phenolic resin modified by the melamine, and nitrogen heterocycle is introduced in the preparation process of the modified phenolic resin, so that the thermal decomposition temperature of the phenolic resin can be increased, and the finally prepared brake pad is prevented from being decomposed when the temperature is raised by friction to influence the service life of the brake pad; purifying the modified phenolic resin by tetrahydrofuran in step S2; soaking the carbon fiber in concentrated sulfuric acid for 2h in step S3, improving the activity of the surface of the carbon fiber and increasing the contact surface area of the carbon fiber through acid treatment, and then transferring the carbon fiber to KH550 for soaking for 3h to prepare the treated carbon fiber, wherein the surface of the carbon fiber has higher reactivity and can generate chemical bonds after being combined with phenolic resin so as to achieve the combination stability; then adding carbon fibers into the mixed solution B, drying, hot-pressing and molding to obtain the phenolic resin/carbon fiber composite material; the material has excellent wear resistance of carbon fiber and thermal stability of modified phenolic resin, and can prevent the prepared brake pad from being worn or decomposed due to temperature rise under the action of friction.

Further, the weight ratio of the melamine, the phenol, the oxalic acid and the 10% formaldehyde solution in the step S1 is controlled to be 1: 0.3-0.5: 0.1: 10-15.

Further, the silicon nitride composite filler is prepared by the following method:

step SS1, placing the nano silicon nitride in a drying oven at 110 ℃ for drying for 2h, then transferring the nano silicon nitride to a beaker filled with deionized water, carrying out ultrasonic treatment for 10min, carrying out magnetic stirring at the rotating speed of 150r/min, adding the dodecyl triethoxysilane after 15min, continuing stirring for 2h, then carrying out suction filtration, drying and grinding to obtain the treated nano silicon nitride, and controlling the weight ratio of the nano silicon nitride to the dodecyl triethoxysilane to be 2: 1;

and step SS2, adding deionized water into a three-neck flask, adding sodium dodecyl sulfate, dropwise adding 10% ammonia water to adjust the pH until the pH is =8, adding the treated nano silicon nitride prepared in the step S1, magnetically stirring for 10min, heating to 60 ℃, adding sodium persulfate, uniformly stirring for 10min at the temperature, adding methyl methacrylate and ethyl acrylate, heating to 80 ℃, reacting for 4h at the temperature, cooling to room temperature, filtering, washing with deionized water for three times, and drying at 100 ℃ for 3h to prepare the silicon nitride composite filler.

In the step SS1, the nanometer silicon nitride is treated by the dodecyl triethoxy silane, ethoxy groups on the dodecyl triethoxy silane can be hydrolyzed to form alcohol, and then alcoholic hydroxyl groups can react with the nanometer silicon nitride with hydroxyl groups on the surface, so that the step SS2 treats the surface of the nanometer silicon nitride by the dodecyl triethoxy silane, and the hydrophobicity of the nanometer silicon nitride is enhanced; adding sodium dodecyl sulfate and deionized water in the step SS2, performing ultrasonic treatment for 5min to enable the treated nano silicon nitride to form an emulsion system better and disperse the emulsion system in the solution, wrapping the outer layer of the nano silicon nitride with the sodium dodecyl sulfate, adding sodium persulfate serving as an initiator to enable methyl methacrylate and ethyl acrylate to diffuse into the outer layer of the sodium dodecyl sulfate wrapped in the nano calcium carbonate, and finally forming a composite filler taking the nano silicon nitride as an inner core and the methyl methacrylate, the ethyl acrylate and the sodium dodecyl sulfate as shells; the composite filler is mixed with the phenolic resin/carbon fiber composite material to be used as a wear-resistant base material, so that the interface layer of the brake pad can be enhanced, and the brake pad is endowed with excellent wear resistance.

Further, the weight ratio of the sodium dodecyl sulfate, the treated nano silicon nitride, the sodium persulfate, the methyl methacrylate and the ethyl acrylate in the step SS2 is controlled to be 3: 20: 0.1-0.3: 2.

A production process of a high-stability and friction-resistant brake pad comprises the following steps:

The invention has the beneficial effects that:

(1) the brake pad with high stability and friction resistance is prepared by phenolic resin/carbon fiber composite material, and silicon nitride composite filler and the like as raw materials, the phenolic resin/carbon fiber composite material and the silicon nitride composite filler can endow the brake pad with excellent wear resistance, and the phenolic resin/carbon fiber composite material has excellent thermal stability, in the preparation process of the phenolic resin/carbon fiber composite material, in the step S1, melamine and phenol are mixed in a three-neck flask, then oxalic acid and 10% formaldehyde solution are sequentially dripped to prepare a mixed solution A, the mixed solution A is actually the phenolic resin modified by the melamine, the nitrogen heterocycle is introduced in the preparation process of the modified phenolic resin, so that the thermal decomposition temperature of the phenolic resin can be increased, and the finally prepared brake pad is prevented from being decomposed when the friction temperature is raised to influence the service life of the brake pad; purifying the modified phenolic resin by tetrahydrofuran in step S2; soaking the carbon fiber in concentrated sulfuric acid for 2h in step S3, improving the activity of the surface of the carbon fiber and increasing the contact surface area of the carbon fiber through acid treatment, and then transferring the carbon fiber to KH550 for soaking for 3h to prepare the treated carbon fiber, wherein the surface of the carbon fiber has higher reactivity and can generate chemical bonds after being combined with phenolic resin so as to achieve the combination stability; then adding carbon fibers into the mixed solution B, drying, hot-pressing and molding to obtain the phenolic resin/carbon fiber composite material; the material has excellent wear resistance of carbon fiber and thermal stability of modified phenolic resin, and can prevent the prepared brake pad from being worn or decomposed due to temperature rise under the action of friction.

(2) The invention also prepares a silicon nitride composite filler, and in the preparation process, the nanometer silicon nitride is processed by the dodecyl triethoxy silane in the step SS1, the ethoxy on the dodecyl triethoxy silane can be hydrolyzed to form alcohol, and then the alcoholic hydroxyl can react with the nanometer silicon nitride with hydroxyl on the surface, so that the step SS2 processes the surface of the nanometer silicon nitride by the dodecyl triethoxy silane, and the hydrophobicity of the nanometer silicon nitride is enhanced; adding sodium dodecyl sulfate and deionized water in the step SS2, performing ultrasonic treatment for 5min to enable the treated nano silicon nitride to form an emulsion system better and disperse the emulsion system in the solution, wrapping the outer layer of the nano silicon nitride with the sodium dodecyl sulfate, adding sodium persulfate serving as an initiator to enable methyl methacrylate and ethyl acrylate to diffuse into the outer layer of the sodium dodecyl sulfate wrapped in the nano calcium carbonate, and finally forming a composite filler taking the nano silicon nitride as an inner core and the methyl methacrylate, the ethyl acrylate and the sodium dodecyl sulfate as shells; the composite filler is mixed with the phenolic resin/carbon fiber composite material to be used as a wear-resistant base material, so that the interface layer of the brake pad can be enhanced, and the brake pad is endowed with excellent wear resistance.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

secondly, adding the mixture into a press machine for pressing to obtain a semi-finished brake pad, controlling the pressing temperature to be 150 ℃, the pressing pressure to be 30MPa, and the pressing time to be 30 min;

and thirdly, performing heat treatment on the semi-finished brake pad, controlling the heat treatment temperature to be 180 ℃, performing heat treatment for 5 hours, and then performing flat chamfer, outer arc roughing, inner arc grinding, drilling and outer arc fine grinding to obtain the high-stability and friction-resistant brake pad.

The phenolic resin/carbon fiber composite material is prepared by the following method:

step S1, adding melamine and phenol into a three-neck flask, magnetically stirring at a rotating speed of 100r/min for 15min, heating to 45 ℃, dropwise adding oxalic acid, controlling the dropwise adding speed of the oxalic acid to be 3mL/min, heating to 55 ℃ after the dropwise adding is finished, continuously stirring for 30min, dropwise adding a formaldehyde solution with the mass fraction of 10%, and controlling the dropwise adding time to be 10min to obtain a mixed solution A;

step S2, transferring the mixed solution A into a reflux condenser, dropwise adding dilute hydrochloric acid with the mass fraction of 10% to adjust the pH until the pH =4, heating to 85 ℃, reacting for 5 hours at the temperature, then carrying out reduced pressure distillation, carrying out reduced pressure rotary distillation at 90 ℃ until the mixed solution A is not layered, and then purifying with tetrahydrofuran for three times to obtain the modified phenolic resin;

step S3, adding the carbon fibers into concentrated sulfuric acid with the volume fraction of 98% for soaking for 2 hours, taking out the carbon fibers, washing the carbon fibers to be neutral by using deionized water, adding the carbon fibers into KH550 with the mass fraction of 2% for soaking for 3 hours, and washing and drying the carbon fibers to obtain the treated carbon fibers; and (4) adding the modified phenolic resin prepared in the step (S2) into absolute ethyl alcohol according to the weight ratio of 1: 10, and then adding hexamethylene tetramine to prepare a mixed solution B, wherein the weight ratio of the modified phenolic resin to the hexamethylene tetramine is 1: 0.1.

And step S4, adding the treated carbon fiber into the mixed liquid B, carrying out ultrasonic oscillation for 25min, taking out, drying at 40 ℃, carrying out hot-press molding, controlling the hot-press temperature to be 100 ℃ and the pressure to be 10MPa, and preparing the phenolic resin/carbon fiber composite material, wherein the weight ratio of the treated carbon fiber to the mixed liquid B is controlled to be 1: 5.

The silicon nitride composite filler is prepared by the following method:

Example 2

The silicon nitride composite filler is prepared by the following method:

Example 3

The silicon nitride composite filler is prepared by the following method:

Example 4

The silicon nitride composite filler is prepared by the following method:

Comparative example 1

Compared with example 1, the preparation method of the comparative example, which replaces the phenolic resin/carbon fiber composite material with the phenolic resin, is as follows:

Comparative example 2

Compared with example 1, the preparation method of the comparative example, which replaces the silicon nitride composite filler with silicon nitride, is as follows:

Comparative example 3

The comparative example is a friction-resistant brake pad in the market.

The friction coefficients and wear rates of examples 1 to 4 and comparative examples 1 to 3 were measured, and the results are shown in the following table;

it can be seen from the above table that examples 1 to 4 had a friction coefficient of 2.3 to 2.5 at 100 ℃, a friction coefficient of 2.3 to 2.5 at 200 ℃, a wear rate of 0.18 to 0.22 at 100 ℃ and a wear rate of 0.22 to 0.25 at 200 ℃; comparative examples 1 to 3 had a friction coefficient of 3.0 to 3.3 at 100 ℃, a friction coefficient of 3.1 to 3.8 at 200 ℃, a wear rate of 0.35 to 0.40 at 100 ℃ and a wear rate of 0.36 to 0.40 at 200 ℃; therefore, methyl methacrylate and ethyl acrylate diffuse into the outer layer of sodium dodecyl sulfate wrapped in nano calcium carbonate to finally form a composite filler taking nano silicon nitride as an inner core and methyl methacrylate, ethyl acrylate and sodium dodecyl sulfate as shells; the composite filler is mixed with the phenolic resin/carbon fiber composite material to be used as a wear-resistant base material, so that the interface layer of the brake pad can be enhanced, and the brake pad is endowed with excellent wear resistance.

In the description herein, references to the description of "one embodiment," "an example," "a specific example" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The foregoing is illustrative and explanatory only and is not intended to be exhaustive or to limit the invention to the precise embodiments described, and various modifications, additions, and substitutions may be made by those skilled in the art without departing from the scope of the invention or exceeding the scope of the claims.

Claims

1. The high-stability friction-resistant brake pad is characterized by being prepared from the following raw materials in parts by weight: 5-15 parts of phenolic resin/carbon fiber composite material, 5-10 parts of coke powder, 10-15 parts of barite powder, 2-5 parts of silicon nitride composite filler, 2-5 parts of polyacrylonitrile fiber and 0.5-1.5 parts of calcium titanate fiber;

2. The high stability friction resistant brake pad of claim 1 wherein said phenolic resin/carbon fiber composite is made by the following method:

step S3, adding the carbon fibers into concentrated sulfuric acid with the volume fraction of 98% for soaking for 2 hours, taking out the carbon fibers, washing the carbon fibers to be neutral by using deionized water, adding the carbon fibers into KH550 with the mass fraction of 2% for soaking for 3 hours, and washing and drying the carbon fibers to obtain the treated carbon fibers; adding the modified phenolic resin prepared in the step S2 into absolute ethyl alcohol according to the weight ratio of 1: 10, and then adding hexamethylene tetramine to prepare a mixed solution B, wherein the weight ratio of the modified phenolic resin to the hexamethylene tetramine is 1: 0.1-0.2;

3. The brake pad of claim 2, wherein the weight ratio of melamine, phenol, oxalic acid and 10% formaldehyde solution in step S1 is controlled to be 1: 0.3-0.5: 0.1: 10-15.

4. The brake pad of claim 1, wherein the silicon nitride composite filler is prepared by the following steps:

5. The brake pad of claim 4, wherein the weight ratio of sodium dodecyl sulfate, treated nano silicon nitride, sodium persulfate, methyl methacrylate and ethyl acrylate in step SS2 is controlled to be 3: 20: 0.1-0.3: 2.

6. The process for producing a high-stability friction-resistant brake pad according to claim 1, comprising the steps of: